Impact of solvents and process conditions on the formation of polyethersulfone membranes and its fouling behavior in lake water filtration

BACKGROUND: The existence of natural organic colloids causes membrane fouling, which decreases the flux rate. Hence, membrane modification and lake water pretreatment were carried out to improve membrane performance. In this study, important preparation parameters such as solvents (N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP)), coagulant bath temperature (CBT) (10, 20 and 30 °C) and coagulant (sodium dodecyl sulfate SDS): 0.5, 1.0 and 1.5 g L⁻¹) were optimized for the fabrication of high flux polyethersulfone (PES) membrane. Cloisite was used for the pretreatment of lake water. RESULTS: The highest water permeability and pore radius of 393.03 × 10⁻⁹ m s⁻¹ kPa⁻¹ and 4.43 nm, respectively, were observed for the PES/DMAc membrane combination at coagulant bath temperature of 10 °C and non-solvent containing 1.5 g L⁻¹ SDS solution. Morphology analysis also displayed large pore size and macrovoid formation for such combination. Pretreated lake water had highest natural organic matter (NOM) rejection of 93% for PES/DMF membrane made at a coagulant bath temperature of 20 °C and non-solvent containing water. CONCLUSION: High flux PES membrane formation is achieved through the DMAc solvent with SDS as non-solvent solution at lower coagulation bath temperature. Pretreated lake water showed an increase of membrane flux and fouling resistance.