Effect of Water/Decane Ratios and Salt on the Stability, Rheology, and Interfacial Tension of Water/Decane Emulsions

Adewunmi, Ahmad A.; Kamal, Muhammad Shahzad

doi:10.1021/acs.energyfuels.9b02011

Cited by 20 publications

(8 citation statements)

References 42 publications

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“…2,21,22 On the contrary, some studies have shown an increase in emulsion stability with salt. 19,30,51,82,83 To explain these discrepancies, we considered three factors: the surfactant/oil ratio (S/O) or the interfacial area, the length scales of observation, and the timescales of observation.…”

Section: Resultsmentioning

confidence: 99%

“…It is important to explain our current observations that the addition of salt increased emulsion stability to coalescence, considering that this result is different from those of a majority of other emulsion stability studies. Many studies have shown that salt decreases the stability of oil-in-water emulsions stabilized by ionic surfactants, − non-ionic surfactants, , proteins, and in the absence of added surfactants. , The addition of salt to an emulsion has even been suggested as a method to help flocculate, coalesce, and remove oil from wastewater systems. ,, On the contrary, some studies have shown an increase in emulsion stability with salt. ,,,, To explain these discrepancies, we considered three factors: the surfactant/oil ratio (S/O) or the interfacial area, the length scales of observation, and the timescales of observation.…”

Section: Discussionmentioning

confidence: 99%

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Impact of Saltwater Environments on the Coalescence of Oil-in-Water Emulsions Stabilized by an Anionic Surfactant

et al. 2021

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The impact of salts on the stability of oil-in-water emulsions to coalescence was studied to aid in minimizing the impact of emulsified oils on natural water systems. Oil-in-water emulsions were fabricated from mineral oil, deionized water, and sodium lauryl ether sulfate. As salt (NaCl) concentrations increased from 0 to 1.25 M, an increase in emulsion stability to coalescence was observed over an aging period of 56 days. ζ potential and interfacial tension measurements showed that salt decreased the electrostatic repulsion of the anionic surfactant and allowed the surfactant to pack more densely at the oil−water interface. Dynamic interfacial tension measurements showed that surfactant adsorption rates increased with salt. As a result of faster adsorption kinetics, oscillating droplet tensiometry showed a decrease in the dilatational modulus when salt was present. An extended DLVO theory was used to calculate the interaction energy between droplets. These calculations agreed well with our experimental results indicating the importance of hydration forces at high salt concentrations and small droplet separation distances. The presence of salt allowed for close surfactant packing and faster surfactant adsorption kinetics, which prevented coalescence and created conditions favorable for the formation of a stable Newton black film.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Impact of Saltwater Environments on the Coalescence of Oil-in-Water Emulsions Stabilized by an Anionic Surfactant

et al. 2021

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“…The surface tension of 43− 53 mN/m obtained in this experiment is close to 52 mN/m as reported about the interfacial tension of the water/decane interface at 25 °C, which also indicates that our results are reasonable. 36 To be specific, after adding degassed water, the increase in surface tension from about 47 to 53 mN/m for droplet 3 implies an evident change of interfacial properties. The increase in surface tensions should be the reason for the increase in contact angles.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Influence of the Dissolved Gas on the Interfacial Properties of Decane Surface Nanodroplets

et al. 2022

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Surface nanodroplets have received extensive attention recently due to their potential in the fabrication of functional materials with nanostructures and chemical reactions at micro-and nanoscales. Although the effect of dissolved gas in water has been realized in some important processes such as spontaneous emulsification of oil droplets in water, its roles in the wetting behavior of surface nanodroplets at the hydrophobic interface have been largely neglected. Here, we focused on the influence of dissolved gas on the interfacial properties of surface nanodroplets and characterized their morphological evolution when exposed to different air-saturated water samples. Results indicated that the morphology of surface nanodroplets barely changed in airoversaturated cold water. However, their contact angle first decreases gradually in deionized water, increases immediately after replacement with degassed water, and eventually decreases gradually with time. Furthermore, the surface tension of nanodroplets would change similarly after the injection of degassed water. We considered these changes to be caused by the removal or reduction of the enriched gas at the substrate interface, in which the surface hydrophobicity was changed. Our findings could shed some light on the wetting behavior of nanodroplets at the hydrophobic surface in different air-saturated water samples and inspire the microscale manipulation and reaction of surface nanodroplets.

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“…The assembled structures can be tuned by varying the directions of the magnetic fields (Movie S1, Supporting Information), which has potential applications in sensor or display technology. To estimate the time scale of the assembly and the structural transition, we assume that colloidal particles of radius a = 4 µm are adsorbed at a decane-water interface, with a surface tension γ = 53.2 mN m −1 , and the effective viscosity μ = 0.91 mPa s. [25,26] Based on our simulation results, the estimated time scale of structural formation and transition is about t ≈ 1 ms, which is sufficiently fast to satisfy the requirements of responsive materials for advanced sensor or display technologies. For a possible experimental realization of our system, we note that magnetic spherical Janus particles have been experimentally fabricated [27][28][29][30] and investigated at a liquid-liquid interface.…”

Section: Doi: 101002/adma202006390mentioning

confidence: 99%

Controllable Capillary Assembly of Magnetic Ellipsoidal Janus Particles into Tunable Rings, Chains and Hexagonal Lattices

Xie

Harting

2021

Advanced Materials

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Colloidal assembly at fluid interfaces has a great potential for the bottom‐up fabrication of novel structured materials. However, challenges remain in realizing controllable and tunable assembly of particles into diverse structures. Herein, the capillary assembly of magnetic ellipsoidal Janus particles at a fluid–fluid interface is reported. Depending on their tilt angle, that is, the angle the particle main axis forms with the fluid interface, these particles deform the interface and generate capillary dipoles or hexapoles. Driven by capillary interactions, multiple particles thus assemble into chain‐, hexagonal‐lattice‐, and ring‐like structures, which can be actively controlled by applying an external magnetic field. A field‐strength phase diagram is predicted in which various structures are present as stable states. Owing to the diversity, controllability, and tunability of assembled structures, magnetic ellipsoidal Janus particles at fluid interfaces could therefore serve as versatile building blocks for novel materials.

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Effect of Water/Decane Ratios and Salt on the Stability, Rheology, and Interfacial Tension of Water/Decane Emulsions

Cited by 20 publications

References 42 publications

Impact of Saltwater Environments on the Coalescence of Oil-in-Water Emulsions Stabilized by an Anionic Surfactant

Impact of Saltwater Environments on the Coalescence of Oil-in-Water Emulsions Stabilized by an Anionic Surfactant

Influence of the Dissolved Gas on the Interfacial Properties of Decane Surface Nanodroplets

Controllable Capillary Assembly of Magnetic Ellipsoidal Janus Particles into Tunable Rings, Chains and Hexagonal Lattices

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