Highly Efficient Removal of Uranium from Aqueous Solution Using a Magnetic Adsorbent Bearing Phosphine Oxide Ligand: A Combined Experimental and Density Functional Theory Study

It is still a great challenge to develop magnetic adsorbents for the highly efficient entrapment of uranium from aqueous solution. Herein, a novel magnetic adsorbent (denoted as Fe₃O₄/P (AA-MMA-DVP)) bearing phosphine oxide ligand was designed and synthesized via a DPE (1,1-diphenylethylene) method based on DPE as radical controlling agent, showing an excellent adsorption capacity for uranium at pH 4.5 and outstanding selectivity in aqueous media including 14 coexisting ions. The magnetic adsorbent showed a q_max value of 413.2 mg g^–1 at 298 K and pH 4.5, which was higher than that of most of other magnetic adsorbents. The outstanding selectivity (S_u = 95.8%) for uranium was reasonably ascribed to the strong complexation between UO₂²⁺ and PO groups anchored on the polymer skeletion, which was evidenced by experimental results. Furthermore, the magnetic adsorbent could be isolated by magnetic force and be recycled at least five times without significant loss in adsorption capacity. This work provided a convenient synthetic route to develop a novel magnetic adsorbent with high capacity and strong selectivity for the entrapment of uranium from aqueous solution.