INFRARED STUDY OF THE EFFECTS OF THERMAL-TREATMENT ON MONTMORILLONITE-BENZIDINE COMPLEXES .2. LI-MONTMORILLONITE, NA-MONTMORILLONITE K-MONTMORILLONITE, RB-MONTMORILLONITE AND CS-MONTMORILLONITE

Li-, Na-, K-, Rb- and Cs-montmorillonites were saturated with benzidin e, these organo-clay complexes heated under vacuum to 200-degrees-C an d IR spectra recorded at various temperatures. Benzidine is mostly bou nd to interlayer cations through water molecules, except in Cs-clay wh ere bonding to hydrophobic water and to water molecules which are hydr ogen bonded to the oxygen plane predominates. During the thermal treat ment water is lost and alkali cations coordinate directly with benzidi ne. In Cs-, and to some extent also in Rb- and K-montmorillonite, benz idine is oxidized to semiquinone and quinoidal cation during the therm al treatment.