Sharif Digital Repository

In this research, we focus on reduction of solutes in left out water from reverse osmosis membranous units (brine) with reduction of scaling factors of membrane. This research is important from that perspective that the out put brine from reverse osmosis membranous unit After purification by this method, enter into membranous system in order to increase in recovered water volume and also minimization of out put waste from membranous system and decrease the environmental damages. The method used in this research, is three processes of cooling, chemical desalination and seeding by crystal material. In this research is investigated the type and amount of matter for chemical desalination and... 

Surface modification of thin-film composite (TFC) polyamide reverse osmosis membrane was carried out using CO2-laser irradiation and Dielectric barrier discharge (DBD) plasma to improve performance and antifouling properties of the prepared RO membranes. Firstly, TFC polyamide RO membranes were synthesized via interfacial polymerization of trimesoyl chloride (TMC) and m-phenylenediamine (MPD) monomers over porous polysulfone ultrafiltration support. Next, CO2-laser irradiation with 10,000-40,000 pulses and DBD plasma with 15, 30, 60 and 90 seconds duration were used for the surface modification. The surface properties were characterized by ATR-FTIR, SEM, AFM, and contact angle measurements.... 

In this study the main goal is preparing an appropriate UltraFiltration membrane from PolyVinyl Chloride for using as substrate in producing efficient Reverse Osmosis membranes to use in sea water desalination. each membrane should have some specifications to use it as reverse osmosis membrane’s substrate. One of the most important specifications is the appropriate pore sizes. To investigate this subject pure water flux and PolyEthylene glycol rejection of prepared membranes is tested. After investigation of this parameters and proving them, RO membranes are prepared using this membranes.
Salt rejection of Brackish water (2000ppm) and sea water (Persian gulf,32000ppm) are measured in... 

This research aims to construct a membrane using supercritical system which can be used in the process of brackish water filtration.
For this purpose solutions of polysulfone with desired concentrations were prepared and set to be stretched on glass or nonwoven polyester with adjustable thickness. Then the film of solution was transferred into supercritical cell. Carbon dioxide was used as anti-solvent and it causes super saturation in solution.
In order to investigate the effect of operating parameters on membrane structure, pore size and porosity were considered as a symbol of membrane structure. These parameters include cell pressure and polysulfone concentration.
Generally,... 

Reverse osmosis membrane one of the common methods used for water desalination, today membrane, thin film composite(TFC) include three layers, top the these layers named selection layer, this poly amid layer contacted with feed water, sensitivity to chlorine in polyamide layer lead to high membrane chlorine sensitive. Difference methods used for enhance the chlorine resistance in polyamide membrane that categorized in three general categories, covering and protection of sensitive areas method has best results in comparison to other methods. In this research protection method choose and used, material that used, sanitized by result from surface analysis of commercial membrane manufactured in... 

In this project, modification of reverse osmosis membrane was investigated in order to reduce the biofouling in treatment of brackish water. Furthermore, the technique which is used to attain the favorable results is graft polymerization to modify the membrane’s surface with grafting acrylic acid as hydrophilic monomer onto polyamide exploited as last layer in reverse osmosis membrane. This technique is a free radical grafting, andfree radicals which are needed for grafting are provided by the redox system potassium persulfate-sodium metabisulfite which was used as initiator. To figure out the best concentration of acrylic acid, initiator and process time in order to achieve a new membrane... 

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... 

Today reverse osmosis (RO) is the dominant technology for desalination. Most of commercially available RO membranes are polyamide thin film composite (TFC) types which exhibit good performance. However, the major obstacle for application of polyamide TFC RO membranes is fouling which can be mitigate by surface modification.In this research, surface modification of fabricated aromatic polyamide TFC RO membranes was carried out using UV-initiated graft polymerization at different irradiation times (15, 30, 60, and 90 s) and various acrylamide concentrations (10, 20, and 30 g/L). Also, coating of membranes surface with various concentrations of TiO2 nanoparticles (10, 20, 30, and 50 ppm)... 

Nowadays, water and energy shortage is the main concern of many industries. Every saving that could be done is valuable. In the first step of this project, energy recovery devices that are used in reverse osmosis systems, are reviewed and advantages and disadvantages of each system are investigated. These apparatuses save energy by recovering high-pressure energy from leaving brine and reduce the energy consumption of the device. The main focus of this study is energy consumption of the device that is used for desalination of seawater in reverse osmosis systems and on this basis, different energy recovery devices are compared. According to the investigation, results showed that most of the... 

The separation ofacetic acids in binary water solutions hasbeenstudied using a reverse osmosis (RO) membrane. Thin film composite polyamide membrane is used in this study.Thin-film composite (TFC) membrane was prepared through the interfacial polymerization between m-phenylenediamine (MPD) and trimesoyl chloride (TMC) on the polysulphone support membrane.The solute permeation was carried out under applied pressure of 5 bar at 25°C. In this work the effect of various synthesis conditions on the membrane performance was investigated. Parametric studies were conducted by varyingconcentration of reactants, reaction time, curing time and curing temperature. By suitable combination of these... 

Current research studies the effect of electromagnetic field on reducing precipitation on membrane surface in reverse osmosis. Reverse osmosis is one of the most widely applied methods for water desalinization. Despite its advantages over other desalinization techniques, suffers from shortcomings such as blockage of membrane surface. Use of magnetic fields for reducing precipitation in process equipment, the so-called magnetic treatment, has been studied and practiced for decades. This research intends to study the effect of electromagnetic field on water and its mineral content, and the possibility of its application as a method for reducing precipitation and blockage in reverse osmosis... 

The purpose of this project is to correct the surface defects of the reverse osmosis membrane. The membrane tested in this project was a thin film made of three layers of polyester, polysulfone and polyamide. These three layers provide mechanical resistance to operating pressure, suitable substrate for polyamide layer synthesis and membrane selectivity, respectively.In order to improve the surface properties and modify the reverse osmosis membrane, it was first attempted to coat it with a protective layer of polyvinyl alcohol, then by modifying this layer and improving the properties of polyvinyl alcohol and synthesizing the sulfite agent on it by the esterification reaction, to the best... 

Isfahan Zirconium Production Plant (ZPP) is one of the most important plants in the nuclear industry of Islamic Republic of Iran. The wastewater of this plant contains high values of Sodium, Chloride, Nitrate and low values of Calcium, Magnesium, Zinc and Zirconium ions. Its release has been banned by international and national law because of the dangers and toxicity of its ions for the environment and living organisms. Therefore, its refinement as a compensation of Iran’s water resources in agriculture and drinking water has received a major consideration. Among the common methods to removal of these ions, membrane process method is selected due to it's major benefits such as not producing... 

The current work studies the economic investigation of reverse osmosis (RO) desalination unit and multi-effect distillation (MED) considering the average global and also Iran circumstances. Technical and operational parameters are taken into account for economic modeling of both methods to choose the proper and economic method for water desalination based on different operational conditions. The cost of the desalination plants is investigated in two different parts of capital cost and operating and maintenance cost. Capital cost is divided into direct and indirect cost subsections. Based on these calcifications, the effect of economic parameters on change of capital cost and operating and... 

Reverse osmosis membranes are one of the most common methods of desalination of water in the world today. In the meantime, aromatic polyamide thin-film composite reverse osmosis membranes have one of the best performances and can be widely used in industry. This project aims to make surface modifications on the made raw membranes and increase the degree of crosslinking to improve the functional properties of the membrane, such as the percentage of salt rejection and the flux of permeate, and the reduction of fouling. For this purpose, polyvinyl alcohol and l-arginine along with maleic anhydride as the crosslinking agent and hexamethylene diisocyanate were used for surface modification of the... 

Water is the most essential human need and the lack of fresh water soon is one of the biggest problems of mankind. One way to deal with the lack of fresh water is desalination of seawater. Seawater desalination is done by different thermal and membrane methods. In this research, the methods and history of freshwater supply methods and the role of chains in the progress of seawater desalination, and the measures taken in the field of seawater desalination have been investigated. Among the various methods discussed and proposed in this research, it was concluded that reverse osmosis membrane is available and has an acceptable economic efficiency compared to other methods. After choosing the... 

The world's freshwater resources are rapidly decreasing due to population growth, industrial and technological progress, successive droughts, climate changes, increased food demand, and poor management of water resources. Using desalination methods is one of the ways to produce the required freshwater. Several methods have been developed for desalination. The most widely used method is reverse osmosis (RO). In this thesis, an electrodialysis (ED) desalination system was designed and modeled using up-to-date and reliable articles. This modeling was done in EES software and after validating that, the effect of considering Donnan's potential was investigated. At the 60 ppt concentration of the... 

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... 

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... 

The use of superhydrophobic surfaces is one the most promising methods for reducing the friction and increasing the flow rate in fluid transfer systems. Since in such systems the surface structure plays a key role, in the first part of this study, the performance of the hierarchical nanostructures is explored. These nanostructures are inspired by the superhydrophobic surface of the lotus leaf. The flow is considered between two walls with hierarchical nanostructures and simulate the system via the molecular dynamics (MD) method. The size of the nanostructures and the distance between them have been studied to find whether a design with maximum flow rate exists. The nanostructures have two...