A low-cost and high-performance thin-film composite forward osmosis membrane based on an SPSU/PVC substrate

A low-cost sulfonated polysulfone (SPSU)/poly(vinyl chloride) (PVC) substrate based high-performance thin-film composite (TFC) forward osmosis (FO) membrane was fabricated in this work. The results showed that the morphologies of the substrates were looser and more porous, and the porosity, pure water permeability, surface hydrophilicity, and average pore size of the substrates significantly improved after the SPSU was introduced into the PVC substrates. Furthermore, the SPSU/PVC-based TFC membranes exhibited rougher, looser and less crosslinked polyamide active layers than the neat PVC-based TFC membrane. The water permeability obviously increased, and the structure parameter dramatically declined. Moreover, the FO performance significantly improved (e.g. the water flux of TFC2.5 reached 25.53/48.37 LMH under FO/PRO mode by using 1.0 M NaCl/DI water as the draw/feed solution, while the specific salt flux exhibited a low value of 0.10/0.09 g/L). According to the results, it can be concluded that 2.5% of SPSU was the optimal blend ratio, which exhibited the lowest sulfonated material blend ratio compared to the data reported in the literature. Hence, this is a feasible and low-cost fabrication approach for high-performance FO membrane by using the cheap PVC and low blend-ratio SPSU as the membrane materials.