Decontamination of radioactive cesium-contaminated soil/concrete with washing and washing supernatant– critical review.

We reviewed washing of radioactive Cs-contaminated concrete and soil based on the fate of Cs in concrete and soil, including sorption materials for treatment of supernatant solution. In non-aged cement materials (the calcium silicate hydration (C–S–H) phase), it was possible to decontaminate Cs using ion exchange with monovalent cations, such as NH 4 +. The clay components in the soil and aggregates were important factors in optimization of the efficiency and mechanism for Cs decontamination with washing solution. The parameters (reagent component, pH, and temperature) of the washing solution should be determined considering soil mineral type (here, weathered biotite (WB) with vermiculite), since monovalent cations such as NH 4 + and K+ can inhibit Cs decontamination due to collapse of the hydrated and expanded interlayer regions with cation exchange. In this case, hydrothermal treatment or H 2 O 2 dosing was necessary to expand the collapsed interlayer region for Cs removal by washing with cation exchange or organic acids. Acid and a chelating agent significantly enhanced Cs-release with dissolution of the adsorbent layer containing iron and aluminum oxides. The important characteristics of important and emerging sorption materials for treatment of the radioactive Cs-contaminated supernatant after washing treatment are discussed. Sorbents for treatment of washing supernatant are divided in to two main categories. Clay minerals, metal hexacyanoferrates, and ammonium molybdophosphates are discussed in the inorganic class of materials. Hypercrosslinked polymers, supramolecular sorbents, carbon nanotubes, and graphene oxide are covered in the carbon–based sorbents for Cs removal from water. • Ion exchange with monovalent cation is major mechanism for Cs decontamination. • Clay components in the soil and aggregates are important factor for Cs decontamination. • Interlayer expansion of clays was required for ion exchange of Cs with cations. • Cs adsorbents are classified as inorganic and organic adsorbent. • Cs selectivity of adsorbent in washing supernatant should be considered. [ABSTRACT FROM AUTHOR]