Highly Efficient Hybrid Sorbent for Simultaneous Removal of Radioactive Cesium and Iodine

Radioactive cesium (Cs) and iodine (I) are considered as emerging issues because of their high radiotoxicity and solubility so that the released Cs and I to the surrounding environemnts may cause the serious problem. Because Cs and I exsit in aqueous conditions like Cs⁺ and I^-/IO₃^-, respectively, ion-exchange of sorbent cannot remove both cationic and anionic radionuclides from the waste solution at the same time. Layered double hydroxide (LDH) and bentonite have good anion and cation exchange capacities and they are expected as the promising sorbents for removal of I and Cs, respectively. However, singly LDH or bentonite sorbent can't be used to treat both cationic and anionic contaminants simultaneously. In this study, based on the advantages of both prussian blue (PB) and layered double hydroxide (LDH), prussian blue functionalized-layered double hydroxide (PB-LDH) was developed to concurrently remove both Cs⁺ and IO₃⁻ from solutions. In addition, the functionalization of CuAlBi LDH on bentonite (CuAlBi LDH@Ben) was synthesized to remove both Cs and I from waste solutions. During the synthesis of PB-LDH, Fe(CN)₆⁴⁻ aggregated on the LDH surface according to electrostatic force to form the PB on the surface of LDH. The synthesized PB-LDH simultaneously removed 32 mg/g of Cs⁺ and 91 mg/g of IO₃⁻ from the mixed waste solutions. CuAlBi LDH on bentonite (CuAlBi LDH@Ben) also revealed an effective approach for removing both cesium and iodine from aqueous solutions, exhibiting K_d values of 1943.1 mL/g of Cs⁺, 442.4 mL/g of I^-, and 650.7 mL/g of IO₃^-, respectively. These hybrid sorbents can be used to remove both cationic and anionic radionuclides from the waste streams at the same time with reducing the costs.