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Title: CONTROL OF HYDROGEN SULFIDE EMISSIONSUSING AUTOTROPHIC DENITRIFICATIONLANDFILL BIOCOVERS.
Creator: Sungthong, Daoroong, Reinhart, Debra, University of Central Florida
Abstract / Description: Hydrogen sulfide (H2S), a major odorous component emitted from construction and demolition debris landfills, has received increasing attention. Besides its unpleasant odor, long-term exposure to a very low concentration of H2S can cause a public health issue. Although cover materials such as soil and compost are recommended to be used routinely to control an odor problem from the landfills, the problem still remains. Autotrophic denitrification may have environmental applications including...
Show moreHydrogen sulfide (H2S), a major odorous component emitted from construction and demolition debris landfills, has received increasing attention. Besides its unpleasant odor, long-term exposure to a very low concentration of H2S can cause a public health issue. Although cover materials such as soil and compost are recommended to be used routinely to control an odor problem from the landfills, the problem still remains. Autotrophic denitrification may have environmental applications including treatment of water, groundwater, wastewater or gaseous streams contaminated with sulfur and/or nitrogen compounds. However, there have been no studies reported in the literature on H2S removal using autotrophic denitrification from landfills. This study, therefore, investigated the application of autotrophic denitrification incorporated into landfill covers in order to evaluate the feasibility of controlling H2S emissions generated from landfills. Research was investigated by two techniques, microcosm and laboratory-scale column studies. The microcosm experiments were conducted to evaluate the kinetics of autotrophic denitrification in various cover materials with H2S-nitrate as electron donor-acceptor couple. Cover materials including soil, compost and sand were tested and nitrate was added. Based on the microcosm study results, the addition of nitrate into soil and compost can stimulate indigenous autotrophic denitrifying bacteria which are capable of H2S oxidation biologically under anoxic conditions. Results also demonstrated that some amount of H2S can be removed physically and chemically by soil or compost. There was no H2S removal observed in sand microcosms. Rapid H2S oxidation to sulfate was achieved, especially in soil. Zero-order kinetics described the H2S oxidation rate in soil and compost microcosms. The rates of sulfide oxidation under autotrophic denitrification in soil and compost were 2.57 mg H2S/d-g dry soil and 0.17 mg H2S/d-g dry compost, respectively. To further explore H2S removal in a landfill biocover, two sets of column experiments were run. The first set of columns contained seven cm of soil. The autotrophic column was prepared with 1.94 mg KNO3/g dry soil; an identical control column was prepared without nitrate. A gas stream was introduced to the columns with a H2S concentration of 930 ppm. The second set contained seven cm of soil, with both an autotrophic (0.499 mg KNO3/g dry soil) and a control column. Influent H2S concentration was 140 ppm for the second set. Column studies supported the results of microcosm studies; removal of H2S was observed in all columns due to the capacity for soil to absorb H2S, however autotrophic columns removed significantly more. The higher concentration of H2S resulted in partial oxidation to elemental sulfur, while sulfate was found at levels predicted by stoichiometric relationships at the lower concentration. H2S oxidation in the column with higher loading was found to follow zero-order kinetics. The rate of H2S oxidation was 0.46 mg H2S removed/d-g dry soil. Economic comparison of cover systems including autotrophic denitrification, soil amended with lime, fine concrete, and compost covers were analyzed. Based on a case-study landfill area of 0.04 km2, the estimated H2S emissions of 80,900 kg over the 15-year period and costs of active cover system components (ammonium nitrate fertilizer, lime, concrete and compost), autotrophic denitrification cover was determined to be the most cost-effective method for controlling H2S emissions from landfills.
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Date Issued: 2010
Identifier: CFE0003283, ucf:48537
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003283

Title: Development of enzyme-free hydrogen peroxide biosensor using cerium oxide and mechanistic study using in-situ spectro-electrochemistry.
Creator: Saraf, Shashank, Seal, Sudipta, Cho, Hyoung Jin, Zhai, Lei, Heinrich, Helge, Harper, James, University of Central Florida
Abstract / Description: During recent development, it has been demonstrated that cerium oxide nanoparticles (CNPs) have exhibited catalytic activity which mimics naturally existing enzymes such as superoxide dismutase (SOD) and catalase. The underlying mechanism is attributed to the modulation of oxygen vacancies on CNPs lattice by dynamic switching of the oxidation states between Ce3+ and Ce4+ due to the electron transfer resulting from the redox reaction between CNPs and reactive oxygen species such as hydrogen...
Show moreDuring recent development, it has been demonstrated that cerium oxide nanoparticles (CNPs) have exhibited catalytic activity which mimics naturally existing enzymes such as superoxide dismutase (SOD) and catalase. The underlying mechanism is attributed to the modulation of oxygen vacancies on CNPs lattice by dynamic switching of the oxidation states between Ce3+ and Ce4+ due to the electron transfer resulting from the redox reaction between CNPs and reactive oxygen species such as hydrogen peroxide (H2O2). Thereby the redox potential of CNPs is dependent on the surface chemistry i.e. the surface concentration of Ce3+ and Ce4+ Currently, the ratio of Ce3+/ Ce4+ in CNPs is characterized ex-situ using XPS or TEM which involves sample drying and exposure to high energy X-rays and electron beam, respectively. Sample drying and high energy beam exposure could lead to sample deterioration. The goal of the study is to explore a technique to characterize CNPs in-situ and identify the surface chemistry of CNPs. The in-situ investigation of CNPs was carried using spectroelectrochemistry wherein the electrochemical and optical measurements are carried out simultaneously. Detailed optical characterization of two different CNPs having different catalytic activity were carried under oxidation and reduction environments. Analysis of spectra revealed widely different redox potential for CNPs which was a function of pH and composition of buffer solution. In second part of dissertation a suitable surface chemistry of CNPs is investigated to replace the enzyme in biosensor assembly to allow amperometric detection of H2O2 in physiological conditions. Upon electrochemical investigation of the physio-chemical properties of CNPs, it was found that CNPs having higher surface concentration of Ce4+ as compared to Ce3+ oxidation states, demonstrated increased catalytic activity towards H2O2. The addition of CNPs resulted in 5 orders of increment in amperometric current with a response time of 400 msec towards detection of H2O2 and exhibited excellent selectivity in presence of interfering species. Additionally, cerium oxide was successfully integrated into the biosensor assembly through the anodic electrodeposition, which allowed the transfer of electron generated from the CNPs in the redox reaction to the electrode and demonstrated successful sensing of H2O2. Furthermore, to achieve detection of H2O2 in physiological conditions, CNPs were integrated with nanoporous gold (NPG) which exhibited anti-biofouling properties. The anti-biofouling property of NPG was investigated using electrochemical techniques and showed excellent signal retention in physiological concentration of albumin proteins. The novel study targets at developing robust enzyme free biosensor by integrating the detection ability of CNPs with the anti-biofouling activity of NPG based electrode.
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Date Issued: 2016
Identifier: CFE0006498, ucf:51404
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006498

Title: INVESTIGATING THE QUANTITY AND TYPES OF MICROPLASTICS IN THE ORGANIC TISSUE OF OYSTERS AND CRABS IN THE INDIAN RIVER LAGOON.
Creator: Waite, Heidi, Walters, Linda J., University of Central Florida
Abstract / Description: Microplastics are widespread and abundant. Few studies have examined the diversity and abundance of microplastics in wild organisms. This study determined the microplastic quantity and types in the organic tissues of the eastern oyster Crassostrea virginica and Atlantic mud crab Panopeus herbstii from the Indian River Lagoon (IRL). This study also investigated whether location affected the microplastic abundance and variety. Organisms were collected from three sites across Mosquito Lagoon in...
Show moreMicroplastics are widespread and abundant. Few studies have examined the diversity and abundance of microplastics in wild organisms. This study determined the microplastic quantity and types in the organic tissues of the eastern oyster Crassostrea virginica and Atlantic mud crab Panopeus herbstii from the Indian River Lagoon (IRL). This study also investigated whether location affected the microplastic abundance and variety. Organisms were collected from three sites across Mosquito Lagoon in the northern IRL. Oysters were frozen after collection. Crabs were placed in containers for 5 days before freezing. The soft organic tissue was chemically digested using hydrogen peroxide, filtered, and examined for microplastics. Water samples collected from each study site had an average of 23.1 microplastic pieces per liter and fibers were the most common type. There was a significant interaction for microplastic type and site for both oysters and crabs (p
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Date Issued: 2017
Identifier: CFH2000157, ucf:46042
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000157

Title: DIMESIONALITY ASPECTS OF NANO MICRO INTEGRATED METAL OXIDE BASED EARLY STAGE LEAK DETECTION ROOM TEMPERATURE HYDROGEN SENSOR.
Creator: Deshpande, Sameer, Seal, Sudipta, University of Central Florida
Abstract / Description: Detection of explosive gas leaks such as hydrogen (H2) becomes key element in the wake of counter-terrorism threats, introduction of hydrogen powered vehicles and use of hydrogen as a fuel for space explorations. In recent years, a significant interest has developed on metal oxide nanostructured sensors for the detection of hydrogen gas. Gas sensors properties such as sensitivity, selectivity and response time can be enhanced by tailoring the size, the shape, the structure and the surface of...
Show moreDetection of explosive gas leaks such as hydrogen (H2) becomes key element in the wake of counter-terrorism threats, introduction of hydrogen powered vehicles and use of hydrogen as a fuel for space explorations. In recent years, a significant interest has developed on metal oxide nanostructured sensors for the detection of hydrogen gas. Gas sensors properties such as sensitivity, selectivity and response time can be enhanced by tailoring the size, the shape, the structure and the surface of the nanostructures. Sensor properties (sensitivity, selectivity and response time) are largely modulated by operating temperature of the device. Issues like instability of nanostructures at high temperature, risk of hydrogen explosion and high energy consumption are driving the research towards detection of hydrogen at low temperatures. At low temperatures adsorption of O2- species on the sensor surface instead of O- (since O- species reacts easily with hydrogen) result in need of higher activation energy for hydrogen and adsorbed species interaction. This makes hydrogen detection at room temperature a challenging task. Higher surface area to volume ratio (resulting higher reaction sites), enhanced electronic properties by varying size, shape and doping foreign impurities (by modulating space charge region) makes nanocrystalline materials ideal candidate for room temperature gas sensing applications. In the present work various morphologies of nanostructured tin oxide (SnO2) and indium (In) doped SnO2 and titanium oxide (titania, TiO2) were synthesized using sol-gel, hydrothermal, thermal evaporation techniques and successfully integrated with the micro-electromechanical devices H2 at ppm-level (as low as 100ppm) has been successfully detected at room temperature using the SnO2 nanoparticles, SnO2 (nanowires) and TiO2 (nanotubes) based MEMS sensors. While sensor based on indium doped tin oxide showed the highest sensitivity (S =Ra/Rg= 80000) and minimal response time (10sec.). Highly porous SnO2 nanoparticles thin film (synthesized using template assisted) showed response time of about 25 seconds and sensitivity 4. The one dimensional tin oxide nanostructures (nanowires) based sensor showed a sensitivity of 4 and response time of 20 sec. Effect of aspect ratio of the nanowires on diffusion of hydrogen molecules in the tin oxide nanowires, effect of catalyst adsorption on nanowire surface and corresponding effect on sensor properties has been studied in detail. Nanotubes of TiO2 prepared using hydrothermal synthesis showed a sensitivity 30 with response time as low as 20 seconds where as, TiO2 nanotubes synthesized using anodization showed poor sensitivity. The difference is mainly attributed to the issues related to integration of the anodized nanotubes with the MEMS devices. The effect of MEMS device architecture modulation, such as, finger spacing, number and length of fingers and electrode materials were studied. It has been found that faster sensor response (~ 10 sec) was observed for smaller finger spacing. A diffusion model is proposed for elucidating the effect of inter-electrode distance variation on conductance change of a nano-micro integrated hydrogen sensor for room temperature operation. Both theoretical and experimental results showed a faster response upon exposure to hydrogen when sensor electrode gap was smaller. Also, a linear increase in the sensor sensitivity from 500 to 80000 was observed on increasing the electrode spacing from 2 to 20 μm. The improvement in sensitivity is attributed to the higher reactive sites available for the gaseous species to react on the sensor surface. This phenomenon also correlated to surface adsorbed oxygen vacancies (O-) and the rate of change of surface adsorbed oxygen vacancies. This dissertation studied in detail dimensionality aspects of materials as well as device in detecting hydrogen at room temperature.
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Date Issued: 2007
Identifier: CFE0001985, ucf:47420
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001985

Title: RECOVERY OF HYDROGEN AND HELIUM FROM THEIR MIXTURES USING METAL HYDRIDES.
Creator: Oztek, Muzaffer, Hampton, Michael, University of Central Florida
Abstract / Description: Waste streams of hydrogen and helium mixtures are produced at the Kennedy Space Center during purging of the hydrogen systems and supply lines. This process is done prior to and after hydrogen servicing. The purged waste gases are lost to the atmosphere, resulting in an annual loss of 2 million and 0.1 million standard cubic meters of helium and hydrogen, respectively. Recovery of these gases will have an economic benefit. Metals, alloys, and intermetallics are known to react with hydrogen in...
Show moreWaste streams of hydrogen and helium mixtures are produced at the Kennedy Space Center during purging of the hydrogen systems and supply lines. This process is done prior to and after hydrogen servicing. The purged waste gases are lost to the atmosphere, resulting in an annual loss of 2 million and 0.1 million standard cubic meters of helium and hydrogen, respectively. Recovery of these gases will have an economic benefit. Metals, alloys, and intermetallics are known to react with hydrogen in favorable conditions; therefore, they have the possibility of serving as separating and recovery agents. In this study, Mg2Ni, VTiNi and LaNi5 were studied for the separation of H2 from He, using differential scanning calorimetry and thermal volumetric analysis. The ability of LaNi5 to react with hydrogen reversibly at room temperature was verified, and further analysis focused on this compound. Size reduction and activation of LaNi5 by mechanical milling was investigated using different milling parameters for the purpose of activating the material for hydrogen absorption. Because it has been shown that addition of aluminum to LaNi5 resulted in improved hydriding and dehydriding properties, that system was studied further here. In this study, aluminum was added to LaNi5 by mechanical milling. Hydriding properties and elemental compositions of the samples were determined afterwards. The hydrogen absorption rate and capacity were compared to that of LaNi5. Both LaNi5 and its Al doped derivatives exhibited a reduced rate of hydrogen uptake and a reduced hydrogen capacity in the presence of helium. The effects of coating the samples with either gold-palladium or platinum were investigated. It was observed that coating the samples with Pt reduced the negative effect of He, whereas AuPd coating did not have any effect. Larger scale studies were done using a continuous U-tube hydride reactor, built and tested for separation of H2¬ from a 20:80 H2:He mixture. The amount of hydrogen retained in the bed was determined and found to be less than that for the batch systems.
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Date Issued: 2005
Identifier: CFE0000660, ucf:46507
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000660

Title: MICROMACHINED ELECTROCHEMICAL SENSORS FOR HYDROGEN PEROXIDE AND CHLORINE DETECTION.
Creator: Mehta, Anjum, Cho, Hyoung (Joe), University of Central Florida
Abstract / Description: Hydrogen peroxide and chlorine detection is critical for many biological and environmental applications. Hydrogen peroxide plays important roles in a variety of fields including plant physiology, medical, environmental and biochemical applications. Its role in plant defense and signal transduction, diseases such as Parkinson's and Alzhemier's, industrial processes such as disinfection and wastewater treatment and biochemical enzymatic reactions is critical. Given the gamut of areas that...
Show moreHydrogen peroxide and chlorine detection is critical for many biological and environmental applications. Hydrogen peroxide plays important roles in a variety of fields including plant physiology, medical, environmental and biochemical applications. Its role in plant defense and signal transduction, diseases such as Parkinson's and Alzhemier's, industrial processes such as disinfection and wastewater treatment and biochemical enzymatic reactions is critical. Given the gamut of areas that hydrogen peroxide is a key component of; its detection assumes great importance. Similarly chlorine has long been used as a disinfectant for making drinking water safe, but excessive chlorination is an environmental and health hazard in itself. In this work, micromachining techniques have been used to design, fabricate and test electrochemical sensors and microneedle structure that can be integrated for detection of hydrogen peroxide and free chlorine. A novel nanomaterial has been integrated with the hydrogen peroxide microsensor, which greatly increases the sensor lifetime and robustness. Miniaturization, low detection limits, high sensitivity and selectivity, as well as ease of fabrication are some of the other advantages of this work.
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Date Issued: 2005
Identifier: CFE0000895, ucf:46627
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000895

Title: SOLAR DRIVEN PHOTOELECTROCHEMICAL WATER SPLITTING FOR HYDROGEN GENERATION USING MULTIPLE BANDGAP TANDEM OF CIGS2 PV CELLS AND THIN FILM PHOTOCATALYST.
Creator: Jahagirdar, Anant, Dhere, Neelkanth, University of Central Florida
Abstract / Description: The main objective of this research was to develop efficient CuIn1-xGaxS2 (CIGS2)/CdS thin film solar cells for photoelectrochemical (PEC) water splitting to produce very pure hydrogen and oxygen. Efficiencies obtained using CIGS2 have been lower than those achieved using CuInSe2 and CuIn1-xGaxSe2. The basic limitation in the efficiencies is attributed to lower open circuit voltages with respect to the bandgap of the material. Presently, the main mechanism used to increase the open circuit...
Show moreThe main objective of this research was to develop efficient CuIn1-xGaxS2 (CIGS2)/CdS thin film solar cells for photoelectrochemical (PEC) water splitting to produce very pure hydrogen and oxygen. Efficiencies obtained using CIGS2 have been lower than those achieved using CuInSe2 and CuIn1-xGaxSe2. The basic limitation in the efficiencies is attributed to lower open circuit voltages with respect to the bandgap of the material. Presently, the main mechanism used to increase the open circuit voltage of these copper chalcopyrites (CuInSe2 and CuInS2) is the addition of gallium. However, addition of gallium has its own challenges. This research was intended to (i) elucidate the advantages and disadvantages of gallium addition, (ii) provide an alternative technique to the photovoltaic (PV) community to increase the open circuit voltage which is independent of gallium additions, (iii) develop highly efficient CIGS2/CdS thin film solar cells and (iv) provide an alternative material in the form of CIGS2/CdS thin film solar cells and an advanced technology in the form of a multiple bandgap tandem for PEC water splitting. High gallium content was achieved by the incorporation of a highly excess copper composition. Attempts to achieve high gallium content produced reasonable but not the best solar cell performance. Few solar cells developed on a molybdenum back contact and an ITO/MoS2 transparent conducting back contact showed a PV conversion efficiency of 7.93% and 5.97%, respectively. The solar cells developed on the ITO/MoS2 back contact form the first generation CIGS2/CdS thin film solar cells and 5.97% is the first ever reported efficiency on an ITO/MoS2 transparent back contact. Reasons for the moderate performance of these solar cells were attributed to significant porosity and remnants of unsulfurized CuGa alloy in the bulk of CIGS2. This was the first attempt to a detailed study of materials and device characteristics of CIGS2/CdS thin film solar cells prepared starting with a highly excess copper content CIGS2 layer. Next, excess copper composition of 1.4 (equivalent to gallium content, x = 0.3) was chosen with the aim to achieve the best efficiency. The open circuit voltage was enhanced by depositing an intermediate layer of intrinsic ZnO between CdS and ZnO:Al layers. The systematic study of requirements for such a layer and further optimization of its thickness to achieve a higher open circuit voltage (which is the greatest challenge of the scientific community) forms an important scientific contribution of this research. The PV parameters for CIGS2/CdS thin film solar cell as measured officially at the National Renewable Energy Laboratory were: open circuit voltage of 830.5 mV, short circuit current density of 21.88 mA/cm2, fill factor of 69.13% and photovoltaic conversion efficiency of 11.99% which sets a new world record for CIGS2 cells developed using sulfurization and the open circuit voltage of 830.5 mV has become the "Voc champion value". New PEC setups with the RuS2 and Ru0.99Fe0.01S2 photoanodes were developed. RuS2 and Ru0.99Fe0.01S2 photoanodes were more stable in the electrolyte and showed better I-V characteristics than the RuO2 anode earlier used. Using two CIGS2/CdS thin film solar cells, a PEC efficiency of 8.78% was achieved with a RuS2 anode and a platinum cathode. Results of this research constitute a significant advance towards achieving practical feasibility and industrially viability of the technology of PEC hydrogen generation by water splitting.
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Date Issued: 2005
Identifier: CFE0000871, ucf:46666
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000871

Title: CHARACTERIZATION OF HEMERYTHRIN-LIKE PROTEIN RV2633C.
Creator: Cherne, Michelle D, Self, William, University of Central Florida
Abstract / Description: Hemerythrin-like protein Rv2633c is a small 18 kDa protein that is expressed in Mycobacterium tuberculosis (Mtb). Sequence analysis of Rv2633c predicts the presence of a hemerythrin-like domain, which binds dioxygen using a �-oxo-bridge (Fe-O-Fe), rather than a heme group. Though it is noticeably upregulated during macrophage infection and during in vitro acidification, the role of Rv2633c in Mtb survival has yet to be elucidated. This project aims to characterize the function of Rv2633c by...
Show moreHemerythrin-like protein Rv2633c is a small 18 kDa protein that is expressed in Mycobacterium tuberculosis (Mtb). Sequence analysis of Rv2633c predicts the presence of a hemerythrin-like domain, which binds dioxygen using a �-oxo-bridge (Fe-O-Fe), rather than a heme group. Though it is noticeably upregulated during macrophage infection and during in vitro acidification, the role of Rv2633c in Mtb survival has yet to be elucidated. This project aims to characterize the function of Rv2633c by studying the in vitro response of the recombinant protein to conditions present in the macrophage lysosome, such as reduced oxygen levels or the presence of reactive oxygen species. UV-visible spectroscopy is used to observe these changes, as the spectrum shows a characteristic peak at 330 nm that likely corresponds to the diiron cofactor in its native state. Our results show this spectrum shifts in response to hydrogen peroxide addition, showing the proposed environmental conditions can affect the active site. Bioinformatics techniques, such as the 3D modeling program SWISS-MODEL, have been used to hypothesize possible structure and function. Determining the function of Rv2633c may help explain how Mtb so readily evades the human immune system to reside in the macrophage.
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Date Issued: 2016
Identifier: CFH2000011, ucf:45581
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH2000011

Title: Large Scale Cryogenic Storage With Active Refrigeration.
Creator: Swanger, Adam, Chow, Louis, Kapat, Jayanta, Notardonato, William, University of Central Florida
Abstract / Description: Storage and transfer of cryogenic liquefied gases on volume scales from under 10 liters for lab use, up to hundreds of millions of liters for industrial applications is of paramount importance across a vast range of industries. Traditionally, these commodities have been stored at or near the normal boiling point due to relative ease of operation and safety-related considerations; however, this also means that some percentage will always be lost due to environmental heat leaking into the...
Show moreStorage and transfer of cryogenic liquefied gases on volume scales from under 10 liters for lab use, up to hundreds of millions of liters for industrial applications is of paramount importance across a vast range of industries. Traditionally, these commodities have been stored at or near the normal boiling point due to relative ease of operation and safety-related considerations; however, this also means that some percentage will always be lost due to environmental heat leaking into the vessel and causing boiloff. These losses become more concerning as scales increase, and are of particular importance for high-cost commodities such helium and hydrogen. Additionally, the normal boiling point has typically marked the highest liquid density achievable, which became a strong driver of end-use system designs such as space launch vehicles. Recent development and testing of an Integrated Refrigeration and Storage (IRAS) system for liquid hydrogen has proven that next generation cryogenic storage operations such as zero boiloff and densification are feasible on a large scale. This IRAS system married an 850 Watt at 20 Kelvin reverse-Brayton cycle commercial cryogenic refrigerator with a 125,000 liter LH2 storage tank via an internal tubular heat exchanger; thereby allowing heat to be removed directly from the hydrogen, and by extension, providing a means to control the bulk thermodynamic state. Tests of zero boiloff, in-situ liquefaction, and densification down to the triple point were performed, and data including fluid temperature profiles and tank pressure were gathered. Details regarding the design, setup, and testing of the IRAS system are discussed herein, and the data are used to anchor various physics models created to predict the behavior of the system during both transient and steady state operations. Hopefully these efforts will provide a useful basis for the design and implementation of future large scale IRAS systems across numerous industries.
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Date Issued: 2018
Identifier: CFE0007588, ucf:52530
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007588

Title: PREDICTIVE MODELING OF SULFIDE REMOVAL IN TRAY AERATORS.
Creator: Faborode, Jumoke, Reddi, Lakshmi, University of Central Florida
Abstract / Description: Hydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive...
Show moreHydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive mathematical model that could be used to determine tray effectiveness for sulfide removal. A literature review was performed that indicated there was limited information regarding the removal of hydrogen sulfide using conventional tray aerators, and no information regarding the removal of total sulfide from tray aerators. There was significantly more information available in the literature regarding the usefulness of sulfide removal technologies from water supplies. Consequently, the lack of literature regarding sulfide removal using tray aerators suggested that there was a need for additional research focused on sulfide removal from water flowing thru tray aerators. Several water purveyors that relied on tray aerators as a part of their water treatment operations were contacted and requested to participate in the study; three water purveyors agreed to allow the University of Central Florida (UCF) to enter their secured sites to collect samples and conduct this study. The three facilities included the UCFÃ‚Â's water treatment plant located in Orlando and situated in eastern Orange County, the City of Lake HamiltonÃ‚Â's water treatment plant located in west-central Polk County, and the Sarasota-Verna water treatment plant located in western Sarasota County. An experimental plan was developed and field sampling protocols were implemented to evaluate sulfide removal in commonly used tray aerators at the three drinking water treatment facilities. Total sulfide concentrations passing through the trays were determined in the field at each site using a standard iodometric analytical technique. In addition, other water quality parameters collected included dissolved oxygen, pH, temperature, conductivity, turbidity, alkalinity, hardness, total dissolved solids and total suspended solids; these samples were collected and analyzed either in the field or at the UCF laboratory. A first-order empirical model was developed that predicted sulfide removal in tray aerators. The modelÃ‚Â's constant was evaluated with respect to the waterÃ‚Â's proton concentration , the tray aeratorÃ‚Â's surface area, and hydraulic flow rate thru the trays. The selected model took the form of Cn=C0 (10-kn) where Cn is the sulfide remaining after aeration in mg/L, C0 is the sulfide entering the distribution tray in mg/L, n is the number of tray stages in the aerator, and k=(0.00248)(H^+ )^(-0.397) (Area)^0.584 (Flow)^(-1.17). From the empirical model, it was shown that sulfide removal was negatively impacted as the proton concentration (H+) decreased, and flow increased. Conversely, it was observed that increased sulfide removal occurred as the available tray aerator surface area increased. The combined parameters of proton concentration, flow rate, and area were statistically evaluated and used to develop an empirical constant that could be used in a first order model to predict sulfide removal in tray aerators. Using a site-specific derived experimental (empirical) constant, a water purveyor could use the developed model from this work to accurately predict sulfide removal in a tray aerator by simply measuring the total sulfide content in any raw groundwater supply and then providing the desired number of tray stages available for treatment.
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Date Issued: 2010
Identifier: CFE0003518, ucf:48980
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003518

Title: The safe removal of frozen air from the annulus of a liquid hydrogen storage tank.
Creator: Krenn, Angela, Bhattacharya, Aniket, Youngquist, Robert, Vasu Sumathi, Subith, University of Central Florida
Abstract / Description: Large Liquid Hydrogen (LH2) storage tanks are vital infrastructure for NASA. Eventually, air may leak into the evacuated and perlite filled annular region of these tanks. Although the vacuum level is monitored in this region, the extremely cold temperature causes all but the helium and neon constituents of air to freeze. A small, often unnoticeable pressure rise is the result. As the leak persists, the quantity of frozen air increases, as does the thermal conductivity of the insulation system...
Show moreLarge Liquid Hydrogen (LH2) storage tanks are vital infrastructure for NASA. Eventually, air may leak into the evacuated and perlite filled annular region of these tanks. Although the vacuum level is monitored in this region, the extremely cold temperature causes all but the helium and neon constituents of air to freeze. A small, often unnoticeable pressure rise is the result. As the leak persists, the quantity of frozen air increases, as does the thermal conductivity of the insulation system. Consequently, a notable increase in commodity boiloff is often the first indicator of an air leak. Severe damage can then result from normal draining of the tank. The warming air will sublimate which will cause a pressure rise in the annulus. When the pressure increases above the triple point, the frozen air will begin to melt and migrate downward. Collection of liquid air on the carbon steel outer shell may chill it below its ductility range, resulting in fracture. In order to avoid a structural failure, as described above, a method for the safe removal of frozen air is needed. Two potential methods for air removal are evaluated here. The first method discussed is the connection of a vacuum pump to the annulus which provides pumping in parallel with drainage of LH2. The goal is to keep the annular pressure below the triple point so that the air continues to sublimate, thus eliminating the threat that liquefaction poses. The second method discussed is the application of heat to the bottom of the outer tank during tank drain. Though liquefaction in the annular space will occur, the goal of the heater design is to keep the outer shell above the embrittlement temperature, so that cracking will not occur.In order to evaluate these methods, it is first necessary to characterize some the physical properties and changes that take place in the system. A thermal model of the storage tank was created in SINDA/FLUINT (C(&)R Technologies, 2014) to identify locations where air can freeze. This model shows the volume that is capable of freezing air under varying conditions. It is also necessary to characterize the changes in thermal conductivity of perlite which has nitrogen frozen into its interstitial spaces. The details and results of an experiment designed for that purpose is outlined. All data, including operational data from existing LH2 tanks, is compiled and a physics-based evaluation of the two proposed air removal techniques is performed.Due to small pumping capacities at low pressure and the large quantity of air inside the annulus, the pumping option is not deemed feasible. It would take many years to remove a significant amount of air by pumping while maintaining the annular pressure below the necessary triple point. Application of heating devices is a feasible option. For a specific case, it is shown that approximately 105 kilowatts of power would be required to vaporize the air in the annulus and keep the temperature of the outer tank wall above the freezing point of water. Several engineering solutions to accomplish this are also discussed. There are many unknowns and complexities in addressing the problem of safely removing frozen air from the annulus of an LH2 storage sphere. The work that follows utilized: research, modeling, experimentation, analysis, and data from existing tanks to arrive at possible solutions to the problem. Heating solutions may be implemented immediately and could result in significant savings to the user.
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Date Issued: 2015
Identifier: CFE0005969, ucf:50766
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005969

Title: Electronic properties and atomic scale microscopy of two dimensional materials: graphene and molybdenum disulfide.
Creator: Katoch, Jyoti, Ishigami, Marsahir, Mucciolo, Eduardo, Del Barco, Enrique, Coffey, Kevin, University of Central Florida
Abstract / Description: Novel two dimensional nanoscale materials like graphene and metal dichalcogenides (MX2) have attracted the attention of the scientific community, due to their rich physics and wide range of potential applications.It has been shown that novel graphene based transparent conductors and radiofrequency transistors are competitive with the existing technologies. Graphene's properties are influenced sensitively by adsorbates and substrates. As such not surprisingly, physical properties of graphene...
Show moreNovel two dimensional nanoscale materials like graphene and metal dichalcogenides (MX2) have attracted the attention of the scientific community, due to their rich physics and wide range of potential applications.It has been shown that novel graphene based transparent conductors and radiofrequency transistors are competitive with the existing technologies. Graphene's properties are influenced sensitively by adsorbates and substrates. As such not surprisingly, physical properties of graphene are found to have a large variability, which cannot be controlled at the synthesis level, reducing the utility of graphene. As a part of my doctorate dissertation, I have developed atomic hydrogen as a novel technique to count the scatterers responsible for limiting the carrier mobility of graphene field effect transistors on silicon oxide (SiO2) and identified that charged impurities to be the most dominant scatterer. This result enables systematic reduction of the detrimental variability in device performance of graphene. Such sensitivity to substrates also gives an opportunity for engineering device properties of graphene using substrate interaction and atomic scale vacancies. Stacking graphene on hexagonal boron-nitride (h-BN) gives rise to nanoscale periodic potential, which influences its electronic graphene. Using state-of-the-art atomic-resolution scanning probe microscope, I correlated the observed transport properties to the substrate induced extrinsic potentials. Finally in efforts to exploit graphene's sensitivity to discover new sensor technologies, I have explored noncovalentfunctionalization of graphene using peptides.Molybdenum disulfide (MoS2) exhibits thickness dependent bandgap. Transistors fabricated from single layer MoS2 have shown a high on/off ratio. It is expected that ad-atom engineering can be used to induce on demand a metal-semiconductor transition in MoS2. In this direction, I have explored controlled/reversible fluorination and hydrogenation of monolayer MoS2 to potentially derive a full range of integrated circuit technology. The in-depth characterization of the samples is carried out by Raman/photoluminescence spectroscopy and scanning tunneling microscopy.
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Date Issued: 2014
Identifier: CFE0005190, ucf:50614
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005190

Title: Development of Novel Redox Sensors and Processes Towards Biological Applications.
Creator: Patel, Jigna, Yestrebsky, Cherie, Clausen, Christian, Hampton, Michael, Harper, James, Diaz, Diego, University of Central Florida
Abstract / Description: Research on the cure and early detection of diseases such as diabetes, Alzheimer's, and Parkinson's is becoming of great interest due to the increasing number of people affected by them every year. An accurate and quick detection of various damaging species is highly critical in treatments of such diseases not only for exploring possible cures but also for early detection. If these diseases are detected during the initial stages than the possibility of curing them is much higher. Motivated by...
Show moreResearch on the cure and early detection of diseases such as diabetes, Alzheimer's, and Parkinson's is becoming of great interest due to the increasing number of people affected by them every year. An accurate and quick detection of various damaging species is highly critical in treatments of such diseases not only for exploring possible cures but also for early detection. If these diseases are detected during the initial stages than the possibility of curing them is much higher. Motivated by this, many researchers today have developed numerous types of sensing devices that can detect various physiological and biological compounds. However, most of these sensors are enzyme based. They have several setbacks such as the lack of sensitivity, restricted selectivity, short shelf life, and biological fouling. To overcome these obstacles, we examine the use of nanoceria modified Pt and Au electrodes for the detection of glucose and reactive oxygen species such as hydrogen peroxide. Amperometric detection of glucose and hydrogen peroxide is critical for biological applications for diabetes and possible Alzheimer's and Parkinson's patients. This dissertation focuses on the exploration of non-enzymatic detection of glucose and reactive oxygen species which has the prospective to be used for biological applications, in addition to an investigation of an odor control technology that uses these reactive oxygen species for the treatment of wastewater plants. The combination of bi-metallic composites with nanoceria showed increased oxidation ability towards glucose and hydrogen peroxide. The following dissertation expands on the relationship between bi-metallic nanoceria composite materials and its electro-oxidation of glucose and hydrogen peroxide towards biological sensing along with an investigation of an odor control technology that utilizes generates hydroxyl radical fine particle mist for the degradation of hydrogen sulfide odor in wastewater treatment plants.
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Date Issued: 2013
Identifier: CFE0005227, ucf:50585
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005227

Title: DESIGN AND FABRICATION OF CHEMIRESISTOR TYPEMICRO/NANO HYDROGEN GAS SENSORS USINGINTERDIGITATED ELECTRODES.
Creator: Zhang, Peng, Cho, Hyoung Jin, University of Central Florida
Abstract / Description: Hydrogen sensors have obtained increased interest with the widened application of hydrogen energy in recent years. Among them, various chemiresistor based hydrogen sensors have been studied due to their relatively simple structure and well-established detection mechanism. The recent progress in micro/nanotechnology has accelerated the development of small-scale chemical sensors. In this work, MEMS (Micro-Electro-Mechanical Systems) sensor platforms with interdigitated electrodes have been...
Show moreHydrogen sensors have obtained increased interest with the widened application of hydrogen energy in recent years. Among them, various chemiresistor based hydrogen sensors have been studied due to their relatively simple structure and well-established detection mechanism. The recent progress in micro/nanotechnology has accelerated the development of small-scale chemical sensors. In this work, MEMS (Micro-Electro-Mechanical Systems) sensor platforms with interdigitated electrodes have been designed and fabricated. Integrating indium doped tin dioxide nanoparticles, these hydrogen sensors showed improved sensor characteristics such as sensitivity, response and selectivity at room temperature. Design parameters of interdigitated electrodes have been studied in association with sensor characteristics. It was observed that these parameters (gap between the electrodes, width and length of the fingers, and the number of the fingers) imposed different impacts on the sensor performance. In order to achieve small, robust, low cost and fast hydrogen micro/nano sensors with high sensitivity and selectivity, the modeling and process optimization was performed. The effect of humidity and the influence of the applied voltage were also studied. The sensor could be tuned to have high sensitivity (105), fast response time (10 seconds) and low energy consumption (19 nW). Finally, a portable hydrogen instrument integrated with a micro sensor, display, sound warning system, and measurement circuitry was fabricated based on the calibration data of the sensor.
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Date Issued: 2008
Identifier: CFE0002478, ucf:47725
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002478

Title: EFFECTS OF TRANSPORT PROPERTIES AND FLAME UNSTEADINESS ON NITROGEN OXIDES EMISSIONS FROM LAMINAR HYDROGEN JET DIFFUSION FLAMES.
Creator: Park, Doyoub, Chen, Ruey-Hung, University of Central Florida
Abstract / Description: Experimental studies on the coupled effects of transport properties and unsteady fluid dynamics have been conducted on laminar, acoustically forced, hydrogen jet diffusion flames diluted by argon and helium. The primary purpose of this research is to determine how the fuel Lewis number and the flow unsteadiness play a combined role in maximum flame temperature and affect NOx emission from jet diffusion flame. The fuel Lewis number is varied by increasing/decreasing the mole fraction of...
Show moreExperimental studies on the coupled effects of transport properties and unsteady fluid dynamics have been conducted on laminar, acoustically forced, hydrogen jet diffusion flames diluted by argon and helium. The primary purpose of this research is to determine how the fuel Lewis number and the flow unsteadiness play a combined role in maximum flame temperature and affect NOx emission from jet diffusion flame. The fuel Lewis number is varied by increasing/decreasing the mole fraction of diluents in the fuel stream. Therefore, maximum flame temperatures and then NOx emission levels were expected to differ for Ar- and He-diluted flames. In an investigation of unsteady flames, two different frequencies (10 and 100 Hz) were applied to observe a behavior of NOx emission levels and flame lengths by changes of unsteady fluid dynamics and transport properties.
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Date Issued: 2005
Identifier: CFE0000646, ucf:46535
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000646

Title: SURFACE CHEMISTRY OF APPLICATION SPECIFIC PADS AND COPPER CHEMICAL MECHANICAL PLANARIZATION.
Creator: Deshpande, Sameer Arun, Seal, Sudipta, University of Central Florida
Abstract / Description: Advances in the interconnection technology have played a key role in the continued improvement of the integrated circuit (IC) density, performance and cost. Copper (Cu) metallization, dual damascenes processing and integration of copper with low dielectric constant material are key issues in the IC industries. Chemical mechanical planarization of copper (Cu-CMP) has emerged as an important process for the manufacturing of ICs. Usually, Cu-CMP process consists of several steps such as the...
Show moreAdvances in the interconnection technology have played a key role in the continued improvement of the integrated circuit (IC) density, performance and cost. Copper (Cu) metallization, dual damascenes processing and integration of copper with low dielectric constant material are key issues in the IC industries. Chemical mechanical planarization of copper (Cu-CMP) has emerged as an important process for the manufacturing of ICs. Usually, Cu-CMP process consists of several steps such as the removal of surface layer by mechanical action of the pad and the abrasive particles, the dissolution of the abraded particles in the CMP solution, and the protection of the recess areas. The CMP process occurs at the atomic level at the pad/slurry/wafer interface, and hence, slurries and polishing pads play critical role in its successful implementation. The slurry for the Cu-CMP contains chemical components to facilitate the oxidation and removal of excess Cu as well as passivation of the polished surface. During the process, these slurry chemicals also react with the pad. In the present study, investigations were carried out to understand the effect of hydrogen peroxide (H2O2) as an oxidant and benzotriazole (BTA) as an inhibitor on the CMP of Cu. Interaction of these slurry components on copper has been investigated using electrochemical studies, x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). In the presence of 0.1M glycine, Cu removal rate was found to be high in the solution containing 5% H2O2 at pH 2 because of the Cu-glycine complexation reaction. The dissolution rate of the Cu was found to increase due to the formation of highly soluble Cu-glycine complex in the presence of H2O2. Addition of 0.01M BTA in the solution containing 0.1M glycine and 5% H2O2 at pH 2 exhibited a reduction in the Cu removal rate due to the formation of Cu-BTA complex on the surface of the Cu further inhibiting the dissolution. XPS and SIMS investigations revealed the formation of such Cu-glycine complex, which help understand the mechanism of the Cu-oxidant-inhibitor interaction during polishing. Along with the slurry, pads used in the Cu-CMP process have direct influence an overall process. To overcome problems associated with the current pads, new application specific pad (ASP) have been developed in collaboration with PsiloQuest Inc. Using plasma enhanced chemical vapor deposition (PECVD) process; surface of such ASP pads were modified. Plasma treatment of a polymer surface results in the formation of various functional groups and radicals. Post plasma treatment such as chemical reduction or oxidation imparts a more uniform distribution of such functional groups on the surface of the polymer resulting in unique surface properties. The mechanical properties of such coated pad have been investigated using nano-indentation technique in collaboration with Dr. Vaidyanathan's research group. The surface morphology and the chemistry of the ASP are studied using scanning electron microcopy (SEM), x-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR) to understand the formation of different chemical species on the surface. It is observed that the mechanical and the chemical properties of the pad top surface are a function of the PECVD coating time. Such PECVD treated pads are found to be hydrophilic and do not require being stored in aqueous medium during the not-in-use period. The metal removal rate using such surface modified polishing pad is found to increase linearly with the PECVD coating time. Overall, this thesis is an attempt to optimize the two most important parameters of the Cu-CMP process viz. slurry and pads for enhanced performance and ultimately reduce the cost of ownership (CoO).
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Date Issued: 2004
Identifier: CFE0000125, ucf:46191
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000125

Title: DETERMINATION OF THE HYDROGEN PEROXIDE CONCENTRATION IN ROTENONE INDUCED DOPAMINERGIC CELLS USING CYCLIC VOLTAMMETRY AND AMPLEX® RED.
Creator: Patel, Kishan, Kim, Yoon, University of Central Florida
Abstract / Description: Parkinson's disease (PD) is a neurodegenerative condition that affects millions of people worldwide. The exact etiology of PD is unknown. However, it is well established that environmental factors contribute to the onset of PD. In particular, chemicals such as the insecticide Rotenone have been shown to increase the death of dopaminergic (DA) neurons by increasing levels of reactive oxygen species (ROS). ROS such as hydrogen peroxide (H2O2) have been shown to be elevated above basal levels in...
Show moreParkinson's disease (PD) is a neurodegenerative condition that affects millions of people worldwide. The exact etiology of PD is unknown. However, it is well established that environmental factors contribute to the onset of PD. In particular, chemicals such as the insecticide Rotenone have been shown to increase the death of dopaminergic (DA) neurons by increasing levels of reactive oxygen species (ROS). ROS such as hydrogen peroxide (H2O2) have been shown to be elevated above basal levels in PD patients. Currently, to measure H2O2 concentrations, a commercially available (Amplex® Red) fluorescent assay is used. However, the assay has limitations: it is not completely specific to hydrogen peroxide and can only measure extracellular ROS concentrations. This research focuses on testing an electrochemical sensor that uses cyclic voltammetry to quantitatively determine concentrations of H2O2 released from a cell culture. The sensor was first tested in normal cell culture conditions. Next, chemical interference was reduced and the sensor was optimized for accuracy by altering protein concentrations in the media. Finally, Rotenone was added to a cell culture to induce H2O2 production. Near real-time measurements of H2O2 were taken using the sensor and comparisons made to the fluorescent assay method. Overall, we are trying to determine if the electrochemical sensor can selectively and quantitatively measure H2O2 released from cells. Being able to track the production, migration and concentration of H2O2 in a cell can help researchers better understand its mechanism of action in cell death and oxidative damage, thus getting closer to finding a cure for PD.
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Date Issued: 2012
Identifier: CFH0004222, ucf:44921
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004222

Title: EXPERIMENTAL ANALYSIS OF THE HYDROGEN SULFIDE ABSORTION PHENOMENA IN BRINE/OIL MIXTURES AS A FUNCTION OF SYSTEM PRESSURE AND H2S CONCENTRATION.
Creator: Zea, Luis, Kumar, Ranganathan, University of Central Florida
Abstract / Description: In underground oil reservoirs, Hydrogen sulfide is usually found coexisting with the oil due to bacteria reduction over a long period of time. The amount of H2S in the oil varies from place to place around the globe. When the oil extraction process begins, the presence of Hydrogen sulfide becomes noticeable as drilling tools, piping and other equipment suffer from sulfide stress cracking, electrochemical corrosion and corrosion fatigue. For this reason, the oil industry invests millions of...
Show moreIn underground oil reservoirs, Hydrogen sulfide is usually found coexisting with the oil due to bacteria reduction over a long period of time. The amount of H2S in the oil varies from place to place around the globe. When the oil extraction process begins, the presence of Hydrogen sulfide becomes noticeable as drilling tools, piping and other equipment suffer from sulfide stress cracking, electrochemical corrosion and corrosion fatigue. For this reason, the oil industry invests millions of dollars per year trying to find better ways to reduce the amount of H2S in oil. An important part of the current investigations deals with brine (sea water)/oil mixtures. The reasons are two-fold: 1) one way of extracting the petroleum from the reservoir is by injecting brine into it and since it has a higher density than oil, the latter will be ejected up to the surface. Taking into account the complex fluid flow occurring within the reservoir it is easy to understand that some brine will also be present as part of the ejected fluid; 2) brine is already present in the reservoir, so independent of the extraction method used, there will be a brine/oil mixture in the ejected flow. When brine and oil have absorbed H2S under pressure in the reservoir and then suffer a decompression during the extraction process, a certain amount of H2S is released from the liquid phase. In order to have a better prediction of how much Hydrogen sulfide can be liberated a good understanding of H2S absorption by these liquids is necessary. The amount of gas a solvent absorbs is a function of pressure, original gas concentration and temperature as described by Henry's Law. The purpose of this thesis is to experimentally analyze how much of the corrosive gas is absorbed into different brine/oil mixtures, and brine and oil, separately. In order to find sufficient data for a thorough analysis, different reservoir simulation scenarios were created. The liquids were mixed from pure brine to pure oil, resulting in 33% and 66% water cuts. Data were obtained at 2 pressures of 20atm and 70atm at room temperature. H2S concentration was also a variable, changing the original gas concentration through different values: 50, 100, and 300ppm. These experiments were conducted in an autoclave system and will better explain the hydrostatic process that occurs inside the reservoir. It was found that throughout all the water cuts, the role that total pressure plays in the absorption phenomena is of less importance as the original H2S concentration is increased. In the same manner it was observed that the highest mass-absorption ratios are always found between 50 and 100ppm and the lowest at 300ppm, this is observed for all water cuts and total pressures. Another important finding was that the ability to absorb the corrosive gas decreases as the original H2S concentration increases and this proves to be true for all water cuts and system pressures. After conducting these different reservoir scenarios, tests were conducted to simulate 300m of the horizontal section of the pipe that connects the head of the well with the platform. This was done with a high pressure 300-meter long loop. It was found that the corrosive gas is absorbed at a higher rate when there is a flow, opposite to a hydrostatic case. Henry's Law constant was identified for each water cut and each pressure, however, the test procedure could not be validated since the gas being studied was not in its pure form. Understanding the absorption phenomena of Hydrogen sulfide in different water cuts will definitely be of great help to the oil industry to make better forecasts of H2S concentrations being ejected from each well.
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Date Issued: 2008
Identifier: CFE0002257, ucf:47824
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002257

Title: HYDROGEN SULFIDE FLUX MEASUREMENTS AND DISPERSION MODELING FROM CONSTRUCTION AND DEMOLITION (C&D) DEBRIS LANDFILLS.
Creator: Eun, Sangho, Reinhart, Debra, University of Central Florida
Abstract / Description: Odor problems are a common complaint from residents living near landfills. Many compounds can cause malodorous conditions. However, hydrogen sulfide (h2s) has been identified as a principal odorous component from construction and demolition (c&d)debris landfills. Although several studies have reported the ambient concentrations of h2s near c&d landfills, few studies have quantified emission rates of h2s. The most widely used and proven technique for measuring gas emission rates from...
Show moreOdor problems are a common complaint from residents living near landfills. Many compounds can cause malodorous conditions. However, hydrogen sulfide (h2s) has been identified as a principal odorous component from construction and demolition (c&d)debris landfills. Although several studies have reported the ambient concentrations of h2s near c&d landfills, few studies have quantified emission rates of h2s. The most widely used and proven technique for measuring gas emission rates from landfills is the flux chamber method. Typically the flux chamber is a cylindrical enclosure device with a spherical top which limits the gas emission area. Pure zero grade air is introduced into the chamber, allowed to mix with emitting gases captured from the landfill surface, and then transported to the exit port where concentrations can be measured. Flux measurements using the flux chamber were performed at five different c&d landfills from june to august, 2003. The flux rates of h2s measured in this research were three to six orders of magnitude lower than the flux rates of methane reported in the literature. In addition to the h2s flux measurements, dispersion modeling was conducted, using the epa dispersion model, industrial source complex short term (iscst3), in order to evaluate impacts on landfill workers and communities around the landfills. The modeling results were analyzed to estimate the potential ground level maximum h2s concentrations for 1-hr and 3-min periods and the frequency (occurrences per year) above the h2s odor detection threshold for each landfill. Odor complaints could be expected from four among five landfills selected for this study, based on 0.5-ppb odor detection threshold.
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Date Issued: 2004
Identifier: CFE0000169, ucf:52837
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000169

Title: Surface Acoustic Wave (SAW) Cryogenic Liquid and Hydrogen Gas Sensors.
Creator: Fisher, Brian, Malocha, Donald, Gong, Xun, Likamwa, Patrick, Richie, Samuel, Youngquist, Robert, University of Central Florida
Abstract / Description: This research was born from NASA Kennedy Space Center's (KSC) need for passive, wireless and individually distinguishable cryogenic liquid and H2 gas sensors in various facilities. The risks of catastrophic accidents, associated with the storage and use of cryogenic fluids may be minimized by constant monitoring. Accidents involving the release of H2 gas or LH2 were responsible for 81% of total accidents in the aerospace industry. These problems may be mitigated by the implementation of a...
Show moreThis research was born from NASA Kennedy Space Center's (KSC) need for passive, wireless and individually distinguishable cryogenic liquid and H2 gas sensors in various facilities. The risks of catastrophic accidents, associated with the storage and use of cryogenic fluids may be minimized by constant monitoring. Accidents involving the release of H2 gas or LH2 were responsible for 81% of total accidents in the aerospace industry. These problems may be mitigated by the implementation of a passive (or low-power), wireless, gas detection system, which continuously monitors multiple nodes and reports temperature and H2 gas presence. Passive, wireless, cryogenic liquid level and hydrogen (H2) gas sensors were developed on a platform technology called Orthogonal Frequency Coded (OFC) surface acoustic wave (SAW) radio frequency identification (RFID) tag sensors. The OFC-SAW was shown to be mechanically resistant to failure due to thermal shock from repeated cycles between room to liquid nitrogen temperature. This suggests that these tags are ideal for integration into cryogenic Dewar environments for the purposes of cryogenic liquid level detection. Three OFC-SAW H2 gas sensors were simultaneously wirelessly interrogated while being exposed to various flow rates of H2 gas. Rapid H2 detection was achieved for flow rates as low as 1ccm of a 2% H2, 98% N2 mixture. A novel method and theory to extract the electrical and mechanical properties of a semiconducting and high conductivity thin-film using SAW amplitude and velocity dispersion measurements were also developed. The SAW device was shown to be a useful tool in analysis and characterization of ultrathin and thin films and physical phenomena such as gas adsorption and desorption mechanisms.?
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Date Issued: 2012
Identifier: CFE0004536, ucf:49258
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004536

hydrogen (5)	+ -
hydrogen peroxide (4)	+ -
Hydrogen Sulfide (3)	+ -
H2S (2)	+ -
Hydrogen (2)	+ -

Hydrogen peroxide (2)	+ -
combustion (2)	+ -
hydrogen sulfide (2)	+ -
liquid hydrogen (2)	+ -
odor (2)	+ -
3D (1)	+ -
AERMOD (1)	+ -
Accelerated durability (1)	+ -
Aeration (1)	+ -
Amperometric (1)	+ -
Amplex Red (1)	+ -
Benzotriazole (1)	+ -
Binding energy (1)	+ -
Bond Formation Energy (1)	+ -
Brine (1)	+ -
Buffering Distance (1)	+ -
Burke-Schumann (1)	+ -
C & D (1)	+ -
C and D (1)	+ -
C&D landfill (1)	+ -
CIGS2 (1)	+ -
Ceria (1)	+ -
Cerium oxide (1)	+ -
Cerium oxide nanoparticles (1)	+ -
Chemical Mechanical Planarization (CMP) (1)	+ -

ETD Collection (28)	+ -
Honors Collection (4)	+ -

University of Central Florida (32)	+ -
Hampton, Michael (5)	+ -
Seal, Sudipta (4)	+ -
Harper, James (3)	+ -
Vasu Sumathi, Subith (3)	+ -

Blair, Richard (2)	+ -
Cho, Hyoung Jin (2)	+ -
Clausen, Christian (2)	+ -
Duranceau, Steven (2)	+ -
Kapat, Jayanta (2)	+ -
Oztek, Muzaffer (2)	+ -
Randall, Andrew (2)	+ -
Reinhart, Debra (2)	+ -
Yestrebsky, Cherie (2)	+ -
Youngquist, Robert (2)	+ -
Zhai, Lei (2)	+ -
Ahmed, Kareem (1)	+ -
Barak, Samuel (1)	+ -
Belfield, Kevin (1)	+ -
Bhattacharya, Aniket (1)	+ -
Blandon Zapata, Juan (1)	+ -
Bolyard, Steven (1)	+ -
Campiglia, Andres (1)	+ -
Chen, Ruey-Hung (1)	+ -
Cherne, Michelle D (1)	+ -
Cho, Hyoung (Joe) (1)	+ -
Chopra, Manoj (1)	+ -
Chow, Louis (1)	+ -
Coffey, Kevin (1)	+ -
Cooper, Charles (1)	+ -

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