Partitioning of reactive yellow 86 between aqueous and micellar media studied by differential absorption spectroscopy

The present study describes the partitioning of a reactive dye, reactive yellow 86, between aqueous and micellar media of a cationic surfactant (cetyltrimethyl ammonium bromide, CTAB), as well as an anionic surfactant (sodium dodecyl sulphate, SDS). In a systematic investigation, we have recorded the UV-vis absorption spectra of the dye as a function of surfactant's concentration above and below the critical micelle concentration (CMC). Absorption spectra display a red shift in the case of CTAB and a hypochromic shift upon using SDS. The partition coefficient (K_x) was calculated using differential absorption data, and the value of free energy of partition (G_p) was calculated using this K_x value. The results revealed that the dye is solubilized in CTAB micelles to a greater extent than in SDS micelles.