Efficient enrichment of U(VI) by two-dimensional layered transition metal carbide composite

Abstract

Abstract With the rapid development of nuclear energy, how to safely and efficiently dispose of radioactive waste solution has become an urgent environmental problem of public concern. It is of great significance to construct a new type of high-efficiency adsorbent material to recover uranium from nuclear waste solution. In this work, the Ti3C2Tx material (an emerging two-dimensional inorganic layered material) with a stable layered structure was used as the matrix, and the amidoxime functionalized MXene composite material (PAO/Ti3C2Tx) was synthesized by in-situ polymerization. The amidoxime-functionalized Ti3C2Tx showed excellent capacity to capture U(VI), with a maximum adsorption capacity of 98.04 mg/g at 25 °C, which was significantly better than that of Ti3C2Tx, and the adsorption selectivity for U(VI) was greatly improved. The adsorption was conformed to Langmuir isotherm model and pseudo-second-order kinetic model. In addition, the adsorbed UO22+ could be effectively desorbed by 0.1 M HNO3, and the adsorption performance of PAO/Ti3C2Tx did not decrease significantly after 5 adsorption/desorption cycles. The results of ionic strength experiment, FT-IR, SEM, and XPS jointly indicated that adsorption mechanism of U(VI) on PAO/Ti3C2Tx was the combined effect of the amidoxime group and -O and -OH active groups on the surface of Ti3C2Tx, mainly inner complexation. These advantages make PAO/Ti3C2Tx composite a highly potential U(VI) adsorbent with great application prospects.