Electrokinetics at high ionic strengths: Alumina

Electrophoresis was used to study ζ potentials of α-alumina in the presence of the following electrolytes: LiI, LiNO3, NaCl, NaBr, NaNO3, KCl, KNO3, CsCl, at concentrations up to 2 M. Unexpectedly high values of the ζ potentials (up to 20 mV) were found at pH 4 in 1 M solutions of these electrolytes. The results obtained at pH > 9 in the presence of 1 and 2 M solutions of lithium salts suggest a shift in the IEP to high pH, which is analogous to a shift observed by means of electroacoustic method.