Löslichkeit von Nickel-Zink-Ferriten in Säuren

Dissolution of zinc and nickel ferrites were previously found^2,3 to conform to the equations: $$\frac{{dx}}{{dt}} = ks_0 \left( {1 - x} \right)^3 K = \frac{1}{t}\left {\frac{1}{{\left( {1 - x} \right)^2 }} - 1} \right]$$ x-solubility (%),t=time (min),s ₀=initial specific surface (m ²·g^?1),k-rate constant independent of specific surface,K=apparent rate constant dependent on specific surface (min^?1). The aim of this work was to check the applicability of these equations to the dissolution of nickel—zinc ferrites. The experimental results obtained for 3 mixed ferrites (Ni_0.3Zn_0.7Fe₂O₄, Ni_0.5Zn_0.5Fe₂O₄, Ni_0.7Zn_0.3Fe₂O₄) revealed that kinetics of their dissolution in HCl, HNO₃ and their mixtures also conform to the equations stated above.