Cellulose acetate membranes fabricated by a combined vapor-induced/wet phase separation method: morphology and performance evaluation

Abstract

Cellulose acetate (CA) microfiltration membranes were fabricated by a combined vapor-induced and wet phase separation technique. A systematic morphology study was performed on the membranes prepared under different fabrication conditions and dope solution compositions. The results showed that symmetric CA membranes could be obtained by controlling relative humidity, temperature and exposure time during vapor-induced phase separation step. While the surface morphology and pore size of the membranes could be mainly tailored by adjusting the dope solution composition. The performance study of the membranes showed that for operation at low transmembrane pressures, only symmetric membranes fabricated by vapor-induced phase separation process have permeability which can be reached 100 L/m2h using polyvinylpyrrolidone with an average molecular weight of 30,000 (PVPK30) or polyethylene glycol with an average molecular weight of 400 (PEG400) as additives. Bacteria removal performance of the membranes showed that samples prepared at optimized solution compositions of CA/PVP and CA/PEG fabricated at constant vapor-induced phase separation (VIPS) condition of 5 min exposure time, 45 °C and 55% relative humidity can completely filtrate the E. coli bacteria. The prepared CA membranes showed no cytotoxicity in mouse L929 fibroblast cells, confirming their biocompatible nature for possible water treatment or biomedical applications.