COADSORPTION OF CATIONIC DYES WITH SURFACTANTS ON COLLOIDAL TIO2 PARTICLES TO ACHIEVE PHOTOSENSITIZATION IN HIGHLY ACIDIC MEDIA

Absorption and emission characteristics of rhodamine B (RB) were inves tigated in aqueous solutions of sodium dodecylbenzenesulfonate (DBS) a t pH 0.9 in the absence and presence of colloidal TiO2. From the spect ral changes one can obtain detailed information about the interaction between RB, DBS and TiO2. No adsorption of RB onto the surface of TiO2 occurred at the quite low pH due to the strong electrostatic repulsio n between RB molecules and the positively charged TiO2 particles. Addi tion of DBS was found to be capable of improving the coadsorption of R B onto the surface of TiO2 particles, and thus realizing and efficient charge injection from the excited state of RB into the conduction ban d of TiO2.