抄録
Hydroxyapatite (HA) can be used for removing F−. Materials containing HA for removing F− can be obtained from biological wastes, and these HA might contain carbonate ions. The dissolution behavior of HA should affect the F− removal as fluorapatite (FA) formation at HA surface by the dissolution of HA and subsequent precipitation of FA results in the removal of F−. In this study, we examined the relationship between the dissolution and F− removal rates of carbonated HA (CHA). CHA samples with different carbonate contents were prepared by a hydrothermal process. The dissolution and F− removal rates were investigated by immersing the samples in pH 5 and 7 buffer solutions in the absence and presence of F−, respectively. The dissolution and F− removal rates were increased with an increase of carbonate-ion content in the samples. Dissolution and F− removal rates at pH 5 were larger than that at pH 7. The pseudo-second order kinetic model provides a good fit for the F− removal process. An increase in the kinetic constant of dissolution decreases the kinetic constant of the F− removal process for samples with high carbonate contents at pH 5.
