CHARACTERIZATION OF ACIDITY OF PILLARED CLAYS BY PROTON AFFINITY DISTRIBUTION AND DRIFT SPECTROSCOPY

Diffuse reflectance FTIR (DRIFT) spectra and potentiometric titration data have been obtained for montmorillonite samples pillared with diff erent polycations. The IR spectra are interpreted after deconvolution into Voigt band profiles. The titration data are analysed using a stab le numerical method for the solution of the adsorption integral equati on (SAIEUS). The pK distributions obtained are used to characterize th e acidic properties of the modified minerals to demonstrate the relati onship between these properties and the coordination of cations in the pillaring species. Heat treatment enhances the acidity of the materia ls which may be the result of the rearrangement of pillars (dehydroxyl ation). The approach presented enables one to assess both qualitativel y and quantitatively the number and strength of acidic sites present o n the surface of pillared clays.