25th International Meeting on Organic Geochemistry IMOG 2011

P-144
Organic compounds of geochemical origin in domestic furnaces
coal ash (Upper Silesia, Poland)
Monika Fabiańska, Danuta Smołka-Danielowska
University of Silesia, Sosnowiec, Poland (corresponding author:monika.fabianska@us.edu.pl)
Coal combustion generates a great amount of ash
exceeding 550 . 10 6 tonnes/year worldwide. While in
power plants most of ash is collected in cyclones, in
domestic combustion finer fractions of ash are emitted
to the air or dumped out without any control. Due to
its adsorbing properties coal ash can contain organic
compounds deriving from parent coal or formed in
burning. Since domestic coal combustion is the most
hazardous to the environment it is important to find
what biomarker distributions are characteristic for this
emission source. In future, these results may help to
distinguish the domestic combustion input to organic
pollution and to the general background of organic
compounds present in the urban air. The research
aim was: (i) to establish what organic compounds are
present in coal ash from domestic furnaces, (ii) to find
their source, and (iii) to assess changes in biomarker
distribution caused by combustion.
Coal ash was sampled in two domestic furnaces
using Upper Silesia coals (Poland) for central heating,
located in the Orzesze and Piekary Śląskie towns.
Analyses comprised ash ultrasonic extraction and gas
chromatography–mass spectrometry (GC–MS) of the
total extracts.
Ash extract yields were in the range 0.002-0.032
% (wt.). Aliphatic hydrocarbons dominate in extracts
chemical composition, particularly n-alkanes. Lightweight
compounds were not common, with the
Orzesze domestic coal ash more often containing
them than the Piekary Śląskie ash extracts. All coal
ash extracts show a monomodal distribution of nalkanes
in the range from n-C13 to n-C35 without oddover-even
carbon number atom predominance
(CPI~1.0). Long-chain n-alkanes predominate over
lighter compounds. Values of pristane/phytane ratio
are > 1.00 in the Orzesze ash extracts while the
Piekary Śląskie extracts show more various
distributions, with these compounds absent in many
samples. Pentacyclic triterpanes are present in the
range from 18α(H)-22,29,30-trisnorneohopane (Ts) to
trishomohopanes (C33). The distribution is mature in
almost all Orzesze extracts, however, in some cases
it is thermally degraded. Only a few Piekary ash
extracts contained pentacyclic triterpanes. Steranes
occur in few samples and in very low concentrations.
This feature is inherited from the source Upper Silesia
coals in which steranes are often absent or present in
low amounts. Stigmastanes dominate whenever
steranes are present in extracts. Polycyclic aromatic
hydrocarbons comprised compounds with 2-5
aromatic rings unsubstituted and substituted with C1-
C4 alkyl groups, with naphthalene occurring in low
amounts or absent, and phenanthrene showing the
highest concentrations. Also polar compounds were
found mainly phenol and its derivatives (4methylphenol,
4-propylophenol, 3,4- and 3,5dimethylphenol).
These compounds probably come
from thermal destruction of vitrinite macromolecule or
conifer wood applied together with coal since phenolic
units are considered to be of lignin origin [1].
Due to relatively low combustion temperatures in
domestic furnaces (270 o C) and incomplete
combustion many biomarkers from the parent coal
survived the process. Their distributions are
unchanged or only slightly changed by heat and show
features of the source fuel, i.e. bituminous coal of the
Upper Silesia Coal Basin [2]. Such compounds as
steranes, or pentacyclic terpanes obviously come
from unburnt particles of coal. Compounds
considered to be formed in combustion are minor
components of ash extracts. Two series of samples
differ due to slightly higher temperature of the Piekary
Śląskie furnace and better oxygenation of its coal
combustion zone.
[1] Hatcher P.G., Faulon J-L., Wenzel K.A., Cody
G.D. 1992. A structural model for lignin-derived
vitrinite from high-volatile bituminous coal
(coalified wood), Energy & Fuels, 6, 813-820.
[2] Kotarba M.J., Clayton J.L. 2003. A stable carbon
isotope and biological marker study of Polish
bituminous coals and carbonaceous shales.
<strong>International</strong> Journal of Coal Geology, 55, 73-94.
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