REGENERATED HUMIC ACIDS OBTAINED BY THE AIR OXIDATION OF SOUTH MORAVIAN LIGNITE. PART. 2. THERMOANALYTICAL CHARACTERIZATION OF PRODUCTS

článek v časopise - ostatní, Jost

angličtina

A sample of humic acid prepared from parental lignite and seven regenerated humic acids prepared from oxidized ones were extracted from South Moravian lignite. First, the samples were tested for their stabilities and degradabilities using thermogravimetry. It was shown that oxidation of lignite in static reactor at 85 C produced regenerated humic acids with an increasing content of labile part. The dependency of labile content was exponential-like and reached a constant value after 240 hours of oxidation. Increasing content of labile part in regenerated humic acids was also confirmed by measuring of heat accompanying the thermo-oxidative degradation using differential scanning calorimetry.The previously reported increase in number of ester bonds and the character of surface of prepared humic material was evaluated by moisture uptake measurement. Using thermogravimetry, the determination of the content of moisture adsorbed on the surface of humic samples after 21 days was carried out. In accordance with previous conclusions based on elemental analysis and yield of regenerated humic acids, the highest moisture content was observed for humic sample prepared in fluid reactor from lignite oxidized at 50 C for 72 hours and a sample extracted from lignite oxidized in static reactor at 85 C for 456 hours.

lignite oxidation; regenerated humic acids; moisture uptake; thermal degradation

CIHLÁŘ, Z.; KUČERÍK, J.

2010

23. 12. 2010

Slovnaft

Slovenská Republika

1335-3055

Petroleum and Coal

52

4

Slovenská republika

49

55

7