Biomarker compounds in ash from coal combustion in domestic furnaces (Upper Silesia Coal Basin, Poland)

Abstract

Organic compounds occurring in coal ash of known mineralogy were investigated. Ash came from two domestic furnaces using bituminous coal from the Upper Silesia Coal Basin. Dichloromethane extracts of ash were analyzed with gas chromatography–mass spectrometry (GC–MS) for biomarkers from fuel and formed during combustion. Distributions of aliphatic hydrocarbons, aromatic and polar compounds were researched. Results were compared with those found for power plant coal ash, coal wastes which underwent self-heating and source bituminous coal. It was found that geochemical features of plant coal ash organic matter reflects mainly geochemistry of source bituminous coal. Several groups of biomarkers such as as n-alkanes, steranes and pentacyclic triterpanes show distributions recognizable as coal-deriving what enables to identify source fuel. Values of most biomarker and aromatic hydrocarbon parameters show minor changes due to heat of the combustion process. The most advanced changes are found in distributions of alkylnaphthalenes, pristane, phytane and lighter n-alkanes reflected by values of Pr/Ph, Pr/n-C17 and Ph/n-C18 ratios. Much less extensive changes are seen in distributions of pentacyclic triterpanes which make them the most useful biomarker group for source fuel characterisation. Most of biomarkers are probably present in coal ash in unburnt coal particles occurring in ash due to low temperature in domestic furnaces favoring organic matter preservation.