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(chemical engineering)
Separation of colloidal or very fine solid materials by filtration through microporous or semipermeable mediums.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.


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


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Auburn, New York-based Cayuga Milk Ingredients previously exported ultrafiltered milk to Canada, before Class 7 made the company's prices uncompetitive.
The new facility, scheduled to begin operations in the first quarter of 2020, will produce fairlife Ultrafiltered Milk in Fat Free, 2% White, 2% Chocolate and Whole (3.25%) White in 1.5 L PET bottles; and 2% White and 2% Chocolate in 240 mL PET bottles.
The reaction mixture was ultrafiltered (3,000 g; 4[degrees]C) through Amicon Ultra 0.5 mL 100 K MWCO (Merck Millipore, Merck KGaA, Darmstadt, Germany) at least three times with 10 mM MES pH 5.5 and two times with 10 mM PBS pH 7.4.
The enzyme supernatant concentrated by ammonium sulphate precipitation was ultrafiltered using Amicon 3 kDa cut off centrifugal filter unit (Millipore, USA) and the amount of protein was estimated using BSA as standard (15).
While Marcos' dialysis in Hawaii diffused and ultrafiltered water and toxic wastes in his blood, the Filipinos were also doing a cleansing process or catharsis as a nation.
The supernatant was ultrafiltered to remove cells and cellular debris and sucrose gradient centrifugation was performed to remove contamination with other protein complexes (Figure 1(a)).
Patients were ultrafiltered daily until they achieved a target BNP level of less than 500 pg/ml (maximum 51 per session).
All DNA hydrolysates were ultrafiltered using Ultrafree-MC filter units (cut-off of 5000 Da).
Mehaia, "Manufacture of fresh soft white cheese (Domiati-type) from ultrafiltered goats' milk," Food Chemistry, vol.
Permeate was ultrafiltered through a 30 kDa cut-off membrane (Millipore, Billerica, MA, USA), until reaching a final volume of 20 mL.
Allegri et al., "Calcium oxalate crystallization in untreated urine, centrifuged and filtered urine and ultrafiltered urine," Clinical Chemistry and Laboratory Medicine, vol.