Ultrafast and Highly Selective Sequestration of Radioactive Barium Ions by a Layered Thiostannate

As a simulant of hazardous Ra-226(2+), the simultaneously selective and rapid elimination of radioactive Ba-133(2+) ions from geothermal water is necessary but still challenging. In this paper, we demonstrated the usability of a layered thiostannate with facile synthesis and inexpensive cost, namely, K2xSn4-xS8-x (KTS-3, x = 0.65-1), for the remediation of radioactive Ba-133(2+) in multiple conditions, including sorption isotherm, kinetics, and the influences of competitive inorganic/organic ions, pH values, and dosages. KTS-3 has a strong barium uptake ability (171.3 mg/g) and an ultrafast adsorption kinetics (about 2 min). Impressively, it can achieve a high preference for barium regardless of the excessive interference ions (Na+, K+, Mg2+, Ca2+, and humic acid) and acidic/alkaline environments, with the largest distribution coefficient K-d value reaching 6.89 x 10(5) mL/g. Also, the Ba2+-laden products can be easily eluted by a concentrated KCl solution, and its adsorption performances for barium resist well even after five consecutive cycles. In addition, owing to the regular appearance and excellent mechanical strength, the prepared KTS-3/PAN (PAN = polyacrylonitrile) granule displays a good removal efficiency in the flowing ion-exchange column. These advantages mentioned above render it very promising for the effective and efficient cleanup of radioactive Ba-133(2+)-contaminated wastewater.