A ternary mechanism for the facilitated transfer of metal ions onto metal–organic frameworks: implications for the "versatility" of these materials as solid sorbents  

作　　者：Xiyuan Bu Ming Tian Hongqing Wang Lin Wang Liyong Yuan Weiqun Shi 

机构地区：[1]Laboratory of Nuclear Energy Chemistry,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China [2]School of Chemistry and Chemical Engineering,University of South China,Hengyang 421001,China

出　　处：《Frontiers of Chemical Science and Engineering》2022年第11期1632-1642,共11页化学科学与工程前沿（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.U20B2019,21790373 and 21790370);the National Science Fund for Distinguished Young Scholars(Grant No.21925603).

摘　　要：Although metal–organic frameworks offer a new platform for developing versatile sorption materials,yet coordinating the functionality,structure and component of these materials remains a great challenge.It depends on a comprehensive knowledge of a“real sorption mechanism”.Herein,a ternary mechanism for U(Ⅵ)uptake in metal–organic frameworks was reported.Analogous MIL-100s(Al,Fe,Cr)were prepared and studied for their ability to sequestrate U(Ⅵ)from aqueous solutions.As a result,MIL-100(Al)performed the best among the tested materials,and MIL-100(Cr)performed the worst.The nuclear magnetic resonance technique combined with energy-dispersive X-ray spectroscopy and zeta potential measurement reveal that U(Ⅵ)uptake in the three metal–organic frameworks involves different mechanisms.Specifically,hydrated uranyl ions form outer-sphere complexes in the surface of MIL-100s(Al,Fe)by exchanging with hydrogen ions of terminal hydroxyl groups(Al-OH_(2),Fe-OH_(2)),and/or,hydrated uranyl ions are bound directly to Al(Ⅲ)center in MIL-100(Al)through a strong inner-sphere coordination.For MIL-100(Cr),however,the U(Ⅵ)uptake is attributed to electrostatic attraction.Besides,the sorption mechanism is also pH and ionic strength dependent.The present study suggests that changing metal center of metal–organic frameworks and sorption conditions alters sorption mechanism,which helps to construct effective metal–organic frameworks-based sorbents for water purification.

关 键 词：U(Ⅵ) metal–organic frameworks adsorption mechanism metal node 

分 类 号：O62[理学—有机化学]