Sharif Digital Repository

In this thesis, polyethylene vinyl acetate and polyethylene shrinkable nanocomposite films with different percentages of an organoclay such as 0, 1, 3, 5 and 7% have been prepared via two-steps solution method. Morphological and properties of these films, including permeability and mechanical and rheological properties were investigated. Also the effect of addition of cross linking agent (DCP) was studied. Various tests including XRD, SEM, tensile and rheological properties were studied. XRD tests showed that the distance between a layer of or ganoclay increased to 32 percent. This indicates that the polymer chains between the layers of organoclay could be better. SEM examination showed that... 

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,... 

Due to increasing environmental concern, special interest has been paid to reduction of organosulfur compounds in transportaion fuels. The sulfur- containing compounds are converted into sulfur oxide, i.e, SOx , during combustion, which is a major source of acid rain and air pollution.Gas condensate is a mixture consisting primarily of pentanes and heavier hydrocarbons which is recovered as a liquid from natural gas. It is a proper hydrocarbon source for producing gasoline, kerosene and gas oil in refineries. In this reseach a gas condensate was used as feedstock for studing oxidative desulfurization (ODS). The influence of various parameters of desulforization including the reaction... 

Monopropellant thrusters are one of the most common types of propulsion systems that are used extensively in space applications. Especially thrusters with a capacity of less than 50N, they are used on space satellites and are developing rapidly. Problems such as contamination, toxicity of the propellant, difficulty in storing and custody, as well as price, led to the removal of the hydrazine from the focus of attention and focus on green propulsion. One of these, is the green propellant of hydrogen peroxide, which is decomposed in the proper catalytic vicinity, and the only chemical decomposition products are oxygen and water vapour. The present study aims to design and construct mono... 

Oxidative desulfurization (ODS) is one of the desulfurization processes that posseses several important advantages such as mild operating conditions. In the present work, oxidative desulfurization of kerosene with a total sulfur content of 2335 ppm and gas oil with a total sulfur content of 7990 ppm were carefully investigated. By evaluation of different oxidation systems, the hydrogen peroxide-formic acid system was selected for the oxidation of sulfur-containing compounds of the light fuel oils. The effects of main operating parameters of the oxidation system including temperature, hydrogen peroxide to sulfur molar ratio (O/S), and formic acid to sulfur molar ratio (Acid/S) on the... 

An antioxidant is a molecule capable of preventing the oxidation of other molecules and neutralizing free radicals. Free radicals are the root cause for many human diseases.Rice bran is one of the most important co-products in the rice milling.In this research antioxidant activity of two Iranian rice bran varieties Fajr and Tarem, extracted by three different solvents (methanol, ethanol and ethyl acetate),determined at different time of extraction by measurement of total phenolic content, free radical scavenging, inhabitation of linoleic acid peroxidation and reducing power. The methanolic extract of Fajr rice bran produced strong results in antioxidant activity. The amount of Total... 

In this study, we investigate the effect of adding potassium persulfate (PDS) (K2S2O8) and hydrogen peroxide (H2O2) to E.coli (as a model microorganism) photocatalytic removal system in the presence of the TiO2-P25 as photocatalyst and UV irradiation. In this regard, the PDS and H2O2 oxidants were added separately in the different levels of pH and photocatalyst loading under UV irradiation. The experimental points were determined based on the central composite design (CCD) and in order to study the main and the interactive effects of the photocatalyst concentration (mg/L), oxidant concentration (mg/L) and the pH on the final concentration of E.coli (cfu/mL), a response surface model (RSM)... 

Silver and gold are precious, expensive metals and are used in various applications, such as jewellery and ornamentals, electronics and optics. In the present study, soda-lime glass surfaces firstly were activated with acidic stannous chloride solution. Then, silver and gold were coated on these surfaces via simultaneous spraying of two solution: A silver- or gold-complex bearing solution and a reducing agent (Dextrose for Ag and H2O2 for Au) bearing solution. For silver coating, the effect of various parameters such as time, reducing agent concentration, number of passes, presence and concentration of Urotrpin and Decamethylcyclopentasiloxane (DMCPS) as microstructural modifiers and... 

External radiotherapy is a major method of treating cancer. In this method, penetrating rays such as X-rays, alpha, beta and gamma emitted from the device are used to treat cancer. In order to emitting rays only to the cancer cells, masks are used to stabilize the patient's body in the right position during the radiotherapy, so that the rays are not emitted to the healthy tissues of the patient's body. In this dissertation, first, different methods of making radiotherapy masks are examined. Next, polycaprolactone is proposed as the main material for making the mask. Due to its low tensile strength, this material alone is not suitable for the intended use. Therefore, the material was cured...