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Environmental and energy issues have stimulated renewed interest in utilizing both water and methanol as reagents and reaction mediums. Our current interest is to evaluate the scope of group nine organometallics and establish thermodynamic parameters for their reactivity in aqueous solvent. A comprehensive thermodynamic database for a wide scope of organo-rhodium transformations in a range of reaction media including benzene, water, and methanol has been well established by our group. Aqueous solutions of rhodium porphyrin have been determined to manifest an exceptional range of substrate reactions with carbon monoxide, dihydrogen, olefins, methanol and aldehydes. This study will focus on expansion of the thermodynamic database to all the group nine metals, particularly the iridium porphyrin systems in both water and methanol. Substrate reactivity and development of new mechanistic strategies for the conversion of carbon monoxide, alkanes, and alkenes to organic oxygenates are central objectives. Water/Methanol soluble porphyrin iridium complexes including iridium tetrakis(p-sulfonatophenyl)porphyrin ((TSPP)Ir) and iridium tetrakis(3,5-sulfonatomesityl)porphyrin ((TMPS)Ir) derivatives can be prepared by sulfonation of tetra phenyl porphyrin (H2TPP) and tetra mesityl porphyrin (H2TMP). The reactivity of dihydrogen with aqueous solutions of iridium(III) tetrakis(p-sulfonatophenyl)porphyrin ((TSPP)Ir(III)) complexes produce equilibrium distributions between six iridium species including iridium hydride ([(TSPP)Ir-D(D2O)]-4), iridium(I) ([(TSPP)IrI(D2O)]-5), and iridium (II) dimer ([(TSPP)IrII(D2O)]2-8) complexes. Each of these types of iridium porphyrin species including Ir(I), Ir(II), Ir(III), Ir-H, and Ir-OH function as precursors for a range of organometallic substrate reactions. A primary objective is to define the quantitative relationships pertaining to the distribution of species in aqueous solution as a function of the dihydrogen and hydrogen ion concentrations through direct measurement of five equilibrium constants along with free energy changes of coordinated water and free energy changes of reactions of dihydrogen in water. Reactivity, kinetics and evaluation of equilibrium thermodynamics, including the reactions of iridium hydroxide and methoxide with olefins to produce beta-hydroxyalkyl and beta-methoxyalkyl complexes, reactions of iridium hydride and olefins to produce iridium alkyl complexes, and reactions of iridium hydride with carbon monoxide to produce iridium formyl [Ir-CHO] complexes are also objectives of this research. Another research goal is the design and synthesis of diporphyrin ligands that form dimetal complexes capable of preorganizing transition states for substrate reactions that involve two metal centers. Dirhodium dimetalloradical complexes are observed to manifest large rate increases over mono-metalloradical activation reactions of hydrogen, methane, and other small molecule substrates. In this study, synthesis of diporphyrin (bisporphyrin) ligands and other ligands which will permit dimetallo complexes like anti-aromatic [14]annulene and low steric porphine ligands will be also be examined. / Chemistry

Transport properties of novel sulfonated wholly aromatic copolymers and the state-of-the-art poly(perfluorosulfonic acid) copolymer membrane for fuel cells, Nafion, were compared. Species transport (protons, methanol, water) in hydrated membranes was found to correspond with the water-self diffusion coefficient as measured by pulsed field gradient nuclear magnetic resonance (PFG NMR), which was used as a measure of the state of absorbed water in the membrane. Generally, transport properties decreased in the order Nafion > sulfonated poly(arylene ether sulfone) > sulfonated poly(imide). The water diffusion coefficients as measured by PFG NMR decreased in a similar fashion indicating that more tightly bound water existed in the sulfonated poly(arylene ether sulfone) (BPSH) and sulfonated poly(imide) (sPI) copolymers than in Nafion. Electro-osmotic drag coefficient (ED number of water molecules conducted through the membrane per proton) studies confirmed that the water in sulfonated wholly aromatic systems is more tightly bound within the copolymer morphology. Nafion, with a water uptake of 19 wt % (λ = 12, where λ = N H2O/SO3H) had an electro-osmotic drag coefficient of 3.6 at 60°C, while BPSH 35 had an electro-osmotic drag coefficient of 1.2 and a water uptake of 40 wt % (λ = 15) under the same conditions. Addition of phosphotungstic acid decreased the total amount of water uptake in BPSH/inorganic composite membranes, but increased the fraction of loosely bound water. Zirconium hydrogen phosphate/BPSH hybrids also showed decreased bulk water uptake, but contrary to the results with phosphotungstic acid, the fraction of loosely bound water was decreased. This dissimilar behavior is attributed to the interaction of phosphotungstic acid with the sulfonic acid groups of the copolymer thereby creating loosely bound water. No such interaction exists in the zirconium hydrogen phosphate materials. The transport properties in these materials were found to correspond with the water-self diffusion coefficients. Proton exchange membrane (PEM) transport properties were also found to be a function of the molecular weight of sulfonated poly(arylene thioether sulfone) (PATS). Low molecular weight (IV ~ 0.69) copolymers absorbed more water on the same ion exchange capacity basis than the high molecular weight copolymers (IV ~ 1.16). Surprisingly, protonic conductivity of the two series was similar. Moreover, the methanol permeability of the low molecular weight copolymers was increased, resulting in lower membrane selectivity and decreased mechanical properties. The feasibility of converting the novel sulfonated wholly aromatic systems to membrane electrode assemblies (MEAs) for use in fuel cells was studied by comparing free-standing membrane properties to those of MEAs assembled with standard Nafion electrodes. Significantly higher interfacial resistance was measured for BPSH samples. Fluorine was introduced into the copolymer backbone by utilizing bisphenol-AF in the copolymer synthesis (6F copolymers). These 6F copolymers showed a markedly lower interfacial resistance with Nafion electrodes and correspondingly greater direct methanol fuel cell performance. It was proposed that the addition of the hexafluoro groups increased the compatibility of the PEM with the highly fluorinated Nafion electrode. / Ph. D.

The targeted design of new catalyst materials can only be accomplished once a fundamental understanding of the interactions between material surfaces and adsorbed molecules is developed. In situ infrared spectroscopy and mass spectrometry methods were employed to probe interactions at the gas-surface interface of oxide-supported metal nanoparticle materials. High vacuum conditions allowed for systematic investigations to describe detailed reaction mechanisms. Specifically, variable temperature infrared spectroscopy was utilized to uncover the binding energetics of CO to the oxide surface of TiO2-based materials. As binding energetics are related to the electronic structure of the adsorption site, differences in evaluated binding enthalpies are hypothesized to probe electronic metal-support interactions that describe charge transfer between the supported metal nanoparticles and TiO2. Cu/TiO2 aerogels were identified as a candidate for more in-depth studies. Flow reactor methods in combination with the surface-based infrared spectroscopy were utilized to elucidate the CO oxidation reaction mechanism over Cu/TiO2 aerogels. Bridging oxygen atoms on TiO2 regions of the material were identified as the active site for catalysis in a Cu-assisted Mars-van Krevelen lattice extraction mechanism. Methanol oxidation was then studied with similar methods to show the complete conversion to CO2 and H2O at high temperatures through the reduction of titania and formation of a formate intermediate. Higher-order carbonaceous alcohols were probed for adsorption and reactivity on Cu/TiO2 aerogels and were observed to follow a similar reaction pathway. The higher-order alcohols, however, were shown to undergo a partial oxidation pathway in the absence of gaseous O2 that is hypothesized to originate from enhanced binding to Cu sites. The decomposition of the chemical warfare agent simulant dimethyl chlorophosphate was also investigated. A hydrolysis pathway to form the significantly less toxic molecule CH3Cl was observed, highlighting the unique promotional effects and chemistry on Cu/TiO2 aerogels. The results presented exemplify both the influence of electronic metal-support interactions on catalysis and the versatile reactivity of Cu/TiO2 aerogels. / Doctor of Philosophy / Interactions between small gaseous molecules and material surfaces have very important implications for applications regarding the environment, industry, and military/public safety. The mechanisms in which gases interact with a solid surface can determine how the material can be functionally used as catalysts. Scientists and engineers start to build a fundamental understanding of what makes a catalyst successful for different applications by understanding the location and strength of interactions. A catalyst's surface acts to lower activation barriers and provide low-energy pathways for interacting molecules to chemically change, by breaking bonds for molecular decomposition and/or forming new bonds. The vibrations of chemical bonds that break and form on surfaces are probed with infrared spectroscopy at the gas-surface interface to study molecular adsorption and reactivity. In addition, a flow cell reactor is used to characterize reaction progress and identify products in real-time. A class of reactive nanoparticulate materials is utilized as a model system on which to study various chemical reactions for important applications including small molecule oxidation for industrial detoxification and clean energy applications, as well as the decomposition of chemical warfare agents. Reaction mechanisms for the oxidation of carbon monoxide and alcohols were elucidated through the utilization of the methods described above. In addition, the decomposition of a chemical warfare agent simulant is characterized. The discoveries and understanding of important chemical properties presented in this dissertation will aid in the synthesis of effective next-generation catalyst materials.

The increased use of alcohols as gasoline additives, and possible substitutes, has prompted the investigation of the fate of gasoline/alcohol mixtures in the environment. In situ bioremediation is one technique that can successfully be applied to remove ground water contaminants particularly in situations where the adsorptive capacity of the soil plays a major role. Frequently, enhanced in situ bioremediation techniques rely on indigenous microorganisms to degrade ground water contaminants; this technique may sometimes include the addition of acclimated bacteria. In this study, soil microcosms were constructed in order to simulate the conditions found in a saturated aerobic aquifer. The biodegradation potential of methanol, benzene, and m-xylene was investigated. Uncontaminated soil from the surface, 12, 16.5, and 18 foot depths was utilized to observe the differences in microbial responses throughout the soil profile. The biodegradation potential of the indigenous microbiota was determined and compared to that of benzene acclimated bacteria, for all the compounds in the mixture. To observe the impact that chemical and physical soil characteristics may have on microbial responses, soils from each depth were classified on the basis of their particle size, moisture content and pH. Substantial methanol, benzene, and m-xylene biodegradation by the indigenous microorganisms occurred in all subsurface soils. While methanol was readily biodegradable over concentrations ranging from about 80 mg/L to about 200 mg/L, benzene inhibited methanol biodegradation at about 125 mg/L in all soil depths. The addition of benzene acclimated bacteria considerably increased the biodegradation rates of all compounds in the mixture. Such increases in biodegradation rates may be attributed to the activities of both groups, the indigenous microorganisms and the benzene acclimated bacteria. The results obtained by this study suggest that biodegradation of methanol, benzene, and m-xylene can readily occur in a saturated aerobic subsurface environment. The physical and chemical properties of a ground water aquifer seem to have a marked effect on microbial responses, and consequently on the biodegradation potential of water contaminants. / Master of Science

Partial denitrification/anammox (PdNA) is a biological nitrogen removal technology with significant carbon and aeration savings when compared with conventional nitrification/denitrification. Yet despite these benefits, the use of PdNA in mainstream wastewater treatment remains limited. One of the main barriers to implementation of anammox-based technologies is the slow growth rate of anammox (AMX), which results in a long startup time. To accelerate startup, the typical approach to commissioning AMX-based processes, specifically used for sidestream partial nitritation/AMX, is with biomass augmentation, which is practically unrealistic for full-scale mainstream applications. Thus, this study evaluated startup strategies for mainstream PdNA without AMX inoculation in moving bed biofilm reactors (MBBRs) with two simultaneous experiments. In one experiment, an MBBR was started using IFAS carriers with a preliminary biofilm and no external carbon dosing or AMX biomass inoculation. The feed was controlled to 20°C and included mainstream conditions of nitrite and ammonia controlled to the stoichiometric requirements for AMX growth. After only 84 days of operation, AMX activity was confirmed in the reactor with evidence of activity a few weeks before testing. In the second experiment, four reactors were started with either virgin carriers or integrated fixed-film activated sludge (IFAS) carriers with a preliminary biofilm of heterotrophs and nitrifiers. The reactors were fed mainstream levels of ammonia and nitrate with a temperature control target of 20°C and one reactor of each carrier type was dosed with carbon in the form of either glycerol or methanol. Carbon dosing was based on a feedback proportional-integrative-derivative (PID) control loop with a nitrate residual of 1-1.5 mgNO3-N/L. Of the four reactors, the preliminary biofilm carrier reactor dosed with glycerol achieved AMX activity first after 224 days of operation, but it was determined this was likely limited by synthetic feeding for the first 184 days. These results, along with other recent PdNA work, suggest that growth of AMX on biofilm carriers can be established in mainstream conditions in 50-100 days, depending on media selection and carbon source. Ultimately, this research will help utilities understand methods for starting up mainstream PdNA MBBRs from scratch and make this technology more accessible. / Master of Science / Intensification is the practice by which operational changes and new technologies are employed to reduce economic, resource, energy, and space requirements of wastewater treatment plants. One area of increasing focus involves the use of anaerobic ammonia oxidizing bacteria, or anammox (AMX), to reduce the aeration and carbon dosing needs for treating wastewater. One of the main barriers to implementation of AMX-based technologies is the slow growth rate of AMX, which results in a long startup time. To accelerate startup, the typical approach to commissioning AMX-based processes, specifically used for sidestream partial-nitritation/AMX, is with augmentation of biomass, which is practically unrealistic for full-scale mainstream applications. Thus, this study evaluated startup strategies for mainstream moving bed biofilm reactors (MBBRs) without AMX biomass inoculation in two simultaneous experiments in an AMX MBBR and a partial denitrification/AMX (PdNA) MBBR. In one experiment, idealized stoichiometric conditions for AMX growth were provided to a mainstream MBBR started with carriers from an aerobic integrated fixed-film activated sludge (IFAS) process to determine how fast AMX could potentially grow. In another experiment, different carrier types, virgin or preliminary biofilm carriers from an IFAS process, and different carbon sources, methanol and glycerol, were tested to determine the best methods for encouraging AMX attachment and growth in a PdNA process. These results, along with other recent PdNA work, suggest that growth of AMX on biofilm carriers can be established in mainstream conditions within 50-100 days, depending on media selection and carbon source. Ultimately, this research will help utilities understand methods for starting up mainstream PdNA MBBRs from scratch and make this technology more accessible.

Yes / In this study, a Fuzzy Bayesian network (FBN) approach was proposed to analyze the domino effects of pool fire in storage tanks. Failure probabilities were calculated using triangular fuzzy numbers, the combined Center of area (CoA)/Sum-Product method, and the BN approach. Consequence modeling, probit equations, and Leaky-Noisy OR (L-NOR) gates were used to analyze the domino effects, and modify conditional probability tables (CPTs). Methanol storage tanks were selected to confirm the practical feasibility of the suggested method. Then the domino probability using bow-tie analysis (BTA), and FBN in the first and second levels was compared, and the Ratio of Variation (RoV) was used for sensitivity analysis. The probability of the domino effect in the first and second levels (FBN) was 0.0071472631 and 0.0090630640, respectively. The results confirm that this method is a suitable tool for analyzing the domino effects and using FBN and L-NOR gate is a good way for assessing the reliability of tanks. / National Petrochemical Company (NPC) of Iran