Groundwater at Oak Ridge National Laboratory's Field Research Center (FRC) is contaminated with U(VI) and Tc(VII), has pH values as low as 3.3, and nitrate concentrations as high as 120 mM. The objective of this research was to determine if in-situ bio-immobilization is a viable treatment alternative for this water. A laboratory column packed with crushed limestone and bicarbonate was used to model in-situ pH adjustment. Denitrification and metal reduction were modeled in columns packed with FRC sediment with ethanol as the electron donor. Two intermediate-scale physical models deployed in the field were packed with limestone and sediment and were stimulated with ethanol to support denitrification, U(VI) reduction, and Tc(VII) reduction of FRC groundwater. The limestone/bicarbonate column maintained a pH of above 5 for nearly one hundred pore volumes without significant loss in hydraulic conductivity. The high-nitrate (~120 mM) column study provided rates of denitrification (~15.25 mM/day), ethanol utilization (~13 mM/day), and technetium reduction (~120 pM/day) by sediment microorganisms, but no uranium reduction was detected. Results of the low nitrate (3 mM) column study indicate that once the pH of FRC water is adjusted to pH ~7 and nitrate is removed, uranium (~3 μM) and technetium (~500 pM) reduction occurred with ethanol as the electron donor at rates of 0.5 μM/day and 57 pM/day. Similar results were obtained in two intermediate-scale (~3 m long) physical models. Data from the high-nitrate, low-pH model indicate that the pH was increased and nitrate and technetium reduction were occurring. Decreased U(VI) concentrations were measured in the presence of high nitrate concentrations. Thus, U(VI) precipitates may form or sorption of U(VI) may occur near the inlet in the pH adjustment region. The maximum pseudo-first order rates of reduction measured during the seventh week of model operation were: nitrate at 0.76 day⁻¹, Tc(VII) at 0.28 day⁻¹, and U(VI) at 0.12 day⁻¹. Ethanol concentrations were reduced from ~180 mM to zero in ~10 days during the seventh week of model operation. No Fe(II) production was measured. Concentration data collected from the low nitrate, neutral pH model indicate that nitrate, uranium, and technetium reduction were occurring, though the model had been operational for only ~6 weeks. No Fe(II) production was detected but sulfate reduction was occurring. The results of the laboratory experiments and the performance of the intermediate-scale physical models suggest that bio-immobilization is a viable treatment alternative for the contaminated groundwater at the FRC. / Graduation date: 2004

En aquest treball es descriu la síntesi de tres noves fosfines ambifíliques hidrosolubles (CH3)3C-CH2-C(CH3)2-Ph-(OCH2CH2)n-P(Ph)CH2CH2SO3Na (amb n= 1 (1), 5 (2)), Ph2PCH2CH2CH2P(Ph)CH2CH2-SO3Na (3), les quals varen ser caracteritzades per tècniques de ressonància magnètica nuclear de 1H, 13C i 31P, i per espectrometria de masses electrosprai.S'ha estudiat la reacció d'hidroformilació d'olefines superiors amb catalitzadors de rodi en sistemes bifàsics amb onze lligands ambifílics. Tot i que amb un dels lligands es va obtenir un elevat percentatge de conversió, la presència de metall en la fase orgànica impossibilita l'ús d'aquests lligands en processos industrials. Un estudi sintètic paral·lel en condicions d'hidroformilació va permetre caracteritzar la formació del complex [RhH(CO)L3] (L=fosfina ambifílica) a partir del precursor [Rh(acac)(CO)2].Estudis de complexació de les fosfines ambifíliques amb pal·ladi(II) han portat a la caracterització de complexos d'estequiometria [PdCl2L2]. A partir d'aquests estudis s'han obtingut per primera vegada dades experimentals que indiquen la coordinació del grup sulfonat de les fosfines al pal·ladi.Es varen efectuar estudis d'agregació de les fosfines ambifíliques i dels seus respectius complexos de pal·ladi. Mitjançant mesures de tensió superficial es va confirmar el caràcter tensioactiu de (1) i (2) i del complex [PdCl2(2)2]. Es va obtenir en cada cas el valor de la concentració micel·lar crítica. Per tal de visualitzar els agregats formats es varen estudiar solucions aquoses d'alguns dels lligands ambifílics i els seus complexos de pal·ladi per microscòpia electrònica usant la tècnica de la criofractura. L'estructura dels agregats no va poder ser caracteritzada completament mitjançant aquest mètode, probablement a causa de que es formarien principalment micel·les, les quals són massa petites per ser observades a través del microscopi electrònic.Finalment s'han realitzat estudis de radiocompostos de 99m-Tecneci per tal de ser aplicats en medicina nuclear com a radiofàrmacs. Es va estudiar la formació de radiocompostos amb les fosfines ambifíliques mitjançant diferents mètodes cromatogràfics. Es va estudiar la biodistribució del radiocompost format amb la difosfina (3) en una rata de laboratori, mostrant una acumulació preferencial en el ronyó i el fetge. Paral·lelament es va realitzar un estudi sintètic de complexos homòlegs de reni no radioactius. En aquest cas es va poder caracteritzar, mitjançant 31P-RMN, la formació del complex octaèdric [ReO2(3)2] on el lligand difosfina actua com a quelat. Es va poder comprovar la dificultat per obtenir complexos octaèdrics d'estructura semblant amb lligands monofosfina. / The synthesis of the following three new water soluble amphiphilic phosphines is described (CH3)3C-CH2-C(CH3)2-Ph-(OCH2CH2)n-P(Ph)CH2CH2SO3Na (n = 1 (1), 5 (2)), Ph2PCH2CH2CH2P(Ph)CH2CH2-SO3Na (3). These phosphines were characterized by 1H, 13C and 31P nuclear magnetic resonance, and electrospray mass spectrometry.The hydroformylation reaction of higher olefines with rhodium catalysts in two-phase systems with eleven amphiphilic ligands was studied. Although a high conversion was observed with one ligand, the use of these ligands in industrial processes was disabled because the catalyst was partially soluble in the organic phase. A synthetic study under hydroformylation conditions allowed to characterize the complex [RhH(CO)L3] (L= amphiphilic phosphine) starting from the precursor [Rh(acac)(CO)2].Complexation studies of the amphiphilic phosphines with palladium(II) allowed to the characterization of [PdCl2L2] complexes. As far as we know, these studies supplied the first experimental data points to the coordination of the sulphonate group to the metal in phosphine ligands with the ethylsulphonate fragment.Aggregation studies of the amphiphilic phosphines and their respective palladium complexes were carried out. Superficial tension measures confirmed the tensioactive character of (1), (2) and the complex [PdCl2(2)2]. The critical micellar concentrations were determined.Aqueous solutions of some amphiphilic ligands and their palladium complexes were studied by transmission electron microscopy (TEM) using the freeze-fracture technique in order to visualize the formed aggregates. The structure of the aggregates could not be fully characterized by this method, probably because micelles were mainly formed and they are too small to be characterized by this technique.Finally, synthetic studies of 99m-Technecium radiocompounds for nuclear medicine applications as radiopharmaceuticals were carried out . The formation of radiocompounds with the amphiphilic phosphines was studied by means of TLC methods. The bio-distribution of the radiocompound formed with the diphosphine (3) was studied in a rat, showing a preferential accumulation in kidney and liver. A synthetic study with the homologous non radioactive rhenium complex was carried out. The octahedral complex [ReO2(3)2]- was characterised by 31P NMR data and the results are consistent with the chelation of the diphosphine ligand acts to the metal. The synthesis of similar octahedral complexes with monophosphine ligands was unsuccessful.

Stainless steel – zirconium alloys were developed by the US Department of Energy Laboratories as metallic waste forms for noble metal fission products. This thesis evaluates iron–zirconium–rhenium alloys to establish a technical basis for using metal waste form alloys for technetium-99 immobilization. Rhenium is used as a surrogate for Tc-99 since Tc is not naturally available and Re is metallurgically similar to Tc. The iron-zirconium system has two eutectic compositions, Fe-15 wt % Zr and Zr- 16 wt% Fe. Ten test samples were successfully cast in yttrium oxide crucibles at 1600°C, half near each eutectic composition, with Re amounts varying from 2.5 to 12.5 weight percent. A scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS) capability was employed to determine the phase structure and phase composition of each sample. Iron rich samples were found to form up to three phases, with the rhenium content favoring the intermetallic phases: 1) an Fe solid solution phase, 2) an FeZr2-type intermetallic with 11 wt % or less Re, and 3) a second intermetallic with about 18 wt % Re. Zirconium rich samples formed as many as five distinct phases: 1) a Zr solid solution phase, 2) a Zr3Fe-type intermetallic with as much as 13 wt% Re, 3) a rhenium-zirconium intermetallic, 4) another Fe-Zr intermetallic with very little Re, and 5) a Fe-Re intermetallic. Potentiostatic and potentiodynamic electrochemical tests were performed using sulfuric acid to evaluate the corrosion resistance of each sample. These tests found that the zirconium rich samples were very corrosion resistant but became increasingly susceptible at higher rhenium concentrations. The iron rich samples were not very resistant to corrosion under the test conditions; there was no notable trend in corrosion behavior related to the introduction of rhenium.

Stainless steel - zirconium alloys were developed by the US Department of Energy Laboratories as metallic waste forms for noble metal fission products. This thesis evaluates iron-zirconium-rhenium alloys to establish a technical basis for using metal waste form alloys for technetium-99 immobilization. Rhenium is used as a surrogate for Tc-99 since Tc is not naturally available and Re is metallurgically similar to Tc. The iron-zirconium system has two eutectic compositions, Fe-15 wt % Zr and Zr- 16 wt% Fe. Ten test samples were successfully cast in yttrium oxide crucibles at 1600°C, half near each eutectic composition, with Re amounts varying from 2.5 to 12.5 weight percent. A scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS) capability was employed to determine the phase structure and phase composition of each sample. Iron rich samples were found to form up to three phases, with the rhenium content favoring the intermetallic phases: 1) an Fe solid solution phase, 2) an FeZr2-type intermetallic with 11 wt % or less Re, and 3) a second intermetallic with about 18 wt % Re. Zirconium rich samples formed as many as five distinct phases: 1) a Zr solid solution phase, 2) a Zr3Fe-type intermetallic with as much as 13 wt% Re, 3) a rhenium-zirconium intermetallic, 4) another Fe-Zr intermetallic with very little Re, and 5) a Fe-Re intermetallic. Potentiostatic and potentiodynamic electrochemical tests were performed using sulfuric acid to evaluate the corrosion resistance of each sample. These tests found that the zirconium rich samples were very corrosion resistant but became increasingly susceptible at higher rhenium concentrations. The iron rich samples were not very resistant to corrosion under the test conditions; there was no notable trend in corrosion behavior related to the introduction of rhenium.

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).

Thesis (Ph.D.)--McMaster University (Canada), 1993. / Source: Dissertation Abstracts International, Volume: 55-06, Section: B, page: 2216. Adviser: R. A. Bell.

Techn. Universiẗat, Diss., 2006--München.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 4, 2007) Vita. Includes bibliographical references.

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