Sharif Digital Repository

Silica nanoparticles is one of the most important mineral particles. In this study, Sodium silicate, Sulfuric acid and Sodium aluminate is used in order to synthesis of the modified Silica nanoparticles. The effects of temperature, reaction time and the molar ratio of regents were tested and optimized. Synthesized nanoparticles were characterized by use of XRD, FT-IR and SEM techniques. The results show that by controlling the reaction conditions, nanoparticles with an average size of 26.2 nm is obtained. The increase of temperature and reaction time alters the structure of the particles of amorphous state to a crystalline needles. The particle surface modification process was performed by... 

Nitrate can be used as an oxidant in a cathode chamber of microbial fuel cell. Nitrate is known to be a pollutant of water particularly underground water and is considered a carcinogen of water. Nitrate was used in the cathode chamber of a microbial fuel cell as an oxidant that lead to simultaneous generation of electricity, removal of organic matter in anode, and removal of nitrate in the cathode. Using nitrate generated a voltage of 151 mV with an external resistance of 1000Ω. The maximum power density achieved was 1.375 mW/m2 with an external resistance of 800Ω. Seven days after the cell became operational and without the presence of a catalyst, the amount of COD had decreased by 25... 

ZnO nano particles and mordnite zeolite nano particles were prepared by precipitation method and hydrothermal method,respectively. The influence of solvent and surfactant in ZnO nano particles synthesis were studied to reform the structure of nano particles.These nano particles were based on different supports to improve and enhance their photocatalytic activities. Synthesized catalysts characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform-infra red spectra (FTIR), UV-Vis spectroscopy and BET techniques. To investigated photocatalytic activity of the synthesized catalysts under UV irradiation, they were used to degradation bio-environmental... 

In this work we intend toeconomically recovery of residual from terephthalic acid production unit in the Tondgooyan petrochemical company. Major component of this residual is catalysts, benzoic acid and amount of terephthalic acid product. Catalysts contains of cobalt, manganese and bromide which recycled by water extraction. Effective variable on extraction process is dilution ratio of water to residue, extraction temperature and time. Optimum condition of catalystsrecovery consist of dilution ratio of water to residue 6:1, extraction temperature and time is 45 C° and 40 minrespectively. Recovery yield of cobalt, manganese and bromide in this optimum condition is 91.21, 91.89 and 92.53... 

Natural products obtained from plant extract are well known as a valuable source for research and assessments which eventuates to the discovery of some compounds possessing biological and pharmacological properties. Our aims have been to investigate and identify some natural products having the ability to effect on protein misfolding. In neurodegenerative disorders, like Alzheimer’s and Parkinson’s, a protein or a peptide undergoes conformational changes, and consequently the protein transform to fibrils coined amyloid. To determine the effective anti-amyloid compounds in natural products, Borage leaves was chosen. The plant extract was extracted using soxhlet and applied to hen white egg... 

In the first chapter of the thesis the synthesis of indolylsulfanyl acetamide derivatives using thio-oxindoles has been reported. The properties of this reaction are, one-pot, without using catalysts, acetonitrile solvent and the raw material is available. This reaction has high yield and seperation products is done using column chromatography. Indole derivatives has various medicinal and biological properties and synthetic products in this project has indole ring, aldehyde and amide functional groups. In the second chapter of the thesis, a new magnetic nanocatalyst has been designed. The magnetic nanoparticles were coated with triazole ligand and then palladium (II) ion was loaded onto the... 

The petroleum industry is one of the technological applications which more platinum-group metals (PGM) employs. Therefore, the recovery of the PGMs from the waste catalysts of petroleum industry could be an important source to obtain these precious metals, with economic and environmental consequences.
In this work, the recovery of platinum and palladium from petroleum catalysts has been studied using waste RG-582 and LD-265 catalysts. Both catalyst were characterized through XRF, XRD and AAS. Aqua regia used as a leaching agent and The effect of dissolution temperature and time, liquid/ solid ratio (L/S), size of particles and elimination of coke was investigated. Under optimized... 

The topic of influencing and regulating the behavior of communities is one which has always gathered attention by various governments, civic institutions, organizations and individuals. Research in this topic has recently been accelerated with the expansion of large scale online social networks. The massive moment of user data which exists in such settings has led to various researchers investigating methods to create new social behaviors such as habits, values and norms, with the core of these methods being the flow of ideas between social actors in order to create such social habits and behaviors.In this context, social norms are a core concept in social sciences and play a critical role... 

Nowadays, the study of flow and heat transfer in turbine engines has become critical due to their increasing use and importance in various engineering industries. The critical issue of blade burning in the first row of turbine’s blades illuminates the critical roles of numerical and experimental activities in reducing these undesirable effects. Since blade cooling is directly related to the secondary air system, one important issue in blade burning research is to utilize the conjugate heat transfer approach. As Known, an increase of about 1% in the mass flow of air entering into the secondary air system would cause an increase of about 0.5% in the engine specific fuel consumption (SFC),... 

Space debris have increasing importance for space missions. The towing removal scheme is one of the most promising ways for active removal of these debris from LEO orbits. In this approach, an active propelled satellite captures the debris via a space tether and a tethered net which by producing a force opposite to its velocity, it will cause deorbiting and burning the debris in the dense atmosphere. One of the issues with this technique is the danger of tether rupture which for solving that two tethers instead of one can be used. In this research study of active removal of flexible space debris via double tethered towing system has been done. Dynamic modeling has been done with Newton’s and...