Full article
Reaction Engineering, Kinetics and Catalysts,
Z. Shojaei; E. Iravani; M.A. Moosavian; M. Torab-Mostaedi
Volume 13, Issue 2 , Spring 2016, Pages 3-21
Abstract
Adsorption of Ce(III) from aqueous solution by amino phosphate modified nano TiO2 was investigated. Effects of pH of solution, adsorbent dose, contact time, initial metal concentration and temperature were examined. Experimental data were fitted well by the pseudo second order model. Adsorption was well ...
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Adsorption of Ce(III) from aqueous solution by amino phosphate modified nano TiO2 was investigated. Effects of pH of solution, adsorbent dose, contact time, initial metal concentration and temperature were examined. Experimental data were fitted well by the pseudo second order model. Adsorption was well described by Freundlich isotherm model with a maximum adsorption capacity of 25 mg g-1. According to the obtained thermodynamic parameters, the adsorption was a spontaneous and endothermic process. Effect of interfering cations was studied. The presence of Ca and Mg ions up to 150 mg L-1 showed no considerable effect on the adsorption of Ce(III). Regeneration of adsorbent was performed using HNO3 with efficiency greater than 84%. The quantities of distribution coefficient (Kd), the affinity of metal for retention onto solid phase, was the higher for Ce(III) than La(III). Due to the high sorption capacity, being plentiful and low cost it is concluded that the use of amino phosphate mofified nano titania as an appropriate adsorbent is promising for the removal of lanthanides especially Ce(III) from contaminated sites.
Full article
Reaction Engineering, Kinetics and Catalysts,
M. Basiri; M. Rahimi; H. Babaei Mohammadi
Volume 13, Issue 2 , Spring 2016, Pages 22-32
Abstract
The ultrasound-assisted (UA) soybean oil methanolysis using KOH as a catalyst was studied at different reaction conditions in a microreactor. Box–Behnken experimental design, with three variables, was performed and the effects of three reaction variables i.e. reaction temperature, catalyst concentration ...
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The ultrasound-assisted (UA) soybean oil methanolysis using KOH as a catalyst was studied at different reaction conditions in a microreactor. Box–Behnken experimental design, with three variables, was performed and the effects of three reaction variables i.e. reaction temperature, catalyst concentration and the methanol-to-oil molar ratio on fatty acid methyl ester (FAME) yield were evaluated by method of analysis of variance (ANOVA) and multiple regression. A quadratic polynomial model was obtained to predict the methyl ester yield. A yield of 97.1% for methyl ester was obtained at the deduced optimal conditions: reaction temperature of 47 °C, KOH catalyst concentration of 1.29% (w/w) and methanol-to-oil molar ratio of 6:1. Validation experiments confirmed the validity of the predicted model. At the optimal operation condition for the ultrasonic process, a higher yield of methyl esters was obtained in comparison with that of the non-ultrasonic layout. The results show that UA transesterification in microreactor minimizes the reaction time and temperature, alcohol-to-oil molar ratio as well as energy consumption.
Full article
Energy
A. Mirahmad; S.M. Sadrameli; A. Jamekhorshid
Volume 13, Issue 2 , Spring 2016, Pages 33-45
Abstract
Abstract Energy crisis is a major challenge in the current world. Latent heat thermal energy storage (LHTES) systems are known as equipment with promising performance by which thermal energy can be recovered. In the present study a comprehensive theoretical and experimental investigation is performed ...
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Abstract Energy crisis is a major challenge in the current world. Latent heat thermal energy storage (LHTES) systems are known as equipment with promising performance by which thermal energy can be recovered. In the present study a comprehensive theoretical and experimental investigation is performed on a LHTES system containing PEG1000 as phase change material (PCM). Discussed topics can be categorized in three parts. At first, a one dimensional mathematical model is introduced for a heat exchanger containing flat slabs of PCM. To consider the latent heat of phase change, effective heat capacity is used in the model. Secondly, through eight experiments designed by using factorial method, effects of inlet air velocity and temperature on the outlet stream is investigated. The results proved that having a determined temperature difference between inlet air and the PCM in both hot and cold cycles can enhance the efficiency. Finally, the feasible applications of a LHTES system for controlling the temperature swing in a greenhouse is studied numerically and the results are compared with experimental values. As a result, by using this passive coolant system diurnal internal temperature can be reduced for 10 °C.
Full article
Modeling and Simulation
M. Mahmoudian; A. Ghaemi; H. Hashemabadi
Volume 13, Issue 2 , Spring 2016, Pages 46-56
Abstract
In the Bayer process, the reaction of silica in bauxite with caustic soda causes the loss of great amount of NaOH. In this research, the bound-soda losses in Bayer process solid residue (red mud) are predicted using intelligent techniques. This method, based on the application of regression and artificial ...
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In the Bayer process, the reaction of silica in bauxite with caustic soda causes the loss of great amount of NaOH. In this research, the bound-soda losses in Bayer process solid residue (red mud) are predicted using intelligent techniques. This method, based on the application of regression and artificial neural networks (AAN), has been used to predict red mud bound-soda losses in Iran Alumina Company. Multilayer perceptron (MLP), radial basis function (RBF) networks and multiple linear regressions (MLR) were applied. The results of three methodologies were compared for their predictive capabilities in terms of the correlation coefficient (R), mean square error (MSE) and the absolute average deviation (AAD) based on the experimental data set. The optimum MLP network was obtained with structure of two hidden layer including 13 and 15 neurons in each layer respectively. The results showed that the RBF model with 0.117, 5.909 and 0.82 in MSE, AAD and R, respectively, is extremely accurate in prediction as compared with MLP and MLR.
Full article
Transport Phenomena,
Sh. Ghodbanan; R. Alizadeh; S. Shafiei
Volume 13, Issue 2 , Spring 2016, Pages 57-70
Abstract
In this study a developed model has been used to evaluate the paper drying process and examine the pocket dryer conditions of a multi-cylinder fluting paper machine. The model has been developed based on the mass and energy balance relationships in which the heat of sorption and its variations with paper ...
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In this study a developed model has been used to evaluate the paper drying process and examine the pocket dryer conditions of a multi-cylinder fluting paper machine. The model has been developed based on the mass and energy balance relationships in which the heat of sorption and its variations with paper temperature and humidity changes have been taken into account. The applied model can be used to compute the drying parameters and analyze the pocket drying conditions. Furthermore, the effects of web tension on the heat transfer have been investigated. In the available operating range of the web tension, the overall mean heat transfer coefficient will be within 300-550 W/m2.K. The pocket air temperature was between 50 and 90 oC. The dew point temperature wasn’t close to the pocket air temperature and dew drop never happened during the dryer section. Based on the modeling result and using a novel technique, the maximum level for the exhaust air in the studied machine can be estimated to be 0.2 kg H2O/kg dry air. Result shows that increasing the exhaust humidity to the optimal level will lead to 4% reduction in the required energy and 20% rise in the heat recovery potential. Accordingly the specific heat consumption per evaporated water for the studied drying section can be reduced from 3.96 to 3.81 GJ per ton water.
Research note
Reaction Engineering, Kinetics and Catalysts,
B. Mokhtarani; S. Babaei; H.R. Mortaheb; K. Tabar Heidar
Volume 13, Issue 2 , Spring 2016, Pages 71-79
Abstract
Polycyclic aromatic hydrocarbons (PAH) are toxic, mutagenic, and carcinogenic compounds. Removal of these compounds has a great importance for environment. Removal of PAHs from soil is difficult as these chemicals are persistent in the soil. In this research, bioremediation of soil contaminated by (PAH) ...
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Polycyclic aromatic hydrocarbons (PAH) are toxic, mutagenic, and carcinogenic compounds. Removal of these compounds has a great importance for environment. Removal of PAHs from soil is difficult as these chemicals are persistent in the soil. In this research, bioremediation of soil contaminated by (PAH) using Bacillus subtilis DSMZ 3256 (B.subtilis) strains was studied. The effect of electrokinetic on biodegradation of PAH was investigated. Fluorene and phenanthrene were selected as PAH and were mixed with soil. The bioremediation experiment was initially performed at 30oC and different humidities. The results represented 12.2 and 11.9% removal of fluorene and phenanthrene at 40% relative humidity after 7 days, respectively. The effects of electrokinetic on this process were studied at different current densities. It was found that the electrokinetic can reduce the biodesulfurization time. According to the results, the removal percents of fluorene and phenanthrene after 4 days under current density 1.82 mA/cm2 were 39.4 and 37.2, respectively.
Full article
Reaction Engineering, Kinetics and Catalysts,
V. Rajendran; P. Abimannan
Volume 13, Issue 2 , Spring 2016, Pages 80-87
Abstract
Ultrasound assisted phase-transfer catalyzed preparation of ethyl 2-(4-nitrophenoxy)acetate from the corresponding p-nitrophenol and ethyl 2-bromoacetate using the mild solid base, anhydrous potassium carbonate, under very mild conditions is reported. The solid-liquid reactions were performed in a batch ...
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Ultrasound assisted phase-transfer catalyzed preparation of ethyl 2-(4-nitrophenoxy)acetate from the corresponding p-nitrophenol and ethyl 2-bromoacetate using the mild solid base, anhydrous potassium carbonate, under very mild conditions is reported. The solid-liquid reactions were performed in a batch reactor equipped with reflux condenser, and ultrasonic irradiations were introduced using an ultrasonic bath operating at a frequency of 28 kHz with a power rating of 300 W. The reaction was carried out at 50°C under pseudo-first order conditions and was monitored by gas chromatography (GC). From the experimental data, a rate expression had been developed to explain the kinetic behavior of the reaction from which the apparent rate constant (kapp) of the organic phase was attained. The effects of different operating parameters such as stirring rate, temperature, catalyst loading and kind of Phase-transfer catalysts, base variation and quantity of water, kind of solvents have been investigated to maximize the yield of synthesis of ethyl 2-(4-nitrophenoxy)acetate.