Humic acids from oxidized coals I. Elemental composition, titration curves, heavy metals in HA samples, nuclear magnetic resonance spectra of HAs and infrared spectroscopy.

The formation of humic acids (HAs) from bituminous coal was verified by laboratory oxidation. In a relatively short time the oxidation by air at temperature above 150 degrees C led to the formation of HAs. These HAs were compared with those isolated from oxidized bituminous coal from the vicinity of red bed bodies, from weathered bituminous coal, oxihumolite and lignite.