Humic acids from coals of the North-Bohemian coal field I.: Preparation and characterisation

Humic acids were prepared from young North-Bohemian brown coals using alkaline extraction, sedimentation I filtration and acidic precipitation; membrane separations were applied to refine some preparatives. Samples were characterised by chemical analyses, molecular mass distribution, E4/E6 coefficient, IR spectra, C-13-NMR spectra and EPR spectra. The properties of the coal-derived humic acids were compared with the properties of humic acids prepared from chernozem and peat and with the properties of a commercially available humic acid from Fluka. (C) 2001 Elsevier Science B.V. All rights reserved.