MOLECULAR-WEIGHT CUTOFF CHARACTERISTICS O F PH-RESPONSIVE ULTRAFILTRATION MEMBRANES AGAINST MACROMOLECULE SOLUTION

pH-responsive ultrafiltration membranes were prepared from a copolymer of vinylpyridine and acrylonitrile. Different molecular weight cut-of f characteristics were obtained by varying the casting conditions (sol vent evaporation temperature and time) of the membrane. The water perm eability of the prepared membranes changed reversibly in response to t he pH shift of feed water in the range of pH 4 to 10. In the separatio n of aqueous solution of polyethylene glycols with different molecular weights, the volume and solute fluxes and molecular weight cut-off of the membrane increased with the increase of pH in feed solution. The separation of proteins (trypsin, protein A and immunogloblin G) from a queous solution was carried out and higher values of protein rejection were obtained at pH 4 than at pH 10.