Green approaches to polysulfone based membrane preparation via dimethyl sulfoxide and eco-friendly natural additive gum Arabic

Abstract

Membrane technology has emerged as one of the important technologies for water and wastewater application. However, the current issues with membrane fabrication process is the utilization of conventional solvents that are not entirely safe and sustainable. Therefore, green approaches to membrane preparation which highlight on the minimal consumption of conventional hazardous solvents, additives and low energy requirement during membrane fabrication process is desirable. Prior to the adoption of this green approaches, selection of green solvents and its effect on membrane performance should be addressed. Hence, in this study, polysulfone (PSf) based membranes were prepared using green solvents in the presence of eco-friendly natural additive gum Arabic (GA). The membranes were fabricated via phase inversion method with 18 wt% of solvent concentration and 1.5 wt% additive concentration. To obtain suitable green solvents, screening was conducted by comparing the speed of dope solution formation using different green solvents namely cyrene, triethyl phosphate (TEP) and dimethyl sulfoxide (DMSO) under the consideration of minimal energy consumption. DMSO was selected for its low energy consumption during the preparation of dope solution, adequate stability, and satisfactory asymmetric membrane appearance. Next, the membranes were characterized through porosity, pore size and contact angle analyses. Results showed that, the presence of eco-friendly natural additive GA helped to enhance hydrophilicity and porosity of the membranes. Subsequently, membrane performance was measured through pure water flux and Congo red (CR) rejection capability and DMSO membrane displayed comparable membrane performance with membrane prepared by using conventional solvent, namely N-methyl-2-pyrrolidone (NMP). Associated with the improved hydrophilicity attributed to the presence of GA natural additive, both membranes prepared using DMSO and NMP showed substantial boost in their membrane performance. Afterward, membrane stability was measured via flux recovery ratio (FRR) and result showed that DMSO membrane in the presence of GA natural additive 93.29% FRR.