Effect of vapor-induced phase separation on the morphology and separation performance of polysulfone hollow fiber membranes

PSf hollow fiber membranes were fabricated by a dry/wet spinning process. The morphology and separation performances of the fibers were found to be strongly affected by air gap and ambient humidity. Macrovoids in the membranes disappeared, reappeared, and redisappeared with increasing air gap. The air gap required for the suppression and resuppression of macrovoids decreased with increasing ambient humidity.