The hyphenated thermal analysis-mass spectrometry
technique (TA-MS) was applied for the investigation of the thermal behavior
of reference and aged parchment samples. The kinetic parameters of the process
were calculated independently from all recorded TA and MS signals. The kinetic
analysis showed the distinct dependence of the activation energy on the reaction
progress. Such behavior is characteristic for the multistage mechanism of
The comparison of the kinetic parameters calculated
from the different signals i.e. TG, DSC, MS for H2O,
NO and CO2, however, indicated that they were differently
dependent on the aging of the sample. For the parchment samples, the aging
almost does not change the kinetics of the decomposition calculated from the
DSC data: the influence of aging seems to be too negligible to be detected
by these techniques. On the other hand, the much more sensitive mass spectrometric
technique applied to the kinetic analysis allowed monitoring of visible changes
in the thermal behavior of the parchment samples due to the aging process.
The influence of aging was especially visible when the MS signals of water
and nitric oxide were applied for the determination of the kinetic parameters.
The applied method of the kinetic analysis allowed also the prediction
of the thermal behaviour of reference and aged parchment samples under isothermal
and modulated temperature conditions. Presented results have confirmed the
usefulness of thermoanalytical methods for investigating behaviour of such
complicated systems as leather or parchment.
Authors:K. Rajagopalan, P. Ravindran, and T. Radhakrishnan
TG-DTA-EGA studies have shown that anhydrous uranyl nitrate cannot be obtained by thermal decomposition of uranyl nitrate
hexahydrate. Hydrolysis and polymerization of the salt during dehydration resulted in hydroxynitrates which decomposed in
multiple steps with the evolution of oxides of nitrogen and water. The extent of hydrolysis dependend on the sample size,
heating rate and nature of sample containment. Large samples on decomposition at relatively high heating rates showed evolution
of nitric oxide even above 500°C. Infrared studies on the residues prepared at various temperatures supported the conclusions.
Authors:Szandra Baklanov, Ágota Horel, Györgyi Gelybó, Eszter Tóth, Márton Dencső, Emese Ujj, and Imre Potyó
, J.W. , Beauchamp , E.G. & Zhang , X.
1993 . Nitrous and nitricoxide emissions during nitrification and denitrification from manure-amended soil in the laboratory . Canadian Journal of Soil Science . 73 . 539