Engineering Commons^™

Novel Breath Collection Techniques For Detection Of Covid-19., James Morris

Electronic Theses and Dissertations

Volatile Organic Compounds (VOC) generated endogenously in the human body can be used to detect diseases that induce oxidative stress and inflammation. Breath analysis has been used for the detection of diseases such as COPD, Depression, Lung Cancer and most recently COVID-19. Methods such as Exhaled Breath Condensate (EBC), Sorbent Tubes, Solid Phase Microextraction (SPME), and silicon microreactors have shown considerable capability in extracting and concentrating trace VOC’s present in human breath. Silicon microreactors functionalized with capture agents to derivatize carbonyl compounds are effective but the overall maximum flow rate of breath sample possible during analysis is low, making direct …

Addition Of Process Control Experiment To Unit Operations Ii Laboratory., Bradley Esselman

Electronic Theses and Dissertations

Process control is an essential aspect of manufacturing, contributing to improved process safety, efficiency, product consistency, and energy optimization. Chemical engineers are often responsible for ensuring the safe, efficient, and cost-effective operation of industrial processes, and process control plays a pivotal role in accomplishing this.

Chemical engineering students at the University of Louisville complete the course, Elements of Process Control, during the second semester of their fourth year. This lecture-based course offers limited hands-on, practical experience. To supplement the lack of hands-on experience in the classroom, a new process control experiment was designed and implemented into the Unit Operations …

The Study Of Corrosion On Additive-Manufactured Metals., Braydan Daniels

Electronic Theses and Dissertations

The purpose of this study was to investigate and compare the corrosion mechanisms between wrought and additive-manufactured (3D-printed) copper and stainless steel. The experimental procedure consisted of measuring the open circuit potential, electrochemical impedance spectroscopy, linear sweep voltammetry, Tafel analysis, surface topology, and scanning electron microscopy for each metal within salt water, tap water, sulfuric acid, and synthetic body fluid (excluding copper in synthetic body fluid).

Overall, printed stainless steel was more corrosion-resistant than wrought stainless steel in tap water and synthetic body fluid based on OCP, LSV, and surface topology results. Additionally, printed copper was more corrosion-resistant than wrought …

Novel Microdevices To Analyze Toxic Volatile Organic Compounds., Sujoy Halder

Electronic Theses and Dissertations

There has been a growing interest to measure volatile organic compounds (VOCs) in a range of environmental applications. The presence of toxic VOCs in the air has been associated with serious health problems including asthma, central nervous system dysfunction, cardiovascular disease and cancer, etc. Different analytical instruments such as gas chromatography-mass spectrometry (GC-MS) and sensor systems, such as metal oxide sensors are used to analyze VOCs. However, challenges still exist in the detection of airborne VOCs because of their trace concentration and interference with complex gas mixtures. In this dissertation, two microfabricated devices, a sensor array and a micropreconcentrator were …

Investigation Of Light Management Strategies And Photochemistry Of Si/Tio2 Tandem Microwire Slurries For Solar Hydrogen Generation., Saumya Gulati

Electronic Theses and Dissertations

The intermittent nature of the Sun makes it difficult to use it as a primary source of electricity and often needs to be supplemented by electricity from the grid which comes from fossil fuels. This motivates the need for solar energy storage. Photoelectrochemical (PEC) water-splitting has been explored as a means to convert solar energy into hydrogen (and oxygen), which can be stored as fuel. The current method of coupling PV and electrolyzer units has been widely commercialized, however, the cost of H₂ generated is far from the target of $1/kg set by the DOE under the Energy EarthShot …

Synthesis, Property Tuning And Degradation Studies Of Phosphorene-Based Materials., Usman Onuminya Abu

Electronic Theses and Dissertations

Two-dimensional (2D) layered materials have sparked the interest of researchers because of their interesting properties drawn from quantum confinement effects, elevated density of states (DOS), increased surface area, increased active sites, etc. Phosphorene, an interesting addition to the 2D material family in 2014, has interesting properties such as in-plane anisotropy, elevated carrier mobility and thickness-dependent bandgaps that have made it a material of intense interest. Furthermore, there have been theoretical studies predicting that phosphorene could be made even more versatile by intercalating alkali atoms into its layers. Intercalation has proven to be a veritable tool for synthesis, modification, transformation, and …

Chloramine Devulcanization Of Waste Rubber., Patrick Kroeger

Electronic Theses and Dissertations

The disposal of waste rubber, particularly tire rubber, continues to pose a challenge in the 21st century. As a result, most end-of-life tires (ELTs) are either dumped in landfills or burned as tire-derived fuel. Chloramine devulcanization may offer a viable solution to this problem. Chloramine devulcanization is a low-temperature, low-pressure, process that selectively breaks sulfur crosslinks while preserving the polymer backbone. Chloramine devulcanization enables the recovery of chloramine recovered carbon black (CrCB) and devulcanized rubber (CdR) as separate products. Initial analysis of CdR revealed that it was formable and malleable, suggesting that crosslinking was absent. Spectroscopy showed that CdR contained …

Compositional Engineering Of Precursor Inks For Intense Pulsed Light Compatible Deposition Of Perovskite Solar Cells., Blake Martin

Electronic Theses and Dissertations

Perovskite solar cell (PSC) technology offers a promising alternative to silicon-based photovoltaics (PVs), but challenges of stability, module efficiency, and scalability hinder commercialization. This study aims to explore potential solutions to overcome scalability and cost limitations of PSCs, addressing technical barriers to commercialization. We adapt the conventional three-stage perovskite deposition process (deposition, translational phase formation, and annealing) for scalable platforms using wide-area depositions, meniscus coating methods, forced laminar airflow drying, and radiative annealing methods, making it more suitable for roll-to-roll fabrication. A technoeconomic analysis shows that large-scale operations can produce solar films at a cost of $0.04-$0.10 per watt, making …

Detection Of Toxic Aldehydes In Aerosols Of Electronic Cigarettes., Ellie Bess Reed

Electronic Theses and Dissertations

Over the past decade, use of electronic cigarettes (e-cigarettes) has increased in the younger generations of the United States. With the broad range of flavors and devices distributed on the market, American youth are prime marketing targets for the e-cigarette industry. To create a more regulated market, research of this thesis has been conducted on newer generations of e-cigarette “MOD” devices to examine how e-cigarette battery power output and coil temperature, concentrations of propylene glycol and vegetable glycerin, added flavorings (strawberry, mango, and menthol), and the presence of nicotine affect generation of aerosol particles and aldehydes in aerosols emitted by …

Anion Alloying Of Iii-V Semiconductors For Water Splitting., Sonia Calero-Barney

Electronic Theses and Dissertations

The challenge of solar energy conversion and storage translates into the discovery and development of semiconductor materials that can transform sunlight energy into electricity and/or high-energy-density fuels in a cost-effective way. From the solar energy conversion perspective, cation-alloyed III-V solar cells hold record-breaking energy conversion efficiencies, while anion-alloyed III-V’s are particularly interesting for photoelectrochemical hydrogen generation. The major challenge for the adoption of III-V-based technologies lies in the high manufacturing costs of established synthesis techniques and the difficulty to control the composition of ternary alloys. One of the materials investigated in this work is GaSb_zP_1-z. Thermodynamic …

Engineering Lewis Acidic Materials For Biomass Conversion And Battery Applications., Md Anwar Hossain

Electronic Theses and Dissertations

My long-term goal is to develop catalytic systems to produce renewable energy for a sustainable society. The overall research objective of my dissertation is to advance understanding of Lewis acidic materials for (1) conversion of renewable lignin into phenolics and (2) enhanced cycling stability of lithium metal batteries to safely store renewable electricity from wind and solar, thereby laying the groundwork for our transition to a sustainable society. Petroleum is a conventional feedstock for current transportation fuels (gasoline, diesel, and jet fuels). However, petroleum is a finite resource and produces greenhouse gases (CO₂ and CH₄) upon processing, …

Surface-Functionalized Chemiresistive Films That Exploit H-Bonding, Cation-Pi, And Metal-Halide Interactions., Prasadanie Karunarathna Adhihetty

Electronic Theses and Dissertations

The development of gas sensors for detection of volatile organic compounds (VOCs) has been of interest in the sensing field for decades. To date, the use of metal nanoparticle-based chemiresistors for trace VOC detection, particularly gold nanoparticle-based sensors, is of great interest due to their high chemical stability, ease of synthesis, unique optical properties, large surface to volume ratio, and high level of conductivity. Much effort has been devoted towards gold monolayer protected clusters (Au MPCs) as chemiresistors to detect harmful VOCs. The present thesis documents the results of our efforts to exploit the advantages of functionalized Au MPCs chemiresistors …

Structural, Charge Transport, Gas Sensing, Magnetic, Pseudocapacitive, And Electrocatalytic Properties Of Perovskite Oxides., Surendra Bahadur Karki

Electronic Theses and Dissertations

Perovskites are functional materials with the general formula ABO₃ (A = alkali, alkaline earth or lanthanoid cations and B = transition metal or main group cations). These materials are marked by a variety of crystal structures and interesting properties such as colossal magnetoresistance, ferroelectricity, multiferroicity, superconductivity, pseudocapacitance, gas sensing, charge transport, and electrocatalytic properties. The formula of perovskite can be written as AA’BB’O₆, when there is ordering between two cations over A and B-sites. Such compounds are called double perovskite oxides. Some amount of oxygen could be lost from crystal structure without decomposition of the phase. Such …

Development Of Porous Solid Acid Catalysts For Lignocellulose And Plastic Upcycling., Mohammad Shahinur Rahaman

Electronic Theses and Dissertations

My goal is to develop chemical processes for transforming waste to solve environmental problems and enhance sustainability. Environmental problems such as pollution and massive amounts of waste are the main drivers that stimulate my research ideas. I focused on creating novel, efficient catalytic processes for converting polymeric waste "feedstocks" into high-value chemicals by integrating my expertise in catalysis, materials science, and synthetic chemistry to develop porous solid catalytic materials. During my Ph.D., I focused on two polymeric feedstocks, lignocellulose, and discarded plastic.

Early in my Ph.D. journey, I focused on catalytic upcycling of lignocellulose. Lignocellulosic biomass is cost-effective, abundant, and …

Materials And Interfaces For Electrocatalytic Hydrogen Production And Utilization., Alexander Jiya Gupta

Electronic Theses and Dissertations

Mass industrialization over the last few centuries has created a global economy which is dependent upon fossil fuels to satisfy an exponentially increasing demand for energy. Aside from the possible depletion of this finite resource, the combustion of fossil fuels releases greenhouse gases into the atmosphere which cause the global temperature to rise – a phenomenon which has already begun to create geologic and geopolitical instability and shows no signs of abatement. One proposed method to rid humanity of its dependence on fossil fuels is to use green hydrogen as an energy carrier. In this scheme, excess electricity from a …

Scalable Synthesis Of Alumina Nanowires By Wet Chemical Method., Luis N Moreno

Electronic Theses and Dissertations

To satisfy an increasing demand for large-scale processes for producing alumina nanomaterials, a wet chemical method was evaluated. A potassium salt precursor was combined with aluminum to produce alumina – based nanowires. Compared with current methods such as thermal oxidation, sol-gel, and laser ablation, this method is highly scalable due to relatively low energy requirements and the ability to carry out the primary reaction under ambient conditions. The nanowire samples were evaluated using SEM, XRD, BET, and TEM to confirm morphology, phases present, and surface area. A porous nanowire structure was confirmed which has a BET surface area of 324.6 …

Synthesis, Crystal Structure And Ionic Conductivity Of Ruddlesden-Popper Oxide Materials: Effects Of Ionic Radii And Defects On Lithium-Ionic Conductivity., Selorm Joy Fanah

Electronic Theses and Dissertations

Layered perovskite oxides of the Ruddlesden-Popper (RP) type structure can be good lithium-ion conductors for solid electrolyte applications in all-solid-state batteries, due to the large gap separating octahedral layers which can be useful pathways for Li-ion conduction. However, little work has been done on their lithium-ion transport properties in these materials despite their interesting structural properties. This work highlights the synthesis and study of the ionic conductivities in a series of n = 2 and 3 Ruddlesden-Popper oxides, as part of an ongoing investigation in search of alternative solid electrolyte materials. Several different strategies were employed for the enhancement of …

Towards Long Term Colloid Suspension In A Vertically Rotated System., Md Mahmudur Rahman

Electronic Theses and Dissertations

Within a colloidal suspension gravity may compromise the observation of governing physical interactions, especially those that are weak and/or take significant time to develop. Conducting the experiment in a long-term microgravity environment is a viable option to negate gravitational effects, though significant resources are required to do so. While it may not be possible to simulate long-term microgravity terrestrially, particles can resist quick sedimentation in a confined suspension system rotating vertically with appropriate rotation speed. The goal of the investigation is to demonstrate the existence of long-term particle suspension regime for a certain colloidal suspension while characterizing colloidal behavior due …

An Introductory Study Of Coal Fly Ash Enhancement For Heavy Metal Removal In Wastewater Treatment., Samuel T. Romes

Electronic Theses and Dissertations

Coal Combustion Products are the materials that remain after pulverized coal is burned to generate electricity. The fine portion, fly ash, has many re-use capabilities across various industries. Most recent data shows that approximately 60% of fly ash produced in the United States was used with the largest re-use being concrete additives. This work aims to enhance fly ash via hydrothermal treatment in order to expand the re-use capabilities of the material. These materials were tested as adsorbents for heavy metal removal from wastewater samples. The metals tested for removal were Copper (II) Acetate, Cadmium Chloride, Boric Acid, Sodium Selenite, …

Solvent Engineering Of Molybdenum Disulfide Electrocatalyst For Hydrogen Evolution., Robert Carl Spalding

Electronic Theses and Dissertations

Energy is at an exponentially growing demand, and to keep up with these demands new technologies for renewable energy have received increased attention. Hydrogen plays a vital role in water electrolysis and fuel cells, as the hydrogen evolution reaction (HER) is the main step water splitting process. Most of the current electrocatalysts for HER are dominated by platinum and other precious metals due to their low over-potential and small Tafel slope, however, they are extremely costly. For this reason, cost-effective non-precious metal catalysts must be developed. Transition metal dichalcogenides, such as molybdenum disulfide (MoS2), are abundant and have recently shown …

Aggregation Dynamics Of Bulk Nanoparticle Haloing Systems And The Influence Of Non-Ambient Temperatures., Marzieh Moradi

Electronic Theses and Dissertations

One of the methods of assembling colloids into 3D crystal structures is through the use of nanoparticle haloing. Nanoparticle haloing is a stabilization mechanism in binary particle suspensions possessing both a size and charge asymmetry, with which the nanoparticles aid in the bulk suspension’s stability. By altering the volume fractions of nanoparticles, it is possible to control the effective repulsion between the microparticles. Understanding the colloidal interactions and aggregate crystallinity as a function of nanoparticle concentration, temperature, and time are key challenges in developing future materials and designing crystalized 3D colloidal systems. In this study, we investigated the effect of …

Wetting And Drying Dynamics For Tio2 With Pbs Quantum Dots., Kelly M. Lee

Electronic Theses and Dissertations

Initial solar cells utilized silicon and alloys for their economic viability. Photoelectrochemical photovoltaic cells were discovered with technological advancement which increased solar efficiency and further improved economic feasibility leading to quantum dot sensitized solar cells. Lead sulfide quantum dots and titanium dioxide were studied for wetting and drying effects. Zeta potential, pH values, SEM, and optical microscopes quantified or observed the colloidal suspension and dried sample behavior. Combined mixtures of lead sulfide and titania were dried at 3.6 pH and 12.56 pH values. This due to the observed zeta potential isoelectric point of titania, and behavior showed increased stability occurring …

Mixed Metal Oxide Nanowires Via Solid State Alloying., Veerendra Atla

Electronic Theses and Dissertations

Mixed metal oxide materials with composition control find applications in energy conversion and storage processes such as heterogenous catalysis, photoelectrochemical catalysis, electrocatalysis, thermal catalysis, and lithium-ion batteries. Mixed metal oxides and/or complex oxides with composition control and in one-dimensional form as nanowires could be interesting to various catalysis applications due to control on single crystal surfaces, active sites, acidity versus basicity site density, and oxygen vacancies. The major challenge is to synthesize mixed metal oxide nanowires beyond binary oxides with composition control. In this dissertation, solid state alloying of binary oxide nanowires with solid and liquid precursors is studied to …

The Study Of Copper Corrosion Mechanisms Using Electrochemical Experimental Techniques., Evan Grimm

Electronic Theses and Dissertations

The purpose of this study was to discover and thoroughly explain the corrosion mechanisms of copper in saltwater, tap water and deionized water, and to apply these methods and findings when testing the corrosion mechanisms of other materials. The experimental procedure consisted of measuring the open circuit potential, electrochemical impedance spectroscopy, linear sweep voltammetry, and Tafel analysis.

The copper was found to corrode at a greater rate in saltwater, followed by tap water then deionized water, with a larger difference between saltwater and tap water than between tap water and deionized water. Each reaction was found to be both kinetically …

Exploring Meerwein-Ponndorf-Verley Reactions Using Metal Organic Framework Catalysts., Yuehan Zhou

Electronic Theses and Dissertations

The Meerwein–Ponndorf–Verley (MPV) reaction is a reaction that is used to reduce aldehydes and ketones to the corresponding alcohols with the added use of catalysts. The common metal triflate catalysts used in MPV reduction incur tremendous environmental hazards and high operational costs. The use of Metal-Organic Frameworks (MOFs) as catalysts can be an alternative due to MOFs’ extraordinarily high surface areas, ultrahigh porosities, tunable pore sizes, modifiable internal surfaces, and numerous framework structures. Moreover, using MOFs as catalysts for MPV hydrogenation is economically viable due to low operational and material costs. This study involves using MOF-808 (Hf) in the MPV …

Modified Electrode Surfaces With Hydrogen Evolution Reaction Catalysts Derived From Electropolymerized Complexes With Redox Active Ligands., Amanda Mae Arts

Electronic Theses and Dissertations

The demand for energy is growing exponentially, and to keep up with these demands new technologies for renewable energy have received increased attention. Hydrogen is one of the most promising energy sources for the future and plays a vital role in water electrolysis and fuel cells, as the hydrogen evolution reaction (HER) is the main step in the water splitting process. To increase the reaction rate and improve efficiency for the water electrolysis, catalysts are used to minimize the overpotential.

Most of the current electrocatalysts for HER are heterogeneous in nature and are dominated by platinum and other precious metals …

Room Temperature Alkali Treatment Of Rice Straw For Enhanced Enzymatic Hydrolysis., Seth Mains

Electronic Theses and Dissertations

Due to the pollution of fossil fuels due to greenhouse emissions, researchers continue to search for alternative methods that allow for the clean production of energy, fuels, and polymer fibers. A method currently under investigation is the use of lignocellulosic biomass as a solution to current problems with energy and polymer fiber production. Through the process of pretreatment, possibilities for lignocellulosic biomass expand due to improved accessibility of the cellulose and hemicellulose which can be broken down via enzymatic hydrolysis into C5 and C6 sugars such as xylose and glucose. This study investigated the fermentation of the rice straw into …

Predicting Henry's Law Constants Of Volatile Organic Compounds Present In Bourbon Using Molecular Simulations., Christopher A Abney

Electronic Theses and Dissertations

Henry’s Law describes the partitioning of molecules into liquid and gas phases at low concentrations. Henry’s Law, which is based upon a species-dependent constant and the gas phase partial pressure, is useful for predicting phase behavior of dilute solutes. However, Henry’s Law constants are difficult to measure experimentally or to predict using structure-property or thermodynamic models. Herein, molecular simulations were used to calculate Henry’s Law constants for 18 volatile organic compounds (VOCs) present in bourbon. The novel simulations analyzed solvation thermodynamics of small organic molecules in 120 proof ethanol. A fast-growth non-equilibrium free energy method was used in which the …

Image Analysis Of Charged Bimodal Colloidal Systems In Microgravity., Adam J. Cecil

Electronic Theses and Dissertations

Colloids are suspensions of two or more phases and have been topics of research for advanced, tunable materials for decades. Stabilization of colloids is typically attributed to thermodynamic mechanisms; however, recent studies have identified transport or entropic mechanisms that can potentially stabilize a thermodynamically unstable colloidal system. In this study, suspensions of silsesquioxane microparticles and zirconia nanoparticles were dispersed in a nitric acid solution and allowed to aggregate for 8-12 days in microgravity aboard the International Space Station. The suspensions were subsequently imaged periodically at 2.5x magnification. Due to the inadequacy of existing image analysis programs, the python package “Colloidspy” …

Mapping Three Dimensional Interactions Between Biomolecules And Electric Fields., Joseph Patrick Brian P.E.

Electronic Theses and Dissertations

Electroporation is a technique that induces the formation of open pores in cell membranes by the application of an electric field. Electroporation is widely practiced in research and clinical work for transfection of genetic sequences and drug molecule transport through the membrane barrier. However, a full theoretical explanation of the molecular mechanisms and thermodynamics responsible for pore formation, structure, and longevity does not yet exist. Advances in molecular dynamics simulations have enabled theoretical studies of electroporation with previously unobtainable fidelity spanning biologically relevant timescales. All-atom simulations utilizing the recently developed method of computational electrophysiology demonstrate that pore size correlates to …