Surface modification of polyvinylidene fluoride membrane by atom-transfer radical-polymerization of quaternary ammonium compound for mitigating biofouling

Abstract

Fabrication of antibiofouling membrane is a vital but challenging task for the treatment of water and wastewater using membrane-based processes. In this work, quaternary ammonium compounds (QACs) were grafted onto polyvinylidene fluoride (PVDF) membrane via surface-initiated activators regenerated by electron transfer atom-transfer radical-polymerization (ARGET ATRP) method. Membrane surface characterization demonstrated that QAC was successfully grafted onto the PVDF membrane surface. The QAC-modified membrane (MQ) demonstrated prominent antimicrobial capability by destruction of cell integrity, with an inhibition rate ~98.3% of E. coli and ~98.5% of S. aureus, respectively. Batch filtration tests showed that MQ membrane had lower flux decline rate compared to control membrane (M0) under constant-pressure filtration. Confocal laser scanning microscopy analysis revealed that less total cells and more dead cells were present on MQ membrane compared to M0. The quantity of polysaccharides and proteins on MQ membrane was reduced as well. The grafted QAC on PVDF membrane also showed favorable stability during repeated fouling-cleaning tests. These results highlight that the ARGET ATRP method for grafting QAC onto polymeric membrane surface is a robust way to fabricate low-biofouling membrane for water and wastewater treatment.