Ultrafiltration

ultrafiltration

[¦əl·trə·fil′trā·shən] (chemical engineering) Separation of colloidal or very fine solid materials by filtration through microporous or semipermeable mediums.

Ultrafiltration

the forcing of a liquid through a semipermeable membrane, a membrane that allows small molecules and ions to pass but not macromolecules and colloidal particles. The ultrafiltration of solutions containing molecules of high-molecular-weight compounds, unlike the ultrafiltration of sols, is sometimes called molecular filtration. Ultrafiltration may be regarded as dialysis under pressure or as reverse osmosis if the membrane lets only molecules of solvent pass through. In the latter case, often called hyperfiltration, the pressure should exceed the osmotic pressure of the solution.

Membranes for ultrafilters, usually in the form of plates (sheets) or cylindrical holders (“candles”), are primarily made of artificial and synthetic polymers, such as esters of cellulose, and polyamides. Sometimes they are made from microporous inorganic materials and from products of animal origin. The size of particles (molecules) passing through the membrane varies between several microns and hundredths of a micron. The separating capacity of a membrane depends on its structure and physico-chemical properties, as well as on pressure, temperature, the composition of the filtered liquid, and other external factors.

As a method of concentrating, purifying, and fractionating highly dispersed systems and multicomponent solutions, ultrafiltration is widely used in laboratory work, medicine, and industry. For example, it is used to remove ionic and nonionic impurities from water, organic solvents, liquid fuels, and lubricating oils. It is also used to separate into individual components complex mixtures of proteins, alkaloids, and other substances, isolate enzymes, vitamins, and viruses, and sterilize liquids designated for medical and pharmaceutical purposes. In addition, it is used in dispersion analysis and microbiological analysis and to analyze air and water for pollution with industrial and household wastes.

REFERENCE

Dytnerskii, Iu. I. Membrannyeprotsessy razdeleniia zhidkikh smesei. Moscow, 1975.

L. A. SHITS

ultrafiltration

[ul″trah-fil-tra´shun] filtration through filters with minute pores, thus allowing the separation of extremely minute particles. It occurs naturally, as in the filtration of plasma at the capillary membrane, and is also performed clinically and in the laboratory, such as in hemodialysis, where it involves the bulk movement of solute and solvent across the membrane down pressure gradients and is usually performed under pressure to accelerate the process.

ul·tra·fil·tra·tion

(ŭl'tră-fil-trā'shŭn), Filtration through a semipermeable membrane or any filter that separates colloid solutions from crystalloids or separates particles of different size in a colloid mixture.

ul·tra·fil·tra·tion

(ŭl'tră-fil-trā'shŭn) Filtration through a semipermeable membrane or any filter that separates colloid solutions from crystalloids or separates particles of different size in a colloid mixture.

ultrafiltration

Filtration through a SEMIPERMEABLE MEMBRANE that allows only the passage of small molecules, such as those smaller than protein molecules.

ultrafiltration

the process by which small molecules and ions are separated from larger molecules in blood to form the INTERSTITIAL FLUID or in the kidney to form the renal filtrate.

ultrafiltration

One of the mechanisms that produce aqueous humour from blood plasma into the ciliary epithelium of the ciliary processes. This mechanism takes advantage of the natural pressure gradient between the capillary vascular pressure and intraocular aqueous pressure, to drive fluid into the eye. Ultrafiltration is one of three physiological processes that create aqueous fluid, the others being active transport and diffusion. See ciliary body; diffusion; active transport aqueous rate of outflow humour.

单词	ultrafiltration
释义	ultrafiltration ul·tra·fil·tra·tion U0010400 (ŭl′trə-fĭl-trā′shən)n. The filtration of a solution or colloidal substance through a semipermeable medium that allows only the passage of small molecules. Translations Ultrafiltration ultrafiltration [¦əl·trə·fil′trā·shən] (chemical engineering) Separation of colloidal or very fine solid materials by filtration through microporous or semipermeable mediums. Ultrafiltration the forcing of a liquid through a semipermeable membrane, a membrane that allows small molecules and ions to pass but not macromolecules and colloidal particles. The ultrafiltration of solutions containing molecules of high-molecular-weight compounds, unlike the ultrafiltration of sols, is sometimes called molecular filtration. Ultrafiltration may be regarded as dialysis under pressure or as reverse osmosis if the membrane lets only molecules of solvent pass through. In the latter case, often called hyperfiltration, the pressure should exceed the osmotic pressure of the solution. Membranes for ultrafilters, usually in the form of plates (sheets) or cylindrical holders (“candles”), are primarily made of artificial and synthetic polymers, such as esters of cellulose, and polyamides. Sometimes they are made from microporous inorganic materials and from products of animal origin. The size of particles (molecules) passing through the membrane varies between several microns and hundredths of a micron. The separating capacity of a membrane depends on its structure and physico-chemical properties, as well as on pressure, temperature, the composition of the filtered liquid, and other external factors. As a method of concentrating, purifying, and fractionating highly dispersed systems and multicomponent solutions, ultrafiltration is widely used in laboratory work, medicine, and industry. For example, it is used to remove ionic and nonionic impurities from water, organic solvents, liquid fuels, and lubricating oils. It is also used to separate into individual components complex mixtures of proteins, alkaloids, and other substances, isolate enzymes, vitamins, and viruses, and sterilize liquids designated for medical and pharmaceutical purposes. In addition, it is used in dispersion analysis and microbiological analysis and to analyze air and water for pollution with industrial and household wastes. REFERENCE Dytnerskii, Iu. I. Membrannyeprotsessy razdeleniia zhidkikh smesei. Moscow, 1975. L. A. SHITS ultrafiltration ultrafiltration [ul″trah-fil-tra´shun] filtration through filters with minute pores, thus allowing the separation of extremely minute particles. It occurs naturally, as in the filtration of plasma at the capillary membrane, and is also performed clinically and in the laboratory, such as in hemodialysis, where it involves the bulk movement of solute and solvent across the membrane down pressure gradients and is usually performed under pressure to accelerate the process. ul·tra·fil·tra·tion (ŭl'tră-fil-trā'shŭn), Filtration through a semipermeable membrane or any filter that separates colloid solutions from crystalloids or separates particles of different size in a colloid mixture. ul·tra·fil·tra·tion (ŭl'tră-fil-trā'shŭn) Filtration through a semipermeable membrane or any filter that separates colloid solutions from crystalloids or separates particles of different size in a colloid mixture. ultrafiltration Filtration through a SEMIPERMEABLE MEMBRANE that allows only the passage of small molecules, such as those smaller than protein molecules. ultrafiltration the process by which small molecules and ions are separated from larger molecules in blood to form the INTERSTITIAL FLUID or in the kidney to form the renal filtrate. ultrafiltration One of the mechanisms that produce aqueous humour from blood plasma into the ciliary epithelium of the ciliary processes. This mechanism takes advantage of the natural pressure gradient between the capillary vascular pressure and intraocular aqueous pressure, to drive fluid into the eye. Ultrafiltration is one of three physiological processes that create aqueous fluid, the others being active transport and diffusion. See ciliary body; diffusion; active transport aqueous rate of outflow humour. See UF See UF
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