Preparation and development of amidoxime-modified Fe₃O₄/SiO₂ core-shell magnetic microspheres for enhancing U(VI) adsorption efficiency from seawater

Abstract

<abstract> <p>We synthesized and characterized amidoxime-modified Fe₃O₄/SiO₂ core-shell magnetic microspheres tailored for maximal U(VI) sorption efficiency from seawater. Through meticulous structure and spectroscopy analyses, the microspheres, which were designed with amidoxime functionality, exhibited remarkable U(VI) sorption capabilities compared to raw silica-coated Fe₃O₄ counterparts. The maximum percent uranium adsorption (98.57%) was achieved at 60 minutes with 0.05 g of adsorbent, using a synthetic solution of 25 mg L⁻¹ UO₂(CH₃COO)₂. 2H₂O at pH 7 and 25 º C (298 K). The kinetic studies highlighted rapid equilibrium achieved within 1 hours. Following the pseudo-second-order model, the microspheres reflected a maximum sorption capacity of 24.286 mg g^-1 at pH 7 and 298 K. The U(VI)-loaded microspheres could be efficiently separated via an external magnetic field with adsorption efficiency of 91.67% at pH 6.5 and efficiently regenerated by HCl, indicating their potential for U(VI) preconcentration and separation from seawater. This research contributed to the development of high-performance sorbents for U(VI) removal and holds promise for solving the radioactive element elimination and enrichment, performing its stability, selectivity, and reusability across multiple cycles.</p> </abstract>