Interaction of metanil yellow dye with cationic surfactants: Conductometric and spectroscopic studies

Conductometric and spectroscopic methods were used to examine the interactions among the cationic surfactants, tetradecyltrimethylammonium bromide (TTAB) and cetylpyridinium chloride (CPC), and the anionic azo dye metanil yellow (MY) in an aqueous solution. The standard Gibb's energy (Delta G0m), enthalpy (Delta H0m), and entropy (Delta S0m) of micellization were determined with the help of the equilibrium model. With temperature rise, the critical micelle concentration (cmc) increases because of the interrup-tion of the organized water (WR) molecules enclosing the surfactant's hydrophobic groups. As the total carbon atoms of the hydrophobic group are more in CPC than TTAB, a considerable fall in cmc value was observed. The presence of MY caused a higher degree of ionization (a) of micelles of TTAB and CPC. The negative values of Delta G0m and Delta H0m for both the surfactants in WR and aqueous MY solution (WR-MY) show that the micellization process is spontaneous and exothermic. As indicated by the -T Delta S0m values, which were found to be greater than Delta H0m values, the entropy gain is typically what regulates the micellization process and the micellization was found to have a negative heat capacity (Delta C0p;m). UV-Visible spectra show that CPC has a higher binding constant (Kb) value as compared to TTAB implying that CPC has a comparatively greater binding affinity with MY dye in aqueous media (WR). The decreasing value of Delta Gb for CPC indicates that the chance for the MY-CPC complex formation is more than that of the MY-TTAB complex. As shown by the rise in absorbance values as surfactant concentrations increase, a large number of the MY molecules are attracted to TTAB and CPC micelles.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Conductometric and spectroscopic methods were used to investigate the interactions between cationic surfactants and anionic dyes in an aqueous solution. The study found that the critical micelle concentration increased with temperature and decreased with a higher number of carbon atoms in the hydrophobic group of surfactants. The presence of the dye led to a higher degree of ionization of the surfactant micelles. The micellization process was determined to be spontaneous and exothermic, with entropy gain playing a crucial role. UV-Visible spectra showed a higher binding affinity between a specific surfactant and the dye. Increasing surfactant concentrations attracted a larger amount of dye molecules into the micelles.