Enhanced uranium separation by charge enabling γ-MnO2 with oxygen vacancies

Shuang Zhang; Fan Yang; Xiaohui Cao; Yong Tang; Taiqi Yin; Tao Bo; Yunhai Liu; Grzegorz Lisak; Naoki Kano; Bing Na; Mengyu Chang; Yuhui Liu

doi:10.1016/j.jhazmat.2023.132112

Enhanced uranium separation by charge enabling γ-MnO₂ with oxygen vacancies

J Hazard Mater. 2023 Oct 5:459:132112. doi: 10.1016/j.jhazmat.2023.132112. Epub 2023 Jul 22.

Authors

Shuang Zhang¹, Fan Yang², Xiaohui Cao², Yong Tang², Taiqi Yin³, Tao Bo³, Yunhai Liu², Grzegorz Lisak⁴, Naoki Kano⁵, Bing Na⁶, Mengyu Chang⁷, Yuhui Liu⁸

Affiliations

¹ Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices, East China University of Technology, Nanchang 330013 Jiangxi, China; State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013 Jiangxi, China.
² State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013 Jiangxi, China.
³ Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
⁴ School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141, Singapore, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
⁵ Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-Noch@, Nishi-ku, Niigata city, Niigata 950-2181, Japan.
⁶ Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices, East China University of Technology, Nanchang 330013 Jiangxi, China; State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013 Jiangxi, China. Electronic address: bna@ecut.edu.cn.
⁷ Departments of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston 77030 TX, USA. Electronic address: changmengyu14@gmail.com.
⁸ State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013 Jiangxi, China. Electronic address: liuyuhui@ecut.edu.cn.

PMID: 37494797
DOI: 10.1016/j.jhazmat.2023.132112

Abstract

Numerous efforts have been devoted to understanding the electron transfer process of uranium (UO₂²⁺) on adsorbent materials, whereas the potential oxygen vacancies (OVs) in metal oxides have long been overlooked. Once these interactions are taken into account, the emerging molecular orbital effects undoubtedly affect the adsorption process. Here, we synthesized CC/γ-MnO₂ by growing MnO₂ on carbon cloth (CC), followed by the creation of oxygen vacancies (OVs) through electrochemical methods to form CC/γ-MnO₂-OVs. The CC/γ-MnO₂-OVs shows significantly enhanced selectivity and durability for UO₂²⁺, with the maximum adsorption capacity increasing from 456.8 to 1648.1 mg/g (by a factor of 3.6). Theoretical calculations suggest that the generation of OVs leads to an increase in charge transfer and a decrease in adsorption energy between UO₂²⁺ and CC/γ-MnO₂, due to the interaction between Mn 3d orbital in CC/γ-MnO₂ and O 2p orbital in UO₂²⁺. The OVs in CC/γ-MnO₂ provide a spatial structure for anchoring the OU=O moiety of UO₂²⁺, while the surface van der Waals forces and the formation of chemical bonds between Mn-U contribute to charge interactions. This synergistic effect allows CC/γ-MnO₂-OVs to exhibit favorable selectivity, a large adsorption capacity, and rapid adsorption kinetics towards uranyl ions. This work achieves enhanced UO₂²⁺ separation by introducing OVs in CC/γ-MnO₂ through a facile electrochemical strategy, highlighting the great potential for nuclear waste processing.

Keywords: Charge transfer; First–principles calculations (DFT); Oxygen vacancies (OVs); Uranium; γ–MnO(2).