engleski

Effect of Electrolytes on the Electroneutrality at the Interface

Recently, the measurements of the electrostatic potential at the inner plane of the electrical interfacial layer (surface potential phi0) were introduced by using metal oxide electrodes. The evaluation of the surface potential from the electrode potential requires the knowledge of the point at which the surface potential is zero, i.e. the point of zero potential (p.z.p., pHpzp). The numerical analysis based on the 2- pK mechanism of the Surface Complexation Model showed that pHpzp approximately coincides with pHiep if the ionic strength is kept enough low. At higher ionic strengths the values of pHiep and pHpzc might be different and pHpzp lies between these two point and is still close to the original value at low ionic strength, i.e. the point of electroneutrality pHeln. The experimental results of electrode potential dependence on pH measured with hematite electrode showed appreciable reproducibility in the acidic region. The slope of the phi0(pH) function is found to be significantly lower in magnitude than the Nernstian which is more pronounced at higher ionic strengths.

surface electroneutrality ; surface potential ; isoelectric point ; point of zero charge ; point of zero potential ; hematite

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