Ntalikwa, J. W.Bryant, R.Zunzu, J. S. M.2020-03-092020-03-092001Ntalikwa, J., Bryant, R. & Zunzu, J.(2001). Electrophoresis of colloidal α-alumina. Journal of Colloid Polymer Science 279, 843–849http://hdl.handle.net/20.500.12661/2137Abstract. Full Text is available at: https://link.springer.com/article/10.1007/s003960100502#citeasMeasurements of the electrophoretic mobility (u E) of particles of colloidal α-alumina were made as a function of pH, electrolyte concentration and electrolyte type (NaCl, NaNO3 and KCl) using two similar instrumental techniques. Significant differences (50% or less) in the values of u E of particles in NaCl were obtained from the two instruments; however, the isoelectric points (IEPs) (the pH at which u E=0), estimated from the two sets of measurements, occurred at 7.5 ± 0.3 and 7.8 ± 0.05 and were not significantly different. The latter estimate corresponds with those for particles in KCl and NaNO3 of 8.05 ± 0.11 and 7.95 ± 0.18, respectively, made using the same instrument and indicate that the IEP was a weak function of electrolyte type. When cations acted as counterions (pH > IEP), the absolute magnitudes and the ranges of u E with electrolyte concentration were found to be significantly less than when anions acted as counterions (IEP > pH). Estimates of the zeta potential (ζ), made using various procedures, showed variations of up to 25% at low ratios of electrical-double-layer thickness (κ −1) to particle radius (a) (κa∼10) and were of a similar scale to differences in u E, but no significant variations (95% confidence) in ζ were obtained at high values (κa∼200).enColloidAluminaElectrophoretic mobilityZeta potentialIsoelectric pointsIEPsArticle