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 pHzpc=8.9, and the intrinsic acidity constants (of dominant ≡AlOH) sites were pKa1=−9.23, and pKa2=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 logKequiv;AlO/ndash;F = 15.16
≡SiOH + H+ + F− → ≡SiF + H2O logKequiv;SiO/ndash;F = 13.10
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