Sharif Digital Repository

In this research performance of microbial fuel cells (MFCs) in continuous flow mode was studied. Different anodic chambers were tested and it was found that granular activated carbons (GACs) produced the highest power density (1228 mW/m3) in comparison with multiple anodes (731 mW/m3), single anode (294 mW/m3) and polymeric packings (40 mW/m3). It was also shown that in a plug-anodic chamber (PAC) the power output is reduced by reducing agitation of anodic volume. Adding more GACs to anodic chamber results in power increase, however by increasing occupied volume from 80% to 100% the power increase was negligible in result of cathodic reactions limitations. Feed flowrate was increased from... 

In this research, carbon nanotubes (CNTs) and CNT coated by titanium dioxide (TiO2) were used as adsorbents for desulfurization. Photocatalytic oxidation by titanium dioxide Degussa P-25 nanoparticles (as photocatalyst) immobilized on a porous and low-density support called “perlite” and CNT/TiO2 was perused. TiO2-coatings were prepared by liquid phase deposition method.This is a wet process for the formation of metal oxide thin films on substrates. The coating of nanotubes with TiO2 was confirmed by IR and EDAX and morphological properties were observed by SEM analysis.The physical properties of adsorbents were determine using BET.Dibenzothiophene (DBT)dissolved in acetonitrile was used as... 

In recent year's acrylamide as a suspected substance for tumor growth has been studied. In some researches this topic is mentioned that acrylamide is produced by the reaction of asparagine and natural sugars. This reaction takes place only at very high temperatures during the heating process. The maximum amount of this substance is determined in fried potato products. The purpose of this study was determined to remove and reduce acrylamide formation during frying of potato. Acrylamide production when it was blanching and when it was dipped in the enzyme solution of asparaginase was examined. When potato pieces were placed in a commercial enzyme solution 200 lU/ml, acrylamide formation was... 

Photocatalytic degradation is one of the developing modern and effective methods for decontamination of hazardous pollutants of chemical industrial wastewater. This method has several advantages including the possibility of using free and sustainable energy of sun. However, it is still needed to active photocatalysts under solar light and also the enhancement and optimization of operating parameters, and consequently, these topics are selected as goals of the present thesis. Accordingly in this research, first, to obtain a photocatalyst that is highly efficient (especially under visible and solar light), multi-doping and polyethylene glycol (PEG) were used and for the first time,... 

In this study, Pseudomonas aeruginosa BBRC-10036 was used for lipase production. The organism secreted the enzyme extracellulary. First of all, effect of initial pH of the culture broth on lipase activity was studied in order to determine the optimum condition for lipase production. After production, this enzyme must be separated from culture and after that the enzyme must be purified for using in analysis and industry. Different methods are used for purification of the enzyme. In this research, first precipitation was used and then this lipase has been purified by Ion exchange Chromatography leading to 2.33- fold purification and 11.47% recovery. In precipitation by acetone, maximum... 

Xanthan gum is a water-soluble exo-polysaccharide. It is produced industrially from carbon sources by fermentation using the gram-negative bacterium Xanthomonas campestris. There have been various attempts to produce xanthan gum by fermentation method using bacteria and yeast by using various cheap raw materials. In this study the cultural conditions for xanthan gum production by Xanthomonas campestris were investigated and optimized by response surface methodology, to maximize cell and xanthan production in batch experiments using YM broth without pH control. The individual and interactive effects of three independent variables (carbon source concentration (40-80 g/l), nitrogen source... 

β-galactosidase enzyme is immobilized from Kluyveromyces lactis by Microencapsulation method in various compositions of sodium alginate and Carboxymethyl cellulose. Optimum stabilization was gained at 1.85% sodium alginate, 0.9% carboxymethyl cellulose and 2% calcium chloride through applying Surface response methodology. Yield of immobilization and activity was 54.94% and 65.27%. variation of yield of immobilization versus alginate concentration was a quadratic curve with the maximum. When alginate's concentrations is low, the cavities diameter is great, so the enzyme leaks from capsule while immobilizing. At high concentrations of alginate, despite the smaller cavities, immobilization... 

Penicillin G Acylase is the key enzyme in producing semi-synthetic antibiotics such as Ampicillin and Amoxicillin. In this study, we used E.coli ATCC 11105 in order to produce it. This enzyme was an intracellular one which was produced under suitable conditions. Crude enzyme was released after cell disruption by ultrasonic waves (sonication method) and was partially purified by ammonium sulphate precipitation. Immobilization is investigated at different pHs around the iso-electric pH of Penicillin G Asylase enzyme. Therefore, optimum pH and optimum concentration of ammonium sulphate cuts were determined. Also immobilization process of this enzyme was studied on chitosan polymer, activated by... 

In this project we focused on Ultrasonic waves as novel, effective and well-controllable means for cell wall disruption and disintegration to provide faster and more complete penetration of solvent into cellular materials and improve sugar mass transfer and extraction from sugarcane and sugar beet. Impact of frequency, temperature, power density and reactor shape on Ultrasonic wave efficiency in extraction process has been investigated and the result was utilized to design a semi-pilot reactor. In the optimum situation, sucrose extraction from sugarcane improved to 4.51 gr/100 ml H2O that had a significant increasing from 2.1 gr/100 ml H2O extraction in thermal only process at 70 °C. Optimum...