Emanation thermal analysis of TIXOTON (activated bentonite) treated with organic compounds

TIXOTON (Ca-bentonite activated by sodium carbonate) was treated with four different organic compounds representing organic acids, bases, non-ionic polar molecules and non-polar molecules found in waste and sewage water. They were acetic acid, diethylamine, ethyleneglycol and n-heptane. The first three were used as 5% aqueous solutions, and the latter as a neat liquid. Cation exchange reactions, which occurred between the montmorillonite fraction of TIXOTON and acetic acid or diethylamine solutions, resulted in H–Al-montmorillonite or diethylammonium-montmorillonite, respectively. Ethyleneglycol displaced water in the interlayer space of montmorillonite, and n-heptane was adsorbed on other components of the TIXOTON. The products were characterized by emanation thermal analysis (ETA) supplemented by TG and XRD. A revealed “in situ” microstructure changes of montmorillonite, iron hydrous-oxide and amorphous silica, occurring during the heating of TIXOTON treated with the organic compounds. These changes accompany thermal dehydration, dehydroxylation and formation of meta-montmorillonite, and its subsequent annealing and recrystallization. The organic compounds have an influence on the interlayer water structure and the temperature at which the annealing of the meta-phase begins.