Decontamination of very dilute Cs in seawater by a coagulation-precipitation method using a nanoparticle slurry of copper hexacyanoferrate

We examined the highly selective Cs adsorption ability of a potassium copper hexacyanoferrate (KCuHCF) slurry ink in seawater, i.e. very low Cs concentration in the presence of Na + , K + , Mg 2+ , Ca 2+ , and Cl − ions at high concentrations. The rational synthesis of the KCuHCF nanoparticle (KCuHCF-NPs, A y Cu[Fe(CN) 6 ] 1− x · z H 2 O) slurry ink was carried out using a Y-type micro-mixer and the composition dependence of the Cs-adsorption behavior was investigated. When a solution-to-adsorbent ratio of 10 000 mL g −1 was applied, batch experiments revealed that the Cs adsorption equilibrium was achieved within 10 min, with removal efficiency reaching as high as 99% of the Cs present (initial concentration is 10 μg L −1 ) and a distribution coefficient ( K d ) as high as 10 6 , even in the presence of competing alkali metal cations in seawater at high concentrations. For practical use, large flocs of the KCuHCF-NPs could be immediately coagulated after Cs adsorption using a high molecular-weight ionic polymer as a coagulant, along with regular Fe 2+ inorganic flocculants at the pH of seawater. We examined the highly selective Cs adsorption ability of a potassium copper hexacyanoferrate (KCuHCF) nanoparticle slurry ink in seawater, i.e. very low Cs concentration in the presence of Na + , K + , Mg 2+ , Ca 2+ , and Cl − ions at high concentrations.