Design of an ionic PVDF-based additive for PVDF water purification membranes with anti-fouling and bactericidal activities

Multifaceted bio-contamination, such as protein fouling and microbial proliferation is one of the most critical obstacles to the use of hydrophobic membranes in water purification. To overcome, we herein developed ionic PVDF membranes that exhibit simultaneous antifouling and bactericidal properties. Two different PVDF-based additives, containing only a cationic component (i.e., PVDF-QDMA) and a zwitterionic-co-cationic component (i.e., PVDF-MPC/QDMA), were successfully synthesized and added to PVDF dope solutions for membrane formation via non-solvent induced separation. It was found that low additive loadings of 5 and 10 wt% significantly altered the membrane properties, including its porosity, hydrophilicity, surface charge, and pure water permeance. Among the prepared PVDF membranes, that containing 10 wt% PVDF-MPC/QDMA gave the optimal performances in terms of both antifouling (flux recovery ratio ≈ 100%) and bactericidal properties (>99.9% against S. aureus and P. aeruginosa). These comprehensive biofouling-resistant properties therefore render our polymeric additive design a potential strategy for coping with the underwater biofouling of PVDF membranes.