Engineering a dual-functional sulfonated polyelectrolyte-silver nanoparticle complex on a polyamide reverse osmosis membrane for robust biofouling mitigation

Reverse osmosis (RO) is considered a promising technology for addressing global water scarcity problems. However, biofouling is still a significant obstacle in the operation of RO membranes. In this study, a sulfonated polyelectrolyte-silver nanoparticle architecture was employed to endow polyamide RO membranes with robust repelling-and-killing bacterial abilities. The RO membrane surface was first functionalized by poly (3-sulfopropyl methacrylate potassium salt) (pSM) via atom transfer radical polymerization (ATRP), followed by in situ immobilization of silver nanoparticles (AgNPs). Static bacterial adhesion and diffusion inhibition zone tests revealed that hydrophilic and electronegative pSM brushes repelled bacterial attachment on the membrane surface while AgNPs can inactivate bacterial cells. In addition, the presence of pSM-AgNPs complex on the RO membrane surface exhibited the best anti-biofouling properties, maintaining ~90% water flux in long-term dynamic biofouling filtration. Moreover, good trap of pSM brushes for AgNPs could guarantee the long-term stability of repelling-and-killing bacterial abilities.