Emulsions, formation and

Clear Brines. Brine solutions are made from formation saltwater, seawater, or bay water, as well as from prepared saltwater. They do not contain viscosifers or weighting materials. Formation water-base fluids should be treated for emulsion formation and for wettability problems. They should be checked on location to ensure that they do not form a stable emulsion with the reservoir... 

H.-Y. Lee, M. J. McCarthy, S. R. Dungan 1998, (Experimental characterization of emulsion formation and coalescence by nuclear magnetic resonance restricted diffusion techniques), J. Am. Oil Chem. Soc. 75, 463. 

Ester addition must be quite slow (2 drops per second or less) to prevent emulsion formation and extremely low yields. 

This brief review has attempted to discuss some of the important phenomena in which surfactant mixtures can be involved. Mechanistic aspects of surfactant interactions and some mathematical models to describe the processes have been outlined. The application of these principles to practical problems has been considered. For example, enhancement of solubilization or surface tension depression using mixtures has been discussed. However, in many cases, the various processes in which surfactants interact generally cannot be considered by themselves, because they occur simultaneously. The surfactant technologist can use this to advantage to accomplish certain objectives. For example, the enhancement of mixed micelle formation can lead to a reduced tendency for surfactant precipitation, reduced adsorption, and a reduced tendency for coacervate formation. The solution to a particular practical problem involving surfactants is rarely obvious because often the surfactants are involved in multiple steps in a process and optimization of a number of simultaneous properties may be involved. An example of this is detergency, where adsorption, solubilization, foaming, emulsion formation, and other phenomena are all important. In enhanced oil recovery. 

Several detailed discussions have described the complex theories of emulsion technology (1, 2, > 1 ) To summarize these theories, emulsifiers are essential for emulsion formation and stabilization to occur these surface-active compounds reduce the surface and interfacial tensions between two immiscible liquids, but this property accounts for only part of the mechanisms at work in emulsification. Three separate mechanisms that appear to be involved in formation of a stable emulsion include ... 

Viscosity is an important physical property of emulsions in terms of emulsion formation and stability (1, 4). Lissant (1 ) has described several stages of geometrical droplet rearrangement and viscosity changes as emulsions form. As the amount of internal phase introduced into an emulsion system increases, the more closely crowded the droplets become. This crowding of droplets reduces their motion and tendency to settle while imparting a "creamed" appearance to the system. The apparent viscosity continues to increase, and non-Newtonian behavior becomes more marked. Emulsions of high internal-phase ratio are actually in a "super-creamed" state. 

AMPHIPHILIC. Molecule having a water-soluble polar head (hydrophilic) and a water-insoluble organic tail (hydrophobic), e.g.. octyl alcohol, sodium stearate. Such molecules arc necessary for emulsion formation and for controlling the structure of liquid crystals. 

An innovative way to perform a sample cleanup that is fast, accurate, and easy, is the use of solid-phase extraction (SPE) columns. In many ways these devices resemble miniature HPLC columns upon which a preseparation is done. Using these minicolumns for sample clean-up eliminates many of the drawbacks associated with traditional liquid-liquid extraction, such as (1) the use of large amounts of expensive organic solvent, (2) low recovery due to solvent emulsion formation, and (3) large requirements for labor, time, glassware, and bench space. 

The purification of the liquid alkylate from the reaction system is done in a conventional fashion (Figure 5). Before feeding the crude ethylbenzene to distillation, the aluminum chloride and the residual HCl must be completely removed. Water washing accomplishes most of this task final traces are removed by a caustic soda treatment. This process is completely reliable, is free from emulsion formation, and there is no downstream fouling or corrosion to worry about. 

Many surfactants have been suggested as candidates for CO2 foam. However, at high salinity and temperature in the presence of oil, most surfactants foam poorly due to partitioning and emulsion formation and fail to control mobility during CO2 injection. This behavior is analogous to that observed in chemical (microemulsion) oil recovery (5-1). As the salinity, hardness and temperature increase, surfactants form water/oil emulsions, precipitate surfactant-rich coacervate phases, and partition into the oleic phase. CO2 decreases further the solubility of surfactant in the aqueous phase. 

By contrast, dispersion of a phase as small droplets into another under US assistance until the initial heterogeneous liquid-liquid system is made uniform, which is known as homogenization or emulsification , is a well-documented process in both the analytical and industrial fields. Depending on the operating conditions and the type of ultrasound used, both emulsion formation and destruction can be favoured. 

All PTCs have a number of advantages and disadvantages (Table 3.3), and often the system will have to be optimized for a particular reaction to avoid emulsion formation and other problems. However, in most cases, the increase in reaction rate and decrease in the amount of solvent used are significant and often outweigh the disadvantages. Typical reactions that work well under PTC conditions include simple nucleophilic substitutions, Friedel-Crafts reactions, Wittig reactions and oxidations. 

Figure 1. Schematic representation of emulsion formation and breakdown. (Adapted from reference 1.)...

The characterization techniques that will be discussed here are used in field situations, on-line, and in the laboratory. In order to characterize an emulsion, it is necessary to determine the amount of each phase present, the nature of the dispersed and continuous phases, and the size distribution of the dispersed phase. The stability of an emulsion is another important property that can be monitored in a variety of ways, but most often, from a processing point of view, stability is measured in terms of the rate of phase separation over time. This phenomenological approach serves well in process situations in which emulsion formation and breaking problems can be very site specific. However, emulsion stability is ultimately related to the detailed chemistry and physics of the emulsion components and their interactions, and these details cannot be completely ignored. 

Emulsifiers are a single chemical substance, or mixture of substances, that lower the tension at the oil-water interface (interfacial tension) and have the capacity for promoting emulsion formation and short-term stabilisation. 

Lee CT, Psathas PA, Johnston KP. Water-in-carbon dioxide emulsions formation and stability. Langmuir 1999 15 6781-6791. 

Tadros, T.F. (ed.) (1987) Solid/Liquid Dispersions, Academic Press, London. Tadros, T. (ed.) (2013) Emulsion Formation and Stability, Wiley-VCH Verlag GmbH, Weinheim. 

Figure 10.3 Schematic representation of emulsion formation and breakdown.

Using a conventional additive package, fixed-bed gasoline meets other quality standards such as storage stability, copper attack, multimetal corrosion, carburetor detergency, fi1terabi1ity, emulsion formation, and metals retention. 

One of the main problems associated with developing a parenteral or any other solution formulation of a compound is its aqueous solubility. For poorly soluble drug candidates, there are several strategies for enhancing their solubility. These include pH manipulation, cosolvents, surfactants, emulsion formation and complexing agents. More sophisticated delivery systems, e.g., liposomes, can also be used in this way. 

A higher degree of emulsion stability depends on the structure of the compounds that constitute the protective layer formed on the surface of the droplet. The emulsifier adsorbs on the surface of the droplet and covers it with a preserving layer thereby stabilizing the droplet. This layer prevents droplets from merging with each other (i.e. promotes emulsion formation and stability). 

The crucial aspect of emulsion formation and stability is the attainment of the balance between molecular cooperation and competition among emulsifiers at the... 

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