Highly efficient actinide(III)/lanthanide(III) separation by novel pillar[5]arene-based picolinamide ligands: A study on synthesis, solvent extraction and complexation

Yimin Cai; Seraj A Ansari; Kuirong Fu; Beichen Zhu; Haoyang Ma; Lixi Chen; Steven D Conradson; Song Qin; Haiying Fu; Prasanta K Mohapatra; Lihua Yuan; Wen Feng

doi:10.1016/j.jhazmat.2020.124214

Highly efficient actinide(III)/lanthanide(III) separation by novel pillar[5]arene-based picolinamide ligands: A study on synthesis, solvent extraction and complexation

J Hazard Mater. 2021 Mar 5:405:124214. doi: 10.1016/j.jhazmat.2020.124214. Epub 2020 Oct 8.

Authors

Affiliations

¹ Key Laboratory of Radiation Physics and Technology of the Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu 610064, China.
² Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
³ Department of Complex Matter, Jozef Stefan Institute, 1000 Ljubljana, Slovenia; Department of Chemistry, Washington State University, Pullman, WA 99164, USA.
⁴ Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
⁵ Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. Electronic address: mpatra@barc.gov.in.
⁶ Key Laboratory of Radiation Physics and Technology of the Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu 610064, China. Electronic address: wfeng9510@scu.edu.cn.

PMID: 33129604
DOI: 10.1016/j.jhazmat.2020.124214

Abstract

Selective extraction of highly radiotoxic actinides(III) is an important and challenging task in nuclear wastewater treatment. Many proposed ligands containing S or P atoms have drawbacks including high reagent consumption and possible secondary pollution after incineration. The present work reports five novel pillar[5]arene-based extractants that are anchored with picolinamide substituents of different electronic nature by varying spacer. These ligands reveal highly efficient separation of actinides(III) over lanthanides(III). Specifically, almost all of these ligands could extract Am(III) over Eu(III) selectively at around pH 3.0 (SF_Am/Eu>11) with fast extraction kinetics. Variation of the pyridine nitrogen basicity via changing para-substitution leads to an increase in the distribution ratios by a factor of over 300 times for Am(III) with an electron-withdrawing group compared to those with an electron donating group. Investigation of complexation mechanism by slope analysis, NMR, IR, EXAFS, and DFT techniques indicates that each ligand binds two metal ions by pyridine nitrogen and amide oxygen. Finally, these ligands do not show obvious decrease in both extraction and separation ability after being exposed to 250 kGy absorbed gamma radiation. These results demonstrate the potential application of pillar[5]arene-picolinamides for actinide(III) separation.

Keywords: Picolinamide extractants; Pillararene; Radioactive nuclear waste; Solvent extraction.

Publication types

Research Support, Non-U.S. Gov't