Donnan potential is the difference in the

Galvani potential In electrochemistry, the Galvani potential (also called Galvani potential difference, or inner potential difference, Δφ, delta phi) is the electric potential difference between two points in the bulk of two phases. These phases can be two differ ...

s which appears as a result of

Donnan equilibrium Donnan can refer to: * Donnan (surname) * Donnan, Iowa, a community in the United States * Donnán of Eigg __NOTOC__ Saint Donnán of Eigg (also known as Donan;''The Oxford Dictionary of Saints'', p.135 died 17 April 617) was a Gaelic priest, ...

, named after Frederick G. Donnan, which refers to the distribution of

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

species between two ionic solutions separated by a

semipermeable membrane Semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by osmosis. The rate of passage depends on the pressure, concentration, and temperature of the molecule ...

or boundary.{{GoldBookRef , title=Donnan emf (Donnan potential) , file=MD01830 The boundary layer maintains an unequal distribution of ionic solute concentration by acting as a selective barrier to ionic

diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...

. Some species of ions may pass through the barrier while others may not. The solutions may be gels or

colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others exten ...

s as well as ionic liquids, and as such the phase boundary between gels or a gel and a liquid can also act as a selective barrier.

Electric potential The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is defined as the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in ...

arises between two solutions is called Donnan potential. Donnan equilibrium is prominent in the triphasic model for articular cartilage proposed by Mow and Ratcliffe, as well as in electrochemical

fuel cells A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...

and dialysis. The Donnan effect is extra osmotic pressure attributable to cations (Na⁺ and K⁺) attached to dissolved plasma proteins.

References

* Van C. Mow and Anthony Ratcliffe ''Basic Orthopedic Biomechanics'', 2nd Ed. Lippincott-Raven Publishers, Philadelphia, 1997 Physical chemistry Colloidal chemistry sl:Donnanovo ravnovesje

See also

References