Effect of gamma-irradiation on clays and organoclays: a Mossbauer and XRD study

The interaction of gamma-rays with smectite clays induces noticeable change s in the structure and physicochemical properties of the minerals. For sodi um-montmorillonite. Mossbauer spectra show that gamma-irradiation causes a partial reduction of trivalent iron to the divalent state due to hydrogen r adicals production from the radiolysis of interlayer water. The XRD results show no change in the interlayer space upon irradiation and therefore the radiolysis of inter-layer water causes no measurable changes in the archite ctural organization of the interlayer environment. Intercalation of simple organic molecules (ethylene glycol, tert-butanol and tetraalkylammonium sal ts) causes partial oxidation of structural divalent iron and affects the Mo ssbauer parameters of the M-1 and M-2 ferric components Irradiation of ethy lene glycol- or tert-butanol-clay composites indicates reduction of trivale nt iron to the divalent state. XRD data show that the irradiation of clay-e thylene glycol complex causes collapse of the initial double layer of glyco l molecules to a single layer complex. Finally, XRD results show that the e ffects of gamma-irradiation on clay-tetraalkylammonium complexes depend upo n the chain length of the organic cations.