Comparative study of the factors associated with the application of metal hexacyanoferrates for environmental Cs decontamination

Calcium alginate cohered beads of copper hexacyanoferrate (CuHCF), and iron hexacyanoferrate (FeHCF), were prepared and studied for their competence in the environmental Cs decontamination. The influence of temperature and solution pH, parameters which are crucial for effective decontamination are studied in detail. Kinetic study performed at varying temperatures showed that adsorption of Cs onto CuHCF is faster than on FeHCF, the difference observed mainly due to the difference in the adsorption capacities of the materials. Additionally, an important environmental issue, which is often omitted, the possibility of release of the ferrocyanide ion into the effluent solution, is discussed in detail. The concentration of total cyanide in the effluent solution passed through FeHCF is comparatively very high beyond pH 4. In contrary, it is lower than in CuHCF passed solution at pH below 4. Based on these results, FeHCF is a good option in highly acidic solutions, and for weakly acidic to slightly alkaline pH, CuHCF is effective.