Enhanced antifouling performance of ultra-thin antimicrobial peptide membrane through chemical-crosslinking layer-by-layer assembly.

Biofouling and microbial penetration are still the important issues for surface water purification during gravity-driven microfiltration process, where biofouling has the tendency to deteriorate microbial rejection efficiency. Herein, ultra-thin antimicrobial layer composed of ε-poly-l-Lysine (EPL) and tannic acid (TA) biomacromolecules was successfully chemically crosslinked onto polyvinylidene fluoride (PVDF) membrane via covalent bond-involved layer-by-layer (LbL) method. As-prepared PVDF@EPL membrane could kill bacteria through the contact sterilization effect of AMP. Besides, PVDF@EPL membrane rapidly raised the intracellular ROS (Reactive Oxygen Species) level of bacteria and caused oxidative damage. Accompanying, hydrogen peroxide was in-situ generated on PVDF@EPL membrane surface at the presence of dissolved oxygen, which was also related to sterilization effect. In addition, the biofouling resistance ability was further enhanced by the hydrophilicity of PVDF@EPL membrane. During microfiltration process of river water, PVDF@EPL membrane inhibited the adsorption and aggregation of bacterial cells on membrane surface and presented high stable permeate flux (114 % higher than commercial PVDF). More importantly, PVDF@EPL membrane achieved long-lasting > 99.99 % effluent disinfection efficiency. Chemical-crosslinking assembly of antimicrobial peptide and plant polyphenol offered an environmental-friendly and promising strategy for the construction of antibiofouling membrane surface in the field of gravity-driven membrane process.