Synergistic effect of highly porous microstructured support and co-solvent assisted interfacial polymerization on the performance of thin-film composite FO membranes

Internal concentration polarization (ICP) in a dense support layer is one of the main reasons holding back forward osmosis (FO) process. In this regard, a highly porous microstructured support (HPμS) featuring a quasi-sponge-free sublayer pore structure can be considered a suitable alternative to develop high-performance FO membranes. However, it has not been tested for its effects on FO. This study demonstrates that a TFC membrane prepared using the HPμS works out for FO by inducing 3.35 times higher water flux without compromising a reverse salt flux (Js) compared to a control TFC membrane prepared without support adjustment. The performance improvement could be achieved by HPμS's almost no sponge-like region and lateral walls, which were desirable to minimize ICP. Furthermore, we verified that it is possible to leverage co-solvent assisted interfacial polymerization (CAIP) to further improve FO membrane performances by creating a more permeable active layer. The in-house TFC membrane optimized by the HPμS and CAIP displayed 5.3 times higher FO water flux than the control membrane, while keeping comparable Js. We expect that this research could contribute to kicking the FO membrane performance up a notch by providing a practical example of simultaneous optimization of both support and active layers. [Display omitted] •A highly porous microstructured support (HPμS) successfully reduced ICP in FO.•Almost no sponge-like region and lateral walls of the HPμS were key in reducing ICP.•A sublayer structure of a support layer was examined by a non-destructive inspection.•Co-solvent assisted interfacial polymerization further improved FO performances.•The simultaneous optimizations of support and active layers maximized FO performances.