Construction of SiO2@MWNTs incorporated PVDF substrate for reducing internal concentration polarization in forward osmosis

This work provides a facile and effective way of incorporating SiO2@MWNTs in polyvinylidene fluoride (PVDF) substrate to alleviate the internal concentration polarization (ICP) impact of the resultant thin film composite forward osmosis (TFC-FO) membranes for the first time. The in-situ decoration of multi-walled carbon nanotubes (MWNTs) using tetraethyl orthosilicate (TEOS) as precursor was conducted, resulting in improved hydrophilicity and the excellent dispersion of synthesized SiO2@MWNTs in PVDF membrane substrates accordingly. Effects of the SiO2@MWNTs concentration on the morphologies and properties of the modified substrates, and further impact on the polyamide (PA) layer structure are investigated via various characterizations. Besides, the intrinsic separation properties and forward osmosis performance of resultant TFC-FO membranes are also systemically studied. In comparison with the control TFC membrane, SiO2@MWNT-modified TFC membranes exhibit higher water fluxes with the enhanced membrane selectivity, as indicated by the decreased JS/JV values (from 1.10 to 0.19 g/L). This work therefore presents an alternative approach to prepare TFC-FO membranes with enhanced water flux as well as increased selectivity.