Publication Details (including relevant citation information):
Takeshi Moriguchi, Souhei Nakagawa:Phosphorus Research Bulletin, 26, 117-130 (2012).
Fe(III)-treated hydroxyapatites, HAP-300-Fe and HAP-400-Fe, were prepared from hydroxyapatites, HAP-300 (stoichiometric type) and HAP-400 (Ca-deficient type), respectively, and applied to photo-Fenton reaction of dyes as heterogeneous catalysts in comparison with other Fe catalysts such as Fe2O3, FePO4•2H2O, and FeOOH. Among the Fe catalysts, HAP-400-Fe revealed the highest consumption and mineralization in photo-Fenton reaction of alizarin red S (ARS), and also indicated good catalytic activity to other dyes, alizarin, neutral red, methyl red, methyl orange (MO), Congo red, and indigo carmine. Generation of hydroxyl radical •OH as an oxidation species from H2O2 was observed in the all Fe catalysts by an indirect method using N, N-dimethylamino-4-nitrosoaniline, which is exclusively sensitive to •OH. In order to elucidate catalysis mechanism of Fe catalysts, kinetic investigation based on Michaelis-Menten theory was conducted in the reaction of ARS and MO. As a result, HAP-400-Fe indicated high ability of bearing many dye molecules but low degradative catalysis ability to H2O2, compared with Fe2O3. However, judging from high mineralization ability as well as repeating availability (5 times), HAP-400-Fe is considered as an excellent heterogeneous catalyst for photo-Fenton reaction.