Improved Performance and Mitigated Internal Concentration Polarization of Thin-Film Composite Forward Osmosis Membrane with Polysulfone/Polyaniline Substrate

Thin-film composite (TFC) membranes have been widely used in forward osmosis for desalination and water treatment. Nonetheless, the dilemma between selectivity and permeability and serious internal concentration polarization (ICP) still limits the filtration efficiency of TFC-FO membranes. Herein, a high-efficiency TFC-FO membrane was synthesized by embedding a polysulfone (PSf)/polyaniline (PANI) coblend membrane as the substrate. Impacts of PANI on both the substrate and the TFC-FO membrane were investigated by optimizing the concentration of PANI in substrates. The results indicated that the addition of PANI can adjust the properties of substrates, producing substrates with better hydrophilicity and improved porosity. This further mitigated the interfacial polymerization process and reduced the polyamide layer thickness. Compared to the pristine PSf-based TFC-FO membrane and the commercial FO membrane, the PSf/PANI-based TFC-FO membrane with 0.6 wt% PANI loading exhibited significantly enhanced water flux (209%) and decreased specific salt flux (40%). Moreover, the addition of PANI into substrates effectively mitigated the ICP phenomenon of the PSf/PANI-based TFC-FO membrane, with a 290% lower structure parameter (S) than that of the pristine TFC-FO membrane. This work offers an effective strategy to enhance the filtration capabilities of TFC-FO membranes by tuning substrate properties.