LAUSR

Abstract Macrovoid-free polyethersulfone/sulfonated polysulfone (PES/SPSf) ultrafiltration (UF) membranes containing oxidized multi-walled carbon nanotubes (O-MWCNTs) were fabricated via a non-solvent induced phase separation method using H2O and PEG 20 kDa as a non-solvent additives. The results show that the fully sponge-like morphology of the PES/SPSf membranes could be achieved as the content of O-MWCNTs in the casting solutions was increased, due to the formation of strong hydrogen bonds between SPSf, H2O, PEG 20 kDa and O-MWCNTs. Such morphology provided excellent mechanical strength properties with the highest of 4.02 ± 0.08 MPa obtained for the membrane containing 0.1 wt% O-MWCNTs. Microscopic analysis revealed homogenous distribution of O-MWCNTs in the PES/SPSf mixed-matrix membranes. Moreover, pure water flux initially increased from 598 to 713 L/m2 h followed by a decline to 590, 560, 553 and 578 L/m2 h as the content of O-MWCNTs was increased from 0 wt% to 0.005, 0.01, 0.03, 0.05 and 0.1 wt%, respectively. A rejection of > 99.9% for bovine serum albumin (BSA) was achieved by membranes containing 0.05 wt% O-MWCNTs. The water flux recovery ratio of membranes containing O-MWCNTs was found to be higher (> 90%) than that of pristine PES/SPSf (75%) even after the second fouling and cleaning stages. Furthermore, it was found that only 85% of E. coli bacteria were killed by pristine PES/SPSf, compared to 99% by PES/SPSf membrane containing the highest O-MWCNT loading. The fabricated flat-sheet membranes display attractive features for use as UF membranes in the pre-treatment stage of water treatment.