| Popis: |
A series of humic acid (HA) metal (Fe, Al) complexes were prepared and subjected to thermogravimetric and spectroscopic studies. The activation energies of decarboxylation were found to be 6–9 kcal/mole. H 2 O and CO 2 accounted for the main weight loss of HA and its complexes. No distinction could be made between organic and inorganic sources of water. Interaction of Fe 3+ with HA at a low pH probably causes reactions, such as oxidation of phenols to quinoids, transamination, decarboxylation etc. This is supported by i.r. spectroscopy and elemental analysis. It is assumed that humic acids fixed on clays might possess thermal properties similar to those of the HA oxidized by Fe 3+ at low pH. |
