Master of Science (MS), Ohio University, 2016, Mechanical Engineering (Engineering and Technology)

The aim of this work was to investigate the use of a catalytic material to accelerate the formation of carbonic acid in a thin liquid film using a vertical membrane mass transfer system. Results comparing the rate of formation of Total Inorganic Carbon (TIC) for similar experimental conditions between the non-catalytic and the catalytic mass transfer systems indicated a statistically significant increase in carbonic acid formation with catalytic mass transfer system. The increased rate of TIC accumulation in the media indicated that the catalytic galvanized mesh potentially accelerated the rate limiting step, i.e. the formation of carbonic acid on the thin liquid film.

Committee: David Bayless Ph.D., P.E., Fellow of ASME and NAI (Advisor); Gregory Kremer Ph.D. (Committee Member); Frank Kraft Ph.D. (Committee Member); Morgan Vis-Chiasson Ph.D. (Committee Member) Subjects: Chemical Engineering; Chemistry; Energy; Engineering; Environmental Engineering; Mechanical Engineering

PHD, Kent State University, 2021, College of Arts and Sciences / Department of Chemistry and Biochemistry

Porous carbons are promising candidates for CO2 adsorption because of high surface area, good thermal and chemical stability, easy regeneration, widely available precursors, and ability of tailoring their porous structure and surface chemistry. High CO2 adsorption capacity under atmospheric conditions is primarily governed by the volume of micropores below 1 nm. Therefore, the post-synthesis chemical or physical activations of carbons are usually applied to enhance microporosity. This process usually involves harsh chemicals (e.g., KOH and ZnCl2) and high activation temperature. In addition, the presence of mesopores (2-50 nm) is also beneficial for CO2 capture because these pores facilitate CO2 diffusion. Thus, carbons that possess a high fraction of small micropores and suitable amount of mesopores would be ideal materials for high CO2 uptake. Phenolic resins (PRs) produced by polymerization between phenolic compounds and formaldehyde are often used carbon precursors for the synthesis of mesoporous carbons due to easy preparation. Although they are convenient precursors, PRs are highly toxic and expensive. Biomass gains a lot of attention as an alternative carbon source in economic and environmentally friendly production of carbons. However, the biomass derived carbons often have irregular porous structure and low surface area. Therefore, it is very challenging to find an effective synthesis strategy to obtain carbons with tailored porosity from diverse biomass sources. The goal of this dissertation was to develop the facile and eco-friendly synthesis routes for the preparation of micro-mesoporous carbons for superior CO2 uptake. The synthesis was designed based on green chemistry requirements, which includes the use of renewable feedstock and less toxic reagents for the carbon preparation. Porous carbons reported in this dissertation were prepared from condensed tannins, which are natural phenolic compounds, instead of synthetic phenolic compounds as carbon precu (open full item for complete abstract)

Committee: Jaroniec Mietek (Advisor); Huang Songping (Committee Member); Shen Hao (Committee Member); Portman John (Committee Member); Almasan Carmen (Committee Chair) Subjects: Chemistry; Materials Science; Nanotechnology; Physical Chemistry

MS, University of Cincinnati, 0, Engineering and Applied Science: Environmental Science

An innovative method of recovering carbon dioxide from flue gas has been studied whereby reclaimed magnesium hydroxide is used as the scrubbing agent. A slurry of magnesium hydroxide (Mg(OH)2) was used to separate carbon dioxide (CO2) from flue gas in an absorber. Thermodynamic equilibrium calculations indicate that by scrubbing flue gas already cleaned of its sulfur dioxide (SO2) concentration, 99% of the CO2will react to form more soluble magnesite (MgCO3) and hydromagnesite ((Mg4(CO3)3(OH)2) in the scrubber, and that CO2 will be released when the resulting solution is heated. Turbine waste heat can be used to heat the CO2-laden slurry, creating a rich stream of CO2 gas for further processing. The Mg(OH)2 slurry can then be recycled for further CO2 absorption.

This project established proof of concept of this model by studying the reaction characteristics of the absorption of CO2 by solutions containing Mg(OH)2 in a bench-scale bubble column operated under realistic conditions. An NDIR analyzer measured the CO2 concentration in the exit gas. From this data, the steady state reaction characteristics have been determined using a simulated flue gas of 5%, 10%, and 20% CO2, Mg(OH)2 slurry concentrations of 0.027, 0.068, and 0.14 moles per liter at temperatures of 25, 45, and 65oC. Both commercially available Mg(OH)2 and reclaimed Mg(OH)2 were used. Finally, the mass transfer coefficient K'AG was calculated for the system.

Committee: Timothy Keener Ph.D. (Committee Chair); Sumana Udom Keener Ph.D. (Committee Member); Soon Jai Khang Ph.D. (Committee Member) Subjects: Environmental Science

Doctor of Philosophy, The Ohio State University, 2013, Chemical and Biomolecular Engineering

Hydrogen is produced in large scale by steam reforming followed by water-gas-shift reaction, which yields a product stream consisting mainly of H2 and CO2. Purification of H2 from other gaseous compounds, mainly CO2, with significantly improved energy and cost efficiencies therefore becomes a crucial step for hydrogen economy that could ultimately provide hydrogen as a clean, renewable fuel as well as versatile chemical with wide commercial uses, reduce the reliance of modern industries on petroleum, and restrain global greenhouse gas emissions. Facilitated transport membranes are well suited for CO2/H2 separation due to high selectivity accompanied with high CO2 permeability, H2 product recovery at high pressure, and low energy and cost consumptions. The objective of this research is to develop advanced CO2-selective facilitated transport membranes with desired properties for practical gas separation applications. Novel facilitated transport membranes have been synthesized by incorporating sterically hindered amines as CO2 carriers in crosslinked polyvinylalcohol networks. The membrane has shown high, stable performance in terms of CO2 permeability (about 3719 Barrers) and CO2 selectivities vs. H2 (about 319) and N2 (about 677) for a period of at least 430 hours at 110 Degree Celsius and typical fuel cell operating pressure of 2 atm. Facilitated transport membranes with ultrathin separation layers (less than 2 micrometers) were also synthesized and exhibited promising selectivity and permeance for CO2 capture from flue gas. An average CO2 permeance of 726 GPU with CO2/N2 selectivity of 162 at 1 atm and 102 Degree Celsius has been achieved. This research further exploited the superlative mechanical property of multi-walled carbon nanotubes (MWNTs) to reinforce the mechanical strength of amine facilitated transport membranes and successfully developed durable nanostructured polymer-MWNT membranes by incorporating MWNTs into the crosslinked poly (open full item for complete abstract)

Committee: W.S. Winston Ho (Advisor); L. James Lee (Committee Member); Shang-Tian Yang (Committee Member); Rachel G. Kleit (Committee Member) Subjects: Chemical Engineering

PhD, University of Cincinnati, 2009, Engineering : Chemical Engineering

Global warming is unequivocal due to greenhouse effect, majorly caused by increasing concentration of carbon dioxide in the atmosphere. Using metal oxide sorbents, such as calcium oxide, is one of the most potent ways to separate CO2 in contrast to existing or emerging technologies today. Unlike other technologies, calcium-based separation can be applied easily above 550 °C for capturing CO2.Calcium-based sorbents were prepared first using inorganic and organometallic precursors (OMP) by calcination or wet chemistry. Sorbent performance was tested using a thermogravimetric analyzer (TGA). Amongst all, the sorbents prepared from calcium propionate and calcium acetate exhibited the highest capacity to uptake CO2, converting from calcium oxide to calcium carbonate. These two sorbents possessed higher BET surface area and larger pore volume than the other sorbents. Thermal decomposition of these two OMPs resulted in the maximum evolution of heat, which could eventually lead to the generation of larger macropores, thus explaining the resultant CO2 uptake capacity demonstrated. The sorbents originated from OMPs and involved more heat during formation of calcium carbonate exhibited better performance. Therefore, flame technique, which involves with combustion of OMPs, was applied to synthesis sorbents. Scalable flame spray pyrolysis (FSP) is unique in making controllable sized nanoparticles. Such flame-made sorbents consisted of nanostructured calcium oxide and calcium carbonate with high specific surface area (40-90 m2/g), exhibiting faster and higher CO2 uptake capacity than non FSP-made sorbents. In multiple carbonation/decarbonation cycles, the nanostructured sorbents demonstrated relatively stable, reversible and high CO2 uptake capacity sustaining molar conversion at about 50% after 60 such cycles,. The high performance of flame-made sorbents is best attributed to their nanostructure (30-50 nm grain size) that allows operation in the reaction-controlled carbonation (open full item for complete abstract)

Committee: Panagiotis Smirniotis PhD (Committee Chair); Yuen-Koh Kao PhD (Committee Member); Jerry Lin PhD (Committee Member); Neville Pinto PhD (Committee Member); Sotiris Pratsinis PhD (Committee Member) Subjects: Chemical Engineering; Energy; Environmental Engineering

Doctor of Philosophy, Case Western Reserve University, 2009, Chemical Engineering

This work describes an investigation of CO-CO2 exchange on 40 mol% gadolinia-doped ceria (GDC) electrodes for potential application as a CO2 reduction cathode for the solid oxide electrolysis of CO2.A computational analysis was performed on the thick electrolyte cylindrical pellet test cell geometry to investigate the effects of this cell geometry on Electrochemical Impedance Spectroscopy (EIS) due to non-linear current distribution. The analysis showed the particular cell geometry selected does induce an error of 15% on the impedance measurements, but in a predicable linear manner. Additional parametric analyses indicate that impedance errors for the cylindrical cell geometry can be reduced by covering the faces of the pellet with the working and counter-electrodes, centering the reference electrode hole equidistant from working and counter-electrodes, or utilizing a reference electrode mounted at the midpoint edge of the pellet. A continuum-based model is described for equilibrium CO-CO2 exchange on a mixed-conducting electrode utilizing porous electrode theory. The resulting three-parameter model is expressed in terms of a characteristic resistance, a characteristic time constant, and a utilization thickness ratio, that can be related to physiochemical properties. EIS measurements were performed on the 40 mol% GDC electrodes on yttria stabilized zirconia (YSZ) electrolytes at 700-950 degrees C in reducing CO/CO2 atmospheres. Area-specific-resistance (ASR) values for this electrode were in the range of 0.8-37 ohm-cm2, about two orders of magnitude lower than measurements on Pt electrodes and slightly lower than data on Ni-YSZ electrodes in the literature under similar temperature and partial pressure of oxygen conditions. An analysis utilizing the continuum-based porous electrode model was performed to extract the vacancy diffusion coefficient and surface exchange rate coefficient as a function of temperature and partial pressure of oxygen, from the impedance res (open full item for complete abstract)

Committee: Chung-Chiun Liu PhD (Advisor); Stuart B. Adler PhD (Committee Member); Uziel Landau PhD (Committee Member); Mark R. DeGuire PhD (Committee Member); J. Adin Mann PhD (Committee Member) Subjects: Chemical Engineering; Chemistry; Materials Science

Master of Science, The Ohio State University, 1972, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy (PhD), Ohio University, 2023, Chemical Engineering (Engineering and Technology)

Internal corrosion of transmission tubulars is a huge concern in the oil and gas industry. Corrosion inhibitors (CIs) are often considered the first step in mitigating internal corrosion due to their high efficiency and cost-effectiveness. Yet, predicting the efficiency of corrosion inhibitors, developed and tested in a laboratory environment, in operating field conditions is very challenging. In addition, the presence of corrosion residues or corrosion products on the internal surface of tubular steels can significantly affect the inhibition performance of organic corrosion inhibitors. This aspect is only rarely considered when characterizing the performance of corrosion inhibitors. Therefore, understanding their effects on corrosion inhibition is of great benefit in applying corrosion inhibitors to tackle internal corrosion issues, particularly in aging pipelines. This work mainly focuses on evaluating the corrosion inhibition and revealing the inhibition mechanisms in the absence and presence of various corrosion residues or products, commonly found in oil and gas production. The first half of this work (Chapter 5 and 6) presents a methodology for the characterization of corrosion inhibitors and proposes several innovations to an inhibition prediction model, originally based on the work of Dominguez, et al.. An inhibitor model compound, i.e., tetradecyl phosphate ester (PE-C14), was synthesized in-house and characterized to obtain necessary parameter values required as inputs for the inhibition model. The updated inhibition model could predict steady state and transient corrosion inhibition behaviors with good accuracy. The second half of the presented work (Chapter 7, 8, and 9) focuses on the effects of corrosion residue (Fe3C) and products (FeCO3 and FeS) on corrosion inhibition and advances the understanding of the associated inhibition mechanisms. The galvanic effect caused by residual Fe3C on corrosion rate and inhibition efficiency was quantitatively (open full item for complete abstract)

Committee: Marc Singer (Advisor); Srdjan Nesic (Committee Member); David Young (Committee Member); Sumit Sharma (Committee Member); Katherine Cimatu (Committee Member); Katherine Fornash (Committee Member) Subjects: Chemical Engineering; Engineering; Materials Science

Doctor of Philosophy, The Ohio State University, 2020, Chemical Engineering

Carbon dioxide (CO2) is an important greenhouse gas that contributes to global warming. To combat the rising emissions of CO2 into the atmosphere, scientists and researchers have devised several methods of carbon capture and storage (CCS), including the use of membranes to trap CO2 molecules, valves to condense CO2 from a mixture of gases, etc. Supersonic separation is a novel method of gas-gas separation that has been used to separate natural gas from other gases. It has been suggested for and is being currently studied as a method for the removal of CO2 from flue gas before it enters the atmosphere. Supersonic separation relies on the condensation of CO2 clusters into particles large enough to be inertially separated, requiring a size of approximately 1 micrometer in diameter. In order to effectively design hardware to capture CO2 using this mechanism, we need to study and collect fundamental nucleation properties of CO2 and quantify the process under supersonic flow conditions. To this end, we studied the condensation of CO2 in two supersonic nozzles of differing expansion rates, T1 and T3, and sought to quantify the onset of nucleation, particle size distributions, and aerosol number densities. First, we confirmed that homogeneous nucleation of CO2 could not take place in nozzle T1 when expansions started from a stagnation temperature of 20°C, no heat release was observed in pressure trace measurements at 7.0 to 11 mol% CO2. Lowering the stagnation temperature to 10°C showed some evidence of heat release, but it was uncertain to what extent that was due to condensation of particles or whether the nozzle overexpansion had caused a shock to increase the temperature and pressure of the flow. Analysis of the saturation curve suggests the nucleation event was incomplete, and lower temperatures were required for a full characterization. Second, we performed a series of pressure trace measurements (PTM) in nozzle T3 for concentrations of CO2 in Ar ranging from 0.5 (open full item for complete abstract)

Committee: Barbara Wyslouzil (Advisor); Nicholas Brunelli (Committee Member); Isamu Kusaka (Committee Member) Subjects: Chemical Engineering

Master of Science (MS), Ohio University, 2019, Mechanical and Systems Engineering (Engineering and Technology)

The aim of this study was to enhance a vertical rotating membrane system that induced gas to liquid mass transfer, and to evaluate its performance by quantifying its inorganic carbon formation rate under different parameters such as carbon dioxide concentration in air, membrane's rotational speed and the composition of the liquid medium. In addition to that, the ability of the zinc plated and nickel wire meshes to catalyze the hydration reaction of carbon dioxide was tested in this study using a bench scale rotating membrane system. The system was enhanced by replacing the mechanism that rotated the mass transfer membrane mesh by a simpler mechanism which depended on rollers to rotate the membrane mesh. Testing the enhanced system indicated that increasing the carbon dioxide concentration from 1% to 2%, from 1% to 10% and from 2% to 10% increased the system's inorganic carbon formation rate within the ranges of 69%-83%, 385%-521% and 179%-240% respectively. Furthermore, increasing the membrane's rotational speed from 70 rpm to 90 rpm resulted in increasing the inorganic carbon formation rate within a percentage range of 27%-38%. Also, the tests showed that using BG-11 as a test medium instead of DI water increased the inorganic carbon formation rate within a percentage range of 27%-33.3% when testing the rotating membrane system under 1% and 2% carbon dioxide concentrations respectively. Also, an increase of 7% was noticed when BG-11 medium was used as a medium instead of DI water under 10% carbon dioxide concentration in air. Moreover, results showed that using zinc plated and nickel wire meshes had no impact on catalyzing the carbon dioxide hydration reaction.

Committee: David Bayless (Advisor); Gregory Kremer (Committee Member); John Cotton (Committee Member); Sarah Davis (Committee Member) Subjects: Engineering

Master of Science, The Ohio State University, 2019, Chemical Engineering

Most of the hydrogen is produced from natural gas steam reforming process followed by water-gas-shift (WGS) reaction for syngas purification. The produced mixed syngas, consisting of mainly H2 and CO2, needs to be separated to complete the conversion of CO and obtain high purity H2, which can act as a clean, renewable fuel gas for widely commercial uses. Mixed-matrix membrane incorporated nanofillers containing CO2 carriers is one kind of facilitated transport membrane, which shows remarkable transport performance and excellent stability operated under high pressures and high temperature. In the present work, amino-functionalized multi-walled carbon nanotubes (AF-MWNTs) were chosen as the mechanical reinforcing filler to enhance the membrane stability and as the CO2 carrier to facilitate CO2 transport. Variable amounts of AF-MWNTs were incorporated to crosslinked PVA-poly(siloxane)/amine membranes to synthesize the CO2-selective mixed-matrix membranes. The membrane containing 10 wt.% MWNTs demonstrated optimal stable CO2 permeability of 1090 Barrer and CO2/H2 selectivity of 48 for the 100-h test at 1.5 MPa and 107 °C. The primary purpose of this work was to investigate out the effect of AF-MWNTs loading in the mixed-matrix membrane under high pressure in order to obtain the optimal transport performance. Thus, this research was considered to contribute to the syngas purification of industrial interest.

Committee: W.S. Winston Ho (Advisor); Andre Palmer (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, University of Toledo, 2016, Chemical Engineering

Concerns over the effects of anthropogenic carbon dioxide (CO2) emissions from fossil-fuel electric power plants has led to significant efforts in the development of processes for CO2 capture from flue gas. Options under consideration include absorption, adsorption, membrane, and hybrid processes. The US Department of Energy (DOE) has set goals of 90% CO2 capture at 95% purity followed by compression to 140 bar for transport and storage. Ideally, the Levelized Cost of Electricity (LCOE) would increase by no more than 35%. Because of the relatively low CO2 concentration in post-combustion flue gas, most of the reported process configurations for membrane systems have sought to generate affordable CO2 partial pressure driving forces for permeation. Membrane Technology and Research, Inc. (MTR) proposed the use of an air feed sweep system to increase the CO2 concentration in flue gas. This process utilizes a two-stage membrane process in which the feed air to the furnace sweeps the flue gas in the second stage to reduce the flow of CO2 in the effluent to 10% of that leaving the furnace. Such a design significantly reduces capture costs but leads to a detrimental reduction in the oxygen concentration of the feed air to the boiler. In this dissertation, the economic viability of combined cryogenic-membrane separation is evaluated. The work incorporates the tradeoff between CO2/N2 selectivity and CO2 permeability that exists when considering the broad range of potential membrane materials. Of particular interest is the use of lower selectivity, higher permeability materials such as polydimethylsiloxane (PDMS). Additional enriching stages are required in a membrane-cryogenic air feed sweep configuration to enable use of these materials and achieve the 90% CO2 recovery and 95% purity targets. The higher CO2 permeance of PDMS significantly reduces the total module membrane area requirement and associated capital cost (CAPEX). However, the lower selectivity increases th (open full item for complete abstract)

Committee: GLENN LIPSCOMB PhD (Committee Chair); MARIA COLEMAN PhD (Committee Member); YAKOV LAPITSKY PhD (Committee Member); CONSTANCE SCHALL PhD (Committee Member); MATTHEW FRANCHETTI PhD (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy (PhD), Ohio University, 2015, Chemical Engineering (Engineering and Technology)

The primary objective of this work is to investigate the corrosion behavior of carbon steel in simulated CO2-EOR environments when O2 is present in the CO2 supply. A preliminary study was first conducted at low pressure to investigate the effect of O2 on the protectiveness of iron carbonate (FeCO3) corrosion product layers in mild steel CO2 corrosion. Carbon steel (UNS G10180) samples were immersed in a CO2 saturated 1 wt.% NaCl electrolyte for 2 days to facilitate formation of a protective FeCO3 layer on the steel surface. Temperature and pH were maintained at 80°C and 6.6, then 1 ppm O2 was introduced to the electrolyte. The impact of the oxidant(s) was studied after samples were exposed for one week to test conditions. Electrochemical measurements indicated increased corrosion rates over the first two days of O2 exposure, with a decrease in corrosion rate thereafter due to corrosion product formation that conferred some degree of protection to the steel surface. When O2 was introduced after carbonate formation, the corrosion rate did not increase. Although the final corrosion rates of all tests were relatively low (less than 0.2 mm/y), localized corrosion was observed. Surface analysis showed attack of iron carbonate crystals and formation of iron (III) oxides. This degradation of initially formed FeCO3 occurred concurrently with the development of localized corrosion features as deep as 80 µm. High pressure experiments were then conducted at CO2-EOR simulated downhole conditions. The effect of O2 (4 vol. %) on the corrosion performance of mild steel (UNS G10180) in CO2-saturated brine was investigated using a 4-liter autoclave at two different temperatures (25 and 80°C) and pressures (40 and 90 bar). Experiments at 25°C are categorized as `FeCO3-free' while experiments at 80°C are termed `FeCO3-forming'. The work included electrochemical measurements, weight loss determination, and characterization of the corrosion products. Severe corrosion was observed on (open full item for complete abstract)

Committee: Srdjan Nesic (Advisor); Yoon-Seok Choi (Committee Member); John Staser (Committee Member); Michael Jensen (Committee Member); Dina Lopez (Committee Member) Subjects: Chemical Engineering

Master of Science (MS), Bowling Green State University, 2015, Biological Sciences

Identifying the factors that control soil carbon dioxide emissions will improve our ability to predict the magnitude of climate change-soil ecosystem feedbacks. Despite the integral role of invertebrates in belowground systems, they are excluded from climate change models. Soil invertebrates have consumptive and non-consumptive effects on microbes, whose respiration accounts for nearly half of soil carbon dioxide emissions. By altering the behavior and abundance of invertebrates that interact with microbes, invertebrate predators may have indirect effects on soil respiration. This research examined the effects of a generalist arthropod predator on belowground respiration under different warming scenarios. Based on research suggesting invertebrates may mediate soil carbon dioxide emission responses to warming, predator presence was predicted to result in increased emissions by negatively affecting these invertebrates. Presence of the predator, wolf spiders (Pardosa spp.), was manipulated in mesocosms containing a community of soil invertebrates. To simulate warming, we placed mesocosms of each treatment in ten open-top warming chambers ranging from 1.5 to 5.5° C above ambient at Harvard Forest, MA. Soil carbon dioxide efflux data, microbial abundance, soil moisture, and soil temperature were measured to determine the effects of predators on belowground systems. As expected, carbon dioxide emissions increased under warming and there was an interactive effect of predator presence and warming, though the effect was not consistent through time. The interaction between predator presence and temperature was the inverse of our predictions: mesocosms with predators had lower carbon dioxide emissions at higher temperatures than those without predators. Carbon dioxide emissions were not significantly associated with microbial biomass or soil moisture. There was not find evidence of consumptive effects of predators on the invertebrate community, suggesting that predator presenc (open full item for complete abstract)

Committee: Shannon Pelini Dr. (Advisor); Kevin McCluney Dr. (Committee Member); Michael Weintraub Dr. (Committee Member) Subjects: Biology; Climate Change; Ecology; Soil Sciences

Master of Science in Engineering, University of Akron, 2015, Chemical Engineering

The internal susceptibility and corrosion of pipelines has widely been minimized by the use of inhibitors which mitigate and control degradation effects due to flow conditions and to aggressive environments created inside the pipeline. However, environmental hazard might constitute a problem due to the chemical substances forming the inhibitors. A very specific application of pipeline integrity occurs in offshore facilities for oil recovery production where a mixture of pressurized water-CO2 is injected to almost depleted oil wells in order to enhance recovery. As CO2 injection is very common in marine environments, the effect of chloride ions is added to the corrosive variables of the system is considered. Environmental aggressiveness is set due to a paired effect of environmental conditions: the formation of carbonic acid in the water-CO2 mixture and the presence of chloride ions as part of the marine environment. Here we aimed to electrochemically characterize a zinc-rich epoxy nanocoating primer (ZREP), as well as a composite variation incorporating carbon nanotubes (CNT-ZREP), on an API X52 pipeline grade steel substrate. A rotating cylinder electrode (RCE) was used to incorporate the flow regime and equivalent shear stress conditions. The selected electrolyte for testing was 3% (wt.) NaCl saturated with CO2. The anti-corrosion properties of these nanocomposite coatings are a result of the combined effects of Zn and C nanoelements, which impart special properties not initially inherent in the matrix or in the nanoelements. The effects of these medium conditions on the performance of the substrate/coating system were characterized in real-time by electrochemical impedance spectroscopy. The damage evolution concept was adopted to analyze the current stages and to propose possible mechanisms for the roles of the CNTs and Zn cathodic in providing enhanced protection to the substrate.

Committee: Homero Castaneda-Lopez Dr. (Advisor); Qixin Zhou Dr. (Committee Member); Rajeev Gupta Dr. (Committee Member) Subjects: Chemical Engineering; Chemistry; Engineering

Doctor of Philosophy, University of Toledo, 2014, College of Natural Sciences and Mathematics

Severe weather and climate anomalies have been observed increasingly in recent decades in United States. Large uncertainties still exist about to what extent ecosystems may respond to such drastic variability of external environmental forcing in terms of their carbon sequestration rates. Challenges also remain in predicting and assessing the potential impact of climate variability and anomaly under anticipated climate change. This study targeted the three most prevalent ecosystems (i.e., a deciduous woodland, a conventional cropland, and a coastal freshwater marsh) in northwestern Ohio, USA. Using the eddy covariance method and supplementary measurements, I examined the effects of recent climatic variability and anomalies (2011-2013) on ecosystem carbon fluxes (i.e., net ecosystem CO2/CH4 exchanges (FCO2/FCH4) and lateral hydrologic fluxes of dissolved organic carbon (FDOC), particulate organic carbon (FPOC), and dissolve inorganic carbon (FDIC)). Gross ecosystem production (GEP) and ecosystem respiration (ER) were the two largest fluxes in the annual carbon budget at all three ecosystems. Yet, these two fluxes compensated each other to a large extent and their balance – FCO2 – depended largely on the interannual variability of these two large fluxes. Around 57-58%, 91-96%, and 77-78% of the interannual FCO2 variability was attributed to functional changes of ecosystems among years, suggesting that the changes of ecosystem structural, physiological, or phenological characteristics played an important role in regulating interannual variability of GEP, ER and FCO2. Freshwater marshes deserve more research attention for their high FCH4 (~50.8±1.0 g C m-2 yr-1) and lateral hydrologic carbon inflows/outflows. Lateral hydrologic flows were an important vector in re-locating carbon among ecosystems in the region. Considerable hydrologic carbon flowed both into and out of the research marsh (108.3±5.4 and 86.2±10.5 g C m-2 yr-1, respectively). Despite marshes accounting for (open full item for complete abstract)

Committee: Jiquan Chen (Advisor); Johan Gottgens (Advisor); Richard Becker (Committee Member); Ankur Desai (Committee Member); Ge Sun (Committee Member) Subjects: Ecology; Environmental Science

Master of Science in Environmental Science, Youngstown State University, 2008, Department of Geological and Environmental Sciences

Adsorption is considered one of the more promising technologies for capturing CO2 from flue gases. This research shows an efficient chemical adsorption method capable of capturing carbon dioxide under moist conditions from flue gases of coal-fired power plants. Carbon dioxide was chemically adsorbed by the reaction K2CO3*1.5H2O + CO2 ↔ 2KHCO3 + 0.5H2O + heat. Moisture however, plays a significant role in the chemical adsorption process, which readily facilitates the adsorption process. Moisture usually contained as high as 8-17% in flue gases, badly affects the capacity of conventional adsorbents such as zeolites, but the present technology has no concern with moisture; water is rather necessary in principle as shown in the equation above. Carbon dioxide uptake occurred at a temperature of 60°C and the entrapped carbon dioxide was released by the decomposition of potassium bicarbonate to shift the reaction in the reverse direction. The decomposition occurred at high enough temperatures of 150°C to ensure complete regeneration of the sorbent. For the purpose of this research, emphasis was placed more on the adsorption process. When compared to other processes such as the conventional amine process, it provided an efficient, low utility cost and energy-conservative effect. The activated carbon was prepared by 20% by weight of K2CO3 and samples used during the experimental runs were dried at 60°C for the 26-hour runs and at 25°C and 125°C for the air-dried and oven-dried samples respectively for the 48-hour runs. The samples all got to the saturation point after 6 hours of exposure to carbon dioxide and gave adsorption capacities in the range of 2.5 to 3.5mol CO2/mol K2CO3 for all experimental runs performed in this research.

Committee: Douglas Price PhD (Committee Chair); Felicia Armstrong PhD (Committee Member); Jeffrey Dick PhD (Committee Member); Alan Jacobs PhD (Committee Member) Subjects: Chemical Engineering; Chemistry; Energy; Engineering; Environmental Engineering; Environmental Science

Doctor of Philosophy, The Ohio State University, 2008, Geological Sciences

The latest Ordovician (444 million years ago) was a critical period in Earth history. This was a time of significant climatic global change with large-scale continental glaciation. Moreover, the end-Ordovician mass extinction is recognized as the secondmost devastating mass extinction to have affected the Earth. The anomalous Late Ordovician icehouse period has perplexed many researchers because all previous model and proxy climate evidence suggest high levels of atmospheric CO 2during the Late Ordovician glaciation. Also associated with this period is a large positive carbon isotope(a 13C) excursion (up to +7‰) that represents a global perturbation of the carbon cycle. Additionally, a large decrease (0.001) in seawater 87Sr/ 86Sr occurs several million years prior(~460 million years ago);this could reflect an increase in atmospheric CO 2uptake due to weathering of volcanic rocks involved in uplift of the early Appalachian Mountains. To address these Ordovician anomalies, well-studied, thick, and continuous Late Ordovician limestone sequences from eastern West Virginia, south-central Oklahoma, central Nevada, Quebec (Canada), Estonia, and China have been sampled. Carbon and strontium isotopic ratios have been measured on samples from these localities of which Estonian and Chinese sample sites represent separate paleocontinents (Baltica and South China) and are compared with other data sets from North America. These data test previous interpretations that the well-documented latest Ordovician carbon isotope excursion coincides with maximum glaciation. They support a hypothesis that the large positive carbonate carbon isotope excursion was coincident with a warm interglacial(high CO 2levels) period that separated two major glacial advances (with lowered CO 2levels). There are clear parallels between the Late Ordovician and the Late Cenozoic (the most recent) greenhouse to icehouse transitions, with silicate weathering providing the initiator and positive feedback on c (open full item for complete abstract)

Committee: Matthew Saltzman (Advisor) Subjects: Geochemistry; Geology

Doctor of Philosophy (PhD), Ohio University, 2009, Chemical Engineering (Engineering and Technology)

The internal corrosion of flowlines and pipelines made from carbon steel is encounted in the oil and gas industry. The corrosion process is primarily associated with the presence of free water in offshore or onshore production, particularly when it is accompanied by carbon dioxide gas. Corrosion inhibitor injection in oilfields is a very common and useful method for pipeline internal corrosion prevention. There is a need to understand the physics of phase wetting, carbon dioxide corrosion and the effect of corrosion inhibitor on those two processes in oil-water two-phase flow. In this study, the flow patterns and phase wetting regimes of oil-water two-phase flow were experimentally investigated in a large scale flow loop. Five major flow patterns were observed within the test flow conditions by flow visualization. Three types of phase wetting regimes (water wetting, oil wetting and intermittent wetting) were found by using a carbon steel test section consisting of wall conductance probes, wall sampling and corrosion monitoring. Based on experimental results, phase wetting maps were generated for model oil and five crude oils in the flow loop tests. Following the large scale flow loop tests, a small scale flow apparatus, called a doughnut cell was developed to simulate phase wetting occurring in oil-water two-phase pipe flow. Phase wetting maps were created for model oil and five crude oils in the doughnut cell tests. Two generic inhibitors, quaternary ammonium chloride and fatty amino were studied in this work. Corrosion inhibition tests showed that a direct exposure to oil phase enhances the performance of fatty amino inhibitor. Both inhibitors produce not only a reduction in oil-water interfacail tension, which promotes easier water entrainment by the oil, but also changes the wettability of the steel surface from hydrophilic to hydrophobic, which may reduce the possibility of CO2 corrosion. A mechanistic phase wetting prediciton model was developed to predict the (open full item for complete abstract)

Committee: Srdjan Nesic PhD (Committee Chair); Kevin Crist PhD (Committee Member); Dusan Sormaz PhD (Committee Member); David Ingram PhD (Committee Member); Jeffrey Rack PhD (Committee Member) Subjects: Chemical Engineering

BA, Oberlin College, 2011, Physics and Astronomy

There are a range of environmental and industrial applications to capturing carbon dioxide from gas mixtures. Currently, materials being used in these applications bind carbon dioxide too strongly for practical purposes, such that they require large amounts of energy to be regenerated for reuse. Highly porous materials called metal-organic frameworks (MOFs) could serve much more effectively as carbon-capturing materials, as they suck up large amounts of carbon dioxide gas at pressures and temperatures that are nearly ideal for carbon-capture applications. Moreover, they require much less energy than current materials to release the carbon dioxide and be regenerated. Additionally, many different structures can be created fairly easily, so scientists are on the hunt for the ideal carbon-capturing MOF. In this thesis we study Mg-MOF-74, a particularly promising metal-organic framework material for separating carbon dioxide from gas mixtures. We use infrared spectroscopy to probe the interactions between the Mg-MOF-74 host and both carbon dioxide and methane. By shining infrared radiation on Mg-MOF-74 with gases trapped in it and looking at which frequencies of radiation are absorbed by the bound gases, we can learn about the binding nature of the framework. This in turn helps us to better understand the properties are are preferable in metal organic frameworks, and will aid chemists in fabricating new structures that are ideal for carbon-capture and other applications.

Committee: Stephen FitzGerald PhD (Advisor) Subjects: Molecular Physics; Physical Chemistry; Physics