Tuning morphology and transport in ultrafiltration membranes derived from polyethersulfone through exploration of dope formulation and characteristics

Polymer concentration and solvent power are two significant variables in the dope formulation of asymmetric ultrafiltration membranes. In this study, polyethersulfone (PES) solutions in N-methyl-2-pyrrolidone (NMP) and dimethylformamide (DMF) as two solvents were prepared by non-solvent induced phase separation (NIPS). The influence of polymer concentration and solvent type on the morphology and the performance of the membrane are investigated under and above critical concentration and ternary phase diagram is studied for choosing appropriate solvent. The microstructure of the membranes were studied by Scanning electron microscopy (SEM), Brunaure–Emmitt–Teller (BET), Barrett–Joyner–Halenda (BJH). The performance of the PES membrane were analyzed by the flux and rejection tests. Experimental results reveal that the morphology of membranes is mainly influenced by interaction between solvent and non-solvent which determine the type of demixing and finally the structure. On the other hand, membranes derived from PES/NMP (16/84 wt%) have the highest rejection of 95.92% for BSA and pure water flux of 23.94 lit.m −2 .hr −1 than that of PES/DMF membrane. The findings of this research display that polymer concentration of 16wt% PES in NMP is the optimum dope formulation for constructing ultrafiltration membranes with an appropriate structure and better performance. The results prove that NMP is a suitable alternative to DMF as a solvent for PES ultrafiltration membranes owing to higher rejection of bovine serum albumin (BSA).