Photolytic color bleaching of cationic dyes in presence of selenious acid in aqueous and micellar environments

Photodecolorization of three cationic dyes in aqueous and micellar solution are reported under UV illumination in presence of selenious acid. Selenious acid (H2SeO3) has been used for the first time as a reagent for dye decolorization reaction. Micellar media have been found to influence the rate of decolorization reaction through electrostatic, hydrophobic and charge transfer interaction. It has also been shown that strong charge transfer and electrostatic interaction lead to an appreciable enhancement of the reaction rate in micelle, whereas, weak hydrophobic interaction is of marginal importance. In depth kinetic studies have been carried out to realize the interaction of the dyes with selenious acid and micelles. Kinetic studies have revealed that the reaction is first order with respect to H2SeO3 and zero order with respect to dye. ‘Salting-in’ and ‘salting-out’ agents were successfully employed for the real time application of the dye decolorization process.