2015/07/04 by Germán Urbina-Villalba, German Urbina-Villalba, Neyda Garcia-Valera +5
Chemistry · Physics and Astronomy · #Electrostatics and Colloid Interactions #FOS: Physical sciences #Soft Condensed Matter (cond-mat.soft) #Spectroscopy and Quantum Chemical Studies #Surfactants and Colloidal Systems #cond-mat.soft
paper · pdf · doi:10.48550/arxiv.1507.01116
17 pages, 11 figures, RCEIF Vol. 4 (2015)
openalex publication_date 2015/07/04 · arxiv created 2015/07/07 · arxiv updated 2015/07/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Theoretical calculations of the mixed aggregation/coalescence (kFC) rate corresponding to a set of hexadecane-in-water nano-emulsions stabilized with sodium dodecyl sulphate (SDS) at different NaCl concentrations are presented. The rates were obtained through the change of the total number of aggregates of the dispersions as a function of time, predicted by Emulsion Stability Simulation (ESS). Two different models were implemented in order to mimic the dependence of the surface excess of the surfactant on the salt concentration. Experimental measurements of kFC were also made, based on the change of the turbidity of the emulsions as a function of time. A satisfactory agreement between theory and experiment is only attained if the model of surfactant adsorption accounts for the balance between the salting out of the surfactant solution and the partial screening of the surface charge of the drops induced by the increase of the ionic strength of the continuous phase. The observed behavior cannot be justified on the grounds of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Instead, the reversible flocculation of the aggregates of any size is proposed as an alternative mechanism to explain the dependence of kFC as a function of the salt concentration.