Efficacy of CNT-bound polyelectrolyte membrane by spray-assisted layer-by-layer (LbL) technique on water purification

Abstract

This study demonstrates the properties of surface-modified polyethersulfone (PES) composite ultrafiltration (UF) membranes prepared by a spray-assisted layer-by-layer (LbL) technique. The coating layers on the PES substrate consist of polyelectrolyte multilayers (PEMs) with and without functionalized multiwall carbon nanotubes (f-MWCNTs) as the blending additive. The composite membrane acquired a negative surface charge and the hydrophilicity of the membrane increased after adding hydrophilic f-MWCNTs. The pure water permeation tests revealed that the water flux was dependent on the f-MWCNTs/polyelectrolyte weight ratio and the number of PEMs. The prepared membrane showed slower flux reduction and lower fouling ratio (R_t) by humic acid (HA) filtration tests. Moreover, the flux recovery ratio (FRR) after deionized (DI) water flushing was improved significantly (up to 81%) compared with the PES substrate (46%), which indicated the enhancement of anti-fouling properties. The current work presents a facile way to modify the commercial membrane surface with tuned water flux and enhanced anti-fouling properties.