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 ?
The ultrafiltrate flow rate was the sum of the dehydration rate by CVVH and the infusion rate of replacement fluid, bicarbonate-buffered fluids, citrate, and calcium.
Effect of haemodiafiltration with online regeneration of ultrafiltrate on oxidative stress in dialysis patients.
5 30K device with the same type of tubes as before (EMD Millipore Corporation, Billerica, MA, USA), and the ultrafiltrate was measured for the small PRL using electrochemiluminescence immunoassay method by Cobas E411 analyzer (Roche Diagnostics, Indianapolis, USA).
The flow rate of the dialysate was 500 ml/hour and the flow rates of replacement fluid and ultrafiltrate were equal and set at 500 ml/hour; these rates were again identical to the common and practical rates that are covered by Japanese social health insurance.
More complex methods involving the measurement of chloride in serum and its ultrafiltrate or the measurement of serum osmolality before and after dilution have been proposed.
This hypothesis has been questioned as the flow of ultrafiltrate was measured to be so rapid as to prohibit crystal aggregation, thus preventing crystals large enough to occlude the tubular lumen.
The ultrafiltrate was stored in 5-ml plastic solution tubes at -80[degrees]C until needed.
Post-translational VDR modification is induced by substances from uremic plasma ultrafiltrate that reacts covalently with VDR at or near the DNA binding domain and thus disrupting VDR-RXR binding of DNA.
Fractionation technology from Digilab Biovision GmbH, Hanover, Germany, was adopted for the isolation of low molecular weight peptides (typically <15,000 Da) from human plasma ultrafiltrate.
CVVH circulates blood through a haemofilter and yields an ultrafiltrate solution with the composition of plasma water containing low molecular weight non-protein bound solutes.
Henkel Autophoretic Process Generic electropaint process 1 Pick Up Pick Up 2 Space for extra pickle stage Space for extra pickle stage 3 Acid Pickle Acid Pickle 4 First Rinse First Rinse 5 Dip Clean Dip Clean 6 Spray Clean Spray Clean 7 'Warm' Rinse Second Rinse 8 Deionised Water Rinse Deionised Water Rinse 9 Autophoretic Dip Dip Activator 10 Rinse Dip Zinc Phosphate 11 Reactive Rinse Fourth rinse 12 Transfer Fifth Rinse 13 Three stage Oven Catophoretic Paint Dip 14 'Cross' Transfer Ultrafiltrate Dip Rinse 15 Deionised Water Rinse 16 Transfer 17 Four stage Oven 18 'Cross' Transfer Above: Note the process route is not linear, but starts at dip clean, first rinse, acid pickle, first rinse dip clean, spray clean in both options.