Chemical composition and toxicological activity of liquefaction materials derived from different feed coal ranks

Samples of recycle solvent from the bottoms recycle mode of the EDS direct coal liquefaction process using bituminous, sub-bituminous, and lignite coal feeds were chemically characterized and tested for toxicological response. The H-Coal heavy fuel oils derived from bituminous and sub-bituminous coals were also analyzed. Chemical methods of analysis included adsorption column chromatography, high-resolution gas chromatography, gas chromatography/mass spectrometry, and low-voltage probe-inlet mass spectrometry. The toxicological activity of selected samples was evaluated using the standard histidine reversion microbial mutagenicity assay, an initiation/promotion assay for mouse-skin tumorigenicity, and a static bioassay with Daphnia magna for aquatic toxicity of the water-soluble fractions. Both materials derived from the bituminous coals had the following chemical characteristics as compared to their sub-bituminous coal and/or lignite-derived counterparts: higher concentrations of polycyclic aromatic hydrocarbons (PAH), nitrogen-containing polycyclic aromatic compounds, and hydroxy-substituted PAH; lower concentrations of aliphatic hydrocarbons; and a generally increased molecular weight distribution of approximately ten atomic mass units. Toxicological testing indicated a general trend of increased biological activity of the coal liquefaction products with increasing feed coal rank.