Selective removal of cesium from wastewater by salt-resistant hydrogel fiber-supported Al-doped tin sulfide

Abstract

The extreme pH and complex composition of radioactive wastewater pose great challenges to the chemical stability and properties of adsorbents. Herein, three kinds of metal-doped tin sulfides were developed by a simple one-pot method for cesium removal. DFT calculations combined with experiments were conducted to reveal their structures, stability, and adsorption properties. It was found that the crystal structures of tin sulfide became more stable after doping by Ni and Al. Particularly, the Al-doped material (NAlSS) exhibited the highest stability and adsorption performance because of the highest −COHP value of the Sn-S bond in NAlSS and the low binding energy between NAlSS and Cs⁺. The industrial application of the powdery NAlSS was further solved by wet spinning using glutaraldehyde cross-linked sodium alginate and hydroxyethyl cellulose (SHG) as the supporters. The obtained salt-resistant hydrogel fibers (SHG-NAlSS) exhibited excellent adsorption performance and stability in wide pH (2 ∼ 12) and temperature (298.15 ∼ 328.15 K) ranges. The maximum adsorption capacity reached 401.34 mg·g⁻¹ within 10 min. The material was successfully applied for Cs⁺ removal from wastewater, and the distribution coefficient of Cs⁺ reached 255020.33 mL·g⁻¹. After 10 adsorption–desorption cycles, the adsorbent maintained good stability. These results, along with the fixed-bed adsorption, demonstrate that the developed material can be used as a candidate for Cs⁺ removal from radioactive wastewater.