caa a22 4500 463191110 CHVBK 20180406164909.0 cr unu---uuuuu 170326e20070901xx s 000 0 eng 10.1007/s10973-007-8437-5 doi (NATIONALLICENCE)springer-10.1007/s10973-007-8437-5 The kinetics of thermo-oxidative humic acids degradation studied by isoconversional methods [Elektronische Daten] [D. Válková, J. Kislinger, M. Pekař, J. Kučerík] Humic acids represent a complicated mixture of miscellaneous molecules formed as a product of mostly microbial degradation of dead plant tissues and animal bodies. In this work, lignite humic acids were enriched by model compounds and the model-free method suggested by Šimon was used to evaluate their stability over the whole range of conversions during the first thermooxidative degradation step. The kinetic parameters obtained were used to predict the stability at 20 and 180°C, respectively, which served for the recognition of processes induced by heat and those naturally occurring at lower temperatures. Comparison of the conversion times brought a partial insight into the kinetics and consequently into the role of individual compounds in the thermooxidative degradation/stability of the secondary structure of humic acids. It has been demonstrated that aromatic compounds added to humic acids, except pyridine, increased stability of humic acids and intermediate chars. The same conclusion can be drawn for acetic and palmitic acids. Addition of glucose or ethanol decreased the overall humic stability; however, the char of the former showed the highest stability after 40% of degradation. Springer Science+Business Media LLC, 2007 DSC nationallicence lignite humic acids nationallicence isoconversional methods nationallicence stability nationallicence Válková D. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut Kislinger J. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut Pekař M. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut Kučerík J. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 89/3(2007-09-01), 957-964 1388-6150 89:3<957 2007 89 10973 https://doi.org/10.1007/s10973-007-8437-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-007-8437-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Válková D. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut NATIONALLICENCE 700 1- Kislinger J. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut NATIONALLICENCE 700 1- Pekař M. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut NATIONALLICENCE 700 1- Kučerík J. BUT Faculty of Chemistry, Purkyñova 118, Brno, Czech Republic aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 89/3(2007-09-01), 957-964 1388-6150 89:3<957 2007 89 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer