Ultrafast\nand Highly Selective Sequestration of Radioactive\nBarium Ions by a Layered Thiostannate

As a simulant of hazardous <sup>226</sup>Ra<sup>2+</sup>, the simultaneously\nselective and rapid elimination of radioactive <sup>133</sup>Ba<sup>2+</sup> ions from geothermal water is necessary but still challenging.\nIn this paper, we demonstrated the usability of a layered thiostannate\nwith facile synthesis and inexpensive cost, namely, K<sub>2<i>x</i></sub>Sn<sub>4–<i>x</i></sub>S<sub>8–<i>x</i></sub> (KTS-3, <i>x</i> = 0.65–1), for\nthe remediation of radioactive <sup>133</sup>Ba<sup>2+</sup> in multiple\nconditions, including sorption isotherm, kinetics, and the influences\nof competitive inorganic/organic ions, pH values, and dosages. KTS-3\nhas a strong barium uptake ability (171.3 mg/g) and an ultrafast adsorption\nkinetics (about 2 min). Impressively, it can achieve a high preference\nfor barium regardless of the excessive interference ions (Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, and humic acid)\nand acidic/alkaline environments, with the largest distribution coefficient <i>K</i><sub>d</sub> value reaching 6.89 × 10<sup>5</sup> mL/g.\nAlso, the Ba<sup>2+</sup>-laden products can be easily eluted by a\nconcentrated KCl solution, and its adsorption performances for barium\nresist well even after five consecutive cycles. In addition, owing\nto the regular appearance and excellent mechanical strength, the prepared\nKTS-3/PAN (PAN = polyacrylonitrile) granule displays a good removal\nefficiency in the flowing ion-exchange column. These advantages mentioned\nabove render it very promising for the effective and efficient cleanup\nof radioactive <sup>133</sup>Ba<sup>2+</sup>-contaminated wastewater.