High performance polyvinylidene fluoride membrane functionalized with poly(ionic liquid) brushes for dual resistance to organic and biological fouling

Abstract

The balance between antifouling properties and permeability is an inevitable problem for the application of ultrafiltration membranes. Herein, hydrophilic poly(ionic liquid) (PIL)-functionalized PVDF membranes with organic foulant resistance and bacterial killing properties were developed via atom transfer radical polymerization (ATRP). PILs with different anions bromide ([Br]-), tetrafluoroborate ([BF4]-) and hexafluorophosphate ([PF6]-) were functionalized onto the membrane surface, which all showed microbial inactivation ability. By optimizing PIL anions and ATRP conditions, a C4BF4-M membrane with favorable antibacterial and hydrophilic surface properties was obtained, which showed dual resistance to organic and biological fouling. With bovine serum albumin (BSA) and E. coli as model foulants, dynamic filtration tests further confirmed that PIL-M membranes have favorable anti-organic and anti-biological fouling abilities. Compared with the pristine PVDF membrane, the stable water flux of the C4BF4-M membrane increased up to 56% and 32%, respectively, during the anti-organic and anti-biological fouling experiments. The surface plasmon resonance confirmed that very loose binding can be formed between BSA and PIL brushes, leading to the excellent anti-organic fouling performance of the C4BF4-M membrane. We further evaluated the practical application and substantially reduced the fouling potential of the PIL-M membrane by wastewater effluent filtration tests. The results confirm that the surface grafting of PIL brushes is a promising method for membrane fouling control.