Synergistic effect of silica nanoparticles in the matrix of a poly(ethylene glycol) diacrylate coating layer for the surface modification of polyamide nanofiltration membranes

In this study, a commercial polyamide nanofiltration membrane was modified by a combination of poly(ethylene glycol) diacrylate (PEGDA) in situ polymerization and silica (SiO₂) nanoparticles. The PEGDA layer was polymerized on the surface of the membranes alone or mixed with SiO₂ nanoparticle. The surface modification influence on the water flux, salt rejection, and antifouling behavior was investigated. The effects of the nanoparticles and PEGDAylation on the membrane properties were characterized by Fourier transform infrared spectroscopy, contact angle measurement, and scanning electron microscopy analyses. The membranes that were in contact with 30 wt % PEGDA and then treated with ultraviolet light for 5 min had a better water flux than the unmodified membrane. The fouling resistance of the membranes to a foulant solution containing bovine serum albumin, humic acid, and sodium sulfate were studied, and the results show that the membrane with 30 wt % PEGDA had better antifouling properties. After the weight percentage of PEGDA for the prepolymerization solution was optimized (30 wt % was the best), the SiO₂ nanoparticle concentration in the prepolymerization matrix was optimized. The presence of SiO₂ nanoparticles in the PEGDA layer increased the membrane flux. The maximum water flux and good antifouling properties were obtained for 0.5 wt % SiO₂ nanoparticles in a 30 wt % PEGDA layer.