The performance of novel reverse osmosis membranes made from poly-2-vinylimidazoline. I.
Novel thin-film composite reverse osmosis (RO) membranes were fabricated by the interfacial polycondensation of poly-2-vinylimidazoline precursors and the aromatic acid chloride crosslinking agents: 3-(chlorosulphonyl) benzoyl chloride, 3,5-di(chlorosulphonyl)benzoyl chloride and benzene-1,3,-dicarboxylic acid dichloride. Three different forms of precursor were used, the difference depending on their methods of preparation. In aqueous solution, the poly-2-vinylimidazoline precursor was partially hydrolyzed and contained some N-aminoethylamide groups. Membranes were tested for salt retention and permeate flux, first under standard conditions and then tubular membranes were tested under severe conditions. The latter comprised: low and high pH, elevated temperature, elevated pressure and chlorinated feed solutions. Tubular membranes, optimized for high retention and flux, gave RO performances of up to 98.2±0.7% retention and a flux of 23.3±6.3 1/m2 membrane area per hour (lmh) when tested at 2 MPa with a 2000 mg/l NaCl feed solution at 20°C. These membranes were not stable at low pH and high chlorine levels. © 1992.