Reverse osmosis performance of homopolymers and copolymers of poly(amide-sulfonamide)s

Ten homopolymers and 15 copolymers of poly(amide-sulfonamide)s were synthesized by low-temperature solution polycondensation of five different diamines with isophthalopyl chloride/terephthaloyl chloride in N,N-dimethylacetamide. The general reverse osmosis (RO) performance of these new membrane materials were investigated by a systematic screening test with 270 ppm nickel ion industrial waste as the feed solution. A copolymer series based on 2,5-dimethylpiperazine, 1,3-diaminopropane and terephthaloyl chloride emerged as the best polymer system in terms of RO separation characteristics. Optimization of membrane fabrication of one of this series, with a 7:3 ratio of the two diamines was carried out by fixing the evaporation temperature at 65 degrees C and varying the evaporation time and casting solution composition. The RO tests for the membrane were performed at 20 kg cm(-2) operating pressure on three different feed solutions. Membranes showed salt rejection of up to 98.6 and 94.3% at a flux of 13 cm per day for nickel and sodium ion feeds, respectively. Copyright (C) 1996 Elsevier Science Ltd.