A Two-Dimensional Thiotitanate Ion Exchanger with High Cs<sup>+</sup> Removal Performance

A Two-Dimensional Thiotitanate Ion Exchanger with High Cs<sup>+</sup> Removal Performance

<sup>137</sup>Cs is a persistent <i>β</i>/<i>γ</i>-emitter (<i>t</i><sub>1/2</sub> = 30.1 years) generated from <sup>235</sup>U and <sup>239</sup>Pu fission. It is a critical challenge to efficiently capture <sup&...

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Bibliographic Details
Main Authors:	Chang Wei, Shaoqing Jia, Yingying Zhao, Jiating Liu, Haiyan Sun, Meiling Feng, Xiaoying Huang
Format:	Article
Language:	English
Published:	MDPI AG 2025-04-01
Series:	Separations
Subjects:	thiotitanate cesium ion exchange single crystal structure radionuclide remediation
Online Access:	https://www.mdpi.com/2297-8739/12/5/104
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Summary:	<sup>137</sup>Cs is a persistent <i>β</i>/<i>γ</i>-emitter (<i>t</i><sub>1/2</sub> = 30.1 years) generated from <sup>235</sup>U and <sup>239</sup>Pu fission. It is a critical challenge to efficiently capture <sup>137</sup>Cs<sup>+</sup> for nuclear waste management due to its high solubility, environmental mobility, and propensity for biological accumulation. Herein, we prepare a two-dimensional (2D) thiotitanate Rb<sub>0.32</sub>TiS<sub>2</sub>·0.75H<sub>2</sub>O (denoted Rb-TiS<sub>2</sub>) using a special molten salt synthesis method, “Mg + RbCl”. Rb-TiS<sub>2</sub> can selectively capture Cs<sup>+</sup> from aqueous solutions. Its structure features a flexible anionic thiotitanate layer with Rb<sup>+</sup> as counter ions located at the interlayer spaces. As an ion exchanger, it possesses high adsorption capacity (<i>q</i><sub>m</sub><sup>Cs</sup> = 232.70 mg·g<sup>−1</sup>), rapid kinetics (the removal rate <i>R</i> > 72% within 10 min), and a wide pH tolerance range (pH = 4–12) for Cs⁺ adsorption. Through a single-crystal X-ray structural analysis, we elucidated the mechanism of Cs⁺ capture, revealing the ion exchange pathways between Cs⁺ and Rb<sup>+</sup> in Rb-TiS<sub>2</sub>. This work not only provides an important reference for the synthesis of transition metal sulfides with alkali metal cations but also proves the application prospect of transition metal sulfides in radionuclide remediation.
ISSN:	2297-8739