Chemical and thermal stability of potassium nickel hexacyanoferrate (II)

Abstract

The chemical and thermal stability of a nonstoichiometric compound K2-xNix/2[NiFe(CN)6]·nH2O (KNiFC) were examined in connection with distribution behavior for Cs+. The face-centered cubic (FCC) structure of KNiFC was stable even in the presence of 8M HCl or 8M HNO3, and the samples treated with acids had high Kd values for Cs+ above 104 cm3/g. This suggests high resistance of KNiFC to acids. For the KNiFC treated with HNO3, the lattice parameter (α) increased with increasing the concentration of HNO3 above 1M. The FCC structure decomposed with NaOH concentrations above 1M, probably due to the hydrolysis of constitutional elements. The thermal decomposition began above 250°C and several steps of weight loss, due to evolution of gases, were observed up to 1,000°C. © 1997 Taylor and Francis Group, LTD.