Morphological and performance evaluation of highly sulfonated polyethersulfone/polyethersulfone membrane for oil/water separation

This study includes the fabrication of highly sulfonated polyethersulfone (SPES)/polyethersulfone (PES) blended membranes with superior properties for effective oil/water separation. In this regard membranes with different content of SPES and degree of sulfonation (DS) were fabricated. Highly sulfonated PES was synthesized by chlorosulfonic acid and concentrated sulfuric acid at low temperature. FTIR and DS analysis confirmed the presence of sulfonic acid groups on the PES backbone. The phase inversion process of membrane fabrication was studied by ternary phase diagram construction and dope solutions viscosity measurement. Fabricated membranes were characterized by SEM, water contact angle, porosity, pure water flux, and mechanical strength. The SEM images demonstrated that blended membranes have wider finger-like pores in their structure compared to bare PES membrane. Results indicated that by increasing SPES content and DS, permeability increased but mechanical strength decreased. The membranes fabricated by 50% SPES with 37% DS and 50% PES has the highest permeability (59.89 l/m2.h) with 93.3% oil rejection. Also antifouling properties of blended membranes improved remarkably compared to PES membrane.