Thermal decomposition kinetics of humic substances extracted from mid-Rio Negro (Amazon Basin) soil samples

• Autor(a) principal: Oliveira,Luciana Camargo de
• Data de Publicação: 2009
• Outros Autores: Ribeiro,Clovis Augusto, Rosa,André Henrique, Botero,Wander Gustavo, Rocha,Julio Cesar, Romão,Luciane Pimenta Cruz, Santos,Ademir dos
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000600020
• topic: soils; humic substances; kinetics; thermal analysis; Amazon

In this work humic substances (HS) extracted from non-flooded (Araçá) and flooded (Iara) soils were characterized through the calculation of stability and activation energies associated with the dehydration and thermal decomposition of HS using TGA and DTA, electronic paramagnetic resonance and C/H, C/N and C/O atomic ratios. For HS extracted from flooded soils, there was evidence for the influence of humidity on the organic matter humification process. Observations of thermal behaviour, with elemental analysis, indicated the presence of fossilized organic carbon within clay particles, which only decomposed above 800 ºC. This characteristic could explain the different thermal stability and pyrolysis activation energies for Iara HS compared to Araçá HS.