Bimetallic MIL-101(Fe,Cu) Metal–Organic Framework (MOF) embedded in PVDF membrane for Fenton-like catalytic degradation of dye wastewater

Abstract

Bimetallic MIL-101(Fe,Cu) metal-organic frameworks with different Fe:Cu molar ratios were successfully synthesized and evaluated for the photocatalytic and photo-Fenton removal of Reactive Red 239 (RR239) dye wastewater. The synthesized catalysts were characterized using XRD, FTIR, SEM, EDS, and XPS analyses, which confirmed the successful incorporation of Cu while retaining the crystallinity, morphology, and functional properties of MIL-101(Fe). The results demonstrated that low Cu doping enhanced dye removal performance, with Fe:Cu ratios of 4:1 and 6:1 achieving removal efficiencies of 95.2% and 96.5%, respectively, exceeding that of monometallic MIL-101(Fe). The optimized MIL-101(Fe,Cu) catalysts were incorporated into PVDF to fabricate mixed matrix membranes. The fabricated membranes exhibited excellent photo-Fenton decolorization performance, achieving over 90% dye removal in the presence of visible light and H₂O₂. Dye decolorization increased with increasing MIL-101(Fe,Cu) loading and was effective over a wide pH range, with higher efficiency under acidic conditions. The membranes maintained good reusability over five cycles and demonstrated excellent self-cleaning properties. However, increased TOC and metal ion leaching suggested partial membrane or MOF degradation during prolonged photo-Fenton operation. Overall, the results indicate that MIL-101(Fe,Cu)/PVDF mixed matrix membranes are promising materials for the photo-Fenton treatment of dye-contaminated wastewater.