Effect of Nanoparticle Hydrophobicity on Stability of Highly Concentrated Emulsions

Tshilumbu, Nsenda Ngenda; Kharatyan, Ellina; Masalova, Irina

doi:10.1080/01932691.2013.775584

Cited by 19 publications

(9 citation statements)

References 46 publications

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“…Recently, CNTs and several other nanoparticles were incorporated into HCEs either as Pickering stabilizers or as co-stabilizers, and the role of various factors such as the particle size, hydrophobicity, and surfactant/particle ratio on the emulsion stability was studied. − Multiwalled CNTs (MWCNTs) were also utilized as “cosurfactants” along with conventional surfactants to prepare w/o HCEs . Studies on poly high internal phase emulsion (polyHIPE) composite foams provided some useful insights regarding the formation of percolating networks in HCEs. − Conductive polyHIPE composites having a low electrical percolation threshold were prepared by the polymerization of highly concentrated w/o emulsions incorporated with CNTs, where CNTs were either added in the aqueous phase or in the organic phase.…”

Section: Introductionmentioning

confidence: 99%

Effect of Incorporation of Multiwalled Carbon Nanotubes on the Microstructure and Flow Behavior of Highly Concentrated Emulsions

et al. 2018

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Multiwalled carbon nanotubes (MWCNTs) were incorporated into highly concentrated water-in-oil emulsions with the ultimate aim of achieving a uniform and effective dispersion of MWCNTs within the emulsion matrix. The emulsion was formulated in such a way, wherein the internal phase consists of higher than 90 wt %. By keeping the same aqueous-to-oil phase ratio, the amount of MWCNTs in the oil phase was systematically adjusted to investigate their effects on the microstructure development and rheological behavior of the emulsion. The addition of MWCNTs led to a reduced droplet size and also resulted in a narrower distribution of the droplet size. The rheological behavior of nanotube-incorporated emulsions was characterized with varying MWCNT concentrations and also as a function of the emulsification time. The rheological characteristics of the nanotube-incorporated emulsions were identical to those of the neat emulsion and were primarily governed by the variation in the droplet size and droplet-size distribution. However, the yield strain and cross-over strain were independent of the mean droplet size and polydispersity of the emulsion. Emulsions that have smaller droplets exhibited higher storage modulus ( G ′), yield stress (τ Y ), and apparent viscosity (η). For all refining times investigated, nanotube-incorporated emulsions have higher G ′, τ Y , and η values when compared to the neat emulsion, and these values further increased with the MWCNT concentration. This was primarily due to the decrease in the droplet size with MWCNT addition. Furthermore, our findings suggest that the incorporated MWCNTs did not induce any significant change in the rheological behavior of emulsions with identical droplet sizes, and it remained essentially unchanged with the concentration of MWCNTs. However, the nanotube-incorporated emulsions possessed solidlike behavior up to a higher applied stress when compared to a neat emulsion of identical droplet size.

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Section: Introductionmentioning

confidence: 99%

Effect of Incorporation of Multiwalled Carbon Nanotubes on the Microstructure and Flow Behavior of Highly Concentrated Emulsions

et al. 2018

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“…Emulsions are one of the important classes of multiphase materials. − Usually, they are considered thermodynamically unstable because of their high inner interfacial area and can be stabilized only kinetically, for example, using particles. − However, this general view is challenged by numerous observations on spontaneous emulsification. − These observations hold a promise for thermodynamically stable emulsions.…”

Section: Introductionmentioning

confidence: 99%

On the Negative Surface Tension of Solutions and on Spontaneous Emulsification

Kaptay

2017

Langmuir

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The condition of negative surface tension of a binary regular solution is discussed in this paper using the recently reconfirmed Butler equation (Langmuir 2015, 31, 5796-5804). It is shown that the surface tension becomes negative only for solutions with strong repulsion between the components. This repulsion for negative surface tension should be so strong that this phenomenon appears only within a miscibility gap, that is, in a two-phase region of macroscopic liquid solutions. Thus, for a macroscopic solution, the negative surface tension is possible only in a nonequilibrium state. However, for a nano-solution, negative surface tension is also possible in equilibrium state. It is also shown that nano- and microemulsions can be thermodynamically stable against both coalescence and phase separation. Further, the thermodynamic theory of emulsion stability is developed for a three-component (A-B-C) system with A-rich droplets dispersed in a C-rich matrix, separated by the segregated B-rich layer (the solubility of B is limited in both A and C while the mutual solubility of A and C is neglected). It is shown that when a critical droplet size is achieved by forced emulsification, it is replaced by spontaneous emulsification and the droplet size is reduced further to its equilibrium value. The existence of maximum temperature of emulsion stability is shown. Using low-energy emulsification below this maximum temperature, spontaneous emulsification can appear, which is enhanced with further decrease of temperature. This finding can be applied to interpret the experimental observations on spontaneous emulsification or for the design of stable micro- and nanoemulsions.

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“…Surfactant remediation was earlier the chief technique to take care of oil spills in land. Other methods such as utilization of biological microbes to degrade diesel have also been reported in literature …”

Section: Introductionmentioning

confidence: 99%

Characterization and Application of Surfactant Foams Produced from Ethanol‐Sodium Lauryl Sulfate‐Silica Nanoparticle Mixture for Soil Remediation

Karthick¹

2017

Macromolecular Symposia

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Soils contaminated with diesel oil spilling from industrial areas, pipelines constitute a major environmental problem. This subsequently leads to the contamination of groundwater as well. Hence recently there is an increasing trend of usage of better techniques and agents that can perform diesel oil contaminated soil remediation with greater efficiency. The aim of this study is to report the potential, efficiency of using silica nanoparticle stabilized anionic surfactant foams for diesel contaminated soil remediation and also the different characteristics of the foam produced. Also comparison in terms of soil remediation efficiency using surfactant dispersions only were performed. The foams were produced from dispersions comprising of ethanol, anionic surfactant sodium lauryl sulfate (SLS) and silica nanoparticles, both hydrophobic and hydrophilic. The foamability and stability of the different foams were determined using the Dynamic Foam Analyzer DFA 100 (Kruss GmbH, Germany). The surfactant foams generated were then applied to the contaminated soil using a fabricated column. The results showed the gradual stabilization of the SLS foams by the use of the silica nanoparticles. The maximum diesel oil removal efficiency obtained by applying foam stabilized with 0.3 wt% hydrophobic silica nanoparticle, 10 vol% ethanol, 0.1 vol% SLS was 94.5%. The 0.3 wt% hydrophobic silica nanoparticle, 10 vol% ethanol, 0.1 vol% SLS surfactant solution showed only 61.5% maximum oil removal efficiency.

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Effect of Nanoparticle Hydrophobicity on Stability of Highly Concentrated Emulsions

Cited by 19 publications

References 46 publications

Effect of Incorporation of Multiwalled Carbon Nanotubes on the Microstructure and Flow Behavior of Highly Concentrated Emulsions

Effect of Incorporation of Multiwalled Carbon Nanotubes on the Microstructure and Flow Behavior of Highly Concentrated Emulsions

On the Negative Surface Tension of Solutions and on Spontaneous Emulsification

Characterization and Application of Surfactant Foams Produced from Ethanol‐Sodium Lauryl Sulfate‐Silica Nanoparticle Mixture for Soil Remediation

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