Where is emulsion found

The HLD system works for ionic as well as non-ionic surfactants, and it is better able to take into account detailed characteristics of a particular emulsion such as salinity, oil type, surfactant concentration, and temperature. For example, a very hydrophilic emulsifier, sodium laurel sulfate, has a Cc of —2. The Cc for combinations of emulsifiers is the weighted average for each emulsifier.

The HLD scale centers on 0, which corresponds to the optimal emulsion. Online calculators exist to optimize the HLD for a particular emulsion e. Increasingly, formulators are interested in making microemulsions, which offer greater stability than conventional macroemulsions.

As the name suggests, microemulsions have smaller droplet sizes than regular emulsions, making them appear transparent rather than opaque. Unlike macroemulsions, microemulsions are thermodynamically stable.

In contrast, a macroemulsion requires an energy input to reappear. Microemulsions are made differently from macroemulsions. Macroemulsions require high-intensity mixing. Because microemulsions are a thermodynamically stable end point that a system naturally migrates toward, they generally do not require vigorous mixing. However, formulators often use gentle agitation to evenly spread the components and speed up the process of microemulsion formation.

Compared to macroemulsions, microemulsions require more surfactant. Because of their remarkable stability, microemulsions are finding applications in diverse fields such as personal care products, oil field chemicals, and medicine. Many popular food items are emulsions, including mayonnaise, salad dressings, sauces such as Hollandaise, chocolate, and ice cream. Worldwide, most commercial lecithin comes from soybean oil.

Egg yolk, the traditional emulsifier for mayonnaise and sauces, also contains lecithin. Other common emulsifiers in foods are proteins, fatty acid esters, sodium stearoyl lactylate, and mono- and diglycerides. These differences may arise from seemingly subtle variations in plant conditions.

This emulsifier can substitute for soy lecithin, which has recently come under fire, particularly in Europe, because most soy crops grown for export especially the United States, Brazil, and Argentina are genetically modified.

Non-genetically modified soy is expensive and in short supply. Therefore, CITREM may prove an attractive alternative for confectioners who want to avoid ingredients made from genetically modified soy. Sustainable sourcing of palm oil has also become a customer concern, as reports have surfaced that the development of palm oil plantations harms the environment and threatens endangered wildlife in Malaysia and Indonesia, where most palm oil originates. As a result, DuPont introduced a portfolio of emulsifiers based on sustainably sourced palm and non-palm oils.

Reduced-fat emulsions are another hot topic for the food industry. When fat is removed from a food to make a reduced-fat or fat-free version, the taste, appearance, and texture often suffer. Julian McClements, professor of physico-chemistry at the University of Massachusetts Amherst, USA, says that there are several ways that emulsions or emulsifiers could help reduce the fat content of foods. Another approach, called heteroaggregation, is to mix oil droplets coated with emulsifiers of opposite charge.

Researchers are exploring emulsions as delivery vehicles for vitamins, supplements, and other nutraceuticals. Eventually, he would like to incorporate nutraceuticals such as these into functional foods. Different types of emulsions could have different applications. Multilayer emulsions consist of oil droplets coated with an emulsifier plus one or more biopolymer layers, dispersed in an aqueous solution.

The emulsifier is typically electrically charged, and the polymer layer s have opposite charges that attract them to the surface of the oil droplet.

According to McClements, multilayer emulsions tend to have better physical stability than single-layer emulsions through fluctuations in pH, ionic strength, temperature, freezing and thawing, and dehydration.

In addition, researchers can design multilayer emulsions to control their breakdown in the gastrointestinal tract. Most personal care products, including lotions, creams, shampoos, and conditioners, are emulsions. Common emulsifiers for personal care products include ethoxylated alcohols, carboxylates, sodium isethionate, glycerol monostearate, cetyl alcohol, stearyl alcohol, and silicone emulsifiers such as dimethicones.

Synthetic emulsifiers such as ethoxylated alcohols and their naturally derived counterparts have identical structures, performance, and biodegradation. When an emulsion has small diameter droplets large surface area , it has a light color. When an emulsion has large diameter droplets low total interfacial surface area , it generally looks dark and less bright. Understanding the characteristics of an emulsion by visual observation is an art that improves with experience.

It is also referred to as BSW, bottom settlings and water, or bottom solids and water. Several methods are available to determine the amount of water and solids in emulsions. Standard methods have been proposed by several organizations including the [5] :. The amount of solids and water separated is measured directly from specially designed centrifuge tubes. When only the water content is desired, Karl-Fischer titration can also be used. Other, less common methods are based on [5] :.

Produced oilfield emulsions generally have droplet diameters that exceed 0. Emulsions normally have a droplet size range that can be represented by a distribution function. The droplet-size distribution in an emulsion depends on several factors including the:.

Droplet-size distribution in an emulsion determines, to a certain extent, the stability of the emulsion and should be taken into consideration in the selection of optimum treatment protocols. As a rule of thumb, the smaller the average size of the dispersed water droplets, the tighter the emulsion and, therefore, the longer the residence time required in a separator, which implies larger separating plant equipment sizes.

The photomicrographs in Figs. The droplet-size distribution for oilfield emulsions is determined by the following methods. Emulsion viscosity can be substantially greater than the viscosity of either the oil or the water because emulsions show non-Newtonian behavior. This behavior is a result of droplet crowding or structural viscosity. A fluid is considered non-Newtonian when its viscosity is a function of shear rate.

At a certain volume fraction of the water phase water cut , oilfield emulsions behave as shear-thinning or pseudoplastic fluids i. The non-Newtonian behavior is pseudoplastic or shear-thinning behavior. Temperature also has a significant effect on emulsion viscosity. Emulsion viscosity decreases with increasing temperature the data have been plotted on a semilog scale. The viscosity of emulsions depend on several factors:.

The ratio of the viscosity of an emulsion to the viscosity of the virgin crude oil at the same temperature can be approximated by the following equation. Emulsion viscosity depends on several factors, and Eq.

For more precise values, experimental data must be used. Emulsion viscosity is measured by standard viscometers, such as capillary tube and rotational viscometers:. It is important that temperature is constant and quoted with the viscosity data. Special procedures must be adopted for measuring the rheology of emulsions.

The previous discussion on viscosity was limited to bulk emulsion viscosity. As mentioned previously, water-in-oil emulsions form rigid interfacial films encapsulating the water droplets. These interfacial films stabilize an emulsion by lowering IFT and increasing interfacial viscosity. These films retard the rate of oil-film drainage see Stability of oil emulsions during the coalescence of water droplets, thereby greatly reducing the rate of emulsion breakdown.

The oil-drainage rate depends on the interfacial shear viscosity. High interfacial viscosities significantly slow the liquid drainage rate and thus have a stabilizing effect on the emulsion. Emulsion interfacial viscosity plays a very important role in demulsification. Several sources [9] [10] [11] provide a detailed discussion of measurement techniques and application to emulsion stability.

Agrell, J. Society of Petroleum Engineers. Alboudwarej, H. Rheology of Heavy-Oil Emulsions. Al-Ghamdi, A. Beetge, J. Dalmazzone, C. Fjeldly, T. Janssen, P. Emulsion Formation in a Model Choke-valve. Kalra, A. Kokal, S. Munoz, V. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Anne Marie Helmenstine, Ph.

Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels.

Facebook Facebook Twitter Twitter. Updated January 31, Key Takeaways: Emulsions An emulsion is a type of colloid formed by combining two liquids that normally don't mix. In an emulsion, one liquid contains a dispersion of the other liquid. Common examples of emulsions include egg yolk, butter, and mayonnaise. The process of mixing liquids to form an emulsion is called emulsification. Even though the liquids that form them may be clear, emulsions appear cloudy or colored because light is scattered by the suspended particles in the mixture.

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