Sharif Digital Repository

Oxygen enriched combustion is one of the attractive combustion technologies to control pollution and improve combustion in diesel engines. In the present work after an introduction to membrane seperation and membrane seperators for oxygen-nitrogen from air, a simulation of combustion chamber by GT-Power and membrane COMSOL Multiphysics was used to study the impact of oxygen enrichment on combustion, pollution and performance parameters with 23, 25 and 27% levels of enrichment. Increasing the oxygen engine content with the air leads to faster burn rates and the ability to burn more fuel at the same stoichiometry. These effects have the potential to decrease specific fuel consumption and... 

One of the most popular methods in order to protect foods is to package using various materials. By this act, the shelf life of the packaged foods may range from a few days to more than a year. Multiple types of plastics are being used as materials for packaging food, including polyolefin, polyester, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, and ethylene vinyl alcohol. Although more than 30 types of plastics have been used as packaging materials, polyolefin and polyesters are the most common. Biaxially Oriented Polypropylene (BOPP) is a polypropylene film that has been stretched in both the machine and cross directions. BOPP film has become one of the most popular... 

Energy and the environment issues are among the most important concerns of the present age. Global demand for energy is growing rapidly and energy demand is projected to double in the coming years. However, today most of the energy consumption comes from fossil fuels, which have limited and unstable reserves and are among the sources of environmental pollution. Hence, the production and conversion of clean energy from renewable sources is considered as an intelligent solution to significantly reduce dependence on fossil fuels and protect the environment. Fuel cells, metal-air batteries, and water electrolysis are among the simplest, most efficient, and most reliable technologies among... 

Antibiotic medications are widely used in medicine and veterinary medicine. Since these drugs are extremely dangerous to the environment and specially to drinking water for humans and other organisms, the need to treat these wastewater is becoming increasingly important. One of the most commonly used antibiotics is oxytetracycline which is used for a wide range of infectious diseases Husbandry wastewater is one of the wastewaters that contains high diversity and large amounts of antibiotics. In this study, the performance of a Moving bed biofilm reactor (MBBR) was investigated for removal of oxytetracycline from synthetic wastewater with similar characteristics to Husbandry wastewater. A... 

Selective oxidation of cyclohexene and styrene were investigated using molecular oxygen under mild conditions. Au/TiO2 and Au/Al2O3 surfaces were impregnated with three different Ionic Liquids. Supported Ionic Liquids gold nanocatalysts are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and significant selectivity.
Selective oxidation of alkenes by hexadecyl-trimethyl-ammonium bromide-stabilized gold nanorods and gold nanosphere were investigated using molecular oxygen in aqueous solution under mild conditions. Colloidal gold nanoparticles are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and... 

Oxygen gas has many applications and is used in respiration, welding, methanol production, steel industry, rocket fuel and most importantly fuel cells. Today, due to the environmental pollution caused by fossil fuels, the use of clean energy production methods such as fuel cells has received much attention. In hydrogen fuel cells, electrical energy is generated using oxygen and hydrogen gases through an electrochemical process. One of the common methods of producing these gases is electrolysis of water in which the kinetics of anodic reaction (oxygen evolution) have led to many researches in the field of improving metal and non - metal electrocatalysts, especially based on carbon... 

Decomposition of seawater with the help of sunlight is one of the most promising ways to produce hydrogen as a clean and acceptable fuel in the future. Tungsten photoelectrode is a suitable option for seawater decomposition due to its medium bandwidth, excellent load transfer properties, good chemical stability in acidic and neutral environments, abundance and cost-effectiveness. On the other hand, intermediate metal catalysts (Fe, Ni, Co) are very important due to their abundance in the earth's crust and their stability in alkaline and neutral environments instead of oxides of precious metals (RuO2, IrO2). In this study, tungsten plate (WO3) nanostructures were grown on the surface of a... 

The number of operating vehicles has increased in recent years and as a result global pollutants have widely spread. Therefore, the regulations on the vehicle exhaust emissions have become much stricter. For an automobile to pass the emission tests successfully an accurate calibration of the ECU tables is needed, especially the tables which have direct impact on the amount of pollutant emissions. To achieve the optimum performance of the catalyst existing in the exhaust system of the engine, the fuel/air ratio must have nearly stoichiometric value. The present research studies the ECU strategies for implementing this objective by appropriate management and control of catalyst and oxygen... 

Synthesis, characterization and photoelectrocatalytic performance evaluation of worm-like BiVO4 porous films have been conducted in this research. An in situ combustion approach was employed to prepare BiVO4 nanolayers on glass and ITO/glass by using drop casting, spin coating, dip coating and pulsed spray pyrolysis deposition techniques. The precursor solution of vanadium and bismuth include ~0.0233g ammonium metavanadate (NH4VO3) and ~0.0970g bismuth (III) nitrate pentahydrate (Bi(NO3)3.5H2O) in 2.5 mL ethylene glycol. Different deposition parameters were investigated for each of the aforementioned deposition techniques to obtain a uniformly-deposited BiVO4 nanolayer with high adhesion to... 

TiO2 is known as a photocatalyst in near UV-Visible light region with better efficiency compared to other semiconductor photocatalysts. Many attempts have been done to increase the efficiency of this photocatalyst. also, application of 2D carbon nanostructures namely graphene for increasing the photocatalytic activity of TiO2 has shown positive results.
In this research, we first synthesized Graphene Oxide (GO) suspension by exfolation of graphite oxide suspension. then we fabricated TiO2 thin films on glass substrates by so-called sol-gel method. finally we fabricate Graphene Oxide/TiO2 nanowalls composite films as a photocatalyst in visible light. X-ray photoelectron spectroscopy... 

hydrogen considered as one of clean energy carriers and is the most promising alternative to fossil fuels. The production of hydrogen from photoelectrochemical water splitting using titanium dioxide nanotubes arrays (TNA) as a photoanode has been of interest to many researchers in recent years. In this study, TNAs were fabricated with two-step anodic oxidation method at a constant applied voltage of 60 V DC. The fabrication process was performed for duration time of 1, 2, 3, 4 and 5 hours. Photoelectrochemical analysis for the fabricated samples shows that TNA prepared for 3 hours anodic oxidation time exhibited the highest current density of 1 mA.cm-2 at 0.5 V bias voltage (Optimized... 

Oil refineries, petrochemical factories and oil platforms produce a large amount of oily wastewater every day. If these wastewaters are released in environment, it can damage soil and water seriously. Although, Biological treatment of oily wastewaters is a well-established method for remediation of these wastes, efficiency of conventional systems such as Activated Sludge, aren’t very high. Also these systems have many problems such as instability during hydraulics shocks and bulking phenomena. the hybrid bioreactor system are designed to increase the efficiency of treatment by allowing greater organic loads, increasing microbial concentration by using attached and suspended bacteria, and... 

For improving cost competitiveness of both SOEC and SOFC technology, it is desirable to reduce the temperature of operation preferably down towards 500 oC – 600 oC, as this will slow down the rate of various degradation processes and allow use of much cheaper materials for auxiliary components. In this range, the oxygen electrode typically dominates the cell resistance, and hence there is a need to develop cost effective electrodes with improved performance at low temperature. Whereas the oxygen exchange on Ruddlesden-Popper type Ni based compounds like Pr2NiO4 with interstitial oxygen defects is known to be very fast, reported electrode performance of micron-sized composites based on these... 

In this study, polyethylene films made of LDPE / LLPE / reinforced with mechanical barrier of clay and reactant of iron nanoparticles were made in their optimal combination and necessary improvements were made on them. Investigations show that, independent of volume fraction, the addition of spherical nanoparticles does not have much effect on reducing the polymer matrix’s permeability. In nanocomposites containing cylindrical particles, for considerable reduction of the permeability, over 20 volume percent of nanoparticles it is required, while in platelet nanoparticles, less than 10% vol is sufficient. In clays with modifier concentration above the cation exchange capacity, there is less... 

In the first part of this thesis, the application of core-shell magnetic nanoparticles supported V(V), Mo(VI) and Mn(III) complexes in the catalytic oxidation and reduction reactions was discussed. A magnetically recyclable vanadium(V) catalyst was synthesized by covalent anchoring of VO(salen)Cl on silica coated Fe3O4 nanoparticles. These nanoparticles were efficient catalysts for selective oxidation of sulfides to corresponding sulfoxides with urea hydrogen peroxide in excellent yields. Leaching and recycling experiments revealed that the nanocatalyst can be applied for nearly complete oxidation of sulfides for at least five successive cycles. A manganese(III) complex was immobilized on... 

In this project, cellulose acetate butyrate (CAB) nanofibrous membranes in order to separate the contaminants of an industrial wastewater were prepared. Electrospinning process that is an effective method to fabricate nanofibers was used to prepare the membranes. Since various parameters affect this process and fibers morphology, optimization of these parameters is necessary for preparation of improved membranes. So the effect of parameters of solvent system, polymer concentration, applied voltage, distance between the tip of needle and collector, and rotational speed of collector on morphology and diameter of the nanofibers was investigated. Scanning electron microscopy (SEM) and image... 

Nowadays with the increasing population of the world and constraint or even water shortages, necessity of reuse the effluent of the treatment plants is further increased whearas the grey wastewater (wastewater related to bathroom, dishwasher and laundry). They are part of the household wastewater.quantity ranging from 65% to 75% sewage produced in the house is grey water. In many developed countries of the world the grey wastewater treatment and its use in non-potable wastewater like irrigation, car washing and toilet siphoning are commonplace. This wastewater is lower in COD and BOD than conventional wastewater but it still needs to be refined. There are varios methods including biological... 

In this project, function of anaerobic digestion of organic waste in liquid phase and treating the following sewage in biologic tower(trickling filter) has been investigated in an experimental process. Solid waste were supplied from sharif university restaurant and after weighting and classification is added to tanks which filled by 40% sludge and 60% water. For controlling the function of biologic tower, a control reactor were used. Retention time for digestion of solid waste is 40 day. First solid loading was 500g and 75g organic waste in main & control reactor equal to 5(kg solid waste)/( m^3.reactor.day) 1.3(kg TS)/( m^3.reactor.day) and were doubled in second loading. It seems that... 

Nowadays with the extension of industry and factories as well as different kinds of plants, a wide range of pollution and circumference hazardous has been entered to the people`s life. Industrial wastewater has been always a threat for health of our environment and efforts for reducing its dangerous effects are still under studies. Dairy wastewater is one of the main branches of food industrial pollutions and it has been studied in this specific project. The goal was to reduce the Chemical Oxygen Demands (COD) of dairy wastewater with oxidation of Titanium Dioxide Nanophotocatalyst oxidation under UV irradiation. Among the various methods for synthesizing of this Nanophotocatalyst, the...