Zeta Potential in Different Electrolyte Solutions
A common analysis of the solid-water interface by means of the surface zeta potential applies an aqueous solution of a 1:1 electrolyte at an ionic strength in the range of 0.001-0.01 mol/L. However, material applications often require the zeta potential analysis in real-life solutions with a more complex composition. In such cases the specific interaction of solutes such as divalent ions or pH determining components with the solid surface have to be considered.
For solid surface characterization the zeta potential is commonly determined in the presence of a dilute aqueous solution of a 1:1 electrolyte such as NaCl or KCl. Monovalent anions and cations like chloride (Cl- ), sodium (Na+ ) or potassium (K+ ) are not expected to specifically interact with the solid surface, neither by physical adsorption nor by chemical binding. For divalent ions (e.g. Ca2+, Mg2+) or even more complex ions (e.g. chelating anions of organic acids) a contribution to the zeta potential is assumed. The investigation of ion adsorption on solid surfaces is subject to a specific application of the streaming potential and streaming current measurements.
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