Sharif Digital Repository

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... 

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... 

The aim of this project is to achieve a semi permeable high flux membrane with a reasonable salt rejection for the treatment of low osmotic pressure water. A thin film composite membrane consists of three polymeric layers was studied in this project. These layers were polyester support, polysulfone sub layer and polyamine selective layer. The polyester support provides the mechanical resistance against the operating pressure. The polysulfone sub layer provides the suitable area for polyamide synthesize, and the polyamide layer is the selective active layer of membrane.
The resistance to water penetration in sub layer was reduced first and then, the pores in the polyamide layer refined by... 

Osmotically assisted reverse osmosis (OARO) assimilates high efficiency due to non-thermal processes and accessing high salinity. This makes it suitable for high water recovery for the purpose of zero- and minimal liquid discharge desalination. Moreover, forward osmosis (FO) has low fouling efficiency which makes the operating costs of cleaning and replacement lower. This study aims at incorporating OARO and FO in a novel configuration with multiple inlet of the diluted draw solution to the regeneration section. Pinch analysis with simplifying assumptions was carried out for FO and OARO standalone stages. The results showed that pinch point in FO resides either on the beginning or at the end... 

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.... 

Membrane fouling is the main cause of permeate flux decline and loss of product quality in reverse osmosis (RO) systems, so good pretreatment of the feed solution was required to prevent membrane fouling. One of the most common applied pretreatment methods to prevent or control the scaling of different salts in feed water is to add scale inhibitors. Due to the great variety of commercial scale inhibitors RO plant operators must evaluate these chemicals before use in real plants. In this project three different types of antiscalants at concentrations of 10 ppm and one type of magnetic descaler on the RO pilot for the R.O plant feed water of agro-industrial Hakim Farabi evaluated and function... 

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 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...