Speciation of As, Cr, Se and Hg under coal fired power station conditions

Pushan Shah*, Vladimir Strezov, Kathryn Prince, Peter F. Nelson

*Corresponding author for this work

Research output: Contribution to journalArticle

137 Citations (Scopus)

Abstract

Coal combustion from power stations is an important anthropogenic contributor of toxic trace elements to the environment. Some trace elements may be emitted in range of valencies, often with varying toxicity and bioavailability. Hence, determination of trace element speciation in coals and their combustion products is important for conducting comprehensive risk assessments of the emissions from coal-fired power stations. This study focuses on speciation of selected trace elements, As, Cr, and Se, in coal combustion products and Hg in flue gas, which were sampled at one Australian power station. Different analytical methods such as secondary ion mass spectrometry (SIMS), ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS) and X-ray absorption near edge structure spectrometry (XANES) were used to determine trace element speciation in coal and ash samples. Results showed that As, Cr and Se are all present in a range of valency states in coal. Concentrations of As and Se in the bottom ash as well as the more toxic hexavalent chromium were less than the detection limits. The more toxic As3+ form in fly ash was at 10% of the total arsenic, while selenium was mainly found in Se4+ form. Hexavalent chromium (Cr6+) in fly ash was 2.7% of the total fly ash chromium. Mercury speciation in flue gas was determined using the Ontario Hydro sampling train and analysis technique. Approximately 58% of the total mercury in flue gas was released in the elemental form (Hg0), which, among all mercury species, has the highest residence time in the environment due to lower solubility. This work summarises the performance of the selected analytical techniques for speciation of trace elements.

Original languageEnglish
Pages (from-to)1859-1869
Number of pages11
JournalFuel
Volume87
Issue number10-11
DOIs
Publication statusPublished - Aug 2008

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