Emulsions and foams

Surfactants ◽  
2019 ◽  
pp. 350-399
Author(s):  
Bob Aveyard
Keyword(s):  
Bubble Size ◽  
Ostwald Ripening ◽  
Volume Fraction ◽  
Laplace Pressure ◽  
Dispersed Phase ◽  
Surfactant Monolayers ◽  
Internal Phase ◽  
Oil In Water ◽  
Small Bubbles ◽  
Oil Type

Methods of formation of emulsions and foams are given; both types of system are stabilized by surfactants. Emulsions can be oil-in-water or water-in-oil type and the preferred type is discussed in terms of the hydrophile–lipophile balance of the system, which ultimately depends on the preferred curvature of close-packed surfactant monolayers at droplet interfaces. Droplet and bubble size distributions in emulsions and foams respectively, evolve with time through Ostwald ripening (bubble disproportionation in foams); larger drops (bubbles) grow at the expense of smaller ones since the Laplace pressure in small bubbles/drops exceeds that in large ones. Creaming occurs in emulsions (if drops are less dense than the medium) and in foams so the volume fraction of dispersed phase, ϕ‎, changes with height. At high ϕ‎ both emulsions and foams assume polyhedral structures giving high internal phase emulsions and ‘dry’ foams, respectively. Methods of breaking unwanted emulsions and foams are described.

The Role of Excess Attractive Particles in the Elasticity of High Internal Phase Pickering Emulsions

Soft Matter ◽  
2021 ◽  
Author(s):  
Junsu Chae ◽  
Siyoung Choi ◽  
KyuHan Kim
Keyword(s):  
Volume Fraction ◽  
Dispersed Phase ◽  
Pickering Emulsions ◽  
High Internal Phase Emulsion ◽  
Internal Phase

A high internal phase emulsion (HIPE), which has a volume fraction of dispersed phase of over 74%, shows a solid like property because of concentrated polyhedral droplets. Although many studies...

Preparation of inverse polymerized high internal phase emulsions using an amphiphilic macro-RAFT agent as sole stabilizer

2016 ◽  
Vol 7 (9) ◽  
pp. 1803-1812 ◽  
Author(s):  
Aminreza Khodabandeh ◽  
R. Dario Arrua ◽  
Christopher T. Desire ◽  
Thomas Rodemann ◽  
Stefan A. F. Bon ◽  
...  
Keyword(s):  
Continuous Phase ◽  
Dispersed Phase ◽  
Internal Phase ◽  
Oil In Water ◽  
Monomer Solution ◽  
Raft Agent

Oil-in-water (‘inverse’) High Internal Phase Emulsions (HIPEs) have been prepared using an amphiphilic macro-RAFT agent with toluene as the internal dispersed phase (∼80 vol%) and an aqueous monomer solution as the continuous phase.

scholarly journals Water-in-Oil Nano-Emulsions Prepared by Spontaneous Emulsification: New Insights on the Formulation Process

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1030
Author(s):  
Salman Akram ◽  
Nicolas Anton ◽  
Ziad Omran ◽  
Thierry Vandamme
Keyword(s):  
Volume Fraction ◽  
Scale Up ◽  
Surface Modifications ◽  
Yield Potential ◽  
Dispersed Phase ◽  
Spontaneous Emulsification ◽  
Oil In Water ◽  
Mixing Rates ◽  
Formulation Parameters ◽  
Nano Emulsion

Nano-emulsions consist of stable suspensions of nano-scaled droplets that have huge loading capacities and are formulated with safe compounds. For these reasons, a large number of studies have described the potential uses of nano-emulsions, focusing on various aspects such as formulation processes, loading capabilities, and surface modifications. These studies typically concern direct nano-emulsions (i.e., oil-in-water), whereas studies on reverse nano-emulsions (i.e., water-in-oil) remain anecdotal. However, reverse nano-emulsion technology is very promising (e.g., as an alternative to liposome technology) for the development of drug delivery systems that encapsulate hydrophilic compounds within double droplets. The spontaneous emulsification process has the added advantages of optimization of the energetic yield, potential for industrial scale-up, improved loading capabilities, and preservation of fragile compounds targeted for encapsulation. In this study, we propose a detailed investigation of the processes and formulation parameters involved in the spontaneous nano-emulsification that produces water-in-oil nano-emulsions. The following details were addressed: (i) the order of mixing of the different compounds (method A and method B), (ii) mixing rates, (iii) amount of surfactants, (iv) type and mixture of surfactants, (v) amount of dispersed phase, and (vi) influence of the nature of the oil. The results emphasized the effects of the formulation parameters (e.g., the volume fraction of the dispersed phase, nature or concentration of surfactant, or nature of the oil) on the nature and properties of the nano-emulsions formed.

scholarly journals Edible CaCO3 nanoparticles stabilized Pickering emulsion as calcium‐fortified formulation

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Xiaoming Guo ◽  
Xiaoying Li ◽  
Leung Chan ◽  
Wei Huang ◽  
Tianfeng Chen
Keyword(s):  
Calcium Carbonate ◽  
Particle Concentration ◽  
Volume Fraction ◽  
Medium Chain Triglyceride ◽  
Pickering Emulsion ◽  
Simulated Intestinal Fluid ◽  
Oral Supplementation ◽  
Internal Phase ◽  
Oil In Water ◽  
Acid Labile

Abstract Background Nanoparticles assembled from food-grade calcium carbonate have attracted attention because of their biocompatibility, digestibility, particle and surface features (such as size, surface area, and partial wettability), and stimuli-responsiveness offered by their acid-labile nature. Results Herein, a type of edible oil-in-water Pickering emulsion was structured by calcium carbonate nanoparticles (CaCO3 NPs; mean particle size: 80 nm) and medium-chain triglyceride (MCT) for delivery of lipophilic drugs and simultaneous oral supplementation of calcium. The microstructure of the as-made CaCO3 NPs stabilized Pickering emulsion can be controlled by varying the particle concentration (c) and oil volume fraction (φ). The emulsification stabilizing capability of the CaCO3 NPs also favored the formation of high internal phase emulsion at a high φ of 0.7–0.8 with excellent emulsion stability at room temperature and at 4 °C, thus protecting the encapsulated lipophilic bioactive, vitamin D3 (VD3), against degradation. Interestingly, the structured CaCO3 NP-based Pickering emulsion displayed acid-trigged demulsification because of the disintegration of the CaCO3 NPs into Ca2+ in a simulated gastric environment, followed by efficient lipolysis of the lipid in simulated intestinal fluid. With the encapsulation and delivery of the emulsion, VD3 exhibited satisfying bioavailability after simulated gastrointestinal digestion. Conclusions Taken together, the rationally designed CaCO3 NP emulsion system holds potential as a calcium-fortified formulation for food, pharmaceutical and biomedical applications.

scholarly journals In-Situ Continuous Monitoring of the Viscosity of Surfactant-Stabilized and Nanoparticles-Stabilized Pickering Emulsions

2019 ◽  
Vol 9 (19) ◽  
pp. 4044 ◽  
Author(s):  
Upinder Bains ◽  
Rajinder Pal
Keyword(s):  
Volume Fraction ◽  
Dispersed Phase ◽  
Pickering Emulsions ◽  
Volume Fractions ◽  
Shear Thinning Fluids ◽  
Oil In Water ◽  
Droplet Sizes ◽  
High Concentrations ◽  
The Stability

An in-situ method of measuring the viscosity of unstable and stable emulsions on a continuous basis under agitation conditions was developed and utilized to investigate the viscous behaviour of surfactant-stabilized and nanoparticles-stabilized oil-in-water (O/W) emulsions at different volume fractions of the dispersed phase (oil). The stability characteristics (droplet size and phase-separation) of emulsions under quiescent conditions were also determined with the aging of emulsions. Emulsions are Newtonian at low volume fractions of the dispersed phase. At high concentrations of the dispersed phase, emulsions behave as non-Newtonian shear-thinning fluids. The nanoparticles-stabilized (Pickering) emulsions are unstable in comparison with the surfactant-stabilized emulsions. The droplet sizes of Pickering emulsions increase rapidly with aging, whereas the droplet sizes of surfactant-stabilized remain nearly the same over a period of 24 h. However, Pickering emulsions are much more viscous than the surfactant-stabilized emulsions when comparison is made at the same volume fraction of the dispersed phase.

Nanoemulsions Loaded with Amphotericin B: Development, Characterization and Leishmanicidal Activity

2019 ◽  
Vol 25 (14) ◽  
pp. 1616-1622 ◽  
Author(s):  
Gabriela Muniz Félix Araújo ◽  
Gabriela Muniz Félix Araújo ◽  
Alana Rafaela Albuquerque Barros ◽  
Alana Rafaela Albuquerque Barros ◽  
João Augusto Oshiro-Junior ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Average Diameter ◽  
Isopropyl Myristate ◽  
Neglected Diseases ◽  
Clinical Form ◽  
Hydrophobic Compounds ◽  
Internal Phase ◽  
Oil In Water ◽  
Spherical Structures ◽  
Lipid Formulations

Leishmaniasis is one of the most neglected diseases in the world. Its most severe clinical form, called visceral, if left untreated, can be fatal. Conventional therapy is based on the use of pentavalent antimonials and includes amphotericin B (AmB) as a second-choice drug. The micellar formulation of AmB, although effective, is associated with acute and chronic toxicity. Commercially-available lipid formulations emerged to overcome such drawbacks, but their high cost limits their widespread use. Drug delivery systems such as nanoemulsions (NE) have proven ability to solubilize hydrophobic compounds, improve absorption and bioavailability, increase efficacy and reduce toxicity of encapsulated drugs. NE become even more attractive because they are inexpensive and easy to prepare. The aim of this work was to incorporate AmB in NE prepared by sonicating a mixture of surfactants, Kolliphor® HS15 (KHS15) and Brij® 52, and an oil, isopropyl myristate. NE exhibited neutral pH, conductivity values consistent with oil in water systems, spherical structures with negative Zeta potential value, monomodal size distribution and average diameter of drug-containing droplets ranging from 33 to 132 nm. AmB did not modify the thermal behavior of the system, likely due to its dispersion in the internal phase. Statistically similar antileishmanial activity of AmB-loaded NE to that of AmB micellar formulation suggests further exploring them in terms of toxicity and effectiveness against amastigotes, with the aim of offering an alternative to treat visceral leishmaniasis.

scholarly journals Long-Term Stability of Different Kinds of Gas Nanobubbles in Deionized and Salt Water

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1808
Author(s):  
Yali Zhou ◽  
Zhenyao Han ◽  
Chunlin He ◽  
Qin Feng ◽  
Kaituo Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Bubble Size ◽  
Ostwald Ripening ◽  
Salt Water ◽  
Dlvo Theory ◽  
Deionized Water ◽  
Hydrodynamic Cavitation ◽  
Term Stability ◽  
Long Term Stability

Nanobubbles have many potential applications depending on their types. The long-term stability of different gas nanobubbles is necessary to be studied considering their applications. In the present study, five kinds of nanobubbles (N2, O2, Ar + 8%H2, air and CO2) in deionized water and a salt aqueous solution were prepared by the hydrodynamic cavitation method. The mean size and zeta potential of the nanobubbles were measured by a light scattering system, while the pH and Eh of the nanobubble suspensions were measured as a function of time. The nanobubble stability was predicted and discussed by the total potential energies between two bubbles by the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The nanobubbles, except CO2, in deionized water showed a long-term stability for 60 days, while they were not stable in the 1 mM (milli mol/L) salt aqueous solution. During the 60 days, the bubble size gradually increased and decreased in deionized water. This size change was discussed by the Ostwald ripening effect coupled with the bubble interaction evaluated by the extended DLVO theory. On the other hand, CO2 nanobubbles in deionized water were not stable and disappeared after 5 days, while the CO2 nanobubbles in 1 mM of NaCl and CaCl2 aqueous solution became stable for 2 weeks. The floating and disappearing phenomena of nanobubbles were estimated and discussed by calculating the relationship between the terminal velocity of the floating bubble and bubble size.

scholarly journals Simulation of the Effect of Oil Volume Fractions in an Oil-Water Flows Along a Circular Pipe: A Finite Element Approach

2018 ◽  
Vol 10 (5) ◽  
pp. 19
Author(s):  
Ferdusee Akter ◽  
Md. Bhuyan ◽  
Ujjwal Deb
Keyword(s):  
Finite Element ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Galerkin Approximation ◽  
Computational Domain ◽  
Two Phase Flows ◽  
Two Phase ◽  
Volume Fractions ◽  
Oil In Water ◽  
Element Approach

Two phase flows in pipelines are very common in industries for the oil transportations. The aim of our work is to observe the effect of oil volume fraction in the oil in water two phase flows. The study has been accomplished using a computational model which is based on a Finite Element Method (FEM) named Galerkin approximation. The velocity profiles and volume fractions are performed by numerical simulations and we have considered the COMSOL Multiphysics Software version 4.2a for our simulation. The computational domain is 8m in length and 0.05m in radius. The results show that the velocity of the mixture decreases as the oil volume fraction increases. It should be noted that if we gradually increase the volume fractions of oil, the fluid velocity also changes and the saturated level of the volume fraction is 22.3%.

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