Effects of binary mixed surfactants on the hydride transfer reaction of methylene blue and 2,5-dihydroxyl-1,4-benzoquinone in aqueous solution

The hydride transfer reaction between methylene blue (MB⁺) and 2,5-dihydroxyl-1,4-benzoquinone (BQ) in mixed surfactant solutions has been studied at 25°C using a stopped-flow spectrometer. The results indicate that the mixed surfactant systems of cationic or anionic with zwitterionic or nonionic surfactants (LSS/CTAB, LSS/TTAB, LSS/DTAB, LSS/SDS, Triton X-100/CTAB, Triton X-100/SDS, Brij35/CTAB, Brij35/TTAB, Brij35/DTAB, Brij35/SDS) have inhibition effects on the hydride transfer reactions, while a Brij35/TritonX-100 mixed surfactant system shows no appreciable effect. These effects are attributed to the effect of the electrostatic interactions and compared with that of single surfactants. Above the cmc of the mixed surfactant systems, the effects are treated quantitatively using a kinetic model.