FACTORS INFLUENCING THE PRODUCTION OF POLYETHERSULFONE MICROFILTRATION MEMBRANES BY IMMERSION PHASE INVERSION PROCESS

Polyethersulfone microfiltration (MF) membranes can be produced from p olyethersulfone/solvent/nonsolvent systems by the immersion phase inve rsion process in a water bath. When the casting solution composition i s adjusted close to phase separation, a fast gelation in water occurs which hinders further polymer enrichment at the interface between poly mer solution and water; an open-cell MF membrane structure is thus ret ained. Addition of a certain amount of a water-soluble polymer, polyvi nylpyrrolidone, to the casting solution will further change the demixi ng rate and gelation rate of the casting solution in water. Such an ad dition improves the open-cell structure of the membranes. Besides dope composition, the performance of these MF membranes is also dependent on the casting conditions.