Abstract
Titanium cation was introduced into calcium hydroxyapatite by three different procedures; (A) stepwise precipitation, (B) coprecipitation, and (C) surface treatment with aqueous titanium. The solids (Ti-CaHAp) thus obtained were employed as a photo-catalyst for the decomposition of methylene blue. No photo-catalytic activities were observed on Ti-CaHAp obtained from the surface treatment. Although rather great photo-catalytic activities have been already reported on Ti-CaHAp prepared with the stepwise precipitation, the decomposition of methylene blue on Ti-CaHAp depended on the atomic ratio of Ti/Ca in the catalysts. The photo-catalytic activities on Ti-CaHAp obtained from the coprecipitation were evidently greater that those on the solids obtained with the stepwise precipitation.
