Macrovoid-free PES/SPSf/O-MWCNT ultrafiltration membranes with Journal of Membrane Science 566 (2018) 288–300

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 spongelike 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 OMWCNTs. 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.