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

摘要

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 % TiO2-PHEMA in the substrate exhibited a finger-like structure combined with sponge-like structure, while those with lower or without TiO2-PHEMA content showed fully finger-like structures. As for FO performance, the TFC-FO membranes with 3 wt % TiO2-PHEMA content achieved the highest water flux of 42.8 LMH and 24.2 LMH against the DI water using 2M 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 TiO2-PHEMA content in membrane substrate, indicating the reducing of internal concentration polarization. (C) 2016 Wiley Periodicals, Inc.