INTRINSIC PROTON AFFINITY OF REACTIVE SURFACE GROUPS OF METAL (HYDR)OXIDES - APPLICATION TO IRON (HYDR)OXIDES

An improved method has been developed for the calculation of proton af finities of individual surface groups of metal (hydr)oxides, The metho d is a refinement of the multi site complexation (MUSIC) model, In the MUSIC model, Pauling bond valences are used to predict the individual proton affinities of surface groups of metal (hydr)oxides, One of the major changes in the refined MUSIC model is that the Pauling bond val ences are redefined with a method in which the bond valence is related to the bond length. In this paper, the refined MUSIC model is applied to three different iron (hydr)oxides (goethite, lepidocrocite, and he matite). The resulting proton affinities can be combined with the crys tal structure and morphology in order to describe the experimental cha rging curves. The charging curves could be described very well for min erals with a well-known (goethite) or reasonably well-known (lepidocro cite) crystal morphology, For crystals of which the morphology is less well known (hematite), the refined MUSIC model can be a powerful supp ort for a suggested morphology, (C) 1998 Academic Press.