Different Types Of Emulsions Research Articles

Prediction and Experimental Measurements of Water-in-Oil Emulsion Viscosities During Alkaline/Surfactant Injections

Summary Oil production is generally a complicated multiphase flow inside pipelines, with possible water-in-oil (W/O) emulsions present with other usual phases such as free water and free oil. The W/O emulsions formed can present significant hurdles in production facilities for pumping fluids and during pipeline transport. It is well known that high shear rates provided by pumps, chokes, or valves result in stable emulsion behavior for a field in primary production. Several field tests are under way to test the potential of surfactant flooding as a tertiary-recovery mechanism. The effect of addition of surfactants on the emulsion rheology of production fluids, as in alkaline/surfactant/polymer (ASP) flooding, is not very well understood. This understanding of W/O-emulsion rheology in ASP-injection oil recovery is essential for design of pumps and pipelines as well as for handling flow-assurance issues. In this paper, we report results from experiments as well as modeling of W/O-emulsion rheology that can form during ASP injections. We focus here only on the alkaline/surfactant (AS) part of these injections in order to clearly understand the impact of surfactants, removing the uncertainities that come with large rheology changes with polymer addition. The effect of surfactants on the rheology of W/O emulsions was studied by making two different types of emulsions: (1) native-brine W/O emulsions without surfactants to provide a baseline and (2) brine W/O emulsions with surfactants used in ASP injections. This way, the impact of ASP injections on emulsion rheology can easily be quantified. A new correlation is developed, based on in-house historical experimental data, to describe rheology of emulsions without surfactants. This correlation should assist in managing the uncertainties that come from extrapolating emulsion rheology measured in the laboratory to actual field conditions. Further, to understand the effect of ASP injections, new experimental measurements were made by adding surfactants to brine solutions. The addition of surfactants resulted in different rheology as compared with emulsions formed by brine solutions. These differences have been attributed to the W/O interfacial tension (IFT), and IFT was added to modify the original correlation. To our knowledge, this is the first study that explicitly relates emulsion rheology with IFT.

Characterizing Stability of Asphalt Emulsions Using Electrokinetic Techniques

This paper presents the findings from a study conducted to develop a simple quantitative test method to characterize the stability of asphalt emulsions. The proposed method uses electrokinetic techniques to determine the rate at which an asphalt emulsion breaks when subjected to an electric field. The test method was used with different types of emulsion as well as emulsions that were modified by further dilution or mechanical agitation. Results demonstrate that the parameters obtained from these tests were repeatable and different for different types of asphalt emulsions. Results also demonstrate that for a given type of emulsion the test method is sensitive to factors such as water content and partial breaking due to mechanical agitation. The proposed electrokinetics-based method and concomitant parameters provide a repeatable, rapid, and quantitative method by which to characterize asphalt emulsions.

Ceramic foams and micro-beads from emulsions of a preceramic polymer

A commercially available solid silicone resin was dissolved in a solvent and emulsified via stirring in the presence of water and surfactant to form three different types of emulsions, namely water-in-oil (w/o), water-in-oil-in-water (w/o/w) and oil-in-water (o/w), by following different preparation procedures. After curing, thermosets possessing different morphologies, ranging from highly porous (monolithic) foams to porous micro-beads and solid micro-beads, formed. The samples kept their shape upon pyrolysis, and resulted in ceramic foams (via w/o) and porous micron sized (∼200 μm) spherical particles (via w/o/w) having more than 80 vol% of total porosity, while with o/w emulsification solid SiOC ceramic particles with an average diameter of ∼100 μm formed. Both surfactant and water altered the IR spectra for emulsion-derived thermoset samples, in comparison to the pure cured resin, but upon pyrolysis similar amorphous ceramics were obtained from all samples.

Study of Pseudoternary Phase Diagram Behaviour and the Effect of Several Tweens and Spans on Palm Oil Esters Characteristics.

Palm oil esters are high molecular weight esters oil that has been newly synthesized by University Putra Malaysia researchers. It has received a lot of attention for its pharmaceutical and chemical application. The aim of this study is to study the effects of the palm oil esters with different HLB surfactant mixture on the ternary diagrams behaviour and to confine the various systems resulted from these combinations. These systems include traditional emulsion, gel area, transpernat micro-emulsion area, O/W and W/O emulsions. In this study, pseudoternary phase diagrams of water, POEs and non-ionic surfactant mixture of several HLB values were constructed using water titration method. The resultant mixtures collected after each addition and mixing of water were analysed visually, along with conductivity, dilution in water and dye test (methylene blue) to classify them as O/W emulsion (transparent and opaque) or W/O (opaque) and liquid or gel. As a conclusion, palm oil esters were found to be suitable for the formulation of different types of emulsion. Additionally, different HLB value of non-ionic surfactant(s) exhibited different pseudoternary phase diagram characteristics. Keywords: palm oil esters, Tween, Span, Pseudoternary phase diagram, O/W emulsion

W/O/W Emulsions Stabilized by Fat Crystals - Their Formulation, Stability and Ability to Retain Salt

The potential of fat-crystal stabilised W1/O emulsions containing salt to be incorporated into a W1/O/W2 double emulsion was studied. 30% W1/O emulsions stabilised by monoglyceride and triglyceride crystals, and containing 1.6% KCl in the W1 phase, have been mixed with equal amounts of oil and incorporated into double emulsions (W1/O/W2), where the W2 phase contained different levels of different types of emulsifiers (e.g. Na-caseinate). The resulting double structures were monitored over the course of 8 weeks. It was found that double emulsions remain relatively stable during this time depending on the species used to stabilise the external o/w2 interface.

In vitro evaluation of the cutaneous penetration of sprayable sunscreen emulsions with high concentrations of UV filters

The aim of this study was to evaluate the possible penetration through human skin of organic and inorganic filters contained in sunscreen emulsions packaged in aerosol cans, using an in vitro method. Experiments were carried out on two different types of emulsion: W/Si and W/O. This study was conducted using static diffusion cells (Franz cells). The determination of organic UV filters [Methylene Bis Benzotriazolyl Tetramethylbutylphenol (MBBT); Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine (BEMT); Diethylamino Hydroxybenzoyl Hexyl Benzoate (DHHB); Ethylhexyl Methoxycinnamate (EMC); and 2-Ethylhexyl Dimethyl PABA (ED-PABA)] was performed by High Performance Liquid Chromatography (HPLC). Therefore, it was important to develop a single analytical method for the quantification of the five organic filters with the aim of facilitating the experiment. The determination of inorganic filters [titanium dioxide (TiO(2)) and zinc oxide (ZnO)] was performed using an emission spectrometric analysis method (ICP-OES). The HPLC and ICP-OES methods were validated. After a penetration test of 24 h duration, the results showed very low penetration only for two of the organic filters (maximum penetration of 1.21 microg cm(-2) h(-1) for EMC and 0.14 microg cm(-2) h(-1) for MBBT) and no penetration for the inorganic filters. Moreover, more than 50% of each sunscreen agent stayed on the surface on the skin. These results are consistent with those in the literature that presents similar experiments. This study showed that the sprayable sunscreen products developed, which contained high concentrations of UV filters, presented a low level of skin penetration.

Development of Lapachol Topical Formulation: Anti-inflammatory Study of a Selected Formulation

This study aimed at developing a topical formulation of lapachol, a compound isolated from various Bignoniaceae species and at evaluating its topical anti-inflammatory activity. The influence of the pharmaceutical form and different types of emulsifiers was evaluated by in-vitro release studies. The formulations showing the highest release rate were selected and assessed trough skin permeation and retention experiments. It was observed that the gel formulation provided significantly higher permeation and retained amount (3.9-fold) of lapachol as compared to the gel-cream formulation. Antinociceptive and antiedematogenic activities of the most promising formulation were also evaluated. Lapachol gel reduced the increase in hind-paw volume induced by carrageenan injection and reduced nociception produced by acetic acid (0.8% in water, i.p.) when used topically. These results suggest that topical delivery of lapachol from gel formulations may be an effective medication for both dermal and subdermal injuries.

Comparison of solid particles, globular proteins and surfactants as emulsifiers

The aim of this paper is to present a short overview of the main mechanisms operative in the formation and stabilization of emulsions by solid particles and, on this basis, to make comparisons between solid particles, surfactants and globular proteins as emulsifiers. When available, simple quantitative relations are presented, with the respective numerical estimates and discussion of the applicability of these relations to particle-stabilized systems. Non-obvious similarities between the different types of emulsifiers are outlined in several cases in which the description of the system can be performed at a phenomenological level. Examples are presented for the process of emulsification, where we show that several simple theoretical expressions, derived originally in the studies of surfactants and protein emulsifiers, can be successfully applied to particle-stabilized emulsions. In contrast, for the phenomena in which the detailed mechanisms of particle adsorption and film stabilization are important, the differences between the various emulsifiers prevail, thus making it impossible to use the same theoretical description. The most important specific characteristics of the solid particles which strongly affect their behavior are the high barrier to particle adsorption, high desorption energy and strong capillary forces between particles trapped in liquid films, which all originate in the relatively large particle size (as compared to the size of surfactant and protein molecules). The capillary mechanism of stabilization of liquid films by solid particles is reviewed in some detail, to emphasize its specific features and to demonstrate the applicability of several simple expressions for approximate estimates. Interestingly, we found that the hypothesis for some exceptionally high coalescence stability of the particle-stabilized emulsions is not supported by the experimental data available in literature. On the other hand, the particles are able to completely arrest the process of Ostwald ripening in foams and emulsions, and this effect can be easily explained with the high desorption energy of the particles and the resulting capillary effects.

Modeling emulsification after an oil spill in the sea

A conceptual model for simulating oil emulsification after a spill in the ocean is presented. This paper contains the complete model formulation and scenario simulations. The model formulation is based on the most up-to-date research information available in the literature. The model uses minimum turbulence energy as a criterion to determine whether emulsification occurs. Once the emulsification happens, the model simulates water uptake and viscosity changes during emulsification. The model classifies emulsion into three categories: stable, meso-stable, and unstable emulsions based on a concept “stability index”. The model estimates the stability of the emulsion and simulates the process of de-emulsification when the emulsion is meso-stable or unstable. The model also considers the effects of evaporation on the formation of emulsification. Scenario simulations show how different types of emulsions are formed under different conditions. They also show how the emulsion stability changes with oil weathering.

Semi‐continuous emulsion copolymerization of vinyl acetate and butyl acrylate using a new protective colloid. Part 1. Effect of different emulsifiers

AbstractVinyl acetate and butyl acrylate copolymers were synthesized in the presence of ammonium persulfate initiator, emulsifiers having different character such as non‐ionic and anionic+non‐ionic emulsifiers, and N‐methylol acrylamide as a new protective colloid in a classical glass reactor. The monomer ratio was chosen 85:15. In the case of mixture emulsifiers, the series of non‐ionic emulsifiers which have 10 to 40 moles ethoxylated nonyl phenol except 20 moles were combined with sodium dodecyl benzene sulfonate. The effects of the new colloidal stabilization agent, and different emulsifiers on the physicochemical properties of the copolymers were investigated at a constant temperature of 70°C by measuring conversion, viscosity, molecular weights, and molecular weight distribution, respectively, by using gravimetric method, Brookfield viscometer, viscometric method, and gel permeation chromatograpy. It was determined that the original copolymer latexes viscosities increased with the increased chain length for the two types of emulsifiers, in general. Similar changes were also found in viscosity average, number average and weight average molecular weights of the copolymers for the different types of emulsifiers. Copyright © 2006 John Wiley & Sons, Ltd.

Effects of different emulsifier types, fat contents, and gum types on retardation of staling of microwave-baked cakes.

The effects of different types of emulsifiers, gums, and fat contents on the retardation of staling of microwave-baked cakes were investigated. First, different types of emulsifiers (DATEM, Lecigran, and Purawave) at three different fat contents (50%, 25%, and 0%) were added to cake formulations to retard staling of microwave-baked cakes. Then, three types of gums (guar gum, xanthan gum, and methylcellulose) were added to the optimum formulations chosen. As a control, cakes formulated without any emulsifier or gum addition and baked in an conventional oven at 175 degrees C for 25 min was used. Weight loss, firmness, soluble starch and amylose content of the cakes were used as the indicators of staling criteria. Cakes were baked in a microwave oven for 1.5 min at 100% power. Variation of staling parameters during storage of cakes followed zero-order kinetics. Use of emulsifiers and gums helped to retard staling of microwave-baked cakes. Fat content was found to be a significant factor in affecting variation of firmness and weight loss of the cakes during storage. DATEM and Purawave were the most effective emulsifier types. Using gums in combination with emulsifiers gave better moisture retention and softer cakes than using gums alone.

A didodecyldimethylammonium bromide ternary system: Characterization of three‐phase stable emulsions by optical microscopy

AbstractA preliminary characterization of the didodecyldimethyl ammonium bromide (DDAB)/water (W)/per fluorooctane (PFO) ternary system at 25°C is presented. The gradual addition of water, followed by mixing, to DDAB/PFO mixtures produces very stable emulsions for water contents greater than 20 wt%. On the basis of macroscopic observation, at least four different types of emulsions form up to a water content of around 97 wt%. On the basis of high conductivity values, a water‐continuous domain is suggested at all compositions. A second phase diagram, considerably different in phase boundaries, is obtained by adding the PFO oil to DDAB/W samples. This allowed us to ascertain the swelling properties of Lα1 and Lα2 lamellar phases. Optical microscopy in the presence and in the absence of polarized light revealed the formation of lamellar liquid crystals either as randomly localized islands or as rings surrounding the oil droplets. Vesicles are identified at high water content. The contemporaneous presence of both Lα1 and Lα2 lamellar phases causes a synergistic effect in the PFO stabilization.

Fluorocarbons and fluorinated amphiphiles in drug delivery and biomedical research

The specific properties of fluorocarbons, exceptional chemical and biological inertness, high gas-dissolving capacity, low surface tension, excellent spreading characteristics and high fluidity, have triggered numerous applications of these compounds in oxygen delivery. An injectable emulsion of fluorocarbon-in-water destined to deliver oxygen to tissues at risk of hypoxia has now completed Phase III clinical trials in Europe. A neat fluorocarbon is currently investigated in Phase II for treatment of acute respiratory failure by liquid ventilation. Fluorinated lipids and fluorinated surfactants can be used to elaborate and stabilize various colloidal systems, including different types of emulsions, vesicles and tubules, that also show promise for controlled release drug delivery.

Control of zirconia particle size by using two-emulsion precipitation technique

Zirconia powder is synthesized in two types of reverse emulsions, i.e., macroemulsion and microemulsion. In either of the systems, two solutions of reverse emulsion, one containing Zr 4+ aqueous droplets and the other aqueous ammonia droplets, with the same water/oil (w/o) ratio are prepared separately and mixed together to form a slurry of ZrO 2 precursors. Then the precursors are recovered and calcined to form tetragonal ZrO 2. Factors that affect the emulsion stability and particle size are investigated, including type of oil, w/o ratio, type and concentration of surfactant, concentration of aqueous solutions, and mixing intensity. The difference in particle size and thus calcination temperature is significant between the zirconia crystals produced from the two different types of emulsions. Thus, coupling the macroemulsion and microemulsion precipitation processes, the mean size of spherical ZrO 2 particles ranging from tens of nanometers to a few micrometers can be controlled.

Two-dimensional gels

Abstract Cross-linked membranes are interesting model systems for numerous applications in industry and science. Such structures can be formed from different types of diesters just at the interface between oil and water. We have systematically studied rubber-elastic, glass-like and transient membranes which are stablized by physical or chemical contacts. The cross-linking process occurs through radical reactions which can be initiated by UV irradiation. This interfacial polymerization is not restricted to flat surfaces, and the corresponding films can be used for the stabilization of different types of emulsions. Oil droplets which are surrounded by cross-linked membranes, form simple systems which exhibit interesting rheological properties. During flow, deformation and breaking processes occur which are strongly influenced by the elastic properties of the enclosing membrane.

From two‐dimensional model networks to microcapsules

AbstractThe tensio‐active properties of different types of diesters can be used to synthesize two‐dimensional model networks at the interface between oil and water. We have systematically studied rubber‐elastic, glass‐like and transient membrances which are stabilized and crosslinked by physical or chemical contacts.The adsorption process of the monomeric diesters was investigated by measuring the interfacial tension at the boundary between oil and water. The experimental results can be interpreted on the basis of the “Szyskowski”‐ equation which holds for monomolecular films under ideal conditions. From the measured values of the interfacial tension it is possible to determine the surface concentration. The polymerization process occurs through radical‐reactions which can be initiated by UV‐irradiation.We have systematically studied the kinetics of surface gelation by measuring the two‐dimensional shear modulus as a function of the reaction time. The experimental results can be interpreted in the framework of simple reaction mechanisms. The quantitative analysis of the experimental data allows to evaluate many details of the photo‐reaction as the free radical concentration. the number of linear chains and the rate constant of the cross‐linking process.The two‐dimensional sol‐gel transition can easily be described in the framework of percolation theories which were proposed by Stauffer and de Gennes. According to these models, one expects to find a steep increase in the elastic modulus after passing the gel point. The two‐dimensional percolation exponent, determined in our experiments, agrees very well with the calculated result of 4/3. This holds for rubber‐elastic and glass‐like membranes.Rubber‐elastic, cross‐linked films exhibit interesting features, which can be explained by simple models. The shear modulus depends upon the surface concentration of elastically effective chains. The interfacial polymerization is not restricted to flat surfaces, and the corresponding films can be used for the stabilization of different types of emulsions. Oil droplets which are surrounded by cross‐linked membranes, from simple systems which exhibit interesting properties of biological cells. The microcapsules can, for instance, be used in order to simulate blood flow in living vessels. We have measured the deformation process and the aggregation behavior of these microcapsules in Couette flow under a microscope, and we have investigated the influence of the membrane elasticity on the flow behavior of these emulsions. The data, thus obtained, can be compared with the particle behavior of rigid spheres and deformable liquid drops. The rheological properties of these artificial cells are useful to get a clearer picture of the complicated flow processes which occur in biological systems.

Reciprocity Law for X-Rays* Part II: Failure in the Reversal Region

Experimental data are presented that show the reversal behavior of the characteristic curves for one commercial x-ray film as a function of x-ray exposure rate and establish the presence of reciprocity-law failure and intermittency effect in the reversal region. Under the present experimental conditions, lower exposure rates of x-radiation are seen to favor reversal while the opposite is shown to be the case for visible light. Earlier work with different types of emulsions and under different developing conditions mentions an effect with visible light similar to the one here obtained with x-rays; however, a satisfactory interpretation of the basic mechanisms involved is still lacking and further experiments are required to establish the connection between the effects of x-rays and visible light.

Graphical Analysis of Photographic Exposure and a New Theoretical Formulation of the H and D Curve*

A graphical analysis of the photographic exposure problem is given based on the assumption that the sensitivity variation among grains of a photographic emulsion depends upon an inherent variation in grain sensitivity among grains of the same size class as well as upon the size distribution. Using the graphical model developed, a theoretical equation of the H and D curve is derived. On account of the mathematical form, the equation cannot be integrated. It is necessary, therefore, to obtain the theoretical curves from this equation by graphical methods. Curves obtained by means of the equation are compared with experimental curves for three widely different types of emulsions, and the agreement is quite satisfactory.