MACROMOLECULAR STRUCTURE OF BROWN-COAL IN RELATIONSHIP TO THE DEGRADABILITY BY MICROORGANISMS

The macromolecular components of two humic brown coals of the same moo r-facies type, but different geological age were isolated, and their s tructures were subsequently characterized using solid-state C-13-NMR s pectra. The results were compared with the published C-NMR data of the macromolecular components of a brown coal which was rich in liptinite macerals. As to the humic coals, the proportion of the macromolecular components is smaller in the older coal than in the younger coal (65% and 85%, respectively). The NMR spectra show a structure which is rel ated to lignin structures. Quantitative differences are indicated by t he smaller proportions of aliphatic oxygen functionalities and the hig her proportions of alkyl groups in the older coal. The macromolecular components of the liptinitic brown coal represent a completely differe nt structural type: Their network has an aliphatic basic structure and is predominantly built up by linkage of methylene chains. Very differ entiated structural conditions exist for microbial depolymerization of the macromolecular structures of brown coals. (C) 1997 Elsevier Scien ce B.V.