A quantification of immersion of the adsorbed ionic surfactants at liquid|fluid interfaces

Shahir, Afshin Asadzadeh; Nguyen, Anh V.; Karakashev, Stoyan I.

doi:10.1016/j.colsurfa.2016.08.082

Cited by 7 publications

(17 citation statements)

References 33 publications

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“…Phan et al followed this approach and developed a model for non-ionic surfactants such as MIBC [132] and 1-hexanol [133], but they used an ionizing electrode to measure the surface potential. Surface excess, derived from the Gibbs isotherm, is also widely used to fit the adsorption models [134,135], but we did not find any paper using surface excess from neutron reflection or radiotracer results to fit adsorption models.…”

Section: Accepted Manuscript 50mentioning

confidence: 80%

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A critical review of the model fitting quality and parameter stability of equilibrium adsorption models

Peng

Nguyen

Wang

et al. 2018

Advances in Colloid and Interface Science

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We reviewed eight commonly used equilibrium adsorption models and examined their underlying assumptions, fitting qualities, and parameter stabilities. We compared several objective functions that have been applied to curve fitting analysis and a few statistics tests that have been performed to evaluate regression quality. The iteratively reweighted least squares algorithm was selected as the most suitable regression method for adsorption models in the presence of heteroscedasticity. The fraction of unexplained variance was selected to indicate the model fitting quality. Two sources of parameter instability were identified: residue instability and function instability. While the definition of the instability caused by residue is well established, we are the first to consider the instability caused by an adsorption model. The models discussed in this article can be applied to many surfactants, such as normal alcohols, polyglycol ethers, and sodium dodecyl sulfate at different salt concentrations. Our results show that both the model fitting quality and parameter instability increase with the number of parameters subject to curve fitting. For the Frumkin-type of reorientation model, the parameter instability can be as high as 25%. The high degree of instability in some complicated adsorption models may invalidate the estimated parameters.Therefore, additional measurements or simulations are required for complicated models to extract reliable model parameters.

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Section: Accepted Manuscript 50mentioning

confidence: 80%

“…Therefore, the discrepancies can only be explained by more realistic adsorption models, considering the density profile of surfactants and counterions. However, very few models [134,135] have considered this property of adsorbed surfactant layers.…”

Section: Accepted Manuscript 50mentioning

confidence: 99%

A critical review of the model fitting quality and parameter stability of equilibrium adsorption models

Peng

Nguyen

Wang

et al. 2018

Advances in Colloid and Interface Science

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“…[33] Shahir et al argue that at the oil/water interface,t he surfactant presence is 70 %l ower than that at the water/air interface,asaconsequence of stronger repulsion between the ionic SDS head groups at the oil/water interface. [34] Similarly, Fainerman et al emphasized that the competitive as well as cooperative adsorption between oil and surfactant molecules should be taken into account to provide agood description of the oil/water interface. [35] During the surfactant-induced ordering of MCT molecules,w ea ssume ac hange in area per MCT molecule from 150 2 (low ordered) to % 80 2 (fully ordered).…”

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confidence: 99%

Effect of Surfactants on the Molecular Structure of the Buried Oil/Water Interface

2021

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The oil/water interface,for instance in emulsions,is often stabilized by surfactants.H ence,t he co-existence of oil, water,and surfactant molecules at the buried oil/water interface determines macroscopic properties such as surface tension or emulsion stability.U tilizing an inherently surface sensitive spectroscopic method, sum frequency generation (SFG) spectroscopy, we showt hat adsorption of an anionic surfactant to the buried oil/water interface increases the magnitude of the interfacial electric field. Meanwhile,t he degree of ordering of the interfacial oil molecules increases with the surfactant concentration owing to the intercalation of aliphatic chains of interfacial oil and surfactant molecules.A ts ufficiently high surfactant concentrations,the interfacial charge reaches amaximum value and the interfacial oil molecules arrange in afully ordered conformation, as tate which coincides with the significant decrease in interfacial tension and increased emulsion stability.

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“…In this model, ionic surfactant SDS has a primary adsorption layer at the air−water interface and a secondary adsorption layer underneath the interface that is immersed in the water phase. 20 This model extends the twolayer model in Table 1 to four layers, including counterion adsorption layers for each surfactant adsorption layer. Briefly, the additional layer facilitates the adsorption of both surfactant and counterions and consequently reduces the surface tension more effectively.…”

Section: Comparison With Experimentsmentioning

confidence: 98%

From Surface Tension to Molecular Distribution: Modeling Surfactant Adsorption at the Air–Water Interface

et al. 2021

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Surfactants are centrally important in many scientific and engineering fields and are used for many purposes such as foaming agents and detergents. However, many challenges remain in providing a comprehensive understanding of their behavior. Here, we provide a brief historical overview of the study of surfactant adsorption at the air−water interface, followed by a discussion of some recent advances in this area from our group. The main focus is on incorporating an accurate description of the adsorption layer thickness of surfactant at the air−water interface. Surfactants have a wide distribution at the air−water interface, which can have a significant effect on important properties such as the surface excess, surface tension, and surface potential. We have developed a modified Poisson−Boltzmann (MPB) model to describe this effect, which we outline here. We also address the remaining challenges and future research directions in this area. We believe that experimental techniques, modeling, and simulation should be combined to form a holistic picture of surfactant adsorption at the air−water interface.

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A quantification of immersion of the adsorbed ionic surfactants at liquid|fluid interfaces

Cited by 7 publications

References 33 publications

A critical review of the model fitting quality and parameter stability of equilibrium adsorption models

A critical review of the model fitting quality and parameter stability of equilibrium adsorption models

Effect of Surfactants on the Molecular Structure of the Buried Oil/Water Interface

From Surface Tension to Molecular Distribution: Modeling Surfactant Adsorption at the Air–Water Interface

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