Spectrophotometric investigation of the interactions between cationic dye (C.I. Basic Yellow 2) and anionic surfactant (sodium dioctylsulfosuccinate) in the premicellar and micellar region

The interactions between C.I. Basic Yellow 2 (BY2) and sodium dioctylsulfosuccinate (NaDS) have been investigated in the premicellar and micellar region using spectrophotometric method at 288.15, 298.15, 308.15 and 318.15 K. Absorption spectra of dye–surfactant mixtures show that dye–surfactant aggregates occur in the premicellar region. The addition of excess NaDS to the BY2 solution enhances the solubility of dye molecules due to the micelle formation. Moreover, the presence of excess surfactant micelles in the dye solution causes an increase in the absorption intensity of BY2 and leads to a bathochromic shift in the maximum absorption wavelength of dye. The values of binding constants, partition coefficients between the micellar and the bulk water phases and thermodynamic parameters have been calculated for the BY2–NaDS system at different temperatures. The binding of BY2 to surfactant micelles decreases with increasing temperature. The binding and partition processes are exothermic and occur spontaneously.

► Investigation of cationic dye–anionic surfactant interactions by spectrophotometric method at different temperatures.
► Following the spectra changes of dye–surfactant mixtures as a function of surfactant concentration and temperature.
► Determination of binding constants, partition coefficients and thermodynamic parameters.
► Finding that the binding and partition processes for the BY2–NaDS system take place spontaneously.
► Determination of binding and partition processes for the BY2–NaDS system as exothermic processes.