Mr. Provenzano et N. Senesi, Thermal properties of standard and reference humic substances by differential scanning calorimetry, J THERM ANA, 57(2), 1999, pp. 517-526
Differential Scanning Calorimetry combined with Fourier transform infrared
spectroscopy, was applied to the study of a number of fulvic and humic acid
s extracted from soils, peat, river and seawater. The thermal patterns obta
ined were related to the nature and origin of samples. The low-temperature
endotherms were attributed to dehydration and loss of peripheral polysaccha
ride chains. The endotherm at 250 degrees C observed for soil FA was ascrib
ed to partial decarboxylation of more labile surface COOH groups, whereas t
he high-temperature exotherms at about 500 degrees C were related to the de
gree of polycondensation of the aromatic network of the humic molecules.