Controlled rate thermal analysis of nontronite

The thermal decomposition of a series of nontronites and a ferruginous smectite has been studied using a combination of high-resolution thermogravimetric analysis with a controlled heating rate and the mass spectrometry of evolved water vapour. The temperature-mass spectrum curve follows the differential thermogravimetric curve with precision, thus providing a second means of calculating the percentage weight loss. Three dehydration steps were observed in the CRTA experiment at around 86, 117 and 245 degrees Celsius depending on the nontronite sample. Two overlapping dehydroxylation steps were observed at approximately 350 and 400 degrees Celsius with a weight loss ratio of 1:2. A comparison is made between the between the results obtained from the dynamic differential thermogravimetric experiment and the controlled rate thermal analysis experiment