The study of kaolinite surfaces is of industrial importance. In this work we
report the application of chemometrics to the study of modified kaolinite surfaces.
DRIFT spectra of mechanochemically activated kaolinites (Kiralhegy, Zettlitz, Szegi
and Birdwood) were analysed using, Principal Component Analysis (PCA), and
multi-criteria decision making (MCDM) methods, PROMETHEE and GAIA. The
clear discrimination of the Kiralhegy spectral objects on the two PC scores plots (400-
800 and 800-2030 cm-1) indicated the dominance of quartz. Importantly, no ordering
of any spectral objects appeared to be related to grinding time in the PC plots of these
spectral regions. Thus, neither the kaolinite nor the quartz, are systematically
responsive to grinding time according to the spectral criteria investigated. The third
spectral region (2600-3800 cm-1 – OH vibrations), showed apparent systematic
ordering of the Kiralhegy and, to a lesser extent, Zettlitz spectral objects with grinding
time. This was attributed to the effect of the natural quartz on the delamination of
kaolinite and the accompanying phenomena (i.e. formation of kaolinite spheres and
water). With the MCDM methods, it was shown that useful information on the basis
of chemical composition, physical properties and grinding time can be obtained. For
example, the effects of the minor chemical components (e.g. MgO, K2O etc) indicated
that the Birdwood kaolinite is arguably the most pure one analysed. In another
MCDM experiment, some support was obtained for the apparent trend with grinding
time noted in the PC plot of the OH spectral region.