Efficient Removal of [UO2]2+, Cs+, and Sr2+ Ions by Radiation-Resistant Gallium Thioantimonates

Unconventional ion exchangers can achieve efficient removal of [UO2](2+), Cs+, and Sr2+ ions from complex aqueous solutions and are of great interest for environmental remediation. We report two new gallium thioantimonates, [Me2NH2](2)[Ga2Sb2S7]center dot H2O (FJSM-GAS-1) and [Et2NH2](2)-[Ga2Sb2S7]center dot H2O (FJSM-GAS-2), which present excellent ion exchange properties for [UO2](2+), Cs+, and Sr2+ ions. They exhibit high ion exchange capacities for [UO2](2+), Cs+, and Sr2+ ions (q(m)(U) = 196 mg/g, q(m)(Cs) = 164 mg/g, and q(m)(Sr) = 80 mg/g for FJSM-GAS-1, q(m)(U) = 144 mg/g for FJSM-GAS-2) and short equilibrium times for [UO2](2+) ion exchange (5 min for FJSM-GAS-1 and 15 min for FJSM-GAS-2, respectively). Both compounds display active ion exchange with [UO2](2+) in the pH range of 2.9-10.5. Moreover, the sulfide compounds could maintain high distribution coefficients K-d(U) even in the presence of excess Na+, Ca2+, and HCO3-. The distribution coefficient K-d(U) of 6.06 X 10 6 mL/g exhibited by FJSM-GAS-1 is the highest among the reported U adsorbents. The [UO2](2+) laden products can be recycled by conveniently eluting the uranium with a low-cost method. These advantages combined with facile synthesis, as well as beta and gamma radiation resistance, make FJSM-GAS-1 and FJSM-GAS-2 promising for selective separations in nuclear waste remediation.