Browsing by Author "Dandy, David, committee member"
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Item Open Access Application of alcohols in spark ignition engines(Colorado State University. Libraries, 2018) Aghahossein Shirazi, Saeid, author; Reardon, Kenneth, advisor; Foust, Thomas, committee member; Dandy, David, committee member; Marchese, Anthony, committee member; Windom, Bret, committee memberReplacing petroleum fuels with sustainable biofuels is a viable option for mitigation of climate change. Alcohols are the most common biofuels worldwide and can be produced biologically from sugary, starchy and lignocellulosic biomass feedstocks. Alcohols are particularly attractive options as fuels for spark ignition engines due to the high octane values of these molecules and their positive influence on performance and emissions. In the context of the US Department of Energy's Co-Optimization of Fuels and Engines (Co-Optima) initiative, a systematic product design methodology was developed to identify alcohols that might be suitable for blending with gasoline for use in spark ignition engines. A detailed database of 943 molecules was established including all possible molecular structures of saturated linear, branched, and cyclic alcohols (C1-C10) with one hydroxyl group. An initial decision framework for removing problematic compounds was devised and applied. Next, the database and decision framework were used to evaluate alcohols suitable for blending in gasoline for spark ignition engines. Three scenarios were considered: (a) low-range (less than 15 vol%) blends with minimal constraints; (b) ideal low-range blends; and (c) high-range (greater than 40 vol%) blends. A dual-alcohol blending approach has been tested. In addition, the azeotropic volatility behavior and mixing/sooting potential of the single and dual-alcohol gasoline blends were studied by monitoring the distillation composition evolution and coupling this with results of a droplet evaporation model. Although nearly all of the work done on alcohol-gasoline blends has been on single-alcohol blends, the results of this study suggest that dual-alcohol blends can overcome many of the limitations of single-alcohol blends to provide a broader spectrum of advantaged properties. A third study focused on the possibility of replacing anhydrous ethanol fuel with hydrous ethanol at the azeotrope composition, which can result in significant energy and cost savings during production. In this collaborative study, the thermophysical properties and evaporation dynamics of a range of hydrous and anhydrous ethanol blends with gasoline were characterized. The results showed that hydrous ethanol blends have the potential to be used in current internal combustion engines as a drop-in fuel with few or no modifications.Item Open Access Deactivation of ZSM-5 during catalytic fast pyrolysis of biomass(Colorado State University. Libraries, 2018) Stanton, Alexander R., author; Reardon, Kenneth, advisor; Iisa, Kristiina, advisor; Dandy, David, committee member; Marchese, Anthony, committee member; Smith, Gordon, committee memberTo view the abstract, please see the full text of the document.Item Open Access Design, construction and commissioning of an organic Rankine cycle waste heat recovery system with a Tesla-hybrid turbine expander(Colorado State University. Libraries, 2011) Cirincione, Nicholas, author; Olsen, Daniel, advisor; Zimmerle, Daniel, committee member; Dandy, David, committee memberIssues surrounding energy are some of the most compelling subjects in the world today. With human's ever increasing need for energy, production must increase or consumption must be reduced to avoid an unsustainable long-term energy balance. One part of the energy solution is low-temperature Organic Rankine Cycles (ORCs). ORCs can be utilized to produce power in mass quantity from a dedicated heat source such as a geothermal well. ORCs may also be utilized as a waste heat recovery system to generate power from a heat stream that is typically rejected to the environment. Low-temperature waste heat streams are ubiquitous as every internal combustion engine generates 55-75% of its total fuel energy as waste heat. Efficiency of a waste heat recovery ORC system is strongly dependent on condensing temperature and expander efficiency. Condensing temperatures are typically kept low with an evaporative condensing unit. However, water consumption to increase energy production is becoming less tolerated. To provide a means to conduct research around these issues, a waste heat recovery ORC test bed was designed and constructed. This thesis contains information on construction and operation of the test bed with these features: R245fa working fluid, direct dry cooled condensing and a Tesla-hybrid turbine expander.Item Open Access Development of paper-based analytical devices for particulate metals in welding fume(Colorado State University. Libraries, 2015) Cate, David M., author; Henry, Charles S., advisor; Volckens, John, advisor; Dandy, David, committee member; Peel, Jennifer, committee member; Lear, Kevin, committee memberExposure to metal-containing particulate matter places a tremendous burden on human health. Studies show that exposures lead to cardiovascular disease, asthma, flu-like illnesses, other respiratory disorders, and to increased morbidity. Individuals who work in occupations such as metalworking, construction, transportation, and mining are especially susceptible to unsafe exposures because of their proximity to the source of particle generation. Despite the risk to worker health, relatively few are routinely monitored for their exposure due to the time-intensive and cost-prohibitive analytical methods currently employed. The current paradigm for chemical speciation of workplace pollution is outdated and inefficient. Paper-based microfluidic devices, a new type of sensor technology, are poised to overcome issues associated with chemical analysis of particulate matter, specifically the cost and timeliness of exposure assessment. Paper sensors are designed to manipulate microliter liquid volumes and because flow is passively driven by capillary action, analysis costs are very low. The objective of this work was to develop new technology for rapidly measuring Ni, Cu, Fe, and Cr in welding fume using easy-to-use paper devices. This dissertation covers the development of two techniques for quantifying metal concentration: spot integration and distance-based detection. Metal concentrations as low as 0.02 ppm are reported. A method for controlling reagent deposition as well as a new interface for multiplexed detection of metals, is discussed.Item Open Access Dual-fuel combustion of hydrocarbon fuel droplets in lean, premixed methane/oxidizer mixtures in a rapid compression machine(Colorado State University. Libraries, 2018) Gould, Colin M., author; Marchese, Anthony, advisor; Windom, Bret, committee member; Dandy, David, committee memberThe combustion of two fuels with disparate reactivity (dual-fuel) has been shown to be an effective method for increasing fuel efficiency and reducing both fuel costs and pollutant formation in internal combustion engines. Due to recent decreases in the price of natural gas, the incentive has grown to operate engines in dual-fuel mode, where some amount of diesel is substituted with natural gas. Since natural gas is expected to remain less expensive on a per-unit-energy basis than diesel fuel for the foreseeable future, it will continue to be economically advantageous to maximize the substitution percentage of natural gas in dual-fuel engines. However, at higher natural gas substitution percentages, uncontrolled fast combustion (i.e. engine knock) can occur, which limits the load of the engine and can shorten the lifetime of engine components. Emission of unburned methane has also been shown to increase with increasing natural gas substitution percentage. Previous detailed computational engine modeling at CSU with reduced chemical kinetics and simplified spray models has captured these effects but little data are available to validate chemistry and spray models at engine-relevant conditions. In this study, a rapid compression machine (RCM) was used as a platform to provide a high-temperature/high-pressure environment to better understand the thermodynamic, transport and chemical kinetic phenomena of dual-fuel combustion. The RCM was modified to perform evaporation and combustion experiments on single n-alkane fuel droplets in gaseous inert, O2/inert and O2/CH4/inert environments. Droplet evaporation experiments were performed on C5 to C12 n-alkane droplets in inert gas to measure droplet evaporation rates at near supercritical and supercritical conditions (18 bar < P < 35 bar; 450 K < T < 850 K). The Dual-fuel droplet evaporation and combustion experiments were studied using pressure data and images collected a Schlieren optical system. In the combustion experiments, ignition delay of heptane/O2/inert was quantified at elevated pressure and temperature (27 bar < P < 38 bar; 844 K < T < 1251 K). In addition, the process of dual-fuel combustion was captured, showing two distinct ignition events.Item Open Access Electrochemically prepared metal antimonide nanostructures for lithium ion and sodium ion battery anodes(Colorado State University. Libraries, 2016) Jackson, Everett D., author; Prieto, Amy, advisor; Rappe, Anthony, committee member; Dandy, David, committee member; Bailey, Travis, committee member; Henry, Charles, committee memberThe use of energy fundamentally enables and globally supports post-industrial economies and is critical to all aspects of modern society. In recent years, it has become apparent that we will require superior energy technologies to support our society, including improved methods of generating, storing, and utilizing energy resources. Battery technology occupies a critical part of this new energy economy, and the development of electrochemical energy storage devices will be a critical factor for the successful implementation of renewable energy generation and efficiency strategies at the grid, transportation, and consumer levels. Current batteries suffer from limitations in energy density, power density, longevity, and overall cost. In addition, the inherent tradeoffs required in battery design make it impossible to create a single battery that is perfect for all applications. To overcome these issues, the development of low-cost and high-throughput methods, new strategies for materials design, and a comprehensive understanding of electrochemical mechanisms for battery performance is necessary. Herein, an in-depth study on the electrochemistry of a model anode system for rechargeable batteries based on metal antimony alloys produced through an electroplating approach is detailed. The first chapter of this dissertation provides a brief introduction of lithium ion and sodium ion battery technology. In the second chapter, a detailed review of the literature on antimony and metal antimonide alloys for battery anodes is provided. The third chapter details a study on copper antimonide thin films with varying stoichiometry produced through a facile electrodeposition process. In the fourth chapter, stoichiometric Cu2Sb thin films are studied as potential anodes for sodium ion batteries. The fifth chapter details the development of a process for electroplating zinc-antimony alloy thin films onto zinc and their electrochemical properties in sodium ion cells. The sixth and seventh chapters report the synthesis and characterization of copper-antimony alloy nanowire arrays produced through an alumina-templated process. These nanowire arrays are first used in an electrolyte-additive study to show the importance of surface stabilization for high surface area electrodes in chapter five. In chapter six, the rate performance is characterized under different thermal conditions for different compositions of copper-antimony alloy nanowire arrays as an assessment of the kinetic limitations of this electrode. The final chapter briefly describes some preliminary experiments that have been performed on characterizing the electrochemistry of metal salts in a deep eutectic solvent as a potential method for co-deposition of new metal antimonides.Item Open Access Investigation of the growth mechanism of highly branched silica nanowires grown using in-situ Cu-catalyst loading, and the development of electrochemical anodization synthetic methods specifically targeting solid ionically conducting materials(Colorado State University. Libraries, 2023) Boissiere, Jacob Daniel, author; Prieto, Amy, advisor; Finke, Richard, committee member; Rappe, Anthony, committee member; Dandy, David, committee memberGaining a better understanding of the world around us is the fundamental objective of science, with chemistry looking to better understand the processes and applications that occur on a molecular and sub-molecular scale. Developing this better understanding has allowed us to create medicine and computers, begin exploring space and understanding the atom and is a never-ending process of asking questions and testing hypotheses as we work toward an increasingly objective answer. The best that I can hope for, not only in my time in graduate school, but as I move forward in life, is that I have moved this understanding, even in the slightest, in the correct direction. This may be a small impact, but much of the work presented in this dissertation will focus on small things. Two significant research directions will be presented along with work on device and process development for characterization. The first major system that will be discussed is the chemical vapor deposition of highly branched silica nanowires that were grown in a single synthetic step as a result of in-situ Cu-catalyst loading. The second research direction involves the investigation into using electrochemical anodization synthesis as a way to target the formation and discovery of ionically conducting materials. The overall link between these research topics involves the focus on solid inorganic materials, with a broad direction of understanding materials systems, process development and optimization, careful characterization, hypothesis generation, and considerations of potential applications and future directions of the materials and techniques being investigated. Systems of interest could loosely be classified as energy related materials. Both systems provided unique and challenging aspects to understanding the synthetic processes involved as products were formed under highly dynamic environments. Additionally, device and process developments were perused to address systematic variables such as instability of products and improve overall reaction design and therefore reproducibility and significance of results. The first system investigated involved the chemical vapor deposition of silicon-based nanowire products. The initial objective of the project was to investigate the unique structures of highly branched nanowires that were grown through in-situ doping of Cu, and investigate their properties and performance as a potential anode material for use in Li-ion battery devices. The synthetic method used, and the unique structures observed were previously reported by the Prieto research group. The hypothesis was that these products were grown as crystalline Si and being catalytically oxidized due to the presence of Cu and Cu3Si post synthesis. The work presented here disproves this hypothesis, instead proposing that the product is grown as the oxide. Due to this new conclusion, the battery application study was no longer pursued, and investigation instead focused on developing and proposing a new growth hypothesis. This new hypothesis involves the formation of a multi-wire backbone, which is believed to be the first report to directly investigate and explain this phenomenon. The second research direction outlines the motivation, theory, and initial outcomes of attempting to develop a new synthetic methodology for ionically conducting materials through electrochemical anodization. While anodization is itself far from a new synthetic method, it has never been used to synthesize the targeted material systems, nor has it been used to pursue the synthesis of ionically conducting materials generally. Much of the discussion will revolve around the background, motivation, and hypotheses relating to this project. This focus is partially due to the limited success of certain research objectives, but the intention is to hopefully highlight the intrinsic value of the synthetic concept and theory behind it, as well as direct future potential research based on what has been learned. The synthetic results and discussion focus on the anodization synthesis of AgI, the morphologies and crystallographic properties of the materials formed, and insights into the synthetic process. The related systems of CuI and CuxS will also be touched upon, as well as attempts to pursue the synthesis of Na3PS4. Throughout these investigations, a variety of side project and collaborations were worked on, but the one of significance that will be included in the final chapter relates to the development of an air-free sample transfer holder. This was developed to allow the air-free transfer of a surface sensitive material between a glove-box and an X-ray photoelectron spectroscopy instrument. This enables more accurate and meaning data to be collected on samples that could otherwise be modified or compromised through exposure to ambient air before analysis.Item Open Access Microfluidics for environmental analysis(Colorado State University. Libraries, 2018) Gerold, Chase T., author; Henry, Charles S., advisor; Krummel, Amber, committee member; Levinger, Nancy, committee member; Finke, Richard, committee member; Dandy, David, committee memberDuring my graduate dissertation work I designed and utilized microfluidic devices to study, model, and assess environmental systems. Investigation of environmental systems is important for areas of industry, agriculture, and human health. While effective and well-established, traditional methods to perform environmental assessment typically involve instrumentation that is expensive and has limited portability. Because of this, analysis of environmental systems can have considerable financial burden and be limited to laboratory settings. To overcome the limitations of traditional methods researchers have turned to microfluidic devices to perform environmental analyses. Microfluidics function as a versatile, inexpensive, and rapidly prototyped analytical tool that can achieve analysis in field setting with limited infrastructure; furthermore, microfluidic devices can also be used to study fundamental chemistry or model complex environmental systems. Given the advantages of microfluidic devices, the research presented herein was accomplished using this alternative to traditional instrumentation. The research projects described in this dissertation involve: 1) the study of fundamental chemistry associated with surfactant surface fouling facilitated by divalent metal cations; 2) the creation of a microfluidic device to study fluid interactions within an oil reservoir; and 3) the fabrication of a paper-based microfluidic to selectively quantify K+ in complex samples. The first research topic discussed involves observation of dynamic evidence that supports the hypothesized cation bridging phenomenon. Experimental results were acquired by pairing traditional microfluidics with the current monitoring method to observe relative changes to a charged surface's zeta potential. Divalent metal cations were found to increase surfactant adsorption, and cations of increasing charge density were found to have a greater effect on surface charge. Analysis of the experimental data further supports theoretical cation bridging models and expands on knowledge relating to the mechanism by which surfactant adsorption occurs. This work was published in the ACS journal Langmuir (2018, 34 (4), pp 1550–1556). The second project discussed herein focuses on the development of the microfluidic Flow On Rock Device (FORD) that was designed to study fluid interactions within complex media. The FORD was designed to be an alternative to existing fluid modeling methods and microfluidic devices that test oil recovery strategies. Fabrication of the FORD was accomplished by incorporating real reservoir rock core samples into the device. The novelty of this device is due to the simplicity and accuracy by which the physical and chemical characteristics are represented. This project has been accepted for publication pending minor revisions in Microfluidics and Nanofluidics. The final project discussed the creation of the first non-electrochemical microfluidic paper-based analytical device (µPAD) capable of quantitatively measuring alkali or alkaline earth metals using K+ as a model analyte. This device was fabricated by combining distance-based analytical quantification in µPADs with optode nanosensors. Experimental results were obtained using the naked eye without the requirement of a power source or external hardware. The resulting distance-based µPAD showed high selectivity and the capacity to quantify K+ in real undiluted human serum samples. This work has been published in the ACS journal Analytical Chemistry (2018, 90 (7), pp 4894–4900). The research projects briefly described above and thoroughly discussed later within this dissertation were made possible by the utilization of microfluidic devices. These projects investigated various aspects of environmental chemistry without the use of traditional instrumentation or methods. The experimental results that were obtained further the fundamental understanding of surfactant adsorption, provide an inexpensive and accurate model to observe fluid interactions within reservoir rock material, and allow for the selective quantification of K+ in a paper-based device without the use of a power source. The funding for each of these projects was supplied by BP plc and Global Good, as is mentioned accordingly within this dissertation.Item Open Access Modelling and simulation of combustion of dilute syngas fuels in a CFR engine(Colorado State University. Libraries, 2019) Padhi, Geet, author; Windom, Bret C., advisor; Olsen, Dan B., committee member; Dandy, David, committee memberWith increasing interest towards discovery of alternative fuels to act as sources of energy, many conventional internal combustion engines are being modified to operate on these new fuels. Optimization of engine specifications including compression ratio, intake/piston geometry, valve timing, and combustion phasing, can greatly improve performance when an engine is modified to operate on alternative fuels such as syngas and producer gas. However, the inability to predict the combustion characteristics of the alternative fuel, such as burn rates and auto-ignition conditions, is a significant challenge when simulation-based design of an engine is intended. The following thesis describes the development of a predictive model to simulate the combustion of a dilute syngas fuel in a Cooperative Fuel Research (CFR) spark ignited engine. The laminar flame speeds of the unique fuel mixtures calculated using CHEMKIN were coupled with the geometric features of the CFR engine to create a combustion model of the CFR engine in GT-POWER. Using two-zone modelling and detailed chemical kinetics, the model is also able to determine the performance of the engine along with any associated knocking tendency of the fuel and its corresponding operating conditions. Validation and tuning of the combustion parameters were performed through comparison to experimental pressure data taken from the CFR engine. The completed engine model can support the design and selection of operating conditions to maximize efficiency of other spark ignited internal combustion engines when powered by the dilute syngas fuel.Item Open Access Part I: Synthesis and characterization of titania and magnesium nanoparticles for hydrogen production and storage. Part II: Characterization and growth of branched silicon nanowires grown via a simultaneous vapor-liquid-solid and vapor-solid-solid mechanism(Colorado State University. Libraries, 2015) Shissler, Daniel Jay, author; Prieto, Amy, advisor; Shores, Matthew, committee member; Rappé, Anthony, committee member; Van Orden, Alan, committee member; Dandy, David, committee memberTo view the abstract, please see the full text of the document.Item Open Access Reactor design for electrochemical oxidation of the persistent organic pollutant 1,4-dioxane in groundwater(Colorado State University. Libraries, 2018) Cottrell, P. Maxine, author; Blotevogel, Jens, advisor; Sale, Tom C., advisor; Dandy, David, committee memberThe common industrial solvent stabilizer and wetting agent 1,4-dioxane (DX) is one of the most widely occurring organic groundwater contaminants in the United States today. It is a probable human carcinogen, highly mobile in groundwater, and resistant to anaerobic biodegradation. The ineffectiveness of conventional treatment approaches such as stripping and sorption to activated carbon results in a critical need of advanced technologies for the treatment of DX in groundwater. Previous studies have shown that electrochemical oxidation is able to fully mineralize 1,4-dioxane, but testing has thus far been limited to proof-of-principle bench-scale experiments. Consequently, this study addresses the design of a configurable mobile pilot-scale reactor that can be used to test electrochemical degradation performance under site-specific conditions and with different dimensionally stable electrode materials. The goal of this reactor design is to accommodate straightforward scale-up for field applications, and low cost of production so that ultimately multiple modular units can be deployed to operate in series or in parallel. Assessment of critical design parameters in a bench-scale reactor showed that DX degradation rates almost doubled when no inter-electrode solid media were used. No significant differences were observed between operating the reactor in continuous versus batch mode. An additional 57% degradation rate improvement was achieved when the batch reactor was operated with 30-minute polarity reversals as compared with constant polarity. Bench-scale reactor and initial pilot reactor tests with Ti/IrO2-Ta2O5 electrodes were run using a synthetic groundwater solution containing DX in NaCl electrolyte, revealing substantial effects of scale, while DX degradation kinetics were similar. Groundwater from a contaminated industrial site was then treated in the pilot reactor with an apparent anode surface area per order of magnitude DX removal (ASAAO) of 305 h*m2/m3 at an electric energy consumption per order of magnitude DX removal (EEO) of 152 kWh/m3, with relatively minor production of undesirable by-products. The contaminated site groundwater was also treated in a commercial bench-scale reactor with a Magnéli-phase titanium oxide anode, resulting in an ASAAO of 28 h*m2/m3 at an EEO of 176 kWh/m3, but with a high yield of carbon tetrachloride (CCl4) and chlorate (ClO3-), and minor formation of perchlorate (ClO4-). In comparison of the surface-area normalized rates of removal, the commercial reactor was faster than the pilot reactor, but it consumed more energy per order reduction and generated more undesirable reaction by-products, commonly referred to as disinfection by-products (DBPs). Future testing at contaminated field sites will reveal the efficacy of our newly designed reactor, and thus electrochemical treatment, for the remediation of groundwater contaminated with DX and other persistent organic pollutants.Item Open Access Remediation of soil impacted with chlorinated organic compounds: soil mixing with zero valent iron and clay(Colorado State University. Libraries, 2014) Olson, Mitchell R., author; Sale, Tom, advisor; Dandy, David, committee member; De Long, Susan, committee member; Shackelford, Charles, committee memberChlorinated solvents in the environment continue to present an enormous remediation challenge. A primary reason for the difficulty in cleaning up chlorinated solvent source zones involves heterogeneous distributions of permeability and contaminants in natural porous media. A method that can be used to overcome heterogeneity involves use of soil mixing techniques to deliver reagents and homogenize soils. A typical soil mixing application involves admixing contaminated soil with zero valent iron (ZVI) and bentonite (clay). This technology, herein referred to as ZVI-Clay, combines ZVI-mediated degradation of chlorinated solvents with bentonite-induced stabilization. As of December 2013, ZVI-Clay has been applied in 13 field applications, all of which have been viewed as being successful in achieving site remediation objectives. However, our understanding of the processes governing treatment in the ZVI-Clay mixed soil system is rather limited. The overarching goal of the research presented herein is to broaden our understanding of the processes controlling degradation and transport in soils treated via soil mixing with ZVI (or similar reactive media) and bentonite. In support of this objective, research included (a) analysis of field data, (b) initial rate studies, (c) hydraulic conductivity testing, (d) reactive-transport modeling coupled with column experiments, and (e) treatment of hydrophobic compounds. Field data analysis was based on performance data from a ZVI-Clay field application at Camp Lejeune, NC, in which 23,000 m3 of soil initially contaminated with trichloroethene (TCE) and 1,1,2,2-tetrachloroethane (TeCA) were treated with 2% ZVI and 3% bentonite. Within one year of treatment, total chlorinated organic compound (COC) concentrations in soils were decreased by average and median values of 97% and >99%, respectively. Total COC concentrations in groundwater were reduced by average and median values of 81% and >99%, respectively. Total COC reductions by 99.9% or greater were observed in most soil and water sampling locations. Hydraulic conductivity in the treated soil zone was reduced by an average of about 2.5 orders of magnitude. To explain the variations in kinetic data observed following ZVI-Clay field applications, initial-rate batch-reactor studies were conducted under a range of initial TCE concentrations and ZVI concentrations. When TCE concentrations were less than solubility, the Michaelis-Menton kinetic model provided an excellent fit of experimental data. When TCE concentrations were above solubility (i.e., NAPL was present), the degradation rate was independent of the amount of NAPL in the system. The presence of NAPL appears to have had a minor impact (~20% reduction) on the TCE degradation rate. A linear relationship between TCE degradation rate and ZVI amount was observed. Hydraulic characteristics of soils mixed with bentonite were evaluated by conducting column studies and MODFLOW modeling of field-scale systems. Experiments were conducted to evaluate the hydraulic conductivity, K, in two soils types mixed with 0.5 to 4% bentonite (i.e., the range of values typical for ZVI-Clay field applications). In a well-sorted fine sand, with a moderately high initial K (10-4 m/s), the value of K was reduced by about a factor of 10 for each 1% bentonite added to the soils. In a moderately-sorted fine sand with silt, with a low initial K (10-8 m/s), addition of up to 4% bentonite had only minor impacts on K. MODFLOW modeling indicated that surrounding groundwater flow patterns tend to bypass the treated soil body, under steady state conditions, given a reduction in K by at least an order of magnitude. Within the treated soil body, contaminant residence time is extended in approximate proportion to the reduction in K. The concepts of NAPL dissolution, ZVI-mediated degradation, and flow reduction were combined in a mathematical model. The model was then tested using column reactor studies containing NAPL-phase TCE and soils treated with 2% ZVI. The model adequately described TCE elution and formation of degradation products. The model was then used to predict treatment performance following field-scale implementation of ZVI-Clay. Model output predicts that the benefits of reaction are most effectively utilized with a reduction in flow rate by at least 2 orders of magnitude. Finally, enhancements to the ZVI-Clay treatment process were evaluated for treatment of polychlorinated biphenyls (PCBs). Due to their strong hydrophobicity and stable molecular structure, PCBs in the environment have been shown to be much more difficult to degrade than many of the common chlorinated solvents. Thus, alternative types of reactive media were evaluated. Batch experiments were conducted to evaluate zero valent metals (ZVM), ZVM + Pd-catalysis, and emulsified zero valent iron (EZVI) for dechlorination of PCBs in systems with and without soil. In water-based systems, ZVM with a Pd-catalyst facilitated rapid destruction of 2-chlorobiphenyl (half-life < 2 hr), while ZVM alone did not achieve any measurable degradation. In the presence of soils, EZVI was the only approach that resulted in a clear enhancement in PCB dechlorination rates. The results suggest treatment of PCBs in the presence of soil presents a much greater challenge than treatment of aqueous phase PCBs; however, treatment of PCBs in soil can benefit from enhanced desorption and a persistent reactive media.Item Open Access Situational strategic awareness monitoring surveillance system (SSAMSS)(Colorado State University. Libraries, 2023) Maldonado, Kenly R., author; Simske, Steven J., advisor; Miller, Erika, committee member; Herber, Daniel, committee member; Dandy, David, committee memberThis dissertation takes a Systems Engineering approach for the development of a cost-effective, deployable remote sensing materials safeguarding system. This co-called system-of-systems undergoes the major portions of the Systems Engineering development process to assure with confidence that a Situational Strategic Awareness Monitoring Surveillance System (SSAMSS) is a competitive product considered for actual development. The overall assessment takes a strategic approach by using selective tools to create, confirm and consider whether SSAMSS as a product idea ultimately should be developed into an actual prototypical Model (Engineering Model). Although the dissertation explores whether a prototype should be considerate with confidence and risk consideration it does not actually dive into the physical development of the model due to limited time and actual funding. Through the Systems Engineering V-Model, SSAMSS as a product and enterprise is vetted from the customer needs analyses through unit testing (the bottom of the V-model). This is the point where an actual customer would decide to continue the to incorporate SSAMSS into integration and testing, prototype to operations, maintenance, and retirement. Through simulations, assessment, and analysis it has been determined that SSAMSS as a product and enterprise is a viable option to supersede current material safeguarding systems that are competitive in the marketplace today.