SOLS

From Big Medical Encyclopedia

SOLS (Latin sol[utio] solution) — the colloido-dispersion systems consisting of colloid particles (micelles) which are evenly distributed in a dispersion medium; such systems are some biological liquids.

Micelles in 3. are not connected with each other in spatial structures as it takes place in gels (see), and therefore 3. treat so-called svobodnodispersny colloid systems. Depending on aggregate state of a dispersion medium 3. divide into three classes — aerosols, lyosols and soliduszol.

Aerosols (see) represent suspensions firm (smoke and so forth) or liquid (fog and so forth) colloid particles in a gaseous dispersion medium, napr, in air.

Stability of aerosols generally is explained by existence of the electric charge, identical on a sign, arising on a surface of particles of an aerosol and interfering their association and, therefore, bystry subsidence.

Formation of aerosols in coal mines, at the flour-grinding and sugar enterprises can be a cause of explosion since a dispersed phase of these 3. possesses a big specific surface. As a result of the huge area of contact of particles of aerosols with air and small heat conductivity of aerosols processes of oxidation of their particles proceed with high speed that is followed by warming up of system and frequent explosion.

These explosions can be localized by addition to aerosols of some indifferent dust. In mines, e.g., suspend boxes with limy dust, edges gets enough sleep at local explosion and limits its further distribution. In the cities purification of free air of aerosols it is possible to make them coagulation under the influence of electric field of high tension before intake of dust and smoke in the atmosphere.

Aerosols are widely applied in military science (smoke screens and so forth), in agriculture and other fields of the national economy.

Great practical value has spraying of the concentrated aerosols of various disinfecting substances — insecticides (see), herbicides (see), etc. — at pest control (insects, fungi, weeds, microbes etc.).

During the kindling of fires in gardens over a certain ground creeping smoke which detains a thermolysis of the earth is formed. On particles of the aerosol shrouding trees there is an intensive condensation of water vapors, and at the same time vaporization heat is distinguished that protects plants from freezing.

Some aerosols can be unhealthy the person (see. Aerosols ). The aerosols containing particles of oxides of some metals (lead, zinc, etc.), silicon dioxide and so forth are very dangerous. These particles, getting into lungs, can become the reason of dangerous diseases — pneumoconiosis (see) and other diseases.

Aerosols are widely applied in medicine at treatment of respiratory diseases and lungs by means of inhalations by aerosols of various antibiotics and other medicinal substances (see. Aerosoltherapy ).

Lyosols (grech, lios liquid), called by also colloid solutions (see. Colloids ), are suspensions of gaseous, liquid or firm micelles in a fluid dispersion medium. Depending on the chemical nature of a dispersion medium lyosols subdivide into hydrosols, the petrolevils and, efirozol and etc. On the nature of interaction of micelles with a dispersion medium lyosols divide into two groups: on lyophobic and lyophilic 3., in particular on hydrophobic and hydrophilic 3., if a dispersion medium is water. To lyophobic 3. 3 belong, e.g. metals, oxides, hydroxides, sulfides of metals, graphite, sulfur in water and other liquids. These systems have small aggregate stability, their micelles easily combine in larger units under the influence of various factors, napr, at addition of trace amounts of electrolytes (see. Coagulation ). Major factor of stability lyophobic 3. existence of the colloid particles identical on a sign of electric charges is. Examples lyophilic 3. colloid solutions can serve [[ | washed SOAPS ]] (see), detergents (see), etc. Micelles lyophilic 3. owing to their considerable interaction with molecules of a dispersion medium of a solvatirovana (see. Solvation ). Existence of solvation shells at micelles is one of major factors of aggregate stability lyophilic 3. Earlier to lyophilic 3. carried also solutions high-molecular compounds (see). However the last, being homogeneous systems, significantly differ on the properties from 3., representing heterogeneous systems.

Soliduszoli represent firm 3., sols with a solid dispersion medium. Examples such 3. some metal alloys (cast iron, steel) can serve, milk and ruby flew down, gemstones (the ruby, sapphire, fell down, alexandrite, etc.).

Colloid particles in aerosols and lyosols are in a condition of heavy Brownian motion owing to what these 3. have a number of the properties inherent in true solutions. So, e.g., for aero - and lyosols the phenomena of diffusion, and for lyosols, besides, of the phenomenon of osmosis, osmotic pressure, fall of temperature of freezing, etc. are found. However these phenomena for 3. are quantitatively expressed in much smaller degree, than for true solutions since concentration of micelles in lyosols is small.

3. many substances are widely used in various industries: rubber, textile, paint and varnish, oil, pharmaceutical, etc.

See also Disperse systems , Coagulation , Colloid protection , Colloid pharmaceuticals .


Bibliography Voyutsky S. S. Course of colloid chemistry, M., 1975, bibliogr.

V. Mishin.

Яндекс.Метрика