Fabrication and Characterization of Poly (phenyl sulfone) Ultrafiltration Membrane by VIPS Method

In this paper, the effect of Vapor-Induced Phase Separation (VIPS) time on the morphology and performance of poly (phenyl sulfone) membranes was investigated. 14 wt.% dope solutions were employed for membrane fabrication. After casting the solution, the formed polymeric film was exposed to humid air for certain times to form a porous structure. Morphology and performance of membranes were characterized by Scanning Electron Microscopy (SEM), pore size distribution, pure water flux, and Bovine Serum Albumin (BSA) retention. Pore size distribution results showed that by an increase in VIPS time, the pore size of the membrane was increased, and SEM images showed that with increasing VIPS time, the thickness of the dense skin top layer decreased, also the surface of the membranes at first became smooth and then changed to rough. Moreover, by increasing the VIPS time, the pure water flux of the prepared membranes increased from 17.12 to 37.61 L/m².h. The performance of the fabricated membranes for retention of BSA indicated that with increasing the VIPS time, the retention of BSA decreased gradually from 71.3 to 52.3% but the flux increased more sharply from 6.94 to 17.36 L/m².h. Generally, vapor induced phase separation technique is an effective method that could be applied for fabricating membranes with different characteristics for different applications from one dope solution. If a membrane with antifouling features is required, low VIPS time should be applied and if a high flux membrane is desirable, high VIPS time should be employed.