Novel montmorillonite-sulfur composite for enhancement of selective adsorption toward cesium

The selective elimination of radioactive cesium from complicated wastewater is imperative in view of environment and human health. Montmorillonite has been accepted as one of the most promising adsorbents for cesium purification. However, its poor selectivity still remains a major challenge. Herein, a novel montmorillonite-sulfur composite was developed via a facile one-step solvent-free method and used for Cs⁺ removal. Owing to the fact that soft Lewis base S^2- ligand interacted more strongly with softer Lewis acid Cs⁺ than other cations, the capacity and selectivity towards Cs⁺ was significantly enhanced. In this case, a large capacity of 160.9 mg g^-1 was achieved. The distribution coefficient value (∼4000 mL g^-1) was 3-times larger than that of pristine montmorillonite (∼1500 mL g^-1). Moreover, this composite could be easily recycled and reused within five times recycling experiments. Therefore, this low-cost and facilely prepared composite are expected to be used for the selective removal of Cs⁺ from complicated wastewater containing various competing ions.