All-in-one treatment: Capture and immobilization of Cs by ultra-stable inorganic solid acid materials HMMoO·nHO (M = Ta, Nb).

Capture and immobilization of Cs is urgent for radioactive contamination remediation and spent fuel treatment. Herein, an effective all-in-one treatment method to simultaneously adsorb and immobilize Cs without high-temperature treatment is proposed. According to the strategy of incorporating high-valency metal ions into molybdates to increase the material stability and affinity towards radionuclides, layered HMMoO·nHO (M = Ta (1), Nb (2)) are prepared. Both materials exhibit excellent acid resistance (even 15 mol/L HNO). They maintain remarkable adsorption capacity for Cs in 1 mol/L HNO solutions and can selectively capture Cs under excessive competitive ions. Furthermore, they show successful cleanup for actual Cs-liquid-wastes generated during industrial production. In particular, adsorbed Cs can be firmly immobilized in interlayer spaces of materials due to the highly stable anionic framework. The removal mechanism is attributed to ion exchange between Cs and interlayer H by multiple characterizations. Study of the structure-function relationship shows that the occurrence of Cs ion exchange is closely related to plate-like layered structure. This work develops an efficient all-in-one treatment method for capturing and immobilizing radiocesium by ultra-stable inorganic solid acid materials with low energy consumption and high safety for radionuclide remediation.