A chitosan/dopamine-TiO2 composite nanofiltration membrane for antifouling in water purification

A major obstacle for the development of the cellulose-based nanofiltration membrane is its fouling. In this study, a novel cellulose-based composite nanofiltration membrane (CS/DA-TiO2-NFM) with excellent anti-fouling performance was prepared through casting of both chitosan (CS) and TiO2 modified by dopamine (DA-TiO2) on the cellulose substrate membrane. DA-TiO2 was successfully introduced into the surface of membrane, resulting in significant improvement in its hydrophilicity due to the formation of dense CS layers. Furthermore, both CS and DA-TiO2 were effective antimicrobial agents (against E. coli 90.6% and S. aureus 95.1%) that could minimize the accumulation of bacteria on the CS/DA-TiO2-NFM. For the antifouling test against BSA, the irreversible recovery ratio of the CS/DA-TiO2-NFM was only 23.25% of the control (no CS/DA-TiO2 modified NFM). In addition, the CS/DA-TiO2-NFM exhibited an increased rejection rate of MgSO4 (enhanced 40.93%) and water-flux (enhanced 18.10%) compared with the control. These results highlight the potential of the presented approach for designing membranes with effective separation performance and antifouling for drinking water treatment.