Influence of solvent permittivity and divalent salt on micellization behavior of sodium dodecyl sulfate: Conductivity measurements and simulation study

• Published in: Journal of molecular liquids 2022-03, Vol.349, p.118186, Article 118186
• Main Authors: Niraula, Tulasi Prasad, Shah, Renu, Kumar, Dileep, Dominguez, Hector, Ríos-López, Marlene, Salazar-Arriaga, Ana Beatriz, De, Ranjit, Bhattarai, Ajaya
• Format: Article
• Language: English
• Subjects: CMC; Ethanol–water; SDS; Solvent parameters
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2021.118186

•On increasing ethanol, α and CMC increased whereas they decreased with addition of salt.•As amount of salt increases, we observe the more – ΔGm° which means system proceeds spontaneous.•Results from simulations of conductivity are in good agreement with experimental values. Precise conductivity measurements of sodium dodecyl sulfate (SDS) solutions with and without manganese sulfate in water and ethanol–water mixture containing (10, 20 and 30) volume % ethanol is carried out at 298.15 K. The conductance decreased on the addition of ethanol with and without salt. From the pre-micellar and post-micellar slopes, the degree of dissociation (α) of SDS was calculated. On increasing the ethanol content, the α and critical micelle concentration (CMC) increased whereas they decreased with the addition of salt. Utilizing these CMC and α values, the standard free energy of micellization (ΔGm°) was assessed. The negative values of ΔGm° decreased when ethanol whereas increased with salt were added. Micellization of SDS was tested for several solvent parameters and solvophobic parameter. The free energy of surfactant tail transfer (ΔGtrans°) was also evaluated. Conductivity data were also estimated with molecular dynamics simulations from GROMACS-5 software and the results showed good agreement with the experimental values.