Mixed-micellar approach for enhanced dye entrapment: A spectroscopic study

Abstract

The interactional study of two anionic dyes viz. Reactive Blue-250 and Reactive Red-198 in the presence of single cationic surfactant and mixed-surfactant media is reported in this manuscript. To unveil the dye-surfactant interactions, a cationic surfactant Cetyltrimethylammonium bromide (CTAB) and its mixture with a nonionic surfactant Triton X-100 (TX), were used. The interactions were investigated using UV–Visible spectroscopy in sub-micellar, micellar, and post-micellar concentrations. The extent of solubilization in terms of partition constant (Kc), partition coefficient (Kx), binding constant (Kb), Gibbs free energies (ΔGp and ΔGb), and the approximate location of dye molecules in the micelles was assessed from spectroscopic measurements. The mixing of nonionic/cationic surfactants in appropriate amounts enhanced the solubilization of both reactive dyes. The experimental results revealed the spontaneous nature of solubilization and the dye-surfactant aggregates in single and mixed-surfactant media were stable. The synergism of cationic surfactant with nonionic counterpart is favorable to attain deep entrapment in the micelles than the single cationic surfactant. This method may provide inexpensive, highly efficient, and time-saving procedures in the removal of dyes from water resources.