Chelating effect between uranyl and pyridine N containing covalent organic frameworks: A combined experimental and DFT approach

Ruoxuan Guo; Yang Liu; Yingzhong Huo; Anrui Zhang; Jiahui Hong; Yuejie Ai

doi:10.1016/j.jcis.2021.08.118

Chelating effect between uranyl and pyridine N containing covalent organic frameworks: A combined experimental and DFT approach

J Colloid Interface Sci. 2022 Jan 15;606(Pt 2):1617-1626. doi: 10.1016/j.jcis.2021.08.118. Epub 2021 Aug 24.

Authors

Ruoxuan Guo¹, Yang Liu¹, Yingzhong Huo¹, Anrui Zhang¹, Jiahui Hong¹, Yuejie Ai²

Affiliations

¹ MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, PR China.
² MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, PR China. Electronic address: aiyuejie@ncepu.edu.cn.

PMID: 34500163
DOI: 10.1016/j.jcis.2021.08.118

Abstract

Covalent organic frameworks (COFs) are promising adsorbents for removing heavy metal ions, and have high crystallinity, a porous structure, and conjugated stability. N-containing functional groups are known to have great affinity for uranyl ions. In this work, to explore the peculiarity of the pyridine N structure as an efficient adsorbent, we chose 2,2'-dipyridine-5,5'-diamine (Bpy) and pyridine-2,5'-diamine (Py) as the core skeletons, and 1,3,5-triformylphloroglucinol (Tp) as the linker to synthesize two crystalline and stable N-containing COFs named TpBpy and TpPy, respectively, through a facile solvothermal method. Characterization results demonstrated that TpBpy and TpPy possessed regularly growing pore sizes, large specific surface areas and relatively strong thermal resistances. The results of batch experiments showed that both COF materials were capable of the effective removal of uranyl with uptake capacities of 115.45 mg g^-1 and 291.79 mg g^-1, respectively. In addition, density functional theory (DFT) simulations highlighted the beneficial chelation effect of the double N structure in pyridine monomers for removing uranyl ions. Combining systematic experimental and theoretical analyses, the adsorption process and interaction mode of porous COFs and UO₂²⁺ were revealed, to provide predictable support for the application of pyridine N-containing COFs in the field of environmental remediation.

Keywords: Adsorption; Covalent organic framework; Density functional theory (DFT) methods; Pyridine; U(VI).