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  • Articles  (825)
  • International Journal of Chemical Engineering  (393)
  • 109822
  • Process Engineering, Biotechnology, Nutrition Technology  (825)
  • 1
    Publication Date: 2020-08-25
    Description: The article addresses the extended Graetz–Nusselt problem in finite-length microchannels for prescribed wall heat flux boundary conditions, including the effects of rarefaction, streamwise conduction, and viscous dissipation. The analytical solution proposed, valid for low-intermediate Peclet values, takes into account the presence of the thermal development region. The influence of all transport parameters (Peclet Pe, Knudsen Kn, and Brinkman Br) and geometrical parameters (entry length and microchannel aspect ratio) is investigated. Performances of different wall heat flux functions have been analyzed in terms of the averaged Nusselt number. In the absence of viscous dissipation Br=0, the best heating protocol is a decreasing wall heat flux function. In the presence of dissipation Br〉0, the best heating protocol is a uniform wall heat flux.
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  • 2
    Publication Date: 2020-08-25
    Description: At present, there are two main standards, ISO 23828 : 2013 and SAE J 2572–2014, which prescribe the hydrogen consumption test using the pressure method, gravimetric method, and flow method. However, these methods do not meet the test requirements for electric energy consumption and the range of plug-in hybrid fuel cell vehicles (FCVs) which are the main technical considerations in China and Europe. In this paper, a new test method for the hydrogen consumption, electric energy consumption, and range of FCVs is proposed without the use of additional hydrogen supply, measurement instruments, or energy consumption correction, which can improve the operability of the test and avoid the conversion between electric energy and hydrogen. One plug-in hybrid FCV and one nonplug-in hybrid FCV were tested using the proposed method. The results show that the new method meets the requirements of fuel economy test for FCVs with hydrogen consumption rate, electric energy consumption rate, the range for plug-in hybrid FCVs, hydrogen consumption rate, and the range for nonplug-in FCVs.
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  • 3
    Publication Date: 2020-08-28
    Description: The unstoppable quest for low-cost reinforcing agent gingered the enthusiasm towards developing and utilising the agro-based waste product as reinforcement since they are promptly accessible, sustainable, and inexpensive to purchase. In this study, AA6061/rice husk ash matrix composites were produced through metallurgical stir casting techniques. Different weight percentages of reinforcement in the range of 2%, 4%, 6%, and 8% were used to fabricate the composites. The reinforced composites were characterized by SEM/EDS for microstructural study. The mechanical behaviour was examined for all the produced samples. SEM/EDS analysis revealed the presence of silica, a major constituent of rice husk ash in the produced composites. The results of the mechanical behaviour show that upgrading the weight percentage of reinforcing agent increases the mechanical properties. AA6061/8% rice hush ash generated a consistent rise with filler concentration in comparison with the aluminium alloy in all operating functions.
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  • 4
    Publication Date: 2015-09-16
    Description: This study describes the preparation, characterization, and evaluation of performance of blend Polyethersulfone (PES) with manganese(III) acetylacetonate Mn(acac)3 to produce reverse osmosis blend membrane. The manganese(III) acetylacetonate nanoparticles were prepared by a simple and environmentally benign route based on hydrolysis of KMnO4 followed by reaction with acetylacetone in rapid stirring rate. The prepared nanoparticle powder was dissolved in polymer solution mixture to produce RO PES/Mn(acac)3 blend membrane, without any treatment of Polyethersulfone membrane surface. The membrane morphology, mechanical properties, and performance were presented. The scanning electron microscopy (SEM) images have displayed a typical asymmetric membrane structure with a dense top layer due to the migration of Mn(acac)3 nanoparticles to membrane surface during the phase inversion process. Contact angle measurements have indicated that the hydrophilicity of the membrane was improved by adding Mn(acac)3. AFM images have proved excellent pores size distribution of blend membrane and lower surface roughness compared with bare PES. The desalination test was applied to blend membrane, where the blend membrane provided good performance; particularly, permeate flux was 24.2 Kg/m2·h and salt rejection was 99.5%.
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  • 5
    Publication Date: 2015-10-27
    Description: This work studied the influence of textural characteristics of CNTs on catalytic performance of Ni/CNTs for CO2 methanation. The CNTs supports were prepared by chemical vapor deposition method using Ni/MgO catalysts, and acetonitrile and ethanol were used as carbon sources, respectively. The Ni/CNTs catalysts were prepared via impregnation method and characterized by X-ray diffraction (XRD), N2 adsorption/desorption, and temperature-programmed reduction (H2-TPR) techniques. The results indicated that the textural characteristics of CNTs supports significantly impacted on the catalytic performance of Ni/CNTs. The catalyst Ni/CNTs-E (CNTs using ethanol as carbon source) had good reducibility, high specific surface area, and moderate defects, resulting in higher CO2 conversion and CH4 yield, followed by Ni/CNTs-C (commercial CNTs) and Ni/CNTs-A (CNTs using acetonitrile as carbon source). Based on Arrhenius formula, activation energies of the catalysts were calculated and were found decreased for Ni/CNTs-A and Ni/CNTs-E.
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  • 6
    Publication Date: 2015-05-26
    Description: A photodegradation process of methylene blue (MB) in aqueous solution using Fe(III)/TiO2-montmorillonite photocatalyst is presented. The photocatalyst material was prepared using Indonesian natural montmorillonite in TiO2 pillarization process followed by Fe(III) ion exchange. Kinetic study on MB degradation was conducted and evaluated by three kinetic models: the pseudo-first- and second-order equations and the Elovich equation. From the results, it is concluded that the degradation under the photo-Fenton-like process utilizing Fe(III)/TiO2-montmorillonite photocatalyst conformed to the Elovich kinetic model.
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  • 7
    Publication Date: 2016-06-24
    Description: This study focuses on performance analysis of a 1  microcogeneration system based on a high temperature proton exchange membrane (HT-PEM) fuel cell by means of parametric investigation. A mathematical model for a system consisting of a fuel processor (steam reforming reactor and water-gas shift reactor), a HT-PEM fuel cell stack, and the balance-of-plant components was developed. Firstly, the fuel processor performance at different fuel ratios and equivalence ratio was examined. It is shown that high fuel ratios of 0.9–0.95 and equivalence ratios of less than 0.56 are suitable for acceptable carbon monoxide content in the synthetic gas produced. Secondly, a parametric study of the system performance at different fuel and equivalence ratios using key system operating parameters was conducted. Steam-to-carbon ratio, stack operating temperature, and anode stoichiometry were varied to observe the changes in the microcogeneration system. The analysis shows that the system can reach electrical and cogeneration efficiencies of 30% and 84%, respectively.
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  • 8
    Publication Date: 2013-09-06
    Description: The preparation of carbon nanotube/metallic particle hybrids using pressed porous stainless steel pellets as a substrate is described. The catalytic growth of carbon nanotubes was carried out by CVD on a nickel catalyst obtained by impregnation of pellets with a highly dispersive colloidal solution of nickel acetate tetrahydrate in ethanol. Granular polyethylene was used as the carbon source. Metallic particles were deposited by thermal evaporation of Pt and Ag using pellets with grown carbon nanotubes as a base. The use of such composites as fuel cell electrodes is discussed.
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  • 9
    Publication Date: 2013-09-12
    Description: An experiment of hydrogen preparation from steam-carbon reaction catalyzed by K2CO3 was carried out at 700°C, which was driven by the solar reaction system simulated with Xenon lamp. It can be found that the rate of reaction with catalyst is 10 times more than that without catalyst. However, for the catalytic reaction, there is no obvious change for the rate of hydrogen generation with catalyst content range from 10% to 20%. Besides, the conversion efficiency of solar energy to chemical energy is more than 13.1% over that by photovoltaic-electrolysis route. An analysis to the mechanism of catalytic steam-carbon reaction with K2CO3 is given, and an explanation to the nonbalanced [H2]/[CO + 2CO2] is presented, which is a phenomenon usually observed in experiment.
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  • 10
    Publication Date: 2013-09-13
    Description: An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 μm of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process.
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  • 11
    Publication Date: 2013-09-24
    Description: This paper considers both LCA and LCC of the pyrolysis of switchgrass to use as an energy source in a conventional power plant. The process consists of cultivation, harvesting, transportation, storage, pyrolysis, transportation, and power generation. Here pyrolysis oil is converted to electric power through cocombustion in conventional fossil fuel power plants. Several scenarios are conducted to determine the effect of selected design variables on the production of pyrolysis oil and type of conventional power plants. The set of design variables consist of land fraction, land shape, the distance needed to transport switchgrass to the pyrolysis plant, the distance needed to transport pyrolysis oil to electric generation plant, and the pyrolysis plant capacity. Using an average agriculture land fraction of the United States at 0.4, the estimated cost of electricity from pyrolysis of 5000 tons of switchgrass is the lowest at $0.12 per kwh. Using natural gas turbine power plant for electricity generation, the price of electricity can go as low as 7.70 cent/kwh. The main advantage in using a pyrolysis plant is the negative GHG emission from the process which can define that the process is environmentally friendly.
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  • 12
    Publication Date: 2013-09-25
    Description: As the global atmospheric emissions of carbon dioxide (CO2) and other greenhouse gases continue to grow to record-setting levels, so do the demands for an efficient and inexpensive carbon sequestration system. Concurrently, the first-world dependence on crude oil and natural gas provokes concerns for long-term availability and emphasizes the need for alternative fuel sources. At the forefront of both of these research areas are a family of enzymes known as the carbonic anhydrases (CAs), which reversibly catalyze the hydration of CO2 into bicarbonate. CAs are among the fastest enzymes known, which have a maximum catalytic efficiency approaching the diffusion limit of 108 M−1s−1. As such, CAs are being utilized in various industrial and research settings to help lower CO2 atmospheric emissions and promote biofuel production. This review will highlight some of the recent accomplishments in these areas along with a discussion on their current limitations.
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  • 13
    Publication Date: 2013-09-29
    Description: An analysis is performed to study the heat and mass transfer on the flow past an infinite moving vertical cylinder, in the presence of first-order chemical reaction. The closed-form solutions of the dimensionless governing partial differential equations are obtained in terms of Bessel's functions and modified Bessel's functions by the Laplace transform technique. The transient velocity profiles, temperature profiles, and concentration profiles are studied for various sets of physical parameters, namely, the chemical reaction parameter, Prandtl number, Schmidt number, thermal Grashof number, mass Grashof number, and time. The skin friction, Nusselt number, and Sherwood number are also obtained and presented in graphs. It is observed that in presence of as well as increase in chemical reaction the flow velocity decreases. Also, in presence of destructive chemical reaction the concentration profile and Sherwood number tend to the steady state at large time.
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  • 14
    Publication Date: 2013-10-01
    Description: Perovskite structure oxygen carriers with the general formula CaMnxMg1-xO3-δ were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900°C to 1050°C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH4 to CO2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO3-δ. The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO3-δ have no thermodynamic limitations for methane oxidation to CO2 and H2O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work.
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  • 15
    Publication Date: 2013-06-13
    Description: An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was followed by a liquid-liquid extraction stage using acetonitrile as a polar solvent to remove produced sulfones from the model fuel. The impact of operating parameters including the molar ratio of formic acid to sulfur (), hydrogen peroxide to sulfur (), and the time of reaction was investigated using Box-Behnken experimental design for oxidation of the model fuel. A significant quadratic model was introduced for the sulfur removal as a function of effective parameters by the statistic analysis.
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  • 16
    Publication Date: 2015-05-01
    Description: A thermogravimetric analyzer was employed to investigate the thermal behavior and extract the kinetic parameters of Canadian lignite coal. The pyrolysis experiments were conducted in temperatures ranging from 298 K to 1173 K under inert atmosphere utilizing six different heating rates of 1, 6, 9, 12, 15, and 18 K min−1, respectively. There are different techniques for analyzing the kinetics of solid-state reactions that can generally be classified into two categories: model-fitting and model-free methods. Historically, model-fitting methods are broadly used in solid-state kinetics and show an excellent fit to the experimental data but produce uncertain kinetic parameters especially for nonisothermal conditions. In this work, different model-free techniques such as the Kissinger method and the isoconversional methods of Ozawa, Kissinger-Akahira-Sunose, and Friedman are employed and compared in order to analyze nonisothermal kinetic data and investigate thermal behavior of a lignite coal. Experimental results showed that the activation energy values obtained by the isoconversional methods were in good agreement, but Friedman method was considered to be the best among the model-free methods to evaluate kinetic parameters for solid-state reactions. These results can provide useful information to predict kinetic model of coal pyrolysis and optimization of the process conditions.
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  • 17
    Publication Date: 2016-03-08
    Description: Fe modified rice husk was prepared as a low cost biosorbent for the removal of Cr(VI) and phenol both singly and in combination from single and binary simulated synthetic waste water. Rice husk was modified by treating with FeSO4·7H2O. The results showed that impregnation of iron onto the surface of rice husk improved the adsorption capability of both Cr(VI) and phenol. The effects of process parameters for multicomponent system such as pH, adsorbent dose, and contact time onto the percentage removal of both Cr(VI) and phenol were investigated. The experimental data for the adsorption of both Cr(VI) and phenol onto the surface of Fe modified rice husk applied to various kinetic and adsorption isotherm models. Multicomponent isotherm models such as Nonmodified Langmuir, Modified Langmuir, Extended Langmuir, Extended Freundlich, Competitive Nonmodified Redlich Peterson, Competitive Modified Redlich Peterson were applied. The results show that Extended Freundlich model best described the experimental data for both Cr(VI) and phenol from binary solution. Pseudo second-order model agreed well with Cr(VI) while pseudo first-order model agreed well with phenol. Maximum adsorption capacity in synthetic binary solution of Cr(VI) and phenol was found to be 36.3817 mg g−1 for Cr(VI) and 6.569 mg g−1 for phenol, respectively.
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  • 18
    Publication Date: 2016-03-09
    Description: This paper was focused on the investigation of a forward osmosis- (FO-) reverse osmosis (RO) hybrid process to cotreat seawater and impaired water from steel industry. By using this hybrid process, seawater can be diluted before desalination, hence reducing the energy cost of desalination, and simultaneously contaminants present in the impaired water are prevented from migrating into the product water through the FO and RO membranes. The main objective of this work was to investigate on pilot-scale system the performance of the combined FO pretreatment and RO desalination hybrid system and specifically its effects on membrane fouling and overall solute rejection. Firstly, optimization of the pilot-scale FO process to obtain the most suitable and stable operating conditions for practical application was investigated. Secondly, pilot-scale RO process performance as a posttreatment to FO process was evaluated in terms of water flux and rejection. The results indicated that the salinity of seawater reduced from 35000 to 13000 mg/L after 3 hrs using FO system, while after 6 hrs it approached 10000 mg/L. Finally, FO/RO system was tested on continuous operation for 15 hrs and it was demonstrated that no pollutant was detected neither in draw solution nor in RO permeate after the end of operating time.
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  • 19
    Publication Date: 2016-02-09
    Description: Stirred aerated tanks by double impellers are used in fermentation and various biological processes for water treatment, food industry, and pharmaceutical production. In this study, a generalized correlation model was developed for the dependent parameter (). The oxygen mass transfer from air to liquid takes place by rotating the double impellers (IBRC and PBPU) in the aerated tank. This model considers Reynolds number, Froude number, power number, the liquid height, and the spacing between impellers as the most significant specifications that are related to aerated tank performance. The spacing between the impellers is considered to be a design factor of such industrial equipment due to its remarkable impact on the oxygen mass transfer.
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  • 20
    Publication Date: 2019
    Description: Nowadays water bodies across the world are heavily polluted due to uncontrollable contamination of heavy metal particles, toxic dyes, and other harmful wastes discharged by emerging industries other than normal domestic wastages. This contamination needs sufficient control to protect the natural water bodies. There are various methodologies to be followed to perform wastewater treatment, in which the adsorption method of filtration is found to be efficient. The adsorption method is a high priority and preferable filtration method compared to other waste water treatment methods due to its peculiar characteristics. Considering the adsorption method, there are multiple options available in selecting material and methodology for the filtration process. In selecting the filtering material, there is much attraction towards graphene and its oxides, which have widespread range of differential applications in commercial industries because of their eco-friendly characteristic features. The importance of various graphene composites and their chemical properties is found to be significant in various fields. Analyzing the adsorbing properties of graphene widely, this article deeply reviews about the improvements and the technologies identified for using graphene and (GO) graphene oxide in wastewater treatment taken into discussion elaborately. Therefore, in this hard review, the advantages and demerits of using graphene for wastewater treatment as well as improving its properties to make it more suitable for wastewater treatment are detailed.
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  • 21
    Publication Date: 2019
    Description: A three-dimensional computational fluid dynamics (CFD) study was carried out for drilling fluid flow with drill cuttings in open channels. The flow is similar to the return flow when drilling, stream containing drilling fluid, and drill cuttings. The computational model is under the framework of the Eulerian multifluid volume of the fluid model. The Herschel–Bulkley rheological model was used to describe the non-Newtonian rheology of the drilling fluid, and the computational model was validated with experimental results for two-phase flow in the literature. The effect of flow depth and flow velocity in an open channel was studied for drill cutting size of up to 5 mm and for a solid volume fraction of up to 10%. For constant cross section and short open channels, the effect of drill cuttings on flow depth and mean velocity was found to be small for particle sizes less than 5 mm and solid volume fractions less than 10%. High momentum force in the downward direction can carry the solid-liquid mixture at higher velocities than a lower density mixture. Higher inclination angles mean that the gravity effect upon the flow direction is more significant than the particle friction for short channels.
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  • 22
    Publication Date: 2018
    Description: The air-flow impacting based mechanochemical synthesis is an alternative strategy to traditional mechanochemical preparations, which has many advantages in terms of reaction temperature, preparation speed, and cleanness. Herein, we theoretically study the effect of instrument parameters, including the axial position of physical target, the diameter difference between nozzle throat and suction pipe, and divergence angles of uniform speed region, on the flow field of the air-flow impacting based mechanochemical synthesis. The optimized parameters have been obtained. Under the optimal conditions, a stable and high-speed air flow is obtained, in which the speed can achieve a Mach number of approximately 2.6. The high-speed air flow is able to easily carry the reacting substances to arrive at the physical target, triggering a chemical reaction. These findings undoubtedly provide a key guideline for further development and application of the air-flow impacting based mechanochemical synthesis.
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  • 23
    Publication Date: 2018
    Description: This paper reviews the use of domestic microwave ovens as plasma reactors for applications ranging from surface cleaning to pyrolysis and chemical synthesis. This review traces the developments from initial reports in the 1980s to today’s converted ovens that are used in proof-of-principle manufacture of carbon nanostructures and batch cleaning of ion implant ceramics. Information sources include the US and Korean patent office, peer-reviewed papers, and web references. It is shown that the microwave oven plasma can induce rapid heterogeneous reaction (solid to gas and liquid to gas/solid) plus the much slower plasma-induced solid state reaction (metal oxide to metal nitride). A particular focus of this review is the passive and active nature of wire aerial electrodes, igniters, and thermal/chemical plasma catalyst in the generation of atmospheric plasma. In addition to the development of the microwave oven plasma, a further aspect evaluated is the development of methodologies for calibrating the plasma reactors with respect to microwave leakage, calorimetry, surface temperature, DUV-UV content, and plasma ion densities.
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  • 24
    Publication Date: 2018
    Description: The properties of 3 binary mixtures containing piperazine were investigated in this work. In a first step, the densities for the two binary mixtures (piperazine + methanol) and (piperazine + acetone) were measured in the temperature range of 293.15 to 328.15 K and 293.15 to 323.15 K, respectively, at atmospheric pressure by using a Rudolph research analytical density meter (DDM 2911). The concentration of piperazine in the (piperazine + methanol) mixture was varied from 0.6978 to 14.007 mol/kg, and the concentration of piperazine in the (piperazine + acetone) mixture was varied from 0.3478 to 1.8834 mol/kg. On the other hand, the density data for the (piperazine + water) mixture were taken from the literature in the temperature range of 298.15 to 328.15 K. In a second step, for the 3 investigated systems, the apparent molar volume () and the limiting apparent molar volume () at infinite dilution were calculated using the Redlich–Mayer equation. The limiting apparent molar volumes () were used to study the influence of the solute-solvent and solute-solute interactions. The temperature dependency of the apparent molar volumes was used to estimate the apparent molar expansibility, Hepler’s constant , and isobaric thermal expansion coefficients .
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  • 25
    Publication Date: 2018
    Description: Biogas is a renewable fuel source of methane (CH4), and its utilization as a natural gas substitute or transport fuel has received much interest. However, apart from CH4, biogas also contains carbon dioxide (CO2) which is noncombustible, thus reducing the biogas heating value. Therefore, upgrading biogas by removing CO2 is needed for most biogas applications. In this study, an amine-functionalized adsorbent for CO2 capture from biogas was developed. Mesoporous MgO was synthesized and functionalized with different tetraethylenepentamine (TEPA) loadings by wet impregnation technique. The prepared adsorbents (MgO-TEPA) were characterized by X-ray diffraction (XRD) and N2 adsorption-desorption. The CO2 adsorption performance of the prepared MgO-TEPA was tested using simulated biogas as feed gas stream. The results show that the CO2 adsorption capacities of the adsorbents increase with increasing TEPA loading. The optimum TEPA loading is 40 wt.%, which gives the highest CO2 adsorption capacity of 4.98 mmol/g. A further increase in TEPA loading to 50 wt.% significantly reduces the CO2 adsorption capacity. Furthermore, the stability and regenerability of the adsorbent with 40% TEPA loading (MgO-TEPA-40) were studied by performing ten adsorption-desorption cycles under simulated biogas and real biogas conditions. After ten adsorption-desorption cycles, MgO-TEPA-40 shows slight decreases of only 5.42 and 5.75% of CO2 adsorption capacity for the simulated biogas and biogas, respectively. The results demonstrate that MgO-TEPA-40 possesses good stability and regenerability which are important for the potential application of this amine-based adsorbent.
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  • 26
    Publication Date: 2019
    Description: One of the main sources of activated carbon is biomass which can be transformed into char by pyrolysis. Apart from the obtaining coal, the pyrolysis of biomass can be used for the preparation of fuels, and this is why it is very important to determine its kinetic parameters for modelling. In the present research, the pyrolysis enthalpy of palm nut shells (Elaeis guineensis) was determined with the use of a differential scanning calorimetry study (DSC). To determine the kinetic parameters, the Not Reacted Core model was employed. This model considers that there is a heat and mass gradient between the furnace atmosphere and the interface formed during pyrolysis. To obtain the required data for the model, palm nut shells were submitted to pyrolysis in a Nichols furnace under reducing atmosphere. Samples were taken every 10 minutes to calculate char conversion. The experimental pyrolysis enthalpy resulted to be 301.81 J/g and then the monomeric units of cellulose, hemicellulose, and lignin were employed in order to determine the pyrolysis enthalpy per mole. The three biopolymers react with different mechanisms at different temperatures. The molecular weight resulted to be 172.38 g/mole, and the enthalpy for pyrolysis was 52.03 kJ/mol. For the application of the Not Reacted Core model, the amorphous char heat transfer coefficient was selected, and the value is 1.6 J/s·m·K. The reaction rate constant was 6.64 × 10−9 1/s assuming a first-order reaction, whereas the effective diffusion across the char layer was 4.83 × 10−7 m2/s.
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  • 27
    Publication Date: 2019
    Description: The qualitative and quantitative determination of the components of textile fibers takes an important position in quality control. A fast and nondestructive method of simultaneously analyzing four fiber components in blended fabrics was studied by near-infrared (NIR) spectroscopy combined with multivariate calibration. Two sample sets including 39 and 25 samples were designed by simplex mixture lattice design methods and used for experiment. Four components include wool, polyester, polyacrylonitrile, and nylon and their mixture is one of the most popular formulas of textiles. Uninformative variable elimination-partial least squares (UVEPLS) and the full-spectrum partial least squares (PLS) were used as the tool. On the test set, the mean standard error of prediction (SEP) and the mean ratio of the standard deviation of the response variable and SEP (RPD) of the full-spectrum PLS model and UVEPLS model were 0.38, 0.32 and 7.6, 8.3, respectively. This result reveals that the UVEPLS can construct local models with acceptable and better performance than the full-spectrum PLS. It indicates that this method is valuable for nondestructive analysis in the field of wool content detection since it can avoid time-consuming, costly, and laborious wet chemical analysis.
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  • 28
    Publication Date: 2018
    Description: 5-Ethoxymethylfurfural (EMF), one of the significant platform molecular derivatives, is regarded as a promising biofuel and additive for diesel, owing to its high energy density (8.7 kWh·L−1). Several catalytic materials have been developed for the synthesis of EMF derived from different feedstocks under relatively mild reaction conditions. Although a great quantity of research has been conducted over the past decades, the unsatisfactory production selectivity mostly limited to the range 50%–70%, and the classic fructose used as the substrate restricted its application for fuel manufacture in large scale. To address these production improvements, this review pays attention to evaluate the activity of various catalysts (e.g., mineral salts, zeolites, heteropolyacid-based hybrids, sulfonic acid-functionalized materials, and ionic liquids), providing potential research directions for the design of novel catalysts for the achievement of further improved EMF yields.
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  • 29
    Publication Date: 2018
    Description: In this work, the osmotic dehydration (OD) of Tunisian pomegranate seeds of “El Gabsi” variety was investigated. To optimize the process operating conditions, the effect of temperature, hypertonic solution solid content, and stirring speed was studied. The best conditions resulting in the higher water loss and the minimum of fruit damages found are 40°C, 50°Bx, and 440 rpm. In these conditions, the effect of blanching pretreatments on the solute and water transfer kinetics during the OD was investigated. The blanching pretreatments were carried out using two methods: blanching in a boiling water bath and in a microwave oven. The mass diffusion kinetic depends on time, temperature, hypertonic solution solid content, stirring speeds, and pretreatment process. Peleg’s model showed a good fit to the experimental data. By applying blanching pretreatments, the water and solute effective diffusivities passed from the order of 10−9 to the order of 10−8, and the OD equilibrium time was significantly reduced.
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  • 30
    Publication Date: 2019
    Description: In this study, a nonisothermal kinetics analysis of petcoke was performed at heating rates of 10, 15, and 20°C/min using thermal gravimetric analysis (TGA). The behaviour of petcoke at different gasification stages (dewatering, volatilization, char burning, and burnout) was studied. The effect of heating rate on the activation energy of petcoke gasification was also investigated. The activation energy of petcoke was estimated using different kinetic models that include volume reaction model (VRM), shrinking core model (SCM), random pore model (RPM), Coats and Redfern model (CRM), and normal distribution function (NDF). The NDF model was modified in this study. It was found that the experimental data were best fitted with the modified normal distribution function (MNDF) and SCM. The results also showed that activation energy decreases as heating rate increases, leading to reduction in gasification completion time.
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  • 31
    Publication Date: 2019
    Description: Nowadays, biomass has been employed to prepare biosorbents for heavy metals uptake; however, further disposal of polluted material has limited its application. In this work, nickel and lead removal was performed using yam peels and the resulting polluted biomass was mixed with concrete to produce bricks. The biomass was characterized by FT-IR analysis for testing functional groups diversification before and after adsorption process. The effect of adsorbent dosage, temperature, and initial solution concentration was evaluated to select suitable values of these parameters. Adsorption results were adjusted to kinetic and isotherm models to determine adsorption mechanism. Desorption experiments were also performed to determine the appropriate desorbing agent as well as its concentration. Immobilization technique of cement-based solidification/stabilization was applied and the polluted biomass was incorporated to concrete bricks at 5 and 10%. Mechanical resistance and leaching tests were carried out to analyze the suitability of heavy metals immobilization. The suitable values for dosage, temperature, and initial solution concentration were 0.5 g/L, 40°C and 100 ppm, respectively. The kinetic model that best fitted experimental results was pseudo-second order indicating a dominant physicochemical interaction between the two phases. The highest desorption yields were found in 52.47 and 74.84% for nickel and lead ions. The concrete bricks exhibited compression resistance above 5 MPa and all the leachate reported concentrations below the environmental limit. These results suggested that nickel and lead immobilization using concrete bricks is a good alternative to meet disposal problems of contaminated biomass.
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  • 32
    Publication Date: 2019
    Description: In this paper, the results of the study on the influence of the addition of 10 wt.% of FeCl3, CoCl2, NiCl2, ZnCl2, SnCl2, and CuCl2 on the wheat straw pyrolysis process are presented. The studied chlorides were found to affect the pyrolysis process; however, the highest activity was observed while using CuCl2. The presence of the copper chloride led to the decrease in the temperature of the initial destruction of hemicellulose fraction of wheat straw by 64°С. Besides, the use of CuCl2 allowed increasing the yield of liquid and solid pyrolysis products as well as decreasing the molecular weight distribution of the volatiles. Moreover, the increase in the hydrogen and decrease in carbon dioxide concentration were also observed in the presence of copper chloride. The analysis of the solid residue obtained in the wheat straw pyrolysis in the presence of CuCl2 showed the increase in the specific surface area of the carbon residue from 24 up to 63.5 m2/g in comparison with that obtained for the noncatalytic process.
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  • 33
    Publication Date: 2019
    Description: The process simulation performed in the present study aimed at investigating energetically self-sufficient wastewater treatment plant of 500,000 population equivalents. To implement this, three different scenarios were evaluated using computational tools named GPS-X® and SuperPro®. They were designed based on municipal wastes recovery to energy generation and its utilisation within the facility. An anaerobic/anoxic/oxic process for biological treatment of wastewater was considered and mesophilic anaerobic digestion at different scenarios (1) primary sludge (PS) with waste activated sludge (WAS), (2) PS with thermally hydrolysed WAS, and (3) PS with WAS and organic fractions derived from municipal solid waste. The results from scenario 1 and scenario 2 showed only enough thermal energy to meet their demand (they reach only 44 and 52% of electrical self-sufficiency, respectively), while positive net thermal and electrical energy result in scenario 3 from codigestion of sewage sludge and the organic fraction of municipal solid waste. The main limitation of tools used is their lack of sensitivity to economies of scale and their dependence on real data used for process design to obtain more accurate results.
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  • 34
    Publication Date: 2019
    Description: Biodiesel is the best candidate for fuel oil replacement, and to obtain it, heterogeneous catalysts offer large advantages: they can be separated from the product and reused. This work reviews a novel one-step synthesis of CaO-ZnO catalytic particles suitable for biodiesel production. The catalyst is synthesized using an original simple method that involves mixing of ZnO with CaCO3 and subsequent calcination. The CaO-ZnO microparticles obtained present an average size of 2 μm. This material shows the characteristic crystallographic cubic structure of CaO and the hexagonal phase of ZnO. The temperature-programmed reduction experiment evidences an interaction between CaO and ZnO. Moreover, the infrared spectroscopy shows typical bands of these compounds. The catalyst shows high biodiesel yield, up to 73% in the first cycle and 64% in the second one. In this work, the synthesis of an efficient CaO-ZnO catalyst with a huge potential is revealed, which could be an economic alternative to produce biodiesel.
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  • 35
    Publication Date: 2019
    Description: Chrysoidine is a type of industrial azo dye and a well-known toxicant. Due to its good dyeing characteristics, it is widely used for dyeing leather, paper, feather, grass, wood, bamboo, etc. Hence, it is very important to remove or reduce its concentration below the contamination level in the waste line by using low-cost technologies. Sawdust is a plentiful material available very cheaply from sawmills and woodworks. Therefore, the present work was conducted to study sorption ability of both raw sawdust and chemically activated sawdust carbon on the removal of chrysoidine from the aqueous solutions. Adsorption isotherms of the dye on sawdust were determined and correlated with usual isotherm equations like Freundlich and Langmuir. Experimental results have shown that sawdust has a high adsorption efficiency, and the adsorption of chrysoidine followed Freundlich’s isotherm. Although raw sawdust proved to be slightly less efficient in comparison to chemically treated sawdust but in economic terms, raw sawdust is more cost-effective as the difference in the percent dye removal is less than the difference in the manufacturing costs. The influence of several parameters such as effect of temperature, adsorbent dose, adsorption time, etc., on the adsorption process was studied along with thermodynamic parameters such as enthalpy (ΔH°) and entropy (ΔS°).
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  • 36
    Publication Date: 2019
    Description: The wastewater from industrial laundries has a high quantity of contaminants from the washing process, as well as chemical additives. Aiming at the treatment of this type of wastewater, the present study evaluated the performance of a combined coagulation/flocculation/sedimentation process (C/F/S) and membrane separation to treat laundry wastewater in relation to physicochemical parameters of water quality. For this purpose, a Doehlert experimental design was applied to the C/F/S step using the natural coagulant Tanfloc POP® with maximum color and turbidity removal efficiency obtained of 80.27% and 86.50%, respectively, under conditions of pH of 6.4 and a coagulant concentration of 110 mg·L−1. The supernatant from the C/F/S step was used in the sequential microfiltration (MF) and ultrafiltration (UF) experiments. The maximum values of color, total nitrogen, dissolved solids, and turbidity removal were similar to MF and UF membranes at transmembrane pressure of 1.4 bar, with the greatest flow of permeates (92.2 L·h−1·m−2) presented by the MF membrane at 1.4 bar. The total efficiency of the combined C/F/S-MF process indicated the quality of the treated wastewater since it reduced 98.4% of the color, 99.1% of turbidity, 71.7% of the surfactants, and more than 55% of the total dissolved solids (TDS), chemical oxygen demand (COD), and total organic carbon (TOC) from the industrial laundry wastewater. This study showed that the C/F/S-MF combined process could be an efficient treatment of laundry wastewater.
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  • 37
    Publication Date: 2019
    Description: Differences in morphology, pH, and electric charge of chitosan (CS) based hydrogels prepared by complexation with carboxymethylcellulose (CMC), carboxymethylated starch (CMS), and alginic acid (AA) at different polymers ratios and changing the order of addition were studied. CMC/CS and AA/CS hydrogels were amorphous and porous three-dimensional networks, with smaller pores at higher anionic polymer/CS ratios. Gelation time increased the agglomeration in the case of CMC/CS and CMS/CS gels. CMC/CS gels showed negative zeta potential values around −372 mV to −51 mV and CMS/CS gels in the range of −526 mV and −158 mV.
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  • 38
    Publication Date: 2015-09-30
    Description: The manganese complex of methionine hydroxy analogue was synthesized with methionine hydroxy analogue and manganese chloride as main raw materials. The composition and structure of the complex were characterized by elemental analyses, infrared spectra, and X-ray powder diffraction. The formula of the complex was Mn(C5H9O3S)2. The experimental results indicated that the manganese ion was, respectively, coordinated by the carboxylic and hydroxyl oxygen atoms from the methionine hydroxy analogue ligand. The crystal structure of the complex belonged to monoclinic system with the lattice parameters of = 1.2775 nm, = 1.5764 nm, = 1.5764 nm, and = 94.06°. The thermal decomposition process of the complex was studied by thermogravimetry and differential thermal analysis. The decomposition of the complex has taken place above 200°C. The residue was mainly manganese sulfide, and the experimental and calculated percentage mass loss was also given. The parameters of thermal decomposition kinetics for the complex, such as activation energy, reaction order, and preexponential factor, were calculated by using Kissinger, Flynn-Wall-Ozawa, and Freeman-Carroll methods, and the kinetic equations of the thermal decomposition were obtained.
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  • 39
    Publication Date: 2016-06-06
    Description: Equilibrium and dynamic adsorption of heavy metals onto spent coffee ground (SCG) were studied. The equilibrium adsorption of Cd2+, Cu2+, and Pb2+ in a batch system was modeled by an ion-exchange model (IEM) based on an ion-exchange of heavy metals with calcium and protons bonded to active sites on SCG surface. The maximum amount of adsorbed metal ions obtained using the IEM was 0.12, 0.21, and 0.32 mmol/g of Cd2+, Cu2+, and Pb2+, respectively. Regeneration of SCG was evaluated using citric acid, calcium chloride, and nitric acid. The observed trend of desorption efficiency through four adsorption-desorption cycles was HNO3 〉 CaCl2 〉 C6H8O7. The effect of process variables such as flow rate and bed height during the dynamic adsorption was evaluated. Moreover, the applicability of a mass transfer model based on external mass transfer resistance, axial dispersion, and ion-exchange isotherm was evaluated, and the results were in good agreement with the experimental data for the adsorption in SCG packed column. The sensitivity analysis of the model parameters showed that axial dispersion coefficient is the most significant parameter in the dynamic simulation. The results obtained showed the potential of SCG as a low-cost material for wastewater metal removal in continuous systems.
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  • 40
    Publication Date: 2016-06-10
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  • 41
    Publication Date: 2016-05-13
    Description: This paper investigates the performance of a ground source heat pump that is coupled with a photovoltaic system to provide cooling and heating demands of a zero-energy residential building. Exergy and sustainability analyses have been conducted to evaluate the exergy destruction rate and SI of different compartments of the hybrid system. The effects of monthly thermal load variations on the performance of the hybrid system are investigated. The hybrid system consists of a vertical ground source heat exchanger, rooftop photovoltaic panels, and a heat pump cycle. Exergetic efficiency of the solar-geothermal heat pump system does not exceed 10 percent, and most exergy destruction takes place in photovoltaic panel, condenser, and evaporator. Although SI of PV system remains constant during a year, SI of GSHP varies depending on cooling and heating mode. The results also show that utilization of this hybrid system can reduce CO2 emissions by almost 70 tons per year.
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  • 42
    Publication Date: 2015-01-19
    Description: The most expensive component of a fuel cell is the membrane electrode assembly (MEA), which consists of an ionomer membrane coated with catalyst material. Best-performing MEAs are currently fabricated by depositing and drying liquid catalyst ink on the membrane; however, this process is limited to individual preparation by hand due to the membrane’s rapid water absorption that leads to shape deformation and coating defects. A continuous coating line can reduce the cost and time needed to fabricate the MEA, incentivizing the commercialization and widespread adoption of fuel cells. A pilot-scale membrane coating line was designed for such a task and is described in this paper. Accurate process control is necessary to prevent manufacturing defects from occurring in the coating line. A linear-quadratic-Gaussian (LQG) controller was developed based on a physics-based model of the coating process to optimally control the temperature and humidity of the drying zones. The process controller was implemented in the pilot-scale coating line proving effective in preventing defects.
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  • 43
    Publication Date: 2012-12-26
    Description: Fluid catalytic cracking (FCC) riser reactors have complex hydrodynamics, which depend not only on operating conditions, feedstock quality, and catalyst particles characteristics, but also on the geometric configurations of the reactor. This paper presents a numerical study of the influence of different riser outlet designs on the dynamic of the flow and reactor efficiency. A three-dimensional, three-phase flow model and a four-lump kinetic scheme were used to predict the performance of the reactor. The phenomenon of vaporization of the liquid oil droplets was also analyzed. Results showed that small changes in the outlet configuration had a significant effect on the flow patterns and consequently, on the reaction yields.
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  • 44
    Publication Date: 2013-03-07
    Description: The impact of mixing on the promotion of microorganism growth rate has been analyzed using a multiphase forced-circulation pipe-loop reactor model capable of identifying conditions under which it is possible to convert natural gas into Single-Cell Protein. The impact of mixing in the interphase mass transfer was found to exert a critical role in determining the overall productivity of the bioreactor, particularly at the high cell loadings needed to reduce the capital costs associated with the large-scale production needed for the production of relatively low-value SCP in a sustainable manner.
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  • 45
    Publication Date: 2013-03-07
    Description: Annular centrifugal extractors (ACE), also called annular centrifugal contactors offer several advantages over the other conventional process equipment such as low hold-up, high process throughput, low residence time, low solvent inventory and high turn down ratio. The equipment provides a very high value of mass transfer coefficient and interfacial area in the annular zone because of the high level of power consumption per unit volume and separation inside the rotor due to the high g of centrifugal field. For the development of rational and reliable design procedures, it is important to understand the flow patterns in the mixer and settler zones. Computational Fluid Dynamics (CFD) has played a major role in the constant evolution and improvements of this device. During the past thirty years, a large number of investigators have undertaken CFD simulations. All these publications have been carefully and critically analyzed and a coherent picture of the present status has been presented in this review paper. Initially, review of the single phase studies in the annular region has been presented, followed by the separator region. In continuation, the two-phase CFD simulations involving liquid-liquid and gas-liquid flow in the annular as well as separator regions have been reviewed. Suggestions have been made for the future work for bridging the existing knowledge gaps. In particular, emphasis has been given to the application of CFD simulations for the design of this equipment.
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  • 46
    Publication Date: 2013-03-07
    Description: There are two classes of mixing sensitive reactions: competitive-consecutive and competitive-parallel. The yield of desired product from these coupled reactions depends on how fast the reactants are brought together. Recent experimental results have suggested that the mixing effect may depend strongly on the stoichiometry of the reactions. To investigate this, a 1D, dimensionless, reaction-diffusion model at the micromixing scale was developed. Assuming constant mass concentration and mass diffusivities, systems of PDE's were derived on a mass fraction basis for both types of reactions. Two dimensionless reaction rate ratios and a single general Damköhler number emerged from the analysis. The resulting dimensionless equations were used to investigate the effects of mixing, reaction rate ratio, and reaction stoichiometry. As expected, decreasing either the striation thickness or the dimensionless rate ratio maximizes yield, the reaction stoichiometry has a considerable effect on yield, and all three variables interact strongly.
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  • 47
    Publication Date: 2013-03-07
    Description: Composite membranes have been prepared by impregnation of Nafion into the expanded polytetrafluoroethylene (EPTFE) matrix. Nafion loading in the composite membranes was kept constant at 2 mg/cm2. The lower amount of electrolyte per unit area in the composite membranes offers cost advantages compared to conventional membrane of 50 μm thickness with an electrolyte loading of ~9 mg/cm2. Composite membranes (30 μm thickness) were found to have higher thermal stability and mechanical strength compared to the conventional membranes (50 μm thickness). The performance of the membrane electrode assembly made with these composite membranes was comparable to that of the conventional membranes. Single cells fabricated from these MEAs were tested for their performance and durability before scaling them up for large area. The performance of a 20-cell stack of active area 330 cm2 fabricated using these membranes is reported.
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  • 48
    Publication Date: 2013-03-07
    Description: The metal-finishing and tannery industries have been under strong pressure to replace their current wastewater treatment based on a physicochemical process. The electrodialysis process is becoming an interesting alternative for wastewater treatment. Electrodialysis is a membrane separation technique, in which ions are transported from one solution to another through ion-exchange membranes, using an electric field as the driving force. Blends of polystyrene and polyaniline were obtained in order to produce membranes for electrodialysis. The produced membranes were applied in the recovery of baths from the metal-finishing and tannery industries. The parameter for electrodialysis evaluation was the percentage of chromium extraction. The results obtained using these membranes were compared to those obtained with the commercial membrane Nafion 450.
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  • 49
    Publication Date: 2013-03-07
    Description: The present study deals with the removal of phosphorus from wastewater by using oven-dried alum sludge (ODS) as adsorbent that was collected from Al-Qadisiya treatment plant (Iraq); it was heated in an oven at 105∘C for 24 h and then cooled at room temperature. The sludge particles were then crushed to produce a particle size of 0.5–4.75 mm. Two modes of operation are used, batch mode and fixed bed mode, in batch experiment the effect of oven-dried alum sludge doses 10–50 g/L, pH of solution 5–8 with constant initial phosphorus concentration of 5 mg/L, and constant particle size of 0.5 mm were studied. The results showed that the percent removal of phosphorus increases with the increase of oven-dried alum sludge dose, but pH of solution has insignificant effect. Batch kinetics experiments showed that equilibrium time was about 6 days. Adsorption capacity was plotted against equilibrium concentration, and isotherm models (Freundlich, Langmuir, and Freundlich-Langmuir) were used to correlate these results. In the fixed bed isothermal adsorption column, the effect of initial phosphorus concentration (
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  • 50
    Publication Date: 2013-03-07
    Description: The mixing performance in a vessel agitated by an impeller that inclined itself, which is considered one of the typical ways to promote mixing performance by the spatial chaotic mixing, has been investigated experimentally and numerically. The mixing time was measured by the decolorization method and it was found that the inclined impeller could reduce mixing time compared to that obtained by the vertically located impeller in laminar flow region. The effect of eccentric position of inclined impeller on mixing time was also studied and a significant reduction of mixing time was observed. To confirm the experimental results, the velocity profiles were calculated numerically and two novel numerical simulation methods were proposed.
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  • 51
    Publication Date: 2013-03-07
    Description: The electrochemical characteristics of cation-exchange membranes based on polynorbornenes with fluorinated and sulfonated dicarboximide side chain groups were reported. This study was extended to a block copolymer containing structural units with phenyl and 4-oxybenzenesulfonic acid, 2,3,5,6-tetrafluorophenyl moieties replacing the hydrogen atom of the dicarboximide group. A thorough study on the electrochemical characteristics of the membranes involving electromotive forces of concentration cells and proton conductivity is reported. The proton permselectivity of the membranes is also discussed.
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  • 52
    Publication Date: 2012-10-13
    Description: The hydrodynamics of circulating fluidized beds (CFBs) is a complex phenomenon that can drastically vary depending on operational setup and geometrical configuration. A research of the literature shows that studies for the prediction of key variables in CFB systems operating at high temperature still need to be implemented aiming at applications in energy conversion, such as combustion, gasification, or fast pyrolysis of solid fuels. In this work the computational fluid dynamics (CFD) technique was used for modeling and simulation of the hydrodynamics of a preheating gas-solid flow in a cylindrical bed section. For the CFD simulations, the two-fluid approach was used to represent the gas-solid flow with the k-epsilon turbulence model being applied for the gas phase and the kinetic theory of granular flow (KTGF) for the properties of the dispersed phase. The information obtained from a semiempirical model was used to implement the initial condition of the simulation. The CFD results were in accordance with experimental data obtained from a bench-scale CFB system and from predictions of the semiempirical model. The initial condition applied in this work was shown to be a viable alternative to a more common constant solid mass flux boundary condition.
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  • 53
    Publication Date: 2016-01-21
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  • 54
    Publication Date: 2016-01-27
    Description: The ultrasound-assisted extraction (UAE) was initially applied to extract gallic acid from Suaeda glauca Bge. using 70% ethanol as extraction solvent. Temperature, liquid-solid ratio, and extraction time were optimized by response surface methodology (RSM), obtaining maximum levels of gallic acid (6.30 mg·g−1) at 51°C, 19.52 mL·g−1, and 42.68 min, respectively. The obtained model was statistically significant (). The verification experiments at the optimum conditions yielded gallic acid for 6.21 mg·g−1. Subsequently, under optimal conditions, four ionic liquids were used to extract gallic acid from Suaeda glauca Bge. The results indicated that the presence of 1-hexyl-3-methylimidazolium chloride allowed increasing the EE of gallic acid up to 8.90 mg·g−1. This might be interpreted in terms of the molecular interaction between ionic liquid and gallic acid. The use of ionic liquids involves a stronger gallic acid extraction capacity than conventional organic volatile solvents. A promising alternative process is proposed for the extraction of gallic acid of Suaeda glauca Bge.
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  • 55
    Publication Date: 2016-02-24
    Description: Recently, various composites for reducing CO2 emissions have been extensively studied. Because of their high sorption capacity and low cost, alkali metal carbonates are recognized as a potential candidate to capture CO2 from flue gas under moist conditions. However, undesirable effects and characteristics such as high regeneration temperatures or the formation of byproducts lead to high energy costs associated with the desorption process and impede the application of these materials. In this study, we focused on the regeneration temperature of carbon aerogel–potassium carbonate (CA–KC) nanocomposites, where KC nanocrystals were formed in the mesopores of the CAs. We observed that the nanopore size of the original CA plays an important role in decreasing the regeneration temperature and in enhancing the CO2 capture capacity. In particular, 7CA–KC, which was prepared from a CA with 7 nm pores, exhibited excellent performance, reducing the desorption temperature to 380 K and exhibiting a high CO2 capture capacity of 13.0 mmol/g-K2CO3, which is higher than the theoretical value for K2CO3 under moist conditions.
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  • 56
    Publication Date: 2016-02-26
    Description: Adsorption is one of the important treatment methods for the removal of pollutants from wastewater. The determination of rate controlling step in the process is important in the design of the process. Therefore, in the present work, mass transfer studies were done to evaluate the rate-limiting step in the adsorption of phenol from aqueous solution onto Lantana camara. Different mass transfer models were used to find the rate-limiting step and also to find the values of external mass transfer coefficient and diffusion coefficient. The Biot number was found to investigate the importance of external mass transfer to intraparticle diffusion. From the various models studied and the Biot numbers obtained, it was found that the adsorption on Lantana camara was controlled by film diffusion. The sensitivity analysis was performed to study the significance of the model parameters on the adsorption process.
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  • 57
    Publication Date: 2016-02-29
    Description: The prediction of power generated by photovoltaic (PV) panels in different climates is of great importance. The aim of this paper is to predict the output power of a 3.2 kW PV power plant using the MLP-ABC (multilayer perceptron-artificial bee colony) algorithm. Experimental data (ambient temperature, solar radiation, and relative humidity) was gathered at five-minute intervals from Tehran University’s PV Power Plant from September 22nd, 2012, to January 14th, 2013. Following data validation, 10665 data sets, equivalent to 35 days, were used in the analysis. The output power was predicted using the MLP-ABC algorithm with the mean absolute percentage error (MAPE), the mean bias error (MBE), and correlation coefficient (), of 3.7, 3.1, and 94.7%, respectively. The optimized configuration of the network consisted of two hidden layers. The first layer had four neurons and the second had two neurons. A detailed economic analysis is also presented for sunny and cloudy weather conditions using COMFAR III software. A detailed cost analysis indicated that the total investment’s payback period would be 3.83 years in sunny periods and 4.08 years in cloudy periods. The results showed that the solar PV power plant is feasible from an economic point of view in both cloudy and sunny weather conditions.
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  • 58
    Publication Date: 2016-02-29
    Description: Silver (Ag) substituted ZnO thin films were successfully deposited onto glass substrates by spray coating technique. Structure, morphology, and optical properties were evaluated by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometer, respectively. XRD spectra had polycrystalline wurtzite structure; SEM images showed that thin films had different surface morphology at different Ag doping concentration. From transmittance spectra, thin films transparency decreased as well as band gap energy along with increase of Ag doping concentration. Methylene blue (MB) solution was used as a pollutant in the photodegradation studies. Under UV light irradiation, the optimal Ag doping is 25%, with 83% of the decolorizing efficiencies after 3 h irradiation time and apparent constant () about 9.69 × 10−3 min−1.
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  • 59
    Publication Date: 2015-12-02
    Description: In the wake of global warming and rapid fossil fuel depletion, microalgae emerge as promising feedstocks for sustainable biofuel production. Nile red staining acts as a rapid diagnostic tool to measure the amount of biodiesel-convertible lipid that the cells accumulate. There is a need for the development of a more uniform staining procedure. In its first phase, this study examined the dependence of microalgal Nile red fluorescence (Tetraselmis suecica) in terms of its most pertinent staining variables. A quadratic surface model that successfully described the Nile red fluorescence intensity as a composite function of its variables was generated (). Cell concentration was shown to have a significant effect on the fluorescence intensity. Up to a certain threshold, fluorescence intensity was shown to increase with Nile red dye concentration. In its second phase, the study reviewed findings from previous Nile red studies to elucidate some of the fundamental mechanism underlying the diffusion of Nile red dye molecules into the microalgal cells and their subsequent interaction with intracellular lipids. Through the review process, we were able to develop a simple framework that provided a set of guidelines for the standardization of the Nile red staining procedure across different microalgal species.
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  • 60
    Publication Date: 2015-12-04
    Description: In the study the yield and kinetic and thermodynamic parameters of the oil extraction process from Jatropha curcas L. using ethanol as a solvent were evaluated for different temperatures, moisture contents of the solid phase, and particle sizes. The extraction process yield increased with contact time of solid particles with the solvent until reaching equilibrium (saturation of the solvent), for all the temperatures, moisture contents, and average particle sizes. These parameters significantly influenced (95% confidence) the extracted oil yield. A convective mass transfer model was used to simulate the extraction process and estimate the kinetic and thermodynamic parameters. For all conditions evaluated, values of oil yield in the liquid phase close to equilibrium were obtained in approximately 20 min. The variations of enthalpy and entropy were positive, indicating that the process is endothermic and irreversible. Values obtained for the variation in Gibbs free energy showed that the extraction process using ethanol as a solvent is spontaneous and thermodynamically favorable for the moisture content of 0%, where the smaller the average particle size the greater the spontaneity of the process.
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  • 61
    Publication Date: 2015-12-07
    Description: Hydrates of natural gases like methane have become subject of great interest over the last few decades, mainly because of their potential as energy resource. The exploitation of these natural gases from gas hydrates is seen as a promising mean to solve future energetic problems. Furthermore, gas hydrates play an important role in gas transportation and gas storage: in pipelines, particularly in tubes and valves, gas hydrates are formed and obstruct the gas flow. This phenomenon is called “plugging” and causes high operational expenditure as well as precarious safety conditions. In this work, research on the formation of gas hydrates under pipeline-like conditions, with the aim to predict induction times as a mean to evaluate the plugging potential, is described.
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  • 62
    Publication Date: 2012-06-21
    Description: Diesters biolubricant base oil, oleyl 9(12)-hydroxy-10(13)-oleioxy-12(9)-octadecanoate (OLHYOOD) was synthesized based on the esterification reaction of 9,12-hydroxy-10,13-oleioxy-12-octadecanoic acid (HYOOA) with oleyl alcohol (OL) and catalyzed by sulfuric acid (SA). Optimum conditions of the experiment to obtain high yield % of OLHYOOD were predicted at ratio of OL/HYOOA of 2 : 1 mol/mol, ratio of SA/HYOOA of 0.7 : 1 mol/mol, reaction temperature 110°C, and 7 h of reaction time. At this condition, the yield of OLHYOOD was 88.7%. Disappearance of carboxylic acid (C=O) peak has been observed by FTIR with appearance of ester (C=O) peak at 1738 cm-1. 13C, and 1H NMR spectra analyses confirmed the result of OLHYOOD with the appearance of carbon-ester (C=O) chemical shift at 173.93 ppm and at 4.05 ppm for 13C and 1H NMR, respectively. The physicochemical characteristics of the OLHYOOD were also determined, which showed improved low temperature properties (PP) −62°C, viscosity index (VI) at 192 and also increased oxidative stability (OT) up to 215.24°C.
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  • 63
    Publication Date: 2012-06-21
    Description: Processing of dilute liquid streams in the industries like food, agro-, biotechnology, pharmaceuticals, environment, and so forth needs special strategy for the separation and purification of the desired product and for environment friendly disposal of the waste stream. The separation strategy adopted to achieve the goal is extremely important from economic as well as from environmental point of view. In the present paper we have reviewed the various aspects of some selected universal separation strategies such as adsorption, membrane separation, electrophoresis, chromatographic separation, and electroosmosis that are exercised for processing of dilute liquid streams.
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  • 64
    Publication Date: 2012-06-21
    Description: Various quaternary CuInxGa1−xS2 (0≤x≤1) chalcopyrite nanoparticles have been prepared from molecular single-source precursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility. Depending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This method has been used to generate up to 5 g of nanoparticles and up to 150 g from multiple batch reactions with excellent reproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown high reproducibility in nanoparticle size, composition, and bandgap.
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  • 65
    Publication Date: 2012-06-21
    Description: A reduced chemical kinetic model for Titan's atmosphere has been developed. This new model with 18 species and 28 reactions includes the mainfeatures of a more complete scheme, respecting the radiative fluxes. It has been verified against three key elements: a sensitivity analysis, the equilibrium chemical composition using shock tube simulations in CHEMKIN, and the results of computational fluid dynamics (CFDs) simulations.
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  • 66
    Publication Date: 2012-06-21
    Description: The present study examines how climatic conditions and pond design affect the growth performance of microalgae. From January to April of 2011, outdoor batch cultures of Nannochloropsis salina were grown in three replicate 780 L conventional raceways, as well as in an experimental 7500 L algae raceway integrated design (ARID) pond. The ARID culture system utilizes a series of 8–20 cm deep basins and a 1.5 m deep canal to enhance light exposure and mitigate temperature variations and extremes. The ARID culture reached the stationary phase 27 days earlier than the conventional raceways, which can be attributed to its superior temperature management and shallower basins. On a night when the air temperature dropped to −9°C, the water temperature was 18°C higher in the ARID pond than in the conventional raceways. Lipid and fatty acid content ranged from 16 to 25% and from 5 to15%, respectively, as a percentage of AFDW. Palmitic, palmitoleic, and eicosapentaenoic acids comprised the majority of fatty acids. While the ARID culture system achieved nearly double the volumetric productivity relative to the conventional raceways (0.023 versus 0.013 g L−1day−1), areal biomass productivities were of similar magnitude in both pond systems (3.47 versus 3.34 g m−2day−1), suggesting that the ARID pond design has to be further optimized, most likely by increasing the culture depth or operating at higher cell densities while maintaining adequate mixing.
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  • 67
    Publication Date: 2012-06-21
    Description: In this study, the effects of ethanolic KOH concentration, reaction temperature, and reaction time to free fatty acid (FFA) percentage were investigated. D-optimal design was employed to study significance of these factors and optimum condition for the technique predicted and evaluated. The optimum conditions for maximum FFA% were achieved when 1.75 M ethanolic KOH concentration was used as the catalyst, reaction temperature of 65°C, and reaction time of 2.0 h. This study showed that ethanolic KOH concentration was significant variable for saponification of J. curcas seed oil. In an 18-point experimental design, percentage of FFA for saponification of J. curcas seed oil can be raised from 1.89% to 102.2%.
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  • 68
    Publication Date: 2012-06-21
    Description: Heavy metals are among the most important sorts of contaminant in the environment. Several methods already used to clean up the environment from these kinds of contaminants, but most of them are costly and difficult to get optimum results. Currently, phytoremediation is an effective and affordable technological solution used to extract or remove inactive metals and metal pollutants from contaminated soil and water. This technology is environmental friendly and potentially cost effective. This paper aims to compile some information about heavy metals of arsenic, lead, and mercury (As, Pb, and Hg) sources, effects and their treatment. It also reviews deeply about phytoremediation technology, including the heavy metal uptake mechanisms and several research studies associated about the topics. Additionally, it describes several sources and the effects of As, Pb, and Hg on the environment, the advantages of this kind of technology for reducing them, and also heavy metal uptake mechanisms in phytoremediation technology as well as the factors affecting the uptake mechanisms. Some recommended plants which are commonly used in phytoremediation and their capability to reduce the contaminant are also reported.
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  • 69
    Publication Date: 2012-06-21
    Description: A model-based predictive control system is designed for a copolymerization reactor. These processes typically have such a high nonlinear dynamic behavior to make practically ineffective the conventional control techniques, still so widespread in process and polymer industries. A predictive controller is adopted in this work, given the success this family of controllers is having in many chemical processes and oil refineries, especially due to their possibility of including bounds on both manipulated and controlled variables. The solution copolymerization of methyl methacrylate with vinyl acetate in a continuous stirred tank reactor is considered as an industrial case study for the analysis of the predictive control robustness in the field of petrochemical and polymer production. Both regulatory and servo problems scenarios are considered to check tangible benefits deriving from model-based predictive controller implementation.
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  • 70
    Publication Date: 2012-06-21
    Description: The aim of this research was to determine the influence of temperature, agitation, sludge concentration, and solids retention time (SRT) to obtain readily biodegradable organic matter on primary sludge (PS) fermentation, which would be used as substrate in a biological nutrient removal (BNR) process. Stirring and heating the sludge as well as increasing SRT improved the PS fermentation, producing a large amount of soluble chemical oxygen demand (SCOD). The influence of each operational parameter on PS hydrolysis was observed clearly. A great performance on SCOD production was obtained when the PS was stirred and heated for 3 days. However, PS concentration did not affect the fermentation. Sludge agitation is a simple process with minimal energy consumption. Warming the sludge is very interesting in those plants with anaerobic digestion, where heat energy is obtained from biogas. Therefore, PS fermentation can be improved with a minimum investment and leveraging existing resources in a wastewater treatment plant (WWTP). Fermenter volume can also be reduced if sludge is being heated and stirred during fermentation.
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  • 71
    Publication Date: 2012-06-21
    Description: One of the conventional kraft pulp mills produce crude tall oil which is a mixture of free fatty acids, resin acids, sterols, terpenoid compounds, and many others. This study is devoted to the issue of direct transformation of crude tall oil in a mixture with straight-run atmospheric gas oil to liquid fuels using three different commercial hydrotreating catalysts. Diesel fuel production is an alternative to incineration of these materials. High catalytic activity was achieved for all tested catalysts in temperature range 360–380°C, under 5.5 MPa hydrogen pressure and ratio H2/feedstock 500–1000 l/l. Crude tall oil can be converted to diesel oil component via simultaneous refining with straight-run atmospheric gas oil on NiMo/Al2O3 and NiW/Al2O3-zeolite catalysts. All tested catalysts had very good hydrodenitrogenation activity and high liquid yield were at tested conditions.
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  • 72
    Publication Date: 2012-06-21
    Description: The response surface methodology and canonical analysis were employed to find the most suitable conditions for Lactobacillus helveticus to produce lactic acid from cheese whey in batch fermentation. The analyzed variables were temperature, pH, and the concentrations of lactose and yeast extract. The experiments were carried out according to a central composite design with three center points. An empiric equation that correlated the concentration of lactic acid with the independent variables was proposed. The optimal conditions determined by the canonical analysis of the fitted model were 40°C, pH 6.8, 82 g/L of lactose, and 23.36 g/L of yeast extract. At this point, the lactic acid concentration reached 59.38 g/L. A subsequent fermentation, carried out under optimal conditions, confirmed the product concentration predicted by the adjusted model. This concentration of lactic acid is the highest ever reported for Lactobacillus helveticus ATCC 15009 in batch process using cheese whey as substrate.
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  • 73
    Publication Date: 2012-06-21
    Description: Lignin forms an important part of lignocellulosic biomass and is an abundantly available residue. It is a potential renewable source of phenol. Liquefaction of enzymatic hydrolysis lignin as well as catalytical hydrodeoxygenation of the main intermediates in the degradation of lignin, that is, catechol and guaiacol, was studied. The cleavage of the ether bonds, which are abundant in the molecular structure of lignin, can be realised in near-critical water (573 to 673 K, 20 to 30 MPa). Hydrothermal treatment in this context provides high selectivity in respect to hydroxybenzenes, especially catechol. RANEY Nickel was found to be an adequate catalyst for hydrodeoxygenation. Although it does not influence the cleavage of ether bonds, RANEY Nickel favours the production of phenol from both lignin and catechol. The main product from hydrodeoxygenation of guaiacol with RANEY Nickel was cyclohexanol. Reaction mechanism and kinetics of the degradation of guaiacol were explored.
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  • 74
    Publication Date: 2012-06-21
    Description: This study was undertaken to identify the relevant bending points in ORP, pH, and DO profiles in ammonia removal through online monitoring. A novelty BAF system as newl application for drinking water treatment that equipped with ORP, pH, DO NH4 + and NO3 − sensors was used. Two types of polluted drinking water strength (low and high strength) with various NH4 + concentrations and aeration flow were treated at a fixed-time reaction of 24 h. Experiments were conducted at four track studies (TS) of TS1 (NH4 += 50 mg/L, aeration = 0.3 L/min), TS2 (NH4 + = 100 mg/L, aeration = 2.0 L/min), TS3 (NH4 += 100 mg/L, no aeration) and TS4 (NH4 += 10 mg/L, aeration = 0.1 L/min). The results showed that the removal of NH4 + was more than 95% for TS1, TS2, and TS4. From the online monitoring performances, DO elbow and ammonia valley appeared in ORP and pH profiles, respectively. Similarly, new positive plateaus were observed in DO, indicating that the nitrifiers stopped to consume the DO after NH4 + was completely removed. Hence, based on the bending points, the aeration system is possible to be automatically stopped just after DO elbow and ammonia valley appears in order to save the energy consumption and to shorten the time demands for the drinking water treatment process.
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  • 75
    Publication Date: 2012-06-21
    Description: A general overall feasibility methodology of batch reactive distillation of multireaction systems is developed to study all the possible configurations of batch reactive distillation. The general model equations are derived for multireaction system with any number of chemical equilibrium-limited reactions and for any number of components. The present methodology is demonstrated with the detailed study of the transesterification of dimethyl carbonate in two reversible cascade reactions in batch reactive distillation process. Pure methanol is produced as distillate, and pure diethyl carbonate is produced at the bottom simultaneously in middle-vessel column; in each section, continuous feeding of ethanol is necessary. The results of feasibility study are successfully validated by rigorous simulations.
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  • 76
    Publication Date: 2012-06-21
    Description: Stearic acid solid lipid nanoparticles were prepared according to a new technique, called coacervation. The main goal of this experimental work was the entrapment of peptide drugs into SLN, which is a difficult task, since their chemical characteristics (molecular weight, hydrophilicity, and stability) hamper peptide-containing formulations. Insulin and leuprolide, chosen as model peptide drugs, were encapsulated within nanoparticles after hydrophobic ion pairing with anionic surfactants. Peptide integrity was maintained after encapsulation, and nanoparticles can act in vitro as a sustained release system for peptide.
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  • 77
    Publication Date: 2012-06-21
    Description: Particle size and morphology are important properties of pharmaceutical particles. Preparation of microparticles with uniform particle size and morphology is necessary in order to systematically relate these properties to the release behavior and other functionalities such as drug encapsulation and dissolution. In this study, we successfully prepared monodisperse, nonagglomerated chitosan microparticles in a single step by a novel spray-drying technique. The control of particle size and morphology of spray-dried microparticles was investigated experimentally. Microparticles with larger particle size can be produced when chitosan precursor of higher concentration was used. Storage time of chitosan precursor, drying temperature, and addition of lactose were shown to be crucial parameters that affect the particle morphology. Appropriate choice of the drying temperature and precursor storage time permitted control of the particle morphology, ranging from nearly spherical to cap-shaped. Surface characteristics of the particles can be finely tuned by the amount of lactose added into the chitosan precursor.
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  • 78
    Publication Date: 2012-06-21
    Description: The potential use of acid-treated biomass of Trichoderma gamsii to remove hexavalent chromium ions from electroplating industrial effluent was evaluated. Electroplating industrial effluent contaminated with 5000 mg/L of Cr(VI) ions, collected from industrial estate of Gujarat, India, was mixed with acid-treated biomass of T. gamsii at biomass dose of 10 mg/mL. Effect of contact time and initial Cr(VI) ions was studied. The biosorption of Cr(VI) ions attained equilibrium at time interval of 240 minutes with maximum removal of 87% at preadjusted initial Cr(VI) concentration of 100 mg/L. The biosorption of Cr(VI) ions by biomass of T. gamsii increased as the initial Cr(VI) ion concentration of the effluent was adjusted in increasing range of 100–500 mg/L. At 500 mg/L, initial Cr(VI) concentration, acid-treated biomass of T. gamsii showed maximum biosorption capacity of 44.8 mg/g biomass from electroplating effluent. The Cr(VI) biosorption data were analysed using adsorption isotherms, that is, Freundlich and Langmuir isotherm. The correlation regression coefficients (R2) and isotherm constant values show that the biosorption process follows Freundlich isotherm (R2>0.9, n>1, and Kf=8.3). The kinetic study shows that biosorption of Cr(VI) ions by acid-treated biomass of T. gamsii follows pseudo-second-order rate of reaction at increasing concentration of Cr(VI). In conclusion, acid-treated biomass of T. gamsii can be used as biosorbent for Cr(VI) ions removal from Cr(VI)-contaminated wastewater generated by industries.
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  • 79
    Publication Date: 2012-06-21
    Description: TiO2/ZnO nanocomposites were prepared by the sol-gel method with and without addatives such as carboxy methyl cellulose (CMC), poly(ethylene glycol) (PEG), polyvinylpyrrolidon, (PVP), and hydroxylpropylcellulose (HPC). The characteristics of the prepared TiO2/ZnO nanocomposites were identified by IR spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) methods. The additives have a significant effect on the particle size distribution and photocatalytic activity of TiO2/ZnO nanocomposites. The photocatalytic activity of the synthesized nanocomposites was investigated for decolorization of methyl orange (MO) in water under UV-irradiation in a batch reactor and the results showed that the photocatalytic activity of the nanocomposites have been increased by CMC, PEG, PVP, and HPC, respectively. SEM has shown that the particle size distribution of TiO2/ZnO nanocomposite in the presence of HPC was better than the other samples.
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  • 80
    Publication Date: 2012-06-21
    Description: Dehydration of sugars to 5-hydroxymethylfurfural (HMF) has recently been under intensive study by a multitude of research groups. On the other hand, when lignocellulosic biomass is applied as the starting material, very few studies can be found in the open literature. The direct synthesis of HMF, in line with the idea of “one-pot” synthesis strategy from lignocellulose, is demanding since the overall process should encompass dissolution, hydrolysis, and dehydration steps in a single processing unit. Ionic liquid-assisted methods to produce hydroxymethyl-furfural directly from lignocellulosic biomass are reported here together with a short overview of the most important biofuels. In reality, HMF is not suitable to be used as a single-component fuel as such, and, consequently, methods to produce HMF derivatives suitable as liquid fuels are reported.
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  • 81
    Publication Date: 2012-06-21
    Description: The generation of test gas from pure liquids has a wide variety of applications in laboratory and field experiments, for which the quality of the test gas is of significance. Therefore, various methods for test gas generation have been designed. Each method has unique advantages and disadvantages. Thus, a short overview is presented within the scope of this paper. Furthermore, a common bubbler system is presented, which was built to generate test gas from volatile organic compounds for experimental usage in laboratory applications. An analysis is conducted with respect to the generated concentrations at different temperatures and flow rates of the diluting gas. Accuracy and stability of this method are investigated.
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  • 82
    Publication Date: 2012-06-21
    Description: Compositions having the general formula BaTiO3-CuO+x wt% Ag, where x=0,1,1.5, and 2 have been prepared by solid state ceramic processing and sintered at 500 and 700∘C for 5 h. Thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), infrared absorption spectra (IR), and scanning electron microscopy (SEM) were used to characterize the obtained sensor pellets. It was found that no solid state reaction took place between BaTiO3 and CuO during sintering process. The sensitivity of the prepared sensors to CO2 gas increases with increasing sintering temperature and Ag content. The correlation between Ag content at different sintering temperature and structure characterization is discussed.
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  • 83
    Publication Date: 2012-06-21
    Description: A particle-laden flow inside solid gas cyclones has been studied using computational fluid dynamics (CFD). The effects of high temperatures and different particle loadings have been investigated. The Reynolds stress (RSM) model-predicted results, in the case of pure gas, are within engineering accuracy even at high temperatures. Using the granular mixture model for the cases of particle-laden flow, discrepancies occurred at relatively high loadings (up to 0.5 kg/m3). Since the pressure drop is strongly related to the friction inside the cyclone body, the concept of entropy generation has been employed to detect regions of high frictional effects. Friction has been observed to be important at the vortex finder wall, the bottom of the conical-part wall, and the interface separating the outer and the core streams. The discrepancies between the present numerical simulation and the experimental results taken from the existing literature, which are caused by the mixture and turbulence models simplifying assumptions, are discussed in this paper.
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  • 84
    Publication Date: 2012-06-21
    Description: Palladium(II) iodide is used as a catalyst in the phenylacetylene oxidative carbonylation reaction that has demonstrated oscillatory behaviour in both pH and heat of reaction. In an attempt to extract the reaction network responsible for the oscillatory nature of this reaction, the system was divided into smaller parts and they were studied. This paper focuses on understanding the reaction network responsible for the initial reactions of palladium(II) iodide within this oscillatory reaction. The species researched include methanol, palladium(II) iodide, potassium iodide, and carbon monoxide. Several chemical reactions were considered and applied in a modelling study. The study revealed the significant role played by traces of water contained in the standard HPLC grade methanol used.
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  • 85
    Publication Date: 2012-06-21
    Description: Five reaction schemes are suggested for the initiated nonbranched-chain addition of free radicals to the multiple bonds of alkenes, formaldehyde, and oxygen. The schemes include reactions competing with chain propagation through a reactive free radical. The chain evolution stage in these schemes involves three or four types of free radicals. One of them—CH2=C(CH3)C•H2, CH2=CHC•HOH, HC•=O, o−CH3C6H4CH2O4•, or HO4•—is relatively low-reactive and inhibits the chain process by shortening of the kinetic chain length. Based on the suggested schemes, nine rate equations containing one to three parameters to be determined directly are set up using quasi-steady-state treatment. These equations provide good fits for the nonmonotonic (peaking) dependences of the formation rates of the molecular addition products (1 : 1 adducts) on the concentration of the unsaturated component in liquid homogeneous binary systems consisting of a saturated component (hydrocarbon, alcohol, etc.) and an unsaturated component (olefin, formaldehyde, or dioxygen). The unsaturated compound in these systems is both a reactant and an autoinhibitor generating low-reactive free radicals. A similar kinetic description is applicable to nonbranched-chain free-radical hydrogen oxidation. The energetics of the key radical-molecule reactions is considered.
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  • 86
    Publication Date: 2012-06-21
    Description: Fermentation processes by nature are complex, time-varying, and highly nonlinear. As dynamic systems their modeling and further high-quality control are a serious challenge. The conventional optimization methods cannot overcome the fermentation processes peculiarities and do not lead to a satisfying solution. As an alternative, genetic algorithms as a stochastic global optimization method can be applied. For the purpose of parameter identification of a fed-batch cultivation of S. cerevisiae altogether four kinds of simple and four kinds of multipopulation genetic algorithms have been considered. Each of them is characterized with a different sequence of implementation of main genetic operators, namely, selection, crossover, and mutation. The influence of the most important genetic algorithm parameters—generation gap, crossover, and mutation rates has—been investigated too. Among the considered genetic algorithm parameters, generation gap influences most significantly the algorithm convergence time, saving up to 40% of time without affecting the model accuracy.
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  • 87
    Publication Date: 2012-06-21
    Description: In the experiment, nanoparticles of 35 nm Al and 100 nm Al powders, respectively, formed particles with average sizes of 161 nm and 167 nm in agglomeration. The characteristics of dust cloud explosions with the two powder sizes, 35 nm and 100 nm, revealed considerable differences, as shown here: (dp/dt)max-35 nm = 1254 bar/s, (dp/dt)max-100 nm = 1105 bar/s; Pmax-35 nm = 7.5 bar, Pmax-100 nm = 12.3 bar, and MEC-35 nm = 40 g/m3, MEC-100 nm = 50 g/m3. The reason of Pmax-35 nm value is smaller than Pmax-100 nm may be due to agglomeration. From an analysis of the explosive residue, the study found that nanoparticles of 35 nm Al powder became filamentous strands after an explosion, where most of 100 nm Al nanoparticles maintained a spherical structure, This may be because the initial melting temperature of 35 nm Al is 435.71°C, while that for 100 nm Al is 523.58°C, higher by 87.87°C. This study discovered that explosive property between the 35 nm Al and 100 nm Al powders after agglomeration were different.
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  • 88
    Publication Date: 2012-06-21
    Description: As with any situation that involves economical risk refineries may share their risk with insurers. The decision process generally includes modelling to determine to which extent the process area can be damaged. On the extreme end of modelling the so-called Estimated Maximum Loss (EML) scenarios are found. These scenarios predict the maximum loss a particular installation can sustain. Unfortunately no standard model for this exists. Thus the insurers reach different results due to applying different models and different assumptions. Therefore, a study has been conducted on a case in a Swedish refinery where several scenarios previously had been modelled by two different insurance brokers using two different softwares, ExTool and SLAM. This study reviews the concept of EML and analyses the used models to see which parameters are most uncertain. Also a third model, EFFECTS, was employed in an attempt to reach a conclusion with higher reliability.
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  • 89
    Publication Date: 2012-06-21
    Description: Density, surface tension and refractive index were determined for the binary mixture of catalytic deactivated compounds with 1-ethyl-3-methylimidazolium thiocyanate {[EMIM][SCN]} at temperature of (298.15 to 323.15) K. For all the compounds with ILs, the densities varied linearly in the entire mole fraction with increasing temperature. From the obtained data, the excess molar volume and deviation of surface tension and refractive index have been calculated. A strong interaction was found between similar (cation-thiophene or cation-pyrrole) compounds. The interaction of IL with dissimilar compounds such as indoline and quinoline and other multiple ring compounds was found to strongly depend on the composition of IL at any temperatures. For the mixtures, the surface tension decreases in the order of: thiophene > quinoline > pyridine > indoline > pyrrole > water. In general from the excess volume studies, the IL-sulphur/nitrogen mixture has stronger interaction as compared to IL-IL, thiophene-thiophene or pyrrole-pyrrole interaction. The deviation of surface tension was found to be inversely proportional to deviation of refractive index. The quantum chemical based COSMO-RS was used to predict the non-ideal liquid phase activity coefficient for all mixtures. It indicated an inverse relation between activity coefficient and excess molar volumes.
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  • 90
    Publication Date: 2012-06-21
    Description: This paper summarizes some applications of ultrasonic vibrations regarding heat transfer enhancement techniques. Research literature is reviewed, with special attention to examples for which ultrasonic technology was used alongside a conventional heat transfer process in order to enhance it. In several industrial applications, the use of ultrasound is often a way to increase productivity in the process itself, but also to take advantage of various subsequent phenomena. The relevant example brought forward here concerns heat exchangers, where it was found that ultrasound not only increases heat transfer rates, but might also be a solution to fouling reduction.
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  • 91
    Publication Date: 2012-06-21
    Description: Encapsulation of menthol in beeswax was prepared by a modified particles from gas-saturated solutions (PGSS) process with controlling the gas-saturated solution flow rate. Menthol/beeswax particles with size in the range of 2–50 μm were produced. The effects of the process conditions, namely, the pre-expansion pressure, pre-expansion temperature, gas-saturated solution flow rate, and menthol composition, on the particle size, particle size distribution, and menthol encapsulation rate were investigated. Results indicated that in the range of studied conditions, increase of the pressure, decrease of the gas-saturated solution flow rate, and decrease of the menthol mass fraction can decrease the particle size and narrow particle size distribution of the produced menthol/beeswax microparticles. An N2-blowing method was proposed to measure the menthol release from the menthol/beeswax microparticles. Results showed that the microparticles have obvious protection of menthol from its volatilization loss.
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  • 92
    Publication Date: 2019
    Description: This research describes the photocatalytic design for oil removal from produced water. It involves batch and continuous processes. The photocatalytic degradation of oil has been conducted in glass reactors. The effects of nano-TiO2 concentration, the number of lamps, and the time of radiation were studied in the batch system, while in the continuous treatment, the number of lamps, the direction of light radiation, and the time of processes were studied. The results showed that all the oil was removed in the batch system and the maximum percentage of oil removal was 71% in the continuous system.
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  • 93
    Publication Date: 2019
    Description: The present study is aimed at using one of the most promising methods called reactive extraction to extract succinic acid from aqueous solution by using N,N-dioctyloctan-1-amine in biodiesel as diluent made from sunflower oil, rice bran oil, sesame oil, and karanji oil. The results of extraction studies with the diluents (physical) showed their inability to recover any acid by themselves. In reactive extraction, the organic phase extracting power solely depends on tri-n-octylamine. The ranges of the distribution coefficient are found as 7.62–18.12 for sunflower oil biodiesel, 8.33–17.45 for rice bran oil biodiesel, 7.0–17.67 for sesame oil biodiesel, and 9.85–21.36 for karanji oil biodiesel. The ranges of the loading ratio are 0.1–3.0 for sunflower oil biodiesel, 0.1–2.9 for rice bran oil biodiesel, 0.2–2.9 for sesame oil biodiesel, and 0.1–2.9 for karanji oil biodiesel. The karanji and sunflower oil showed higher values of distribution coefficient (KD) over rice bran oil and sesame oil which might be due to presence of both C20 and special fatty acids. The results show that biogenous diluents along with N,N-dioctyloctan-1-amine as extractant form a nontoxic and viable option for the extraction of succinic acid in the binary phase system.
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  • 94
    Publication Date: 2019
    Description: This study provided a basis for new possibilities concerning the use of the sugarcane bagasse ash as a green pozzolanic addition to the Portland cement composite. To that effect, a simple micronization method using air jet milling without any other additional thermal procedure was used to control the characteristics of ash particles. This procedure not only maintains the required characteristics of the residues but can also improve some of them. Sugarcane bagasse ash is a residue produced on large scale in Brazil by ethanol and sugar plants as a result of the burning of sugarcane bagasse in energy cogeneration. The residue used in this study was initially characterized by scanning electron microscopy, granulometric and specific mass analyses, N2 adsorption measurements, X-ray diffraction, X-ray fluorescence spectroscopy, and thermogravimetric analysis with differential thermal analysis. Pozzolanic ash activity was evaluated according to the axial compressive strength at 28 days and the modified Chapelle methods. The results showed that the milling fly sugarcane bagasse ash samples presented satisfactory pozzolanic activity.
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  • 95
    Publication Date: 2014-01-20
    Description: The esterification of oleic acid in a continuous catalyst-free process using compressed ethanol was investigated in the present study. Experiments were performed in a tubular reactor and variables investigated were temperature, pressure, and oleic acid to ethanol molar ratio for different residence time. Results demonstrated that temperature, in the range of 473 K to 573 K, and pressure had a positive effect on fatty acid ethyl esters (FAEE) production. In the experimental range investigated, high conversions can be obtained at low ethanol concentrations in the reaction medium and it was observed that oleic acid to ethanol molar ratios greater than 1 : 6 show no significant increase in conversion. Nonnegligible reaction conversions (〉90%) were achieved at 573 K, 20 MPa, oleic acid to ethanol molar ratio of 1 : 6, and 20 minutes of residence time.
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  • 96
    Publication Date: 2014-01-17
    Description: This study experimentally investigates the interaction between rising bubbles and swirling water flow imposed around the central (vertical) axis of a bubble plume in a cylindrical water tank. Small air bubbles are successively released from the bottom of the tank to generate a bubble plume, and a stirring disc at the bottom of the tank is rotated to impose a swirling water flow around the central axis of the bubble plume. The bubbles disperse further with the increasing rotational speed of the stirring disc. Some bubbles shift toward the central axis of the swirling flow when is high. The nondimensional swirling velocity of water reduces with increasing bubble flow rate when is lower than a certain value. However, it is less affected by the bubbles when is higher. The precessional amplitude for the upper end of the vortex core increases due to the presence of the bubbles. With increasing , the nondimensional precessional velocity decreases, and the bubble effect also reduces.
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  • 97
    Publication Date: 2014-01-23
    Description: A Wiener-Laguerre model with artificial neural network (ANN) as its nonlinear static part was employed to describe the dynamic behavior of a sequencing batch reactor (SBR) used for the treatment of dye-containing wastewater. The model was developed based on the experimental data obtained from the treatment of an effluent containing a reactive textile azo dye, Cibacron yellow FN-2R, by Sphingomonas paucimobilis bacterium. The influent COD, MLVSS, and reaction time were selected as the process inputs and the effluent COD and BOD as the process outputs. The best possible result for the discrete pole parameter was . In order to adjust the parameters of ANN, the Levenberg-Marquardt (LM) algorithm was employed. The results predicted by the model were compared to the experimental data and showed a high correlation with and a low mean absolute error (MAE). The results from this study reveal that the developed model is accurate and efficacious in predicting COD and BOD parameters of the dye-containing wastewater treated by SBR. The proposed modeling approach can be applied to other industrial wastewater treatment systems to predict effluent characteristics.
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  • 98
    Publication Date: 2013-10-11
    Description: Pretreatment of lignocellulose has received considerable research globally due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. Some of the most promising pretreatment methods require the application of chemicals such as acids, alkali, salts, oxidants, and solvents. Thus, advances in research have enabled the development and integration of chemical-based pretreatment into proprietary ethanol production technologies in several pilot and demonstration plants globally, with potential to scale-up to commercial levels. This paper reviews known and emerging chemical pretreatment methods, highlighting recent findings and process innovations developed to offset inherent challenges via a range of interventions, notably, the combination of chemical pretreatment with other methods to improve carbohydrate preservation, reduce formation of degradation products, achieve high sugar yields at mild reaction conditions, reduce solvent loads and enzyme dose, reduce waste generation, and improve recovery of biomass components in pure forms. The use of chemicals such as ionic liquids, NMMO, and sulphite are promising once challenges in solvent recovery are overcome. For developing countries, alkali-based methods are relatively easy to deploy in decentralized, low-tech systems owing to advantages such as the requirement of simple reactors and the ease of operation.
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  • 99
    Publication Date: 2014-01-31
    Description: This present study shows a comprehensive 2D numerical model for removal of CO2 in a polypropylene (PP) hollow fiber membrane contactor (HFMC) using the computational fluid dynamics (CFD) method. Monoethanolamine (MEA) solution was used as the liquid absorbent in a nonwetting mode. The simulation results represented that higher liquid velocity and concentration and lower gas velocity and concentration led to higher percent of CO2 removal. The most proper parameters for CO2 removal were less than 1 mol m−3 gas concentration and 0.2 m s−1 gas flow rate, and for MEA the values were above 8 mol m−3 concentration and approximately 1 m s−1 liquid velocity. Furthermore, the model was validated with the experiment results. Therefore, the modeling results provided references to the selection of absorbents and operation parameters in the experimental study and pilot-scale applications.
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  • 100
    Publication Date: 2014-02-24
    Description: Pore-expanded ordered mesoporous carbons with 2D hexagonal mesostructure were synthesized by a simple nanocasting process. We adopted sucrose as carbon precursors, mesoporous silica materials SBA-15 as the hard templates, and hexane as micelle swelling agents. The pore size distribution of OMCs was narrow and centered at 5.4 nm, which is larger than the upper limit of pore diameters typically reported for CMK-3. The BET surface area and mesopore volume of PE-CMK-3 can reach to 1213.47 /g and 1.56 /g, respectively, indicating that choosing large pore size materials as template is good for preparation of high performance of OMCs.
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