Emulsion is a liquid mixture

Emulsion is a mixture of substances. In it, one component consists of the smallest particles, insoluble in the other. This ingredient is called a "dispersed phase". Another substance is a dispersed medium. In it the first component is distributed. "Emulsion" is a term that has a Latin origin. In translation, it means "I'm giving away, milking." Let us consider this concept in more detail.

General information

Of any two liquids that do not mix and do not react chemically, you can make an emulsion. Water is almost always a component. Another substance consists of weakly polar or neutral molecules (eg fats). The first known emulsion is milk. Here, the fat particles are dispersed in water. The size of the smallest particles of the dispersed phase is 1-50 μm, so emulsions refer to coarsely dispersed systems. Low-concentrated liquids are unstructured. Mixtures with a high concentration are structured. According to thermodynamic features, an oil emulsion is an unstable system. The dimensions of the phase drops are large, and the mixture will be unstructured.

Classification

The type of emulsion obtained depends on the ratio of the volume of phases and their composition, on the amount and nature of the emulsifier, its chemical activity, on the method and method of mixing.

1. Direct mixtures with the smallest particles of non-polar and insoluble liquid in the polar phase (m / in - from the expression "oil in water"). For such mixtures, it is possible to use emulsifiers that dissolve in water, for example bitumen particles. Their molecules are adsorbed on surface films of the m-phase, reducing not only the tension, but also creating a strong film.
2. Inverse (w / w) mixture, for which water-insoluble emulsifiers are used.

Chemical effects on the emulsion, pressure, composition change can lead to inverting.

1. Lyophilic emulsion is a mixture formed spontaneously, spontaneously. It is thermodynamically considered stable. An example is the critically stable emulsion when the limiting temperature for phase mixing is reached. The same category includes lubricating oils and liquids for cooling.
2. Lyophobic emulsion is a mixture formed by mechanical, acoustic or electrical mixing. Thermodynamically, they are extremely unstable. Such mixtures without emulsifiers for a long time do not exist. Good components for them: surfactants, high-molecular, water-soluble substances, solids with high dispersity.

Receiving

There are two technologies for the production of emulsion. The first is the path of fine fragmentation of fractions. The second is the process of film formation with subsequent rupture into small parts. In the first variant, the substance is slowly added to the dispersed system. At the same time, it is necessary, while carrying out the connection, to mix constantly at high speed. In this case, the quality of the mixture will depend on various factors. In particular, on the speed of mixing, the introduction and volume of the substance being dispersed, its concentration, temperature and acidity of the medium. The second method is the process by which a film is formed on the surface of another phase. From the bottom, air is pumped. Bubbles burst the film into small drops and mix the entire volume of liquid. In our time, instead of air, ultrasound was used . This causes the film to be crushed into even smaller parts.

Destruction of mixtures

With the passage of time, spontaneous decomposition of the emulsion occurs. There are times when it is necessary to accelerate this process and reduce the concentration of the compound. This need is relevant when the presence of a highly concentrated emulsion interferes with the processing of the material or its correct application. Speed up the process of reducing the concentration of the solution in several ways:

1. Chemical method. Reagents are used that destroy the surface films of the emulsifier itself. In this case, the negative charge concentrating on the surface film is neutralized. The same principle is based on the use of organic supplements of dietary supplements (biologically active substances - demulsifiers).
2. Addition of an emulsifier that causes the formation of cations, which attract a negative surface charge and cause destabilization of the surface films of the emulsifier. Stability of the solution state decreases.
3. Substitution of the emulsifier with another surfactant (surfactant). It dilutes the concentration of the first, but does not form a sufficiently strong film.
4. Thermal method. In this method, the emulsion is subjected to a temperature effect, which causes its stratification.
5. Mechanical method. This option is also called the separator method. The emulsion is slowly pumped into a container rotating at a high angular velocity . The solution decomposes into constituents by weight of the fractions.
6. Method of electric shock or addition of electrolyte to the emulsion. In this way, the surface films of the mixtures stabilized by the negative charge are destroyed.

Application

The range of application of emulsions in the industry is very wide. In particular, the compounds are used:

1. In the production of margarine and oil.
2. In soap making.
3. In the manufacture of materials from natural rubber.
4. In construction. For example, bitumen emulsion is a non-flammable compound.
5. In agriculture: pesticides are various preparations that destroy pests of plants.
6. For medical purposes: manufacturing of various medicines, ointments, cosmetics.
7. In painting, various emulsion paints are used.
8. Cosmetics for hair, emulsions, protecting the hair surface when staining. For example, a developing emulsion (this is an oxidizer for paint).
9. In the oil industry , a mixture of water and oil is used, in which the dispersion of one phase of the liquid into another takes place by the smallest droplets - globules.