Sulfonated Reverse Osmosis Membrane with Simultaneous Mitigation of Silica Scaling and Organic Fouling

Inorganic scaling and organic foulingremain limiting factors forthe further application of reverse osmosis (RO) membranes. Herein,a novel monomer, 2,2 & PRIME;-benzidinedisulfonic acid (BDSA), wasselected as a comonomer with m-phenylenediamine (MPD)to fabricate RO membranes. Compared with the polyamide (PA) compositemembrane, the as-prepared PA-BDSA composite membrane exhibited enhancedsurface hydrophilicity and a smoother, more negative charge (zetapotential of -44.4 mV at pH 7). During the 24 h antiscalingexperiment with a saturated silica solution (SiO2 concentrationof 168 ppm), the water flux decline rate of the PA-BDSA-0.2 membranewas only 18%, which was 10% lower than that of the PA membrane (28%).During antifouling and scaling-fouling experiments, the PA-BDSA membranesalso displayed less flux loss than the PA membrane, indicating itssimultaneous alleviation of organic fouling and silica scaling. Theanalysis of the fouling layer revealed that compared to the PA membrane,fewer contaminants adhered to the PA-BDSA membrane surface. Furthermore,the interactions between silica and organic foulants were investigated,and the synergy of sodium alginate (SA) and silica aggravated foulingand scaling processes, resulting in a more serious flux decline rate.This research reveals a simple and practical method for the preparationof RO membranes to mitigate membrane scaling and fouling.