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Abstract  

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.

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Abstract  

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.

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Abstract  

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 treatment.

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is greatly enhanced. Thermal analysis of organo-clay complexes Several thermal analysis methods are used in the study of thermal properties and processes of – complexes and of their fine structure. Among these techniques

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Thermal analyis of hexadecyltrimethylammonium–montmorillonites

Part 1. Thermogravimetry, carbon and hydrogen analysis and thermo-IR spectroscopy analysis

Journal of Thermal Analysis and Calorimetry
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-clay complex by multiple

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. Soil Sci Soc Am J 52 : 652 – 660 10.2136/sssaj1988.03615995005200030010x . 3. Yariv , S 2002 Introduction to organo-clay complexes and interactions

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S . Differential thermal analysis (DTA) in the study of thermal reactions of organo-clay complexes . Natural and Laboratory-Simulated Thermal Geochemical Processes ; 2003 . p. 253 – 296 . 30

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Thermal analysis of hexadecyltrimethylammonium-montmorillonites

Part 2. Thermo-XRD-spectroscopy-analysis

Journal of Thermal Analysis and Calorimetry
Authors: Isaak Lapides, Mikhail Borisover, and Shmuel Yariv

hydrophobicity of organoclays Yariv , S , Cross , H , eds. Organo-clay complexes and interactions . New York : Marcel Dekker ; 2002 175 – 191 . 4. Murray HH . Clays

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