42 巻 (2017) 6 号 p. 167-171
We report the synthesis of a photocatalytic composite of spherical porous hydroxyapatite (sHAp) and TiO2. sHAp was prepared by a wet method using simulated body fluid as a slurry and was then mixed with a TiO2 sol to obtain the sHAp + TiO2 composite. The TiO2 content of sHAp + TiO2 was ~7.8 wt. %. sHAp+TiO2 showed photocatalytic activity that was more than ten times greater than that of TiO2 even under irradiation with the low-intensity ultraviolet (UV) light of a fluorescent lamp. Mb decomposition of 58.2% was achieved under UV light with an intensity of 7.60 ×102 μW cm-2 using the sHAp + TiO2 composite, which is significantly higher than the 8.05% achieved using only TiO2. Thus, the composite material showed higher activity than that of unsupported TiO2. Furthermore, sHAp + TiO2 could oxidize leucocrystal violet (LCV) to crystal violet (CV) even after being placed in the dark for 120 h. The positively charged holes are suggested to persist on TiO2 because of the electron withdrawing effects of sHAp and can contribute to LCV oxidation. Thus, the photocatalytic activity of TiO2 was improved by using sHAp as a support.