Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Civil and Environmental Engineering

Supervisor

Dr. Denis O'Carroll

Abstract

1,2-Dichloroethane (1,2-DCA) is among the most prevalent groundwater chlorinated organic compounds (COCs) found at hazardous sites throughout the world. Given its pervasive contamination and adverse health effects, there is considerable interest in developing novel remediation technologies for successfully treating 1,2-DCA along with other COCs from water sources. Chemical reduction by nano zero valent iron (monometallic (nZVI) or bimetallic (Pd-nZVI)) has proven to be a successful field applicable technology, yet it has failed in degrading such a recalcitrant compound as 1,2-DCA.

In this study, the development of a field applicable nano metal based technology capable of degrading 1,2-DCA was carried out. For the first and the second studies, the feasibility of catalyzed dechlorination of 1,2-DCA using borohydride as a Hydrogen (H2) source over nano palladium (nPd) and nano copper (nCu) in the liquid phase at room temperature was investigated. Complete removal of 1,2-DCAin a matter of days or hours was achieved by either nPd or nCu particles coupled with borohydride. The novel dechlorination system produced mainly ethane as the dechlorination byproduct, without formation of toxic chlorinated intermediates. This phase also examined the influence of different experimental parameters including: metal loading, 1,2-DCA loading, nanoparticle synthesis parameters and groundwater solutes on the dechlorination kinetics. It was found that experimental parameters affect the chemical composition as well as oxidation state of the nanoparticles, which controls the dechlorination reaction rate. For the third study, the efficiency of the developed novel technology, along with nZVI, Pd-nZVI, and nZVI-dithionite in remediating a suite of COCs, including 1,2-DCA, in a groundwater sample from an industrial site in Australia was assessed. nZVI, Pd-nZVI, and nZVI-dithionite were able to break down COCs with the exception of 1,2-DCA. nZVI-dithionite was able to breakdown about 20% of 1,2-DCA. nPd or nCu coupled with borohydride degraded 55% and 94%, respectively, of 1,2-DCA along with complete removal of all other COCs. The presence of groundwater solutes was found to adversely affect dechlorination efficiency of the treatments.

Overall, this thesis presents a novel nano metal based remediation technology capable of reducing 1,2-DCA. The results suggest that the developed nano metal based technology can be an effective remediation approach for multi-COCs contaminated groundwater depending upon site conditions.

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