Visible Light Induced Photodegradation of Capsicum Red Pigment by Tm/TiO2-Loaded Cotton

Cotton fabric loaded by Tm/TiO2 sol shows high photoactivity against capsicum oil under visible light. The X-ray diffraction spectra indicate that both anatase and rutile crystal sizes of Tm/TiO2 decrease with increase in Tm molar ratio (0-3%). The Tm/TiO2 optical absorption extends towards the visible spectrum and a red-shift of the maximum absorption edge (0.13eV) exists. Tm/TiO2-loaded cotton fabric exhibits higher photocatalytic activities than that loaded by pure TiO2 on the degradation of capsicum oil. The increase in photoactivity is probably due to the band-gap narrowing, interfacial charge transfer and the elimination of eletron-hole recombination. Fourier transform infrared (FT-IR) analysis demonstrates that the carbochain and carboxide carbonyls bonds in the capsanthin chain are broken and mineralized into CO2 and H2O by oxidation process. The whole process shows promise for the total removal of capsicum oil on the cotton fabric.