ADSORPTION OF 2,2'-BIPYRIDYL ONTO SEPIOLITE, ATTAPULGITE AND SMECTITE GROUP CLAY-MINERALS FROM ANATOLIA - THE FT-IR AND FT-RAMAN SPECTRA OF SURFACE AND INTERCALATED SPECIES

The adsorption of 2,2'-bipyridyl by natural sepiolite, attapulgite, hectorite, saponite and natural and ion exchanged (Mn, Fe, Co, Ni, Cu, Zn or Sn) bentonites has been investigated by FT-IR and FT-Raman spectroscopy. Spectroscopic results indicate that most of the adsorbed molecules are coordinated to either exchangeable cations (in the case of smectite group clays) or Lewis acidic centres fin the case of sepiolite and attapulgite) as bidentate ligands. The formation of monoanionic surface species has also been detected, to a relatively small extent. No physisorbed surface species has been observed. XRD patterns and UV-visible spectra of the samples are also recorded for additional information.