ALBERT

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 180〈/p〉 〈p〉Author(s): Hongling Bu, Dong Liu, Peng Yuan, Xiang Zhou, Hongmei Liu, Hongzhe Song, Baifa Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ethylene glycol monoethyl ether (EGME) adsorption method is an essential and available technique for measuring the total specific surface area (TSSA) of natural rock samples that usually contain an abundant amount of clay-organic matter (clay-OM) complexes. Occurrence sites and types of OM are believed to influence the EGME adsorption behaviors of clay-OM complexes. However, the influence of OM properties on the EGME adsorption mechanism remains unclear until now. In this study, interlayer montmorillonite (Mt)-OM complexes were prepared using the intercalation of OM with various contents and different length of alkyl chains, such as tetramethylammonium bromide (TMAB) and dodecyl trimethyl ammonium bromide (DTAB), based on the cation exchange. EGME adsorption experiments were performed on Mt, OM, and Mt-OM complexes. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the structural properties of the samples before and after EGME adsorption. The EGME adsorption capacities and the corresponding TSSA decreased after OM intercalation into the interlayer space of Mt. The OM content and the amounts of alkyl chains significantly affected the EGME adsorption behaviors of Mt-OM complexes. For short alkyl chain OM (TMAB), TSSA values of the Mt-OM complexes decreased with the increase of the interlayer OM content. However, for long alkyl chain OM (DTAB), the TSSA values showed a different variation tendency where the smallest TSSA did not appear in the Mt-OM complex with the highest DTAB content. The initial interlayer distance of Mt-OM complexes and the arrangement of interlayer OM are the primarily factors for EGME adsorption behaviors of the Mt-OM complexes. The large initial interlayer distance favored for incremental expansion of Mt. after EGME adsorption, which promoted EGME molecules entering into the interlayer space. The influence of the arrangement of interlayer OM are primarily involved in some newly formed micropores preventing EGME molecules from entering and more adsorption sites were occupied by OM with a higher ordered mode for the conformation of the alkyl chain and a higher packing density for the arrangement.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 180〈/p〉 〈p〉Author(s): Shiyu Jia, Mingde Fan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉By X-ray diffraction, thermal analysis, diffuse reflectance infrared spectrometry, solid state nuclear magnetic resonance (〈sup〉1〈/sup〉H and 〈sup〉29〈/sup〉Si), and transmission/high-resolution transmission electron microscopy, silanization of heat-treated halloysite samples (300–1200 °C calcination) using γ-aminopropyltriethoxysilane through condensation reaction was investigated. Driven by calcining at higher temperatures, the crystalline structure of halloysite transformed to metahalloysite (500–900 °C), mixed phases of γ-alumina, silica, and primary mullite (~1000 °C, accompanied by an exothermic reaction), and secondary mullite (1200 °C), sequentially; while the lower calcination temperature 300 °C failed to change the crystalline structure except for dehydrating surface moisture. In the calcining processes, the tubular morphology of halloysite remained largely unchanged in the range 300–900 °C with additional surface mottling at temperatures ≥600 °C, but got damaged at higher temperatures ≥1000 °C. For the still tubular-shaped calcined samples, the hydroxyl distribution of the 300 °C-calcined sample was similar to that of raw halloysite; while for other samples from 600 to 900 °C calcination, the inner-surface Al-OH groups gradually decreased until completely diminished, and the external surface Si-OH groups reached maximum at 700 °C with decreasing trends as the temperature deviated from 700 °C. The 700 °C-calcined sample with maximum Si-OH groups acting as reactive sites was thus optimal for silanization, giving the highest silane loading of 5.87 mass %, which would depend on the main modification sites at the tube external surface without strict space limitation, and the unignorable oligomerization reaction of silane species besides their grafting reaction in this case. These results would be very helpful for surface properties optimization of halloysite nanotubes by heat-activation followed by silane modification, and hence for the development of halloysite-based advanced materials.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719302625-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 180〈/p〉 〈p〉Author(s): Ke Wen, Jingming Wei, Hongping He, Jianxi Zhu, Yunfei Xi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Clay minerals intercalated with inorganic species, known as pillared interlayered clays, have received extensive attention in recent decades. In this work, by comparison with those of Keggin-Al〈sub〉13〈/sub〉, the formation processes of Keggin-Al〈sub〉30〈/sub〉 are discussed based on different hydrolysis reactions. X-ray diffraction (XRD), field-emission scanning electron microscope, and thermogravimetric analyses were applied to compare differences in crystal structure, morphology, and thermal stability between Keggin-Al〈sub〉13〈/sub〉 and Keggin-Al〈sub〉30〈/sub〉 (sulfates). High temperature and excess monomeric Al species are key factors controlling the transformation from ε-Keggin-Al〈sub〉13〈/sub〉 to δ-Keggin-Al〈sub〉13〈/sub〉 and finally to Keggin-Al〈sub〉30〈/sub〉. A decrease of the crystal symmetry from Keggin-Al〈sub〉13〈/sub〉 to Keggin-Al〈sub〉30〈/sub〉 was confirmed by shifts of reflections (and decreases of intensities) on XRD patterns. Keggin-Al〈sub〉30〈/sub〉 has a more compact structure, which leads to higher thermal stability. The distributions of functional groups and positive charges on the surface of Keggin-Al〈sub〉30〈/sub〉 result in a “lying flat” arrangement configuration in the interlayer region of montmorillonite. Exploring the behaviors of polycations as intercalants from their formation, transformation, and properties during the pillaring process may offer better understandings of the enhanced properties and wide applications of pillared interlayered clays.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719302613-ga1.jpg" width="396" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 180〈/p〉 〈p〉Author(s): Weiliang Tian, Zhong Li, Zhenhong Ge, Dongmei Xu, Kewei Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Well-defined vermiculite nanolayers have been exfoliated from nature mineral by a simple water-assisted anion-exchange approach. By self-assembly of vermiculite nanolayers with poly (vinyl alcohol), highly oriented vermiculite-polymer composite films were successfully achieved under the hydrogen bond interaction. The vermiculite nanolayers dispersed well in polymer matrix, inducing a long gas diffusion length and strong diffusion resistance. As expected, the mechanical strength and gas barrier property of the composite film with 12% vermiculite is improved by 43% and 63.7%, respectively. This work provides not only a cost-effective approach to obtain vermiculite nanolayers from nature mineral but also a promising route to fabricate food/drug packaging materials with good gas barrier properties.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S016913171930256X-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Melda Isler Binay, Salih Kaan Kirdeciler, Burcu Akata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Antibacterial electrostatic powder paint coating with intended esthetic criteria was specially formulated for industrial applications using single (Ag〈sup〉+〈/sup〉) and binary exchanged (Ag〈sup〉+〈/sup〉 and Zn〈sup〉2+〈/sup〉) zeolite A, which was prepared from local kaolin resources. Optimization studies on reaction parameters were conducted to obtain the most crystalline zeolite A from kaolin. The Ag〈sup〉+〈/sup〉 and Zn〈sup〉2+〈/sup〉 exchanged zeolite A samples prepared from kaolin were introduced as filler into the paint matrix during the electrostatic powder coating process. The antibacterial efficacy of the coatings was evaluated against 〈em〉E. coli〈/em〉 and 〈em〉S. aureus〈/em〉 based on Japanese Industrial Standard JIS Z 2801 method. Color analysis was also performed on these coatings in order to meet the least discoloration criteria, which is relevant to judge the quality of the coatings for industrial use. Single ion-exchanged coatings with Ag〈sup〉+〈/sup〉 resulted in discoloring effect, which was diminished by adding Zn〈sup〉2+〈/sup〉. The results indicated that the coatings containing both 2 wt% Ag〈sup〉+〈/sup〉 and 12 wt% Zn〈sup〉2+〈/sup〉 exchanged zeolite A exhibited 99.99% and 99.96% reduction for 〈em〉E. coli〈/em〉 and 〈em〉S. aureus〈/em〉, respectively. This was of special interest for zeolite A samples that were prepared from local kaolin resources with more significant discoloration due to using natural kaolin as raw material. In conclusion, a low cost and antibacterial powder paint formulation with desired esthetic criteria using zeolites was achieved for the first time using a combination of Ag〈sup〉+〈/sup〉 and Zn〈sup〉2+〈/sup〉 ions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303096-ga1.jpg" width="268" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Kris Dox, Renz Pareijn, Maarten Everaert, Erik Smolders〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Layered double hydroxides (LDH) are anionic clay minerals that have the potential to recycle phosphate (P) from urine and may yield efficient P fertilisers. The efficient P recovery requires P uptake to be relatively fast, ensuring small adsorption columns to reduce process costs. This study assesses the kinetics of P adsorption and desorption of three phase-pure MgAl LDH with varying Al content and a phase-pure ZnAl LDH, all prepared by coprecipitation. The adsorption kinetics (0–24 h) in agitated suspension showed that 90% of the capacity is reached within 5 h, with similar rate constants for model solution as for synthetic urine. The LDH with low Al content maintain structural properties during adsorption, while crystallinity reduces for LDH with high Al content. The combination of XRD analysis, speciation modelling and kinetic information suggest that P uptake by LDH includes a fast step of ligand exchange, followed by slower step of anion exchange in the interlayer. The latter process dominates in LDH with high Al content whereas the former dominates the LDH with low Al content. The XRD analysis and speciation modelling furthermore suggests precipitation as an additional P removal mechanism. The P desorption (0–2 weeks) showed that 〉95% of P could be desorbed from MgAl-LDH whereas only 51% of adsorbed P is desorbed from the ZnAl LDH. Continuous flow pilot-scale adsorption columns with pelletized MgAl LDH granules (1 mm diameter) recovered 〉70% of urine-P at residence times of only 1 min, up to point of 70% of exchange capacity beyond which the recovery decreased. These results show that the LDH technology for P recovery is efficient to recycle P into high potential fertilisers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Thiago M. Rossi, Juacyara C. Campos, Mariana M.V.M. Souza〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrocalumite is a lamellar double hydroxide widely used in catalysis and metal adsorption. Its use as CO〈sub〉2〈/sub〉 adsorbent is an innovation in this segment. In this research, tests showed high adsorption capacity, thermal stability and good performance in adsorption/desorption cycles, qualifying hydrocalumite as a promising CO〈sub〉2〈/sub〉 adsorbent. It was synthetized with molar ratio Ca/Al = 2 by coprecipitation and calcined at 600, 700 and 800 °C. The adsorption was processed in a thermogravimetric analysis device at 500 °C and desorption was carried out at 600 °C. The occurrence of chemisorption and physisorption was identified from the heat flow in the adsorption steps. Hydrocalumite calcined at 600 °C achieved high levels of CO〈sub〉2〈/sub〉 adsorption (4.21 mmol g〈sup〉−1〈/sup〉) and reversible fraction between 94 and 99%.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303102-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Yu-Che Hsu, Pei-Hsin Chang, Cheng-Nan Lin, Chia-Ying Li, Tzong-Yuan Juang, Yung-Chuan Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work describes a novel 〈em〉in situ〈/em〉 fermentation process to intercalate bioactive surfactin molecules into layered double hydroxides (LDH). The direct intercalation of surfactin into the LDH could only yield partially-intercalated surfactin/LDH hybrids, which were a mixture of LDH with the intercalated spacings of 10.8 Å and the pristine LDH at 8.3 Å. In contrast, the 〈em〉in situ〈/em〉 fermentation process resulted in a fully intercalated surfactin/LDH hybrids. The interspacing of the surfactin/LDH hybrids was 5.8 Å, after deducting the initial layer thickness of 5 Å. The 〈em〉in situ〈/em〉 fermentation could perform the surfactin intercalation to the LDH in 〈24 h. This paper is the first report concerning about the cell-mediate intercalation of biomolecules into LDH. Organic/inorganic biohybrids, such as these nanoscale LDH, can presumably act as biomolecule reservoirs and drug carriers. This 〈em〉in situ〈/em〉 fermentation process appears to be a flexible option for the biomolecules intercalation into layered nanomaterials. The self-destructive functionality of LDH made the surfactin-LDH biohybrid a potential candidate in agricultural or biomedical applications.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303059-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 181〈/p〉 〈p〉Author(s): Hui-Ran Jin, Xin-Yu Zhou, Yong Zhu, Guo-Fan Sun, Shi-Jie Ding, Jing Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, non-aqueous Fe(OH)〈sub〉3〈/sub〉/palygorskite dispersion was prepared and its liquid crystal phase behavior was investigated. Positively charged Fe(OH)〈sub〉3〈/sub〉 colloidal particles were put in to non-aqueous and organically modified palygorskite dispersion. The effects of organically treated palygorskite and Fe(OH)〈sub〉3〈/sub〉 on the preparation of stable palygorskite dispersion were characterized with FT-IR, XRD, Contact Angle measurement, Zeta potential detection, Settlement measurement and SEM, respectively. The addition of Fe(OH)〈sub〉3〈/sub〉 particles shifted the concentrations of the coexisting isotropic and nematic phases to higher values while at the same time markedly accelerated the phase separation. The influence of Fe(OH)〈sub〉3〈/sub〉 particles on the dispersion in magnetic field was also discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Hengxue Xiang, Jialiang Zhou, Yangkai Zhang, Mugaanire Tendo Innocent, Meifang Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The unique tubular structure and morphology of inorganic nanotubes makes them very useful supporting materials for thermal energy storage. Lending these properties in the form of composites together with traditional organic phase change materials (PCMs) can solve the existing energy storage and thermal stability problems in PCMs. Here, the acid-etching halloysite nanotubes (A-HNTs) are prepared and employed as inorganic supporting materials to encapsulate polyethylene glycol (PEG). The N〈sub〉2〈/sub〉 physisorption results indicated that the specific surface area and pore volume of A-HNTs increased from 45.4m〈sup〉2〈/sup〉/g, 0.243cm〈sup〉3〈/sup〉/g to 253.4 m〈sup〉2〈/sup〉/g and 0.621 cm〈sup〉3〈/sup〉/g before and after acid etching leading to an effective PEG load increase from 50 mass% to 70 mass% of composite PCMs. This increasing encapsulation capacity of PEG had a beneficial effect on the phase change performances and the latent heat of the prepared PEG/A-HNTs composite PCMs which reached 112 J/g (as compared to 70.64 J/g of PEG/HNTs). The temperature- regulating time of heat storage and release process were 〉500 s and 491 s respectively. Further, the DSC thermograms with 100 thermal cycles and TGA results demonstrated that the PEG/A-HNTs composites had an excellent thermal reliability and stability for preparing phase-change fibers by high-temperature melt spinning. The thermal enthalpy, thermal regulating time and relative temperature difference of resultant PA6/PEG/A-HNTs reached 13.57 J/g, 206 s and 3.2 °C, respectively.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Acid-etched halloysite nanotubes (A-HNTs)/polymer-based PCMs are designed and fabricated. The phase change enthalpy of PEG@A-HNTs composites reached up to 112 J/g (as compared to 70.64 J/g of PEG@HNTs), and the temperature-regulating time of heat storage and release process are 〉500 s and 491 s, respectively. The excellent heat resistance of PEG@A-HNTs makes them competent to prepare melt-spun PA6/PEG/A-HNTs phase change fibers. The thermal enthalpy, thermal regulating time and relative temperature difference of this fibes reached 13.57 J/g, 206 s and 3.2 °C, respectively〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303072-ga1.jpg" width="375" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Yanjun Ren, Haonan Wang, Zechen Ren, Ying Zhang, Yiran Geng, Liansong Wu, Xiaolin Pu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Clay is closely associated with the drilling of oil and gas by influencing the shale wellbore stability and the rheology of drilling fluids. In this work, four imidazolium-based ionic liquids (ILs) were used to modify the typical clay (i.e., sodium bentonite (Na-Bent)), and their effects on the Na-Bent rheological and swelling properties were evaluated by shear rheological measurements, immersion experiment, linear swelling measurements. The mechanisms involved were identified by using fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Zeta-potential and environmental scanning electron microscopy (ESEM) analysis. Evaluation experiment results showed that the adsorption of each IL could both significantly affect the Na-Bent rheological property and inhibit the Na-Bent swelling, which strongly depended on ILs' structures and concentrations. The mechanism study revealed that the cationic groups of ILs could adsorb on Na-Bent prior to water molecules, followed by expelling water and compressing the double electrode layers, and therefore inhibit the Na-Bent swelling. The adsorption of ILs could also change aggregation behaviors of the Na-Bent particles, by which the “house of cards” structures in Na-Bent dispersions were improved or destroyed, resulting in changes in rheological properties of Na-Bent dispersions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303060-ga1.jpg" width="436" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Yulin Wang, Tingting Huo, Chenxu Feng, Yali Zeng, Jie Yang, Xu Zhang, Faqin Dong, Jianjun Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Long-term exposure to chrysotile asbestos has been associated with an increased risk of pulmonary fibrosis, lung cancer, ovarian cancer and peritoneal mesothelioma. Although numerous pathophysiological mechanisms account for chrysotile asbestos-induced pulmonary toxicity, apoptosis has attracted considerable attention and has not yet been fully elucidated. Therefore, the goal of the current study was to determine whether chrysotile asbestos could cause oxidative stress and apoptosis in A549 cells and the potential mechanism of reactive oxygen species (ROS)-induced cell apoptosis. The experimental results showed that chrysotile asbestos significantly inhibited the proliferation of A549 cells. Additionally, chrysotile asbestos increased ROS in a dose-dependent manner. Excessive ROS injured the antioxidant defense system and caused lipid peroxidation, of which glutathione (GSH) and superoxide dismutase (SOD) were dramatically decreased while malondialdehyde (MDA) was significantly increased. Excessive production of ROS upregulated the expression of pro-apoptotic proteins p53 and Bax to depress the mitochondrial membrane potential (MMP) and promote cytochrome 〈em〉c〈/em〉 (Cyt c) release into the cytosol, which triggered the downstream apoptotic protein cleave-caspase-3 to induce cell apoptosis. Furthermore, 〈em〉N〈/em〉-acetyl-L-cysteine (NAC) was applied to inhibit the production of ROS. NAC pretreatment hindered the decrease of MMP, reduced expression of p53, Bax and Cyt c, downregulated cleave-caspase-3 and reduced cellular apoptosis. In conclusion, chrysotile asbestos caused mitochondrial dysfunction and cell oxidative stress to induce apoptosis 〈em〉via〈/em〉 the p53-regulated mitochondrial pathway. Our research results provided a fundamental basis for a toxicity discussion and rational utilization of chrysotile asbestos.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303035-ga1.jpg" width="494" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Mihaela Darie, Elena M. Seftel, Myriam Mertens, Radu G. Ciocarlan, Pegie Cool, Gabriela Carja〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The quest to provide clean water has led to a tremendous boost in the synthesis of advanced photocatalysts that are able to decontaminate water by harvesting the solar energy. Herein, a tandem of Pt or both Pt-Ag nanoparticles on layered double hydroxides (LDH) photocatalysts were obtained via a green chemical procedure in which LDH serve a dual function of both facilitating the synthesis of nanoparticles of Pt and Ag and acting as a support. Detailed characterization showed that the LDH structure is well-retained, while small nanoparticles of Pt or Pt-Ag are formed and dispersed on the larger nanoparticles of the LDH. The effects of the heterometallic composition of the 2-D LDH layers (e.g. Zn2Al; Zn2FeAl) and the mono/bi-metal (Pt/Pt-Ag) identity on the solar-light-induced catalytic performances were investigated using p-nitrophenol (p-NPh) as a targeted pollutant. Pt-Ag synergistic activity was superior to Pt alone to promote p-NPh degradation and Pt-Ag/Zn2Al exhibited the best photocatalytic activity approaching 77% degradation and 71% mineralization of p-NPh, after 6 h under solar light, at room temperature. The introduction of Fe in the LDH layers caused a significant change in the degradation pathway of p-NPh and drastically decreased the catalytic response such that p-NPh mineralization was only 10% for Pt-Ag/Zn2FeAl. Even though UV–vis analysis showed that Pt-Ag/Zn2FeAl had a stronger absorption of the visible light than Pt-Ag/Zn2Al, the PL data indicated a significant increase in the photoluminescence signal for Pt-Ag/Zn2FeAl as compared to Pt-Ag/Zn2Al. This suggested a retard recombination of electrons-holes in Pt-Ag/Zn2Al and revealed the active role of the LDH multimetallic composition to establish an effective electronic coupling between the constituent nanounits. These findings may aid in the rational design of multimetallic heterostructures that can effectively harvest sunlight for environmental cleanup.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303084-ga1.jpg" width="377" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 182〈/p〉 〈p〉Author(s): Kaoutar El Hassani, Hajar Jabkhiro, Daina Kalnina, Buscotin Horax Beakou, Abdellah Anouar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Freeze-dried sulfate intercalated layered double hydroxides (LDH) phase was synthetized by coprecipitation method via direct intercalation of sulfate anion. The effect of freeze-drying process on LDH properties was investigated. The resulting phase was evaluated for its efficiency in the intercalation of the reactive azo dye, Remazol Brilliant Red F3B (RR-F3B). The freeze-dried phase exhibited a low crystallinity and narrow particle size distribution compared to conventional LDH phases. The freezing step led to highly aggregated nanoparticles with a characteristic distance d〈sub〉003〈/sub〉 of 8.12 Å. The preferential arrangement of the intercalated dye species was examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The results showed that RR-F3B molecules were partially accommodated between the LDH layers as single-layer with horizontal orientation. The effect of drying on morphological and structural properties can be attributed to several stresses during freezing and drying steps.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 181〈/p〉 〈p〉Author(s): Chujun Lai, Tianqu He, Xuewen Li, Fang Chen, Linhai Yue, Zhaoyin Hou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Catalytic wet air oxidation (CWAO) of phenol has attracted much attention because of its high versatility and remarkable economy-scale advantages. In this submission, a series of M〈sub〉3〈/sub〉-Al-500 catalysts (with M = Cu, Mn, Fe, Ni, Zn and Co) were prepared via controlled calcination of layered double hydroxides, and tested in the CWAO of high concentrated phenol (2.1 g/L) with air under mild condition (120 °C and 1.0 MPa). It was found that Cu〈sub〉3〈/sub〉-Al-500 was the most active among these tested catalysts as phenol converted completely within 2 h. Characterizations indicated that the performance of Cu-based catalyst could be attributed to the redox transitions of Cu〈sup〉2+〈/sup〉/Cu〈sup〉+〈/sup〉 and/or the formation of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 in reaction mixture. At the same time, the surface acidity of Cu〈sub〉3〈/sub〉-Al-500 can also accelerate the degradation of phenol. The possible degradation mechanism of phenol over Cu-based catalyst was proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719303114-ga1.jpg" width="226" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 168〈/p〉 〈p〉Author(s): Derrick S. Dlamini, Jianxin Li, Bhekie B. Mamba〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper reviews the literature on clay/polymer (CP) based mixed-matrix membranes (MMM) for water treatment. Clay minerals have been credited for ultrafiltration (UF) membranes behaving like nanofiltration (NF) membranes in terms of salt rejection through the repulsion mechanism. This is interesting and more attention should be focused on this approach. There is an apparent agreement in the literature that the observed increase and then decrease in water flux with an increase in clay mineral loading is a result of viscosity changes in the casting solution. While this is true, there is still a need for studies that will consider that the clay mineral sheets are much larger compared to water molecules and are impermeable; hence, at higher loading they may impede water flow. Exfoliated clay platelets are basically similar to graphene oxide, which has gained significant attention lately in water treatment studies; however, to date, there is no information on the effect of the delaminated structures on the performance of available CP membranes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 168〈/p〉 〈p〉Author(s): L. Meili, P.V. Lins, C.L.P.S. Zanta, J.I. Soletti, L.M.O. Ribeiro, C.B. Dornelas, T.L. Silva, M.G.A. Vieira〈/p〉 〈div xml:lang="en"〉〈div〉 〈h6〉Abstract〈/h6〉 〈p〉In this work, LDH-biochar composites were synthesized in different molar ratios of Mg:Al (2:1, 3:1 and 4:1) using co-precipitation method. The composites were applied to remove an organic dye from aqueous solutions by adsorption. The composites and the pure bovine bone biochars were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) measurements, thermogravimetric analysis (TG/DTG), dispersive energy spectroscopy (DES) and scanning electron microscopy (SEM). The methylene blue dye adsorption experiments were conducted in a finite bath. The results indicate that pH 12 is more suitable for dye adsorption process, with a removal 〉95% for all composites. The adsorption kinetic was best described by the pseudo-second order model, reaching the equilibrium in approximately 20 min. The Redlich-Peterson model fit the adsorption equilibrium isotherms satisfactorily. It was obtained a maximum adsorption capacity of 406.47 mg·g〈sup〉−1〈/sup〉 at 40 °C. Negative values of ΔG indicate the spontaneity of the adsorption process. The positive value of ΔH (30.72 kJ·mol〈sup〉−1〈/sup〉) indicates the physical nature of the adsorption and the positive value of ΔS (0.1863 kJ·mol〈sup〉−1〈/sup〉) indicates that there was a change in the structure of the adsorbent and increased randomness during the fixing of the dye.〈/p〉 〈/div〉〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Hao Hu, Jun Ni, Dongqing Cai, Huilan Zhang, Minghao Li, Xian Shu, Caiguo Tang, Lifang Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Wheat powdery mildew (PM) is one of the world's top 10 most destructive fungal plant pathogen and the routine control of this disease is by application of fungicides and disease-resistant cultivars. In this study, a nanocomposite composed of amino silicon oil (ASO) and palygorskite (Pal) was developed and can effectively inhibit the pathogen. The results demonstrated that the morphology and microstructure of Pal could be effectively modified by ASO via hydrogen bonds between –NH〈sub〉2〈/sub〉 of ASO and − OH of Pal, resulting in an increase of hydrophobic surface groups. Further analysis showed that nanonetworks were formed by Pal-ASO interaction, which could effectively segregate 〈em〉Blumeria graminis〈/em〉 f. sp. 〈em〉tritici〈/em〉 (〈em〉Bgt〈/em〉) conidia from wheat leaf surface and reduce the disease index by 98%. This work provides an economic and environmentally friendly approach to control the wheat powdery mildew disease.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Reshmi C.R., Suja P. Sundaran, Subija T., Sujith Athiyanathil〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel “nano in micro” architecture composite electrospun membrane has been fabricated with Poly (ɛ-caprolactone) (PCL). Nano sheets of montmorillonite (Mt) can act as drug cargoes in PCL electrospun membranes. The fiber morphology and diameter of PCL/Mt. electrospun membranes were tuned by optimization of various electrospun parameters. Higher concentration of Mt. loaded electrospun membranes exhibited improved crystallinity and hydrophilicity. The 〈em〉in vitro〈/em〉 degradation studies of PCL/Mt. electrospun membranes explored a new scenario of degradation mechanism. PCL/40Mt membranes showed enhancement in human dermal fibroblast (HDFs) adhesion and proliferation. The vitamin B12 loaded Mt. nano-sheets incorporated in electrospun membranes exhibited extended release of the drugs over 15 days. Moreover, the pH responsive nature of PCL/40Mt electrospun membranes was also investigated. Gentamicin is the antibacterial drug loaded on PCL/40Mt membrane and showed bioactivity against 〈em〉E. coli〈/em〉 for 15 days. The newly fabricated nano in micro architecture membranes can be used as potential material for tissue engineering and sustained drug delivery.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S016913171830379X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Alastair Marsh, Andrew Heath, Pascaline Patureau, Mark Evernden, Pete Walker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Using alkali activation, un-calcined soils have potential as precursors for low carbon, low cost, geopolymer-stabilised construction materials. This technology has been recently promoted as a lower impact alternative to cement stabilisation for walling materials in construction around the world. There is a lack of fundamental understanding around the alkali activation of un-calcined montmorillonite and illite, which, along with kaolinite, are clay minerals commonly found in soils. Kaolinite, as a 1:1 clay mineral, has been shown to form crystalline hydrosodalite when alkali-activated, but 2:1 montmorillonite and illite could form stronger geopolymer structures due to the higher Si:Al ratio in the precursor mineral. The lack of understanding of the underlying mechanisms at work with 2:1 clay minerals is a barrier to knowing how viable un-calcined geopolymer stabilised soil materials are for the range of soil types found in nature. In this study, montmorillonite and illite precursors were activated with a range of sodium hydroxide concentrations, compacted, and then cured at 80 °C for 24 h. The cured samples were characterised using a variety of advanced analytical techniques, including powder XRD, SEM, TGA, 〈sup〉27〈/sup〉Al and 〈sup〉29〈/sup〉Si-MAS-NMR, and FTIR. For the first time it was confirmed that alkali activation of uncalcined montmorillonite forms a NASH or (N,C)ASH geopolymer as the major product phase, which increases in quantity with increasing Na:Al molar ratio of the system. Although it has a similar Si:Al ratio, alkali activation of illite seems to result in structural alteration and increased porosity for Na:Al ≥ 0.5. The behaviour of these individual clay minerals suggests that the alkali activation of un-calcined 2:1 clay minerals is complex. Although alkali activation of montmorillonite can form a geopolymer, alkali activation of soils containing illite may lead to poor quality materials. This research has shown that the focus of future development work should be around montmorillonite-based clays.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304101-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Lila Djouadi, Hussein Khalaf, Horiya Boukhatem, Hocine Boutoumi, Amina Kezzime, J. Arturo Santaballa, Moisés Canle〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The photocatalytic degradation of Ketoprofen (KP), 2-(3-benzoylphenyl)-propionic acid was studied under near UV–Vis irradiation (NUV-Vis) using supported photocatalysts. Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉-montmorillonite (Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉-Mt) photocatalysts were synthesized using a two- step ion exchange and impregnation method, and characterized using different techniques: Fourier transform infrared spectra (FTIR), X-ray fluorescence (XRF), X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and photo-electrochemistry. Successful intercalation of TiO〈sub〉2〈/sub〉 and Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 in the montmorillonite (Mt) was carried out, and the corresponding energy diagram for the Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉 heterojunction has been proposed. The resulting Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉-Mt nanocomposites were able to degrade KP under NUV–Vis irradiation. KP photodegradation was monitored by HPLC. The kinetics of photocatalytic transformation followed the Langmuir-Hinshelwood kinetic model. Pseudo-first-order kinetics adequately fitted the experimental data (t〈sub〉½〈/sub〉〈em〉ca.〈/em〉 17 min at pH 11, t〈sub〉½〈/sub〉〈em〉ca.〈/em〉 44 min at pH 3. 0.5 g·L〈sup〉−1〈/sup〉 Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉 (25/75)-Mt nanocomposite). Factors affecting the kinetics of the process, such as the different Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉 ratio and initial pH solution have been discussed. KP photoproducts were identified using HPLC-MS, and the corresponding reaction mechanism has been proposed. Photodegradation of KP over Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉-Mt nanocomposites under NUV-Vis irradiation starts with the decarboxylation of KP and subsequent hydroxylation by HO〈sup〉•〈/sup〉 and oxidation by HO〈sup〉•〈/sup〉 and other reactive oxygen species (ROS) leads to the formation of photoproducts. TiO〈sub〉2〈/sub〉 and Bi〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 intercalated in the montmorillonite are cheap and efficient nanocomposites for the abatement of persistent organic pollutants (POP), such as KP, using NUV-Vis light.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304071-ga1.jpg" width="261" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Yong-Gui Chen, Xin-Xin Dong, Xu-Dong Zhang, Wei-Min Ye, Yu-Jun Cui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sufficient swelling pressure of compacted bentonite upon wetting is necessary to provide long-term stability to an engineered barrier system under conditions of thermal gradient and variable water chemistry in a high-level radioactive waste repository. To investigate the combined thermal and saline effects on the swelling pressure of Gaomiaozi (GMZ) bentonite, constant-volume swelling pressure tests were performed on densely compacted specimens inundated with deionized water, NaCl, and CaCl〈sub〉2〈/sub〉 solutions at 20 °C and 60 °C. The results indicate that high temperature and saline solutions decrease the swelling pressure. Crystalline swelling dominates the constant-volume swelling of densely compacted bentonite. For a given cation type, a higher temperature or higher solution concentration resulted in a lower swelling pressure. The decreasing surface potential and increasing osmotic suction with solution concentration both weaken the clay swelling. The effects of temperature on the swelling pressure are explained by the role of the lattice contraction. The degeneration of the interlamellar adsorbed water at high temperature weakens the crystalline swelling. The effects of cation types are interpreted by their difference in chemical activity. Ca〈sup〉2+〈/sup〉 ions possess higher exchange capacity and larger hydrated radius than those of the Na〈sup〉+〈/sup〉 ions. When densely compacted Na-bentonite is wetted with CaCl〈sub〉2〈/sub〉 solution, the possible change of the interlamellar cations from Na〈sup〉+〈/sup〉 to Ca〈sup〉2+〈/sup〉 ions would promote the crystalline swelling. The osmotic suction imposed by CaCl〈sub〉2〈/sub〉 solution may offset the role of the cation exchange to a small extent. The effect of temperature on the swelling pressure exceeds that of the cation types. For a given solution concentration, the specimen wetted with NaCl solution developed lower swelling pressure than that with CaCl〈sub〉2〈/sub〉 solution at 20 °C, whereas the opposite tendency appeared at 60 °C. In addition, specimens saturated with deionized water and NaCl solution at 20 °C obtained insignificant difference in pore size distribution, whereas identifiable differences in pore size distribution occured at 60 °C. The combined thermal and saline effects on the swelling pressure may be explained by the role of the lattice contraction at varied clay structure. When CaCl〈sub〉2〈/sub〉 solution is used, the quasicrystals contain more montmorillonite layers than the case of the NaCl solution. The role of the lattice contraction at high temperature is expected to decrease the swelling pressure to a greater degree in the case of the CaCl〈sub〉2〈/sub〉 solution. The remarkable increase in the osmotic suction at high temperature and high solution concentration could also enlarge the decrease in the swelling pressure. These conjectures, however, still require quantitative interpretations via microscopic tests such as X-ray powder diffraction tests on bulk samples.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Liva Dzene, Jocelyne Brendlé, Lionel Limousy, Patrick Dutournié, Christelle Martin, Nicolas Michau〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Examples in materials science and in geology show an interest for iron-rich tri-octahedral clay mineral synthesis in large amounts and with well-defined characteristics. This review summarizes previously reported methods and conditions for iron-rich tri-octahedral clay mineral synthesis. Two approaches of hydrothermal synthesis have been applied: using gel or solid precursors. The most common synthesis approach is the hydrothermal synthesis using gel precursor. The synthesis of 1:1 type clay minerals were performed in reducing conditions in neutral or alkaline pH at various temperature and time ranges. The experimental conditions for 2:1 type clay mineral synthesis were in most cases similar to 1:1 type clay minerals, with in addition acidic pH and oxidizing conditions. The most commonly used methods for identifying and characterizing these minerals are X-ray diffraction, infra-red and Mössbauer spectroscopies as well as transmission electron microscopy. The thermodynamic stability of synthesized phases, as well as the reason for elements adopting a definite configuration and distribution in solid phase remain open questions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304277-ga1.jpg" width="318" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Santiago Arias, Lenivaldo V. Sousa, Celmy B.M. Barbosa, Antonio Osimar S. Silva, Roger Fréty, Jose Geraldo A. Pacheco〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrotalcite-like materials were synthesized by pH-controlled precipitation method with Ni〈sup〉2+〈/sup〉 and Al〈sup〉3+〈/sup〉 cations and terephthalate as the compensation anion. Ni/Al ratios were 1.0 and 0.3, both high in aluminum content for what has been commonly reported in the literature for this type of materials. The incorporation of Zr(IV) in the structure of the materials was evaluated substituting Al(III) for Zr(IV), using Al/Zr ratios of 3.0 and 0.3. Characterization techniques, such as X-ray diffraction, thermogravimetric analysis, infrared spectroscopy and chemical analysis, demonstrated that NiAlZr-terephthalate hydrotalcite-like materials were obtained simultaneously with amorphous phases of ZrO〈sub〉2〈/sub〉 and Al(OH)〈sub〉3〈/sub〉. The mixed oxides, produced by the calcination of the hydrotalcites, had interesting characteristics that could be useful for potential unsupported mesoporous nickel catalysts, with high surface areas, nanoparticles, variable reducibility temperature, thermal stability and different kinds of interaction of nickel with aluminum and zirconium, depending on the metal content. These NiAlZr oxides were evaluated as catalysts for cyclohexane dehydrogenation reaction after a reduction process. The resulting catalysts presented a high cyclohexane conversion and in some cases selectivity to benzene close to 90%, especially when zirconium was added and nanosized cristallites of NiO were formed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304198-ga1.jpg" width="319" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Zhijia Xue, Xiaowei Tang, Qing Yang, Zhifeng Tian, Yao Zhang, Wei Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electro-osmotic chemical methods were applied in a series of geotechnical studies in which various solutions were injected into clay samples, increasing the undrained shear strength of the clay. Such methods resulted in a series of phenomena and in clay property evolution. In this study the current, temperature, settlement, drainage volume, and electrical potential distribution during the electro-osmotic experiments were monitored as process data, and the electrical conductivity in clay, calcium content, pH, water content, and undrained shear strength after the electro-osmotic chemical experiments were measured as clay property evolution data. Based on the process data, clay property data, and relevant theories, the mechanism of clay reinforcement with electro-osmotic chemicals was comprehensively explained. The development of an electro-osmotic permeability coefficient difference and the permeable drainage boundary condition resulted in a negative pore water pressure distribution shaped as an arch, which resulted in the water content having the same distribution and induced settlement. Because of the gathering of Ca〈sup〉2+〈/sup〉 and H〈sup〉+〈/sup〉 near the anode, a chemical cement reaction occurred near the cathode. The electrical potential gradient near the anode was lower than that near the cathode. Because of the chemical cement reaction between Ca〈sup〉2+〈/sup〉, OH〈sup〉−〈/sup〉, and SiO〈sub〉3〈/sub〉〈sup〉2−〈/sup〉, the undrained shear strength near the cathode was much higher than that near the anode. In addition, a coupling analysis of the electro-osmotic chemical process and clay property evolution is presented at the end of the discussion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Germán Pérez-Sánchez, Tiago L.P. Galvão, João Tedim, José R.B. Gomes〈/p〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Fahimeh Beigi, Matin Sadat Saneei Mousavi, Faranak Manteghi, Mohammadreza Kolahdouz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a novel Ionic Polymer Metal Composite (IPMC) has been fabricated by chemical electroless plating integrated with doping Layered Double Hydroxide (LDH) nanoparticles in the nafion polymeric matrix. Platinum, as a noble metal, was used for electrode deposition of the prepared doped nafion and successfully act as a high-quality electrode to transfer electrical signal. This IPMC, in fact, is a smart material suggesting to acts as a high responsive mechanical humidity sensor in biomedical devices since it produced a remarkably higher voltage with higher sensitivity and responsivity in comparison to the previous IPMC humidity sensors in literature. LDH nanoparticles own a layered ionic structure, which makes them highly hydrophilic. This property increases the water uptake of the IPMC. By increasing the penetration of water molecules in the nafion channels, the separation of positive and negative charges becomes easier and leads to higher and faster humidity sensing application. The humidity sensing applications of undoped and LDH-doped IPMC fabricated by facile chemical plating method were measured and compared at different bending angles. It was found that 1% doped nafion sheet had the highest water uptake of 30%, and consequently better humidity sensing compared to the undoped, 0.5%, 1.5%, 2% and 3% doped nafion. This means that doping concentration and modification has an optimized value.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Zichen Yin, Yanling Wang, Jingshan San〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydroxypropyl guar gum (HPG) is a kind of thickener commonly used in the field of oilfield chemistry. The adsorption behavior of HPG onto Montmorillonite (Mt) was investigated in this article. The maximum adsorption amount of HPG on Mt. was 3.6 mg/g at the HPG concentration of 2 g/L. The effect of pH, temperature, salts, alcohols and hydrolyzed polyacrylamide (HPAM) on adsorption behavior was revealed. The results showed that adsorption capacity increased with pH ranging from 3 to 13. The adsorption capacity was slightly influenced at temperature from 20 °C to 60 °C. The adsorption amount decreased at the presence of NaCl, KCl, CaCl〈sub〉2〈/sub〉 or MgCl〈sub〉2〈/sub〉, while it increased with addition of Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 or Na〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉. The adsorption capacity was found no change at the presence of monobasic alcohol, while it significantly increased with the increasing concentration of polybasic alcohol. The adsorption density reduced with the addition of HPAM. Scanning electron microscope (SEM) and X-ray Diffraction (XRD) confirmed that adsorption behavior occurred on the exterior surface of Mt. Besides, the adsorption was attributed to Van der Waals' forces and electrostatic interaction. The Fourier Transform infrared spectroscopy (FTIR) showed that adsorption behavior occurred on Mt. surface via physisorption rather than chemisorption. The adsorption behavior of HPG on Mt. surface obeyed the Langmuir adsorption isotherm which showed that the adsorption was monolayer adsorption. The adsorption mechanism would be characterized as exterior surface adsorption, physical adsorption and monolayer adsorption.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): E.M. Seftel, R.G. Ciocarlan, B. Michielsen, V. Meynen, S. Mullens, P. Cool〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study focuses on the phosphate uptake by synthetic ZnAl-layered double hydroxides having different charge density due to the modification of the cationic ratio (Zn〈sup〉2+〈/sup〉/Al〈sup〉3+〈/sup〉) within the brucite-like sheets. The structure of the as-synthesized ZnAl-LDH was confirmed by X-ray diffraction and 〈sup〉27〈/sup〉Al NMR and micro-Raman spectroscopy characterization techniques. The materials were applied for sorption of phosphate anions in aqueous media under relevant conditions. Parameters affecting the sorption process were thoroughly investigated, such as the layer cationic ratio, the exchangeable interlayer anion, thermal treatment and competitive sorption in the presence of co-existing anions. The sorption data provided information regarding the relationship between the phosphate uptake and the physical-chemical properties of these materials. The phosphate adsorption onto the non-calcined LDH occurred via the anionic exchange mechanism while both structural reconstruction and precipitation mechanisms were observed for the calcined materials. The obtained results suggest that the Zn containing LDH are suitable candidates for the phosphate recovery or removal from aqueous media in wastewater treatment processes.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S016913171830382X-ga1.jpg" width="378" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 October 2016〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science〈/p〉 〈p〉Author(s): Shengmin Luo, Dongwei Hou, Guoping Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hedan et al. (2015) recently reported an interesting method for determining the elastic modulus of vermiculite, a representative swelling clay mineral. A platy natural macrocrystal of vermiculite was used in the study. The technique combining mechanical compression and digital image correlation (DIC) appears plausible. However, a fundamental issue related to the reported testing method, particularly the experimental setup and specimen geometry constraints, arises and is worth re-examination and discussion, because it may make the reported modulus inappropriate or inaccurate. In this short discussion, the stress distribution of a thin plate such as the tested vermiculite macrocrystal under uniaxial compression is analyzed, and the reported results are re-interpreted. It appears that the reported Young's modulus of 32.3 GPa is too high for the studied vermiculite.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 19 April 2017〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science〈/p〉 〈p〉Author(s): M. Suárez, E. García-Romero〈/p〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Agustín Molinero Guerra, Patrick Aimedieu, Michel Bornert, Yu-Jun Cui, Anh Minh Tang, Zhao Sun, Nadia Mokni, Pierre Delage, Frédéric Bernier〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pellet/powder bentonite mixture is one of the candidate materials for sealing plugs in deep geological high-level radioactive waste disposal. This note presents an investigation on the structure changes of this mixture occurring during the saturation process by means of X-ray computed micro-tomography. The test was performed in an infiltration column (60 mm in inner diameter and 120 mm in height). Water was supplied to the two ends of the column and the changes of the sample morphology were observed during a period of 100 days of hydration. Digital Volume Correlation (DVC) technique was used to determine the vertical displacement field of the bentonite powder. A pressure transducer was used to measure the axial swelling pressure during the hydration. The results show that the initial distribution of powder in the inter-pellet pores was not homogeneous; the powder filled almost completely the pores in the zones close to the two ends while air-filled inter-pellet voids were observed in the middle of the column specimen. When water started to infiltrate inside the specimen from both ends, the pellets and the powder grains started to swell (because of the swelling properties of smectite, the principal mineral of bentonite) and filled the voids. That induced at the same time increase of swelling pressure and downward movement of powder grains. The results allowed a better understanding on the hydro-mechanical couplings, at the pellet scale, in the pellet/powder bentonite mixture upon wetting.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Manuel Pozo, Francisco Armijo, Francisco Maraver, José Manuel Ejeda, Iluminada Corvillo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The liquid phase of a peloid can be mineral-medicinal, marine or salt lake water. This study was designed to experimentally determine the interaction between two bentonites and one sepiolite, and seawater as well as dilutions thereof to verify the effect of salinity on instrumental texture measurements in clay-water mixtures prepared with these components. In all the clay-water mixtures tested, instrumental hardness and adhesiveness decreased with water content. For a given instrumental hardness or adhesiveness, bentonite retained more water in the mixture with distilled water than with seawater. In contrast, sepiolite retained more water in the mixture with seawater than with distilled water. These differences affected the thermal behaviour of the clay-water mixtures. Instrumental hardness and adhesiveness curves may be a suitable tool to tailor concentrated dispersions and after maturation could be used in thalassos and medical spas as peloids.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Y. Chen, M.A. Glaus, L.R. Van Loon, U. Mäder〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Determining the retardation properties of argillaceous media for dissolved low molecular weight organic compounds (LMW—OC's) is still an open issue in the assessment of the migration behaviour of 〈sup〉14〈/sup〉C in the near and far field of a deep geological repository of radioactive wastes. Here we report retardation factors of potential carriers of organic 〈sup〉14〈/sup〉C (carboxylates and alcohols) in binary clay mixtures (kaolinite and illite) as well as in Opalinus Clay (OPA), the favoured host rock for the deep geological disposal of radioactive waste in Switzerland. The percolation technique with a pulse injection of the LMW-OC's was used for all measurements. The transferability of sorption values of the LMW-OC's gained on the single-mineral systems (kaolinite and illite, respectively) to the binary clay mixtures and to clay rock (OPA) was tested.〈/p〉 〈p〉For binary clay mixtures, percolation experiments were carried out using tritiated water and 〈sup〉36〈/sup〉Cl〈sup〉−〈/sup〉 as the reference tracers. The retardation factors predicted by the component additivity approach (CA) were consistent with the measured ones. Deuterated water and bromide were used as reference tracers in experiments with OPA. Complex breakthrough curves of bromide and the test compounds were observed here. Heterogeneities of the pore space are proposed as the main reason to explain the complex structure of breakthrough curve. Additionally, (a)biotic degradation or transformation of the organic compounds over the long experimental duration possibly further added to the complexity of the results in some cases. The derivation of sorption distribution ratios (〈em〉R〈/em〉〈sub〉d〈/sub〉), determined from the breakthrough curves was therefore inherently associated with large uncertainties. The transferability of retardation data gained on less complex systems to the conditions of OPA was tested using the CA and the global composite (GC) approach. Significant discrepancies were found between the measured values and those predicted by the CA approach. The discrepancies were found to be smaller using the GC approach. In that case, the results obtained for single- and binary clay systems were also used for calibration purposes. Retardation factors of the LMW-OC's in OPA were then predicted based on two empiric relationships. The observed discrepancies are most probably related to the different chemical composition of the aqueous solution (e.g. ionic strength, pH), the various mineralogical features (e.g. compaction), and the different hydraulic conditions within the clay systems (e.g. Darcy flux). The absence of anion-sorption in OPA may be particularly explained by differences in the pH of the OPA pore water and the pore water in compacted kaolinite samples.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Annette Süssenberger, Klaus Wemmer, Susanne Theodora Schmidt〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 〈sup〉40〈/sup〉Ar* retentivity behavior was studied in the contact metamorphic aureole of the Torres del Paine intrusion (51°S, Chile) and provides constraints on the closure temperature in contact metamorphic settings. The temperature conditions of the regional anchizonal to epizonal metamorphosed pelitic host rock and the contact metamorphic pelite were recorded by illite crystallinities (Kübler Index) and by Raman spectroscopy on carbonaceous matter. K/Ar age determinations were carried out on illite fine fractions (〈0.2 and 〈 2 μm). Differing reaction progresses are observed between organic matter and illite. Organic matter equilibrated with the ambient temperatures, whereas illite is lacking behind the contact metamorphic conditions evident by the absence or limited recrystallization progress. We propose two models to explain the degassing of 〈sup〉40〈/sup〉Ar* in the absence of recrystallization considering surface loss and volume diffusion as two main pathways. Incipient 〈sup〉40〈/sup〉Ar* loss appears at temperatures of about 248 °C in the 〈0.2 μm and at 260 °C in the 〈2 μm fraction. The high temperature end of 〈sup〉40〈/sup〉Ar* retentivity is derived by extrapolation yielding temperatures of 330 °C for the 〈0.2 μm fraction and 345 °C for the 〈2 μm fraction. Thus, the Zone of incipient 〈sup〉40〈/sup〉Ar* loss, called ZIAL, is constrained to between 248 °C and 330 °C for the 〈0.2 μm fraction and to between 260 and 345 °C for the 〈2 μm fraction. The extrapolated values for the upper ZIAL limit are in good agreement with calculated bulk closure temperature values of 348 °C (〈2 μm) and 286 °C (〈0.2 μm) assuming ca. 10 kyrs of heating during the emplacement of the Torres del Paine intrusion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Anand Kabadagi, Santosh Chikkamath, Jayappa Manjanna, Satoru Kobayashi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The solid state reaction between Fe(II)−montmorillonite (〈strong〉Mt〈/strong〉) and 〈em〉o〈/em〉−phenanthroline (〈strong〉L〈/strong〉) resulted in the 〈em〉in-situ〈/em〉 complexation of interlayer Fe(II) ions with L. The formation of the [FeL〈sub〉3〈/sub〉]〈sup〉2+〈/sup〉 complex in the interlayer was confirmed from X−ray diffraction (XRD), thermal analysis (TG/DTA), infrared (FT−IR) and diffused reflectance (DR) UV−Vis spectra. The basal spacing (d〈sub〉〈em〉001〈/em〉〈/sub〉) of this inorganic-organic hybrid material, Fe(II)−Mt−L, was found to be 18 Å at room temperature. The XRD pattern shows the self-oriented (stacked) layer structure, which is independent of relative humidity. The TG−DTA curve shows the decomposition of interlayer complex at about 450 °C. The FTIR spectra show the prominent C−H bending for L around 720 cm〈sup〉−1〈/sup〉 and 845 cm〈sup〉−1〈/sup〉 in addition to other structural features of clay mineral. The DR UV−Vis spectra shows the absorption at about 510 nm, which is a characteristic value for [FeL〈sub〉3〈/sub〉]〈sup〉2+〈/sup〉 complex. The FE−SEM image and magnetic behaviour of the Fe(II)−Mt−L are compared with Fe(II)−Mt. The Fe(II)−Mt−L was heated upto 500 °C, and it was found that the structural integrity remained same until 350 °C as indicated by XRD, FTIR and TG-DTA. The d〈sub〉〈em〉001〈/em〉〈/sub〉 was reduced to 11.7 Å at about 400 °C and then the clay interlayer collapsed irreversibly to d〈sub〉〈em〉001〈/em〉〈/sub〉 of 9.6 Å. These hybrid materials are expected to show selective adsorption and catalytic property in organic (〈em〉ca.〈/em〉 Bigineli-type) reactions. As a first step, we have focused here only on preparation and characterization of these modified clay minerals by innovative approach.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303788-ga1.jpg" width="312" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 7 May 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science〈/p〉 〈p〉Author(s): Yong-Son Hong〈/p〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Javier Cuadros, Jana Schweigstillová〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phyllosilicate minerals have the potential to be used as indicators of past environmental conditions and climate. However, the appropriate use of this tool requires that the origin of the phyllosilicates be ascertained to correspond to the age under investigation, as mineralogical changes postdating it would lead to wrong conclusions. The soft sandstone of the Ashdown Formation (south-central and southeaster UK) contains fine-grained Al-phyllosilicates of limited interlayer expandability that have been described by other authors as vermiculite, smectite, interstratified illite-vermiculite and interstratified illite-smectite. The origin of these mineral phases is not yet agreed, with some authors reporting them as detrital and some as authigenic, generated by the weathering of detrital mica in the sandstone. In order to investigate whether or not these fine-grained minerals are detrital, four samples of the sandstone of variable softness were studied because they most likely had different clay content and because the different clay content could be possibly due to differential weathering. Investigation of mineralogy (X-ray diffraction), chemistry (bulk and SEM-EDS microanalysis) and rock fabric (image analysis of SEM micrographs) indicated that the sandstone consists of quartz, microcline, albite, anorthite, muscovite/illite, kaolinite, interstratified illite-smectite and smectite, where smectite layers expand only partially. Kaolinite is mainly detrital. Rock hardness was controlled by quartz abundance in the original sediment, not by later weathering. Alteration of the investigated sandstone samples after deposition was limited but reaction models are compatible with partial (〈10 wt%) alteration of muscovite/illite to illite-smectite and smectite, and of microcline and plagioclase to kaolinite. Analysis of mineralogical data of the fraction 〈2 μm of the Ashdown Formation from the literature is compatible with this interpretation and indicates that the range of muscovite/illite alteration to interstratified illite-smectite and smectite varied widely (0–45% in the 〈2 μm size fraction) depending on location and depth.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): S. Sahmani, M. Shahali, A. Khandan, S. Saber-Samandari, M.M. Aghdam〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work, bioactive nanoclay-TiO〈sub〉2〈/sub〉 (NC-T) bio-nanocomposite scaffolds containing different TiO〈sub〉2〈/sub〉 weight fractions are fabricated spacer for bone tissue engineering applications via the space holder technique using NaCl particles as the. The microstructure, surface morphology (porosity) and bioactivity potential of the manufactured bio-nanocomposite scaffolds are examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), energy dispersive spectroscopy (EDS), and inductively-coupled plasma optical emission spectroscopy (ICP-OES) techniques. The scaffold with optimized mechanical properties is predicted as NC-15wt%T with proper interconnected porosity and micro/macro pore size within the range of 1–2 (μm) and 3–5 (μm), respectively. Also, its mechanical properties including compressive strength, elastic modulus and crystallite size are extracted equal to 5.74 MPa, 438 MPa and 70–120 nm, respectively. The feasibility of the fabricated scaffolds for bioactive bone tissue engineering application (apatite deposition) is also evaluated using simulated body fluid (SBF) and physiological saline (PS) solutions. At the end, the nonlinear bending and vibration characteristics of an axially loaded beam-type bone implant made of the NC-T/NaCl bio-nanocomposite scaffolds are predicted analytically. In general view, the obtained results indicate that the NC-15wt%T/NaCl bio-nanocomposite scaffold may have excellent advantages for future research in bone regenerative applications.〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Zongshan Wu, Tianhu Chen, Haibo Liu, Can Wang, Peng Cheng, Dong Chen, Jingjing Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To availably utilize opal-palygorskite clay, dry beneficiation technique was applied to separate opal and palygorskite clay. Based on separated opal from opal-palygorskite clay, 4A zeolite was successfully synthesized by using a hydrothermal method. Box-Behnken was used to optimize Na〈sub〉2〈/sub〉O/SiO〈sub〉2〈/sub〉, H〈sub〉2〈/sub〉O/Na〈sub〉2〈/sub〉O and SiO〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 with cation exchange capacity (CEC) as the response value. The optimum parameters was determined to be Na〈sub〉2〈/sub〉O/SiO〈sub〉2〈/sub〉 = 1.0, H〈sub〉2〈/sub〉O/Na〈sub〉2〈/sub〉O = 40, and SiO〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 = 2.0, and CEC got the maximum of 2.99 mmol/(g·dry zeolite) under the conditions. The as-obtained 4A zeolite was characterized by using X-ray diffraction (XRD), thermo gravimetric analysis (TG), acid-base titration, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and then was applied to remove Hg〈sup〉2+〈/sup〉 from aqueous solution. The maximum removal capacity of Hg〈sup〉2+〈/sup〉 was 41.99 mg/g and adsorption equilibrium was obtained with contact time of 2 h. Effects of pH, ionic strength, temperatures, metal cations, strippant kinds and cycle times on removal behaviors of Hg〈sup〉2+〈/sup〉 onto 4A zeolite were investigated by batch experiments. The kinetics and isotherms of Hg〈sup〉2+〈/sup〉 adsorption fitted well by pseudo-second kinetic and Langmuir models. When Hg〈sup〉2+〈/sup〉-adsorbed 4A zeolite was desorbed using 1 mol/L NaNO〈sub〉3〈/sub〉 solution, the adsorption efficiency was maintained about 70% after four cycles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Priya P. Gurav, S.C. Datta, S.K. Ray, P.L. Choudhari, N. Ahmed〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Studies to evaluate the release threshold level of potassium in Vertisols (shrink-swell soils) in different agro-ecological regions of India and how that may help in K fertility interpretations are rare. Thus the objectives of this study were (i) to evaluate the K status of Vertisols through release threshold levels and (ii) to relate the findings with soil K release and fertilizer management. Three established soil series samples were collected from Vertisols of different agro-ecological regions of India. Release threshold level (RTL) was assessed after equilibrating soil with 0.01 M CaCl〈sub〉2〈/sub〉 solution having series of soil: solution ratio, after which the remaining amount of exchangeable K was extracted with 1 N NH〈sub〉4〈/sub〉OAc (pH 7). Total amount of K extracted (K〈sub〉T〈/sub〉 = K desorbed in CaCl〈sub〉2〈/sub〉 solution plus K extracted with 1 N NH〈sub〉4〈/sub〉OAc) remained more or less constant with decreasing K-level up to a certain value (say threshold value) below which K〈sub〉T〈/sub〉 increased sharply indicating K release from non-labile form. The threshold value in terms of K concentrations (Release Threshold Concentration) of Panjari, Nagpur, Maharashtra (Typic Haplusterts, Sub-humid dry), Teligi, Bellary, Karnataka (Sodic Haplusterts, Semi-arid dry) and Kheri, Jabalpur, Madhya Pradesh (Typic Haplusterts, Sub-humid moist) soils were 0.044–0.049, 0.034–0.062 and 0.043–0.11 mm, respectively. The high release threshold K levels in terms of concentration and activity ratio (AR) were observed in soils of Teligi and Kheri series as compared to soils of Panjari series due to high content of trioctahedral mica in the former two soils. The relationships between clay minerals, release threshold level, exchangeable potassium and non-exchangeable potassium determined by 1 N HNO〈sub〉3〈/sub〉 and sodium tetra-phenyl borate (NaBPh〈sub〉4〈/sub〉) have been discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Peng Zhang, Fujie Zhu, Xiaoling Tan, Wenqing Li, Shaonan Xu, Peiping Zhang, Cundi Wei, Shiding Miao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One-step synthesis of Ru/montmorillonite (Ru/Mt) without using any organic ligands has been successfully implemented from a gel system of RuCl〈sub〉3〈/sub〉-Na〈sub〉2〈/sub〉O-ZnO-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-SiO〈sub〉2〈/sub〉-F〈sup〉−〈/sup〉–H〈sub〉2〈/sub〉O, and the catalytic application was demonstrated in the hydrogenation of nitrobenzene (NB). The synthesized materials were characterized by X-ray diffraction, infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Due to the particular structure of which Ru(0)-nanoparticles were encapsulated by clay layers, the catalytic activity of Ru/Mt. was found to experience no significant deactivation after runs of reactions. The catalytic performance of Ru/Mt. was determined as a function of Ru loading amount with respect to NB. The conversion of NB to aniline was found to reach 99.42% within 2.0 h (P〈sub〉H2〈/sub〉 = 5.0 Pa; 〈em〉T〈/em〉 = 90 °C), and the turnover frequency was higher than activated carbon- or Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-supported- ruthenium catalysts (Ru/AC, Ru/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉). The method has its priority in getting pure clay supports, and high catalytic activity was obtained by avoiding the paramagnetic ions from natural clays.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical Abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304216-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Yi Wang, Xiaohe Liu, Ning Zhang, Guanzhou Qiu, Renzhi Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Active, stable and low-cost electrocatalysts are in high demand to replace the traditional noble metal catalysts towards efficient water splitting. Here we report a type of nickel-manganese (Ni–Mn) layered double hydroxide (LDH) with controllable doping content of cobalt as an oxygen evolution reaction (OER) electrocatalyst with excellent performance in alkaline media. Co-doped Ni–Mn LDH nanoplates were synthesized via a facile hydrothermal method. It was found that the doping content of cobalt significantly affected the OER activities. The best electrocatalyst was based on a doping ratio of 21.1% Co, exhibiting a low overpotential of ~310 mV at a current density of 10 mA cm〈sup〉−2〈/sup〉, a Tafel slope of ~59 mV dec〈sup〉−1〈/sup〉 as well as excellent stability. This work demonstrates a facile synthetic method of rationally doping transition-metal hydroxides to develop new OER electrocatalysts with remarkable performance in water splitting.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphic abstract〈/h5〉 〈div〉〈p〉Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Mn LDH nanoplates with tunable cobalt doping content could be successfully prepared via a simple hydrothermal method. The doping content of cobalt in Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Mn LDH nanoplates has a significant influence on their OER activities. The 21.1% Co-doped Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Mn LDH exhibited excellent OER efficiency realizing an overpotential of 310 mV, Tafel plot of 59 mV/decade and a stable operating potential without fluctuating above 5 mV for 9 h. This work demonstrates a facile synthetic method and doping strategy for exploring electrocatalysts with remarkable OER performance, which will promote the development of transition-metal based hydroxides as high-performance electrocatalyst for water splitting.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303429-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Xiujiang Pang, Yuan Liu, Li Chen, Yi Zhong, Zaifeng Li, Meng Liu, Shaoxiang Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉CaAl-LDH has its special application such as crystal seeds in mortar to improve the early strength. But it is hard to prepare pure phase CaAl-LDH by traditional coprecipitation method and to avoid the byproducts like aluminum hydroxide and calcium carbonate. In this paper, pure phase Ca〈sub〉2〈/sub〉Al-LDH nanosheets could be obtained by controlling R〈sub〉b/s〈/sub〉 (mole ratio between base and salt solution) of 1.5 using a T-type microchannel reactor. The so-obtained Ca〈sub〉2〈/sub〉Al-LDH nanosheets had a two-dimensional structure with lateral size of 30–100 nm and thickness of 2–3 nm. By correlating characterizations of pH titration with zeta potential, detailed information was obtained during the formation process of LDH prepared by the microchannel reactor and traditional coprecipitation, respectively. Tracking zeta potential of LDH prepared by microchannel reactor revealed that Ca〈sub〉2〈/sub〉Al-LDH nanosheets were formed through one-step reaction between salts and base solutions in microspace. While for the case of traditional coprecipitation method, results revealed LDH formed through three stages: Al(OH)〈sub〉3〈/sub〉 formation, mixing of trace Ca〈sup〉2+〈/sup〉 into Al(OH)〈sub〉3〈/sub〉, and their transformation into LDH. As a hardening accelerator for mortar, a dosage of only 0.35 wt % Ca〈sub〉2〈/sub〉Al-LDH nanosheets prepared using microchannel reactor exhibited greatly enhanced performances in both the early tensile strength and compressive strength of the mortar, which increased by 62% and 36%, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Carla G. Fonseca, Viviane S. Vaiss, Fernando Wypych, Renata Diniz, Alexandre A. Leitão〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Many important properties of the clay minerals such as montmorillonite (Mt) arise from their surface chemistry especially when this material is submitted to an acid activation process which will result in materials catalytically active for a variety of reactions. The acid activation preferentially occurs on the edge surfaces, in this sense 〈em〉ab initio〈/em〉 calculations were performed in order to determinate the most probable models for (010) and (110) surfaces in both pyrophyllite and Mt clay minerals, the edge stability, the initial stages of the acid activation process and the main acid sites present in the structures. The calculations predicted that the (110) edge surface is more stable than the (010) edge surface at pyrophyllite, on the other hand, at Mt the (010) surface has shown to be more stable, thus the pyrophyllite edge surfaces should not be used as representative models of Mt edge surfaces. The microstructural evolution of the Mt during the acid activation was investigated by 〈sup〉29〈/sup〉Si and 〈sup〉27〈/sup〉Al SSNMR simulations and these calculations could assist in the correct assignment of the silicon and aluminum chemical environments. The reactivity of the surfaces was evaluated and the calculations indicate that the acid character of the acid-activated Mt mainly comes from the H sites present in silanol and aluminol groups. These sites might be responsible for the catalytic activity of these materials.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Feng Peng, Donghui Wang, Dongdong Zhang, Huiliang Cao, Xuanyong Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the ability to host anions or neutral drugs, layered double hydroxide (LDH) are hot spots in the field of biomaterials. Intensive works so far only have focused on their application in surface modification or injectable medicine. Yet, little literatures report the potential of LDH as bone implants. In the present study, four types of LDH (Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al, Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe, Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al and Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe) were prepared via a coprecipitation method. Our results showed that the synthetic LDH powders can be pressed into discs in the absence of binder. The discs can maintain their shape after immersed in culture medium for 10 days, not including Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH disc. The elastic modulus of all discs was between 9 and 35 GPa, which was close to cortical bone (5–23 GPa). Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH and Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe LDH showed higher cytotoxicity than Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH and Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe LDH whether in the form of suspension or extract. Furthermore, even up to 10 mg/mL, the extract of Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH and Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe LDH showed no cytotoxicity, while cells were totally died in the extract of Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH and Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe LDH. Compared with cells, bacterial showed an even lower tolerance concentration to Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH and Zn〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe LDH. This study indicates that Mg-containing LDH show better cytotocompatibility, while Zn-containing LDH show better antibacterial property. With proper elastic modulus and controllable biological effect, LDH are promising to be used as bone implants.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Jiangyan Yuan, Jing Yang, Hongwen Ma, Shuangqing Su, Qianqian Chang, Sridhar Komarneni〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Synthesis of nano-muscovite has significant implications for applications such as electrical insulation, composite materials and paper-making. In this study, an energy-saving, efficient and sustainable route to synthesize muscovite from K-feldspar was developed by mimicking natural chemical weathering process of feldspar. Here, well-crystallized nano-muscovite of uniform flaky morphology with a thickness of 20–40 nm was obtained at 250 °C in just 18 h after treatment of K-feldspar under hydrothermal conditions. Moreover, additional potassium generated by the dissolution of K-feldspar into solution was collected as KNO〈sub〉3〈/sub〉. This is truly a green chemical process for the synthesis of muscovite and niter in a closed system as it not only conserved all the starting chemicals for reuse but also generated two useful by-products, niter and CaSiO〈sub〉3〈/sub〉.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303715-ga1.jpg" width="247" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Jie Dong, Qing Zhu, Qingyun Wei, Baohui Zheng, Shangbin Li, Junping Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Naturally rich clay minerals are receiving increasing attention recently in preparation of super anti-wetting coatings, superhydrophobic and superamphiphobic ones. Clay minerals are a class of very promising natural building blocks for constructing microstructures of the coatings. Clay minerals such as Palygorskite (Pal), kaolinite, halloysite nanotubes and montmorillonite have been used. However, the comparative study about the effects of source of clay minerals on properties of the coatings remains a gap to be filled. Here, the first comparative study about superamphiphobicity and stability of superamphiphobic coatings based on Pal from different sources was reported. The superamphiphobic coatings were fabricated by hydrolytic condensation of silanes in the presence of Pal followed by spray-coating the as-prepared dispersions onto substrates. Five Pal samples from Anhui, Jiangsu and Gansu Provinces of China were chosen, and their effects on superamphiphobicity and stability of the coatings were studied using various analytical techniques including scanning electron microscopy and X-ray photoelectron spectroscopy. The superamphiphobicity and stability depend on micro/nanostructures of the coatings, originating from the microstructures of Pal. The Pal sample from Anhui is more suitable for preparing superamphiphobic coatings than the others because of the higher Mg content and the higher aspect ratio of the Pal nanorods. The finding will shed light on the progress of the clay-based super anti-wetting coatings.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303405-ga1.jpg" width="248" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 167〈/p〉 〈p〉Author(s): Jin Li, Jun Cai, Lian Zhong, Huali Cheng, Han Wang, Qimin Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chitosan/montmorillonite intercalated composite (CTS/MMT) was used as an effective adsorbent for removal of reactive red 136 (RR136). Taguchi method attached grey relational analysis was applied to determine the optimal adsorption conditions, including pH, initial concentration of dye, temperature, adsorbent dosage and contact time, for achieving simultaneous maximization of removal percentage and adsorption capacity. The percentage contribution of each adsorption condition was determined in the analysis of variance and shown that the most effective parameter is initial concentration of dye. The optimal adsorption conditions were found in pH 3, initial concentration of dye 240 mg/L, temperature 20 °C, adsorbent dosage 0.4 g/L and contact time 135 min. Under the optimal condition, the removal percentages and adsorption capacity were 74.7% and 445.38 mg/g, respectively. The adsorption behaviors showed that the adsorption isotherms and kinetics were in best agreement with the Toth isotherm and Brouers-Weron-Sotolongo model, respectively. Applicability of mechanistic models exhibited that film diffusion and intra-particle diffusion were involved in the current adsorption processes and intra-particle diffusion was not the only rate-controlling step. CTS/MMT before and after adsorption were characterized through FT-IR, XRD and SEM. The results indicated that the RR136 adsorption process was not only surface adsorption but intercalation, and 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉OH, 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉CONH〈sub〉2〈/sub〉, 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉NH〈sub〉2〈/sub〉 and Si〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O group of CTS/MMT were involved in the adsorption process. Moreover, the desorption and regeneration experiments revealed CTS/MMT showed excellent adsorption performance even after 15 adsorption-desorption cycles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Xiufang Zhu, Linzhi Zhai, Lijing Zhang, Jiadong Zhang, Xuemei Liu, Jie Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous palygorskite (Pal) was mixed with Ho〈sub〉0.9〈/sub〉Sr〈sub〉0.1〈/sub〉Cr〈sub〉0.5〈/sub〉Fe〈sub〉0.5〈/sub〉O〈sub〉3-δ〈/sub〉 (HSCF) perovskite to prepare a novel cathode material for SOFC due to large specific surface area and nano-scaled internal channels. Calcination of HSCF was preceded under 1000 °C by Thermogravimetry and differential scanning calorimetry techniques (TG-DSC) and X-ray diffraction (XRD) analysis. Field emission scanning electron microscopy (FESEM) and IR manifested that Pal was mixed homogeneously with HSCF. Brunauer-Emmett-Teller (BET) analysis proved that surface areas of cathode increased from 0.18 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉 to 4.23 m〈sup〉2〈/sup〉g〈sup〉−1〈/sup〉after mixing with palygorskite. In addition, the performances of the single cell (NiO-GDC|GDC|HSCF-GDC and NiO-GDC|GDC|HSCF-Pal-GDC) were also measured at 450–550 °C when the 99% H〈sub〉2〈/sub〉 and ambient air were fuels of anode and cathode, respectively. Corresponding the maximum power density were 14.32 mW·cm〈sup〉−2〈/sup〉 and 28.43 mW·cm〈sup〉−2〈/sup〉 at 500 °C. When the single cell operating temperature was raised to 550 °C, the performance of single cell NiO-GDC|GDC|HSCF-GDC continues to enhance, while another ome decreased sharply. BET values of the cathode with mixing Pal after cell test declined from 4.23 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉 to 0.11 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉, which indicated the collapsing of the pores in Pal at the cell operating temperature and impeded the performance of the cell. The operating temperature of the single cell after mixing Pal in electrode couldn't exceed 500 °C. The electrochemical impedance spectra (EIS) was also used to analysis the factors influencing cell performance. Therefore, HSCF-Pal as a promising cathode can be used as low temperature solid oxide fuel cell.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Xing Su, Biqiong Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fully swollen montmorillonite/alginate/Ca〈sup〉2+〈/sup〉 (Ca〈sup〉2+〈/sup〉-MtAlg) nanocomposites with a specific chemical composition are expected to show well-ordered microstructure, excellent mechanical properties, unique optical properties and solvent sensitivities. Inspired by nacre, Ca〈sup〉2+〈/sup〉-MtAlg nanocomposite hydrogel films with high montmorillonite mass contents (≥ 20%) were synthesised by solution casting, followed by subsequent ionic crosslinking. The fully swollen Ca〈sup〉2+〈/sup〉-MtAlg nanocomposite films were mechanically flexible and stable in water. By regulating the relative content of alginate and Mt, it was possible for the hydrogel films to reach a high tensile strength of 28 MPa. Ca〈sup〉2+〈/sup〉-MtAlg hydrogel films also showed acceptable transparency and high efficiency in blocking ultraviolet light. Furthermore, they demonstrated solvent sensitivity; the hydrogels lost water in either methanol or acetone, the one with an Mt/Alg mass ratio of 1:4 coiled seriously in acetone while those with a lower mass ratio were more stable in either methanol or acetone. Overall, Ca〈sup〉2+〈/sup〉-MtAlg nanocomposite hydrogel films have the potential for use in stimuli-responsive load-bearing biomedical applications, skin care and beyond.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303442-ga1.jpg" width="396" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Shahrzad Sadri, Bruce B. Johnson, Maika Ruyter-Hooley, Michael J. Angove〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nortriptyline (NT) is a tricyclic antidepressant in common use in many countries. Its presence in drinking water indicates that current wastewater treatment practices fail to remove it effectively from effluents with consequent adverse effects on aquatic organisms. Since mineral surfaces readily remove many organic substance from effluent streams, this research sought to study the adsorption of NT on montmorillonite, kaolinite and gibbsite. Adsorption edge and isotherm experiments were performed to determine the relative effectiveness of the three substrates for NT removal, and X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used in order to gain an understanding of the mode of adsorption. Adsorption of NT on all three substrates was effectively independent of pH in the range from 3 to 12. Both montmorillonite and kaolinite proved to be excellent adsorbents of NT with maximum adsorption capacities of 19.3 and 6.4 μmol m〈sup〉−2〈/sup〉 respectively at pH 6.0, but gibbsite adsorbed relatively little. The XRD and ATR-FTIR results indicated that NT formed as a multilayer on montmorillonite with no evidence of intercalation. Both electrostatic and hydrophobic interactions appeared to play important roles in the adsorption.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Xiaoyu Li, Kang Peng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A spatial confinement effect of CdS nanoparticles in mesoporous alumina, which is synthesized through evaporation-induced self-assembly (EISA) method, post-impregnation approach and microwave irradiation process, was investigated to verify the enhanced catalytic activity and stability with less aggregation of CdS crystallites during decoloration of organic dyes under visible-light irradiation. In this work, we utilize inexpensive natural clays for preparing mesoporous alumina via evaporation-induced self-assembly method, and used as the host for confining CdS nanoparticles to suppress the crystallite growth and aggregation. The loading amount and grain size of CdS nanoparticles significantly altered catalytic activity and stability. CdS clusters confined inside the mesoporous channels provided abundant reactive sites for photocatalytic reaction through spatial confinement effect, quantum size effect and sulfide-support interaction, thus greatly enhancing the reaction activity. CdS/MAl composites have large special surface area, strong visible light absorption and high quantum yields. CdS/MAl-25 photocatalyst has exhibited remarkably enhanced visible light photoactivities as compared to other catalysts, and the overall decoloration rate was up to 97.5% after visible light irradiation for 60 min. The CdS/MAl composites exhibit potential applications in the wastewater treatment under visible light irradiation.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical Abstract〈/h5〉 〈div〉〈p〉Mesoporous alumina from natural clays for confining CdS nanoparticles (CdS/MAl) were successfully prepared through evaporation induced self-assembly, post-impregnation and microwave irradiation as a novel photocatalyst for organic pollutants removal.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303818-ga1.jpg" width="307" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Junhua Zhang, Zhaoli Yan, Liangjie Fu, Yi Zhang, Huaming Yang, Jing Ouyang, Deliang Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Acid-activated sepiolite nanofibers (ASep) were organically modified with (3-aminopropyl) triethoxysilane (APTES) to produce the amino-functionalized nanofibers (NH〈sub〉2〈/sub〉-ASep). Due to the amino groups, highly dispersed silver nanoparticles (AgNPs) were assembled on the surface of NH〈sub〉2〈/sub〉-ASep by a simple chemical reduction approach, and the AgNPs were smaller than those directly deposited onto ASep surface. The as-synthesized Ag/NH〈sub〉2〈/sub〉-ASep nanofiber catalysts exhibited an excellent catalytic activity in the reduction process of 4-nitrophenol to 4-aminophenol with full conversion within 150 s in the presence of NaBH〈sub〉4〈/sub〉 as the reductant. The results indicated that Ag/NH〈sub〉2〈/sub〉-ASep nanofiber catalysts exhibited excellent catalytic activities because the highly dispersed of small-sized AgNPs were exposed on the surface of highly dispersed nanofibers with amino functional groups, allowing effective contact with the reactants and catalysis of the reaction. Moreover, the Ag/NH〈sub〉2〈/sub〉-ASep nanofiber catalysts are stable and easy to use for the catalytic reaction due to their one-dimensional nanofiber structure with functional amino groups.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304253-ga1.jpg" width="226" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 174〈/p〉 〈p〉Author(s): Bhojaraj, Pramod Harley, Michael Rajamathi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several aldehydes undergo disproportionation into corresponding acids and alcohols (Cannizzaro reaction) over calcined hydrotalcite, magnesium aluminum layered double hydroxide (LDH), in water. The reactions are slow and ~10% conversions were achieved after stirring for 24 h at room temperature. The mixed metal oxide obtained on calcination of the LDH gets hydrated to a meixnerite-type phase, which provides the necessary basicity for the Cannizzaro reaction. The calcination temperature of LDH, if it is above the decarbonation temperature, has no appreciable effect on the outcome of the reaction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 174〈/p〉 〈p〉Author(s): L. Morales, E. Garzón, E. Romero, P.J. Sánchez-Soto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The objective of the present study is to develop a biotechnological tool for a new application of clay phyllites as stabilized materials in linear works replacing chemical stabilizer (e.g. cement or lime) by natural cement, formed by precipitated calcium carbonate generated by microorganisms of the 〈em〉Bacillaceae〈/em〉 family (〈em〉Bacillus pasteurii〈/em〉). Part of the development process conducting a chemical and mineralogical characterization and an examination of physical and hydromechanical properties. The results of this study show that the effect of bacteria on clay phyllites increases the calcium carbonate content, specific surface area and plasticity values. These increased values are caused by the addition of a non-plastic component to clay phyllites resulting in a more aggregated structure through the precipitation of calcium carbonate from the bacteria, ultimately filling the pores of this material. Microbiological treatments on clay phyllites tends to aggregate the original particles, creating aggregates that are partially associated with the formation of calcium carbonate. Said process is influenced by the curing and compaction procedures conducted on samples, which also cause breakage of carbonated structures formed during treatment. As a result of this breaking process of aggregates, some compaction energy is lost and the treated samples do not reach the maximum dry density of the natural state for the same level of compaction energy applied. Treated samples display a slightly larger friction angle with no cohesion, consistent with filling properties and denser condition. Compressibility is consistently lower than that of the natural state. Comparison of collapse data shows that the occurrence and amount of collapse are controlled by the as-compacted dry density. It is also determined that higher compaction effort is even more effective than increasing the amount of bacteria introduced to stabilize the sample for the filling of pores (size ranges 3–50 μm) with calcium carbonate. However, the post-ageing compaction destroys the initial binding/cementation effect.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): M. Frías, R. Vigil de la Villa, R. García, S. Martínez-Ramírez, L. Fernández-Carrasco〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The use of industrial waste as a cement addition often changes the composition and development of the hydrated phases and with them matrix performance and durability, in particular at later ages. The effect of the presence in blended cement of 20% to 50% kaolinite based activated carbon waste (ACW) on paste hydration has been characterized by means of XRD, SEM/EDX, TG/DTG, NMR and FTIR to identify and monitor the mineralogical phases forming in materials at ages of up to 180 d. The results showed that the main reaction products forming in the first 7 d included C-S-H gels, C〈sub〉4〈/sub〉ACH〈sub〉12〈/sub〉 and C〈sub〉4〈/sub〉AH〈sub〉13〈/sub〉 (hydroxy-AFm〈sub〉)〈/sub〉. Whilst monocarboaluminate (Mc) content declined with rising percentages of ACW, the amount of hexagonal phase hydroxy-AFm rose. Then microstructure of the C-S-H gels developing in the OPC and the 50% additioned paste differed. Compact C-S-H gel plates, and phyllosilicate-like laminar spongy microplates with high polymerised C-S-H gel formed in the blended cement paste.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Zahra Amini, Morteza Asghari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Supported Mixed Matrix Membrane (SMMM) Polyether block amide/nanoclay (PEBA/Cloisite 30b), based on Polyacrylonitrile on nonwoven Polyester (PAN/PE), was fabricated by the spin coating method, following optimization of fabrication conditions for Single-Layer Mixed Matrix Membranes (SLMMMs). Cloisite 30b is a type of montmorillonite modified from nanoclays family. The fabricated membranes were examined structurally through The X-ray Diffraction (XRD), The Field Emission Scanning Electron Microscopy (FESEM), The Fourier-transform infrared spectroscopy (FTIR), and The Atomic force microscopy (AFM) analyses, and evaluated operationally by conducting permeability tests of the pure gases of CO〈sub〉2〈/sub〉, CH〈sub〉4〈/sub〉 and N〈sub〉2〈/sub〉. The effect of different Cloisite 30b loadings and the varying pressures on the gas separation performance of the membranes was investigated. Elevation of the loading up to 0.2 wt% Cloisite 30b increased the permeability and the selectivity, whereas further increase up to 1 wt% reduced the permeability and selectivity. After an increase in pressure from 4 to 14 bar, an elevated permeability and selectivity was observed. The membrane with a Cloisite 30b loading of 0.2 wt% had the best performance in the separation of the pure gases of CO〈sub〉2〈/sub〉, CH〈sub〉4〈/sub〉, and N〈sub〉2〈/sub〉 such that the permeability of CO〈sub〉2〈/sub〉, along with the selectivity of CO〈sub〉2〈/sub〉/N〈sub〉2〈/sub〉, and CO〈sub〉2〈/sub〉/CH〈sub〉4〈/sub〉 had increase of about 55.55%, 26.45% and 38% in comparison with the Single Layer Neat Membrane (SLNM). The permeability of CO〈sub〉2〈/sub〉, the selectivity of CO〈sub〉2〈/sub〉/N〈sub〉2〈/sub〉, and the selectivity of CO〈sub〉2〈/sub〉/CH〈sub〉4〈/sub〉 of SMMM with a Cloisite 30b loading of 0.2 wt% also indicated an increase of about 364%, 18% and 47.8% in comparison to the Supported Neat Membrane (SNM). Furthermore, CO〈sub〉2〈/sub〉 permeability through SMMM with cloisite30b loading of 0.2 wt% indicated a growth of about 562.5% in comparison to SLMMM with the same loading.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304241-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Fengyan Xiao, Yawei Qin, Ning Wang, Dawei Pan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Noble metals supported on substrates have been proven as highly efficient catalysts for the reduction of nitro-compounds. However, their large-scale applications are still limited by the problems of fouling and transport during the mass production process. Herein, we first fabricated a spherical montmorillonite (Mt) substrate via spray drying technique, followed by the deposition of Au NPs through polydopamine chemistry to synthesize spherical Au nanoparticles supported Mt (Au@Mt) microspheres. The Au loading is 14.5 wt%, whereas the specific surface area of the Au@Mt microspheres is 47.3 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉, endowing the prepared Au@Mt microspheres with excellent catalytic activity to the reduction of 4-nitrophenol (4-NP) in the presence of NaBH〈sub〉4〈/sub〉 with the optimized apparent reduction rate constant higher than 1.05 min〈sup〉−1〈/sup〉. Furthermore, the microspheres can be easily recycled with self-sedimentation without any devices involved and showed excellent stability and recyclability for at least 20 cycles without almost unchanged spherical morphology and catalytic performance. Our straightforward strategy to solve the issue of the mass production process through granulation of amorphous nanomaterial substrate facilitates the practical application of these catalysts in the reduction of nitro-compounds.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304150-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Chandni Puri, Gajjala Sumana〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, graphene oxide intercalated montmorillonite nanocomposites were prepared by a facile chemical route and then used for the adsorption of crystal violet dye from contaminated water. Structural characterization of the nanocomposites were performed using Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, zeta potential, X-ray diffraction, specific surface area and pore volume measurements. The isothermal data obtained using batch adsorption technique were fitted using Langmuir and Freundlich equations and it was found that the experimental data is well described by the Langmuir isotherm model with a very high adsorption capacity of 746.27 mg g〈sup〉−1〈/sup〉. The kinetics of the adsorption process showed rapid dynamics and conformed to pseudo-second-order model with a correlation coefficient of R〈sup〉2〈/sup〉 〉 0.99. The influence of interaction time and initial dye concentration on the adsorption efficiency were also investigated. Additionally, thermodynamic studies revealed that the adsorption process was spontaneous and endothermic. Further, the results indicated that the synthesised nanocomposites adsorb crystal violet dye efficiently (∼96%) with a small decrease in removal efficiency even after five cycles of adsorption and could be employed in wastewater treatment for the removal of cationic dyes.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉〈div〉〈p〉Graphical abstract〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304125-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Alberto Viani, Radek Ševčík, Marie-Sousai Appavou, Aurel Radulescu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure of extruded fired-clay bodies in the interval 800–1100 °C has been investigated with small angle neutron scattering. The evolution of the retrieved pore size distribution is compatible with the coarsening of the pore network with increasing temperature. The analysis of the scattering curves in combination with results of electron microscopy, indicated a multiscale nature for the pore-matrix microstructure. A structural parameter obtained from the analysis of the scattering curves, is proposed as indicator of maximum firing temperature through the implementation of a linear calibration curve. Such method has been successfully tested on a material of industrial production and can be considered of interest for the production of custom made replacement materials in the conservation of cultural heritage or for the characterization of the manufacturing process of archaeological fired-clay objects. Textural features originated by the forming process of extrusion have been detected as anisotropy of the pore network. They are still present above 1000 °C and, because of the use of screw extrusion, they are observed in both sections cut parallel and perpendicular to the direction of extrusion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Qi Zhou, Junlong Huang, Xing Zhang, Yun Gao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To overcome the inherent defect of particle adsorbent that difficult to be recycled from waterbody, a new adsorbent was successfully prepared based on the surface polypyrrole (PPy) functionalized sepiolite fiber (SEP), with properties of magnetism and floatation. This adsorbent can be recovered easily from water surface by a magnet. The resultant MSEP/PPy retains the feature of sepiolite fiber template, along with a large surface area to have more surface adsorption sites. Batch experiment shows the experiment data is in good agreement with the pseudo-second order kinetic and Langmuir isotherm model. The adsorption mechanism reveals that the ion exchange occurs between Cl〈sup〉−〈/sup〉 and Cr(VI), followed by the reduction of Cr(VI) to Cr(III) via the surface PPy moiety. Additionally, most of the adsorption capacity of the adsorbent can be maintained in the cyclic regeneration, ranging from 87.93 to 58.36 mg/g even in the incomplete desorption.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304307-ga1.jpg" width="333" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Tao Wu, Zhifen Wang, Yanhua Tong, Yongya Wang, Luc R. Van Loon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The interlayer cation of bentonite has obviously influence on the diffusion behavior of radionuclides. The diffusion behavior of Re(VII) in Na〈sup〉+〈/sup〉- and Ca〈sup〉2+〈/sup〉-bentonites was investigated by a through-diffusion method at bulk dry densities from 1000 kg/m〈sup〉3〈/sup〉 to 1800 kg/m〈sup〉3〈/sup〉. A modified multi-porosity model (APM), which subdivided the porosity into the interlayer porosity (〈em〉ε〈/em〉〈sub〉〈em〉il〈/em〉〈/sub〉), the diffuse double layer porosity (〈em〉ε〈/em〉〈sub〉〈em〉ddl〈/em〉〈/sub〉) and free layer porosity (〈em〉ε〈/em〉〈sub〉〈em〉free〈/em〉〈/sub〉) in compacted bentonite, is employed to describe the distribution of the three porosities as a function of the bulk dry density and to explain the lower effective diffusion coefficient (〈em〉D〈/em〉〈sub〉〈em〉e〈/em〉〈/sub〉) and accessible porosity (〈em〉ε〈/em〉〈sub〉〈em〉acc〈/em〉〈/sub〉) of Re(VII) in Na〈sup〉+〈/sup〉-bentonite compared to that in Ca〈sup〉2+〈/sup〉-bentonite. With increasing bulk dry density, 〈em〉ε〈/em〉〈sub〉〈em〉acc〈/em〉〈/sub〉 decreased, leading to a decrease of 〈em〉D〈/em〉〈sub〉〈em〉e〈/em〉〈/sub〉 for Re(VII). 〈em〉ε〈/em〉〈sub〉〈em〉ddl〈/em〉〈/sub〉 and 〈em〉ε〈/em〉〈sub〉〈em〉il〈/em〉〈/sub〉 are both related to the montmorillonite bulk dry density. Moreover 〈em〉ε〈/em〉〈sub〉〈em〉ddl〈/em〉〈/sub〉 is also related to the external surface area (〈em〉A〈/em〉〈sub〉〈em〉ext〈/em〉〈/sub〉) and the ionic strength. APM was successful in reproducing trends of 〈em〉ε〈/em〉〈sub〉〈em〉acc〈/em〉〈/sub〉 data for Re (this work), 〈sup〉35〈/sup〉Cl and 〈sup〉125〈/sup〉I (data from the literature) as a function of the bulk dry density. Compared to Ca〈sup〉2+〈/sup〉-bentonite, Na〈sup〉+〈/sup〉-bentonite had higher 〈em〉ε〈/em〉〈sub〉〈em〉il〈/em〉〈/sub〉 and 〈em〉ε〈/em〉〈sub〉〈em〉ddl〈/em〉〈/sub〉 at the same compaction, indicating a less proportion of large pores. After combing with Archie's law, the dependency of 〈em〉D〈/em〉〈sub〉〈em〉e〈/em〉〈/sub〉 on bulk dry density was reproduced with a cementation factor of 2.2 and 2.6 for Na〈sup〉+〈/sup〉- and Ca〈sup〉2+〈/sup〉-bentonites, respectively.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303892-ga1.jpg" width="302" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): E.C. dos Santos, W.P. Gates, L. Michels, F. Juranyi, A. Mikkelsen, G.J. da Silva, J.O. Fossum, H.N. Bordallo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biocompatible encapsulated drug delivery materials are highly desired as they provide for controlled release of bioactive agents, thereby improving the effectiveness of medical treatments. Some of the key properties of better materials for drug delivery include high adsorptive capacity, which can be realized by smectites, a family of clay minerals. Here the influence of pH on encapsulation of the bioactive molecule ciprofloxacin (CIPRO), an antibiotic, by fluorohectorite (FHt), a synthetic smectite, was investigated. Aspects of the clay structure itself were also investigated. By means of X-ray powder diffraction (XRD), thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TGA/FTIR) and inelastic neutron scattering (INS), it is demonstrated that the capture of ciprofloxacin is more efficient at acidic pH. Geometric considerations based on the XRD results and mass calculations based on the TGA results provided evidence that at acidic pH, the CIPRO-FHt complex contained one CIPRO molecule per unit cell, while at neutral pH the CIPRO content was about half, despite having similar interlayer volume available. Finally it is shown that adsorption of CIPRO by FHt facilitated removal of residual water from the interlayer, providing additional evidence that intercalation is the main adsorptive mechanism at acidic pH. These results lead to a deeper understanding concerning the capture of amphoteric drug molecules by smectites, as well as concerning their molecular interactions, which may lead to more feasible application of clay minerals as a carrier for drug molecules.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Huali Xie, Xuejun Lai, Hongqiang Li, Xingrong Zeng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Realizing the high efficiency of halogen-free flame retardant is one of the biggest challenges and the most urgent issues in the development of high performance polypropylene (PP). Coupling the catalytic carbonization and free-radical quenching mechanism is proposed to be an efficient method to address this issue. In this work, a functionalized zirconium phosphate (F-ZrP) with good catalytic carbonization capability was synthesized, and was combined with N-alkoxy hindered amine (NOR) to flame-retard PP. The composition showed high flame-retardant efficiency. When the content of NOR, F-ZrP and ammonium polyphosphate were 0.2 wt%, 4.95 wt% and 14.85 wt%, respectively, the flame retardant PP reached a limiting oxygen index of 36.0% and achieved a UL-94 〈em〉V〈/em〉-0 rating. Meanwhile, the peak heat release rate, average heat release rate, total heat release, peak smoke production rate and total smoke production were declined by 95.6%, 90.6%, 73.3%, 93.5% and 80.6%, respectively. It revealed that F-ZrP formed closed micron-scale char-cages 〈em〉via〈/em〉 interfacial carbonization. In the char-cages, the nitroxyl radicals generated by NOR efficiently quenched the active free-radicals produced by PP and induce their cyclization reaction. Under the further catalytic effect of ZrP, graphitized crystalline char with extraordinary thermostability and barrier effect was generated quickly and protected the polymer from burning.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Ahmed M. Zayed, Mahmoud S.M. Abdel Wahed, Essam A. Mohamed, Mika Sillanpää〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The role of organic matters (OM) of some Egyptian clay in Methyl Orange (MO) adsorption from aqueous solutions was tested for the first time. To elaborate this role, the raw Organic Matters-Rich Clays (OMRC) was calcinated at 500 °C/4 h to remove their associated OM by oxidation. Then the MO removal efficiency by both OMRC and its calcinated derivative (COMRC) was tested at different experimental parameters. The adsorption of MO by the studied adsorbents was pH- and time-dependent process and the equilibrium was attained after 60 min. The pseudo-second-order model with high determination coefficients (R〈sup〉2〈/sup〉 〉 0.999) fitted well the adsorption kinetics, while the intra-particle diffusion was not the rate governing step in MO adsorption by both adsorbents. The MO adsorption characteristics revealed that equilibrium data of OMRC and COMRC fitted well to the Freundlich and Langmuir models, respectively. Electrostatic interaction was the primary but not the only governing mechanism for MO adsorption by the investigated adsorbents; participation from hydrogen bonding mechanism was involved, with some preference for COMRC. The superiority of OMRC over COMRC in MO adsorption can be attributed to the involvement of oxygen- and nitrogen-bearing groups of both OM and clay minerals in the adsorption process on the contrary of COMRC in which only oxygen-bearing groups of the clay minerals were incorporated.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Feng Zhou, Huaibing Song, Hongquan Wang, Sridhar Komarneni, Chunjie Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several nitrogen-doped TiO〈sub〉2〈/sub〉/Sepiolite (N-TiO〈sub〉2〈/sub〉/Sep) photocatalysts were prepared via microwave-hydrothermal treatment using four different types of nitrogen sources: ammonium hydroxide, urea, ethylenediamine and triethylamine. The obtained nanocomposites were characterized by using XRD, TEM, BET, XPS and UV–vis techniques. The results revealed that the chemical and morphological properties of the nanocomposites were significantly dependent on the nitrogen source. The interstitial N doping occurred in the form of N-O-Ti-O and the surfaces of the samples were modified by carbon species from dopants. As compared to that of the undoped sample, N-doped samples exhibited a red shift in the band gap transition. The results of simulated solar light photocatalytic activities demonstrated that NTS-EDA exhibited better photocatalytic activity than singly N-doped (i.e., no carbon) or undoped TiO〈sub〉2〈/sub〉/Sep sample. The enhanced solar-light activity is attributed to the low band gap energy with N-doping, the high adsorption capacity and uniform distribution of titania nanoparticles with sepiolite as support, and the appropriate carbon content of the dopants.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Isabel González, Antonio Romero-Baena, Emilio Galán, Adolfo Miras, José Carlos Castilla-Alcántara, Paloma Campos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The characterization of ceramic materials from archaeological sites is of great importance to learn about the human traditions and regional History. In this work, 12 pieces of ceramics of the Cuatrovitas Archaelogical Site (Bollullos de la Mitación, Seville, Spain) were studied to approach the provenance of the raw material and the firing temperature. In addition, raw materials, from possible sources areas used for the manufacture of those ceramics, were also studied. Mineralogical characterization by XRD and chemical analyses of major, trace and rare earth elements were performed on both raw and ceramic materials. Thin sections, SEM-EDS analyses and micro-XRF mapping were carried out to complete the mineralogical and chemical characterization. The results show that there are two types of ceramic materials, probably prepared by mixtures of different clays and sandy materials. A feasible source area for those raw materials could be the alluvial of the Guadiamar River. According to the mineralogy of the high-temperature phases found in the ceramic pieces, two firing temperatures can be approached: one at 800–850 °C owing to the presence of calcite, and another at 900–950 °C because of the presence of diopside and gehlenite.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Milan Kracalik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Clay-polymer nanocomposites exhibit complex rheological behavior due to physical and also possibly chemical interactions between individual phases. Up to now, rheology of clay-polymer nanocomposites has been usually described by evaluation of complex viscosity curve (shear thinning phenomenon), storage modulus curve (G´ secondary plateau) or plotting parameters characterizing damping behavior (e.g. Van Gurp-Palmen-plot, Cole-Cole plot). On the contrary to evaluation of damping behavior, new approach – based on evaluation of rigidity behavior – was tested, where the values of cot δ were calculated and called as „storage factor“, analogically to broadly used loss factor. Afterwards, values of storage factor were integrated over measured frequency range and called as “cumulative storage factor”. In this contribution, clay-PET nanocomposites with different organoclays have been prepared and characterized by both conventional as well as novel analysis approach. Rheological results have been supported by 〈span〉〈/span〉AFM micrographs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Anna S. Semenkova, Mariia V. Evsiunina, Parveen K. Verma, Prasanta K. Mohapatra, Vladimir G. Petrov, Irina F. Seregina, Mikhail A. Bolshov, Victoria V. Krupskaya, Anna Yu. Romanchuk, Stepan N. Kalmykov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The sorption of Cs〈sup〉+〈/sup〉 onto raw Kutch clay (India) over a wide range of concentrations and pH levels was studied and compared with its sorption onto the well-studied FEBEX clay (Spain). The principal clay mineral in both samples is montmorillonite. Non-linear sorption isotherms were measured for both clays. The shapes of the isotherms prompted the use of a two-site exchange thermodynamic model to describe the experimental data. However, differences in the highly selective sorption sites (Type 1) were observed for the two studied clays. It was found that the presence of different cations (H〈sup〉+〈/sup〉, Ca〈sup〉2+〈/sup〉, Mg〈sup〉2+〈/sup〉, etc.) in solution affected the sorption of Cs〈sup〉+〈/sup〉. A model accounting for the competition process was developed for predicting the behavior of the raw clay in complex solutions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 167〈/p〉 〈p〉Author(s): Xin Wei, Yuemiao Liu, Junhua Dong, Shengfei Cao, Jingli Xie, Nan Chen, Fang Xue, Changgang Wang, Wei Ke〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In China-Mock-Up, the transition of water conditions in bentonite and its influence on the corrosion behavior of four low carbon steel electrochemical sensors buried in bentonite along horizontal direction were investigated by in situ electrochemical impedance spectroscopy (EIS) with the infiltration of groundwater from outside to inside. The results show that in the initial stage of EIS measurement, water in bentonite around the electrochemical sensors from outside to inside is hygroscopic water and chemical bonding water successively. With increasing time, water in the outer bentonite transforms from hygroscopic water to free water. Meanwhile, water in the inner bentonite transforms from chemical bonding water to hygroscopic water. As water in bentonite exists as the chemical bonding water, the equivalent circuit can be described as a pure capacitor, which does not cause the corrosion of low carbon steel. When water in bentonite exists as hygroscopic water, it can be described as a circuit consisting of two leakage capacitors in series, which causes the slight corrosion of the steel. While, in the presence of free water, the equivalent circuit can be described as a free water resistance and two leakage capacitors in series, which causes the serious corrosion of the steel.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Manuel Sánchez-Marañón, Javier Cuadros, Joseph R. Michalski, Manuel Melgosa, Vesselin Dekov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A range of phyllosilicate compositions have been detected spectroscopically on Mars, but the largest fraction by far corresponds to clay minerals rich in Fe and Mg. Given that most of our understanding of Martian clays comes from remote sensing data, it is critically important to explore the details of how compositional variation affects spectral features of phyllosilicates. The greatest efforts have focused so far on near-infrared (NIR) spectroscopy. Recently, ambiguities have been detected in the NIR spectra of 2:1 phyllosilicates with intermediate Fe〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Mg content that preclude mineral and chemical discrimination. Such ambiguities highlight the relevance of exploring the visible spectral range as a complementary tool to characterize Martian phyllosilicates precisely. This article reports the investigation of laboratory reflectance spectra (330–800 nm) from 34 Earth analogues of Martian phyllosilicates with a wide range of Mg〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Fe composition, including nontronite, celadonite and saponite end-members, as well as interstratified glauconite-nontronite, talc-nontronite, and talc-saponite. The spectra indicated the presence of Fe(III) by absorption modulations and a decrease in total reflectance, especially in samples with tetrahedral Fe(III). Absorption bands at 370 and 420 nm were diagnostic of octahedrically and tetrahedrally coordinated Fe(III), respectively. Band amplitudes in the second derivative of the Kubelka-Munk function correlated positively with Fe(III) content (〈em〉R〈/em〉〈sup〉2〈/sup〉 〉 0.8). Standard color analyses of the visible reflectance spectra under the CIE illuminant D65 indicated that the CIELAB color parameter 〈em〉a〈/em〉*〈sub〉10〈/sub〉 was positively correlated with tetrahedral Fe(III), 〈em〉b〈/em〉*〈sub〉10〈/sub〉 was positively correlated with octahedral Fe(III), and 〈em〉L〈/em〉*〈sub〉10〈/sub〉 was negatively correlated with Fe(III) in both structural sites. Because Fe(II) was in relatively low amount, it did not provide clear spectral evidence. Multiple regression models using the amplitude of the diagnostic absorption bands predicted well absolute Fe content in the phyllosilicates (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.89) and the ratio Fe/(Fe + Mg + Al) (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.84). CIELAB color parameters improved the prediction of total Fe (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.92) and the ratio Fe/(Fe + Mg + Al) (〈em〉R〈/em〉〈sup〉2〈/sup〉 = 0.93). Application of these analyses to Martian data has challenges set by Fe oxide dust coating and spatial and spectral resolution. However, these results mark an avenue to develop testable tools using visible-wavelength spectral data from both satellite and lander probes to help establishing Fe content and mineral identification of Martian phyllosilicates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Chao-Rong Chen, Hong-Yan Zeng, Sheng Xu, Jia-Chao Shen, Guo Hu, Run-Liang Zhu, Jin-Ze Du, Yun-Xin Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cadmium sulfide (CdS) is an excellent visible light responsive material for the appropriate band gap, but the high electron-hole recombination and particle aggregation of CdS seriously limited its practical application in photocatalysis. In this work, the CdS/ZnAlO heterostructures photocatalyst was synthesized via a facile hydrothermal method. The structural characterizations showed that the particles aggregation of CdS and the separation of photogenerated electron-hole pairs were obviously improvement. The CdS/ZnAlO composite showed the highest photocatalytic activity for Cr(VI) reduction under visible light within 120 min. The enhanced photocatalytic activity might be attributed to the synergistic effect of the effective separation of photogenerated electron-hole and the adsorption of Cr(VI) on the interface of the catalyst. In addition, the possible mechanism of Cr(VI) reduction over CdS/ZnAlO was also proposed. The present work is devoted to synthesise a high efficient and stable photocatalyst for Cr(VI) contaminated wastewater treatment.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical Abstract〈/h5〉 〈div〉〈p〉The CdS/ZnAlO heterojunction photocatalyst was designed and prepared to improve the charge transfer and the particle aggregation of CdS, which demonstrated highly efficient photocatalytic activity and stability for Cr(VI) reduction under visible light irradiation.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718303831-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 165〈/p〉 〈p〉Author(s): Ahmed Said, Qiwu Zhang, Jun Qu, Yanchu Liu, Zhiwu Lei, Huimin Hu, Zhigao Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phlogopite, one trioctahedral mica, was activated by solvent-free ball milling to serve directly as slow-release potassium fertilizer. Before the final breakdown of the crystal structure, phase transformation of trigonal phlogopite into monoclinic by milling at 300 rpm for 120 min was observed for the first time. Different solubility of the amorphous product and monoclinic crystalline product in water or 2% citric acid was also obtained. The content of water soluble potassium (quick acting potassium) and 2.0% citric acid soluble one (slow release potassium) in the products could be easily changed by adjusting the milling speed depending on the requirement for plant growth. 100.0% K extraction in 2.0% citric acid solution from the amorphous sample and near 30% K extraction in water from the sample milled at 300 rpm was achieved. Several analytical methods such as XRD, SEM, FT-IR and TG-DTG were used to characterize the activated sample and to understand the reason for the easier dissolution of potassium. The proposed process was economical and environment-friendly, which could help to maintain a balanced supply of potassium fertilizer for sustainable development of agriculture by compensating partially current high-cost chemical fertilizer.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 174〈/p〉 〈p〉Author(s): Khaled Charradi, Zakarya Ahmed, Pilar Aranda, Radhouane Chtourou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Anionic and cationic clays were here evaluated as nanofillers of low sulfonated polyetheretherketone (SPEEK, DS = 56%) for preparation of nanocomposite electrolyte membranes for PEMFC (Proton Exchange Membrane Fuel Cells) applications. A synthetic Mg〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al layered double hydroxide (LDH) exchanged with sulfate anions and a porous SiO〈sub〉2〈/sub〉-montmorillonite heterostructured material containing delaminated clay particles, were added to SPEEK polymer for preparation of composite membranes with different nanofiller content (3, 6 and 9%). The resulting membranes were characterized concerning their structure, morphology and electrical conductivity performance. The incorporation of the Mg〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al LDH and the SiO〈sub〉2〈/sub〉-motmorillonite fillers into the SPEEK seems to enhance water retention and the thermal stability of the resulting composite electrolyte membranes. Moreover, the composite electrolyte membranes show higher proton conductivity than the neat SPEEK membrane (0.023 S cm〈sup〉−1〈/sup〉) after incorporation of the LDH and the SiO〈sub〉2〈/sub〉-motmorillonite fillers (0.070 and 0.158 S cm〈sup〉−1〈/sup〉 respectively) at 120 °C and 100% relative humidity, which can be relevant for increasing the performance at high temperature of this type of membranes in fuel cell applications.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S016913171930105X-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 174〈/p〉 〈p〉Author(s): Huiwen Chen, Zepeng Zhang, Guanzheng Zhuang, Rui Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the study, a new vacuum method was applied to prepare the hybrid pigments of sepiolite and Basic red 46 (XL-GRL). Various hybrid pigments respectively prepared by the vacuum method, solid method and liquid method were compared. The obtained products were respectively labeled as VM, SM and LM. The prepared pigments were then characterized and tested by X-ray diffraction, Fourier Transform infrared spectroscopy, scanning electron microscopy, and N〈sub〉2〈/sub〉 physisorption method. The effects of the preparation methods on the structure, morphology, composition, chemical stability and thermal stability of the hybrid pigments were explored. The results indicated that XL-GRL was mainly adsorbed on the sepiolite via electrostatic attraction after heating at 150 °C. In addition, more XL-GRL molecules could be encapsulated in sepiolite channels in VM and exhibited the more stable performance than those in SM and LM in the chemical, thermal and color stability tests. Therefore, the vacuum method could effectively improve the stability of the hybrid pigments.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 174〈/p〉 〈p〉Author(s): Javiera Cervini-Silva, Gerardo Ruiz, José Manuel Hernández, Sergio Hernández, Eduardo Palacios, Perla Morales Gil, Kristian Ufer, Ruth Jacquelin Rosa Cruz, Maripaz Orta, Stephan Kaufhold〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Methane (CH〈sub〉4〈/sub〉) is a clean source of energy, thus current large-scale efforts aim to produce this hydrocarbon. Little is known on how the surface reactivity of clays contributes to the 〈em〉in situ〈/em〉 production of CH〈sub〉4〈/sub〉. This paper reports on the natural production of CH〈sub〉4〈/sub〉 after reacting four nontronites, iron-rich dioctahedral smectites [Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 〈em〉ca.〈/em〉 30% and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 〈 12%], against bicarbonate under strict, free-oxygen conditions at 25 °C. The analytical techniques used included X-ray fluorescence, X-ray diffraction, elemental analysis, gas chromatography, high-resolution scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy, and nano-diffraction. The production of CH〈sub〉4〈/sub〉 reached 5700 ppbv. By way of comparison, registered concentrations for CH〈sub〉4〈/sub〉 in the aqueous nontronite dispersions surpassed the average concentration of CH〈sub〉4〈/sub〉 in the Earth's atmosphere (1.774 ppbv), and the planetary budget of CH〈sub〉4〈/sub〉 for the Mars surface (10–250 ppbv). Fitting functions for the production of CH〈sub〉4〈/sub〉 were calculated. The highest production of CH〈sub〉4〈/sub〉 was registered in dispersions containing nontronites with lower contents of Fe (%Fe). The cumulative production of CH〈sub〉4〈/sub〉 (ΣCH〈sub〉4〈/sub〉 after 60 d) varying with %Fe according to: 〈em〉y〈/em〉 = −171.5(〈em〉x〈/em〉) + 7348, 〈em〉r〈/em〉〈sup〉〈em〉2〈/em〉〈/sup〉 = 0.98 (〈em〉n〈/em〉 = 4). Increases in proton activity favored the production of CH〈sub〉4〈/sub〉, 〈em〉in lieu〈/em〉 with the notion that corrosion of highly-reduced, Fe nanodomains that occur naturally on nontronite surfaces render protons that hydrogenate carbon centres. Meanwhile, bicarbonate acted not as spectator anion, for which it acted as carbon source. On the other hand, microscopic observations identified the presence of biosignatures in nontronite, denoting asexual and sexual reproduction of bacterial iron-oxidizers, proper of a lithotrophic environment. In summary, both CH〈sub〉4〈/sub〉 production and carbon assimilation were best explained because the reduction of carbonate by labile, highly-reactive Fe nanodomains present in nontronite under environmental conditions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131719300973-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 June 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 174〈/p〉 〈p〉Author(s): Yunshan Xu, De'an Sun, Zhaotian Zeng, Haibo Lv〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal conductivity of compacted bentonite is one of the parameters affecting the behaviour of high-level radioactive waste (HLW) repositories, where the bentonite will be used as a buffer. Because the heat released from the HLW will be diffused across the buffer, understanding the thermal properties of buffer materials is necessary to accurately assess the thermal performance of the HLW repository. In this study, the thermal conductivity of compacted Gaomiaozi (GMZ07) and Wyoming (MX80) bentonites was measured and investigated under different testing conditions: temperature, water content and dry density. The obtained results showed that the thermal conductivity of compacted bentonites increased with increasing temperature. The thermal conductivity increased noticeably with temperature above 60 °C, while the change in thermal conductivity with temperature was small at temperature ranging from 5 to 60 °C. The temperature effect on thermal conductivity decreased with increasing dry density, and for a dry specimen, the thermal conductivity was negligibly changed with temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Yongfeng Deng, Tongwei Zhang, Yujun Cui, Yonggui Chen, Tingting Deng, Xiaorong Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The framework of the intrinsic compression behaviour of normally consolidated soft clay proposed by Burland (1990) is widely adopted in engineering practices. However, further investigations should be conducted on its validity in the coastal and offshore environments to verify the effect of pore water salinity. In the present work, oedometer tests were performed on remoulded artificial soft clays (mixtures of kaolin and bentonite with 0%, 5%, 10%, and 20% of bentonite by mass). The artificial clays were salinized with sodium chloride solutions at concentrations 0 mol/L (distilled water), 0.17 mol/L, 0.51 mol/L, 0.86 mol/L, and 1.70 mol/L at water contents equal to 1.0–1.5 times of the liquid limits. The results showed that the ‘intrinsic’ properties of clays, including the compression index 〈em〉C〈/em〉〈sub〉c〈/sub〉〈sup〉⁎〈/sup〉(100–1000 kPa), void ratio 〈em〉e〈/em〉〈sub〉100〈/sub〉*, and compression line based on the void index 〈em〉I〈/em〉〈sub〉v〈/sub〉, changed with the pore water salinity. Following the empirical correlation proposed by previous researchers, the decrease in 〈em〉C〈/em〉〈sub〉c〈/sub〉〈sup〉⁎〈/sup〉 caused by pore water salinity could be generally characterised by the liquid limit and void ratio at the liquid limit (〈em〉e〈/em〉〈sub〉L〈/sub〉). The dispersed correlation between the predicted 〈em〉e〈/em〉〈sub〉100〈/sub〉〈sup〉⁎〈/sup〉 and the experimental results in this study were caused by the significant changes in 〈em〉e〈/em〉〈sub〉0〈/sub〉/〈em〉e〈/em〉〈sub〉L〈/sub〉 controlled by pore water salinity. The relationships between void index 〈em〉I〈/em〉〈sub〉v〈/sub〉 and vertical stress 〈em〉σ〈/em〉〈sub〉v〈/sub〉’ deviated from the intrinsic compression line (〈em〉ICL〈/em〉) under the saline environment. For the artificial clay rich in smectite, the slopes of 〈em〉I〈/em〉〈sub〉v〈/sub〉–log 〈em〉σ〈/em〉〈sub〉v〈/sub〉’ before yielding increased with pore water salinity at the initial water content. Pore water salinity affected the intrinsic compression behaviour of soft clays primarily composed of kaolinite to a lesser extent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Shun Wang, Peixin Du, Peng Yuan, Xuemin Zhong, Yaqi Liu, Dong Liu, Liangliang Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work investigated changes in the chemical composition, structure and porosity of hollow spherical allophane under alkaline conditions, which are significant not only for understanding its fate in natural environment but also for its functional applications. Hollow spherical allophane with a silicon/aluminium (Si/Al) molar ratio of 0.77 was hydrothermally synthesised followed by treatment with dilute sodium hydroxide (NaOH) solutions with different concentrations (indicated by pH values). The allophane and its alkali-treated products were then characterized using a combination of techniques, such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance and nitrogen physisorption analysis. Allophane showed a weak structural stability in alkaline conditions. At pH ≤ 11.0, the framework of allophane particles was almost intact; its polymerised silicates showed only slight dissolution. At a higher pH (〉 11.0), desilication and dealumination enhanced, resulting in the destruction of the imogolite local structure (ImoLS) along the edges of defect pores and the formation of amorphous materials. Most of the defect pores increased in size, becoming accessible to nitrogen and the textural parameters of the micropores reached their maximum values at a pH of 12.5. However, the damage to some secondary pores and the collapse of some hollow spherules reduced total pore volume (〈em〉V〈/em〉〈sub〉total〈/sub〉). At a pH of 13.0, most of the hollow spherules were observed to have collapsed, resulting in remarkable decrease in the textural parameters. However, some unbroken and/or mildly broken allophane particles might remain, deduced from the relatively high BET specific surface area (SSA) and 〈em〉V〈/em〉〈sub〉total〈/sub〉 and the considerable proportion of micropores for Allo〈sub〉13.0〈/sub〉. These results reveal the dissolution behaviour of allophane in alkaline conditions and the mechanism underlying this behaviour, providing essential insights into the mineral's potential applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Applied Clay Science, Volume 166〈/p〉 〈p〉Author(s): Joanna Szymanska, Pawel Wisniewski, Paulina Wawulska-Marek, Jaroslaw Mizera〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Currently, the global oil & gas sector is focused on enhanced natural gas exploration from unconventional rock formations. The potential deposits are located within large-scale basins of impermeable shales (hydrocarbons accumulated in closed pores) with plastic zones at great depths with high reservoir pressure. These severe geological conditions determine the application of granulated propping agents, named “proppants”. They are pumped with hydraulic fluid during hydraulic fracturing and subsequently locate tightly inside created rock fractures. Proppants function as a prop to facilitate gas flow up the wellbore. Quartz sands are applied mainly for low pressure basins. However, only ceramic proppants, granules produced from raw clays in a mechanical granulation and sintering process, are proper for deeper shales due to their homogeneity, higher sphericity, and mechanical and chemical stability.〈/p〉 〈p〉Aim of this research was verification of the impact of natural loamy resources (aluminosilicates in powder form) mixed with binder on ceramic proppants quality. Utility of the clays was estimated by their particle size distribution (PSD by laser diffraction method) and thermal stability (thermogravimetry - TGA). The unique platy morphology was determined by scanning electron microscopy (SEM), while energy dispersive spectroscopy (EDS), X-ray fluorescence (XRF) and X-ray diffraction (XRD) revealed chemical-phase composition. Moreover, aluminosilicates were subjected to analysis of specific surface area (BET method) – very crucial for powder consolidation into granules in mechanical granulation.〈/p〉 〈p〉Quality of the granulated, and consequently sintered, bodies was evaluated by calculations of roundness and sphericity coefficient, specific gravity and bulk density, combined with microtomography (μCT) - a key investigation of porosity and proppant settlement in fracture. SEM studies also revealed phase transitions due to high temperature exposition of the green proppants and the correlation with proppant strength, evaluated in crush tests. Moreover, measurements of turbidity and solubility in acids revealed risk of the granules' decay in the shale gas wells.〈/p〉 〈p〉The obtained outcomes show dependence of the proppant's structure on the binder and the loamy materials ratio, proving the utility of the applied natural resources in the granules production. In consequence, these proppants can be used for hydraulic fracturing in severe mining conditions in accordance to the strict international ISO standards.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169131718304319-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉