Spectrophotometric Study on the Mechanism of the Colour Change Reaction of Methylene Blue with Sodium Dodecyl Sulfate

Aiming to the cognition of the mechanism of the reaction between the molecules of methylene blue (MB) and the molecules of large-molecular compounds,the interaction of MB with sodium dodecyl sulfate (SDS) was studied spectrophotometrically.The effects of the presence of ethanol,sodium chloride,hydroxypropyl-β-cyclodextrin and Triton X-100 on the reaction were also tested.As shown by the experimental results,a complex compound was formed between MB and SDS leading to change of color,and the color-change reaction was affected obviously by the addition of ethanol.It was concluded that the complex-compound of MB-SDS was formed on the basis of electrostatic action,and the directional aggregation of MB molecules bound on the orderly aggregates of SDS was the cause the color change action.