Abstract
Abstract Magnesium–calcium hydroxyapatite solid solution (MgCaHap) particles with different atomic Mg/(Mg + Ca) ratios ( X Mg ) from 0 to 0.28 were prepared by a wet method and were used as a cation-exchanger with Cd 2+ ions in solution by batch and flow methods. The amounts of Mg 2+ and Ca 2+ ions released into the solution from the particles and that of Cd 2+ ions incorporated into the particles from the solution were determined by the batch method. The ion-exchange with Cd 2+ reached an equilibrium within ca. 30 min and did not change the morphology and crystal structure of MgCaHap particles. The exchanged amount per gram exhibited a maximum at X Mg = 0.20 depending on the specific surface area of the particles. X Mg value of the MgCaHap particles after the ion-exchange treatment was less than that before the treatment, that is, Mg 2+ ions were more easily released from the MgCaHap particles than Ca 2+ ions by the treatment. The ion-exchange heat per gram and per mole of exchanged ions obtained by the flow method were increased with an increase of X Mg , indicating that the ion-exchange heat between Mg 2+ and Cd 2+ is more than that between Ca 2+ and Cd 2+ .
Published Version
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