Definition of Donnan equilibrium in English:

Donnan equilibrium


  • The equilibrium reached between two ionic solutions separated by a semipermeable membrane when one or more of the kinds of ion present cannot pass through the membrane. The result is a difference in osmotic pressure and electrical potential between the solutions.

    • ‘In conclusion, we have established the role played by high-salt incubation and Donnan equilibrium in understanding the osmotic shock properties of viral capsids.’
    • ‘Again, this is due to the Donnan equilibrium effect, i.e., to the difference between inside and outside salt concentrations arising from the large density of fixed charge confined in the capsid.’
    • ‘Because the charge on hemoglobin, and therefore the magnitude of the Donnan equilibrium, changes with pH, the chloride concentration in the cells varies with pH.’
    • ‘In fact, if enough incubation buffer is added to the viruses, the concentration of multivalent ions can be made so small that they no longer contribute significantly to DNA charge neutralization nor thus to the Donnan equilibrium.’
    • ‘A time-honored way to take into account the difference between salt concentrations inside and outside the capsid during the incubation phase, due to Donnan equilibrium effects, is within the context of a cell model treatment.’


Early 20th century: named after Frederick G. Donnan (1870–1956), British physical chemist.


Donnan equilibrium

/ˌdänən ˌēkwəˈlibrēəm/