In recent years, people have raised their alertness to the hazard of air pollution. Sulfur dioxide is one of the most dangerous chemical compounds among those air pollutants. A study on removing sulfur dioxide from an air stream by adsorption using wood chips as the adsorbent is presented in this thesis. The reason for using wood as an adsorbent is that wood is a porous material and possesses a large surface of cell cavities which can hold a great amount of moisture. As sulfur dioxide gas is passed through the wood bed, it would be either condensed in the cell space of the wood by intermolecular attraction, adsorption or dissolved in the moisture held in the wood. This work was started with a review of literature. Then related references were collected and a proposal written. Douglas fir was chosen for the experiment because it is the most common kind of wood in the Pacific Northwest. After the process and proper equipment was set up, woodchips were screened and dried to prepare for further experiments. It was decided to use three different concentrations of sulfur dioxide. For each of the concentrations of sulfur dioxide, five levels of moisture (0%', 11%, 20%, 50% and saturated) were assigned to the selected woodchips. Fifteen combinations or experiments were done for the research. The results of the experiments show that dry wood (0% moisture content) had comparatively low characteristics in the adsorption of sulfur dioxide. For instance, at an influent so2 concentration of 1.12 ppm., about· 6 grams of dry woodchips adsorbed 29.37 µg. of sulfur dioxide in comparison to 2Q90.5 µg. of SO2 adsorbed in the same weight of woodchips but saturated with moisture. At an influent SO2 concentration of 1.83 ppm., the adsorption of sulfur dioxide increased from 7.73 µg. for the dry wood to 745.15µg. in the water saturated wood. For an influent SO2 concentration of 4.60ppm., dry wood adsorbed 15.26 µg. of SO2 while the moisture saturated wood adsorbed 1446.2 µg. The amount of dry woodchips used in above mentioned experiments were all about 6 grams. These data show that the moisture saturated wood adsorbed about 90 times the amount of sulfur dioxide that the dry wood adsorbed. It is clear that the wood adsorptivity increased with increasing moisture content. It was also found that wood adsorptivity and retention time were affected by the different flow rate of carrier gas. The figures show that most of the data fit a Freundlich equation. Other equations were developed to calculate the adsorptivity and retention time by obtaining the influent and effluent concentration of sulfur dioxide through the adsorbent bed.

Volcanic eruptions pose hazards to life and insfrastructure, and contribute to the resurfacing of earth and other planetary bodies. Lavas and magmas are multi-phase suspensions of silicate melts (liquids), solid crystals, and vapor bubbles, and solidify into glass and rock upon cooling. The interactions between phases place important controls on the dynamics and timescales of magma and lava transport and emplacement. The purpose of this thesis is to explore the role of multiphase interactions in controlling eruption dynamics and inform conceptual and numerical models for hazard prediction. In Chapters 1 and 2, centimeter to meter scale analog experiments are used to explore the multi-phase rheological properties and flow behaviors of bubble- and particle-bearing suspensions. Optical imaging of dam-break experiments presented in Chapter 1 expand existing experimental parameter ranges for lava analogs to higher bubble concentrations than existing datasets (up to 82% by volume bubbles and 37% by volume particles). I develop a constitutive relationship for threephase relative viscosity, and demonstrate that at the low strain-rate conditions relevant to many natural lava flows, accounting for the rheological effect of bubbles can result in the prediction of slower runout speeds. Chapter 2 expands upon the work of Chapter 1 using different analog materials observed using nuclear magnetic resonance imaging (MRI) phase-contrast velocimetry (PCV) to measure velocity in the flow interior of three-phase dam-break experiments. I find that for high-aspect ratio particles (sesame seeds), phase segregation into shear bands readily occurs, even at low particle fraction (20%) and results in strain localization. I suggest that the presence of shear bands can lead to faster flow runout than predicted using assumptions of bulk rheology. Chapter 3 analyzes thermal infrared (IR) time-lapse photography and videography of Hawaiian to Strombolian explosive activity during the 2021 eruption of Cumbre Vieja volcano, La Palma, Canary Islands, Spain. Images are analyzed to find time series of apparent plume radius, velocity, and apparent volume flux of high-temperature gas and lava. I compare with other measures of eruptive activity, including remote observations of plume height, SO₂ flux, effusive flux, tremor, and events at the volcano edifice including edifice collapses and the opening of new vents. I find correlations between tremor and explosive flux, but no correlation with SO2 flux or effusive flux, which I interpret as evidence of bubble segregation, highlighting the role of phase segregation and temporal variability in material properties in natural systems. Finally, in Chapter 4, I develop a novel finite element model to explore the interaction between a viscous flow with a solidified crust, and the effect of these interactions on lava flow and lava dome emplacement. I develop a model that couples a temperature-dependent viscous interior with an elastic shell flowing into air, water, or dense atmospheres. The model expands upon existing numerical simulations used in volcanology to have direct applications to lava flows and domes on the sea floor, which accounts for a large portion of the volcanism on Earth, and volcanism on other planetary bodies. Additionally, the formation of levees or solidified flow fronts that fracture and lead to a restart of flow. These lava flow breakouts pose a significant hazard, but there are currently no volcanological community codes capable of using a physics-based approach to predict the timing or location of breakouts. The model in Chapter 4 is the first to allow for assessment of the likelihood of failure at the scale of a flow lobe. Chapter 4 describes the model formulation and verification, and validation against centimeter-scale molten basalt experiments. The dissertation as a whole integrates work using a variety of methods including analog experiments, observations of natural eruptions, and numerical simulations to contribute to our understanding of the effects of multi-phase interactions on volcanic eruptions.

Cerium and zirconium oxides are important materials in industrial catalysis. Particularly, the great advances attained in the past 30 years in controlling levels of gaseous pollutants released from internal combustion engines can be attributed to the development of catalysts employing these materials. Unfortunately, oxides of sulfur are known threats to the longevity of many catalytic systems by irreversibly interacting with catalytic materials over some time period. In this work, polycrystalline cerium-zirconium mixed-metal-oxide (MMO) solid solutions of various molar ratios were synthesized. High resolution x-ray photoelectron spectroscopy (XPS) was used to characterize the model system. The spectral data was examined for revelation of the surface species that form on these metal oxides after insitu exposures to sulfur dioxide at various temperatures. The model catalysts were exposed to sulfur dioxide using a custom modified in-situ reaction cell. A reliable sample platen heater was designed and built to allow the exposure of the model system at temperatures up to 673 K. The results of this study demonstrate the formation of sulfate and sulfite adsorbed sulfur species. Temperature and compositional dependencies were displayed, with higher temperatures and ceria molar ratios displaying a larger propensity for forming surface sulfur species. In addition to analysis of sulfur photoemission, the photoemission regions of oxygen, zirconium, and cerium were examined for the materials used in this study before and after the aforementioned treatments with sulfur dioxide. The presence of surface hydroxyl groups was observed and metal oxidation state changes were probed to further enhance the understanding of sulfur dioxide adsorption on the synthesized materials. Palladium loaded mixed-metal oxides were synthesized using a unique solid-state methodology to probe the effect of palladium addition on sulfur dioxide adsorption. Microscopic characterization of the wafers made using palladium-loaded MMO materials provide justification for using this material preparation method in surface science studies. The addition of palladium to this model system is shown to have a strong effect on the magnitude of adsorption for sulfur dioxide on some material/exposure condition combinations. Ceria/zirconia sulfite and sulfate species are identified on the palladium-loaded MMO materials with adsorption sites located on the exposed oxide sites.

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In the early 2000s, hydrogen sulfide (H₂S) was added to the family of molecules known as gasotransmitters, a class of endogenously produced and freely diffusing biological signaling molecules. Since this discovery, biologists and chemists have sought to understand the physiological roles of H₂S and to elucidate the potential benefits of exogenous H₂S delivery. As a result, many synthetic small molecule donor compounds have been created to deliver H₂S in response to various biologically relevant stimuli. Furthermore, macromolecular and supramolecular H₂S donor systems have been created to protect donors in the biological milieu, extend release kinetics, or control H₂S release conditions. Thus, H₂S-donating nanostructures with precisely tuned release rates provide invaluable tools for further investigating the biological roles and therapeutic potential of H₂S. This work describes two polymer micelle systems for the controlled delivery of H₂S. The first system is based on H2S-releasing polymer amphiphiles with varying degrees of a plasticizing comonomer incorporated into the core-forming block. The glass transition temperature of the core-forming block varied predictably with incorporation of the plasticizing comonomer. Accordingly, the half-life of H₂S release decreased from 4.2 h to 0.18 h with increasing core-forming block mobility. The second system is based on H₂S releasing polymer amphiphiles with varying degrees of crosslinking in the core-forming block. The crosslinked system was designed to achieve control over H₂S release rate with minimal dilution of donor in the core-forming block. The half-life of H₂S release increased from 117 min to 210 min with increasing crosslink density in the core-forming block, further demonstrating that H₂S release rates can be precisely controlled by tuning micelle core mobility. Beyond control over H₂S release rate, further study of the biological roles of H₂S requires donor systems with precisely triggered release. To this end, this dissertation also discusses efforts to investigate fundamental micelle–unimer relationships. This section includes an evaluation of the impact of core-forming block mobility on micelle–unimer coexistence utilizing a model polymer amphiphile system. Unimer populations correlated with glass transition temperatures of the core-forming block, suggesting the need to consider micelle core mobility when discussing polymer chain phase behavior of amphiphilic block copolymers. Finally, this work discloses new methods for the radical polymerization of poly(olefin sulfones) with control over molecular weight. POSs are a unique class of polymers with great potential for stimuli-responsive depolymerization to generate sulfur dioxide (SO₂), a signaling gas related to H₂S. / Doctor of Philosophy / Hydrogen sulfide (H2S) is commonly known for its pungent odor and toxicity. Despite this negative stigma, H2S has been revealed as a vital signaling molecule in both plants and animals. This discovery has prompted the coordination of biologists and chemists in an effort to better understand the roles of H2S in the body. Driven by this motive, great interest has centered around the development of finely tuned molecules designed to generate H2S in the body, termed H2S donors. A variety of synthetic H2S donors have been reported with various conditions enabling release. Building on this work, the development of polymeric H2S donors with tunable release rates will enable investigation into the complex behavior of H2S in the body. The first half of this dissertation focuses on the design and synthesis of two polymeric H2S donor systems for the controlled release of H2S. These systems take advantage of sequestering the H2S donating species inside a polymeric nanostructure in water called a micelle. Because H2S release requires a triggering molecule to enter the polymeric nanostructure, release rate can be tuned by modifying the mobility of the structure. The first system discussed demonstrates this concept by increasing the flexibility of the micelle core. As expected, H2S release rates increased with increasing flexibility. The second system discussed advances this idea by limiting mobility within the micelle core, rather than increasing flexibility. Accordingly, H2S release rates decreased with decreasing mobility within the micelle core. The latter half of this dissertation broadly explores the development of polymeric signaling gas delivery vehicles with triggered release conditions. We first investigate the impact of polymer chain flexibility on the formation of micelles in water. Polymer chain flexibility significantly impacted the balance between micelles and unassembled polymer chains in solution, suggesting the need to consider this characteristic when designing donor systems for precise release conditions. Lastly, we discuss the development of controlled polymerization techniques for poly(olefin sulfones). We envision that poly(olefin sulfones) will be a useful class of polymers in the design of donor systems relying on triggered depolymerization for release of the signaling gas sulfur dioxide.

Title IV of the 1990 Clean Air Act Amendments established a market-based incentive approach to pollution control through the use of tradable allowances for sulfur dioxide (SO₂) emissions by electric utilities. Many researchers have theorized that this approach will be compromised by state regulatory policies that create incentives for utilities to invest in costly pollution control equipment, inhibiting the formation of a free and competitive allowance market. The pUrpose of this research is to investigate the impact of state regulatory policies on the development of the SO₂ allowance market. More specifically, this research examines whether the geographic distribution of traded SO₂ allowances (as determined by an analysis of EPA Allowance Tracking System data) has been affected by the actions of state regulators. The research also investigates the effect of Title IV on the Virginia coal industry. Several trends in the allowance market are identified in this study, including the declining price of allowances, over compliance at Phase I units, and the geographic patterns of trading. This research only partially supports earlier predictions that states with regulatory policies biased towards costly capital investments in flue gas desulfurization (scrubber) retrofits would become net allowance sellers in the national market. However, the research finds that these state policies, along with several other factors (including the Phase I Extension program, the tax treatment of allowances, and the risk-averse nature of utilities) have contributed to the slow growth in the allowance market. The research also concludes that Virginia low-sulfur coal producers are not benefiting from Title IV implementation. / Master of Urban and Regional Planning