Surface Adsorption in Ternary Surfactant Mixtures above the Critical Micelle Concentration: Effects of Asymmetry on the Composition Dependence of the Excess Free Energy

Abstract

The composition of the adsorbed layer of a ternary surfactant mixture at the air-water interface has been studied by neutron reflectivity. The adsorption of the ternary mixture of octaethylene monododecyl ether (CE) sodium dodecyl 6-benzene sulfonate (LAS), and sodium dioxyethylene glycol monododecyl sulfate (SLES), as well as each of the binary mixtures, at solution concentrations greater than the mixed critical micelle concentration is highly nonideal. In the ternary mixture, the surface adsorption is dominated by CE and LAS, and there is little SLES at the interface. The departure from ideality in the binary mixtures can be quantitatively described by applying the pseudophase approximation with quadratic and cubic terms in the excess free energy of mixing (G) both at the surface and in the micelles. The same parameters that describe the binary interactions give a quantitative fit to the adsorbed fractions in the ternary mixture over a wide range of composition. A similar analysis is effective for the mixture containing sodium dodecyl sulfate instead of SLES. Of the set of six G required to fit the ternary data, one is ideal (SLES-LAS) and three, LAS-CE (micelle) and CE-SLES (micelle and surface), have minima occurring at a composition (mole fraction) of the anionic species of 1/3.

Wettability Alteration and Adsorption of Mixed Nonionic and Anionic Surfactants on Carbonates

“…The role of surfactants in mixed micellization as well as adsorption has been studied for different surfactant mixtures, such as nonionic/nonionic, − ionic/ionic, − nonionic/anionic, − and nonionic/gemini − surfactants. In terms of ionic and nonionic surfactant mixtures, the system comprising of sodium dodecyl sulfate and polyoxyethylene ethers has been the most widely investigated one. − These studies used different combinations of nuclear magnetic resonance (NMR), electron paramagnetic resonance, small-angle neutron scattering, and light scattering to investigate the mixed micellization behavior in these mixtures.…”

Bacillus licheniformis SMIA-2 protease used as an additive in detergent formulations

“…Protease displayed good stability when incubated in the presence of 0.75% (w/v) LAS for 2 hours, at 45ºC. LAS is an anionic surfactant that plays a significant role in modern cleaning products, due to its efficiency in removing dirt (Liley et al, 2017;Cornwell, Radford, Ashcroft, & Ault, 2018). The protease (namely SAPB) from Bacillus pumilus strain CBS I 52 exhibited high stability against strong anionic surfactants, particularly sodium dodecyl sulphate (SDS) and LAS (Jaouadi, Ellouz-Chaabouni, Rhimi, & Bejar, 2008).…”

Co-solvent Effect on Spontaneous Formation of Large Nanoscale Structures in Catanionic Mixtures in the Anionic-Rich Region

“…Using a model (developed by Rubingh et al [29][30][31]), as a regular solution for determination of β parameters in binary systems, gives us an evaluation of the nature and strength of the interactions between two surfactants. The following equations were used to calculate the β M interaction parameter for mixed micelle in our aqueous medium [32]:…”

“…Journal of Solution Chemistry (2020) 49:[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] …”