Electrospun MIL-101(Fe)/Graphene Oxide Nanofibrous Composites for Efficient Removal of Heavy Metals From Wastewater.

Abstract

Heavy metal contamination in industrial wastewater poses a critical environmental challenge due to the toxicity and persistence of metals such as Pb(II) and Cd(II). This study evaluated the performance of MIL-101(Fe)/Graphene Oxide (GO) electrospun nanofibrous membranes as advanced adsorbents for the efficient removal of these metal ions. Structural characterization confirmed a high surface area and uniform integration of MIL-101(Fe) and GO within the fibrous matrix. Batch adsorption experiments revealed maximum removal efficiencies of 93% for Pb(II) and 95% for Cd(II), with optimum performance observed at pH 5.5 and 6.0, respectively. The adsorption process followed pseudo-second-order kinetics (R² > 0.98), suggesting chemisorption, and was well described by both Langmuir (q_max: 126 mg/g for Pb(II), 100 mg/g for Cd(II); R² ≥ 0.98) and Freundlich isotherms (1/n < 1), indicating favorable monolayer and multilayer adsorption on heterogeneous surfaces. The thermodynamic analysis confirmed that adsorption was spontaneous (ΔG° values as low as -8.6 kJ/mol for Pb(II)) and endothermic (ΔH° values of 21.5 kJ/mol for Pb(II) and 18.9 kJ/mol for Cd(II)). In continuous flow systems, the membranes maintained removal efficiencies above 85% for both metals across 10 cycles at a flow rate of 10 mL/min. The membranes also exhibited excellent fouling resistance, with flux decline remaining below 10% over 5 cycles, and demonstrated high cleaning efficiency, recovering up to 99.2% of flux through simple deionized water rinsing. Reusability studies showed that the membranes retained over 80% of their original adsorption capacity after eight regeneration cycles in batch mode, and over 70% removal efficiency and 83% water flux after 10 regeneration cycles in real industrial wastewater conditions. These findings demonstrated the robustness, reusability, and scalability of MIL-101(Fe)/GO membranes for the effective treatment of heavy metal-contaminated industrial effluents. Future studies should explore membrane performance under mixed contaminant conditions and assess techno-economic feasibility at the pilot scale. PRACTITIONER POINTS: Advanced nanofibrous membranes with MIL-101(Fe)/Graphene Oxide (GO) tested for heavy metal removal. Outstanding performance compared to conventional adsorbents. 93% Pb(II) and 95% Cd(II) removal at optimum pH conditions (Pb(II): pH 5.5, Cd(II): pH 6.0). Rapid equilibrium kinetics with 60 minutes compared to 120 minutes. High surface area and optimal pore size critical for superior performance.