POLYSULFONE AFFINITY MEMBRANES FOR THE TREATMENT OF AMINO-ACID MIXTURES

Affinity membranes for the treatment of solutions containing amino aci ds were obtained via lithiating polysulfone that was subsequently conv erted with glycidylether. From this polymer asymmetric ultrafiltration membranes were cast. The membranes were reacted with iminodiacetic ac id yielding membranes fitted out with bidentate chelates. The same rea ction path was applied to commercially available symmetric microfiltra tion membranes. The chelate-bearing membranes were complexed with Cu, Ni, and Zn ions. For the experiments with amino acids only the Cu-comp lexed membranes were used. The complexation constants for histidine an d tryptophan for six different membranes were determined. Because of t he affinity of these two amino acids for the complexed Cu ions, they c ould easily be separated from solutions containing amino acids such as alanine, glycine, and valine. Also, concentrating very dilute amino a cid solutions was carried out successfully. (C) 1995 John Wiley & Sons , Inc.