The objective of this thesis is to aid in the development of Remedial Extraction And Catalytic Hydrodehalogenation (REACH), a green remediation technology used to remove and destroy halogenated hydrophobic organic compounds from soil. REACH has no secondary waste streams, uses an environmentally benign solvent, and aims to catalytically destroy rather than transfer the organic contaminants into a different phase. In this thesis, a bench-top semicontinuous model of the proposed remediation technology was constructed and used to extract the model contaminant, 1,2,4,5-tetrachlorobenzene, from soil and to convert it to an acceptable end product, cyclohexane. Palladium was used as a catalyst for hydrodehalogenation, which converted the tetrachlorobenzene to benzene. Rhodium was used to catalyze the hydrogenation of benzene to cyclohexane. A novel method, ultraviolet solvent treatment, was proposed to mitigate catalyst deactivation that occurs because of extracted chemicals contained in the contaminated soil. The goal of this treatment is to degrade organic matter that is suspected of causing catalyst deactivation. The REACH process was found to successfully extract TeCB from the soil, but only partial conversion from TeCB to cyclohexane occurred. Catalyst deactivation was the suspectedcause of the low amount of conversion observed. Hydrogen limitation was also tested as a cause of limited conversion, but was not found to be a contributor. Ultraviolet solvent treatment was tested as a means of mitigating catalyst deactivation. However, the treatment was not effective in making a profound difference in stopping the catalyst from deactivating. The experiments conducted in this research show that REACH has the potential to become a viable technology for cleaning soil contaminated with halogenated organic compounds. However, future research needs to be done to greatly reduce the severity of catalyst deactivation and to determine with which other halogenated organic compounds the technology works well.

The two objectives of this work were to develop a simplified method for the analysis of chlorinated organics in water samples and to improve an existing soil remediation technology. The contaminants considered for these studies were chlorinated hydrocarbons because of their relative frequency of appearance at contaminated sites. The first half of this study involved the analysis of chlorinated ethenes by gas chromatography with flame ionization detection (GC-FID). I tested the hypothesis that the FID response factor is the same for all chlorinated ethene compounds. The rationale for this investigation is that if the hypothesis is correct, a single calibration curve can be used for GC/FID analysis of all chlorinated ethene compounds, saving time and money during sample analysis. Based on my measurements, a single calibration curve fits PCE, TCE, and cis-DCE (R2=0.998). However, the apparent slope of the calibration curve for vinyl chloride is approximately 45% lower, indicating that a separate calibration curve must be used to quantify vinyl chloride. I believe this difference in vinyl chloride is due to loss of analyte mass due to volatilization. The second half of the study considered the effect of solvent composition for a soil remediation technology, entitled remedial extraction and catalytic hydrodehalogenation (REACH), developed by Dr. Hun Young Wee and Dr. Jeff Cunningham (Wee and Cunningham, 2008). The objective of this thesis is to convert 1,2,4,5-tetrachlorobenzene (TeCB) to cyclohexane, thus improving on the work of Wee (2007). Recent work by Osborn (2011) tested successfully the use of palladium and rhodium catalysts for this conversion, though it took twelve hours for full conversion. Osborn (2011) performed her experiments in a 50:50 water-ethanol solvent; previous work by Wee and Cunningham (2008) suggests that using a 67:33 water-ethanol composition may dramatically reduce the reaction time. Therefore, the goal of this research was to use palladium and rhodium catalysts with a 67:33 water-ethanol solvent composition, with an aim of reducing the reaction time required to fully convert benzene to cyclohexane. The data suggest that the time required for conversion of the analyte to its product was improved dramatically compared to previous experiments. However, powdered palladium catalyst was used in this study instead of pellet form as in previous studies. The powdered palladium allowed for full conversion of the target chemical, TeCB, to benzene in less than 5 minutes. Benzene was fully converted to cyclohexane within 45 minutes in the batch reactor when a rhodium catalyst was used jointly with palladium. This study suggests that the 67:33 water-ethanol solvent composition be utilized in continuous flow tests in the future to improve the efficiency of the REACH system. The results also suggest that powdered palladium catalyst be considered because of its ability to force the reaction to completion in significantly less time than previous experiments.

The objective of this research was to aid in the development of a new method for removing and destroying soil contaminants. In particular, 1,2,4,5-tetrachlorobenzene (TeCB) was selected for this research. Hydrodehalogenation (HDH) was paired with hydrogenation for remedially destroying TeCB without generating a secondary waste stream in a single batch reactor. Palladium- and rhodium-catalyzed HDH and hydrogenation were applied in a batch reactor at room temperature and moderate hydrogen pressure. Cyclohexane was formed as an end product with benzene as an intermediate reactant. An analytical method was developed to measure TeCB, benzene, and cyclohexane in a solution of water and ethanol, 50:50 by volume before mixing, by gas chromatography with electron capture detection (ECD) and flame-ionization detection (FID). Experimental data were consistent with a model in which dehalogenation and hydrogenation were considered sequential processes with first order reaction kinetics.