Green synthesis of a potential magnetic and mesoporous EG-nZVI/CA-MCM41 nanocomposite for reductive sorption of europium

Abstract

Europium is the “rarest” rare-earth element in the earth's crust. Nanocomposite-mediated adsorptive extraction of europium is very promising due to its cost-effectiveness and environmental acceptability. A newfangled ethylene glycol nano zerovalent iron supported citric acid modified MCM41 (EG-nZVI/CA-MCM-41) nanocomposite was synthesized employing green tea extracts. The structural and morphological characterization of the prepared nanomaterials was carried out by XRD, FTIR, XPS, FE-SEM, and EDS analysis. Under optimal conditions (i.e., pH 5.2, 40 °C), the nanocomposite could remove 91.5% Eu(III) from an initial dose of 750 mg L⁻¹, yielding an extraordinarily high sorption capacity of 714.28 mg g⁻¹. While the best fit Freundlich isotherm (R²: 0.955) suggests monolayer adsorption, the kinetic analysis indicates a chemisorption process. Rapid adsorption through electrostatic interaction followed by reduction at the nZVI surface could be the mechanism for Eu(III) removal. The green synthesized nanocomposite also has significant reusability capacity for up to 3 consecutive cycles.