Sepawa Congress
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PhD Veronika Yavrukova

Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria | “Smart Mechatronics, Eco- and Energy Saving Systems and Technologies”, Sofia 1164, Bulgaria

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Current lectures/posters

14.10.2026

16:25

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16:45

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Auditorium

Phase Diagrams of Sodium Linear Alkyl Benzene Sulfonate in Ionic and Nonionic Cosurfactant Solutions

EDC

| European Detergents Conference (EDC)

, “Synergistic Effects in Amphiphilic Systems”

PhD Veronika Yavrukova (Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria | “Smart Mechatronics, Eco- and Energy Saving Systems and Technologies”, Sofia 1164, Bulgaria)
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(available in the SOFW media library after the congress)

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Lecture Language: English

Sodium alkyl benzene sulfonate (NaLAS) is one of the most commonly used synthetic anionic surfactants. It is used as detergents, emulsifiers and wetting agents in many commercial products. The main disadvantages of NaLAS are: not very good biodegradability; easy precipitation in hard water and at low temperatures. One efficient way to increase the solubility of NaLAS is to incorporate the NaLAS molecules in mixed micelles with nonionic and/or ionic surfactants. This approach was applied in our previous works [1,2] for sulfonated methyl esters (Cn-MES), which is a good alternative to NaLAS in the formulations such as laundry detergents. The boundaries of the phase diagrams are experimentally obtained at a temperature of 5 °C by measuring the solubility limits at different concentrations of surfactants, the critical micelle concentrations, the electrolytic conductivity, etc.
The good theoretical description of the phase diagrams is achieved applying the extended thermodynamic model for the phase equilibrium. The model predicts the concentrations of all components (monomers, mixed micelles, precipitates if any), the composition of mixed micelles and their electrostatic potential. As a result, the phase diagrams at low temperatures of mixed NaLAS and other surfactant (nonionic and ionic) are compared to those of С16-MES, С18-MES and their mixtures in different ratios [1,2].
The proposed general model for describing the different phases in mixtures with nonionic and ionic surfactants is convenient for predicting such complex phase diagrams and can be used for optimization of formulations of practical interest.

[1] Danov K. et al. Journal of Colloid and Interface Science 601 (2021) 474–485. https://doi.org/10.1016/j.jcis.2021.05.147
[2] Yavrukova V.et al. Journal of Colloid and Interface Science 660 (2024) 896–906. https://doi.org/10.1016/j.jcis.2024.01.127

The authors are grateful for the financial support from the Project # KP-06-М89/2 – 04.12. 2024, with the National science fund of Bulgaria (abbreviated as BG FNI – MON).

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