Study on preparing the absorbent of potassium nickel hexacyanoferrate (II) loaded zeolite for removal of cesium from radioactive waste solutions and followed method for stable solidification of spent composites

The selective adsorption and stable immobilization of radioactive cesium, K-Ni-hexacyanoferrate (II) loaded zeolite (FC-zeolite) prepared by impregnation / precipitation method were studied. The uptake equilibrium of Cs⁺ for composites FC-zeolite was attained within 8 h and estimated to be above 97% in Cs⁺ 100 mg/l solution at pH 4-10. Maximum ion exchange capacity of Cs⁺ ions (Q_max) for FC-zeoliteX was 112.5 and 69.7 mg/g in pure water and sea water, respectively. Those values for FC-zeolite A was 85.7 and 42.7 mg/g. Decontamination factor (DF) of FC-zeolite X for ¹³⁴Cs was 149.7 and 107.5 in pure water and sea water respectively. Study on synthesized zeolites (A and X) made of HUST was also conducted in similar manner. The values of Q_max were 98.6 and 39.9 mg/g for zeolite A, and 69.5 and 20.8 mg/g for zeolite X in pure water and sea water, respectively. Decontamination factor (DF) of zeolite A and X for ¹³⁴ Cs showed lower values. The spent CsFC-zeolite was solidificated in optimal experimental conditions: 5% Na₂B₄O₇ additives; calcination temperature at 900^oC for 2 h in air. Solid form was determined some of parameters: immobilization of Cs, compressive strength, volume reduction after calcination (%) and leaching rate of Cs⁺ ions in deionization water. (author)