Ultrafiltration

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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

References in periodicals archive ?
In order for honey to be ultrafiltered, it must first be watered down.
The digests were further transferred to a new tube, ultrafiltered by 10 kDa Microcon filtration device (Sartorius, Germany) to remove large molecules, and lyophilized to dryness.
Development of proteolysis in ultrafiltered Turkish white-brined cheese (Urfa type)--effect of brine concentration.
BSA with a MW of 67,000 g/mol, bought from Fluka and PEG with MWs of 20,000 and 35,000 g/mol, purchased from PH EUR, have been ultrafiltered.
For the matrix fluids, ultrafiltered water (Barnstead NANOpure system, Dubuque, IA) was combined with either 2P (98 % nominal purity from Sigma Aldrich, St.
Ultrafiltered gelatin was assessed for purity prior to analysis using standard % gelatin yield, %N, %C and C:N quality assurance parameters (Table 1).
Coagulation of milk enriched with ultrafiltered or diafiltered microfiltered milk retentate powders.
1989) Serum immunoglobulin levels and naturally occurring antibodies against carbohydrate antigens in germ-free BALB/c mice fed chemically defined ultrafiltered diet.
For reasons not fully understood, ultrafiltered meads tend to have faster, more dependable fermentations.
Then, the researchers ultrafiltered and spray-dried the pasteurized fat-separated whey to 34% and 80% whey protein concentrate.
mutans UA 159 cultivated in ultrafiltered culture media containing tryptone and yeast extract (UTYEB) supplemented with 1% glucose.