Effect of surfactant micelles on the redox reactions of cresyl violet

Reaction of hydrated electron with cresyl violet (CV) has been studied in different surfactant micelles using pulse radiolysis technique. This reaction, leading to the formation of transient semi-reduced species, slows down and the decay of the transient is considerably arrested in the micellar medium. Interactions of these surfactants have also been studied in both micellar and pre-micellar regions following the changes in absorption and emission characteristics of cresyl violet. Among the various surfactants investigated, anionic surfactants, particularly sodium lauryl sulphate (SLS) and sodium dodecyl benzene sulfonate (SDDBS), show marked effect on these properties. At surfactant concentrations below and above the CMC, formation of dye-surfactant complex and micellization of CV are observed, respectively. The association constant, K_A, for the formation of the complex and the binding constant, K_B, for the micellization of the dye are determined using the method of iteration. The environment in terms of dielectric constant experienced by CV inside the surfactant micelles has been estimated. Results of other surfactants, namely, bis (2-ethylhexyl) sulfosuccinate Na salt (BSS), cetyl trimethyl ammonium bromide (CTAB) and Triton X-100 (TX-100) have also been presented.