Engineering Commons^™

Improving Degree Of Delignification And Selectivity Of Oxygen Delignification Of Southern Pine Kraft Pulp, Azadeh Pahlevanzadeh

Electronic Theses and Dissertations

Oxygen delignification is a pre-bleaching stage that provides environmental benefits for bleached pulp production by replacing about 50% of the chlorine-based bleaching chemicals with oxygen. The resulting reduction in chlorine-based chemicals leads to a significantly lower release of chlorinated organics in the pulp bleaching effluent. However, the main disadvantage of applying oxygen delignification is the low delignification/cellulose degradation selectivity compared to chlorine dioxide bleaching. Modern conventional oxygen delignification is limited at level 60% delignification to maintain an acceptable cellulose Degree of Polymerization (DP) and thus fiber strength as indicated by the pulp intrinsic viscosity. The increase in the degree of …

Catalytic Ring Opening Of Mono- And Bicyclic Compounds For The Production Of Renewable Diesel And Jet Fuel, Matthew J. Kline

Electronic Theses and Dissertations

Thermal DeOxygenation (TDO) is a process that converts organic acids produced from cellulose hydrolysis and dehydration into a low-oxygen bio-oil containing substituted naphthene compounds. The high aromatic content is desirable for gasoline fractions, but middle distillates such as diesel and jet fuel require upgrading via hydrogenation and ring opening to achieve better combustion characteristics. Previous research has demonstrated that TDO oil could be hydrogenated over high-surface-area nickel catalysts to improve the combustion characteristics, but the cetane number was still below the specifications.

Multiple supported catalysts were synthesized by ion exchange and incipient wetness impregnation, and the catalysts were characterized by …

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, …

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 …

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 …

Charged-Particle Interactions To Generate Novel Coatings And Materials, Pradnya D. Rao

Electronic Theses and Dissertations

A typical paper coating formulation contains anionically charged pigments and latex to provide a high-quality surface for printing. However, during application and drying, the latex can migrate to the surface or deep into the paper, resulting in weak coating layers or the need to use a high latex content to obtain the same strength properties. In this thesis, we have explored the introduction of cationically charged particles into the suspension as a way to reduce the amount of binder in the coatings, improve coating strength and reduce binder migration. With these aims in mind, we have generated cationic precipitated calcium …

Highway Stormwater Runoff On-Site Treatment Using Bioslope With New Media Of Biochar Amended Topsoils, Ahmed I. Yunus

Electronic Theses and Dissertations

Georgia Department of Transportation (GDOT) has constructed various treatment facilities on its right-of-way (ROW) to collect and treat highway stormwater runoff, emphasizing total suspended solids (TSS) removal. The permit performance goal set by the Georgia Environmental Protection Division (EPD) is 80% TSS removal. Current stormwater best management practice (BMP) treatment facilities include complex and permanent infrastructures such as bioslope, bioretention basins, sand filters, infiltration trenches, and grass channels. Among these BMPs, bioslope has been becoming more popular due to its applicability for roadway embankments and areas with limited ROW constraints. It removes pollutants effectively by physical filtration and chemical adsorption …

A Computational Fluid Dynamics Analysis Of The Temperature And Impurity Profiles In The Protodune-Sp Neutrino Detector, Jenna Harrison

Electronic Theses and Dissertations

Computational fluid dynamics (CFD) models of the ProtoDUNE single-phase detector were developed, refined, and analyzed. The ProtoDUNE single-phase detector is a prototype detector that is part of the Deep Underground Neutrino Experiment, an international research collaboration aimed at better understanding neutrinos and the role they play in our universe. The ProtoDUNE single-phase detector is used to gather data and inform design changes for the full-sized far detector prior to its construction. The effects of certain geometric features and heat sources on the thermal profiles within the liquid region of the detector were investigated in a set of parametric studies. The …

Real-Time Monitoring Of Cell Death Progress Using Capacitance Spectroscopy, Suyang Wu

Electronic Theses and Dissertations

Biologics, including the monoclonal antibody (mAb), has experienced rapid development in the last decade. However, the price of biologics is often prohibitively high because of the low process efficiency. Delaying the inevitable cell death improves the productivity of upstream bioprocessing, whose success relies on monitoring the cell death onset that indicates the timing for preventive actions.

This study proposes to develop a real-time monitoring model that quantifies the dying cell percentage in lab-scale bioreactors using capacitance spectroscopy. The capacitance spectroscopy contains cell death-related information due to various physical properties changes during the cell death process, e.g., cytoplasmic conductivity change. The …

Techno-Economics And Life Cycle Analysis Of Upgrading Woody Biomass To Diesel Blendstock, Aysan Najd Mazhar

Electronic Theses and Dissertations

Woody biomass conversion to transportation fuels have been developed as alternatives to fossil fuel production to reduce greenhouse gas emissions and to increase energy security. Fast pyrolysis, a thermochemical technology, has the potential to offer high efficiencies to produce liquid transportation fuels from woody biomass. Fast pyrolysis involves rapid heating of biomass particles in the absence of air at approximately 500°C and results in non-condensable gases, bio-oil (pyrolysis oil), and char as products. The pyrolysis oil can be upgraded via integrated mild hydrogenation and etherification processes to a high energy density fuel that can be blended with diesel for transportation …

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 …

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, …

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 …

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 …

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 …

Optimization Of Chemical Compositions Of Al-Si-Cu-Ni-Sr Alloys With High Strengths And Electrical Conductivities, Yuxian Li

Electronic Theses and Dissertations

Mechanical strengths and electrical conductivity are the very important engineering properties of lightweight metallic materials used in the automotive industry, especially for battery-powered electric vehicles (BEV). However, the main issue is that high strength and high electrical conductivity are mutually exclusive due to physical nature of these properties. The aim of this study is to develop new cast aluminum alloys for the production of rotor bar in the rotor with high as-cast strength and electrical conductivity. A design of experiment (DOE) technique, Taguchi method, was used to develop high as-cast strength and electrical conductivity alloys with various element addition of …

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 …

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 …

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 …

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 …

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 …

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 …

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” …

Annealing Of Encapsulated Heavy Metals From Brine Water Utilizing Microwave Enabled Sol-Gel Process, Adam Michael Flynn

Electronic Theses and Dissertations

Various waste encapsulation strategies have been investigated to solidify and stabilize heavy metal wastewater for proper long-term storage. This work aims to enhance a method of novel sol-gel encapsulation of heavy metals from mock brine waters using tetramethyl orthosilicate with the addition of an annealing step at various temperatures in order to reduce leaching of metals from the silica monoliths when exposed to water. The metals tested for encapsulation and leaching were mercury (II) chloride, potassium dichromate, sodium selenite, boric acid, cadmium chloride, and copper (II) acetate. The annealing of the silica monoliths led to an increased degree of for …

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 …

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 …

Surface And Interfacial Phenomena Between Soil And Oil, Md Firoz Ahmed

Electronic Theses and Dissertations

Crude oil and motor oil spills on land have severe environmental consequences that pose threats to both humans and natural resources. It is particularly important to know the flow behavior of oils to protect terrestrial ecosystems from this kind of damage. The spreading kinetics, contact angle (CA), and droplet baseline studies of crude oil and motor oils were investigated over several realistic soil-based matrices composed of topsoil (silt-dominant), sand, clay, and moisture. It was found that with an increase in moisture content (MC), the spreading area decreased, and initial spreading time increased for all given oil. The initial CA generally …