ELECTROOSMOSIS

From Big Medical Encyclopedia

ELECTROOSMOSIS (synonym electroendosmose) — the electrokinetic phenomenon representing the movement of a liquid phase (usually solution of electrolyte) along walls of a capillary tube or the surface of channels time in a cellular body under the influence of external electric field, Is data that the elsktroosmotichesky phenomena take place during the work of the cosecreting cells and eliminative organs at the person and animals. Believe that through a wall of proximal department of nephron along with usual osmosis also electroosmotic current of liquid is possible (see Urine, Kidneys). Phenomenon E. it is used in physical therapy (see) for introduction to an organism of medicinal substances through skin (see the Electrophoresis, a medicinal electrophoresis), in pharmaceutical industry for purification of colloid solutions of impurity (so-called electrodialysis), in the food industry for purification of glycerin, sugar syrups, gelatin, water, and also in the tanning textile industry. Phenomenon E. for the first time professor Moscow un-that F. F. Reyss described in 1807.

AA. it is caused by existence on the phase boundary of the double electric layer consisting from spatially of the divided and opposite loaded ions (see). Electric potential of an interface of phases, i.e. a mobile and motionless part of a double electric layer, call ζ-potential ((((((((((zeta-potential) or electrokinetic potential. Speed E. it is directly proportional to tension of external electric field and electroosmotic mobility of the system determined by the relation of the work of ζ-potential and dielectric permeability of solvent (see. Dielectric permeability) to viscosity (see) a liquid phase (Helmholtz's equation — Smolukhovsky). Speed E. does not depend on diameter and a form of a capillary or a structure of the porous membrane. The size of the stationary difference of pressure resulting E. (electroosmotic pressure), is in direct dependence on the size of ζ-potential, dielectric permeability of system, falling of electric potential along a fluid flow and it is inversely proportional the total area of cross-section of all holes of a membrane. At forced sloshing through membranes or capillaries the effect, the return E is possible.: emergence of potential difference between the ends of a capillary or the opposite surfaces of the porous membrane (so-called capacity of the current or course). The size of capacity of the current is directly proportional to electroosmotic mobility and electroosmotic pressure and is inversely proportional specific conductivity of solution (see. Solutions ).

At transfer of water against an osmotic gradient (see) in kidneys the phenomenon so naz, abnormal osmosis, i.e. transfer of water at simultaneous existence of osmotic and electric gradients is observed. Under natural conditions polarization of membranes can happen due to diffusion of ions through a time. If the electric gradient on absolute value exceeds osmotic, then transfer of water will be carried out in the direction of an electric gradient. Such phenomenon is called negative abnormal osmose. At positive abnormal osmosis transfer of liquid happens on an osmotic gradient to delay or acceleration at the expense of an electric gradient.

See also Osmotic pressure , Electrokinetic phenomena .

Bibliogr.: Gubanov N. I. and Utepbergenov A. A. Medical biophysics, page 205, M., 1978; Skorchelletti V. V. Theoretical electrochemistry, L., 1974; Schukin E. D., Pertsov A. V. and Amelina B. A. Colloid chemistry, page 173, 203, M., 1982.

V. A. Pekkel.

Яндекс.Метрика