Antifouling Polysulfone/Multi-Walled Carbon Nanotube/Terbium Oxide Nanocomposite Nanofiltration Membrane for Dye Removal Applications

Polysulfone (PSF) nanofiltration membranes incorporating oxidized multi-walled carbon nanotubes (o–MWCNTs) and terbium oxide (Tb2O3) nanoparticles were fabricated via the non-solvent-induced phase inversion technique. The effect of Tb2O3 loading (0, 1, 3, and 5% w/w) on membrane morphology, hydrophilicity, water permeability, dye rejection, and antibiofouling performance was systematically investigated. Membrane structure was characterized by FTIR spectroscopy, SEM, EDX, XRD, and water contact angle measurements. The results confirmed the successful incorporation of Tb2O3 within the membrane matrix, and morphological analysis revealed a relatively dense membrane structure without macrovoid formation. Filtration experiments conducted in a dead-end cell under pressures of 1–4 bar demonstrated a maximum water flux of 53 L m−2 h−1, with dye rejection exceeding 99.9% for both methylene blue (MB) and Congo red (CR) at 4 bar. Antibiofouling performance, evaluated by colony-forming unit analysis, revealed bacterial growth reductions of 59% against Gram-negative Escherichia coli and 89% against Gram-positive Candida albicans, attributed to the dark-active generation of reactive oxygen species by Tb2O3, eliminating the need for UV irradiation. These results demonstrate that the synergistic integration of o–MWCNTs and Tb2O3 effectively addresses the permeability-selectivity trade-off and mitigates biofouling limitations associated with pristine PSF membranes, thereby offering a promising multifunctional platform for sustainable industrial wastewater treatment.