Daozhong Zou

Publication Date

8-2000

Advisor(s) - Committee Chair

Wei-Ping Pan, John Riley, Lowell Shank

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Degree Program

Department of Chemistry

Degree Type

Master of Science

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are semi-volatile organic compounds. This class of chemicals can be produced by most practical combustion systems and emitted with flue gas or adsorbed in combustion residues, such as fly ash and bed ash. Due to the potential toxicity of PAHs to the environment and human beings, analysis of PAHs has been a topic of interest for a long time. Particularly, the data on PAHs from coal combustion systems will provide valuable information for the disposal of post-combustion residues.

The purpose of this study was to develop a thermal extraction method for the analysis of the 16 US EPA specified priority PAH pollutants in fly ash from a 0.1 MWth bench scale fluidized bed combustor (FBC). The samples were analyzed using thermal extraction and fast gas chromatography/time-of-flight mass spectrometry (TE/GC/TOFMS). The analysis could be achieved in less than one hour. The results indicated that TE/GC/TOFMS had good linear range (15.30-481.82 ng PAH). The recoveries for the 16 target PAHs varied between 82.9% and 96.1%, while the method limits of detection varied between 0.35 mg/kg and 1.43 mg/kg.

For comparison, the same fly ash samples were tested by using both the TE/GC/TOFMS method and conventional Soxhlet extraction-GC/MS. The results from the two methods were comparable, but the concentration of a single PAH might be different due to the different behavior of PAHs in two methods.

In addition, the sample size upon extraction was studied. It showed that the sample size did have an impact upon the analysis results in both methods.

In supplemental testing, the effects of solvent volumes in the Soxhlet extraction were also investigated. The tests that solvent volume was a factor to be considered in the Soxhlet extraction process.

Disciplines

Chemistry | Physical Sciences and Mathematics

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