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The Gouy-Chapman theory of the electric double layer is applied to the calculation of the interaction energy of a charged surface film and a solid surface of opposite charge immersed in a solution of electrolyte. This model is found to account for the decrease in efficiency of precipitate flotation and adsorbing colloid flotation which is observed when ionic strength is increased. The Gouy-Chapman theory is also used to predict the existence of analogs to the phenomena of electroosmotic flow and streaming potential in foams and surface films.

Henry's classic theory for the electrophoresis of a single isolated sphere is extended analytically to cover the more practical problem of the electrophoresis of a swarm of identical, dielectric, spherical particles. The effects of interaction of the individual particles and their associated electric fields are taken into explicit account by employing a fundamental cell-model representation which is known to provide good predictions for the motion of a swarm of spheres within a fluid in the absence of electrical effects. For thin double layers, the electrophoretic velocity of (or the electroosmotic velocity within) a swarm of identical dielectric spheres is shown to be invariant, practically speaking, with respect to the void fraction of the swarm. However, as the double layer thickness increases the electrophoretic (electroosmotic) velocity decreases sharply and becomes strongly dependent on the void fraction. The computed results provide theoretical justification for Smoluchowski's widely quoted approximate result for electroosmotic flow within porous media of arbitrary pore geometry.

The development of electrodialysis is described with its use as a practical process in demineralizing and concentrating solutions of electrolytes. The applications and basic types of ion-exchange membranes for use in electrodialysis are discussed. Membrane properties such as electrical resistance, permselectivity, ionic capacity, solvent transfer and chemical resistance are given in detail as being particularly important in characterizing electrodialytic properties of ion-exchange membranes. Demineralization of cheese whey is dealt with fully and various problems and techniques discussed. Variants of electrodialysis - transport depletion, ion substitution and electro osmosis are also given. (Editor's summary)

An attempt was made to induce transport of water in sections of roots of Lens by applying electrical potentials. The results support the conclusion that the observed water flows were moved electro-osmotically. With currents between 3 and 50 microamperes, the efficiency of water movement was found to be of the order of 20 to 80 water moles per faraday in living roots and four to six times more in killed roots. The highest efficiency coinciding with the best conductivity was observed in the zone of elongation. An asymmetry of flow upon reversal of the direction of the current was found which appeared to be linked to an asymmetry of both apparatus and plant material.

A critical comparison of the electroosmotic flow rate and stream current over a wide range of solid concentrations was made using softwood bleached sulfite, cotton, cellulose acetate, and glass fibers in the presence of 2.5 × 10−5 N KCl. ξE showed a good agreement with ξS with the sulfite and glass fibers, but was lower than ξS for the cotton and acetate fibers. It was also found that the electroosmotic flow rate F was not directly proportional to the applied potential at low values of F. It was shown conclusively that the discrepancy was due to the unexpectedly large effect of the air bubble in the capillary flowmeter in resisting electroosmotic flow. When allowance is made for the bubble effect, F is independent of the applied potential and ξE and ξS agree within 1%. A series of measurements of electroosmotic pressures is reported. With the glass fibers, agreement between ξE and ξS was obtained at solid fractions at low as 0.009, in a region where the resistance to flow of fluid approaches the Stokes resistance of single particles. This is taken to be evidence of an equivalence of the electroosmotic, electrophoretic, and streaming functions.

Stream potential, electro-osmotic, and permeability measurements were made on cotton pads in the presence of distilled water. Several sources of irreproducibility have been eliminated from the usual experimental methods of measuring the ζ-potential. Uniform packing of the pad has been shown to be important. The Briggs method of evaluating the "pore factor" by electrical conductivity measurements was found to be invalid. An alternative method of determining the factor is proposed, based on an assumed value for the pore orientation factor and an indirectly measured value of the swollen specific volume of the fibers. The latter can in principle be determined by measuring one of the electrokinetic functions or the permeability coefficient over a range of pad concentrations. When pads of different concentration were used, the stream potential, electro-osmotic, and permeability functions were found to vary erratically in the same manner, an effect which, it has been concluded, originates from lack of uniform packing of the pad. The electro-osmotic measurements were found to require a large correction for capillary electro-osmosis, a source of error which has been overlooked by other workers. The ratio of the ζ-potential calculated from electro-osmosis to that from the stream potential was greater than unity and increased with increase in pad concentration.

To a fixed‐charge lattice model previously employed to investigate ionic mobility in a system with no bulk flow, we have added crude hydrodynamic boundary conditions which make possible a solution of the appropriate Navier—Stokes equation in the presence of an external electric field. The resulting flow, electro‐osmosis, is strongly dependent on the concentration of neutral salt present, attaining a maximum in the absence of salts. The gradual transition from Poisseuille parabolic flow to ``plug'' flow as salt concentration or fixed‐charge density increases is explicitly demonstrated for the model.

The ability of the Canalco Model CF-3 electro-osmosis (EO) apparatus to concentrate viruses from artificially seeded distilled water was improved. Modification of the physical arrangement of the equipment allowed for a 10–25 fold increase in concentration efficiency and a concomitant decrease in the process time. The major improvements involved modifications of the cell arrangement (which increased the membrane transport area), a change in the salt replenishing solution and the use of different membranes of higher flux. Viruses concentrated by E0 from seeded tap water resulted in lower recoveries when compared to distilled water. The lower yields were probably due to instability or aggregation of the agents in the menstruum and not directly related to the physical apparatus. Under the conditions used, one could detect virus at levels as low as 0.01 plaque forming units (PFU) per ml of initial input. The efficacy of a modification of the Canalco forced-flow electrophoretic (FFE) system was also ev...

Elektrokinetic effects in diaphragms are treated with the aid of a model consisting of a network of capillaries. With negligible surface conductance or when all capillaries have equal cross-sections the streaming-potential E/P and the electro osmotic flow V/I are both equal to ϵζ/4πη. R. C where R and C are the resistance and the capacity of conductance of the network. In the presence of surface conductance, and for unequal cross-sections of the capillaries, the proportionality constant between E/P or V/I and RC may be either smaller or greater than ϵζ/4πη depending on the detailed structure of the diaphragm. The first case is the usual one. For a value larger than ϵζ/4πη rather exceptional conditions have to be fulfilled.

When electro-osmosis is observed through a substance (or tissue) certain inferences can be made about the fine structure of the substance. These include the presence of a zeta potential whose sign is the same as that of the electrode towards which water moves, and the presence of interstices or channels large enough to allow ions to move through them and to sweep along more water molecules than those carried as hydration shells. Channels too large may permit both positive and negative ions to move or at least allow a counter flow of water to reduce the net (observable) movement of water molecules.

Experimental studies on the thermo-osmosis, electro-osmosis and electrophoresis of water carried out by the authors are reviewed. The flow rate of water through swollen cellophane membranes is found to depend on temperature difference in a linear manner up to Δ T = 25°C. Thermo-osmosis occurs only if the pore size of the membrane is greater than the molecular diameter and is comparable with the mean free path of the molecules. Electro-osmotic flow of water through G4 pyrex sinter is linearly dependent on potential difference only up to ΔΦ = 70 volts. The results may be useful in designing suitable electrodialyzers for the purification of water. The electrophoretic velocity of glass particles in water has been found to vary linearly with applied potential difference up to ΔΦ = 160 volts. The results are also discussed in the light of the theory of thermodynamics of irreversible processes.

Electro-osmosis could occur through a composite membrane consisting of a porous wall with a continuous lining of lipid in which water and ions are soluble; pores right through are not necessary. The available information about the hydraulic permeability, the diffusional permeability and the conductance of the cell membrane in Nitella can be explained without making any unreasonable assumptions as to the properties of the wall and the lipid lining.

If the principle of electro-osmosis is applied as a method of reducing skin friction between a metal wall and a mass of clay, the operation is simpler as compared with the conventional methods.Moreover, this method is convenient, because the same equipment can be simultaneously used for not only reducing but also increasing the skin friction.H. K. S. Ph. Begemann suggested already that this method could be succesefully applied to the pile-driving and the sinking of pite foundation.But he did not present the mechanism of reducing skin friction, nor a possibility of effectively utilizing this method for various types of soil.On the mechanism of decreasing skin friction, the author indicated that the electro physical effects consists of two reducing effects; the bubble effect due to electrolysis of water and the letting and accumlating effects due to development of osmotic water around the negative electrode. Futhermore, the author treated experimentally the practical application of this method to the various conditions of samples.As a general result, it has been discovered that there is a possibility of effectively utilizing this method to the foundation work in clay soil having high adhesion.

Transient electro‐osmosis of water in glass capillary tubes is treated analytically. The usual selective ion adsorption mechanism is assumed. The analysis is restricted to tube radii greater than about 3 × 10−5 m for which the effects of fluid compressibility and electrical capacitance and inductance are negligible. The problem considered is the transient response of the system to a step change in either pressure or voltage under various external loading conditions. The resulting time histories of the induced force (voltage or pressure) and the fluid flow and electrical current are solved for. A Laplace transform technique is employed. Coupling coefficients are established in the Laplace domain relating the electrical current and fluid flow rate to the electric field and pressure gradient. The cross‐coupling coefficients are shown to obey the reciprocal relations for nonsteady‐state irreversible processes.

Electro-osmotic velocity, electro-osmotic pressure and rate of permeation for acetone/Pyrex sinters are reported in this paper. The range of validity of linear phenomenological relations has been experimentally ascertained. L12 is found to be constant up to potential differences of about 440 V. The second-order coefficient L112 has been estimated from measurements of electro-osmotic pressure and the rate of permeation in the presence of pressure and potential gradients. Streaming potential measurements are also recorded and L21 has been found to be constant up to pressure differences of 100 cm of acetone. Onsager's reciprocal relation has been verified.

By measuring the number of water molecules per ion which were moved electro-osmotically through cells of Nitella translucens and N. flexilis it has been shown that a significant difference existed between samples of these species in 1965. In each species the electro-osmotic efficiency was greater with Na+ than with K+. Also io-4 to io~5 M IAA tended to decrease electro-osmotic efficiencies while IAA, after 30 min. treatment, produced a significant increase in water flow into the treated end of a living cell. Calculations based on this work suggest that about io8-io9 pore sites per cm2 exist on the surface membranes for Na+ or K+ ion transport.

The specific conductance and electroosmotic permeability of a homogeneous cation-exchange membrane are reported as functions of composition and concentration of the ambient solutions of NaBr, CsBr, and SrBr2 and their mixtures at 25°C. The equivalent conductances of the ions in the membrane were evaluated by using transport numbers determined earlier (see Part I). The conductances of the counterions were found to be greater and of the coions smaller than calculated from their tracer diffusion coefficients in the membrane. This was attributed mainly to interactions between the ionic currents and the electroosmotic stream. When the membrane contained only one kind of counterion about 60% of the mean electroosmotic stream velocity had to be added to the diffusional mobility to obtain the electrical mobility of the counterions. At low concentrations the coions were scarcely retarded by the electroosmotic stream. At high concentrations the retardation was greater than the electroosmotic stream velocity and this was attributed to an additional retardation of the coions caused by the counterions moving in the opposite direction. When the membrane contained a mixture of counterions the thermodynamically preferred species derived less assistance in conduction from the electroosmotic stream than did the nonpreferred species. This was attributed to the preferred ions occupying on average the denser regions in the membrane where the electroosmosis is less strong.

The electroosmotic flow of water was investigated in homogeneous systems of kaolinite clay, as a function of the adsorbed counter-ion and the water content of the systems. The results were compared with the predictions of various theories of electroosmotic flow. Although the nature of the counter-ion affected the rate and the direction of flow, no simple interpretation in terms of ion hydration was warranted. The relation of electroosmotic flow to hydraulic permeability at various water contents was compatible with the Helmholtz-Smoluchowski electrokinetic equations. The equations of Schmid for fine-pored systems were not applicable.

General expressions for electrokinetic phenomena of relevance in biology are derived using the methods of irreversible thermodynamics and Onsager coefficients, not only for a Helmholtz-Smoluchowski model but also for a factional model and the model of Schmid. These last two models would seem to be more appropriate for biological cell membranes.Some applications of these expressions to plant physiology include the following: the pressure contribution of electro-osmosis to the turgor of Nitella or Chara cells is found to be negligible; the power used by an electro-osmotic pump can never be less than that used by a pressure mechanism; electro-osmosis may account for the present discrepancies between calculations of membrane conductance using tracer ions fluxes and those using applied potential differences; the streaming potentials developed by pressures across biological membranes would be too small to detect, but in large pores such as xylem or phloem vessels or in cell walls small pressures would result in easily measured potentials.

Simultaneous measurements of minute electrical current and water flow through single living cells of Nitella translucens have shown that there is an electro-osmotic transport of the order of 100 moles of water per Faraday in the direction of the positive ion flow. This implies the existence of water-filled charged pores through the plasmalemma and tonoplast of the Nitella cell. The pores available for ion movement are far too few to account for the high water permeability of the cell membranes, and the possible extra turgor pressures which might be produced by an electro-osmotic flow through these pores could not be more than 10−4 atmosphere.

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There is evidence that current-induced volume flows which are normally considered to be electro-osmosis have two components: a true electro-osmotic component due to frictional interaction and local osmosis due to a transport number effect. Recent measurements of such components and other parameters for both cells and cell walls are used to reappraise the possibility that electro-osmosis in cells may be explained in terms of electro-osmotic coupling in cell walls alone.

The mobilities of Cu2+, Ni2+, Co2+, Zr2+, and Fe3+ have been calculated from their ionophoretic speeds on paper, after correcting for electro-osmotic and tortuosity effects. The corrected mobilities are of the same order as those in free solution.

A note on the Possibility of Transforming an Equation derived for Electro-osmosis with Surface Conductance correction into the corresponding Electrophoretic Equation.

Third Order Interaction Coefficients.

Phenomenological equations, based on the thermodynamics of irreversible processes have been developed for the electro‐osmosis as observed in paper electrochromatography when the electrodes are placed directly on or in the paper.

The short term effects of chloramphenicol, polymyxin sulfate and oligomycin A + B (the latter in 0,5M alcoholic solution) on the basic flow and the electrosmosis inNitella were studied. Both chloramphenicol and polymyxin increase the basic flow but only polymyxin increases the electro-osmotic efficiency.

Hydrogen-ion transport numbers, water transference numbers, and acid absorption are reported for some cation-exchange membranes in presence of 0.1N, 1.0N, and 5.0N sulphuric acid. The transport numbers of hydrogen ion remain fairly close to unity even at the highest acid concentration; this is largely due to the retardation of the anions by the electro-osmotic water flux. With increasing acid concentration the water transference number falls to a lower limit of 1.0 mole per faraday; with the driest membrane used this value is obtained at all acid concentrations used. This behaviour suggests that when there are less than about 11 moles of water available per hydrogen ion in the membrane, association occurs between sulphonate groups and hydrogen ions, with consequent immobilization of the latter.