Adsorption of H+, OH− and Background Electrolyte Ions on Alumina — Point of Zero Charge, Triple Layer Model (TLM) Parameters and Thermodynamic Parameters

Abstract

The surface charge σ0 on aqueous suspensions of alumina was measured as a function of pH in various NaNO3 concentrations and at different temperatures. The values of the point of zero charge (p.z.c.), pK1(int), pK2(int), pKNa+(int) and pKNO3–(int) for alumina suspended in NaNO3 solutions were obtained in the temperature range 17–45°C from potentiometrie titration data. The values of ΔS0 and ΔH0 of the dissociation equilibria and complexation equilibria were calculated from these equilibrium constants. Standard Gibbs energies, enthalpies and entropies for proton adsorption on alumina were also obtained. The surface charge σ0 on aqueous suspensions of alumina was measured as a function of pH and concentration of Ca(NO3)2 or Na2SO4 solution.