摘要:

AbstractAn exact derivation of the conductance of parallel double‐layers as a one‐dimensional model of polyelectrolyte solutions is presented. The conductance tends to a finite limit, inversely proportional to the square of the (one‐dimensional) polyelectrolyte concentration, as the polyelectrolyte charge density increases indefinitely. In other words, the conductance tends to zero with the square of the inverse polyelectrolyte concentration in a way independent of the polyelectrolyte charge density. Approaching these limits, the ionic mobility of the counterions predominates over that of the fixed charges. The assumption of superposition of the external and internal electrostatic fields is shown to be inexact even at the limit of very small external f

ISSN:0021-2148    

DOI:10.1002/ijch.197300023

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe transport of polyions in solutions under an applied electric field is controlled by the three counterion effects: the electrophoresis effect, the field distortion effect and the counterion relaxation effect. Recent experimental and theoretical studies have mainly considered the electrophoresis effect which is a hydrodynamic effect of the medium charged by the counterions. In this paper, the other two effects, which result from the distortion of the counterion atmosphere around the polyion, are evaluated through the strict but simple analysis of the diffusion equations for low molecular ions and the Poisson equation. It was found in this study that these two effects are remarkably important for the system of coiled macroions fairly free‐drained. It was also demonstrated that the applied electric field is strongly depressed near the polyions by the shielding effect of counterions. This result is very different from the various theories which have assumed a constant applied field in the whole space. A cubic free‐volume model was adopted in this theory and the case for infinite dilution of polyion was also discussed as a special case of the free‐volume. The most important factor in our mobility expression is the apparent polyion charge expressed by the counterion activity. The results were compared with the experiments referring to the additivity rule for counterion act

ISSN:0021-2148    

DOI:10.1002/ijch.197300024

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractElectrical mobilities of counterions in aqueous solutions of potassium polyacrylate, potassium polymethacrylate and sodium polymethacrylate were investigated by moving boundary electrophoresis. At constant polymer concentration, the mobility of counterions decreases with an increase in the degree of neutralization. At a constant degree of neutralization, the mobility increases with an increase in the concentration of the polyelectrolyte. The mobilities of the polyion were derived from the counterion mobility and conductance. The fraction of bound ions increases with the degree of neutralization and reaches a value of about 60%. Osmotic coefficients were evaluated from the mobility data and compared with the values derived from osmotic measurements.

ISSN:0021-2148    

DOI:10.1002/ijch.197300025

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe complexation of sodium ions with the macrocyclic polyethers dibenzo‐18‐crown‐6 (DBC),cis‐4,4′‐dinitro‐dibenzo‐18‐crown‐6 (NDBC) andcis‐4,4′‐diamino‐dibenzo‐18‐crown‐6 (AmDBC) has been investigated conductometrically in the temperature range 10–40°C. A computer program based on iteration procedure has been used for the calculation of the equilibrium constants. In DMF, KNDBC

ISSN:0021-2148    

DOI:10.1002/ijch.197300026

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractUsing the nonequilibrium thermodynamic treatment of Kedem and Katchalsky a study has been made of series arrays of ion‐exchange membranes. A rule has been found which identifies certain classes of intermembrane concentrations which vary in the same way with respect to current under different steady‐state conditions. Among these is a set which is independent of the value of the steady‐state current. For the special case of series arrays containing alternately positive and negative fixed charges, with indefinitely large end reservoirs, it is shown that in the steady‐state the array may possess a set of desalinated intermembrane compartments, or a set of salinated intermembrane compartments, but never both simultaneously. This leads to the conclusion, which has been tested experimentally, that a large array of this kind may act as an efficient rectifier. The steady‐state concentration profile across a large array may be radically altered by changing a single membrane in the array, or even adding a single membrane at one end of the array. The approach to the steady‐state has been examined by means of a relaxation calculation, which leads to certain conclusions relating to optimization of flow‐rates in desalination by el

ISSN:0021-2148    

DOI:10.1002/ijch.197300027

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe effect of salt on the pH titration curves of weak acid or weak base ion exchangers is discussed, and conditions are formulated for the representation of such titration data by a single master curve. Inspection of experimental data both from the literature and from new measurements reported in this paper shows appreciable deviations from single master curves. These deviations are discussed in terms of the effect of salt on the activity of water. Thermodynamic considerations show that such deviations provide quantitative information on the number of water molecules taken up by the resin following the ionization of the weakly aeidic or basic groups involved. Relatively large changes in hydration are found in some systems; these are especially pronounced in systems undergoing conformational transitions.

ISSN:0021-2148    

DOI:10.1002/ijch.197300028

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractAluminum hydroxide‐coated montmorillonites have been shown to exhibit exchange properties which differ from those of pure montmorillonites. The direction of change was found to depend on the coating method used and the pH at which the coating is applied. The aluminum hydroxide‐coated montmorillonites were prepared by two different methods at two pH's: (1) reacting aluminum chloride and sodium hydroxide in the presence of the clays (pH 7), and (2) titrating aluminum‐saturated clays with calcium hydroxide to an alkaline pH (∼10). The resulting clay systems were equilibrated with calcium‐magnesium solutions. The first system showed preferential adsorption of calcium over magnesium because the clays contained exchangeable sodium due to the precipitation of aluminum hydroxide in the presence of the clay. The second system showed no preference either for calcium or for magnesium. A distribution coefficient of unity resulted from compensation of exchangeable calcium by magnesium released from the aluminum

ISSN:0021-2148    

DOI:10.1002/ijch.197300029

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThis paper presents a method for the study of the transport of ions (K+, Na+, Cs+, Cl−, Br−) across adsorbed monolayers at the respective amalgam/water and mercurous halide/water interfaces. The method involves cathodic formation and anodic stripping (inverse polarography) of amalgams and in the reversed order (anodic formation) of mercury halides. Galvanostatic measurements were performed using a stationary mercury drop electrode, a platinum counter electrode and a Ag/AgCl reference electrode. Phase sensitive ac polarography was employed to determine the differential capacity of the electrical double layer in the presence of adsorbed monolayers. Adsorbed monolayers of octadecyltrimethylammonium and of eicosanyltrimethylammonium ions have different permeabilities towards the various cations; cesium ions are the most permeable. The transport of Cl−and Br−was studied across adsorbed monolayers of long chain quaternary ammonia and carboxylic acids and of polyglutamic acid at the mercurous halide/water interface. The anionic permeability depends on the type of anion, the composition of the monolayer, and the charge density of the monolayer and the interface. Ion transport is correlated with the packing in the monolayer. During the anodic stripping of potassium and sodium amalgams in the presence of octadecyltrimethylammonium chloride, and potassium, sodium and cesium amalgams in the presence of eicosanyltrimethylammonium chloride, sustained oscillations of the electrode potential were observed. The frequency varies from about 0.3 to 1.0 Hz, and depends on the current density, the duration of the anodic stripping, the composition of the monolayer, and the temperature. The amplitude of the oscillations varies from 100 to 500 mV. These oscillations involve the following processes: potential build‐up across the monolayer, monolayer rupture (hole formation), followed by hole closure. The oscillations were detected also by instabilities in the measurements of the differential

ISSN:0021-2148    

DOI:10.1002/ijch.197300030

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractA procedure for the measurement of ionic transport numbers, with the aid of current‐carrying electrodes that are introduced into a hyperfiltration cell is suggested. This procedure is suitable for adsorbed polymer layers and dynamic membranes. For membranes adequately described by the fixed charge model, allowing for ion‐association, a simple relation between transport numbers and salt rejection is derived. This leads to a test for the mechanism of salt reject

ISSN:0021-2148    

DOI:10.1002/ijch.197300031

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractA kinetic analysis of facilitated diffusion across cell membranes on the basis of four models is presented. These models are all general in that in no case is symmetry assumed, nor is any particular reaction step considered as rate‐limiting. In one model there is only one form of the free carrier and one form of the bound carrier. In the second model there are two forms of both bound and of free carrier. In the third and fourth models there are two forms of one of these, but only one form of the other. These models fall into two classes: that with one form of the free carrier and that with two forms. Within each class the models give identical predictions for steady‐state fluxes of substrates. It is shown how to distinguish between these two classes using experimental data, and criteria are provided enabling one or other class, or both classes, of model to be rejected. A complete kinetic analysis of a system of either class may be achieved on the basis of a small number of parameters, derived from flux measurements. The significance of these parameters on a molecular level are discus

ISSN:0021-2148    

DOI:10.1002/ijch.197300032

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY