Publication Date

2013

Document Type

Thesis

Committee Members

Abinash Agrawal (Advisor), Songlin Cheng (Committee Member), Mark Goltz (Committee Member)

Degree Name

Master of Science (MS)

Abstract

Chlorinated hydrocarbons (CHCs) in groundwater can be treated by monometallic and bimetallic metal reductants through abiotic degradation. The breakdown of CHC is achieved by gaining electrons from those reductants and removing chlorines from CHC molecules to transform the CHCs into less chlorinated compounds. As a proven technology in groundwater treatment, permeable reactive barriers (PRBs) have been used to passively treat contaminated groundwater, in which granular metals can be used as reactive materials. This study explored the abiotic degradation of CHCs by zero-valent magnesium (ZVM) and bimetallic palladium/magnesium (Pd/Mg) reductants. Different CHCs (carbon tetrachloride, chloroform, dichloromethane (DCM), 1,2-dichloroethane (1,2-DCA), 1,1,2-trichloroethane (1,1,2-TCA), 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA), 1,2-dichloropropane (1,2-DCP), and 1,2,3-Trichloropropane (1,2,3-TCP) were chosen as target contaminants. Results showed that even with its high reduction potential, ZVM did not treat CHCs effectively due to corrosion of Mg by water, which formed Mg (OH)2(s) precipitate on the metal surface and prevented further reaction. Such inhibition can be reduced by lowering pH conditions. However, in the presence of Pd, CHCs were removed at a much faster rate at neutral pH conditions. Hydrocarbons were produced as sole products, which indicated complete degradation of CHCs by Pd/Mg. Recalcitrant CHCs such as DCM, 1, 1,2-TCA, 1,2-DCP and 1,2,3-TCP were found to be effectively degraded by Pd/Mg. No significant effect of Pd loading on CHC degradation was observed, while the degradation was accelerated by increasing the Mg loading.

Page Count

82

Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded

2013

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