Synthesis and performance of a photocatalytic titania-hydroxyapatite composite

摘要

The photocatalytic degradation of methylene blue (MB) over a porous titania-hydroxyapatite (HAp) composite under' ultraviolet radiation was studied. The catalyst was prepared by coating porous HAp with a titanium butoxide [Ti(OBu)_4] sol at titania loadings of 17-49 wt%. Quantitative powder x-ray diffraction showed higher proportions of anatase as the calcination temperature increased from 500 to 800 ℃ due to crystallization of an amorphous precursor. The transformation of anatase to rutile was delayed until 900 ℃, demonstrating the high thermal stability of the composite. Decomposition of HAp to a- and β- tricalcium phosphates takes place at 900 ℃ and is accompanied by the formation of perovskite at 1000 ℃. A systematic study of the influence of calcination temperature and titania:HAp ratios demonstrated that for the optimal material, a surface area of 100 m~2 g~(-1) was obtained at a titania loading of 49 wt% and calcination temperature of 600 ℃. A highly dispersed suspension of finely ground titania-HAp enhanced the photodegradation of MB, allowed a high percentage recovery of catalyst, and was shown to be recyclable.