SYNTHESIS AND CHARACTERIZATION OF AFFINITY MEMBRANES MADE FROM POLYSULFONE

Polysulfone was chemically modified by a metalation reaction which cou ld be further reacted with glycidyl-4-oxohexylether. Thus, the final p olymer contained a reactive epoxy group with a 7-atom distance from th e polymeric backbone. From this modified polysulfone, asymmetric ultra filtration membranes were cast conventionally and iminodiacetic acid w as bonded to the epoxy group. The reaction was proved by electrokineti c measurements. The membranes, now with chelating properties, were com plexed with copper ions. By this method a high-performance affinity ma trix was obtained which was used for the adsorption of various amino a cids. Using histidine the complexation constant was determined to log K = 4.34 (phosphate buffer, pH 7, c(NaCl) 1 M). The affinity membranes were used for concentrating a dilute histidine solution (c = 4 mumol/ l) as well as for the separation of a solution consisting of four amin o acids.