MOF modified with copolymers containing carboxyl and amidoxime groups and high efficiency U (VI) extraction from seawater

Nuclear energy can effectively alleviate the carbon emission problem caused by fossil fuels. Herein, a highly effective uranium adsorbent MIL-101-SMA-AO modified with carboxyl and amidoxime groups was prepared by a surface-initiated atom transfer radical copolymerization (ATRP) of styrene and maleic anhydride on MIL-101 (Cr) and the subsequent amidoximation. MIL-101-SMA-AO shows ultra-high BET specific surface area (greater than1300 m2∙g−1) and high efficiency adsorption performance, the maximum uranium adsorption capacity reached 1086 mg·g−1. It also shows high selectivity for U (VI) in a simulated seawater and excellent recyclability, the uranium adsorption capacity slightly dropped after five adsorption/desorption cycles. The affecting factors of uranium adsorption process were investigated by batch adsorption experiments under different adsorption conditions. Besides, the results of adsorption kinetics and thermodynamics show that the adsorption process of MIL-101-SMA-AO on U (VI) is controlled by chemical rate and is monolayer adsorption. The synergistic effect of carboxyl and amidoxime groups on the strong chelation with uranium were thought to afford the adsorbent high adsorption property and selectivity for uranium. MIL-101-SMA-AO provides a valid and promising program for the study of uranium extraction from seawater.