Study of solubility of indicator dyes in aqueous solution of pure and binary mixed surfactants. Aggregation and microenvironmental properties of homo and hetero-micelles of triton X 100 and sodium dodecyl sulphate

Aggregation and microenvironmental properties of homo-and hetero-micelles of triton X 100 (TX 100) and sodium dodecyl sulphate (SDS) have been studied by monitoring the solubility of indicator dyes in aqueous surfactant solution. A method has been proposed for the determination of critical micelle concentration (cmc) of surfactant, the molar based distribution coefficient (K) of the solute between the micellar and the aqueous phase and the solubility in the micellar medium (Sm). Hildebrand solubility parameter (δH2) for the micelle-water interfacial region has been estimated from the value of log Sm for the homomicelles. Nonlinear variation of log Sm and log K with molefraction of a component surfactant of the binary mixture, SDS + TX 100 has been observed indicating nonideal mixing behaviour of the surfactants in the micelles.