Dual-functional reverse osmosis membranes: A novel Approach to Combat biofouling with enhanced antibacterial and Antiadhesion properties

Biofouling is inevitable when reverse osmosis (RO) membrane is applied in water treatment. The adhesion and proliferation of microorganisms on the membrane surface severely degrade the performance of RO membrane, including a sharp decrease in permeate flux, a decline in salt rejection, and a shortened service life. Based on the biofouling mechanism, we designed and prepared a dual-functional RO membrane with excellent antibacterial and anti-adhesion properties by simultaneously grafting ionic liquid and sulfonic acid monomers onto the surface of RO membrane using a simple redox radical polymerization. Compared with the pristine membrane, the water flux of the grafted membrane increased by 13.0 %, and the salt rejection slightly increased. Meanwhile, the grafted membrane possessed good antibacterial activity against E. coli and S. aureus. The bacterial mortality rates increased from 20.3 % and 80.0 % of the pristine membrane to 98.2 % and 96.1 %, respectively. Comparing the changes in membrane flux and rejection before and after bacterial fouling, the grafted membrane had significant advantages over the pristine membrane. The grafted membrane also exhibited excellent antifouling ability towards bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA). After 10 h of continuous filtration experiment, the flux decline of membrane for HA and BSA solutions was about 7 %, for SA solution about 14 %. And the grafted membrane showed good long-term stability in the application of tap water purification. This study provides an innovative path for preparing RO membrane with excellent anti-biofouling capabilities.