Date of Award

7-22-1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

David C. Tilotta

Abstract

Soil contaminated by petroleum hydrocarbons is a very serious environmental problem. In conventional methods such as Soxhlet and Sonication, toxic halogenated solvents such as Freon-113 or CH3Cl are used for the extraction of these pollutants and GC-FID or GC-MS for detection. This dissertation will focus on both the development of non-toxic alternatives to conventional solvents for the extraction and new detection methods. Method 1. On-line dynamic CO2 SFE-IR spectrometry using a fiber optic filter photometer. The research will involve the construction of an IR cell, CO2 SFE coupling with an IR photometer, determination of detection limit and the determinations of total petroleum hydrocarbons “TPH” in real-world soil samples. The pollutants will be extracted in supercritical (SC) CO2 and then will be detected by an on-line IR spectrometer. This dynamic extraction will be better than static extraction in previous work.Method 2. On-line Ar SFE-inductively coupled plasma (ICP) atomic emission spectrometer (AES). The research will involve: (1) determinations of extraction efficiencies in SC argon, (2) optimization of extraction conditions, (3) an argon SFE interfacing to the ICP-AES, and (4) the determinations of the TPH in real-world soil samples. All of the extracts will be introduced into the plasma directly and analyzed using selected element emission lines after extraction in SC argon. It is expected that the extraction efficiencies in SC argon should be similar to that in SC carbon dioxide, because argon and carbon dioxide are similar in polarity and density. An Ar SFE/ICP-AES will eliminate plasma blowout, noisy baseline, and CO2 interference as would happen in a CO2 SFE/ICP-AES. This work will show that on-line SFE using optical spectroscopic detection eliminates toxic solvents for the extraction and the loss of volatiles. The figures of merit in these methods are similar to that in standard methods.

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