MXene-Modified Forward Osmosis Membrane with Enhanced Water Flux and PFAS Rejection from Landfill Leachate

Forward osmosis (FO) is a promising membrane technology for removing emerging contaminants in water, whereas its applications remain limited by low water flux, internal concentration polarization (ICP), and fouling. To address these issues, in this study, thin-film composite (TFC) membranes were fabricated by incorporating MXene nanosheets, a two-dimensional transition metal carbide, into the polyethersulfone (PES) support layer, followed by interfacial polymerization to form a polyamide active layer. The membranes were characterized using FTIR, FESEM, EDX mapping, AFM, zeta potential analysis, and water contact angle measurements to evaluate their chemical structure, surface morphology, MXene distribution, surface roughness, surface charge, and hydrophilicity. MXene addition (0.25-2 wt %) increased porosity, pore size, and hydrophilicity of the support layer, while excessive loading (4 wt %) resulted in pore blockage and compromised support-layer properties. The optimized TFC membrane (TFC-MX2, 2 wt %) achieved a water flux of 27.4 L·m-2·h-1, 201.1% higher than that of the unmodified membrane (TFC-Pristine), while maintaining a low reverse salt flux of ∼3.14 g·m-2·h-1 in normal FO mode. The structural parameter decreased by 72.5%, suggesting reduced ICP effects and improved support-layer transport characteristics. The TFC-MX2 membrane achieved 97.8 and 96.6% average rejection of perfluoroalkyl and polyfluoroalkyl substances (PFAS), as model micropollutants, in synthetic PFAS solutions and landfill leachate, respectively, while exhibiting reduced fouling propensity compared with TFC-Pristine. Overall, the findings demonstrate that MXene-modified FO membranes represent a promising approach for enhancing PFAS rejection in FO applications.