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Abstract Poly(vinyl alcohol) (PVA) / modified carbon nanotubes (CNTs) mixed matrix membranes (MMMs) were prepared to study the pervaporation (PV) dehydration of aqueous azeotrope isopropanol mixture. CNTs were modified by wrapping... more
Abstract Poly(vinyl alcohol) (PVA) / modified carbon nanotubes (CNTs) mixed matrix membranes (MMMs) were prepared to study the pervaporation (PV) dehydration of aqueous azeotrope isopropanol mixture. CNTs were modified by wrapping different amount (5–14 wt%) of poly(styrenesulfonate) (PSSA) and poly(vinylpyrrolidone) (PVP) on CNT respectively. ATR, XRD, FESEM, TGA and tensile tests were used to characterize the modified carbon nanotubes and the membranes. For carbon nanotubes wrapped lower amount of poly(styrenesulfonate), the pervaporation results showed that the separation factor remarkably increased and the flux slightly decreased by increasing the content of the modified nanotubes from 0 to 3 wt%, while a reverse trend was observed with further incorporation of the nanotubes up to 5 wt%. Interestingly, increasing poly(styrenesulfonate) density around nanotubes’ sidewalls led to non-ideal effects such as interchain coiling of poly(styrenesulfonate) and formation of rigidified coiled-coil aggregations, so the best PV results were achieved at lower wrapping of poly(styrenesulfonate). However, wrapping nanotubes by poly(vinylpyrrolidone) resulted in fabrication of nanocomposites without evidence of defects or agglomerations and enhanced thermal and mechanical properties. Among all prepared membranes, the best PSI (303) was obtained by embedding 4 wt% of poly(vinylpyrrolidone)-wrapped-nanotubes into poly (vinyl alcohol) that could be attributed to good compatibility and interactions between the fillers and the matrix. Hydrogen bonding between carbonyl groups of poly(vinylpyrrolidone) and hydroxyl groups of poly(vinyl alcohol), formation of hydrophilic channels and helical wrapping of poly(vinylpyrrolidone) chains instead of interchain coiling were responsible for the observed improvement in separation performance of the membranes containing PVP-wrapped-CNTs.
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The presented paper describes an experimental study to reduce electrical conductivity (EC) of composting leachate-polluted water by using electrodialysis (ED) process. High efficiency, simple operation, low waste generation and... more
The presented paper describes an experimental study to reduce electrical conductivity (EC) of composting leachate-polluted water by using electrodialysis (ED) process. High efficiency, simple operation, low waste generation and selectivity are considered as major advantageous of applying ED process. Along with evaluation of ED method for desalination, the possibility of the process for COD (chemical oxygen demand) removal was also studied. The impact of- applied voltage, feed concentration and process time on ED performances were investigated. Increasing of the applied voltage and decrease of feed concentration enhanced the reduction of EC and improved the COD removal from the sample. At optimal condition (Voltage=10 Volt, feed solution=Cf/4 and time operation=120 min), the reduction of EC and COD removal were 92.7%, and 83.8%, respectively. Applying higher voltage and using more feed solution concentrations resulted in more energy consumption. The obtained results showed that ED me...
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In this study, the performance of polyimide Matrimid® membranes in the separation of ethylene/ethane and propylene/propane was improved by silica nanoparticles.
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In this study, phosphoric acid doped PBI-Fe2TiO5 nanocomposite membranes were prepared by dispersion of various amounts of Fe2TiO5 nanoparticles in PBI polymer matrix followed by phosphoric acid doping and they were applied into high... more
In this study, phosphoric acid doped PBI-Fe2TiO5 nanocomposite membranes were prepared by dispersion of various amounts of Fe2TiO5 nanoparticles in PBI polymer matrix followed by phosphoric acid doping and they were applied into high temperature proton exchange membrane fuel cells (HT-PEMFCs). Effects of phosphoric acid doping level (PAdop), Fe2TiO5 mass fraction (Wd), and temperature on proton conductivity of the membranes were evaluated. The highest proton conductivity of 0.078 S/cm was obtained for the membranes containing 4 wt% of Fe2TiO5 nanoparticles with the highest value of phosphoric acid doping level (PAdop). Furthermore, a simple semi-empirical model was developed to predict the proton conductivity of the nanocomposite membranes at elevated temperatures (100–180 °C) and dry conditions. The effects of PAdop, Wd, and temperature on proton conductivity of the membranes were accounted in the model. The model was defined based on the volume fraction of free phosphoric acid inside the nanocomposite membrane structure which showed to be a determining factor in proton conduction of the membranes. The obtained proton conductivities by the model at various temperatures and phosphoric acid doping levels were in good agreement with the experimental results (average relative error <4%), indicating the reliability of the model.
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A new kind of nano composite phase change material (NCPCM) was prepared using sodium stearoyl lactylate (SSL) as a surfactant to improve the dispersion of the Al2O3 nano-particles (with 2.5, 5, 7.5, and 10 wt.%) in paraffin with a... more
A new kind of nano composite phase change material (NCPCM) was prepared using sodium stearoyl lactylate (SSL) as a surfactant to improve the dispersion of the Al2O3 nano-particles (with 2.5, 5, 7.5, and 10 wt.%) in paraffin with a SSL/Al2O3 mass ratio of 1:3.5. To evaluate the efficiency of the prepared PCMs, the melting rate of them at a temperature range of 50–60 °C and the effective thermal conductivity values in the solid and liquid states at a temperature range of 25–75 °C were measured using the k-type thermocouple and the transient hot wire technique, respectively. The heat storage behavior of the samples was investigated and their melting temperature, latent heat, and thermal reliability were determined using differential scanning calorimetry (DSC). Results showed that effective thermal conductivity enhancement ratios for the sample containing 10.0 wt.% nano-Al2O3 were 31% and 13% in the solid and liquid states, respectively, which are higher than those reported in similar studies. In addition, melting rate increased by 27%. As expected, all the PCMs showed good thermal reliability after 120 melting/freezing cycles. Based on our results, it may be concluded that the prepared PCMs can be regarded as effective heat storage materials for application in energy storage systems.
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AbstractDetailed results of a comprehensive study on sodium sulfate removal from magnesium stearate (MgSt) aqueous slurry by using batch electrodialysis (ED) process are presented in this paper. Lowered operating costs and water... more
AbstractDetailed results of a comprehensive study on sodium sulfate removal from magnesium stearate (MgSt) aqueous slurry by using batch electrodialysis (ED) process are presented in this paper. Lowered operating costs and water consumption and avoiding from salty waste discharge to the environment were major advantageous of applying ED process in comparison with the conventional methods. The single and interactive effects of operating parameters including applied voltage, initial MgSt concentration, stirring speed, and process time on ED performance were studied by using response surface methodology method. Na recovery, specific power consumption, and sodium ion current efficiency were the objective parameters used to evaluate the ED process performance. The results showed that interaction terms of “voltage-MgSt concentration” and “stirrer speed-voltage” had the most noticeable effects on Na recovery and energy consumption, respectively. Confirmation experiments were performed at the optimum condition pr...
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Chemical Engineering, Chemistry, Analytical Chemistry, Modeling, Separation, and 15 moreExperimental Design, Wastewater, Copper, Heavy Metal, Chromium, Taguchi method, Steady state, Operant Conditioning, Metal ion, Ion Exchange, Electrodialysis, Differential equation, Flow Rate, Experimental Data, and Mass Balance
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ABSTRACT In the current study, the effect of operating conditions including pH value, feed flow and applied pressure on heavy metal removal of a nanofiltration membrane for drinking water production was investigated. A polyamide... more
ABSTRACT In the current study, the effect of operating conditions including pH value, feed flow and applied pressure on heavy metal removal of a nanofiltration membrane for drinking water production was investigated. A polyamide nanofiltration membrane with a net negative surface charge was used for the experiments. In the first series of experiments, single salt solutions containing 1 ppm lead in the form of lead (II) nitrate and 1 ppm nickel in the form of nickel (II) sulfate were used as feed. According to the results, recovery rate, rejection rate and saturation factor were all increased with increasing applied pressure. After that, optimization of operating conditions for maximizing the membrane&amp;#39;s heavy metal rejection performance was performed. According to the results, 93% of nickel and 86% of lead ions were eliminated in the optimum condition. In the next series of experiments, the effect of heavy metal ion concentration on the performance of nanofiltration membrane was studied and finally, the effect of mixed salt solutions on the performance of the membrane was discussed. Results showed that, nickel rejection in the mixed salt solution was lower than its value in the single salt solution; but for the lead ion, rejection performance was improved due to the mixing.
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... DC Montgomery, Design and Analysis of Experiments (3rd ed.), Wiley (1991 ... J. Kerres, W. Cui, R. Disson and W. Neubrand, Development and characterization of crosslinked ionomer membrane based upon sulfinated and sol fonated PSU... more
... DC Montgomery, Design and Analysis of Experiments (3rd ed.), Wiley (1991 ... J. Kerres, W. Cui, R. Disson and W. Neubrand, Development and characterization of crosslinked ionomer membrane based upon sulfinated and sol fonated PSU crosslinked PSU blend membranes by ...
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Mechanical Engineering, Chemical Engineering, Chemistry, Inorganic Chemistry, Catalysis, and 15 moreDecomposition, Scanning Electron Microscopy, Manganese, Heterogeneous Catalysis, Catalyst, Chemical Analysis, Specific surface area, Hydrogen Peroxide, Powder, Differential Thermal Analysis, Perovskite, Thermal Decomposition, Interdisciplinary Engineering, Stoichiometry, and Chemical Engineering Technology
ABSTRACT Textile processing industry generally requires significant amounts of process water for cleaning, rinsing, and dyeing purposes and therefore releases significant amounts of dye polluted waste streams into the environment. In... more
ABSTRACT Textile processing industry generally requires significant amounts of process water for cleaning, rinsing, and dyeing purposes and therefore releases significant amounts of dye polluted waste streams into the environment. In recent years considerable attempts have been made to remove pollutants from these waste streams. One of the promising methods in this regard is membrane filtration. Utilizing this separation method would necessitate the manufacture of effective membranes, such as nanofibrous membranes. Electrospinning is a relatively simple method to produce nanofibers from solutions of different polymers and polymer blends. This paper presents the results of a research on manufacturing a membrane filter by electrospinning Nylon-6 nanofibers on a carbon coated polyurethane substrate and implementing this membrane for dye removal in a filtration system. The membrane sample contained nanofibers with an average diameter of 211 nm. Experiments were run with C.I. Direct yellow 12 as a typical dye pollutant. The effect of coating time, transmembrane pressure, and two different pretreatment methods were investigated and it was observed that by the application of 150ppm coagulant material at 0.75 bar pressure, a filtration efficiency of 98% was achieved.
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Abstract In this work, batch electrodialysis process was used for removal of sodium sulfate from magnesium stearate (MgSt) aqueous slurry. A three-compartment electrodialysis cell equipped with stirrers was designed and implemented to... more
Abstract In this work, batch electrodialysis process was used for removal of sodium sulfate from magnesium stearate (MgSt) aqueous slurry. A three-compartment electrodialysis cell equipped with stirrers was designed and implemented to investigate the effects of various operational parameters – such as applied voltage, MgSt slurry concentration, stirring rate in the feed compartment, and initial NaOH concentration in the cathodic chamber – on the objective functions of desalination rate, specific energy consumption, and sodium ions permeation flux. The obtained results showed that the removal of sodium sulfate and sodium ions permeation flux was enhanced with increasing of applied voltage. However, using higher voltages led to higher specific energy consumption because of energy dissipation in the form of heat generation. No concentration polarization occurred due to using stirrers in the cell compartments and therefore, maximum salt removal of 90% was achieved after 120 min by applying a voltage of 20 V to the cell containing feed solution of 15 wt.% MgSt agitated at 250 rpm. By removing Na + ions in the form of NaOH in the cathodic chamber, the recovered sodium hydroxide can be reused for producing MgSt. At the same time, this process prevents a large volume of water from wasting in comparison with the conventional process for MgSt purification.
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The methodology for the optimization of an electrolytic plant for the production of deuterium is described. The basis of the optimization is to minimize the amount of electricity used in the electrolytic process, and this is assumed to be... more
The methodology for the optimization of an electrolytic plant for the production of deuterium is described. The basis of the optimization is to minimize the amount of electricity used in the electrolytic process, and this is assumed to be proportional to the total amount of gas evolution from the plant. Because the plant consists of two sections, i.e., the feed
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A non-equilibrium model for the numerical simulation of rough rice drying in a deep-bed dryer was evaluated for predicting the variation of average grain moisture content with time. For this purpose, a laboratory scale deep-bed dryer was... more
A non-equilibrium model for the numerical simulation of rough rice drying in a deep-bed dryer was evaluated for predicting the variation of average grain moisture content with time. For this purpose, a laboratory scale deep-bed dryer was designed and built, and the average moisture content of the bed was experimentally determined during the drying process. The effects of temperature, velocity, and relative humidity of the drying air on the average grain moisture content were similarly investigated. Relative error and mean relative error were calculated for the simulation results, and found to be in acceptable range (10%-15%, and <10%, respectively). Results revealed that the temperature of drying air was the most influential parameter on the drying time. Finally, the model proved to be able to predict the variation of the average moisture content with respect to the time with a good accuracy. Citation: Torki Harchegani M., A. Moheb, M. Sadeghi, M. Tohidi, and Z. Naghavi. 2012. Ex...
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Chemical Engineering, Analytical Chemistry, Modeling, Wastewater Treatment, Separation, and 15 moreExperimental Design, Copper, Heavy Metal, Chromium, Zinc, Taguchi method, Steady state, Operant Conditioning, Metal ion, Ion Exchange, Electrodialysis, Differential equation, Flow Rate, Experimental Data, and Mass Balance
Electrodialysis with two different configurations was used for the recovery of NaOH from the waste stream of a MEROX tower. For this purpose, the effects of cell applied voltage and initial Na + concentration in the feed solution on NaOH... more
Electrodialysis with two different configurations was used for the recovery of NaOH from the waste stream of a MEROX tower. For this purpose, the effects of cell applied voltage and initial Na + concentration in the feed solution on NaOH recovery and current efficiency were studied. ...
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The isomorphous substitution of trivalent boron in MFI zeolite structure by applying a novel microwave-assisted “two-stage varying temperature” hydrothermal synthesis method was investigated in this study. The effects of template... more
The isomorphous substitution of trivalent boron in MFI zeolite structure by applying a novel microwave-assisted “two-stage varying temperature” hydrothermal synthesis method was investigated in this study. The effects of template concentration in the batch composition, aging/stirring time, Si/B ratio and second stage time and temperature on the size, morphology and zeolite formation yield were of interest. At the first stage, nucleation and maturation of zeolite precursors was carried out at 80° C for 90min, whereas, the ...
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Engineering, Chemistry, Structure, Microwave, Scanning Electron Microscopy, and 15 moreMorphology, Composition, Molecular Sieve, Recovery, Nucleation, Crystallinity, CHEMICAL SCIENCES, Particle, Crystallite Size, Crystallites, Powder, Hydrothermal Synthesis, Substitution, Homogeneity, and Infrared Spectrometry
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In this study, a non-equilibrium model of the grain fixed deep-bed drying for rough rice has been presented. The model was developed by using mass and energy balance inside a control volume of the bed and a proper rate equation for the... more
In this study, a non-equilibrium model of the grain fixed deep-bed drying for rough rice has been presented. The model was developed by using mass and energy balance inside a control volume of the bed and a proper rate equation for the thin-layer drying. The control volume was composed of two thermodynamical systems: intergranular air and grains. In most of
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Engineering, Thermodynamics, Modeling, Mathematical Modeling, Numerical Simulation, and 12 moreRice, Drying, Energy Balance, PARTIAL DIFFERENTIAL EQUATION, Computer Program, Mathematical Model, Moisture Content, Point of View, Experimental Data, Electrical And Electronic Engineering, Mass Balance, and Thin Layer
ABSTRACT Removal of C.I. Acid Blue 92(AB92) dye by exfoliated graphite (EG) was investigated. Batch adsorption test results proved that EG can remove the dye with a minimum removal efficiency of 70%. Equilibrium isotherm was analyzed by... more
ABSTRACT Removal of C.I. Acid Blue 92(AB92) dye by exfoliated graphite (EG) was investigated. Batch adsorption test results proved that EG can remove the dye with a minimum removal efficiency of 70%. Equilibrium isotherm was analyzed by Freundlich, Langmuir, and Radke–Prausnitz models and the related parameters were estimated. It was found that both Langmuir and Radke–Prausnitz models fit the experimental data satisfactorily. A comprehensive series of column tests were performed to determine the breakthrough curves, and the effects of the feed flow rate, initial dye concentration, and adsorbent dosage on adsorption process were studied. The results showed that the breakthrough time increased in proportion to the increase in the dose of adsorbent, but decreased with increase in flow rate and initial dye concentration. The total uptake of AB92 was found 5.02 (gdye/gEG) at 27 ± 2 °C for the initial concentration of 30 mg L− 1 at 9.6 mL min− 1 feed flow rate. An axial dispersion mathematical model implementing nonlinear isotherm and linear driving force mass transfer assumption were developed for predicting the dynamic behavior of the adsorption column. The results obtained from the mathematical model were in good agreement with the experimental data, which proved the success of the model in predicting the process.Research highlights► Exfoliated graphite was used for C.I. Acid Blue 92 removal from its aqueous solution. ► EG was able to adsorb the dye with maximum removal efficiency of 96%. ► Langmuir and Radke–Prausnitz isotherms could predict the adsorption behavior of EG. ► Adsorption capacity obtained from Langmuir isotherm was relatively low. ► The continuous system was successfully modeled using LDF mass transfer resistance.
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Recovery of sodium hydroxide from waste stream of Merox tower by two different processes of electrodialysis and electrodeionization was studied. During our experiments effects of applied voltage and feed flow rate on current efficiency... more
Recovery of sodium hydroxide from waste stream of Merox tower by two different processes of electrodialysis and electrodeionization was studied. During our experiments effects of applied voltage and feed flow rate on current efficiency for sodium ion, economy of the process ...
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Chromium is one of the major pollutants of water and wastewater; this ion can be seen in different industrial effluents along with other metal ions such as Cu, As [E. Velizarova, A.B. Ribeiro, and L.M. Ottosen, A comparative study on Cu,... more
Chromium is one of the major pollutants of water and wastewater; this ion can be seen in different industrial effluents along with other metal ions such as Cu, As [E. Velizarova, A.B. Ribeiro, and L.M. Ottosen, A comparative study on Cu, Cr and As removal from CCA-treated wood waste by dialytic, Journal of Hazardous Material 94 (2) (2002)147–160]. In the current paper, experimental investigations have been done on the removal of the chromium ions from aqueous solutions which contain Cu2+ as obstructive ion. Electrodialysis is coupled with complexing to recommend a new technique for the elimination of chromium (III) ions. Ethylendiaminetetraacetate acid (EDTA) was used as the complexing agent. The effect of different operating conditions (feed flow rate, voltage or current density, the ratio of the chromium (III) concentration to the copper concentration, EDTA molar ratio to Cr (III) and pH of the feed) on the removal of chromium ions was investigated. The Taguchi method was implied to design the experiments. The optimum operating conditions were determined using the analysis of variance (ANOVA) method. The proposed method resulted in relatively high chromium removal (95% Cr (VI) and 87% Cr (III)) at the optimum operating conditions.
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Single phase nanocrystalline La0.6Ca0.4MnO3 powder was synthesized by both the usual and a modified citrate gel precursor method, and the effects on the formation of homogeneous nano-sized powder with a perovskite structure were... more
Single phase nanocrystalline La0.6Ca0.4MnO3 powder was synthesized by both the usual and a modified citrate gel precursor method, and the effects on the formation of homogeneous nano-sized powder with a perovskite structure were investigated. In the modified method, single phase La0.6Ca0.4MnO3 powder with an average particle size of 17.2 nm was obtained when the powder was pyrolyzed at 520°C for 2 h. Its specific surface area was 40.7 m2 g−1, about 4-fold larger than that of powder made by the usual citrate gel method.