The results of a kinetic study of the bleaching of the photostable dye rhodamine 6G by dissolved oxygen, photosensitized by TiO2, are reported. The observed variations in the initial rate of dye photobleaching as a function of the O2 percentage, temperature, incident light intensity and concentrations of rhodamine 6G and sacrificial electron donor are described and the results are rationalized using a proposed photochemical reaction scheme. The photosensitized bleaching of rhodamine 6G dye by TiO2 has a formal quantum yield of 2.65 X 10(-3), but the rate of complete photomineralization is about twofold slower. The overall activation energy for the semiconductor-sensitized dye photobleaching process is 15.0 +/- 1.5 kJ mol-1.
|Number of pages||9|
|Journal||Journal of Photochemistry and Photobiology A: Chemistry|
|Publication status||Published - 1994|