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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 It might be outdated or ideologically biased.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 ?
The major force opposing ultrafiltration is glomerular capillary oncotic pressure, created by the gradient between the high concentration of plasma Proteins within the capillary and the almost protein-free ultrafiltrate in Bowman's space.
These results show for the first time in a human cell-derived system the importance of megalin in the uptake of 25O[HD.sub.3] from glomerular ultrafiltrate and extend that critical function to include the uptake and cellular response to 1[alpha],25[(OH).sub.2][D.sub.3].
During hyperglycemia, proximal tubules reabsorb more glucose from the glomerular ultrafiltrate [26].
In line with our hypothesis, the ultrafiltrate of conditioned medium significantly inhibited the BzATP-stimulated release of IL-1jS by LPS-primed U937 cells, whereas the ultrafiltrate of the control conditioned medium was ineffective (p = 0.016; n = 4 versus n = 5) (Figure 5(b)).
Separate aliquots of 300 [micro]L each were removed from the ultrafiltrate in the lower portion of the ultrafiltration device as well as from the control samples and transferred to clean screw-cap glass tubes.
It allows high volumes of ultrafiltrate using the filling liquid that can be administered before or after the filter.
Carraro et al., "Effect of haemodiafiltration with online regeneration of ultrafiltrate on oxidative stress in dialysis patients," Nephrology, Dialysis, Transplantation, vol.
The urea clearance index (Kt/V) was calculated using the following equation: Kt/V urea = -Ln(R- 0.008 x t) + [4-(3.5xR)]x UF/W, where R is the ratio of postdialysis and predialysis serum urea nitrogen content, t is the duration of dialysis (h), ultrafiltration (UF) is the ultrafiltrate amount (L), and W is the postdialysis body weight (kg).
The infusion rate of trisodium citrate and calcium gluconate as well as ultrafiltrate flow rate were recorded at 1, 2, 4, 6, 12, and 24 h after starting CVVH, respectively.
The percentage of desonide encapsulated was calculated by the difference between the total (content) and free desonide concentrations (ultrafiltrate) divided by the total desonide content and multiplied by 100 [20].
The process begins with the glomerulus, a heavily vascular structure of the nephron which creates an ultrafiltrate from the plasma.