Give four uses of emulsions?

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Emulsions are basically the mixture of two or more liquids in which one is present as droplets, of microscopic or ultramicroscopic size, distributed throughout the other.Here are the uses →

• Milk which is an important constituent of our diet is en emulsion of liquid fats in water.
• The cleansing action of ordinary soap for washing clothes, crockery etc. is based upon the formation of oil-in-water emulsion.
• Several oily drugs and medicines are prepared in the form of emulsions since they are easily absorbed by the body.
• Asphalt emulsified in water is used for building roads without the necessity of melting the asphalt.

In food

Oil-in-water emulsions are common in food:

Crema (foam) in espresso – coffee oil in water (brewed coffee), unstable emulsion

Mayonnaise and Hollandaise sauce – these are oil-in-water emulsions that are stabilized with egg yolk lecithin, or with other types of food additives, such as sodium stearoyl lactylate

Homogenized milk – an emulsion of milk fat in water and milk proteins

Vinaigrette – an emulsion of vegetable oil in vinegar. If this is prepared using only oil and vinegar (i.e., without an emulsifier), an unstable emulsion results

Water-in-oil emulsions are less common in food but still exist:

Butter – an emulsion of water in butterfat

In medicine
20 ml ampule of 1% Propofol emulsion suitable for intravenous injection. The manufacturers emulsify lipid-soluble Propofol in a mixture of water, soy oil, and egg lecithin.In pharmaceutics, hairstyling, personal hygiene, and cosmetics, emulsions are frequently used. These are usually oil and water emulsions but dispersed, and which is continuous depends in many cases on the pharmaceutical formulation. These emulsions may be called creams, ointments, liniments (balms), pastes, films, or liquids, depending mostly on their oil-to-water ratios, other additives, and their intended route of administration. The first 5 are topical dosage forms, and may be used on the surface of the skin, transdermally, ophthalmically, rectally, or vaginally. A highly liquid emulsion may also be used orally, or may be injected in some cases. Popular medications occurring in emulsion form include calamine lotion, cod liver oil, Polysporin, cortisol cream, Canesten, and Fleet.

Microemulsions are used to deliver vaccines and kill microbes. Typical emulsions used in these techniques are nanoemulsions of soybean oil, with particles that are 400-600nm in diameter. The process is not chemical, as with other types of antimicrobial treatments, but mechanical. The smaller the droplet the greater the surface tension and thus the greater the force required to merge with other lipids. The oil is emulsified with detergents using a high-shear mixer to stabilize the emulsion so, when they encounter the lipids in the cell membrane or envelope of bacteria or viruses, they force the lipids to merge with themselves. On a mass scale, in effect this disintegrates the membrane and kills the pathogen. The soybean oil emulsion does not harm normal human cells, or the cells of most other higher organisms, with the exceptions of sperm cells and blood cells, which are vulnerable to nanoemulsions due to the peculiarities of their membrane structures. For this reason, these nanoemulsions are not currently used intravenously (IV). The most effective application of this type of nanoemulsion is for the disinfection of surfaces. Some types of nanoemulsions have been shown to effectively destroy HIV-1 and tuberculosis pathogens on non-porous surfaces.

In firefighting

Emulsifying agents are effective at extinguishing fires on small, thin-layer spills of flammable liquids (Class B fires). Such agents encapsulate the fuel in a fuel-water emulsion, thereby trapping the flammable vapors in the water phase. This emulsion is achieved by applying an aqueous surfactant solution to the fuel through a high-pressure nozzle. Emulsifiers are not effective at extinguishing large fires involving bulk/deep liquid fuels, because the amount of emulsifier agent needed for extinguishment is a function of the volume of the fuel, whereas other agents such as aqueous film-forming foam (AFFF) need cover only the surface of the fuel to achieve vapor mitigation.