Effect of Ca 2+ /Mg 2+ on the stability of the foam system stabilized by an anionic surfactant: A molecular dynamics study

Li, Chunling; Zhang, Tiantian; Ji, Xianjing; Wang, Zhikun; Sun, Su-Qin; Hu, Songqing

doi:10.1016/j.colsurfa.2015.11.012

Cited by 53 publications

(22 citation statements)

References 55 publications

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“…In recent years, an increasing number of researchers have employed computational methods to investigate the phase behaviors of surfactants, and polymers in the foam system, and their influences on the foam’s properties and stability. They have mainly focused on the structure and stability of the foam film stabilized by surfactants, − microscopic mechanism of the stabilizing foam by formulating anionic and zwitterionic surfactants, the impacts of inorganic cations on foam stability, , the synergistic effect of surfactants and polymers in the foam system, , and the microscopic mechanisms of foam destruction caused by crude oil . In those studies, SDS has also been used to study the foam stability. ,,, Hu et al and Jang and Goddard compared the adsorption behavior of SDS and other surfactants at the vacuum/water interface by using molecular dynamics (MD) simulations and discussed their impacts on foam film stability.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study on CO₂ Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

et al. 2020

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CO2 foam flooding technology can be used for geological storage of greenhouse gas CO2 while enhancing oil recovery. In this paper, we performed molecular dynamics simulations for the CO2 foam film systems stabilized with an anionic surfactant of sodium dodecyl sulfate (SDS). Compared to other factors of a foam system, interfacial tension was used as the primary indicator to evaluate the stability of the SDS foam film. The effects of the concentration of the SDS surfactant, temperature, and pressure on the interfacial tension were studied. Based on the calculated results, the stability of the CO2 foam film was discussed. It is found that under the high-concentration condition, SDS molecules can form a dense and thick molecular layer at the interface, blocking the contact of CO2 molecules and water molecules and reducing the interfacial tension. Consequently, the stability of the foam liquid film can be improved. Low temperature and high pressure lead to high density of the CO2 phase, which enables strong interactions between CO2 and the hydrophobic tails of SDS molecules. The interfacial structure thus formed can reduce the contact probability between CO2 and water molecules, generating lower interfacial tension. Therefore, high SDS concentration, low temperature, and high pressure are beneficial to the stability of the CO2 foam. We show that the adsorption of CO2 molecules at the interface, the interfacial thickness, and solvent accessible surface area of the surfactant to the CO2 phase are affected by the density of CO2 bulk phase, which are important interfacial properties affecting the CO2/water interfacial tension and the stability of the CO2 foam.

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study on CO₂ Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

et al. 2020

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“…In the last two decades, MD simulations have been widely used to study the behavior of amphiphilic molecules in the bulk and at interfaces. The structure and dynamics of surfactant layers formed at the vacuum–water − and oil–water − interfaces is characterized using atomistic or coarse-grained , MD simulations. Almost all reported molecular models are constructed by fixing the surfactant molecules at the interface at predefined areas per molecule.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Origin of the Specificity of Calcium and Sodium Cations Binding to Adsorption Monolayers of Two Anionic Surfactants

2020

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The studied anionic surfactants linear alkyl benzene sulfonate (LAS) and sodium lauryl ether sulfate (SLES) are widely used key ingredients in many home and personal care products. These two surfactants are known to react very differently with multivalent counterions, including Ca2+. This is explained by a stronger interaction of the calcium cation with the LAS molecules, compared to SLES. The molecular origin of this difference in the interactions remains unclear. In the current study, we conduct classical atomistic molecular dynamics simulations to compare the ion interactions with the adsorption layers of these two surfactants, formed at the vacuum–water interface. Trajectories of 150 ns are generated to characterize the adsorption layer structure and the binding of Na+ and Ca2+ ions. We found that both surfactants behave similarly in the presence of Na+ ions. However, when Ca2+ is added, Na+ ions are completely displaced from the surface with adsorbed LAS molecules, while this displacement occurs only partially for SLES. The simulations show that the preference of Ca2+ to the LAS molecules is due to a strong specific attraction with the sulfonate head-group, besides the electrostatic one. This specific attraction involves significant reduction of the hydration shells of the interacting calcium cation and sulfonate group, which couple directly and form surface clusters of LAS molecules, coordinated around the adsorbed Ca2+ ions. In contrast, SLES molecules do not exhibit such specific interaction because the hydration shell around the sulfate anion is more stable, due to the extra oxygen atom in the sulfate group, thus precluding substantial dehydration and direct coupling with any of the cations studied.

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“…Adding a chloride to surfactant solutions improved their surface activity and had a good effect on their adsorption at the liquid–air interface. On the other hand, many reports [ 65 , 88 , 89 , 90 , 91 , 92 ] indicate that this behavior of surfactants has a positive impact on foaming properties and foam stability in the minimum salt concentration range or just before the CMC of the system. Increased concentrations of salt in the system restrain the saturation of the adsorption layer between the liquid and the gas; this is caused by interactions between the surfactants and the cations originating from the salt and leads to the formation of smaller and less stable air bubbles.…”

Section: Resultsmentioning

confidence: 99%

Correlations between the Type of Aggregates in the Bulk Phase and the Functionality and Safety of All-Purpose Cleaners

Seweryn

Wasilewski

Bocho-Janiszewska

2021

IJMS

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The article shows that the type and concentration of inorganic salt can be translated into the structure of the bulk phase and the performance properties of ecological all-purpose cleaners (APC). A base APC formulation was developed. Thereafter, two types of salt (sodium chloride and magnesium chloride) were added at various concentrations to obtain different structures in the bulk phase. The salt addition resulted in the formation of spherical micelles and—upon addition of more electrolyte—of aggregates having a lamellar structure. The formulations had constant viscosities (ab. 500 mPa·s), comparable to those of commercial products. Essential physical-chemical and performance properties of the four formulations varying in salt types and concentrations were evaluated. It was found that the addition of magnesium salt resulted in more favorable characteristics due to the surface activity of the formulations, which translated into adequately high wettability of the investigated hydrophobic surfaces, and their ability to emulsify fat. A decreasing relationship was observed in foaming properties: higher salt concentrations lead to worse foaming properties and foam stability of the solutions. For the magnesium chloride composition, the effect was significantly more pronounced, as compared to the sodium chloride-based formulations. As far as safety of use is concerned, the formulations in which magnesium salt was used caused a much lesser irritation compared with the other investigated formulations. The zein value was observed to decrease with increasing concentrations of the given type of salt in the composition.

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Effect of Ca 2+ /Mg 2+ on the stability of the foam system stabilized by an anionic surfactant: A molecular dynamics study

Cited by 53 publications

References 55 publications

Molecular Dynamics Study on CO₂ Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

Molecular Dynamics Study on CO₂ Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

Revealing the Origin of the Specificity of Calcium and Sodium Cations Binding to Adsorption Monolayers of Two Anionic Surfactants

Correlations between the Type of Aggregates in the Bulk Phase and the Functionality and Safety of All-Purpose Cleaners

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Effect of Ca 2+ /Mg 2+ on the stability of the foam system stabilized by an anionic surfactant: A molecular dynamics study

Cited by 53 publications

References 55 publications

Molecular Dynamics Study on CO2 Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

Molecular Dynamics Study on CO2 Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

Revealing the Origin of the Specificity of Calcium and Sodium Cations Binding to Adsorption Monolayers of Two Anionic Surfactants

Correlations between the Type of Aggregates in the Bulk Phase and the Functionality and Safety of All-Purpose Cleaners

Contact Info

Product

Resources

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Molecular Dynamics Study on CO₂ Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension

Molecular Dynamics Study on CO₂ Foam Films with Sodium Dodecyl Sulfate: Effects of Surfactant Concentration, Temperature, and Pressure on the Interfacial Tension