Editing Ultrafiltration (section)

{{Short description|Filtration by force through a semipermeable membrane}}
{{For|ultrafiltration in biology|Ultrafiltration (renal)}}
'''Ultrafiltration''' ('''UF''') is a variety of [[Membrane technology|membrane filtration]] in which forces such as [[pressure]] or [[concentration gradient]]s lead to a separation through a [[semipermeable membrane]]. [[Suspended solids]] and [[solutes]] of high [[molecular weight]] are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the [[permeation|permeate]] (filtrate). This [[separation process]] is used in industry and research for purifying and concentrating macromolecular (10<sup>3</sup>–10<sup>6</sup> [[Atomic mass unit|Da]]) solutions, especially [[protein]] solutions.

Ultrafiltration is not fundamentally different from [[microfiltration]]. Both of these are separate based on size exclusion or particle capture. It is fundamentally different from [[membrane gas separation]], which separate based on different amounts of [[absorption (chemistry)|absorption]] and different rates of [[diffusion]]. Ultrafiltration membranes are defined by the [[molecular weight cut-off]] (MWCO) of the membrane used. Ultrafiltration is applied in [[Cross-flow filtration|cross-flow]] or [[Filtration|dead-end mode]].