Abstract

Polychlorinated biphenyls (PCBs) are synthetic organic chemicals that ca de detected in the environment worldwide. PCBs were banned in the U.S in 1979 owing to their toxicity and persistence in the environment. Today PCBs are classified as human carcinogens and are among the top ten of the U.S Environmental Protection Agency's (EPA) most toxic chemicals. Many researchers have shown soil to be contaminated with PCBs at concentrations as high as 750 ppm. Given the toxicity of PCBs, there is an urgent need to extract and degrade such chemicals from contaminated soil in a cost effective way. Prior work revealed a novel method of degradation of PCBs via hydrodehalogenation with zero-valent magnesium in acidified ethanol and ethyl lactate as a solvent system. Even though this degradation method gave satisfactory results for PCB degradation, this system cannot tolerate more than 3% water in order to degrade PCBs, limiting its application to wet soil field samples. In the present work a new system of acidified ethanol and ethyl lactate with ZVMg over activated carbon was developed which shows promising results on the degradation process of PCBs even with water present in the system. A detailed study of the byproducts formed in the dechlorination process and a degradation pathway, along with the activity of the system over time, are presented in this research. Also, a study of the mechanism involved in this reaction was done via computational methods to elucidate a mechanism pathway. It was demonstrated that these reactions are exothermic and involved two transition states, the formation of the first transition state being the limiting step of this reaction. The torsion angle of the PCB congeners was also shown to be an extremely important factor in order to be able to use activated carbon as part of the remediation process. These findings allow a greater understanding of the reductive dechlorination assisted by ZVMg and will help to improve the remediation process in field samples.

Notes

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Graduation Date

2016

Semester

Spring

Advisor

Yestrebsky, Cherie

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Chemistry

Degree Program

Chemistry

Format

application/pdf

Identifier

CFE0006205

URL

http://purl.fcla.edu/fcla/etd/CFE0006205

Language

English

Release Date

May 2016

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

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Included in

Chemistry Commons

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