Influence of the Concentrations of Potassium, Sodium, and Ammonium Ions on the Cesium Sorption with Mixed Nickel Potassium Ferrocyanide Sorbent Based on Hydrated Titanium Dioxide

摘要

The effect of single-charged cations (Na~+, K~+, NH_4~+) on the cesium sorption with mixed nickel potassium ferrocyanide sorbent based on hydrated TiO_2 was studied. The K~+ and Na~+ ions exert no effect at their concentrations of up to 0.5 M; the Cs~+ distribution coefficients from KCl and NaCl solutions are (1.1 ± 0.5) × 10~5 and (8 ± 3) × 10~4 mL g~(-1), respectively. The sorbent is highly specific to Cs~+ in the presence of ammonium ions. The sorption mechanisms were studied. The concentration ranges in which Cs~+ and NH_4~+ are sorbed by independent mechanisms (Cs~+, by the ferrocyanide phase; NH_4~+, by the phase of hydrated TiO_2) and in which the Cs~+ distribution coefficient decreases owing to competitive filling of the ferrocyanide phase with ammonium ions were determined. At cesium concentrations in solution exceeding 50 mg L~(-1), Cs~+ and NH_4~+ are absorbed jointly owing to coprecipitation in the mixed ferrocyanide phase in the pore space of the sorbent.