Adsorption electrolytes

Electrolyte adsorption on metals is important in electrochemistry [167,168]. One study reports the adsorption of various anions an Ag, Au, Rh, and Ni electrodes using ellipsometry. Adsorbed film thicknesses now also depend on applied potential. 

Sadiq, M. Lindsay W.L. (1988) The solubility product of soil maghemite. Soil Sci. 146 1-5 Sahai, N. Sverjensky D.A. (1997) Solution and electrostatic model for specific electrolyte adsorption. Geochim. Cosmochim. Acta 61 2827-2848... 

Van Riemsdijk.W.A. Bolt, G.H. Koopal, L.K. Blakemeer, J. (1986) Electrolyte adsorption on heterogeneous surfaces. Adsorption models. 

Third, the material of this chapter is a mix of descriptive and theoretical concepts. The most important descriptive observation is the existence of two-dimensional phases. The theoretical content of the chapter is mostly thermodynamic in origin. Three major results are the equations named after Gibbs, Langmuir, and Lippmann. We are mostly concerned with uncharged surfaces, except for a brief discussion of electrolyte adsorption at a polarizable mercury electrode in Section 7.11. 

While surface charge is by no means the only factor responsible for electrolyte adsorption (94), particularly organic electrolytes (9, 27), the extent of adsorption of the less specifically adsorbed species, such as the simple aquo ions and, for example, primary amines and alkyl sulfonates, decreases rapidly when the sign of the oxides surface charge is changed to that of the sorbing species (6, 10). 

Specific electrolyte adsorption can occur on oxides by ion exchange with structural cations, with hydrogen or hydroxyl of the surface hydroxide groups, or with impurities (92, 94). Ions which can form insoluble compounds or undissociated complexes with a component of the solid crystal lattice adsorb more strongly than those which cannot (2). This does not imply or require that such complexes or compounds do or do not form. The question may be left open. It does imply that, of a series of species which form insoluble compounds with components of the solid, that which forms the least-soluble compound will be adsorbed most strongly. Thus any generalization which can be used to predict solubility or complexing tendency can be extended to predict adsorba-bility, at least qualitatively. 

Stripping analysis is a two-step technique. The first or deposition step commonly involves the electrolytic deposition of a small portion of the metal ions in solution into the mercury electrode to preconcentrate the metals. Non-electrolytic (adsorptive) accumulation schemes have also been developed for expanding the scope of stripping analysis to trace metals that cannot be electrodeposited. The preconcentration step is followed by the stripping (measurement) step, which involves the dissolution (stripping) of the deposit. Different versions of stripping analysis can be employed, depending upon the nature of the deposition and measurement steps. 

The technique has been extended to other electrochemical phenomena such as electro-deposition and dissolution of metal films, hydrogen absorption in metals, under-potential deposition, electrolyte adsorption, and ion and solvent exchange in redox polymer layers and electrochemically driven self-assembly, etc. [5]. 

Thermal effects of electrolyte adsorption on potato starch have also been observed.476 For the alkali-metal salts, adsorption and accompanying... 

The potentials of the capacity minima are strongly dependent on the pH of the electrolyte. The current potential curves show the same dependence. These potential differences are not caused by changes in the space charge. It must be assumed that the source of these potential differences lies between the semiconductor surface and the Helmholtz plane in the electrolyte. Adsorption of OH ions may be an explanation of this effect. 

IR/Raman Binding prop Yes Huge bulk electrolyte adsorption... 

Kosmulski, M., Oxide/electrolyte interface Interpretation of supporting electrolyte adsorption data, Pol. J. Chem., 67, 1831, 1993. 

Table I. Reactions and Selected Intrinsic Equilibrium Constants for Surface Ionization and Electrolyte Adsorption...

Figure . Na and CP on Corundum Comparison of experimental (18) and simulated zeta-potential data. Modeling parameters for surface ionization and electrolyte adsorption are given in Table I. Surface site concentration Z SOH = 2.34 x 10 M.

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