Diffusion coefficients for the ternary system Ca(OH)2–H3PO4–water
Abstract
A conductimetric method has been used to measure the ternary diffusion coefficients of calcium hydroxide–phosphoric acid in dilute aqueous solution at 25 °C. Diffusion coefficients for concentrated solutions of the electrolytes are evaluated from previously reported Gouy optical data for the related system Ca(H2PO4)2–H3PO4–water. The experimental results indicate strong electrostatic coupling between diffusive flows of aqueous Ca(OH)2 and H3PO4. The implications for dissolution of calcium hydroxyapatite, the main constituent of bone and teeth, are discussed.