In the present work, the influence of the lithium bromide (LiBr) additive on the performance of polyethersulfone (PES) membranes was studied using various formulations of dope solutions to which the microwave assistance (MWA) method was applied. The amount of PES was kept at 20 wt %, and the weight ratios of LiBr to dimethylformamide (DMF) were varied in the range 1-5 wt %. Results revealed that MWA irradiation increases the kinetics of dissolution of PES even in the presence of higher ratios of LiBr. It was found from viscosity, FTIR, water uptake, contact angle, and SEM-EDX analyses that the interaction between PES and LiBr is strongest when their mole ratio is unity. Performance data and the pore size distributions on the membrane surface have also been investigated. The structure of the MW casting solution under a strong interaction force attributed to the irradiation causes a decrease in the pore sizes and results in an increased rejection rate through the ultrafiltration membrane.

BACKGROUND: Generally the fabrication of polymeric membranes is a complicated and expensive process since it involves several steps. The preliminary preparation steps involve polymer drying and dissolution and is very time consuming and expensive. Currently, conventional electrothermal heating (CEH) is used to dissolve polyethersulfone in an aprotic solvent for membrane fabrication. Usually CEH requires 6 to 8 h at temperatures of 80 to 95• C. This paper reports the fabrication and characterization of polyethersulfone (PES) asymmetric ultrafiltration membrane made from microwave (MW) synthesis casting solution consisting of various compositions of double solvents and lithium bromide (LiBr) additive.