Encapsulation of ethyl violet by anionic-cationic mixed micellar solution: Spectroscopic and conductometric studies

Abstract

Organic dyes are extensively used in various industries i.e. textile. Their hydrophobicity is the main bottleneck in their applications, where the dispersion medium is water. The poor solubility of such colorants is addressed by the addition of different surfactants, but none of the single surfactants proved fully satisfactory so far. Herein, different formulations of anionic and cationic surfactants (SDS, SDBS, CTAB, and TTAB) have been employed to enhance the solubility and stability of a cationic dye, ethyl violet (EV). Spectrophotometric data helped to calculate the values of the partition coefficient (K x ), binding constant (K b ), and Gibbs energies of respective processes. The said parameters are indicators of the degree of solubilization which were calculated at 298.15 K. The data of specific conductance was utilized to estimate critical micelle concentration (CMC) and to calculate thermodynamic parameters; Gibbs energy (ΔG m ), entropy (ΔS m ), and enthalpy (ΔH m ) of micellization for surfactants in the presence of dye at different temperatures (303.15–318.15 K). The obtained results from both techniques revealed the spontaneous nature of micellization and solubilization. Furthermore, the binding and partitioning ability of mixed micellar media came out to be significantly different than that of the solo surfactant system due to the synergistic effect of cationics on micellar media of anionics. It shows how dye is lying inside the SDS and SDBS micelle. • Locus of incorporated dye is near water-micelle interface. • Charge density of a micelle governs its solubilizing efficacy. • Mixing of different surfactants has a synergistic effect on solubilizing power.