Electrical interfacial layer at hematite/dicarboxylic acid aqueous interface

Abstract

The interfacial properties of the system hematite/dicarboxylic acid were investigated in the presence of sodium perchlorate by means of adsorption, zeta potential and surface potential measurements. Maleic and fumaric acid were used as dicarboxylic acids. No significant difference in the surface potential values of hematite with and without the presence of dicarboxylic acids was observed. On the other hand, the zeta potential and the corresponding isoelectric point values obtained after adsorption of fumaric and maleic acids on hematite differ significantly from the zeta potential values of pure hematite. The parameters characterizing the electrical interfacial layer were determined on the basis of simultaneous interpretation of experimental data showing that there are some differences in adsorption behavior of two investigated dicarboxylic acids. The obtained equilibrium constant for adsorption of fumaric acid (log K° = 4.9 ± 0.2) is higher than the same constant obtained for adsorption of maleic acid (log K° = 4.0 ± 0.1) and the value of C1 was in both cases determined as 2.2 ± 0.3 F m-2.