Osmosis abnormal

E. Grim and K. Sollner, The contributions of normal and abnormal osmosis to the osmotic effects arising across charged membranes with solutions of electrolytes, J Gen. Physiol., 1957, 40, 887. 

Osmosis might be called the principle of the prune. The skin of the prune acts as a membrane permeable to water. The sugars in the prune are the solutes. Water diffuses through the skin and the fruit swells until the skin ruptures or becomes leaky. Only rarely are plant and animal membranes strictly semipermeable. Frequently, their function in the organism requires that they pass other materials, as well as water. Medicinally, the osmotic effect is utilized in, for example, the prescription of a salt-free diet in some cases of abnormally high fluid retention by the body. 

Soil has long been considered as a chemical system due to its semipermeability to chemicals, bioactivity, interactions with chemicals, and so on. As a result, soil has been idealized as a leaky semipermeable membrane in chemical osmosis to explain various abnormal transport phenomena of water and chemicals in soil (Hanshaw, 1972 Marine and Fritz, 1981 Fritz and Marine, 1983 Yeung, 1990 Keijzer, Kleingeld, and Loch, 1999) as a Donnan membrane (Donnan, 1924) to examine the influences of soil type, water content, electrolyte concentration, and the cation and anion distribution in pore fluid on electroosmotic flow of fluid in soil (Gray and Mitchell, 1967) as a bioreactor to evaluate the impact of oxygen transfer on efficiency of bioremediation (Woo and Park, 1997) and so on. 

Fig. 16. C -potentials of pyrex glass evaluated from electro-osmosis ( ) and from streaming potentials (x) as a function of the concentration of electrolyte. The data for KNO3 derived from electro-osmosis should probably be disregarded owing to a different treatment of the capillary as in this case the water value (c 0) is abnormally high ...

A phenomenon that without a doubt is connected with electro-osmosis is the abnormal osmosis, known already to Graham, but especially investigated by Loeb When two solutions of different concentrations are separated by a semi-permeable membrane, the normal osmotic movement is a transport of the solvent from the more dilute to the more concentrated phase. In many cases however, if the membrane is not rigorously impermeable to the solute a transport of liquid in the opposite direction is observed. 

This ti ansport may be explained as an electro-osmotic flow of the liquid through the pores of the membrane under the influence of the potential difference (diffusion potential) between the two liquid phases. That this explanation hits the nail on the head was demonstrated by Loeb, who showed, that, for a given membrane, the influence of electrolytes on abnormal osmosis and on electro-osmosis was similar if not identical. 

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