Competitive solubilization of Sudan IV and anthracene in micellar systems

Abstract

Single solubilization of Sudan IV and anthracene has been studied in aqueous surfactant systems of sodium dodecyl sulphate, cetyltrimethylammonium bromide and Triton X-100 at 30°C by a spectrophotometric technique. Sudan IV was found to be more highly solubilized in micellar solutions than anthracene. Solubilization of Sudan IV and anthracene in the presence of each other was also studied in the surfactant systems. It was found that Sudan IV is preferentially solubilized over anthracene when solubilized jointly. This is reflected in the calculated values of the number of moles of surfactant solubilizing 1 mol of dye, the free energy change and the number of molecules of dye solubilized in a micelle. From the successive solubilization studies of Sudan IV and anthracene it has been found that the absorbance of one solubilizate does not change after the addition of the second solubilizate. The solubilization behaviour of dyes was discussed with respect to the aggregation number, occupancy of different solubilization sites and the chemical nature of the two dyes.