Thin film composite forward osmosis membranes with poly(2-hydroxyethyl methacrylate) grafted nano-TiO2 as additive in substrate

The poly(2-hydroxyethyl methacrylate) grafted titanium dioxide nanoparticles were synthesized and added to the substrate of flat-sheet thin film composite forward osmosis (TFC-FO) membranes. The hydrophilicity of substrate was improved, which was advantageous to enhance the water flux of TFC-FO membranes. The membranes containing a 3 wt % TiO 2 -PHEMA in the substrate exhibited a finger-like structure combined with sponge-like structure, while those with lower or without TiO 2 -PHEMA content showed fully finger-like structures. As for FO performance, the TFC-FO membranes with 3 wt % TiO 2 -PHEMA content achieved the highest water flux of 42.8 LMH and 24.2 LMH against the DI water using 2 M NaCl as the draw solution tested under the active layer against draw solution (AL-DS) mode and active layer against feed solution (AL-FS) mode, respectively. It was proven that the hydrophilic property of membrane substrates was a strong factor influencing the water flux in FO tests. Furthermore, the structural parameter was remarkably decreased with an increase of TiO 2 -PHEMA content in membrane substrate, indicating the reducing of internal concentration polarization. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43719.