Acidity and Alkali Metal Adsorption on the SiO 2–Aqueous Solution Interface

Abstract

The intrinsic deprotonation constant (p K int a 2 ) and the intrinsic ion exchange constants (p K int Me + ) of Li +, Na +, and K + on SiO 2 were uniquely determined at 30°C by using the potentiometric titration data, the Gouy–Chapman–Stern–Grahame (GSCG) model for the structure of the electrical double-layer (edl) and the double-extrapolation method. The values of these constants were p K int a 2 =6.57, p K int Li + =p K int Na + =p K int K + =5.61. The chemical meaning of intrinsic equilibrium constants and the equality in the values of p K int Li + , p K int Na + and p K int K + were discussed.