RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

The aim of this research was to provide a mechanistic interpretation for fluoride adsorption onto kaolinite over a range of experimental conditions that are important environmentally. Proton titration data of kaolinite showed that the pH_zpc=8.9, and the intrinsic acidity constants (of dominant ≡AlOH) sites were pK_a1=−9.23, and pK_a2=7.57. The mineral surface exhibited some site heterogeneity. The diffused layer model using the following reaction stoichiometries was employed to quantify anion adsorption data:

≡AlOH + H⁺ + F⁻ → ≡AlF + H₂O   logK_{equiv;AlO/ndash;F} = 15.16
≡SiOH + H⁺ + F⁻ → ≡SiF + H₂O   logK_{equiv;SiO/ndash;F} = 13.10