Correlation of humic substances chemical properties and their thermo-oxidative degradation kinetics
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Application of the Arrhenius equation as the temperature function in modeling of the degradation kinetics of humic substances brought a high positive Pearson correlation coefficient with the carbon content and a reasonable negative correlation with the oxygen content. Ratio C/H indicating the aromaticity degree of humic samples did not show any significant correlation. Relatively high value of correlation coefficients provided also O + N and ratios C/(O + N) and C/O, respectively. In contrast, H, N content and natural and heat generated free radical content and their ratio gave substantially lower correlation coefficients. The latter indicates that free radicals are probably not the main reason of the collapse of the secondary structure of humic substances leading to their degradation.
KeywordsHumic substances Isoconversional methods Single step approximation Correlation analysis Thermal analysis
The financial support of Grant Agency of the Czech Republic, Project 104/05/P513 and Ministry of Education, Project MSM 0021630501 are acknowledged.
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