THERMAL-ANALYSIS OF MONTMORILLONITE-AMINOTRIAZOLE INTERACTIONS

In the present investigation, DTA and TG techniques were used to study the thermal behaviour of montmorillonite treated with solutions of th e pesticide aminotriazole (AMT), in nitrogen flow. These techniques ha ve 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 adsorbe d AMT, delaying its first decomposition step, and catalyses AMT final decomposition at lower temperatures. The DTA curve of montmorillonite- AMT mechanical mixture differs from the sum of those of the clay miner al and the pesticide heated individually. Montmorillonite dehydroxylat ion occurs at lower temperature, indicating a complex formation betwee n AMT and the mineral during the heating process. However the DTA of t he mixture is different from that of the complex previously studied, i ndicating that in the complex obtained by heating the physical mixture AMT is adsorbed as neutral molecule or as a product of its decomposit ion.