Adherence of Colloidal Hematite onto Metallic Surfaces. II Influence of Electrode Potential, pH, Ionic Strength, Colloid Concentration, and Nature of the Electrolyte on the Adhesion on Mercury

E. M. ANDRADE; F. V. MOLINA; GJ GORDILLO; D POSADAS,

JOURNAL OF COLLOID AND INTERFACE SCIENCE

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: San Diego, CA; Año: 1994 vol. 165 p. 459 - 466

0021-9797

In this work the influence of several factors on the adherenceof hematite particles onto mercury electrodes is studied throughcapacitance, C, measurements at different applied potentials, E.The C-E relationship shows two maxima at potentials morepositive and more negative with respect to the zero charge po-tential of the bare metal. The pH dependence of the capacitymaxima shows an inflection point at a pH of about 4. The ca-pacitance increases with ionic strength. The C-E curve dependsmarkedly on the nature of the anion present in the electrolyte.In the potential range between the maxima, the capacitance de-pends on the potential in an approximately parabolic way. Thenumber of attached particles as a function of hematite concen-tration in solution shows an adsorption isotherm-like behavior.The experimental findings can be rationalized in terms of theinfluence of the different variables on the electrochemical freeenergy of adhesion.