Series a, containing papers of a mathematical and physical character 19051934. The potential distribution depends significantly on the thickness d of the surface charge layer when d less than or approximately equal to 1k. Experimental studies of the donnan equilibrium in physiological. Kondomenibrane potential and donnan potential ii which contain a uniunivalent symmetrical elec trolyte at different concentrations n1 and n11.
Frederick george donnan cbe frs frse 6 september 1870 16 december 1956 was an irish physical chemist who is known for his work on membrane equilibria, and commemorated in the donnan equilibrium describing ionic transport in cells. Pdf on jan 1, 2014, mazur iuliia and others published gibbsdonnan potential as a tool for membrane. The variation of electrical potential across a semipermeable membrane. The donnan potential appears as a result of donnan equilibrium, which refers to the distribution of ions between two ionic solutions separated by a semipermeable membrane or boundary. In a recent communication in nature july 17, 1943, p. The gibbsdonnan effect is a name for the behaviour of charged particles near a. Donnan potential appears as a result of donnan equilibrium, named after frederick g. Membrane potential and donnan potential sciencedirect. Donnan potential article about donnan potential by the. Donnan membrane technique dmt is developed and tested for determination of free anion concentrations. Time needed to reach the donnan membrane equilibrium depends on type of ions and the background. The donnan potential with the divalent counterion sulfate is expected to be.
Calculated donnan potential e d increase in membrane vesicles depending on salt concentration of. Donnan potential of rabbit skeletal muscle myofibrils i. Donnan potential and surface potential of a charged membrane. Pdf gibbsdonnan potential as a tool for membrane vesicles. Intheotherapproachit is regardedasthe surface potential, i. In polymer films carrying an excess of fixed charge the electrostatic penalty to bring ions of same charge from the bathing electrolyte into the film sets a membrane potential donnan potential across the film. The development of pressure across membranes in donnan. The donnan potential occurred in the cdp device with aem from ion flow to the capacitive electrode as cell potential.
Donnan potential and surface potential of a charged. Donnan equilibrium how is the potential difference caused. Donnan membrane equilibrium is not directly applicable to. A physical effect creating an electrical potential across a semipermeable membrane. On the other hand, a capacitive energy extraction donnan potential cdp device is a piece of equipment that extracts energy from the salinity gradient difference between river and sea water. One connects the salt solution b in the right cell to the reference cell h2 and the other connects the left side surface of the membrane to another reference cell h1. The variation of electrical potential across a semi.
This potential is responsible for the ionic permselectivity observed in polyelectrolyte membranes. Role of ionic charge density in donnan exclusion of. On the origin of the membrane potential arising across densely. Evaluation of the donnan model for polyelectrolytes using. He spent most of his career at university college london. Davis, in encyclopedia of separation science, 2000. By requiring continuity of the ion fluxes and the condition of electroneutrality, which is usually fulfilled outside a nmlength from a phase boundary, we can formulate.
Most importantly, the process can greatly reduce the volume of disposable sludge from thousands of water treatment plants. On the thermodynamic foundation of the donnan equation of state. The boundary layer maintains an unequal distribution of ionic solute concentration by acting as a selective barrier to ionic diffusion. Because of the presence of impermeant ion species on one side of the boundary, the concentrations of permeant ions are not the same on both sides of the boundary. Mass transfer characterization of donnan dialysis lake. The gibbsdonnan effect also known as the donnans effect, donnan law, donnan equilibrium, or gibbsdonnan equilibrium is a name for the behaviour of charged particles near a semipermeable membrane that sometimes fail to distribute evenly across the two sides of the membrane. Ion exchange membranes nernstplanck equation donnan equilibrium. Introduction donnan dialysis is a mass transfer process that utilizes ion exchange membranes to. The donnan potential varied from 80 to 40 mv as a function of gels crosslink density and the fraction of potassuim methacrylate monomer units. We have used electrochemical measurements to probe the. Donnan dialysis is a relatively new ion exchange process using ion exchange membranes to permit continuous operation. The donnan potential 6 is the name given to the interfacial potential difference that arises when certain ionic solutes cannot cross the interface between two immiscible electrolyte solutions while the remaining ions are free to move reversibly from one phase to the other 14, suppose, for example, that an ion r with a charge number z r has such a high partition coefficient p r. Donnan equilibrium an overview sciencedirect topics.
The donnan model, an equilibrium thermody namic description of charged media, is derived by requiring that the electrochemical potentials of the mobile ions. Donnan, which refers to the distribution of ion species between two ionic solutions separated by a semipermeable membrane or boundary. We assume that a membrane has charged surface layers of thickness d on both surfaces of the membrane, where the fixed charges are distributed at a uniform density n within the layers, and that these charged layers are permeable to electrolyte. Donnan potentials provide one constitutive relation per mobile ion. Donnan membrane technique dmt for anion measurement. Diese ungleichverteilung fuhrt zu einer potentialdifferenz donnanpotential oder. On the origin of the membrane potential arising across densely charged ion exchange membranes. A novel measurement method of donnan potential at an. Potential applications exist in many areas where traditional columnar ion exchange, requiring a regeneration cycle, is currently used. Request pdf on researchgate a donnan potential model for metal sorption onto bacillus subtilis in this study, we conducted electrophoretic mobility.
A literature study is presented on proposed theories for the origin of this membrane potential. How to model ionexchange membranes and donnan potentials. Donnan membrane equilibrium is not directly applicable to distributions of ions and water in gels or cells. Negative values of the potential increase with the decrease in crosslink density of the gel. The study of al speciation is of interest for the assessment of soil and water quality. The donnan potential at an interface between a membrane and salt solution was measured by using an apparatus as shown in fig.
Electrical neutrality is shown to be an extremely good approximation everywhere except close to. Donnan potential in hydrogels of polymethacrylic acid. The donnan potential 6is the name given to the interfacial potential. A model is presented for the electrical potential distribution across a charged biological membrane that is in equilibrium with an electrolyte solution. Full text get a printable copy pdf file of the complete article 791k, or click on a page image below to browse page by page. The donnan effect which is named after the british chemist frederick george donnan donnan 1911, 1995 is related to the presence of impermeant ions i. A short derivation of the nicadonnan model is presented to illustrate that the derivation is quite straightforward once it. In the true donnan equilibrium, all diffusible ions are in equilibrium across the membrane. The usual cause is the presence of a different charged substance that is unable to pass through the membrane.
The donnan membrane principle has the potential to recover the alum with high purity in a singlestep process and reuse it in the same plant or elsewhere as a coagulant. The donnan equilibrium relationship is derived from thermodynamics. A complete solution has been obtained for the distribution of ions and for the electrostatic potential in a simple donnan equilibrium, namely, where the membrane is permeable to two ions, but not to the third. On the thermodynamic foundation of the donnan equation of state this article has been downloaded from iopscience. Request pdf on jan 1, 2016, patrick fievet and others published donnan potential find, read and cite all the research you need on researchgate. The donnan model is proposed as the most convenient model. Download fulltext pdf download fulltext pdf exploiting donnan dialysis to enhance ammonia recovery in an electrochemical system article pdf available in chemical engineering journal april. The donnan membrane equilibrium is reached in 1 day for cl. The main objective of this study is to examine how the charge densities of four monovalent anionsfluoride f, chloride cl, bromide br, and nitrate no3influence their donnan charge exclusion by a charged nanofiltration nf membrane.