Donnan equilibrium refers to the distribution of ion species between two ionic solutions separated by a semipermeable membrane or boundary. The boundary layer maintains an unequal distribution of ionic solute concentration by acting as a selective barrier to ionic diffusion. Some species of ions may pass through the barrier while others may not. The solutions may be gels or colloids 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. An ion is an atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss or addition of one or more electrons. ... Dissolving table salt in water In chemistry, a solution is a homogeneous mixture composed of one or more substances, known as solutes, dissolved in another substance, known as a solvent. ... Scheme of semipermeable membrane during hemodialysis, where red is blood, blue is the dialysing fluid, and yellow is the membrane. ... This article or section does not cite its references or sources. ... A gel (from the lat. ... In general, a colloid or colloidal dispersion is a substance with components of one or two phases, a type of mixture intermediate between homogeneous solution and heterogeneous mixture with properties also intermediate between a solution and a mixture. ...

Donnan equilibrium is prominent in the triphasic model for articular cartilage proposed by Mow and Ratcliffe, as well as in electrochemical fuel cells and dialysis. Cartilage is a type of dense connective tissue. ... A fuel cell is an electrochemical device similar to a battery, but differing from the latter in that it is designed for continuous replenishment of the reactants consumed; i. ... In medicine, dialysis is a type of renal replacement therapy which is used to provide an artificial replacement for lost kidney function due to renal failure. ...

The Donnan effect is extra osmotic pressure attributable to cations (Na and K) attached to disolved plasma proteins

See also

• Chemical equilibrium
• Nernst equation

Chemical equilibrium is the state in which the concentrations of the reactants and products have no net change over time. ... In electrochemistry, the Nernst equation gives the electrode potential (E), relative to the standard electrode potential, (E0), of the electrode couple or, equivalently, of the half cells of a battery. ...

References

• IUPAC Compendium of Chemical Terminology 2nd Edition (1997)
• Van C. Mow and Anthony Ratcliffe Basic Orthopedic Biomechanics, 2nd Ed. Lippincott-Raven Publishers, Philadelphia, 1997