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

Unconventional ion exchangers can achieve efficient removal of [UO 2 ] 2+, Cs +, and Sr 2+ ions from complex aqueous solutions and are of great interest for environmental remediation. We report two new gallium thioantimonates, [Me 2 NH 2 ] 2 [Ga 2 Sb 2 S 7 ]·H 2 O (FJSM-GAS-1) and [Et 2 NH 2 ] 2 [Ga 2 Sb 2 S 7 ]·H 2 O (FJSM-GAS-2), which present excellent ion exchange properties for [UO 2 ] 2+, Cs +, and Sr 2+ ions. They exhibit high ion exchange capacities for [UO 2 ] 2+, Cs +, and Sr 2+ 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 [UO 2 ] 2+ ion exchange (5 min for FJSM-GAS-1 and 15 min for FJSM-GAS-2, respectively). Both compounds display active ion exchange with [UO 2 ] 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 +, Ca 2+, and HCO 3 – . The distribution coefficient K d U of 6.06 × 10 6 mL/g exhibited by FJSM-GAS-1 is the highest among the reported U adsorbents. The [UO 2 ] 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 β and γ radiation resistance, make FJSM-GAS-1 and FJSM-GAS-2 promising for selective separations in nuclear waste remediation.