Highly selective and easily regenerated novel PVDF/KCTS porous beads for the sustainable removal of cesium from wastewater

Removing 137Cs from nuclear wastewater with abundant coexisting ions at low concentrations has always been meaningful and challenging. This work synthesized a novel adsorbent K1.9Cr0.2Sn2.79S7 (KCTS) for the first time by Cr-doping using a two-dimensional [Sn3S7]n2n− anion layer as a template. The stability and adsorption performance of the doped materials were significantly enhanced. The powder material (KCTS) was coated with PVDF to obtain the composite microspheres, facilitating its industrial application. The optimized PVDF/KCTS microspheres reached adsorption equilibrium within 40 min with an adsorption capacity of 402.86 mg g−1 and exhibited broad acid-base tolerance and superior selectivity. Subsequently, the PVDF/KCTS microspheres were placed in the Cs-containing geothermal water to simulate the Cs removal process. The distribution coefficient of Cs+ is as high as 11627.91 mL g−1 and the separation factors (αMCs) between Cs+ and other ions ranged from 403.22 to 1120.22. In addition, efficient regeneration of the adsorbent was achieved through the elution of NaNO3.The adsorption performance did not attenuate notably after 10 cycles. PVDF/KCTS is a novel composite adsorbent that can be used for large-scale Cs removal and enrichment in wastewater.