Theoretical and experimental investigations of enhanced uranium(VI) adsorption using a nitrogen doping strategy

Yanqing Guo; Meng Xia; Kexin Shao; Guangming Xu; Wei Cheng; Zhaorong Shang; Hao Peng; Yanguo Teng; Junfeng Dou

doi:10.1039/d2cp01386j

Theoretical and experimental investigations of enhanced uranium(VI) adsorption using a nitrogen doping strategy

Phys Chem Chem Phys. 2022 Jul 21;24(28):17163-17173. doi: 10.1039/d2cp01386j.

Authors

Yanqing Guo¹, Meng Xia¹, Kexin Shao¹, Guangming Xu¹, Wei Cheng², Zhaorong Shang³, Hao Peng³, Yanguo Teng¹, Junfeng Dou¹

Affiliations

¹ College of Water Sciences, Beijing Normal University, Beijing 100875, China. doujf@bnu.edu.cn.
² Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
³ Nuclear and Radiation Safety Center, Ministry of Ecology and Environment, Beijing 100082, China.

PMID: 35792077
DOI: 10.1039/d2cp01386j

Abstract

With the ongoing development and utilization of nuclear energy, uranium pollution has become an increasingly serious issue. Although many adsorbents are able to remove hexavalent uranium (U(VI)) from aqueous solution, the development of a high capacity adsorbent exhibiting superior stability would be beneficial. Grafting poly(amidoxime) (PAO) onto reduced graphene oxide (rGO) provides suitable U(VI) adsorption performance but the PAO is prone to agglomeration. The present work used density functional theory calculations to predict that PAO would bond with pyrrolic N atoms in nitrogen-doped rGO (N-rGO). To confirm this, PAO-grafted rGO (PAO-rGO) and PAO-grafted N-rGO (PAO-N-rGO) were prepared and characterized and the successful grafting of PAO on N-rGO was demonstrated. Adsorption experiments demonstrated that PAO-N-rGO exhibit superb U(VI) adsorption performance compared with the original PAO-rGO under acidic conditions. As for competing metal ions, Cu²⁺, Al³⁺, and Ca²⁺ have a greater impact on U(VI) adsorption than Na⁺, Mg²⁺, and K⁺ both for PAO-rGO and PAO-N-rGO. The maximum adsorption capacities of PAO-rGO and PAO-N-rGO for U(VI) were calculated to be 1500.26 and 1545.95 mg g^-1, respectively. The mechanism of nitrogen doping promoting uranium(VI) adsorption can be attributed to enhanced PAO grafting and improvement of adsorption performance of the rGO. This work demonstrates that nitrogen doping is a viable strategy for enhancing the U(VI) adsorption performance of PAO-rGO.