In this work, electrolytes for secondary batteries and fuel cells were investigated. Ionic liquids (ILs), for use as battery electrolytes, were formed using quaternary ammonium salts (Quats) and aluminum chloride. The room temperature (RT) carbonate fuel cell was demonstrated by modifying a commercially available anion exchange membrane, utilizing positive quaternary ammonium fixed sites, to transport carbonate. The charge density on the nitrogen and the symmetry of the Quat were demonstrated to be the dominant factors in determining the IL melting point (MP). The introduction of a benzyl ring was found to lower the MP of the ILs by increasing the size of the Quat, while disrupting its symmetry. ILs formed from asymmetric quaternary ammonium salts having three distinct groups were found to have lower melting points than those formed using Quats with two groups. Replacement of an alkyl group with a rigid ether linkage can lower the IL melting point. Assymetric alkyl substituted Quats were found to form more electrochemically stable, less viscous ILs than their benzyl substituted counterparts. The increased electrochemical stability is due to the smaller butyl chain being a worse leaving group than the benzyl group. Similarly, the smaller size of the alkyl substituted Quats results in the lower viscosities. Lithium and sodium can be reversibly deposited from neutral ILs following the addition of an additive (such as SOCl2). The additive disrupts the strong coordination between Na+, or Li+, and AlCl4-. Chlorinated compounds, such as chloroform-D and carbon tetrachloride, were demonstrated to catalyze the reversible reduction of sodium. When neutralized with lithium and sodium, reversible Li-Na alloys were deposited. The Li-Na alloy appears to suppress dendrite formation and could potentially be used as a metal based anode in a rechargeable Li battery. A novel room temperature carbonate fuel cell was constructed. The alkaline environment could eliminate the need for water in the oxidation of methanol. Cells were operated on hydrogen, 1M methanol, and pure methanol fuels. CO2 was produced at the anode and O2 and CO2 were necessary at the cathode for operation, indicating that carbonate was the conducting ion.

This work showcases the utility of switchable materials. Included are a switchable room-temperature ionic liquid, a switchable solvent, a switchable heterogeneous catalyst system, and a switchable gel. First, the switchable ionic liquid 2-butyl-1,1,3,3-tetramethylguanidium methylcarbonate is fully investigated. Its use in a complete chemical process (including reaction, separation, reformation, and recycle) is demonstrated with several reactions. Furthermore, its potential use for bitumen separation and purification and SO2 capture/isolation are discussed, and preliminary data is presented. Next, piperylene sulfone (PS), a switchable solvent, is synthesized and fully characterized. Anionic nucleophilic substitution reactions were performed in PS, the products were isolated in high yields, and then the PS was reformed for reuse. Then, we designed an immobilized fluorous microphase system that uses F-MonoPhos to induce high enantioselectivities as a switchable heterogeneous catalyst system. Finally, stable reversible polyethyleimine-CO2 gels have been synthesized with 1-octanol. Our findings indicate that PEI-1200/octanol/CO2 gels have potential as a possible drug carrier matrix for transdermal delivery applications.

Groundwater at many existing and former industrial sites and disposal areas is contaminated by halogenated organic compounds that were released into the environment. The chlorinated solvent trichloroethylene (TCE) is one of the most ubiquitous of these compounds. In situ chemical oxidation (ISCO) has been successfully used for the removal of TCE. The objective of this study was to apply the ISCO technology to remediate TCE-contaminated groundwater. In this study, potassium permanganate (KMnO4) was used as the oxidant during the ISCO process. The study consisted bench-scale and pilot-scale experiments. In the laboratory experiments, the major controlling factors included oxidant concentrations, effects of soil oxidant demand (SOD) on oxidation efficiency, and addition of dibasic sodium phosphate on the inhibition of production of manganese dioxide (MnO2). Results show that higher molar ratios of KMnO4 to TCE corresponded with higher TCE oxidation rate under the same initial TCE concentration condition. Moreover, higher TCE concentration corresponded with higher TCE oxidation rate under the same molar ratios of KMnO4 to TCE condition. Results reveal that KMnO4 is a more stable and dispersive oxidant, which is able to disperse into the soil materials and react with organic contaminants effectively. Significant amount of MnO2 production can be effectively inhibited with the addition of Na2HPO4. Results show that the increase in the first-order decay rate was observed when the oxidant concentration was increased, and the half-life was approximately 24.3 to 251 min. However, the opposite situation was observed when the second-order decay rate was used to describe the reaction. Results from the column experiment show that the breakthrough volumes were approximately 50.4 to 5.06 pore volume (PV). Injection of KMnO4 would cause the decrease in TCE concentration through oxidation. Results also indicate that the addition of Na2HPO4 would not inhibit the TCE removal rate. In the second part of this study, a TCE-contaminated site was selected for the conduction of pilot-scale study. A total of eight remediation wells were installed for this pilot-scale study. The initial TCE concentrations of the eight wells were as follows: C1 = 0.59 mg/L, C1-E = 0.64 mg/L, C1-W = 0.61 mg/L, EW-1 = 0.65 mg/L, EW-1E = 0.62 mg/L, EW-1W = 0.57 mg/L, C2 = 0.62 mg/L, C3 = 0.35 mg/L. C1, EW-1, C2, and C3 were located along the groundwater flow direction from the upgradient (C1) to the downgradient location (C3), and the distance between each well was 3 m. C1-E and C1-W were located in lateral to C1 with a distance of 3 m to C1. EW-1E and EW-1W were in lateral to EW-1 with a distance of 3 m to EW-1. In the first test, 2,700 L of KMnO4 solution was injected into each of the three injection wells (C1, C1-E, and C1-W) with concentration of 5,000 mg/L. Three injections were performed with an interval of 6 hr between each injection. After injection, the TCE concentrations in those three wells dropped down to below detection limit (<0.0025 mg/L). However, no significant variations in TCE concentrations were observed in other wells. In the second test, 2,700 L of KMnO4 solution was injected into injection well (EW-1) with concentration of 5,000 mg/L. Six injections were performed with an interval of 6 hr between each injection. After injection, the TCE concentrations in the injection well dropped down to below detection limit (<0.0025 mg/L). TCE concentrations in (C1, C1-E, C1-W, EW-1E, EW-1W, C2, and C3) dropped to 0.35-0.49 mg/L. After injection, no significant temperature and pH variation was observed. However, increase in conductivity and oxidation-reduction potential (ORP) was observed. This indicates that the KMnO4 oxidation process is a potential method for TCE-contaminate site remediation. The groundwater conductivity increased from 500 £gS/cm to 1,000 £gS/cm, and ORP increased from 200 to 600 mv. Increase in KMnO4, MnO2, and total Mn was also observed in wells. Results from the slug tests show that the hydraulic conductivity remained in the range from 10-4 to 10-5 m/sec before and after the KMnO4 injection.

We develop, characterize, and apply novel solvent systems for enhanced separations. The field of separations has long been explored by chemical engineers. One way to optimize separations is through solvent manipulation. Through molecular design, smart solvents can be created which accomplish this task. Smart solvents undergo step or gradual changes in properties when activated by a stimulus. These property changes enable unique chemistry and separations. This thesis explores the application of two different types of smart solvents: switchable and tunable solvents. First we show that a neutral liquid can react with carbon dioxide and be switched into an ionic liquid which can then be thermally reversed back to its molecular form. Each form that the solvent takes has unique properties that can be structurally tuned to span a large range. We also look at a tunable solvent system based on polyethylene glycol/dioxane that is initially homogeneous, but induced to a heterogeneous system through carbon dioxide pressurization. Finally, we look at the advantage of using carbon dioxide as a co-solvent that is easily removed post-reaction for the grafting of silanes onto polyolefin backbones.

Study of turbulent flow over a rough bed is highly important due to its numerous applications in the areas of sediment transport and pollutant discharge in streams, rivers and channels. Over the past few decades, many experimental studies have been conducted in this respect to understand the underlying phenomenon. However, there is a scarcity in the number of computational studies conducted on this topic. Therefore, a Large Eddy Simulation (LES) of turbulent flow over a rough channel bed was conducted to contribute further understanding of the influence of bed roughness on turbulent flow properties. For this purpose, an efficient, second order accurate 'immersed boundary method' was implemented into the LES code Hydro3d-GT, and validated for flow past bluff bodies. LES results from the present study showed excellent agreement with previous experimental studies on flow over rough beds. An in-depth analysis of time varying turbulent quantities (like the velocity fluctuations) revealed the presence of coherent structures in the flow. Also, a three dimensional visualization of the turbulent structures provided a good picture of the flow, especially in the near bed region, which is quite difficult to accomplish using experimental studies.

Novel solvents utilizing a reversible CO₂ induced property switch are presented. The synthetic procedure for designing the solvents is discussed, along with detailed characterizations on both solvent forms to serve as a tool for optimal solvent identification as well as future solvent design. A reflectance infrared spectroscopic technique is introduced to allow for the examination of CO₂ and solvent composition under high pressures and temperatures. The magnitude of solvent property changes afforded by this "switch" creates opportunities for sustainable processing; discussed are the application to coupling reactions and separations, and CO₂ capture. The switchable solvents are shown to serve as effective media for running reactions, with the switch providing facile recovery of products and catalysts for solvent recycling. Lastly, the switch itself is exploited to provide for the separation of CO₂ from low partial pressure feed streams, and structure-property relationships were successfully used to develop next generation materials with enhanced absorption capacities. The viscosity of the solvents, as a function of temperature and composition, is also presented.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Bibliography: leaves 187-190.

The thermal degradation of polyvinyl chloride (PVC) is a significant processing challenge which can lead to deleterious mechanical and optical properties in a wide range of products. Synergetic studies on PVC model compounds and blends of bulk PVC provide unique insights into the thermal degradation and stabilization pathways in the presence of common additives. Model PVC compounds were selected to replicate specific defects (e.g., allylic, vicinal and tertiary) and tacticity (i.e., utilizing stereochemistry to investigate tacticity) commonly found in PVC. Model studies were conducted neat (solvent-free) with metal carboxylates. Experimental results highlight that the allylic and tertiary defects are more reactive than pristine PVC and isotactic sites are more reactive than their syndiotactic counterparts. Zinc stearate was found to act not in the role of substituent, but as a Lewis acid by facilitating dehydrochlorination of labile chlorides. This prevents the accumulation of hydrogen chloride and autocatalytic chain unzipping. In contrast, calcium stearate delayed the formation of zinc chloride, a much stronger Lewis acid than zinc stearate, through an ion exchange process to form calcium chloride. Thermal weight loss studies using blends of bulk PVC proved critical in transferring mechanistic insights into the context of a polymeric matrix. Post-combustion carbon capture has traditionally involved the use of aqueous alkanol amine solutions. The regeneration of such systems, however, can be costly and energy intensive. We have developed an alternative system utilizing silylated alkylamines to reversibly capture CO2 under near ambient conditions. The silyl amines developed capture CO2 through chemical reaction to form reversible ionic liquids (RevIL). RevILs utilize no added water and are tunable by molecular design allowing us to influence industrially relevant carbon capture properties such as viscosity, temperature of reversal, and enthalpy of regeneration, while maximizing overall CO2 capture capacity. We demonstrate a strong structure-property relationship among the silyl amines where minor structural modifications lead to significant changes in the bulk properties of the RevIL. Amine containing substrates are important building blocks for a variety of biological and pharmaceutical compounds. However, application of the otherwise versatile Suzuki reaction to these substrates has proved challenging due to either ligation of the amine to the palladium or to electronic effects slowing the oxidative addition step. Conventional methods to overcome these challenges involve protection-deprotection strategies or the use of designer ligands to facilitate reaction. We have shown that application of CO2 pressure and adjusting the water content of the reaction system facilitate the Suzuki coupling of 4-amino-2-halopyridines in high yield with the simple Pd(TPP)2Cl2 catalyst. The protocol was expanded to 2-halopyridines. The results of these investigations will be discussed.

In this thesis we study the effect of electron-electron interactions on Chiral two-dimensional electron gas (C2DEGs). C2DEGs are a very good description of the low-energy electronic properties of single layer and multilayer graphene systems. The low-energy properties of single layer and multilayer graphene are described by Chiral Hamiltoninans whose band eigenstates have definite chirality. In this thesis we focus on the effect of electron-electron interactions on two of these systems: monolayer and bilayer graphene. In the first half of this thesis we use the massless Dirac Fermion model and random-phase-approximation to study the effect of interactions in graphene sheets. The interplay of graphene's single particle chiral eigenstates along with electron-electron interactions lead to a peculiar supression of spin susceptibility and compressibility, and also to an unusual velocity renormalization. We also report on a theoretical study of the influence of electron-electron interactions on ARPES spectra in graphene. We find that level repulsion between quasiparticle and plasmaron resonances gives rise to a gap-like feature near the Dirac point. In the second half we anticipate interaction driven integer quantum Hall effects in bilayer graphene because of the near-degeneracy of the eight Landau levels which appear near the neutral system Fermi level. We predict that an intra-Landau-level cyclotron resonance signal will appear at some odd-integer filling factors, accompanied by collective modes which are nearly gapless and have approximate q[superscrit 3/2] dispersion. We speculate on the possibility of unusual localization physics associated with these modes. / text

Methane hydrates are naturally-occurring ice-like substances found in permafrost and in ocean sediments along continental shelves. These compounds are often the source of cold seeps—plumes which vent methane into aquatic environments, and may subsequently release the potent greenhouse gas into the atmosphere. Methane hydrates and methane gas seeps are of particular interest both for their potential as an energy source and for their possible contribution to climate change. In an effort to improve location of hydrates through the use of seismic surveys and echo-sounding technology, this work aims to describe the low-frequency (10 Hz to 10 kHz) acoustic behavior of methane gas bubbles and methane hydrates in water under simulated ocean-floor conditions of low temperatures and high pressures. Products of the experiments and analysis presented in this thesis include (a) passive acoustic techniques for measurement of gas flux from underwater seeps, (b) a modified form of Wood's model of low-frequency sound propagation through a bubbly liquid containing real gas, and (c) low-frequency measurements of bulk moduli and dissociation pressures of four natural samples of methane hydrates. Experimental procedures and results are presented, along with analytical and numerical models which support the findings. / text