Doctor of Philosophy, University of Akron, 2025, Chemical Engineering

Green chemistry and sustainability are key drivers for the next generation of organic coatings. Reducing hazardous material use and energy consumption is a primary focus. Polyurethanes (PU) hold a significant share of polymer production but causes environmental concerns due to the toxic isocyanates. Non-isocyanate polyurethanes (NIPU) offer a promising alternative with non-toxic raw materials and simplified synthesis. Additionally, bio-based feedstocks have enabled the development of sustainable NIPUs with high bio-based content, low volatile organic compound (VOC) emissions, energy saving, and rapid curing. This dissertation explores various strategies to explore the sustainable NIPU-based coatings and enhance their performance. First, a 2K waterborne PU system was developed using thiol-ene click chemistry, demonstrating that with optimized photoinitiator content, sunlight curing can achieve performance comparable to UV curing. Then, a 1K waterborne NIPU epoxy hybrid system was synthesized from cyclic carbonates, bio-based amines, and epoxy resins, enabling tunable thermal stability, mechanical properties, and general coating performance. Additionally, a linseed oil-based waterborne NIPU was obtained. The cyclic carbonates were synthesized through a novel strategy resulted in pendant functional groups with higher reactivity than other vegetable-oil based cyclic carbonate. The NIPU coatings showed excellent solvent resistance, impact resistance, and adhesion, comparable to solvent-borne and commercial PU coatings. In another work, black near-infrared (NIR) reflective pigments were incorporated into waterborne PU systems to explore the potential applications of the NIPU coatings. The pigments could influence film formation, gloss, and thermal insulation, while enhancing crosslinking density, tensile strength, and Young's modulus. Finally, a UV-curable hybrid NIPU was developed by incorporating glycidyl methacrylate (GMA) into amine-terminated NIPUs, significant (open full item for complete abstract)

Master of Science (M.S.), University of Dayton, 2024, Chemical Engineering

This study uses molecular simulation to understand the adsorption and transport properties of novel single-walled zeolitic nanotubes (SWZNTs) in a variety of molecular environments and to provide a fundamental understanding of the behavior of these new materials in various separation applications within both gaseous and liquid environments. Such an understanding will aid in the development of new implementations of this material and lead to improved separation techniques for various molecular species. Classical molecular dynamics simulations treat the movement of atoms/ molecules with Newton's equation of motion and are often used to study the physical transport/ adsorption behavior of various nanoporous materials. We have applied these techniques to the study of ZNTs and the behavior of liquid and gaseous adsorbates. In this study, a range of Si/Al ratios was examined to determine their effects on the adsorption capacities and selectivities for various gases and liquids, including carbon dioxide, acetylene, CO2 /C2H2 mixtures, and solvated NaCl. Transport properties were analyzed to assess diffusion rates under different conditions. The study reveals that with an increase of the Si/Al ratio of the ZNTs, the ability of the material to interact with the polar molecules decreases, and the hydrophobicity increases, which makes these ZNTs suitable for the separation of non-polar gas and water-resistant applications. On the other hand, a lower Si/Al ratio increases the surface acidity and favors the adsorption of polar molecules, which could be beneficial for processes requiring strong adsorbent-adsorbate interactions. These outcomes offer promising guidance for the development of zeolitic nanotubes with tailored structures to meet specific applications in gas separation, catalysis, and environment protection. Based on the structural and chemical characteristics, zeolitic nanotubes have been recognized as the suitable materials for the purposes of adsorption and mole (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Chemical Engineering

Optimization plays a critical role in the chemical engineering industry due to its potential to improve efficiency, safety, sustainability, and profitability in various processes. While modern solvers are highly effective at addressing optimization problems, they typically require a comprehensive understanding of the underlying mathematical models. However, many chemical processes are complex, difficult to model, and computationally expensive to evaluate, making traditional optimization methods less applicable in these scenarios. The Bayesian optimization (BO) framework is a particularly promising approach for solving these problems, which uses Gaussian process (GP) models and an expected utility function to systematically tradeoff between exploitation and exploration of the design space. BO, however, is fundamentally limited by the black-box model assumption that does not take into account any underlying problem structure. A more realistic assumption is the idea of \textit{grey-box} models, which contain both black-box (unknown) and white-box (known) components. In this thesis, we develop a set of novel approaches for constrained grey-box optimization problems. We first propose a soft-constrained BO method with theoretical guarantees that can outperform standard BO. Next, we develop a novel framework, COBALT, for grey-box optimization problems that combines multivariate GP models with a novel constrained expected utility function. By exploiting composite structure in the objective and constraint functions, we are able outperform traditional black-box approaches by several orders of magnitude. Next, we discuss ways to improve this approach to better handle noisy functions and to establish theoretical guarantees. Specifically, we incorporate the concept of quantile functions, enabling us to specify confidence levels for both the constraints and the objective. We term this new algorithm CUQB, which we compare with our previous works and state-of-the-art black-bo (open full item for complete abstract)

Master of Science (MS), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

The objective of this research is to continue development of the flowtube, a new type of test equipment developed at the ICMT. Baseline testing is commonly used to validate models and ensure understanding of the electrochemical system. Baseline mass transfer experiments were performed using a rotating cylinder electrode (RCE). Baseline corrosion experiments were completed using an RCE as well as a rotating disk electrode (RDE). Mass transfer within the RDE system was also successfully modeled using computational fluid dynamics (CFD) software Ansys Fluent. Experimental and simulated results were validated using well known and accepted correlations. Validation of the CFD simulations is vital because no physical prototype for the flowtube currently exists to compare with the CFD results. The RDE simulations will serve as a baseline to prove that Fluent is capable of performing accurate mass transfer calculations and potentially future corrosion simulations. Current testing apparatuses for flowing environments tend to be large and/or difficult to use in a small-scale lab. To combat this, the flowtube cell can create a controlled single phase flow regime in a glass cell or autoclave and can test 3 samples at one time in its most recent revision. A new revision is currently being created, so the flowtube was modeled using CFD in order to determine how design alterations will affect the flowing environment within the glass cell. The flowtube hydrodynamics have been successfully modeled using Ansys Fluent. This model can illustrate fluid flow in the glass cell around the flowtube apparatus in both steady state and transient conditions. This model will continue to be expanded upon in the future to reflect the design considerations for the next prototype version. Design considerations and their impact on the hydrodynamics of the flowtube system were analyzed through this research.

Master of Science, Miami University, 2024, Chemical, Paper and Biomedical Engineering

Dehydrating glucose efficiently into 5-hydroxymethylfurfural (HMF) has been a heavily researched topic, particularly focusing on the use of more sustainable heterogeneous catalysts. This thesis highlights the potential of wood-derived biomass as a sustainable biomass source for catalyst production, contributing to the development of innovative, bio-based chemicals. This study presents the synthesis, characterization, and application of wood-derived catalysts derived from softwood, deinked paper sludge (DPS), and hardwood for the efficient conversion of glucose to 5-hydroxymethylfurfural (HMF). The prepared catalysts were characterized by BET, FTIR, TGA, and XRD analyses. Prepared catalysts were used in the conversion of glucose to HMF in a single phase at 130oC, and the effect of temperature was studied. The highest yield of HMF, 22.67% in a single phase was obtained from a sulfonated DPS catalyst. Dehydration of glucose to HMF in biphasic water: MIBK was also carried out, and an HMF yield of 30.34% was obtained. At the end of the reaction, the catalysts were easily recoverable through filtration. Overall, this work shows that biomass-based activated carbon catalysts are promising for converting glucose to HMF.

Master of Science, The Ohio State University, 2024, Chemical Engineering

Hydrogen and Syngas are versatile chemicals dense in energy with numerous applications in the industry. Reducing the carbon footprint of their production can help counter global warming. Since conventional methods using fossil fuels lead to copious amounts of CO2 emissions, using renewable, carbon-neutral fuel sources like biogas and biomass while sequestrating CO2 can make the process carbon-negative. This can be achieved using multi-reactor iron oxide chemical looping (CL) systems. A 3-reactor Chemical Looping Hydrogen Generation System (CLHG-3R) generates a pure stream of Hydrogen, and a 2-reactor system converts biomass to high-purity syngas efficiently. The reactor conditions are optimized in this study to account for the high composition variability of these feedstocks. These fuels although renewable, have their challenges. Biogas contains high amounts of CO2 and numerous trace impurities while tars are formed significantly during biomass gasification. Chemical looping systems have a proven capability of dealing with these issues. Experimenting with process parameters like reactor temperatures, residence times, feed composition and flowrates of reactants leads to optimizing the system.

Doctor of Philosophy, Case Western Reserve University, 2024, Chemical Engineering

Lowering energy-related CO2 emissions of the U.S. requires the implementation of renewable energy sources to generate electricity. These sources, e.g. solar and wind power, are intermittent in their output, necessitating some form of grid-scale energy storage. Redox flow batteries, particularly hybrid flow batteries based on zinc (Zn), are a highly attractive solution due to their high energy density, scalability, earth-abundance of Zn, and usage of safer aqueous electrolytes as opposed to flammable organics. However, Zn has notable problems such as forming dendrites during high-rate deposition and spontaneous corrosion in acidic and alkaline electrolytes leading to substantial self-discharge of a battery over time. To address these issues, significant research has been conducted on electrolyte additives that can suppress dendrite formation and prevent corrosion, but many of these conventional additives also polarize the electrode and harm battery energy-efficiency. In the present work, a novel additive, benzyldimethylhexadecylammonium chloride (BDAC), is shown to markedly suppress Zn corrosion (battery self-discharge) rate in a pH = 3 ZnSO4 medium without harming (i.e., by minimizing overpotential losses) the high-rate deposition or stripping performance of Zn. Cyclic voltammetry (CV) measurements show BDAC induces hysteresis, where the electrode can either exhibit passivity or electrochemical activity at a given electrode potential depending on the scan direction. The hysteresis is a result of complex surface adsorption and deactivation behavior of BDAC on Zn. An additive adsorption-deactivation model is proposed which captures above behavior and shows that, at low current densities (i.e. low BDAC deactivation rates), the electrode surface tends towards full additive coverage while, at higher deposition or stripping rates (i.e. rapid BDAC deactivation), the electrode surface tends towards a coverage depending on the additive's adsorption and deactivatio (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2024, Chemical Engineering

The aim of this work is to draw links between 1-D pitting corrosion in literature and crevice corrosion in Alloy 625 and SS 316L in chloride-containing environments. Crevice corrosion initiation, propagation, and repassivation were studied using real-time optical imaging and UV spectroscopy, and the crevice corrosion mechanism was investigated for different cases with the ultimate goal of finding a unifying mechanism for crevice corrosion that is in line with 1-D pitting corrosion. In the first part of this work, crevice corrosion was investigated for LPBF AM Alloy 625 specimens in comparison to the conventionally wrought condition. The AM specimens tested were of two different orientations with respect to the build platform. In addition, the tests were carried out for specimens of the as made or not treated condition as well as specimens that were subject to post manufacturing heat treatments including stress relieving, solution annealing, and solution plus stabilization annealing. Hence, the effect of heat treatment and build orientation on the susceptibility of LPBF additively manufactured Alloy 625 to crevice corrosion was investigated. There was not sufficient evidence that build orientation affects crevice corrosion susceptibility. Nevertheless, it has been shown that heat treatment affects crevice corrosion susceptibility. In addition, though the crevice corrosion susceptibility of as made AM Alloy 625 was not remarkably different from that of wrought 625, solution annealing improves crevice corrosion performance of the AM specimens beyond that of the wrought condition. Crevice corrosion performance differences could be explained with microstructure reflected in the corrosion morphology. Nevertheless, the different AM alloys studied followed the same kinetics/mechanism as the wrought alloy with similar trends in current density and repassivation potential. Such kinetics/mechanisms appear in literature for 1D pits supporting the applicability of the “1D (open full item for complete abstract)

Doctor of Philosophy (Ph.D.), University of Dayton, 2024, Mechanical Engineering

Aviation turbine fuel is a complex mixture comprised of thousands of compounds. While organo-oxygen, nitrogen, and sulfur heteroatomic compounds are present in minute quantities (<0.1% by mass), their presence significantly influences fuel thermal stability. In response to the limitations of existing analytical methods, this study developed and validated a novel analytical approach employing hydrophilic interaction liquid chromatography (HILIC) in conjunction with high performance liquid chromatography (HPLC) with electrospray ionization and quadrupole time-of-flight mass spectrometry (ESI-QTOF). The HILIC method offers numerous advantages including rapid and straightforward sample preparation, without the need for extraction, thereby preserving compounds of interest. Moreover, it offers a way to capture precise compound data enabling chemometric analysis for the prediction of the behavior of the complex mixture that is aviation turbine fuel. Development of the HILIC method found column configuration, mobile phase composition, solvent gradient, re-equilibration time, injection volume, dilution factor, and sample solvent to be significant factors effecting separation efficiency and repeatability. For a sample dataset, optimized using a single aviation turbine fuel, retention time shift was able to be reduced from 0.4 minutes and 2.0% relative standard deviation (RSD) to approximately 0.1 minutes with RSD of 0.4% using the newly developed method. In addition, a high number of untargeted molecular features (944) and targeted amines (121) were able to be identified when using optimal method conditions. The optimized HILIC method was used to measure the heteroatom make up of a set of aviation turbine fuels; the subsequent data was then subjected to a rigorous statistical analysis using multiple techniques. Statistical analysis tools including principal component analysis (PCA) and fold change (FC) analysis offer a look inside the chemically complex composition of (open full item for complete abstract)

Doctor of Philosophy, Case Western Reserve University, 2025, Chemical Engineering

Direct air capture (DAC) of CO2 is a keystone technology in global plans to mitigate climate change. While the existing materials capable of performing this difficult separation can absorb high amounts of CO2 from air, the heat required to regenerate them for reuse imposes an immense energy tax. With projected energy demands for DAC exceeding 120 petajoules per year by 2030 (nearly the total annual electricity consumption of Ireland), more efficient materials and processes are vital to reaching net zero CO2 emissions. Ionic liquids (ILs) – salts that melt below 100 ˚C – are a class of solvents with exceptional tunability and negligible volatility, making them excellent candidate materials for DAC. However, a major barrier to the implementation of ILs in DAC is their high viscosity, limiting the diffusion rate of CO2. Through fundamental property characterization, spectroscopic investigation, and lab-scale performance analysis, this thesis seeks to build the scientific foundation for leveraging the advantages of ILs while mitigating their weaknesses by creating composite materials with ILs, enabling high performance DAC sorbents that can be regenerated using dielectric heating (the same heating mechanism as a kitchen microwave). We first explore the complex role that hydrogen bonding plays in CO2 binding mechanisms when diluting amino acid ILs with ethylene glycol to lower their viscosity. We reveal through collaborative study with computational chemists that hydrogen bonding can limit the interactions between amine binding sites, preventing their deactivation and resulting in maintained gravimetric capacity upon dilution. Next, we demonstrate the first successful regeneration of an IL by microwave irradiation. We reveal through finite element modeling that experimental trends in heating rate when varying frequency and material are highly dependent on the geometry of the system. Finally, we investigate the formation of composites between an IL and a metal organic (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Oil and gas transmission pipelines are frequently prone to internal corrosion in field environments. Use of organic corrosion inhibitors is an economical and effective way to combat this problem. Their typically amphiphilic inhibitor molecules provide protection by adsorption on the metal surface. Therefore, understanding and quantifying adsorption phenomena has significance for prediction of corrosion inhibition performance of a particular compound. In this dissertation research, a quartz crystal microbalance with dissipation monitoring (QCM-D) was the primary tool used to investigate the adsorption of two corrosion inhibitor model compounds on a noble gold substrate. The research reported herein shows how QCM-D can be used effectively to gain insights about the properties of the adsorbed layer, quantify adsorption/desorption kinetics, make predictions on the possible adsorbed layer configurations, and investigate the influence of inhibitor molecular structure on adsorption phenomena. Since real scenarios involve an actively corroding substrate, a classical oscillatory circuit-based quartz crystal microbalance (QCM) was also used to probe the metal-solution interface for a corroding and corrosion product forming experimental system; this facilitated deciphering the various reaction steps involved. The QCM-D findings in the present research indicate that the geometric surface coverage was less than 100% even for inhibitor concentrations above the surface saturation concentrations. This can help in answering a historical question in corrosion inhibition research about non-zero corrosion rates at inhibitor concentrations corresponding to maximum inhibition. Furthermore, the kinetic adsorption/desorption constants were estimated from the adsorption curves and verified successfully by predicting desorption behavior. This is of great significance, as this methodology can be further extended to study corrosion inhibition and its persistency. Furthermore, this serves as (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Carbon steel pipelines in the oil and gas industry are susceptible to corrosion due to their exposure to corrosive gases like carbon dioxide (CO2) dissolved in the reservoir brine. These pipelines typically carry a mixture of oil, water, and gas phases. The oil phase does not cause corrosion – only the wetting of the pipe surface by water does. However, the alternating wetting of the pipeline surface by oil and water, known as "oil/water intermittent wetting", can influence the corrosion mechanisms and make the surface more resistant to corrosion even if it returns to a fully water wet state. Although extensive research has been conducted on CO2 corrosion in water-only environments, the role of the oil phase has often been far less investigated. Existing literature on the effects of oil are limited to flow patterns and phase wetting studies, with no direct correlation to corrosion rates. This study aims to develop an experimental apparatus and methodology that simulates oil/water intermittent wetting and investigate its effect on uniform and localized CO2 corrosion behavior of carbon steel. A wide range of experimental conditions, including different types of model oils containing surface-active compounds with varying concentrations, different pH values, flow velocities, elevated temperatures, and longer exposure time to oil/water intermittent wetting, were tested.

Doctor of Philosophy, University of Akron, 2024, Integrated Bioscience

Corrosion in natural gas transmission pipelines poses significant risks to infrastructure integrity, leading to environmental damage and economic loss. This dissertation investigates microbiologically influenced corrosion (MIC) mechanisms and develops detection methods using split-chamber zero-resistance ammetry (SC-ZRA). Microbial cultures were enriched from natural gas pipeline samples, focusing on fermentative and sulfur-metabolizing bacteria, and their corrosion activities were evaluated using SC-ZRA. Chapter I reviewed the threat corrosion posed to carbon steel pipelines transporting oil and natural gas, emphasizing MIC's role. It described the electrochemical nature of corrosion and explained how microorganisms like sulfate-reducing and fermentative bacteria accelerated the process through biofilm formation, production of corrosive metabolites, and disruption of electrochemical balance. The chapter also highlighted electrochemical techniques, particularly SC-ZRA, used to detect and monitor MIC. ZRA allowed real-time observation of corrosion currents and distinguished between biotic and abiotic corrosion activities. Chapter II demonstrated that organic acid production by fermentative bacteria lowered pH, accelerating corrosion through cathodic hydrogen reduction on carbon steel. When buffered with sodium bicarbonate, acidity was reduced, effectively mitigating corrosion. Chapter III explored sulfur-metabolizing bacteria's role in corrosion. Experiments with thiosulfate and thiols showed that these bacteria, particularly Desulfovibrio alaskensis, produced sulfide, promoting corrosion. SC-ZRA measurements highlighted how cysteine degradation and thiosulfate reduction drove electron transfer, leading to metal oxidation. Metagenomic analysis confirmed the presence of genes responsible for sulfate and thiosulfate reduction and hydrogenase activity, indicating that diverse metabolic pathways contributed to corrosion. Chapter IV discussed the integration of microbiol (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Molecular dynamics simulations and enhanced sampling techniques were employed to investigate adsorption behavior of surfactants at aqueous (metal-water and oil-water) interfaces. Key findings include: (a) Surfactants exhibit a strong affinity for metallic nanoparticles (MNPs), with a tendency of the alkyl tails to wrap around the MNPs. (b) The polar head of surfactants preferentially adsorbs onto the low-coordinated sites on MNPs, while the surfactant tails show no significant preference to adsorb on different MNP facets. (c) Surfactants with longer tails have a higher tendency to aggregate with themselves upon adsorption onto MNPs. (d) On a partially surfactant-covered planar metal-water interfaces, surfactant micelles preferentially adsorb onto bare metal patches. In contrast, on a fully surfactant-covered metal surface, adsorption is primarily driven by hydrophobic interactions, leading to the formation of a hemispherical configuration. (e) Surfactant micelles encounter a free energy barrier to adsorption on metal surfaces, regardless of the extent of surface coverage. (f) At oil-water interfaces with linear oil molecules, surfactants aggregate at the interface along with the oil molecules that align parallel to the orientation of the surfactants' alkyl tail. (g) In the presence of aromatic oil, linear surfactants and linear oils do not form a structured interface layer. (h) The interfacial tension at the oil-water interface decreases with increasing surfactant concentration.

Doctor of Philosophy, The Ohio State University, 2024, Chemical Engineering

Hemoglobin (Hb) is the protein responsible for the transports of oxygen within the human body, made up of two α- and two β-globins each with a heme porphyrin group containing an iron center. Diseases related to Hb are caused by genetic disorders that either change the globin formation or rate of globin production. Sickle cell disease (SCD) is one such Hb related genetic disorder that affects millions around the world with approximately 100,000 in the United States. Sickle Hb polymerizes under deoxygenated conditions and stretch the red blood cell (RBC) membrane, leading to hemolysis and the release of Hb into the extracellular space. Once Hb is outside of the RBC, it initiates multiple downstream toxicity pathways. Hb, heme, and iron all exhibit toxicity when outside of the RBC and leads to vasoconstriction, inflammation, tissue, and organ damage. The scavenger proteins haptoglobin, hemopexin, and transferrin, are acute phase proteins that bind to and remove from circulation Hb, heme, and iron, respectively, thus preventing the toxic downstream effects. For SCD patients, these proteins are chronically depleted. In this work, we propose the development of a protein therapeutic for the removal of Hb, heme, and iron with haptoglobin, hemopexin, and transferrin using tangential flow filtration and chromatographic techniques.

Doctor of Philosophy, The Ohio State University, 2024, Chemical Engineering

The global impact of human activities on Earth's biophysical processes and resources is of significant concern. Concurrently, ambitious global objectives such as 'Nature-Positive by 2030' and 'Net-Zero CO2 by 2050' have been proposed and widely embraced as guiding principles for future development. These ambitious goals highlight the urgent need to cultivate a harmonious relationship between human endeavors and nature, acknowledging the inherent connection between environmental well-being and the sustainability of our economic and social systems. To achieve these global goals, the role of nature should be incorporated into sustainability assessment and system design. This dissertation focuses on developing science-based methods and framework to assess the absolute environmental sustainability and design absolute sustainable of chemical process system. Nature's carrying capacity, quantified by biophysical models and geographical data, is used as an absolute reference value in this science-based method. Compared to current absolute environmental sustainability assessment (AESA) method based on Planetary Boundary framework, this science-based AESA method is more robust, has high geographical resolution and encourages sustainability actions towards the 'Nature-Positive' goal. Through case studies on chemical products in their major supplying countries, we illustrate existing regional and global sustainability issues, also propose promising nature-based solutions for decarbonization to achieve 'Net-Zero' emission. An user-friendly open-source software and an ecological inventory database have been developed. This software assists stakeholders with diverse backgrounds in decision making on absolute environmental sustainability purpose. For absolute sustainable system design, a multiobjective mixed-integer linear programming model is developed for designing a supply chain under the ecological safe and socially just operating space. This model covers the life cycle scale of (open full item for complete abstract)

Master of Science in Engineering, Youngstown State University, 2024, Department of Civil/Environmental and Chemical Engineering

Wearable biosensors have become a valuable tool for their promising applications in personalized medicine. Cortisol is a biomarker for various diseases and plays a key role in metabolism, blood pressure regulation, and glucose levels. In this study, we fabricated an interdigitated laser-induced graphene (LIG) biosensor for the non-faradaic impedimetric detection of cortisol in sweat. A direct laser writing technique was used to produce the LIG. Gold nanoparticles (AuNPs) were electrochemically deposited onto the surface to enhance impedance response. A Self-Assembled Monolayer (SAM) was formed with on the AuNPs via 3-Mercaptopropionic acid (MPA) thiol chemistry. The carboxylic acid (-COOH) groups of the MPA were activated using EDC/NHS chemistry. Following activation, anti-cortisol antibodies were immobilized on the surface. Lastly, the LIG was incubated in the blocking agent bovine serum albumin (BSA) to avoid unwanted detection. Surface characterization of the LIG was performed at each step of modification by Electrochemical impedance spectroscopy (EIS) in a phosphate buffered saline (PBS) solution containing a 5 mM Fe(CN)3-/4- (1:1) redox couple. Further characterization of the modified LIG electrode was achieved through Fourier transform infrared (FT-IR), surfaced-enhanced Raman spectroscopy (SERS), and X-ray diffraction (XRD). The detection experiment using EIS was conducted in increasing concentrations of cortisol (0.1 pM-100 nM) in PBS. The ZMod decreased logarithmically (R2=0.97) with a 0.0085 nM limit of detection. Reproducibility was examined by percent change of ZMod at 100 nM and a 5.93%RSD (n=5) was observed. Additional analysis of sensor specificity and interference studies showed no substantial effect on detection. This research establishes the feasibility of using the gold nanoparticle decorated LIG electrode for flexible, wearable cortisol sensing devices, which would pave the way towards an end-user easy-to-handle biosensors as point-of-care diagno (open full item for complete abstract)

Master of Science in Engineering, Youngstown State University, 2024, Department of Civil/Environmental and Chemical Engineering

A longitudinal study in corrosion was performed on tensile-elongation dog-bones, created using 3D-printed stainless steel. The effects of exposure to an acidic environment were investigated regarding mass-loss, tensile and yield strength, modulus of elasticity, profilometry of pits and defects, and microscopy of fracture-sites. The SS316L specimens were manufactured using different print-directions, specifically overlapping unidirectional or rotated bidirectional for each layer by an additive manufacturing unit, the Mazak VC-500/5X AM HWD. The novel aspect of this research is focusing on the differences that the path the hot-wire, direct energy deposition, print-head has on its corrosion characteristics, as opposed to only focusing on the printing-parameters. The goal was to determine what printing-directions and methods were best for resisting corrosion. The research outlines the process of preparing samples for controlled weight-loss in HCl as well as the methods used to measure the mechanical properties. This allows for the results to be repeated if desired. Upon thoroughly reviewing the data and drawing connections where applicable, it was determined within the test samples that unidirectional print-directions yielded better mass-loss and mechanical attributes than bidirectional printing. It was found that some print directions, namely 90°, which is perpendicular to the printing door, performed notably better than other directions such as 0° or 45°.

Doctor of Philosophy (PhD), Ohio University, 2024, Civil Engineering (Engineering and Technology)

Colloidal aggregation is a critical phenomenon influencing various environmental processes. However, limited research has been conducted on the aggregation of particles with heterogeneous physical and chemical properties, which are more representative of practical environmental systems than homogeneous particles. The central hypothesis of this dissertation is that primary particle size polydispersity along with chemical and material heterogeneity of primary particles exert non-trivial effects on the aggregate growth rate and the fractal dimensions of aggregates. In this dissertation, the aggregation and stability of heterogeneous nano- and sub-micrometer particles in aqueous systems were investigated using in situ microscopy and image analysis. Initially, the study examined the growth kinetics and structures of aggregates formed by polystyrene microplastics in mono- and bidisperse systems. Findings indicated that while the primary particle size distribution did not affect the scaling behavior of aggregate growth, it delayed the onset of rapid aggregation. Structural analysis revealed a power law dependence of the aggregate fractal dimension in both mono- and bidisperse systems, with mean fractal dimensions consistent with aggregates from diffusion-limited cluster aggregation. The results also suggested that aggregate fractal dimension was insensitive to shape anisotropy. The dissertation further explored the structure of DLCA aggregates in heterogeneous systems composed of particles with varying sizes, surface charges, and material compositions. The fractal dimensions of DLCA aggregates in these heterogeneous particle systems were similar, ranging from 1.6 to 1.7, and consistent with theoretical predictions and experimental evidence for homogeneous DLCA aggregates. This confirmed the universality of aggregate structures in the DLCA regime, regardless of particle composition. Additionally, a scaling relationship was demonstrated between aggregat (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2024, Polymer Science

Polyethylene (PE) and isotactic polypropylene (iPP) are the two most abundant commodity plastics. However, these materials are incompatible in the melt blend due to the different surface energies owing to the difference in their microstructures. The transfer of stress between incompatible phases of these polymers is a challenge that contributes to mechanical recycling process losses. This prevents the mixed mechanical recycling of these polymers to yield commodity plastics for high performance applications compared to the virgin resins. As a result, there is a lack of incentive to recycle mixed plastic waste, thereby contributing to plastic pollution in the environment. Compatibilizer additives improve the performance of these blends, through non-covalent, supramolecular, and covalent interactions across PE/PP interfaces. By introducing a small amount of compatibilizer into recycled polyolefin blends, there is potential to enhance the properties, reduce waste plastic, and achieve these in economical fashions. This work investigates several methods of delivering copolymer reinforcing agents which include supramolecular coupling through diverse architectures, namely diblock structures that are proposed to form in-situ and preformed multiblock architecture. The first part of this work will highlight the synthesis of a compatibilizer system consisting of end-functionalized iPP and HDPE. These materials are referred to as Interfacial Supramolecular Coupling Agents (ISCAs) due to their proposed ability to form supramolecular H-bonds across the bulk PE/PP interfaces. The synthesis of high melting-temperature iPP with controlled molecular weight and end-group fidelity is described. Through a sequence of reactions, vinyl end-functionalized iPPs and PEs are converted to β-alanine trimer terminated polyolefins, which are being studied as potential compatibilizers for PE/PP blends. A second strategy describes the use of pre-synthesized multiblock compatibilizers which have hi (open full item for complete abstract)