Synergistic integration of ε-polylysine and bacterial cellulose: High-flux ultrafiltration membranes with long-term antibacterial performance for drinking water

Generally, ultrafiltration (UF) membranes suffer from insufficient antibacterial cycles when dealing with biofouling. Herein, a new antibacterial sustainable material was synthesized from bacterial cellulose (BC), which was esterified with ε-polylysine (BC&ε-PL). The results confirmed that the grafting of ε-PL on BC reversed the zeta potential of BC from -20 mV to 30 mV. The BC&ε-PL incorporated polyether sulfone (PES) membrane exhibited a denser pore distribution and higher hydrophilicity compared with the pure PES membrane. Interestingly, membrane flux was increased from 73 L·m-2·h-1 for PES to 166 L·m-2·h-1 for PES-BC&ε-PL. More importantly, dynamic antibacterial experiments demonstrated an inhibition rate of over 80 % for PES-BC&ε-PL and its long-term antibacterial stability. The results confirmed the cell rupture and bacterial death as the antibacterial mechanism of the membrane. Theoretical XDLVO calculations confirmed that the electrostatic adsorption force was significantly lower for dead bacteria, preventing their deposition and ultimately effectively overcoming biofouling. This study provided a new direction for generating highly performing sustainable membranes for drinking water and offered a novel fabrication process of a long-term antibacterial UF membrane.