Functionalization of hydroxyapatite derived from cockle (Anadara granosa) shells into hydroxyapatite–nano TiO2 for photocatalytic degradation of methyl violet

Photocatalyst of hydroxyapatite–nano TiO2 (HAp-nTiO2) was prepared from phosphatation of calcined cockle (Anadara granosa) shells followed by dispersion of nano TiO2 powder into HAp precipitate and calcination at 400 °C for 2 h. The prepared material was characterized using X-ray diffraction, scanning electron microscope–energy dispersive X-ray spectrophotometry, gas sorption analysis, and UV-Vis diffuse reflectance spectrophotometry. The photocatalytic activity of the material was evaluated for methyl violet degradation over photocatalysis and photooxidation mechanism. The results showed that the homogeneous dispersion of TiO2 in the HAp-nTiO2 composite was achieved, as seen in the X-ray diffraction analysis, diffuse reflectance UV-Vis, and gas sorption analyses. The physicochemical and photocatalytic character of the composite exhibited the positive role of HAp as TiO2 support in enhancing the photocatalytic activity with a higher turnover number and reusability property than that of pure TiO2. It was also noted that the HAp-nTiO2 composite demonstrated rapid methyl violet degradation over photooxidation rather than by photocatalytic mechanism.

Photocatalytic mineralisation of herbicide 2,4,5-trichlorophenoxyacetic acid: enhanced performance by triple junction Cu–TiO2–Cu2O and the underlying reaction mechanism

A novel Cu–TiO2–Cu2O triple junction shows superior photocatalytic activity towards the degradation of toxic 2,4,5-trichlorophenoxyacetic acid herbicide, via a hole-dominant photooxidation mechanism.