High-performance thin-layer hydrogel composite membranes for ultrafiltration of natural organic matter

Abstract

Thin-layer hydrogel composite (TLHC) ultrafiltration (UF) membranes were synthesized by photo-grafting of either poly(ethylene glycol) methacrylate (PEGMA) or N, N-dimethyl-N -(2-methac ryloyloxyethyl- N-(3-sulfo propyl) ammonium betaine (SP E) onto commercial polyethersulfone (PES) UF membranes. The performance of TLHC UF membranes was evaluated for natural organic matter (NOM ) filtration and compared to commercial PES UF membranes. The fouling evaluation was done by investigation of membrane–solute interactions (adsorptive fouling) and membrane-€“solute-€“solute interactions (UF). The results sugg est that the TLHC membranes convincingly displayed a higher adsorp tive fouling resistance than unmodified PES UF membranes. In long-term stirred dead-end UF, a much lower fouling was observed for TLHC membranes than for commercial membranes with the same flux and rejection. Further, water flux recovery was also much higher. An analysis using an existing blocking model was perf ormed in order to eluci date the effect of a polymer hydrogel layer on fouling mechanism as well as cake layer characteristics. The TLHC membranes synthesize d by photo-g rafting of PEGM A (40 g/L) and PEGMA with a low concentration of cross-linker mon omer in the reaction mixture (ratio: 40/0.4 (g/L)/( g/L))showed a much better performance than the other composite membranes. Those membranes could reduce the cake resistance on the membrane surface. This work has relevance for the design of high-per formance UF membranes for applica tions in water treatment