CHARACTERIZATION OF BROWN-COAL HUMIC ACIDS AND MODIFIED HUMIC ACIDS USING PYROLYSIS GEMS AND OTHER TECHNIQUES

It has been proposed that Victorian brown coal can be considered as a two-component structure - a lignocellulosic ''host'', containing vario us amounts of weakly bound or entrapped ''guest'' material together wi th very small amounts of inorganic and/or mineral matter. The latter p redominantly consists of wax esters and/or terpenoid material. In this paper we describe attempts to gain structural information regarding t he more complex, ''host'' component of the coal. Our initial model com pound has been humic acid that can be readily obtained from the coal b y alkaline extraction. It has been found that ''pure'' humic acid, fre e from material associated with the ''guest'' components of the coal, can be obtained by a highly selective, low-yielding alkaline extractio n. This humic acid has been studied by nmr spectroscopy and pyrolysis gas chromatography-mass spectroscopy (py-gc/ms). The products arising from py-gc/ms have been compared with those obtained from similar pyro lysis of whole coals. Alkylation of humic acids using alkyl halides in the presence of base has been successfully carried out and reactivity of the resulting materials compared with those of the parent coal and humic acid.