Adhesion 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

• Published in: Journal of colloid and interface science 1994, Vol.165 (2), p.459-466
• Main Authors: Andrade, Estela Marı́a, Molina, Fernando Victor, Gordillo, Gabriel Jorge, Posadas, Dionisio
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-liquid interface; Surface physical chemistry
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.1994.1250

In this work the influence of several factors on the adherence of hematite particles onto mercury electrodes is studied through capacitance, C, measurements at different applied potentials, E. The C/E relationship shows two maxima at potentials more positive and more negative with respect to the zero charge potential of the bare metal. The pH dependence of the capacity maxima shows an inflection point at a pH of about 4. The capacitance increases with ionic strength. The C/E curve depends markedly on the nature of the anion present in the electrolyte. In the potential range between the maxima, the capacitance depends on the potential in an approximately parabolic way. The number of attached particles as a function of hematite concentration in solution shows an adsorption isotherm-like behavior. The experimental findings can be rationalized in terms of the influence of the different variables on the electrochemical free energy of adhesion.