Coprecipitation of Zinc with Hydroxyapatite

Abstract

The distribution behavior of zinc between aqueous solution phase and hydroxyapatile was studied, where solid phase was prepared by adding hydrogenphosphate ion very slowly to an aqueous solution having calcium, trace zinc and ethylenediamine at 80°C. Apparent distribution coefficient remarkably decreased as the increase of ethylenediamine which .was used as a chelating agent of zinc and a buffering agent. The true distribution coefficient, K⁰, was calculated by using the thermodynamic data at 80°C and its value was about 10^5.5. The distribution coefficient kept constant in the range of less than 10^-5M of initial zinc concentration, while the coefficient gradually decreased as the zinc concentration increased over 10^-5M.