Design anion regulated layered double hydroxide and explore its theoretical mechanism of immobilizing uranium

Wencai Cheng; Huiping Tang; Tang Kai; Ruixuan Zhao; Junfeng Wang; Congcong Ding

doi:10.1016/j.jhazmat.2022.129352

Design anion regulated layered double hydroxide and explore its theoretical mechanism of immobilizing uranium

J Hazard Mater. 2022 Sep 5:437:129352. doi: 10.1016/j.jhazmat.2022.129352. Epub 2022 Jun 15.

Authors

Wencai Cheng¹, Huiping Tang¹, Tang Kai¹, Ruixuan Zhao¹, Junfeng Wang¹, Congcong Ding²

Affiliations

¹ Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, PR China; National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China; School of National Defence Science & Technology, Southwest University of Science and Technology, Mianyang 621010, PR China.
² Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, PR China; National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China. Electronic address: dingc_3650483@163.com.

PMID: 35897180
DOI: 10.1016/j.jhazmat.2022.129352

Abstract

It is momentous to comprehensively understand the anion's effect during the formation of Mg-Al layered double hydroxide (LDH), especially relating to the long-term disposal of uranium-containing (UO₂²⁺) residue. In this research, the CO₃^2-, PO₄^3- and SO₄^2- anions were inserted into the LDH's interlayer driven by its reconstructive memory effect. The UO₂²⁺ removal capacity increased in order (typically SO₄^2- < PO₄^3- < CO₃^2-). This was further confirmed by the bond length of U-S, U-P and U-C data acquired by theoretical calculation. The SEM-EDS showed anion-regulated LDH materials got fleecy and facilitated the insertion of anions. The increased average pore size and volume of calcined LDH provided convenient access for anions to easily enter interlayer. XRD results showed inserted interlayer anions could increase the interlayer spacing and expose more active sites, which was conducive to the removal of UO₂²⁺. The FTIR combined with theoretical calculation results certified anions could grasp UO₂²⁺. XPS results gave a compelling evidence that the amount of anion insertion was proportional to UO₂²⁺ removal capacity. In short, the anions could significantly improve LDH to the removal of UO₂²⁺ by the mechanism of surface and interlayer complexation. What was discovered can better evaluate the environmental behavior of UO₂²⁺ influenced by anion factors.

Keywords: Anion; Complexation; Immobilization; Layered double hydroxide; Uranium.