NONCATALYTIC OXIDATION OF WATER-SLURRIED COAL WITH OXYGEN - IDENTIFICATION OF FULVIC-ACIDS AND ACUTE TOXICITY

The composition and toxicity of the aqueous oxidation fraction of coal were investigated, to gain information concerning process safety meas ures and the utilization of the oxidation products as antibacterial ag ents. Coal was oxidized with oxygen at 180 degrees C under constant pr essure (4 MPa). Fractions of the crude filtrate obtained during this p rocess were sublimed, distilled and extracted with ether and ethanol. Almost 50 different acids were identified in these samples using g.c. and g.c.-m.s. analyses. The following groups of acids could be disting uished: (1) all possible unsubstituted acids containing up to four car bon atoms: (2) higher carboxylic acids containing even numbers of carb on atoms, agreeing with occurrence in nature; (3) oxygenated straight- chain or branched acids in the hydroxy or keto form containing up to s ix carbon atoms; (4) dicarboxylic aliphatic acids containing up to six carbon atoms; and (5) benzoic acid and its monohydroxy derivatives an d phthalic acid. No highly toxic compounds could be identified, most o f the compounds being common physiological metabolites. Primary acute toxicity studies were carried out on rats, using the crude aqueous sol ution and the drum-dried product of this solution. Apart from local ir ritation caused by their acidic nature, neither of these fractions exh ibited significant acute toxicity in the test animals. Copyright (C) 1 997 Elsevier Science Ltd.