Thin film nanocomposite membranes based on imologite nanotubes blended substrates for forward osmosis desalination

Novel thin film nanocomposite (TFN) membranes were fabricated by interfacial polymerization on imogolite nanotubes (INTs) blended substrates for the forward osmosis (FO) desalination. INTs as intrinsically hydrophilic nanotubes were synthesized and characterized to be with length of 100-200 nm, outer diameter of 2 nm, and inner diameter of 1 nm. Then, different INTs loading (0.33, 0.66 and 1.0 wt%) were used to prepare INTs blended polysulfone (PSf) substrates, whose morphology and properties were investigated in detail. It is found that the incorporation of INTs obviously enhanced the hydrophilicity, pure water flux, overall porosity, surface porosity and roughness of PSf substrates. The TFN membranes demonstrated superior water permeance and salt rejection compared to the thin film composite (TFC) membranes. Among others, TFN 0.66 with 0.66 wt% INTs blended PSf substrate showed the best over-all properties which are important for demonstrating good osmotic performance in FO. Moreover, TFN membranes presented smaller structural parameters than TFC membrane, which means that internal concentration polarization (ICP) effect can be alleviated by incorporating hydrophilic INTs into substrates. The obtained TFN membranes with INTs blended substrates could develop opportunities in desalination.