Efficient Removal of [UO 2 ] 2+ , Cs + , and Sr 2+ 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.