Ultrafiltration membrane modified via synergistic integration of quaternary ammonium compounds bactericidal activity and g-C3N4 photocatalysis: Toward superior antibiofouling and self-cleaning property

Fouling, particularly biofouling caused by microbial adhesion and subsequent biofilm formation, limits the widespread applications of membrane-based technologies. Although integrating contact-killing agents ( i.e., quaternary ammonium compounds, QACs) to fabricate antibiofouling membranes has been proven as an effective approach to mitigate this issue, the long-term effectiveness of the modified membranes after foulants covering remains a challenge. Herein, hydrophilic photocatalyst nanosheet g-C 3 N 4 (NCN) was introduced into QAC-modified ultrafiltration (UF) membranes to address this limitation. Results showed that the hydrophilic surface of NCN can improve the antiadhesion properties of hydrophobic QAC modified membranes. Moreover, NCN can degrade organic and inorganic pollutants on QAC modified membrane surface under visible light, thereby restoring the antibacterial ability of QAC. Furthermore, the composite QAC/NCN modified membrane demonstrated long-term stability with sustained remarkable antibacterial performance even after numerous fouling-chemical cleaning cycles. These findings underscore the efficacy of the synergistic integration of contact-killing bactericidal activity and photocatalysis as a versatile and promising solution for combating biofouling, thereby contributing to the advancement of membrane technology in environmental remediation applications.