Ultrafast elimination of uranium from aqueous solution by convenient synthesis of phosphonic acid functionalized mesoporous carbon: A combined experimental and density functional theory study

Abstract

With the speedy advancement of nuclear power, it is strongly desirable to synthesize highly efficacious materials for eliminating uranium from abundant nuclear wastewater under nuclear leakage emergency conditions. Herein, a novel sorbent CMK-3/P (VPA) bearing phosphonic acid was successfully developed by in-situ polymerization of vinylphosphonic acid (VPA) in the presence of mesoporous carbon (CMK-3). Since abundant accessible phosphonic acid ligand had been led into the surface of the CMK-3, the sorbent showed an ultrafast adsorption rate for uranium. The kinetic process demonstrated that uranium adsorption equilibrium on CMK-3/P (VPA) was achieved even within 30 s, suggesting the adsorption rate of the prepared adsorbent far exceeded that of all other sorbents covered formerly. The prepared adsorbent also demonstrated high uranium sorption capacities, and the maximum adsorption capacity (qmax) under 4 M of HNO3 and pH of 4.5 reached 330.1 and 617.2 mg g−1 within 30 s, respectively. Besides, CMK-3/P (VPA) also presented an excellent uranium selectivity, environmental tolerance for uranium immobilization and good structural stability. The preeminent uranium adsorption behavior of CMK-3/P (VPA) was chiefly ascribed to the interplay of the phosphine acid with uranium, and the uranium sorption mechanism of the sorbent at pH of 4.5 was different from that at 4 M of HNO3, which was authenticated by X-ray photoelectron spectrum (XPS) analysis and density function theory (DFT) method. As a result, CMK-3/P (VPA) developed by this work might be seen as a prospective sorbent for eliminating uranium from various kinds of contaminated water under emergency situations.