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(chemical engineering)
Separation of colloidal or very fine solid materials by filtration through microporous or semipermeable mediums.



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.


References in periodicals archive ?
Veronica Garcia, EMEA technical service and development manager, Dow Water & Process Solutions, said: "This type of pilot experiment does not usually last more than few weeks, and therefore the long duration of the DOW Ultrafiltration piloting emphasizes the company's long-term commitment to product development and continued research.
It demonstrates that inge ultrafiltration membrane technology delivers exceptional performance at large-scale for multiple industries in need of innovative, sustainable and cost-effective solutions for water filtration," emphasises Steis.
The CARRESS-HF trial randomized 188 affected patients who were diuretic responsive to a stepped pharmacologic care algorithm or to ultrafiltration at a rate of 200 mL/hr using the commercially available Aquadex System 100 device manufactured by CHF Solutions.
The introduction of the VCCTM into the Liqui-Flux[R] W10 Ultrafiltration Module allows system integrators to select from a variety of connection options to accommodate for the many space limitations and different water qualities faced in the field.
The company employs 85 and its products include ultrafiltration modules and rack designs for water treatment plants.
The agency has cleared several devices and accessories to achieve fluid removal through blood ultrafiltration, a process that removes excess water and solutes from a patient's blood.
The company modified a pulverizing machine to achieve the required specifications of the ultrafiltration cement," Mohammed Aziz Mohammed told Aswat al-Iraq.
Koch Membrane Systems has made available the Inducor and Inducor-G tubular modules for ultrafiltration of industrial process streams and wastewater.
The expanded Ultrafiltration Application and Product Guide contains additional product information and more protocols.