Biomedical and Biotechnology,
F. Amiri; A. R. Habibi; M. M. Nourouzpour
Abstract
The application of the agro-industrial waste as the feedstock helps to decrease the operational cost of the fermentation process. Soapstock is a by-product of the vegetable oil refinery and enriched with fatty acids including linoleic acid which has a high potential application in the production of biosurfactants. ...
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The application of the agro-industrial waste as the feedstock helps to decrease the operational cost of the fermentation process. Soapstock is a by-product of the vegetable oil refinery and enriched with fatty acids including linoleic acid which has a high potential application in the production of biosurfactants. In this study, a dual carbon source system, including glucose and free fatty acids recovered from a sunflower soapstock, was used for the synthesis of sophorolipid (SL) by Candida catenulata. The production of SL showed a major dependence on the initial carbon sources and the concentration of urea as the nitrogen source. The inoculum size was another influential factor in the fermentation process. The optimization of these factors was evaluated by the one-factor-at-a-time and the response surface methodology (RSM). The one-factor-at-a-time approach gained the best SL productivity (Y1) of about 52.08 mg L-1 h-1 and SL-to-biomass yield (Y2) of 712 mgSL gcell-1 at the inoculum size of 4% vv-1, 100 g L-1 of glucose, 80 g L-1 of soapstock, and 7.5 g L-1 of urea. While the RSM, due to considering interactional effects of the factors, obtained the best condition at 100 g L-1 of glucose, 100 g L-1 of the soapstock, 9.3 g L-1 of urea, and an inoculum size of 6.3% vv-1 with the Y1 and Y1 values of about 58.10 mg L-1 h-1 and 713 mgSL gcell-1, respectively. The characterization of the produced SLs by the GC-MS analysis indicated that a di-acylated C16:1 acidic sophorolipid with an m/z ratio of 679 amu was the main product.
Separation Technology,
P. Abbasi; k. Shayesteh; v. vahidfard; M. Hosseini
Abstract
In an Iranian zinc smelter plant, nickel and cadmium are removed from the electrolyte solution at the cold purification stage with the help of zinc powder. This study tries to investigate the optimal conditions for the removal of these impurities through the response surface methodology by examining ...
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In an Iranian zinc smelter plant, nickel and cadmium are removed from the electrolyte solution at the cold purification stage with the help of zinc powder. This study tries to investigate the optimal conditions for the removal of these impurities through the response surface methodology by examining the effects of effective parameters on the process. The results of the experiments showed that cadmium was cemented by zinc powder much more conveniently than nickel. The interplay of parameters showed that increasing the concentration of zinc powder can reduce the time and temperature of the entire reaction. It also neutralized the effect of the changes of pH and mixing speed. The optimum conditions for the simultaneous removal of nickel and cadmium were obtained at 75 °C, the pH of 4.5, the residence time of 45 min, the mixing speed of 500 rpm, and 2 g/l of zinc powder. Under optimal conditions, more than 99 % of nickel and cadmium were removed from the electrolyte solution.
M. Mozafari; A. Ganjizade; .S. N. Ashrafizadeh
Abstract
In this work, the demulsification of water-in-crude oil emulsions by dielectrophoresis via applying a non-uniform electric field in a lab-scale cylindrical cell was studied. The stability of emulsions was assessed through monitoring the size distribution of water droplets at 0, 3, 6, and 24 hours after ...
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In this work, the demulsification of water-in-crude oil emulsions by dielectrophoresis via applying a non-uniform electric field in a lab-scale cylindrical cell was studied. The stability of emulsions was assessed through monitoring the size distribution of water droplets at 0, 3, 6, and 24 hours after the preparation of emulsion. The effect of operating parameters including the temperature, demulsifier concentration, water salinity, and time on the demulsification of water was investigated. Sodium dodecyl sulfate and sodium chloride were used as demulsifier and salt respectively. The experiments were designed by the response surface methodology (RSM) based on the central composite design (CCD). The operating parameters including the voltage, temperature, demulsifier concentration, salinity of water, and separation time were optimized. The contours and 3-D response surfaces of the water separation were acquired. A quadratic polynomial model, which was statistically highly significant (R2=0.9950, n=32), was provided by the RSM to predict the amount of the separated water. Comparison among the experimental and RSM-optimized values indicates a good agreement. The optimum amount of the water separation was obtained at the voltage of 15 kV, temperature of 60 °C, demulsifier concentration of 123 ppm, salinity of water of 12260 ppm, and separation time of 12.4 minutes. Under such conditions, the separation of water reached 98 %. The results obviously show that the electric field can be used as an appropriate means for the breakage of W/O emulsions.
Separation Technology,
M. Yasemi; M. Rahimi; A. Heydarinasab; M. Ardjmand
Volume 15, Issue 3 , September 2018, , Pages 15-33
Abstract
In this study, extraction of tannic acid using microchannel was investigated. Affective parameters were optimized. Different solvents including buthanol, ethylacetate and n-hexane as organic phase, methanol, propanol, ethanol and water as aqueous phase investigated. Microchannels with different confluence ...
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In this study, extraction of tannic acid using microchannel was investigated. Affective parameters were optimized. Different solvents including buthanol, ethylacetate and n-hexane as organic phase, methanol, propanol, ethanol and water as aqueous phase investigated. Microchannels with different confluence angles and diameters were examined. Microchannels with different confluence angles and diameters were examined. The effects of pH, temperature, and volumetric flow ratio and contact time of the two phases were investigated. The response surface methodology was used to optimize extraction yield of tannin from Quercus leaves in the employed microchannels. Based on this optimization, maximum yield was achieved at pH=2, temperature=33.1℃, volumetric flow ratio =1.2 and contact time of 25.35s. Results show that extraction-using microchannel has many advantages over traditional methods, including shorter time and higher economic efficiency. Moreover, microchannel provides smaller volume of fluids resulting in lower solvent consumption, lower waste production, shorter analytical times, smaller space requirements, and lower energy consumption.
Reaction Engineering, Kinetics and Catalysts,
H. kalantari; M. Nosrati; S. A Shojaosadati; M. Shavandi
Volume 14, Issue 1 , March 2017, , Pages 74-87
Abstract
In the present study, the effects of four factors including initial sulfide concentration (mg l-1 ), agitation speed (rpm), amount of inoculums (%) and sodium concentration (mg l-1) on removal efficiency (%R) and yield of sulfate production by Thioalkalivibrio versutus from synthetic spent caustic were ...
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In the present study, the effects of four factors including initial sulfide concentration (mg l-1 ), agitation speed (rpm), amount of inoculums (%) and sodium concentration (mg l-1) on removal efficiency (%R) and yield of sulfate production by Thioalkalivibrio versutus from synthetic spent caustic were investigated. For this purpose, experiments are designed by design of experiments (DOE) and Response Surface Methodology uses results of experiments to determine relationship between experimental factors and measured responses. The coefficient of determination (R2) was calculated as 0.9012 and 0.9544 for removal efficiency (%R) and yield of sulfate production (Y_(SO4/S)), respectively. The best local maximum was found to be at initial sulfide concentration 1500 mg/l, agitation speed 180 rpm, inoculum 8%, Na concentration 1.38 M , removal efficiency 96.99%, yield of sulfate production 2.65 and desirability of 0.909. According to these observations and results Thioalkalivibrio versutus is a suitable bacterium for oxidation of sulfide in spent caustic wastewater.
Separation Technology,
Jafarsadegh Moghaddas; Leila Amirkhani; Hoda Jafarizadeh- Malmiri
Volume 13, Issue 3 , July 2016, , Pages 19-31
Abstract
Magnetic silica aerogel in hydrophobic and hydrophilic forms were used as support to immobilize Candida rugosa lipase by adsorption method. Response surface methodology (RSM) was employed to study the effects of the three most important immobilization parameters, namely enzyme/support ratio (0.3-0.5, ...
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Magnetic silica aerogel in hydrophobic and hydrophilic forms were used as support to immobilize Candida rugosa lipase by adsorption method. Response surface methodology (RSM) was employed to study the effects of the three most important immobilization parameters, namely enzyme/support ratio (0.3-0.5, w/w), immobilization time (60-120 min) and alcohol percentage (20-40, %v/v) on the specific activity of immobilized lipase on the hydrophobic supports. For hydrophilic supports, alcohol percentage was removed as there was no need for pre-wetting step in enzyme immobilization process. Second order regression models with high coefficient determination (R2) values of higher than 0.98 were fitted to predict the response as function of immobilization parameters. The results indicated that for hydrophobic supports, optimum values for enzyme/support ratio, immobilization time and alcohol percentage were obtained at 0.45 (w/w), 94.27 min and 38.81 %, respectively, in which specific activity were predicted at 15.32 U/mg-protein. For hydrophilic supports, the optimum enzyme/support ratio and immobilization time were predicted at 0.47 (w/w) and 83.47 min, respectively. Specific activity in these conditions were obtained 11.21 U/mg-protein. As the difference between the experimental and predicted values was showed as non-significant, the response surface models employed could be considered as adequate.
Reaction Engineering, Kinetics and Catalysts,
M. Basiri; M. Rahimi; H. Babaei Mohammadi
Volume 13, Issue 2 , April 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.