Biosynthesized Fe–Cu bimetallic nanocomposite: Characterization and arsenic remediation

Abstract

This study demonstrates the green synthesis of Fe-Cu nanocomposite using Azadirachta indica leaf extract and evaluates its efficacy for arsenic species removal from water. Structural characterization revealed the successful formation of mesoporous CuO and CuFe2O4 phases, with a BET surface area of 68.77 m2 g-1 and a point of zero charge (pHPZC) of 7.2. Systematic batch experiments revealed high adsorption capacities (98.90 mg g-1 for arsenate, 34.45 mg g-1 for arsenite), rapid kinetics and satisfactory performance over a wide range of pH. Isotherm, thermodynamic and kinetic analyses indicated chemisorption-governed, endothermic adsorption through multilayer formation. Mechanistic investigations using FTIR, Raman and XPS confirmed that arsenic adsorption proceeds primarily via surface complexation, electrostatic interactions and in-situ oxidation of arsenite mediated by redox-active Fe3+ and Cu2+ centres. The nanocomposite effectively reduced arsenic levels in simulated groundwater to below WHO limits, demonstrating applicability in real water. Regeneration studies showed partial recovery of adsorption capacity over four cycles using aqueous NaOH solutions, underscoring the economic viability. This material stands out for its eco-friendly synthesis, high efficacy and robust performance, offering promise for safe drinking water solutions in arsenic-affected regions.