Multivalent ion screening of charged glass surface studied by streaming potential measurements

Abstract

We used streaming potential technique to measure ζ potentials for glass as a function of Co(NH3)6Cl3 concentration, KCl concentration, and pH. Charge inversion was observed only at high surface charge densities and was inhibited by increased KCl concentration. Measured ζ potentials were compared with predictions from a recent theory by dos Santos et al. [J. Chem. Phys. 132, 104105 (2010)] that models multivalent ions adsorbed to the charged surface as a strong coupled liquid (SCL). The location of shear plane was determined independent of the SCL theory, allowing a rigorous experimental test of the theory with no fitting parameters. We found that SCL predictions agree quantitatively with our experimental data.