Thesis (M.S.)--University of Kentucky, 2003. / Title from document title page. Document formatted into pages; contains x, 163 p. : ill. Includes abstract. Includes bibliographical references (p. 151-161).

The work summarizes the results of a studies conducted with six different flushing agents, i.e. two anionic surfactants (SDS and DOWFAX 8390), two complexing agents (cyclodextrins), a humid acid, and an alcohol (ethanol), for solubilizing and removing residual-phase immiscible liquid from porous media. Batch experiments were conducted to measure the degree of trichloroethene (TCE) and tetrachloroethene (PCE) solubilization induced by these agents. These studies revealed that the solubility of TCE and PCE was enhanced significantly. Column experiments were conducted to compare water and agent-enhanced flushing of Borden sand containing residual saturations of TCE and PCE. The results of these studies indicate that the total flushing volume necessary to remove the contaminant was reduced substantially in the presence of all applied agents. The relative effectiveness of the agents varied based on the method of evaluation. It was shown that a volatile contaminant, e.g. toluene, TCE, and PCE, can be separated from cyclodextrin solution by mean of air-sparging. The cyclodextrin solution was successfully reused for continuos flushing of a contaminated porous material. The simulation of selected experiments revealed that the mass transfer rate coefficients are generally increasing if evaluated based on the aqueous driving force approach. However, a relation based on the enhanced driving force approach was found to be less significant. Even though areas of additional research have been identified, this research contributes to a better understanding of the processes governing chemically enhance flushing of contaminated porous media.

Trichloroethylene (TCE) is among the most common water contaminant in the United States and around the world. It is estimated that between 9% and 34% of all drinking water sources contain some TCE. The EPA set a drinking water standard for TCE at 5 parts per billion (ppb) in 1989, however since this date, many studies have shown TCE is dangerous to the health of adults and unborn children, even at low-level exposures. These studies reveal exposure to TCE can cause multi-organ damage, especially for the kidney, liver, reproductive and development systems. We investigated how TCE can effect embryonic heart development by identifing possible target mechanisms changing after exposure. Acute and chronic exposure to rat cardiomyocytes produced altered calcium flow and significant changes with TCE doses as low as 10ppb. Embryonic carcinoma cells, rat cardiomyocytes and fetal heart tissue all showed global changes in gene expression after low-dose TCE exposure, including critical ion channels that drive calcium flux. High levels of folic acid supplementation in combination with 10ppb TCE exposure in maternal diets caused significant genetic modifications in mRNA expression levels of Day 10 embryonic mouse cardiac tissue. We also found both high and low folate maternal diets leads to similar phenotypic outcomes in embryo development.

The current treatment of water contaminated with organic compounds includes adsorption, air stripping, and advanced oxidation processes. These methods large quantities of water and require excessive energy and time. A novel treatment process of concentrating and then electrochemically oxidizing compound would be a more feasible practice. This research investigated the oxidative destruction of perfluorooctane sulfonate (PFOS), perfluorobutane sulfonate (PFBS) and trichloroethene (TCE) at boron-doped diamond film electrodes and the adsorption of PFOS and PFBS on granular activated carbon and ion exchange resins.Experiments measuring oxidation rates of PFOS and PFBS were performed over a range in current densities and temperatures using a rotating disk electrode (RDE) reactor and a parallel plate flow-through reactor. Oxidation of PFOS was rapid and yielded sulfate, fluoride, carbon dioxide and trace levels of trifluoroacetic acid. Oxidation of PFBS was slower than that of PFOS. A comparison of the experimentally measured apparent activation energy with those calculated using Density Functional Theory (DFT) studies indicated that the most likely rate-limiting step for PFOS and PFBS oxidation was direct electron transfer. The costs for treating PFOS and PFBS solutions were compared and showed that PFOS is cheaper to degrade than PFBS.Screening studies were performed to find a viable adsorbent or ion exchange resin for concentrating PFOS or PFBS. Granular activated carbon F400 (GAC-F400) and an ion exchange resin, Amberlite IRA-458, were the best methods for adsorbing PFOS. Ionic strength experiments showed that the solubility of the compounds affected the adsorption onto solid phases. Regeneration experiments were carried out to determine the best method of recovering these compounds from the adsorbents; however, the compounds could not be effectively removed from the adsorbents using standard techniques.The electrochemical oxidation of trichloroethene (TCE) at boron-doped diamond film electrodes was studied to determine if this would be a viable degradation method for chlorinated solvents. Flow-through experiments were performed and showed TCE oxidation to be very rapid. Comparing the data from the DFT studies and the experimentally calculated apparent activation energies the mechanism for TCE oxidation was determined to be controlled by both direct electron transfer and oxidation via hydroxyl radicals.

Trichloroethylene, a simple and very inexpensive material, has been identified as a tri- and tetrafunctionalizable building block. A combination of selective palladium-catalyzed cross-coupling reactions with standard lithiation and electrophilic quenching yields a wide variety of unsaturated linear or cyclic compounds in excellent yields in few synthetic steps. Dichlorovinyl ethers, obtained from a nucleophilic displacement reaction with trichloroethylene, are the basic starting materials. Two sets of conditions have been developed to achieve the reaction of either electron-rich or –deficient phenols with trichloroethylene to give the resultant dichlorovinyl ethers in high yields. Site selective palladium-catalyzed cross-coupling for the specific functionalization of a single C-Cl bond was developed, and could install alkyl, alkenyl, alkynyl and (hetero)aryl moieties. The resulting electrophiles could be reacted with a second organometallic nucleophile forming trisubstituted, electron-rich alkenes, dienes, trienes or enynes in only two or three steps. Alternatively, the product from the first cross-coupling reaction could be isolated, deprotonated and quenched with an electrophile, then cross-coupled with a second organometallic nucleophile to give tetrasubstituted, electron-rich alkenes and dienes. In the course of studying the site selective cross-coupling, it was found that prolonged exposure of the C1-functionalized materials to palladium promoted an intramolecular C-H activation, forming 2-substituted benzofurans. This reaction proved to be very general, and a wide variety of benzofurans were synthesized, containing both electron-withdrawing and electron-donating group groups in the donor arenes, as well as alkyl, alkenyl, alkynyl and aryl functionalities at the 2-position. This method was also extended to the synthesis of 2-substituted indoles from anilines, trichloroethylene and boronic acids.

Trichloroethylene, a simple and very inexpensive material, has been identified as a tri- and tetrafunctionalizable building block. A combination of selective palladium-catalyzed cross-coupling reactions with standard lithiation and electrophilic quenching yields a wide variety of unsaturated linear or cyclic compounds in excellent yields in few synthetic steps. Dichlorovinyl ethers, obtained from a nucleophilic displacement reaction with trichloroethylene, are the basic starting materials. Two sets of conditions have been developed to achieve the reaction of either electron-rich or –deficient phenols with trichloroethylene to give the resultant dichlorovinyl ethers in high yields. Site selective palladium-catalyzed cross-coupling for the specific functionalization of a single C-Cl bond was developed, and could install alkyl, alkenyl, alkynyl and (hetero)aryl moieties. The resulting electrophiles could be reacted with a second organometallic nucleophile forming trisubstituted, electron-rich alkenes, dienes, trienes or enynes in only two or three steps. Alternatively, the product from the first cross-coupling reaction could be isolated, deprotonated and quenched with an electrophile, then cross-coupled with a second organometallic nucleophile to give tetrasubstituted, electron-rich alkenes and dienes. In the course of studying the site selective cross-coupling, it was found that prolonged exposure of the C1-functionalized materials to palladium promoted an intramolecular C-H activation, forming 2-substituted benzofurans. This reaction proved to be very general, and a wide variety of benzofurans were synthesized, containing both electron-withdrawing and electron-donating group groups in the donor arenes, as well as alkyl, alkenyl, alkynyl and aryl functionalities at the 2-position. This method was also extended to the synthesis of 2-substituted indoles from anilines, trichloroethylene and boronic acids.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on Oct. 7, 2009). Includes bibliographical references.

Objective: The Paducah Gaseous Diffusion Plant (PGDP) became operational in 1952; it is located in the western part of Kentucky. We conducted a mortality study for adverse health effects that workers may have suffered while working at the plant, including exposures to chemicals. Materials and Methods: We studied a cohort of 6820 workers at the PGDP for the period 1953 to 2003; there were a total of 1672 deaths to cohort members. Trichloroethylene (TCE) is a specific concern for this workforce; exposure to TCE occurred primarily in departments that clean the process equipment. The Life Table Analysis System (LTAS) program developed by NIOSH was used to calculate the standardized mortality ratios for the worker cohort and standardized rate ratio relative to exposure to TCE (the U.S. population is the referent for age-adjustment). LTAS calculated a significantly low overall SMR for these workers of 0.76 (95% CI: 0.72-0.79). A further review of three major cancers of interest to Kentucky produced significantly low SMR for trachea, bronchus, lung cancer (0.75, 95% CI: 0.72-0.79) and high SMR for Non-Hodgkin's lymphoma (NHL) (1.49, 95% CI: 1.02-2.10). Results: No significant SMR was observed for leukemia and no significant SRRs were observed for any disease. Both the leukemia and lung cancer results were examined and determined to refect regional mortality patterns. However, the Non-Hodgkin's Lymphoma finding suggests a curious amplification when living cases are included with the mortality experience. Conclusions: Further examination is recommended of this recurrent finding from all three U.S. Gaseous Diffusion plants.

Trichloroethylene (TCE) is a carcinogenic, chlorinated volatile organic compound that was commonly used as a degreasing solvent for aircraft maintenance at many US Air Force bases. Past improper disposal of TCE has resulted in contaminated groundwater at many of these facilities. Phytoremediation, defined as the use of plants and their associated microorganisms to stabilize or remove contamination, has been implemented as part of a TCE groundwater cleanup at Travis Air Force base near Sacramento, CA and is being considered as a remediation option at other bases. Volatilization of TCE from leaves and the surface of the soil near the trees were shown to be the most important removal mechanisms at the Travis site. Past studies conducted on indigenous trees growing above TCE contaminated groundwater at several Hill Air Force Base (HAFB) locations have also shown that TCE is taken up and volatilized by the trees. However, phytoremediation has not been implemented, in part because of the difficulty in predicting the potential effectiveness of TCE removal over time. Flow through or recirculating chambers were used to quantify the amount of TCE removed by volatilization through leaf, trunk, and soil surfaces. Tenax™ sorbent tubes, used to collect TCE from the chambers, were analyzed by thermal desorption gas chromatography/mass spectrometry. Tree cores were collected using an incremental borer and analyzed by headspace GC/MS to quantify the TCE mass contained in the trees. Field measured transpiration stream concentrations (TSC) and groundwater data were used to calculate transpiration stream concentration factors (TSCF) for TCE. Comparing current and historical data, it was found that trees reach a steady state TSCF value of 0.26 after about 15 years. Using this information, it was predicted that a phytoremediation plot containing 40 poplar trees located in a seep area within HAFB OU2 would remove 4.82 kg of TCE annually. A larger plot covering the entire hillside above this seep (160 trees) could remove up to 19.28 kg of TCE annually, once trees reach a steady state TSCF.

In situ chemical oxidation is a promising technology for the remediation of persistent subsurface contamination. Increasingly, the persulfate ion is being studied for use in these systems, both on its own as a strong oxidant and as the precursor to the even more reactive sulfate radical. Persulfate has been shown to treat a wide range of contaminants, from traditional Superfund contaminants such as chlorinated solvents to emerging pharmaceutical contaminants. Additionally, persulfate ISCO can be tailored to site and pollutant specific characteristics based on the method of persulfate activation (e.g., energy and catalysis activation) to the sulfate radical. Thermal activation of persulfate is particularly promising because it can be easily controlled, requires no additional reagents, and commonly creates only non-toxic end products. While persulfate in-situ chemical oxidation technology is being commercially used, a mechanistic study of the physical and chemical processes controlling the effectiveness of this remedial approach is not well documented in the literature. Published work characterizing persulfate ISCO largely focuses on reactions in aqueous, batch systems, which fail to provide crucial design data when working with ever transient, multi-phase groundwater systems. The purpose of this research was twofold. Initial studies characterized the overall transport behavior of unactivated and thermally-activated persulfate (20, 60, and 90°C) in one-dimensional soil column systems packed with a natural sandy porous media. This necessitated the development of a flow-through, temperature-controlled, continuous-injection system for the delivery of heat-activated persulfate. Finally, as a proof of concept, experiments were conducted to investigate persulfate ISCO as a remedial approach for residual-phase trichloroethylene (TCE), a commonly detected, persistent subsurface contaminant. At all activation temperatures investigated, persulfate exhibited ideal transport behavior with negligible differences in the observed breakthrough curves of persulfate ion and nonreactive tracers in miscible displacement experiments. Additionally, moment analysis of the breakthrough curves measured for persulfate ion in solution indicated negligible interaction of persulfate with the sandy material under steady-state flow (average retardation factor equaled 1.00 ± 0.021). Persulfate ISCO for residual-phase trichloroethylene (TCE) was characterized at two flow rates, 0.2 mL/min and 0.5 mL/min, resulting in two degrees of apparent persulfate activation, 39.5% and 24.6%, respectively. Both ISCO soil column systems showed an initial, long-term plateau in effluent concentrations measured for TCE indicating steady-state dissolution of pure phase TCE. Effluent concentrations of TCE began decreasing after 75 and 100 pore volumes (normalized for the residual fraction of TCE in individual soil columns) in the 39.5% and 24.6% activated persulfate columns as compared to 110 pore volumes in the control study (flushed with electrolyte only). Pseudo first-order rate constants for the decreasing TCE concentrations were calculated using log-linear regression analysis. The measured reaction rate constants for the control, the 0.2 mL/min (39.5% activation) study, and the 0.5 mL/min (24.6% activation) study equaled 0.044, 0.063, and 0.083 hr-1, respectively. Additionally, moment analysis of the complete dissolution of TCE in the persulfate/activated persulfate remediation systems indicated approximately 33% degradation/oxidation of TCE mass present. As shown by this and other work, persulfate has enormous potential as a subsurface remediation technology. A more thorough understanding of the physical and chemical mechanisms controlling the behavior and application of persulfate in the subsurface, especially under transient conditions, is necessary for the growth of this technology. By characterizing heat-activated persulfate under dynamic conditions, describing the overall transport of persulfate/activated persulfate in a natural porous media, as well as a proof of concept for the ISCO treatment of a residual nonaqueous phase liquid, this work aids in improving the implementation of persulfate ISCO systems.