Tannic acid-metal oxide modified polyethersulfone membranes for dye wastewater treatment using micellar-enhanced ultrafiltration

Industrial growth has led to an increase in wastewater production, and dye pollutants pose a significant environmental problem. Membrane technology is widely used for wastewater treatment because it can effectively separate dye contaminants. In this study, tannic acid (TA) and metal oxide (MO) nanoparticles (TiO₂, SiO₂, and ZrO₂) were added to polyethersulfone (PES) membranes to improve their performance. Micellar Enhanced Ultrafiltration (MEUF) was employed to treat dye wastewater and mitigate membrane fouling. TA-MO nanoparticles were prepared, and four types of membranes were fabricated: pristine PES, PES-TA-TiO₂, PES-TA-SiO₂, and PES-TA-ZrO₂, with additive concentrations of 0.5 and 1 wt%. The membranes were first evaluated using FT-IR, water contact angle, and water permeability tests to determine the best additive concentration. Further characterization was carried out using SEM, EDX, AFM, porosity, and mechanical strength analyses. Filtration tests were conducted using a surfactant-assisted dye solution. Membrane performance was evaluated based on water flux, COD removal, dye rejection, and fouling resistance. The results demonstrate that membranes containing 1 wt% additive exhibited superior performance compared to those with 0.5 wt%, particularly in terms of higher water flux, improved dye rejection, enhanced COD removal, and better antifouling properties (higher flux recovery and lower irreversible fouling). Furthermore, the 1 wt% PES-TA-ZrO₂ membrane showed the most optimal overall performance, especially in terms of flux stability and fouling resistance, indicating its suitability for dye wastewater treatment.