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  • 1
    Publication Date: 2011-05-05
    Description: Hydroxy sodalite (HS) particles were synthesized hydrothermally at 90°C for 10 h in the presence of cetyltrimethylammonium bromide (CTAB) and other aqua-based precursor materials like sodium aluminate, sodium metasilicate, and water. Crystalline phases and microstructures of the synthesized particles were studied by X-ray diffraction and field emission scanning electron microscopy, respectively. The effect of CTAB concentrations on the crystallinity and morphology of the synthesized particles was investigated. Thread-ball like HS particles along with some cube-shaped zeolite A were obtained in the presence of 0–0.5 mM CTAB while flower-like HS particles were observed in the presence of 1–5 mM of CTAB concentrations. With increase in CTAB concentration, HS phase increased significantly, and phase pure HS particles resulted for 3 and 5 mM of CTAB concentrations. A mechanism for the formation of flower-like HS particles was also proposed.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
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  • 2
    Publication Date: 2013-12-08
    Description: Mesoporous alumina (MA)was synthesized by sol–gel based evaporation-induced self-assembly process using aluminum isopropoxide as alumina source in the presence of three different types of triblock copolymers (TBCs), F68, F127, and L64. The role of different TBCs as surfactants on thermal, crystallization, textural, and microstructural properties of the alumina powders was studied. To understand the effects of different copolymers, the adsorption efficiency of the samples for Congo red (CR) was studied. For all the surfactants, the XRD results showed the stability of γ- Al 2 O 3 phase up to 1000°C for 1 h dwell time. A maximum value (431.8 m 2 /g) of Brunauer–Emmet–Teller surface area was obtained for the 400°C-treated powder prepared from F68 surfactant. The transmission electron microscopy micrograph exhibited worm-like mesoporous structures of the 400°C-treated powders prepared from F68 and F127 surfactants . The adsorption performance for CR of the 400°C-treated powders for different surfactants was in the order of F68 〉 F127 〉 L64. A tentative mechanism was illustrated to understand the roles of different block copolymers on the properties of the prepared MA.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 3
    Publication Date: 2011-12-13
    Description: The ZSM-5 zeolite powders were prepared through in situ extraction (extraction and conversion in single step process) of silica from rice husk ash in the presence of other aqueous-based precursors (sodium aluminate and tetrapropyl ammonium hydroxide) following a simple hydrothermal condition at 130°C–170°C. The powders were characterized by X-ray diffraction (XRD), thermogravimetry analysis (TGA), differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy, N 2 physisorption measurements, and field emission scanning electron microscopy (FESEM). Crystallizations of ZSM-5 were noticed at 130°C/96 h, 150°C/24 h, and 170°C/12 h. The exothermic peak at 422°C in DTA curve indicated the removal of tetrapropyl ammonium ions (TPA + ) used as structure directing agent (SDA). The vibration bands at around 550 and 1221 cm −1 indicated the presence of double 5-ring in ZSM-5. The 150°C–170°C-treated samples exhibited higher BET surface area and pore volume compared to those of 130°C-treated powders. The FESEM images showed coffin-shaped morphology of the powders, and their sizes increased with increase in both reaction temperature and time.
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 4
    Publication Date: 2011-12-15
    Description: The ZSM -5 zeolite particles have been prepared using triethanol amine as structure-directing agent under static hydrothermal condition at 170°C for 7 days. The particles were characterized by X-ray diffraction (XRD), thermogravimetry analysis (TGA), differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy, N 2 physisorption measurements, and field emission scanning electron microscopy (FESEM). The crystalline ZSM -5 was found at 170°C/7 days as shown by XRD. The vibration bands at around 549 and 1226 cm −1 in the FTIR spectra indicated the presence of double 5-ring in ZSM -5. The exothermic peak at 395°C in DTA curve indicated the removal of structure-directing agent. The BET surface area of the particles was 100 m 2 /g. The FESEM images showed coffin-shaped and broom-like crystals of ZSM -5.
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 5
    Publication Date: 2016-04-09
    Description: Aluminum hydrous oxides and their derivatives were prepared by a facile solvothermal process in the presence of formamide, dimethyl formamide, and diethyl formamide as solvents at 150°C/24 h. The as-synthesized products were calcined at 500°C/1 h to obtain γ-Al 2 O 3 . The crystallization behavior and microstructure of the pre- and postcalcination products were studied by X-ray diffraction and transmission electron microscopy, respectively. The surface textural properties of the calcined samples were investigated by N 2 adsorption–desorption analysis. The formamide and its derivatives played a significant role in tuning textural properties of the calcined products. The diethyl formamide based sample exhibited enhanced Brunauer–Emmett–Teller surface area and pore volume of 517 m 2 g −1 and 2 cm 3 g −1 , respectively. Both the as-prepared and calcined samples showed variable morphologies and crystallinity using different solvents. The trend in morphological changes as nanosheet nanorod nanowire bundles occurred in the presence of formamide, dimethylformamide, and diethylformamide, respectively. A tentative mechanism has been illustrated for the formation of the products.
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    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 6
    Publication Date: 2013-05-04
    Description: Mesoporous γ- Al 2 O 3 powders with nanofiber and nanorod-like structures were synthesized using boehmite sols in the presence of triblock copolymer, P123 in ethanol by solvothermal process at different temparatures (100°C–165°C) followed by calcination at 400°C–1000°C. The powders were characterized by low- and wide-angle X-ray diffraction (XRD), N 2 adsorption–desorption, and transmission electron microscopy (TEM). The adsorption efficiency of the powders with Congo red (CR) was studied by UV–vis spectroscopy. The γ- Al 2 O 3 phase became stable up to 1000°C. The nanorods obtained at 165°C had narrower pore size distribution (PSD) than nanofibers synthesized at 100°C, the former showed higher CR adsorption efficiency. The stepwise growth mechanism of nanofibers to nanorods conversion with increase in solvothermal temperatures was illustrated.
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    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 7
    Publication Date: 2012-11-17
    Description: Zeolite Na A membranes were prepared hydrothermally by secondary crystallization process at different temperatures (55°C–75°C) on porous α-alumina-based support tubes (inner side) precoated with poly(ethyleneimine) (PEI) buffer layer and Na A seed particles. The Na A seed crystals synthesized at 65°C/2 h in the size range 100–200 nm having BET surface area of 71.57 m 2 g −1 were used for secondary crystallization of the membranes. The secondary crystallization at 65°C for (4 + 4) h (double-stage) showed highly dense Na A grains in the microstructure of the membrane with a thickness of 5 μm. It rendered the permeance values of 50.6 × 10 −8 , 2.47 × 10 −8 , and 0.55 × 10 −8  molm −2 s −1 Pa −1 for H 2 , N 2 , and CO 2 , respectively, with their permselectivity of 20.48 ( H 2 / N 2 ), 92 ( H 2 / CO 2 ), and 4.49 ( N 2 / CO 2 ). A tentative mechanism was illustrated for the interaction of PEI with the support substrate and Na A seed crystals.
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    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 8
    Publication Date: 2012-11-17
    Description: Nanofiber-like mesoporous γ- Al 2 O 3 was synthesized using freshly prepared boehmite sol in the presence of triblock copolymer, P123 following evaporation-induced self-assembly (EISA) process followed by calcinations at 400°C–1000°C. The samples were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), N 2 adsorption–desorption, and transmission electron microscopy (TEM). The adsorption efficiency of the samples with Congo red (CR) was studied by UV – vis spectroscopy. XRD results showed boehmite phase in the as-prepared sample while γ- Al 2 O 3 phase obtained at 400°C was stable up to 900°C, a little transformation of θ- Al 2 O 3 resulted at 1000°C. The Brunauer-Emmett-Teller surface area of the 400°C-treated sample was found to be 175.5 m 2 g − 1 . The TEM micrograph showed nanofiber-like morphology of γ- Al 2 O 3. The 400°C-treated sample showed about 100% CR adsorption within 60 min.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 9
    Publication Date: 2006-04-01
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley on behalf of American Ceramic Society.
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  • 10
    Publication Date: 2011-12-01
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley on behalf of American Ceramic Society.
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