Sharif Digital Repository

The purpose of the present project is to construct and improve the quality of an absorbable membrane using a supercritical process and study the effects of the operative parameters. Today, usage of biodegradable polymers is intensively increasing and these kinds of polymers are used as drug delivery carrier and tissue engineering medium. A biodegradable membrane is suitable for this goal. In this study Poly Ethylene Glycol (PEG) is used as the biodegradable polymer. Gas anti-solvent (GAS) method was applied for the production of the membrane. The used anti-solvent was Supercritical Carbon Dioxide. In order to study the effects of the operative parameters on the structure of the produced... 

In the presence project by using of hydrophilic polymer, Cellulose acetate (CA), we tried to modify the membrane made of Polyvinylidine fluoride (PVDF). The membranes were made by phase inversion method. In five levels, at least 10% and at most 30%, CA was added to casting solution. The hydrophilicity of membranes’ surface and pore size was increased. The permeation of the neat membrane of PVDF was less than 10 , on the other hand the permeation of the membranes, which were made by adding CA, was increased up to 500 . The increment of CA more than 20% reduced the porosity of membrane. In the next step to reduce the irreversibility fouling tried to reduce the pore size by adding some... 

In this study the main goal is to prepare a membrane to perform delayed drug release and absorbtion in the human body. To do so the supercritical method was used. A well-known biodegradable polymer was used. These kinds of polymers are used in drug delivery, wound dressing or scaffolding for cell culture. A membrane produced out of these kin of polymers is expected to have a good accordance with the goals.Ploy Vinyl alcohol, having very good bio degradable characteristics was used as the main polymer and Poly Ethylene Glycol (PEG) was used as an additive to make changes in the membrane structure. Also Dimethyl Sulfoxide, a polar solvent having the capability of solving both polymers is used.... 

In recent years membrane bioreactors (MBR) were widely used as an advanced process for industrial wastewater treatment. But fouling issue causes some restrictions in these systems. So for fouling reduction many researches were done.In this study for fouling improvement, blending of hydrophilic polymer (PAN) with main polymer PVDF was used. Blending membrane in phase inversion process with DMAC as solvent and water as non-solvent was made. For pore-forming in membranes, PVP as hydrophilic additive with three different composition was added and then for more enhancement of antifouling property of membrane, TiO2 nanoparticles with four different composition were added to polymeric... 

Isopropanol purifying denotes dehydration of it to utilize in industries become important these days. Conventional process like distillation could not produce this product in high purity. Using membrane-based process, pervaporation, to dehydrate Isopropanol and other organic compound has been noticed in the last years. Among all type of membranes to dehydrate alcohols, poly (vinyl alcohol) is more effective due to its high hydrophilic characteristic. But it swallows in aqueous solutions and decrease its selectivity. To enhance structural and separation properties Chitosan, TiO2 and glurataldehyde added to polymeric membranes. Nine membranes have been made in this study that can be grouped in... 

Reusing valuable materials such as water is one of the ways to achieve sustainable development. Membrane bioreactor technology (MBR) is one of the ways to reuse water and this is an alternative to another way to upgrade existing refinery.Structure and porosity of the membranes used in MBR Systems, porosity distribution, Hydrophilic or hydrophobicity of the membrane and surface roughness are very important Parameters that impact the ultimate performance of membrane bioreactor. Hence, this project focuses on optimization membrane structure to purification a specific type of wastewater. So amount of polymer and nanoparticle membrane for MBR systems should determined by experiment design.In this... 

In this study, the performance of Convectional activated sludge reactor (CAS), moving bed biofilm reactor (MBBR) and coupled MBBR-membrane bioreactor (MBR) for diesel removal was investigated.
Hydrocarbon quantification was conducted based on a photometery method at 250 nm after extraction with n-hexane.
Experiments with MBBR was conducted in a batch mode using the sludge obtained from a municipal wastewater treatment plant. In order to adapt microorganisms with diesel as carbon sourse, diesel concentration was gradualy increased from 100 to 3400 ppm where diesel removal efficiency decreased from 62/1 to 26/6 %. However, after addition of diesel degrading bacteria (previously... 

In this work, sulfonated polycarbonate (SPC ) membranes with different acid contents have been prepared by conducting sulfonation reaction at room temperature using Chlorosulfonic acid (CSA) as sulfonating agent at different concentration of acid in reacting solution. The SPC membranes were obtained by casting from 10% solution of SPC in chloroform at room temperature. The prepared membranes were characterized using Ion exchange capacity (IEC), and degree of sulfonation (DS), Fourier Transform Infrared (FTIR), NMR spectra, Thermal Gravimetric Analysis (TGA) and Water uptake. The obtained results showed that with increaseing in Chlorosulfonic acid content in sulfonation reaction IEC and DS of... 

Supported Ionic Liquid Membranes (SILMs) are fabricated by saturating the pores of a porous support with ionic liquids. To assess the performance of SILMS, it is necessary to obtain data about the properties of ionic liquids such as diffusivity, solubility, and etc. To accomplish this task, in this project the permeability and diffusivity of CO2 and CH4 through three immidazolium-based ionic liquids: [bmim][PF6], [hmim][Tf2N], and "1-methyl-3-(3- tri methoxi silil propyl) imidazolium bis (tri fluoro methyl solphonyl)" , in the temperature range between 27-45 ℃ and pressures within 10-50 kPa, are measured. It is shown in data validation section that the results of this study are in good... 

Today, energy crises and the environmental pollution have become serious problems for the human being. To address these problems, extensive efforts have been made to replace fossil fuels with other clean energy resources such as fuel cells. In the meantime, polymer electrolyte fuel cells are very important as they are now commonly used in the field of transportation, and their importance become even more obvious as we consider the fact that the by-products from electricity production by such cells are simply water and heat. This research studies the efficiency of the polymer called “polysulfone” as an electrolyte fuel cell, which has the above named mechanical thermal and chemical... 

Off-gas flows in refineries normally consist of hydrogen, methane and heavy hydrocarbons which are burnt in flare. While the demand for hydrogen in refineries is increased and the required hydrogen is provided by steam reforming or partial oxidation of methane or other hydrocarbons, recovering the hydrogen from off-gasses can reduce the refineries losses and optimize it economically. The four main processes for hydrogen recovery unit are the Pressure Swing Adsorption process, Membrane process, Cryogenic process, and absorption process. In the present project besides, considering the process flexibility, reliability, and refinery off-gas properties such as pressure, temperature and mole... 

Microalgae is a major problem in water resources due to its adverse influence on water treatment process and water quality like color, odor and taste. In addition microalgae removal is an important process in food and pharmacy industry. Electrocoagulation is a potential method for microalgae removal. Another method for microalgae recovery is membrane treatment. This study is focusing on using both methods separately and simultaneously. To achieve this, the removal of Chlorella Vulgaris, a fresh water microalgae, was used in experiments. In first phase the experiments were solely on electrocoagulation and the effect of several parameters including current density, electrocoagulation duration,... 

Nowadays, water desalination is a widely-used method for producing clean and fresh water. Recent researches in this area have mostly focused on Reverse Osmosis technology which is one of the most efficient technologies in water desalination. A new idea to increase the efficiency of a recently-designed reverse osmosis membrane called “Honeycomb Carbon Nanotube Membrane” is presented through molecular dynamics simulation. Although in this study only the inlet area of the honeycomb structure which is a Y-shaped entrance, is modeled and studied, but obviously, any improvement in the membrane inlet, equals better results at outlet which means a more efficient desalination process. Present thesis... 

In order to increase the life-cycle of membrane filtration systems, energy efficient membranes are being developed in membrane bioreactor systems. Technology has been introduced which allows the power required to aerate the membrane for cleaning to be reduced whilst still maintaining a high flux level. Mechanical cleaning processes have also been adopted using granulates as an alternative to conventional forms of cleaning; this reduces energy consumption and also reduces the area required for filtration tanks.Membrane properties have also been enhanced to reduce fouling tendencies by modifying surface properties. This can be noted in the biotechnology industry where membrane surfaces have... 

In this research, modification of polysolfune ultrafiltration membranes is investigated. The enhancement is done via grafting of the acrylic acid as a hydrophilic monomer on the membrane surface. This is a free radical grafting method in which free radicals are formed via redox reaction of ammonium persulfate and sodium metabisulfite as an initiator. Water contact angle, molecular weight cut-off, pure water flux and fouling experiments were used to figure out the optimum conditions for the membrane performance. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were utilized to determine morphological changes of the membrane surface. Furthermore, Fourier... 

Petrochemicals, refineries and power plants are among the biggest water-consuming industries. Of all systems in mentioned complex, most water is consumed in the cooling tower system, of which the feed water of the cooling tower accounts for the largest portion of water demand. Drainage loss (blowdown) which constitutes the biggest portion of the feed water losses, varies greatly with changes in source water quality and cooling water treatment. Scarcity of water, large quantities of cooling tower blowdown water and increasing of water price lead to activities for blowdown water treatment to reuse. In this project two pre-treatment methods and two final membrane treatment methods were... 

The aim of the current project is preparation, characterization and microfiltration evaluation of nanofiberous membrane. In order to prepare membranes, the electrospinning method was utilized and polyacrylonitrile and N-N, dimethylformamide (DMF) were used as the polymer and the solvent, respectively. As the nanofiber diameter controls the structure of the membrane and also bead formation reduces the membrane uniformity, at first the effects of four most influential electrospinning parameters, such as solution concentration, applied voltage, floe rate, and the distance between needle tip and the collector, on average fiber diameter and bead area density were investigated via response surface... 

Reverse osmosis (RO) is by far the most widely used membrane desalination process worldwide. The RO process depends on the properties of semi-permeable membranes which allow the separation of water from a salt solution by applying external pressure higher than the osmotic pressure on the seawater. The main problem in membrane separation process is the fouling of the membrane walls, which decreases the permeate flux. Having spacer filaments in the feed channel has been proven to dynamically change the concentration boundary layer and preventing fouling. The impact of spacer configurations (cavity, zigzag and submerged) on the alleviation of concentration polarization and the enhancement of... 

The gas separation properties of polycarbonate (PC) membranes were investigated in this study. These membranes were prepared via dry and dry-wet phase inversion technique. Pure O2, N2, and CO2 gases were permeated through prepared membranes. The effects of membrane preparation conditions, including solvent type, non-solvent type, non-solvent/solvent volumetric ratio, polymer weight fraction, and drying temperature on the gas separation properties of dry PC membranes were investigated using Taguchi experimental design. Taguchi analysis show that polymer weight fraction offers the most important effect on the separation characteristics of the dry PC membranes. To get the highest... 

Milk is One of the most important source s of protein in the world. during the process of cheese the most of these protein remain in whey. There are different methods to separate these protein from whey. The one of advanced method is ultrafiltartion, this method is based on a permeable membranes, with different pore size. There are many research works in this field. In this project we have tried to study the effect ofpressure, temperature, concentration and resistance time on membrane porosity. In order to design the experiment and analyze the results tagochi L 16 methods is used. The PVC membranes were prepaid by gas anti solvent method, experiment showed that changes of temperature and...