Performance and antifouling behavior of thin-film nanocomposite nanofiltration membranes with embedded silica spheres

We synthesized silica particles with varying sizes of 50, 200, and 500 nm. These particles were added to a trimesoyl chloride (TMC) solution and used as fillers to produce thin-film nanocomposite (TFN) polyamide membranes through interfacial polymerization. The effect of the particle size and concentration on the nanofiltration membrane performance was systematically investigated. Scanning electron microscopic images showed that small particles were dispersed in the membrane with spaces between them, but large particles clustered together and gathered into a crowd or mass, forming a layer of particles. When the particle concentration was low (0.35 g silica/g TMC), TFN50 (membrane with 50-nm particles, the smallest of the additives used in this study) delivered the highest pure water flux (58.3 ± 3.8 L m−2 h−1); the salt rejection [RNa2SO4 (99.0 ± 0.6%) > RMgSO4 (96.5 ± 2.6%) > RMgCl2 (67.2 ± 1.3%) > RNaCl (42.6 ± 2.3%)] was comparable with that for the other membranes. At a high concentration of particles (0.75 g silica/g TMC), the water flux delivered by membranes that differed in the size of embedded particles was the same; however, the salt rejection decreased with increasing particle size. In antifouling tests with bovine serum albumin used as model foulant, membranes with silica particles indicated high water flux recovery and remarkable antifouling property.