Authors:E. Morillo, J. Pérez-Rodríguez, C. Real, and P. Sánchez-Soto
In the present investigation, DTA and TG techniques were used to study the thermal behaviour of montmorillonite treated with
solutions of the pesticide aminotriazole (AMT), in nitrogen flow. These techniques have been complemented by mass spectrometry of the evolved gases (EGA-MS).
AMT is adsorbed in the interlamellar space of montmorillonite as a cation. Results obtained in this study show that this provokes
a shift of the dehydroxylation peak of montmorillonite to lower temperatures than those of the untreated clay. Montmorillonite
protects the adsorbedAMT, delaying its first decomposition step, and catalysesAMT final decomposition at lower temperatures.
The DTA curve of montmorillonite-AMT mechanical mixture differs from the sum of those of the clay mineral and the pesticide heated individually. Montmorillonite
dehydroxylation occurs at lower temperature, indicating a complex formation betweenAMT and the mineral during the heating process. However the DTA of the mixture is different from that of the complex previously
studied, indicating that in the complex obtained by heating the physical mixtureAMT is adsorbed as neutral molecule or as a product of its decomposition.
Authors:A. Nasser, M. Gal, Z. Gerstl, U. Mingelgrin, and S. Yariv
The adsorption of the tertiary aromatic amide alachlor by Na-montmorillonite and Al-polyhydroxy-montmorillonite was investigated
by DTA, XRD, SEM and Thermo-FTIR Spectroscopy. This molecule is adsorbed into the interlayer space of the montmorillonite,
replacing interlayer water. In this organo-clay complex the interlayer water forms hydrogen bonds with N or O atoms of the
tertiary amide group. Samples which were aged during six months degraded by hydrolysis to give mainly secondary amide. This
reaction was catalysed by Al-polyhydroxy-montmorillonite more than by Na-montmorillonite.
Li-, Na-, K-, Rb- and Cs-montmorillonites were saturated with benzidine, these organo-clay complexes heated under vacuum to
200°C and IR spectra recorded at various temperatures. Benzidine is mostly bound to interlayer cations through water molecules,
except in Cs-clay where bonding to hydrophobic water and to water molecules which are hydrogen bonded to the oxygen plane
predominates. During the thermal treatment water is lost and alkali, cations coordinate directly with benzidine. In Cs-, and
to some extent also in Rb- and K-montmorillonite, benzidine is oxidized to semiquinone and quinoidal cation during the thermal
Authors:Shmuel Yariv, Mikhail Borisover, and Isaak Lapides
is greatly enhanced.
Thermal analysis of organo-claycomplexes
Several thermal analysis methods are used in the study of thermal properties and processes of – complexes and of their fine structure. Among these techniques
Authors:Isaak Lapides, Mikhail Borisover, and Shmuel Yariv
.0–1.5 mL min −1 ) to homogenized aqueous suspension of Wyoming bentonite (1.5%) during 5–6 h; (2) 15 h stirring; (3) centrifugation and determination of dissolved C in the supernatant; (4) sodium bromide was removed from the organo-claycomplex by multiple