Enhancing silica scaling resistance of high-pressure reverse osmosis membranes through surface grafting with various sulfonic acid monomers

Silica scaling is a major challenge in the application of high-pressure reverse osmosis (RO) membranes. In this work, we modified commercially available RO membranes by grafting different sulfonic acid monomers onto their surface using redox polymerization. We systematically studied the effects of various sulfonic acid monomers on membrane performance. Due to the different grafting abilities of sulfonic acid monomers on the membrane, the modified membranes exhibited different physicochemical properties. Simulated silica scaling experiments revealed that the initial permeate flux and sulfonic acid grafting rate of the membrane played crucial roles in its antifouling performance. Molecular dynamics (MD) simulation indicated that the adsorption of silica scale on the membrane was positively correlated with the grafting degree of sulfonic acid monomers. The membrane modified with 3-sulfopropyl potassium methacrylate (SPM) demonstrated a 14 % higher initial flux than the pristine membrane and the highest sulfonic acid grafting rate, resulting in the lowest flux decay rate. Additionally, the SPM modified membrane outperformed the pristine membrane against composite foulants with organic matters and silica. Our research demonstrated that the redox grafting polymerization of sulfonic acid monomers can simultaneously improve the flux and silica scaling resistance of RO membranes without compromising salt rejection. This provides a scalable strategy for preparing RO membranes with enhanced resistance to silica scaling.