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

摘要

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+, Mg2+, Ca2+, and Cl- ions at high concentrations. The rational synthesis of the KCuHCF nanoparticle (KCuHCF-NPs, A(y)Cu[Fe(CN)(6)](1-x)center dot zH(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 mu g 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 Fe2+ inorganic flocculants at the pH of seawater.