Zhao Bin, Yuan Liyong, Wang Yue, Duan Tao, Shi Weiqun
National Co-Innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China.
Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):16300-16308. doi: 10.1021/acsami.1c00364. Epub 2021 Mar 31.
U(VI) and Eu(III), as representative elements of the hexavalent actinide and trivalent lanthanides (always as a chemical analogue for trivalent actinide), respectively, have attracted more and more attentions due to the widespread use of nuclear energy. Much effort has been focused on developing versatile materials for their uptake from aqueous solution. For the first time, we report here UiO-66 and its mono- (UiO-66-COOH) and di-carboxyl (UiO-66-2COOH) functional derivatives as robust adsorbents for efficient U(VI) and Eu(III) removal. It is found that the introduction of carboxyl groups greatly reduces the surface charge of UiO-66, thus guaranteeing excellent adsorption capacity at low pH. At pH = 3, for example, the adsorption capacity of UiO-66-2COOH for U(VI) and Eu(III) is more than 100 and 60 mg/g, respectively, while almost no adsorption occurs for pristine UiO-66. At pH = 4, both UiO-66-COOH and UiO-66-2COOH show high performance on U(VI) and Eu(III) removal. UiO-66-COOH has adsorption capacities of 80 and 43 mg/g for U(VI) and Eu(III), respectively, while the values for UiO-66-2COOH reach 150 and 80 mg/g, respectively. Also, all these materials achieve adsorption equilibrium within 100 min. More importantly, combining the needs of practical applications and the characteristics of high stability, high porosity, and excellent adsorption performance of UiO-66-2COOH, dynamic adsorption column experiments were successfully conducted; ∼99% U(VI)/Eu(III) can be efficiently adsorbed, and >90% adsorbed U(VI)/Eu(III) can be re-collected with dilute nitric acid solution, even after four adsorption-desorption cycles. The findings of this work demonstrate the application potential of metal-organic framework materials to remove radionuclides from environmental samples or nuclear waste liquids.
作为六价锕系元素和三价镧系元素（常作为三价锕系元素的化学类似物）的代表性元素，U(VI)和Eu(III)由于核能的广泛应用而受到越来越多的关注。人们致力于开发从水溶液中摄取它们的多功能材料。我们首次在此报道UiO-66及其单羧基（UiO-66-COOH）和二羧基（UiO-66-2COOH）功能衍生物作为高效去除U(VI)和Eu(III)的坚固吸附剂。研究发现，羧基的引入大大降低了UiO-66的表面电荷，从而保证了在低pH值下具有优异的吸附能力。例如，在pH = 3时，UiO-66-2COOH对U(VI)和Eu(III)的吸附容量分别超过100和60 mg/g，而原始的UiO-66几乎不发生吸附。在pH = 4时，UiO-66-COOH和UiO-66-2COOH在去除U(VI)和Eu(III)方面均表现出高性能。UiO-66-COOH对U(VI)和Eu(III)的吸附容量分别为80和43 mg/g，而UiO-66-2COOH的值分别达到150和80 mg/g。此外，所有这些材料在100分钟内达到吸附平衡。更重要的是，结合实际应用需求以及UiO-66-2COOH的高稳定性、高孔隙率和优异吸附性能的特点，成功进行了动态吸附柱实验；即使经过四个吸附-解吸循环，仍可高效吸附约99%的U(VI)/Eu(III)，并且用稀硝酸溶液可回收>90%吸附的U(VI)/Eu(III)。这项工作的结果证明了金属有机框架材料在从环境样品或核废液中去除放射性核素方面的应用潜力。
