Permeability (solid)
Permeability ( Latin : permeare “to let through”, from Latin: per “through”, and Latin: meare “to pass”) denotes the property of solids to allow gases and / or liquids to pass. It is used in some areas, e.g. B. the petroleum industry, indicated in Darcy .
In the chemistry and the biology is in the solid bodies whose permeability ( permeability ) is considered generally to membranes .
If the permeability of the solid differs for different substances (e.g. different gases or dissolved substances and solvents), one speaks of semipermeability or selective permeability . In technology, this property is used in dialysis and accumulators , for example . The reverse osmosis uses - for example, in seawater desalination - Selective permeability. Due to the diffusion of particles dissolved in the liquid phase, an osmotic pressure builds up in a semipermeable membrane .
In the case of transmembrane fluid transport in living beings, the membrane permeability determines the extent of the oncotic pressure and the hydrostatic pressure .
If there is no permeability, one speaks of impermeability. An unselective permeability (permeability for all substances) is called omnipermeability ( Latin : omni "whole, everyone, everything"), e.g. B. in the primary cell wall of plants . This is a permeable framework made of cellulose , cellulosans and pectin , under which a semipermeable cell membrane lies.
A physical unit for gas permeability through thin membranes is the barrer and for solids the perm .
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Individual evidence
- ↑ Hilmar Burchardi: Etiology and pathophysiology of acute respiratory failure (ARI). In: J. Kilian, H. Benzer, FW Ahnefeld (ed.): Basic principles of ventilation. Springer, Berlin a. a. 1991, ISBN 3-540-53078-9 , 2nd, unchanged edition, ibid. 1994, ISBN 3-540-57904-4 , pp. 47-91; here: pp. 64–66.
- ↑ Peter Schopfer, Axel Brennicke: Plant Physiology. Springer Berlin 2010. ISBN 9783827423528 . P. 54.