Selective Capture Mechanism of Radioactive Thorium from Highly Acidic Solution by a Layered Metal Sulfide

Lei Xu, Chao Xu, Hongliang Bao, Ioannis Spanopoulos, Weijun Ke, Xue Dong, Chengliang Xiao*, Mercouri G. Kanatzidis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Thorium as a potential nuclear fuel for the next-generation thorium-based molten salt reactors holds significant environmental and economic promise over the current uranium-based nuclear reactors. However, because thorium (Th4+) usually coexists with other rare earth elements, alkali or alkaline earth metals in minerals, or highly acidic radioactive waste, seeking acid-resistant sorbents with excellent selectivity, high capacity, and fast removal rate for Th4+ is still a challenging task. In this work, we investigated a robust layered metal sulfide (KInSn2S6, KMS-5) for Th4+ removal from strong acidic solutions. We report that KMS-5 could capture Th4+ from a 0.1 M HNO3 solution with extremely high efficiency (∼99.9%), fast sorption kinetics (equilibrium time < 10 min), and large distribution coefficient (up to 1.5 × 106 mL/g). Furthermore, KMS-5 exhibited excellent sorption selectivity towards Th4+ in the presence of large amounts of competitive metal ions like Eu3+, Na+, and Ca2+. This extraordinary capture property for Th4+ is attributed to the facile ion exchange of Th4+ with K+ in the interlayers and subsequent formation of a stable coordination complex via Th-S bonds. These results indicate that KMS-5 is a promising functional sorbent for the effective capture of Th4+ from highly acidic solutions.

Original languageEnglish (US)
Pages (from-to)37308-37315
Number of pages8
JournalACS Applied Materials and Interfaces
Volume13
Issue number31
DOIs
StatePublished - Aug 11 2021

Keywords

  • acid-resistant sorbent
  • EXAFS
  • ion exchange
  • layered metal sulfide
  • thorium capture

ASJC Scopus subject areas

  • Materials Science(all)

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