Polyvinyl chloride/quaternized poly phenylene oxide substrates supported thin-film composite membranes: Enhancement of forward osmosis performance

Quaternized poly phenylene oxide (QPPO) was synthesised and used as a modifier material to blend with polyvinyl chloride (PVC) to cast the substrate for thin-film composite (TFC) forward osmosis (FO) membranes. The addition of QPPO improved the porosity, hydrophilicity , and morphology of the substrate, thereby weakening the internal concentration polarisation of TFC membranes . Furthermore, the introduction of QPPO improved the structure of the active layer , which led to higher water permeability. Moreover, the mechanical properties of the TFC membranes were significantly improved after the introduction of QPPO. As a result, introducing QPPO significantly increased the FO performance. In addition, the TFC membrane based on a 40% QPPO blend ratio exhibited optimal FO performance: a high water flux of 71.21 L h −1  m −2 and an extremely low specific reverse solute flux of 0.079 g L −1 under the active layer facing the draw solution (DS) mode by utilising 1 M NaCl as the DS and deionised (DI) water as the feed solution; this FO performance remained fairly stable during long-term operation. This study suggests that introducing QPPO into the substrate is a sensible strategy for fabricating high-performance TFC FO membranes.