Stefan Minc

The adsorption of NCS-ion on mercury from aqueous solutions

Summary The electrocapillary curves of mercury were obtained in concentrated aqueous KNCS solutions at two temperatures. The procedure indicated by Parsons was applied to determine the amount of adsorbed ions. Experimental data were fitted to the Frumkin isotherm which contains a constant accounting for the long-range interaction between adjacent adsorbed ions. This isotherm describes satisfactorily the adsorption of NCS- anion. It was observed that the temperature change has only a slight effect upon parameters such as: q - 1 , Δ G 0 and the Esin and Markow coefficient, which describe quantitatively the adsorption of NCS- ion. Grahame s theory of the inner layer was applied to determine its thickness and the most probable arrangement of ions specifically adsorbed on the mercury surface.

The temperature effect on thermodynamic parameters in the adsorption of chloride ions at the mercury/aqueous HC1 solution

Summary The adsorption of Cl− ions on mercury from aqueous HCl solutions was studied as a function of concentration (0.1–1.4 M) and temperature (25, 40 and 60°C) using measurements of differential capacity and of interfacial tension. It was found from the temperature variation of the Esin-Markov coefficient and of the adsorbed charge, q′Cl−, that the adsorption of Cl− ions on mercury decreases with increasing temperature. Some parameters characterizing the structure of adsorbed ionic layers at various temperatures were determined on the basis of Parsonss thermodynamic analysis. The effect of temperature on the components of the inner layer capacity and on the (x2−x1)/x1 thickness ratio were discussed. In addition, some data concerning the entropy of adsorption of Cl− ions on mercury were presented.

Structure of the mercury/water + methanol mixtures interface in a thiourea-containing system

Abstract The adsorption of thiourea at mercury from water+methanol mixtures containing 0.1 M KF and various mole fractions of methanol, was studied on the basis of previously published differential capacity results and the potential shift produced by concentration changes of thiourea. The data were analysed to obtain the surface pressure and the surface excess of thiourea respectively, as a function of charge and bulk thiourea concentration. Then, using the methods previously developed by Parsons, Frumkin isotherm constants and electrostatic properties of the inner layer were determined. The parameters are compared with those published by Parsons et al. for the adsorption of thiourea from pure water and methanolic solutions.

Investigation of polar-oil/water electro-chemical interphase properties—II: Solvation energies of 1:1 electrolytes in water saturated nitrobenzene

Abstract From data on the distribution potential differences determined by the dynamic condenser method, the limiting distribution coefficients of 1:1 electrolytes in the nitrobenzene/water system and the limiting solvation energies of these salts in water saturated nitrobenzene are calculated. The possibility of using the data to estimate the ion solvation energies, the limiting distribution coefficients of ions, and the absolute values of the distribution potentials is discussed.

Adsorption of thiourea on mercury in water + methanol mixtures

Abstract The adsorption of thiourea on mercury has been investigated by capacitance measurements in three water + methanol mixtures, having various mole fractions of methanol. The back integration method was employed to obtain the curves of surface charge densities at the mercury surface for different concentrations of thiourea in the solution. As a test of specific adsorption in the systems studied the Esin-Markov plots were used.

Investigation of polar-oil/water electrochemical interphase properties—I. Application of the dynamic condenser method for nitrobenzene/water distribution potential difference measurements

Abstract The distribution potential differences ΔψMX of a series of 1 : 1 electrolytes in the nitrobenzene/water system have been determined by the dynamic condenser method. The use of this method in investigations of polar-oil/water cells makes it possible to replace the liquid junction from the oil-phase side by capacity coupling (dynamic condenser).

The influence of Triton X-100 ionophorous detergent on the transport kinetics of the tetramethylammonium cation through the human erythrocyte membrane

Abstract Triton X-100 facilitates the transport of tetramethylammonium cations (TMA + ) through the human erythrocyte membrane in vitro . These changes manifest themselves as the disappearance of the characteristic minimum of the function erythrocyte electrophoretic mobility plotted versus time, normally observed in the presence of TMA + ions. The incorporation of Triton X-100 molecules into the erythrocyte membrane induces both an increase in lipid phase fluidity and a decrease in cell glycoprotein coat viscosity. However, the resultant enhancement of the rate of penetration of TMA + ions across the lipid phase seems to be greater than the enhancement of their migration rate across the glycoprotein coat. Triton X-100 also induces changes in the membrane potential, which depend on the ionic content of the extracellular medium. These changes are probably too small to affect TMA + ion transport across the membrane significantly.

Contact Potential Difference of Cells in vitro

SummaryThe contact potential difference at the cell membranein vitro-air interface was measured using the dynamic oondensator method. The potential differences were found to be different for various types of living and dead cells.

Influence of temperature and concentration on adsorption potentials of KF, KCl and KBr at the mercury/dilute-aqueous-solution interface☆

Abstract From characteristic differential capacitance minima, for various concentrations and temperatures, adsorption potentials, τ, have been calculated. The change of adsorption potential with the mean ion activity, ln a ± , of the solution, and that of ∂ τ /∂ ln a ± with temperature, are discussed.

Determination of the electrocapillary maximum potentials by the vibrating interphase method

Abstract A method of vibrating interphase of the mercury-electrolyte solution was applied to the determination of electrocapillary maximum potentials. The results obtained are concordant with data indicated in the literature. The applicability of the method extends over a wide concentration range both in aqueous and non-aqueous solvents.