Preparation and Characterization of Chlorine Resistant Thin Film Composite Polyamide Membranes via the Adsorption of Various Hydrophilic Polymers onto Membrane Surfaces

다국어 초록 (Multilingual Abstract)

The surfaces of the reverse osmosis (RO) membranes prepared by an interfacial polymerization methodon the polysulfone supports in our lab were modified by the adsorption of the three hydrophilic polymers, poly(vinylsulfonic acid) (PVSA), poly(ethylenimine) (PEI) and poly(vinyl alcohol) (PVA). Using the ‘salting-out effect’, thesepolymers, representative of anionic, cationic and neutral polymers, respectively, were used to investigate whichadsorbed polymer is the most resistant to chlorine attack. The surface properties of the adsorbed RO membraneswere characterized to confirm the adsorption by using contact angle measurement and scanning electron microscopy(SEM). The performance of chlorine-resistance RO membranes was measured through their evolution, before andafter hypochlorite exposures in 3,450 ppm NaOCl solution for desired time points. This was determined in terms ofpure water permeability and salt rejection. In order to determine the most dominant factor contributing to chlorineresistance, experiments were carried out under several conditions. The candidate factors included coating time, concentrationof coating solution, ionic strength, and salt types. In general, as the coating time and concentration increased,the chlorine resistance increased for any salt used. Among the three materials, PVSA showed the greatest chlorineresistance of ca. 62,000 ppm·h, under the determined conditions, ionic strength (IS)=0.2 Mg and coating time of60 s. The order of chlorine stabilities for the coating materials was determined to be PVSA, PEI, and PVA. It wasfound that the chlorine resistance of any polymer-coated membrane is superior to the pristine RO membrane.

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