Journal of Surface Science and Technology

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Interfacial and Thermodynamic Properties of Mixed Anionic-Nonionic Binary Surfactant system


Affiliations
1 Department of Chemistry, M. S. University of Baroda, Baroda 390 002, India
2 Research and Development Centre, Indian Petrochemicals Corporation Limited, Baroda 391 346, India
     

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The interfacial and thermodynamic properties of sodium dodecyl benzene sulfonate (SDBS) and polyoxyethylene-10-dodecylether mixed surfactant systems in aqueous solutions were studied. The critical micelle concentration (CMC) and the degree of ionization (α) for all the systems were computed at 35, 40, 45 and 50°C, by both surface tension and conductivity measurements. The standard free energy (ΔG0m), enthalpy (ΔH0m) and entropy (ΔS0m) of micellization were evaluated. An enthalpy-entropy compensation was observed. Gibbs adsorption equation was used to compute surface excess concentration (Γmax) and hence minimum area per molecule (Amin). Surface pressure at CMC (ΠcMc) was also computed. The thermodynamic quantities of adsorption of the surfactants at the air/water interface were evaluated. Interaction between the surfactant molecules in the mixed monolayers (βσ) and mixed micelles (βm) were calculated from the regular solution approach. Viscosities of surfactant solutions were determined and the viscosity activation parameters were calculated.
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  • Interfacial and Thermodynamic Properties of Mixed Anionic-Nonionic Binary Surfactant system

Abstract Views: 190  |  PDF Views: 2

Authors

S. B. Sulthana
Department of Chemistry, M. S. University of Baroda, Baroda 390 002, India
S. G. T. Bhat
Research and Development Centre, Indian Petrochemicals Corporation Limited, Baroda 391 346, India
A. K. Rakshit
Department of Chemistry, M. S. University of Baroda, Baroda 390 002, India

Abstract


The interfacial and thermodynamic properties of sodium dodecyl benzene sulfonate (SDBS) and polyoxyethylene-10-dodecylether mixed surfactant systems in aqueous solutions were studied. The critical micelle concentration (CMC) and the degree of ionization (α) for all the systems were computed at 35, 40, 45 and 50°C, by both surface tension and conductivity measurements. The standard free energy (ΔG0m), enthalpy (ΔH0m) and entropy (ΔS0m) of micellization were evaluated. An enthalpy-entropy compensation was observed. Gibbs adsorption equation was used to compute surface excess concentration (Γmax) and hence minimum area per molecule (Amin). Surface pressure at CMC (ΠcMc) was also computed. The thermodynamic quantities of adsorption of the surfactants at the air/water interface were evaluated. Interaction between the surfactant molecules in the mixed monolayers (βσ) and mixed micelles (βm) were calculated from the regular solution approach. Viscosities of surfactant solutions were determined and the viscosity activation parameters were calculated.