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

Authors: 

Tulasi Prasad Niraula, Renu Shah, Dileep Kumar, Hector Dominguez, Marlene Ríos-López, Ana Beatriz Salazar-Arriaga, Ranjit De, Ajaya Bhattarai

Source title: 
Journal of Molecular Liquids, 349: 118186, 2022 (ISI)
Academic year of acceptance: 
2021-2022
Abstract: 

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 a was assessed. The negative values of a 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 a 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.