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MICROSTRUCTURAL INVESTIGATION OF PRECIPITATION HARDENED CUNI2SI+ZR ALLOYS FOR ROTOR APPLICATIONS
Title
MICROSTRUCTURAL INVESTIGATION OF PRECIPITATION HARDENED CUNI2SI+ZR ALLOYS FOR ROTOR APPLICATIONS.
Creator
Vega-Garcia, Jean-Paul, Sohn, Yong-Ho, University of Central Florida
Abstract / Description
Industrial generator components experience high stresses and electrical fields during their service life. Material integrity is key in guaranteeing component performance. CuNi2SiZr, used as rotor wedges in generators, serve to maintain rotor slot content in place while experiencing high centrifugal stresses and low cycle fatigue during start and stop at elevated temperature. The quality and integrity of this material in service can be directly related to its microstructure, which is...
Show moreIndustrial generator components experience high stresses and electrical fields during their service life. Material integrity is key in guaranteeing component performance. CuNi2SiZr, used as rotor wedges in generators, serve to maintain rotor slot content in place while experiencing high centrifugal stresses and low cycle fatigue during start and stop at elevated temperature. The quality and integrity of this material in service can be directly related to its microstructure, which is determined by the processing procedures of the wedges. In this study, the microstructure development in this material is evaluated to eliminate grain boundary defects by optimizing processing parameters, determining the best temperature/time combination for precipitation hardening, and determining cold work effect on aging parameters. Two chemistries containing Nickel-to-Silicon ratios of 3.2 and 3.8 were selected for analysis. Cast samples were hot extruded, cold worked, and precipitation hardened. Parameters were varied at each processing step. Five different levels of cold work (4, 5, 7, 10 and 13%) were evaluated using 5 different aging temperatures (450, 460, 470, 490 and 500°C). Each processing parametersÂÂÂÂÂÂÂÂ' effect on microstructure and subsequently on hardness, conductivity, and tensile strength was recorded to assess material performance and identify grain boundary defects origination. Finding of this study identified observed grain boundary defects, using Transmission Electron Analysis, as voids/micro-tears. These defects on grain boundary are detrimental to low cycle fatigue, creep rupture and tensile strength properties and important aspects of the material performance. Grain boundary defects were observed at all levels of cold work, however, origination of defects was only observed in grain sizes larger than 50µm. The strengthening phases for the CuNi2Si+Zr alloy system were identified as Ni2Si and Cr3Si. The Nickel-to-Silicon ratio had an evident effect on the electrical conductivity of the material. However, aging benefits were not clearly established between the two Nickel-to-Silicon ratios.
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Date Issued
2010
Identifier
CFE0003350, ucf:48467
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003350
Aging Characteristics of an Aluminum-4.5% Copper-1.5% Magnesium Alloy
Title
Aging Characteristics of an Aluminum-4.5% Copper-1.5% Magnesium Alloy.
Creator
Sulouff, Robert E., Smith, William F., Engineering
Abstract / Description
Florida Technological University College of Engineering Thesis; The effects of quenching conditions, single-step and two-step aging treatments on the tensile properties of an AL-4.5%Cu-1.5%Mg alloy has been investigated. Results indicate that two distinctly different precipitates of GPB and S' form during aging. Single-step aging at 140°C, 160°C and 190°C indicated that 24 hours at 160°C produced optimum strength (67 ksi UTS). Two-step aging for 3 days at 140°C plus 190°C resulted in a...
Show moreFlorida Technological University College of Engineering Thesis; The effects of quenching conditions, single-step and two-step aging treatments on the tensile properties of an AL-4.5%Cu-1.5%Mg alloy has been investigated. Results indicate that two distinctly different precipitates of GPB and S' form during aging. Single-step aging at 140°C, 160°C and 190°C indicated that 24 hours at 160°C produced optimum strength (67 ksi UTS). Two-step aging for 3 days at 140°C plus 190°C resulted in a slight increase in strength over single step aging at 190°C. Slow (oil) quenching as well as direct quenching improved the tensile properties when aged at 190°C. Reversion occurred slowly over the temperature range 250°C to 350°C.
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Date Issued
1977
Identifier
CFR0011985, ucf:53095
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFR0011985
MECHANICAL PROPERTIES OF CARBON NANOTUBE / METAL COMPOSITES
Title
MECHANICAL PROPERTIES OF CARBON NANOTUBE / METAL COMPOSITES.
Creator
Sun, Ying, Chen, Quanfang, University of Central Florida
Abstract / Description
Carbon nanotubes (CNTs) have captured a great deal of attention worldwide since their discovery in 1991. CNTs are considered to be the stiffest and strongest material due to their perfect atomic arrangement and intrinsic strong in-plane sp2ÂÂ--sp2 covalent bonds between carbon atoms. In addition to mechanical properties, CNTs have also shown exceptional chemical, electrical and thermal properties. All these aspects make CNTs promising candidates in the development of novel...
Show moreCarbon nanotubes (CNTs) have captured a great deal of attention worldwide since their discovery in 1991. CNTs are considered to be the stiffest and strongest material due to their perfect atomic arrangement and intrinsic strong in-plane sp2ÂÂ--sp2 covalent bonds between carbon atoms. In addition to mechanical properties, CNTs have also shown exceptional chemical, electrical and thermal properties. All these aspects make CNTs promising candidates in the development of novel multi-functional nanocomposites. Utilizing CNTs as fillers to develop advanced nanocomposites still remains a challenge, due to the lack of fundamental understanding of both material processing at the nanometer scale and the resultant material properties. In this work, a new model was developed to investigate the amount of control specific parameters have on the mechanical properties of CNT composites. The new theory can be used to guide the development of advanced composites using carbon nanotubes, as well as other nano-fibers, with any matrices (ceramic, metal, or polymer). Our study has shown that the varying effect based on changes in CNT dimensions and concentration fit the model predictions very well. Metallic CNT composites using both single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT), have been developed through a novel electrochemical co-deposition process. Copper and nickel matrix composites were developed by using pulse-reverse electrochemical co-deposition. Uniaxial tensile test results showed that a more than 300% increase in strength compared to that of the pure metal had been achieved. For example, the ultimate tensile strength of Ni/CNTs composites reached as high as about 2GPa. These are best experimental results ever reported within this field. The mechanical results are mainly attributed to the good interfacial bonding between the CNTs and the metal matrices and good dispersion of carbon nanotubes within the matrices. Experimental results have also shown that the strength is inversely dependent on the diameter of carbon nanotubes. In addition to the mechanical strength, carbon nanotube reinforced metallic composites are excellent multifunctional materials in terms of electrical and thermal conduction. The electrical resistivity of carbon nanotube/copper composites produces electrical resistivity of about 1.0~1.2 x10-6ohm-cm, which is about 40% less than the pure copper. The reduced electrical resistivity is also attributed to the good interfacial bonding between carbon nanotubes and metal matrices, realized by the electrochemical co-deposition.
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Date Issued
2010
Identifier
CFE0003144, ucf:48652
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003144
Aging Characteristics of Al-4.5%Cu-1.4%Mg-0.5%Ag
Title
Aging Characteristics of Al-4.5%Cu-1.4%Mg-0.5%Ag.
Creator
White, James Kelly, Smith, William F., Engineering
Abstract / Description
Florida Technological University College of Engineering Thesis; The effects of single-step and two-step aging treatments on the tensile properties of an A1-4.5%Cu-1.4%Mg- 0.5%Ag alloy have been investigated. Results showed that a maximum ultimate tensile strength of 75 ksi can be attained by single-step aging 24 hr at 170°C. The two-step aging treatments consisting of first aging one week at 80°C followed by aging at 160° and 190°C led to lower strength properties than simple one-step aging....
Show moreFlorida Technological University College of Engineering Thesis; The effects of single-step and two-step aging treatments on the tensile properties of an A1-4.5%Cu-1.4%Mg- 0.5%Ag alloy have been investigated. Results showed that a maximum ultimate tensile strength of 75 ksi can be attained by single-step aging 24 hr at 170°C. The two-step aging treatments consisting of first aging one week at 80°C followed by aging at 160° and 190°C led to lower strength properties than simple one-step aging. Reversion treatments applied to fully age-hardened alloy resulted in an almost progressive loss of strength in the 250° to 375° range.
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Date Issued
1977
Identifier
CFR0003473, ucf:53038
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFR0003473
First Principle Studies of Cu-Carbon Nanotube Hybrid Structures with Emphasis on the Electronic Structures and the Transport Properties
Title
First Principle Studies of Cu-Carbon Nanotube Hybrid Structures with Emphasis on the Electronic Structures and the Transport Properties.
Creator
Yang, Chengyu, Chen, Quanfang, Leuenberger, Michael, Coffey, Kevin, Ishigami, Marsahir, Fang, Jiyu, University of Central Florida
Abstract / Description
Carbon nanotubes have been regarded as ideal building blocks for nanoelectronics and multifunctional nanocomposites due to their exceptional strength, stiffness, flexibility, as well as their excellent electrical properties. However, carbon nanotube itself has limitations to fulfill the practical application needs: 1) an individual carbon nanotube has a low density of states at the Fermi level, and thus its conductivity is only comparable to moderate metals but lower than that of copper. 2)...
Show moreCarbon nanotubes have been regarded as ideal building blocks for nanoelectronics and multifunctional nanocomposites due to their exceptional strength, stiffness, flexibility, as well as their excellent electrical properties. However, carbon nanotube itself has limitations to fulfill the practical application needs: 1) an individual carbon nanotube has a low density of states at the Fermi level, and thus its conductivity is only comparable to moderate metals but lower than that of copper. 2) Metallic and semiconducting nanotubes are inherently mixed together from the synthesis, and the selection/separation is very difficult with very low efficiency. 3) Carbon nanotubes alone cannot be used in practical application and a bonding material is normally needed as the join material for actual devices. In this work, we fundamentally explored the possibility that metals (Cu, Al) could tailor carbon nanotube's electronic structure and even transit it from semiconducting to metallic, thus skipping the selection between the metallic and the semiconducting CNTs. We also found out a novel way to enhance a semiconducting CNT system's conductance even better than that of a metallic CNT system. All these researches are done under density functional theory (DFT) frame in conjunction with non-equilibrium Green functions (NEGF).At first we studied the adsorbed copper's influence on the electronic properties of CNT (10, 0) and CNT (5, 5). Results indicate that both the Density of States (DOS) and the transmission coefficients of CNT (5,5) /Cu have been increased. For CNT (10,0)/Cu, the band gap has been shrank, which means the improved conducting properties by the incorporation of copper . As a further case, semiconductor SWCNT (10, 0) with more adsorbed copper chains outside has been studied. 1, 4, 5 and 6 Cu chains have been added onto the carbon nanotube (10,0), and the adsorption of 6 Cu chains finally lead to the transform of the system from semiconducting to metallic. Considering the confining effect, the case that Cu filled into CNT (10, 0) is also studied. It is found that the filled copper chains could modify the system to be metallic more efficiently than the adsorbed Cu chain. Similarly, Al adsorbed on CNT (10, 0) is also studied, and it is found that Al has a better efficiency than copper in tuning the semiconducting CNT to metallic. The existing chemical bonds between the CNT and Al atoms may account for this higher efficiency. In addition, the resultant conductivity of the Al/CNT system is better than that of Cu/CNT system. The Cu/CNT (5,5)+Cu/Cu junction, as another realistic device setup, has been studied in terms of the conductance. The results show that the incorporation of Cu would enhance the conductance of the Cu/CNT/Cu system due to the interaction between Cu and the CNT.
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Date Issued
2013
Identifier
CFE0005280, ucf:50561
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005280
Novel copper loaded core-shell silica nanoparticles with improved copper bio-availability : Synthesis, characterization and study of antibacterial properties
Title
Novel copper loaded core-shell silica nanoparticles with improved copper bio-availability : Synthesis, characterization and study of antibacterial properties.
Creator
Maniprasad, Pavithra, Santra, Swadeshmukul, Self, William, Naser, Saleh, University of Central Florida
Abstract / Description
A novel core-shell silica based antimicrobial nanoparticle was synthesized. The St(&)#246;ber silica shell has been engineered to accommodate copper. Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiNP) involves preparation of base-hydrolyzed St(&)#246;ber silica (")seed(") particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. Scanning electron microscopy and transmission electron microscopy showed monodispersed, spherical...
Show moreA novel core-shell silica based antimicrobial nanoparticle was synthesized. The St(&)#246;ber silica shell has been engineered to accommodate copper. Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiNP) involves preparation of base-hydrolyzed St(&)#246;ber silica (")seed(") particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. Scanning electron microscopy and transmission electron microscopy showed monodispersed, spherical shaped nanoparticles with smooth surface morphology. Characterization of particle size distribution in solution by the Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). Antibacterial efficacy of C-S CuSiNP was evaluated against E.coli and B.subtilis using Cu hydroxide ((")Insoluble(") Cu compound) and copper sulfate as positive control and silica (")seed(") particles (without Cu loading) as negative control. Minimum Inhibitory Concentration (MIC) of C-S CuSiNP was evaluated by measuring the fluorescent intensity of resorufin to determine the decrease in viable cells with increase in copper concentration in C-S CuSiNP. The MIC value of C-S CuSiNP against both E.coli and B.subtilis was estimated to be 4.9 ppm. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. Antibacterial study clearly shows that C-S CuSiNP is more effective than insoluble Cu hydroxide particles and copper sulfate at equivalent metallic Cu concentration, suggesting more soluble Cu in C-S CuSiNP material due to its core-shell design.
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Date Issued
2011
Identifier
CFE0004479, ucf:49300
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004479
THE EFFECTS OF PHOSPHATE AND SILICATE INHIBITORS ON SURFACE ROUGHNESS AND COPPER RELEASE IN WATER DISTRIBUTION SYSTEMS
Title
THE EFFECTS OF PHOSPHATE AND SILICATE INHIBITORS ON SURFACE ROUGHNESS AND COPPER RELEASE IN WATER DISTRIBUTION SYSTEMS.
Creator
MacNevin, David, Taylor, James, University of Central Florida
Abstract / Description
The effects of corrosion inhibitors on water quality and the distribution system were studied. This dissertation investigates the effect of inhibitors on iron surface roughness, copper surface roughness, and copper release. Corrosion inhibitors included blended poly/ortho phosphate, sodium orthophosphate, zinc orthophosphate, and sodium silicate. These inhibitors were added to a blend of surface water, groundwater, and desalinated brackish water. Surface roughness of galvanized iron, unlined...
Show moreThe effects of corrosion inhibitors on water quality and the distribution system were studied. This dissertation investigates the effect of inhibitors on iron surface roughness, copper surface roughness, and copper release. Corrosion inhibitors included blended poly/ortho phosphate, sodium orthophosphate, zinc orthophosphate, and sodium silicate. These inhibitors were added to a blend of surface water, groundwater, and desalinated brackish water. Surface roughness of galvanized iron, unlined cast iron, lined cast iron, and polyvinyl chloride was measured using pipe coupons exposed for three months. Roughness of each pipe coupon was measured with an optical surface profiler before and after exposure to inhibitors. For most materials, inhibitor did not have a significant effect on surface roughness; instead, the most significant factor determining the final surface roughness was the initial surface roughness. Coupons with low initial surface roughness tended to have an increase in surface roughness during exposure, and vice versa, implying that surface roughness tended to regress towards an average or equilibrium value. For unlined cast iron, increased alkalinity and increased temperature tended to correspond with increases in surface roughness. Unlined cast iron coupons receiving phosphate inhibitors were more likely to have a significant change in surface roughness, suggesting that phosphate inhibitors affect stability of iron pipe scales. Similar roughness data collected with new copper coupons showed that elevated orthophosphate, alkalinity, and temperature were all factors associated with increased copper surface roughness. The greatest increases in surface roughness were observed with copper coupons receiving phosphate inhibitors. Smaller increases were observed with copper coupons receiving silicate inhibitor or no inhibitor. With phosphate inhibitors, elevated temperature and alkalinity were associated with larger increases in surface roughness and blue-green copper (II) scales.. Otherwise a compact, dull red copper (I) scale was observed. These data suggest that phosphate inhibitor addition corresponds with changes in surface morphology, and surface composition, including the oxidation state of copper solids. The effects of corrosion inhibitors on copper surface chemistry and cuprosolvency were investigated. Most copper scales had X-ray photoelectron spectroscopy binding energies consistent with a mixture of Cu2O, CuO, Cu(OH)2, and other copper (II) salts. Orthophosphate and silica were detected on copper surfaces exposed to each inhibitor. All phosphate and silicate inhibitors reduced copper release relative to the no inhibitor treatments, keeping total copper below the 1.3 mg/L MCLG for all water quality blends. All three kinds of phosphate inhibitors, when added at 1 mg/L as P, corresponded with a 60% reduction in copper release relative to the no inhibitor control. On average, this percent reduction was consistent across varying water quality conditions in all four phases. Similarly when silicate inhibitor was added at 6 mg/L as SiO2, this corresponded with a 25-40% reduction in copper release relative to the no inhibitor control. Hence, on average, for the given inhibitors and doses, phosphate inhibitors provided more predictable control of copper release across changing water quality conditions. A plot of cupric ion concentration versus orthophosphate concentration showed a decrease in copper release consistent with mechanistic control by either cupric phosphate solubility or a diffusion limiting phosphate film. Thermodynamic models were developed to identify feasible controlling solids. For the no inhibitor treatment, Cu(OH)2 provided the closest prediction of copper release. With phosphate inhibitors both Cu(OH)2 and Cu(PO4)·2H2O models provided plausible predictions. Similarly, with silicate inhibitor, the Cu(OH)2 and CuSiO3·H2O models provided plausible predictions.
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Date Issued
2008
Identifier
CFE0002001, ucf:47621
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002001
USING ELECTROCHEMICAL MONITORING TO PREDICT METAL RELEASE IN DRINKING WATER DISTRIBUTION SYSTEMS
Title
USING ELECTROCHEMICAL MONITORING TO PREDICT METAL RELEASE IN DRINKING WATER DISTRIBUTION SYSTEMS.
Creator
Vaidya, Rajendra, Taylor, James, University of Central Florida
Abstract / Description
ABSTRACT Corrosion of distribution system piping and home plumbing materials is a major concern in the water community. Iron release adverse affects aesthetic water quality and the release of copper and lead is regulated by the Lead and Copper rule (LCR) and can adversely affect consumer health. Corrosion control is typically done by pH regulation and/or addition of corrosion inhibitors. Monitoring of corrosion control is typically done after the fact by monitoring metal release, functional...
Show moreABSTRACT Corrosion of distribution system piping and home plumbing materials is a major concern in the water community. Iron release adverse affects aesthetic water quality and the release of copper and lead is regulated by the Lead and Copper rule (LCR) and can adversely affect consumer health. Corrosion control is typically done by pH regulation and/or addition of corrosion inhibitors. Monitoring of corrosion control is typically done after the fact by monitoring metal release, functional group concentration of the selected chemical species or water quality. Hence, the associated laboratory analyses create a significant delay prior to the assessment of corrosion in drinking water systems. As corrosion in drinking water systems is fundamentally an electrochemical process, measurement of the electrical phenomena associated with corrosion can be use for real-time corrosion monitoring. This dissertation focuses on using parameters associated with electrochemical corrosion monitoring (EN) measurements in a field facility to predict and control the release of Iron, Copper and Lead in finished waters produced from ground, surface and saline sources with and without usage of corrosion inhibitors. EN data has not been used previously to correlate water quality and metal release; hence the use of EN data for corrosion control in drinking water systems has not been developed or demonstrated. Data was collected over a one year period from a large field facility using finished waters that are distributed to each of the fourteen pilot distribution systems (PDSs), corrosion loops and Nadles each. The PDSs have been built from aged pipes taken from existing distribution systems and contain links of PVC, lined cast Iron, unlined cast Iron and galvanized Steel pipe. The effluent for each PDS was split in two parts. One was delivered to the corrosion loops which are made from coiled copper pipe with lead-tin coupon inserted inside each loop and the other was delivered to the Nadles which housed the EN probes with electrodes for Fe or Cu or Pb-Sn. Finished water quality was monitored in and out of each PDS and total and dissolved Copper and Lead were monitored out of each corrosion loop. Photographs, scanning electron microscope (SEM) micrographs and energy disruptive x-ray spectroscopy (EDAX) conducted on all EN electrodes. EN electrodes showed dark brown to blackish voluminous scales for Fe, and EDAX revealed occurrence of two scales in distinct areas for all Fe electrodes; one comprised of porous, spongy looking structures and scales with more Fe content where the other had denser and more compact scales richer in Ca and P or Si. Cu electrodes had an orange to dark brown thin scale with blue green spots. Small pits were consistently observed mostly in the centre of such blue green spots which were identified as copper carbonates. The Pb electrodes visually showed a thin shiny transparent film with a surface very similar to the unexposed electrodes. Numerous pits were visually for pH controls and not seen for inhibitors; but SEM revealed that all electrodes had pits but the inhibitors reduced number and size of pits compared with pH controls. Thin hexagonal hydrocerussite plates were observed to occur in distinct growth areas and the presence of P or Si inhibitor seemed to increase the occurrence of hydrocerussite. Both Fe & Pb release were mostly in the particulate form while Cu release was mostly in the dissolved form. Total and dissolved Fe, Cu and Pb release models using EN parameters were developed by nonlinear regression. Fe release increased with localized corrosion (PF) and the EN model predicts that Fe release can be effectively controlled to the same degree by pH elevation or inhibitors. Cu release increased with general corrosion (LPRCR) and was also influenced by localized corrosion (ECNCR). However general corrosion was more significant for copper release which was mostly in the dissolved form. Pb release was depended on both general corrosion (LPRCR & HMCR) and localized corrosion (PF). The EN models predict that both Cu and Pb release is highest for pH control and all inhibitors reduced Cu and Pb release, which is consistent with the data. Inhibitors ranked by increasing effectiveness for reducing both Cu and Pb release are pH elevation, Si, ZOP, OP and BOP. EN monitoring is faster and less labor intensive than water quality monitoring and represents a significant advance for controlling metal release in drinking water distribution systems. The EN models were found to be comparable to water quality models developed from this study for metal release, and since EN is a real-time technique it offers a tremendous advantage over traditional water quality sampling techniques. Remote access of EN monitoring equipment is possible and the system requires little to no maintenance with the exception of a power supply or battery. The rapid turn around of corrosion rates from EN can be used to estimate metal release in drinking water proactively and mitigating measures can be implemented before the full adverse impacts are realized.
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Date Issued
2007
Identifier
CFE0001953, ucf:47430
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001953
PRODUCTION, CONTROL AND ACTUATION OF MICRON-SIZED PARTICLES IN AMICROFLUIDIC T-JUNCTION
Title
PRODUCTION, CONTROL AND ACTUATION OF MICRON-SIZED PARTICLES IN AMICROFLUIDIC T-JUNCTION.
Creator
Wilson, James, Kumar, Ranganathan, University of Central Florida
Abstract / Description
This research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micro]m, from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40degC-50degC. The...
Show moreThis research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micro]m, from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40degC-50degC. The solidification mechanism is referred to as Temperature Induced Forming and is described by polymeric bridges formed between nanoparticles in suspension at elevated temperatures, resulting in a solid structure. The polymer network results from the ionization of alumina at elevated temperatures whereby polymeric binders adhere to newly formed charged sites on the alumina particle. This study aims to investigate the aspects of manufacturing microstructures in microfluidic Tjunctions, droplet morphology, size and frequency of production. Preliminary low solid concentration experiments (1%-10% volume concentration of alumina in H2O) have indicated solidification and a regression in droplet diameter when heated near the saturation temperature of the water used to disperse the particles. The microstructures from this solidification process are uniform and are estimated to be 30 [micro]m in size.
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Date Issued
2013
Identifier
CFH0004387, ucf:44996
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004387
Comparative nutrient removal with innovative green soprtion media for groundwater and stormwater co-treatment
Title
Comparative nutrient removal with innovative green soprtion media for groundwater and stormwater co-treatment.
Creator
Wen, Dan, Chang, Ni-bin, Nam, Boo Hyun, Kibler, Kelly, Wanielista, Martin, Zheng, Qipeng, University of Central Florida
Abstract / Description
As indicated by the National Academy of Engineering, the understanding of nitrogen cycle has been deemed as one of 14 grand challenges in engineering of the 21st century. Due to rapid population growth and urbanization, the stormwater runoff increased in quantity as well as its nutrient concentrations, which may trigger serious environmental issues such as eutrophication in aquatic systems and ecosystem degradation. This study focuses on stormwater and groundwater quality control via...
Show moreAs indicated by the National Academy of Engineering, the understanding of nitrogen cycle has been deemed as one of 14 grand challenges in engineering of the 21st century. Due to rapid population growth and urbanization, the stormwater runoff increased in quantity as well as its nutrient concentrations, which may trigger serious environmental issues such as eutrophication in aquatic systems and ecosystem degradation. This study focuses on stormwater and groundwater quality control via Biosorption Activated Media (BAM) which can be applied to enhance the nutrient removal potential as an emerging Best Management Practices (BMPs). BAM was tested in this study with respect to two changing environmental factors including the presence of toxins such as copper and the addition of carbon sources that may affect the removal effectiveness. In addition, the impacts on microbial ecology in BAM within the nitrification and denitrification processes due to those changing environmental conditions were explored through the identification of microbial population dynamics under different environmental conditions. To further enhance the recovery and reuse of the adsorbed ammonia as possible soil amendment or even fertilizer, a new media called Iron Filing Green Environmental Media (IFGEM) was developed based on BAM, with the inclusion of iron filings as a key component for nitrate reduction. The functionality of IFGEM was analyzed through a serious column studies with respect to several key factors, including varying influent nutrient concentrations, pH values, and temperature. The results of the column studies demonstrate promising nutrient removal and recovery potential simultaneously under changing factors.
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Date Issued
2018
Identifier
CFE0007770, ucf:52394
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007770
Mixed Valence Copper(Cu)/Silica Nanocomposite: Synthesis, Characterization and Systematic Antimicrobial Studies
Title
Mixed Valence Copper(Cu)/Silica Nanocomposite: Synthesis, Characterization and Systematic Antimicrobial Studies.
Creator
Young, Mikaeel, Santra, Swadeshmukul, Self, William, Moore, Sean, University of Central Florida
Abstract / Description
Copper (Cu) compounds are widely used as effective agricultural bactericides. Continuous use of these materials has led to Cu accumulation in soil over time. The United States Environmental Protection Agency (US EPA) is concerned about potential Cu contamination in the environment. Improving biocidal efficacy of Cu is an attractive alternative, allowing reduction of Cu amount per application. In this research, we focused on making water-soluble mixed-valence Copper/Silica composite nanogel ...
Show moreCopper (Cu) compounds are widely used as effective agricultural bactericides. Continuous use of these materials has led to Cu accumulation in soil over time. The United States Environmental Protection Agency (US EPA) is concerned about potential Cu contamination in the environment. Improving biocidal efficacy of Cu is an attractive alternative, allowing reduction of Cu amount per application. In this research, we focused on making water-soluble mixed-valence Copper/Silica composite nanogel (CuSiNG) material. The objective is to improve the efficacy of Cu by manipulating Cu valence states. It has been shown in the literature that Cu (0) and Cu (I) states are more potent that Cu (II) states in terms of their antimicrobial efficacy. It is hypothesized that mixed valence Cu will exhibit improved efficacy over Cu (II). A water-soluble mixed valence Cu/silica nanogel (MV-CuSiNG) composite has been synthesized and characterized. Structure, morphology, crystallinity and composition of the MV-CuSiNG material was characterized using High-Resolution Transmission Electron Microscopy (HRTEM), HRTEM Selected Area Electron Diffraction (SAED) and X-ray Photoelectron Spectroscopy (XPS). Amount of Cu loading in MV-CuSiNG composite material was estimated by Atomic Absorption Spectroscopy (AAS). To confirm presence of Cu (I) in the MV-CuSiNG material, Neocuproine (Nc, a Cu (I) specific chelator) assay was used. Antimicrobial efficacy of MV-CuSiNG and CuSiNG was evaluated against X.alfalfae, B.subtilis and E.coli using Kocide(&)#174; 3000 ((")Insoluble Cu (II)(") compound), Copper sulfate ((")Soluble Cu (II)(") compound) and Cuprous chloride (Copper (I) compound) as positive controls and silica (")seed(") particles (without Cu loading) as negative control. Antimicrobial studies included observing bacterial growth inhibition and determining the Minimum Inhibitory Concentration (MIC). Improved antimicrobial efficacy was observed in MV-CuSiNG when compared to CuSiNG and other controls. For the assessment of plant safety of MV-CuSiNG and CuSiNG materials, phytotoxicity studies were conducted using Vinca sp and Hamlin orange under environmental conditions. It was observed that MV-CuSiNG material was safe to plants at commercially used (standard) spray application rate.
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Date Issued
2013
Identifier
CFE0005282, ucf:50550
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005282
EFFECTS OF SOURCE WATER BLENDING FOLLOWING TREATMENT WITH SODIUM SILICATE AS A CORROSION INHIBITOR ON METAL RELEASE WITHIN A WATER DISTRIBUTION SYSTEM
Title
EFFECTS OF SOURCE WATER BLENDING FOLLOWING TREATMENT WITH SODIUM SILICATE AS A CORROSION INHIBITOR ON METAL RELEASE WITHIN A WATER DISTRIBUTION SYSTEM.
Creator
Lintereur, Phillip, Duranceau, Steven, University of Central Florida
Abstract / Description
A study was conducted to investigate and quantify the effects of corrosion inhibitors on metal release within a pilot distribution system while varying the source water. The pilot distribution system consisted of pre-existing facilities from Taylor et al (2005). Iron, copper, and lead release data were collected during four separate phases of operation. Each phase was characterized by the particular blend ratios used during the study. A blended source water represented a water that had been...
Show moreA study was conducted to investigate and quantify the effects of corrosion inhibitors on metal release within a pilot distribution system while varying the source water. The pilot distribution system consisted of pre-existing facilities from Taylor et al (2005). Iron, copper, and lead release data were collected during four separate phases of operation. Each phase was characterized by the particular blend ratios used during the study. A blended source water represented a water that had been derived from a consistent proportion of three different source waters. These source waters included (1) surface water treated through enhanced coagulation/sedimentation/filtration, (2) conventionally treated groundwater, and (3) finished surface water treated using reverse osmosis membranes. The corrosion inhibitors used during the study were blended orthophosphate (BOP), orthophosphate (OP), zinc orthophosphate (ZOP), and sodium silicate (Si). This document was intended to cite the findings from the study associated with corrosion treatment using various doses of sodium silicate. The doses were maintained to 3, 6, and 12 mg/L as SiO2 above the blend-dependent background silica concentration. Sources of iron release within the pilot distribution system consisted of, in the following order of entry, (1) lined cast iron, (2) un-lined cast iron, and (3) galvanized steel. Iron release data from these materials was not collected for each individual iron source. Instead, iron release data represented the measurement of iron upon exposure to the pilot distribution system in general. There was little evidence to suggest that iron release was affected by sodium silicate. Statistical modeling of iron release suggested that iron release could be described by the water quality parameters of alkalinity, chlorides, and pH. The R2 statistic implied that the model could account for only 36% of the total variation within the iron release data set (i.e. R2 = 0.36). The model implies that increases in alkalinity and pH would be expected to decrease iron release on average, while an increase in chlorides would increase iron release. The surface composition of cast iron and galvanized steel coupons were analyzed using X-ray photoelectron spectroscopy (XPS). The surface analysis located binding energies consistent with Fe2O3, Fe3O4, and FeOOH for both cast iron and galvanized steel. Elemental scans detected the presence of silicon as amorphous silica; however, there was no significant difference between scans of coupons treated with sodium silicate and coupons simply exposed to the blended source water. The predominant form of zinc found on the galvanized steel coupons was ZnO. Thermodynamic modeling of the galvanized steel system suggested that zinc release was more appropriately described by Zn5(CO3)2(OH)6. The analysis of the copper release data set suggested that treatment with sodium silicate decreased copper release during the study. On average the low, medium, and high doses decreased copper release, when compared to the original blend source water prior to sodium silicate addition, by approximately 20%, 30%, and 50%, respectively. Statistical modeling found that alkalinity, chlorides, pH, and sodium silicate dose were significant variables (R2 = 0.68). The coefficients of the model implied that increases in pH and sodium silicate dose decreased copper release, while increases in alkalinity and chlorides increased copper release. XPS for copper coupons suggested that the scale composition consisted of Cu2O, CuO, and Cu(OH)2 for both the coupons treated with sodium silicate and those exposed to the blended source water. Analysis of the silicon elemental scan detected amorphous silica on 3/5 copper coupons exposed to sodium silicate. Silicon was not detected on any of the 8 control coupons. This suggested that sodium silicate inhibitor varied the surface composition of the copper scale. The XPS results seemed to be validated by the visual differences of the copper coupons exposed to sodium silicate. Copper coupons treated with sodium silicate developed a blue-green scale, while control coupons were reddish-brown. Thermodynamic modeling was unsuccessful in identifying a controlling solid that consisted of a silicate-based cupric solid. Lead release was generally decreased when treated with sodium silicate. Many of the observations were recorded below the detection limit (1 ppb as Pb) of the instrument used to measure the lead concentration of the samples during the study. The frequency of observations below the detection limit tended to increase as the dose of sodium silicate increased. An accurate quantification of the effect of sodium silicate was complicated by the observations recorded below detection limit. If the lead concentration of a sample was below detection limit, then the observation was recorded as 1 ppb. Statistical modeling suggested that temperature, alkalinity, chlorides, pH, and sodium silicate dose were important variables associated with lead release (R2 = 0.60). The exponents of the non-linear model implied that an increase in temperature, alkalinity, and chlorides increased lead release, while an increase in pH and sodium silicate dose were associated with a decrease in lead release. XPS surface characterization of lead coupons indicated the presence of PbO, PbO2, PbCO3, and Pb3(OH)2(CO3)2. XPS also found evidence of silicate scale formation. Thermodynamic modeling did not support the possibility of a silicate-based lead controlling solid. A solubility model assuming Pb3(OH)2(CO3)2 as the controlling solid was used to evaluate lead release data from samples in which lead coupons were incubated for long stagnation times. This thermodynamic model seemed to similarly describe the lead release of samples treated with sodium silicate and samples exposed to the blended source water. The pH of each sample was similar, thus sodium silicate, rather than the corresponding increase in pH, would appear to be responsible if a difference had been observed. During the overall study, the effects of BOP, OP, ZOP, and Si corrosion inhibitors were described by empirical models. Statistically, the model represented the expected value, or mean average, function. If these models are to be used to predict a dose for copper release, then the relationship between the expected value function and the 90th percentile must be approximated. The USEPA Lead and Copper Rule (LCR) regulates total copper release at an action level of 1.3 mg/L. This action level represents a 90th percentile rather than a mean average. Evaluation of the complete copper release data set suggested that the standard deviation was proportional to the mean average of a particular treatment. This relationship was estimated using a linear model. It was found that most of the copper data sub-sets (represented by a given phase, inhibitor, and dose) could be described by a normal distribution. The information obtained from the standard deviation analysis and the normality assumption validated the use of a z-score to relate the empirical models to the estimated 90th percentile observations. Since an analysis of the normality and variance (essentially contains the same information as the standard deviation) are required to assess the assumptions associated with an ANOVA, an ANOVA was performed to directly compare the effects of the inhibitors and corresponding doses. The findings suggested that phosphate-based inhibitors were consistently more effective than sodium silicate when comparing the same treatment levels (i.e. doses). Among the phosphate-based inhibitors, the effectiveness of each respective treatment level was inconsistent (i.e. there was no clear indication that any one phosphate-based inhibitor was more effective than the other). As the doses increased for each inhibitor, the results generally suggested that there was a corresponding tendency for copper release to decrease.
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Date Issued
2008
Identifier
CFE0002383, ucf:47737
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002383
SLURRY CHEMISTRY EFFECTS ON COPPER CHEMICAL MECHANICAL PLANARIZATION
Title
SLURRY CHEMISTRY EFFECTS ON COPPER CHEMICAL MECHANICAL PLANARIZATION.
Creator
Luo, Ying, Desai, Vimal, University of Central Florida
Abstract / Description
ABSTRACTChemical-mechanical Planarization (CMP) has emerged as one of the fastest-growing processes in the semiconductor manufacturing industry, and it is expected to show equally explosive growth in the future (Braun, 2001). The development of CMP has been fueled by the introduction of copper interconnects in microelectronic devices. Other novel applications of CMP include the fabrications of microelectromechanical systems (MEMS), advanced displays, three dimensional systems, and so on ...
Show moreABSTRACTChemical-mechanical Planarization (CMP) has emerged as one of the fastest-growing processes in the semiconductor manufacturing industry, and it is expected to show equally explosive growth in the future (Braun, 2001). The development of CMP has been fueled by the introduction of copper interconnects in microelectronic devices. Other novel applications of CMP include the fabrications of microelectromechanical systems (MEMS), advanced displays, three dimensional systems, and so on (Evans, 2002). CMP is expected to play a key role in the next-generation micro- and nanofabrication technologies (Singh, et al., 2002).Despite the rapid increase in CMP applications, the fundamental understanding of the CMP process has been lacking, particularly the understanding of the wafer-slurry-pad interactions that occur during the CMP process. Novel applications of CMP are expected to expand to materials that are complex chemically and fragile mechanically. Thus, fundamental understanding and improvement of slurry design for CMP is the key to the development of sophisticated next-generation CMP processes.Slurry performance for CMP can be determined by several output parameters including removal rate, global planarity, surface topography, and surface defectivity. To achieve global planarity, it is essential to form a very thin passivating surface layer (<2 nm) that is subsequently removed by the mechanical component of the slurry (Kaufman et al., 1991) or by combined chemo-mechanical effects (Tamboli, 2000). Chemical additives like hydrogen peroxide (H2O2), potassium ferricyanide, and ferric chloride are added to slurries as oxidizers in order to form a desirable surface layer. Other chemical additives such as inhibitors (e.g. benzotriazole) and complexing agents (e.g. ammonia) are added to the copper slurry in order to modify the oxide layer. That the removal rate of the thin surface layer is greater at the highest regions of the wafer surface than at the lowest regions leads to surface planarity.In this study, various complexing agents and inhibitors are combined to form slurry chemistry for copper CMP processing in H2O2 based slurries at pH values ranging from 2 to 10. Two complexing agents (glycine and Ethylenediamine) and one inhibitor (3-amino-1, 2, 4-triazole) were selected as slurry constituents for detailed chemical synergistic effect study because they showed good materials removal and surface planarity performances.To understand the fundamental mechanisms involved in copper CMP process with the afore-mentioned slurry chemical formations, various techniques, such as electrochemical testing techniques (including potentiodynamic polarization and electrochemical impedance spectroscopy), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM), were applied. As a result, guidelines for optimized slurry chemical formulation were arrived at and the possible mechanisms of surface-chemical-abrasive interactions were determined. From applications point of view, this study serves as a guide for further investigations in pursuing highly effective slurry formulations for copper/low-k interconnect applications.
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Date Issued
2004
Identifier
CFE0000120, ucf:46195
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000120
SURFACE CHEMISTRY OF APPLICATION SPECIFIC PADS AND COPPER CHEMICAL MECHANICAL PLANARIZATION.
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
EFFECTS OF ORTHOPHOSPHATE CORROSION INHIBITOR IN BLENDED WATER QUALITY ENVIRONMENTS
Title
EFFECTS OF ORTHOPHOSPHATE CORROSION INHIBITOR IN BLENDED WATER QUALITY ENVIRONMENTS.
Creator
Stone, Erica, Duranceau, Steven, University of Central Florida
Abstract / Description
This study evaluated the effects of orthophosphate (OP) inhibitor addition on iron, copper, and lead corrosion on coupons exposed to different blends of groundwater, surface water, and desalinated seawater. The effectiveness of OP inhibitor addition on iron, copper, and lead release was analyzed by statistical comparison between OP treated and untreated pilot distribution systems (PDS). Four different doses of OP inhibitor, ranging from zero (control) to 2 mg/L as P, were investigated and non...
Show moreThis study evaluated the effects of orthophosphate (OP) inhibitor addition on iron, copper, and lead corrosion on coupons exposed to different blends of groundwater, surface water, and desalinated seawater. The effectiveness of OP inhibitor addition on iron, copper, and lead release was analyzed by statistical comparison between OP treated and untreated pilot distribution systems (PDS). Four different doses of OP inhibitor, ranging from zero (control) to 2 mg/L as P, were investigated and non-linear empirical models were developed to predict iron, copper, and lead release from the water quality and OP doses. Surface characterization evaluations were conducted using X-ray Photoelectron Spectroscopy (XPS) analyses for each iron, galvanized steel, copper, and lead/tin coupon tested. Also, a theoretical thermodynamic model was developed and used to validate the controlling solid phases determined by XPS. A comparison of the effects of phosphate-based corrosion inhibitor addition on iron, copper, and lead release from the PDSs exposed to the different blends was also conducted. Three phosphate-based corrosion inhibitors were employed; blended orthophosphate (BOP), orthophosphate (OP), and zinc orthophosphate (ZOP). Non-linear empirical models were developed to predict iron, copper, and lead release from each PDS treated with different doses of inhibitor ranging from zero (control) to 2 mg/L as P. The predictive models were developed using water quality parameters as well as the inhibitor dose. Using these empirical models, simulation of the water quality of different blends with varying alkalinity and pH were used to compare the inhibitors performance for remaining in compliance for iron, copper and lead release. OP inhibitor addition was found to offer limited improvement of iron release for the OP dosages evaluated for the water blends evaluated compared to pH adjustment alone. Empirical models showed increased total phosphorus, pH, and alkalinity reduced iron release while increased silica, chloride, sulfate, and temperature contributed to iron release. Thermodynamic modeling suggested that FePO4 is the controlling solid that forms on iron and galvanized steel surfaces, regardless of blend, when OP inhibitor is added for corrosion control. While FePO4 does not offer much control of the iron release from the cast iron surfaces, it does offer protection of the galvanized steel surfaces reducing zinc release. OP inhibitor addition was found to reduce copper release for the OP dosages evaluated for the water blends evaluated compared to pH adjustment alone. Empirical models showed increases in total phosphorus, silica, and pH reduced copper release while increased alkalinity and chloride contributed to copper release. Thermodynamic modeling suggested that Cu3(PO4)2•2H2O is the controlling solid that forms on copper surfaces, regardless of blend, when OP inhibitor is added for corrosion control. OP inhibitor addition was found to reduce lead release for the OP dosages evaluated for the water blends evaluated compared to pH adjustment alone. Empirical models showed increased total phosphorus and pH reduced lead release while increased alkalinity, chloride, and temperature contributed to lead release. Thermodynamic modeling suggested that hydroxypyromorphite is the controlling solid that forms on lead surfaces, regardless of blend, when OP inhibitor is added for corrosion control. The comparison of phosphate-based inhibitors found increasing pH to reduce iron, copper, and lead metal release, while increasing alkalinity was shown to reduce iron release but increase copper and lead release. The ZOP inhibitor was not predicted by the empirical models to perform as well as BOP and OP at the low dose of 0.5 mg/L as P for iron control, and the OP inhibitor was not predicted to perform as well as BOP and ZOP at the low dose of 0.5 mg/L as P for lead control. The three inhibitors evaluated performed similarly for copper control. Therefore, BOP inhibitor showed the lowest metal release at the low dose of 0.5 mg/L as P for control of iron, copper, and lead corrosion.
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Date Issued
2008
Identifier
CFE0002382, ucf:47760
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002382
Long-term Carbon and Copper Impact on Nutrient Removal via Green Sorption Media in Dynamic Linear Ditch Environments
Title
Long-term Carbon and Copper Impact on Nutrient Removal via Green Sorption Media in Dynamic Linear Ditch Environments.
Creator
Ordonez, Diana, Chang, Ni-bin, Randall, Andrew, Sadmani, A H M Anwar, University of Central Florida
Abstract / Description
Nutrient-laden stormwater runoff causes environmental and ecological impacts on receiving water bodies. Biosorption Activated Media (BAM) composed of the sand, tire crumb, and clay have been implemented in stormwater best management practices due to its ability to efficiently remove nutrients from stormwater runoff, such as in roadside linear ditches, via unique chemophysical and microbiological processes. In this study, a set of fixed-bed columns were set up to simulate some external forces...
Show moreNutrient-laden stormwater runoff causes environmental and ecological impacts on receiving water bodies. Biosorption Activated Media (BAM) composed of the sand, tire crumb, and clay have been implemented in stormwater best management practices due to its ability to efficiently remove nutrients from stormwater runoff, such as in roadside linear ditches, via unique chemophysical and microbiological processes. In this study, a set of fixed-bed columns were set up to simulate some external forces in roadside linear ditches and examine how these external forces affect the performance of BAM. In our experiment, scenario 1 simulates the impact that animals such as tortoises, moles and ants produce conduits on the top layer of BAM. Scenario 2 simulates the presence of animals on BAM, together with external compaction. Finally, scenario 3 simulates external compaction such as traffic compaction alone. Furthermore, two baseline conditions were included to sustain the impact assessment of these three scenarios, respectively. They are the long-term presence of carbon in stormwater as carbon can be transported by stormwater runoff from neighboring crop fields, and the long-term presence of copper ions in stormwater as copper depositions can also be found because of electrical wiring, roofing, stormwater ponds disinfection and automobile brake pads in transportation networks. This systematic assessment encompasses some intertwined field complexity in real world systems driven by different hydraulic conditions, microbial ecology, Dissolved Organic Nitrogen (DON) reshape/removal, and long-term addition of carbon and copper (alone) on the effectiveness of total nitrogen removal. The removal efficiencies are substantially linked to varying microbial processes including mineralization, ammonification, nitrification, denitrification, and even dissimilatory nitrate reduction to ammonium, each of which is controlled by different dominant microbial species. The identification of DON compounds at the molecular level was done via a Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-IR-MS) whereas the quantitation of microbial species was done by using quantitative Polymerase Chain Reaction (qPCR). The results from the interactions between microbial ecology and DON decomposition were compared to the external forces and baseline conditions to obtain a holistic understanding of the removals efficiencies of total nitrogen. With the aid of qPCR and FT-IR-MS, this study concluded that the long-term presence of carbon is beneficial for nutrient removal whereas the long-term copper addition inhibits nutrient removal.
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Date Issued
2019
Identifier
CFE0007847, ucf:52816
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007847
Chemophysical Characteristics and Application of Biosorption Activated Media (BAM) for Copper and Nutrient Removal in Stormwater Management
Title
Chemophysical Characteristics and Application of Biosorption Activated Media (BAM) for Copper and Nutrient Removal in Stormwater Management.
Creator
Jones, Jamie, Chang, Ni-bin, Bohlen, Patrick, Wanielista, Martin, University of Central Florida
Abstract / Description
For high groundwater table areas, stormwater wet detention ponds are utilized as the preferred stormwater management throughout the state of Florida. Previous research has found that accumulations of nutrients, algae, heavy metals, pesticides, chlorophyll a, fecal coliform bacteria and low concentrations of dissolved oxygen (DO) are common characteristics of stormwater wet detention ponds. Although these pollutant levels are not regulated within the ponds, states are required to compute the...
Show moreFor high groundwater table areas, stormwater wet detention ponds are utilized as the preferred stormwater management throughout the state of Florida. Previous research has found that accumulations of nutrients, algae, heavy metals, pesticides, chlorophyll a, fecal coliform bacteria and low concentrations of dissolved oxygen (DO) are common characteristics of stormwater wet detention ponds. Although these pollutant levels are not regulated within the ponds, states are required to compute the pollutant load reductions through total maximum daily load (TMDL) programs to meet the water quality requirements addressed by the Clean Water Act (CWA). In this study, field sampling data of stormwater ponds throughout Florida are presented to identify concentration levels of the main contaminants of concern in the discharge of wet detention ponds. Sampling was done to identify possible sources, in addition to possible removal mechanisms via the use of specific sorption media. Nutrients were found as a main problematic pollutant, of which orthophosphate, total phosphorus, ammonia, nitrate, and total nitrogen were targeted whereas heavy metals exhibited minor concerns. Accumulation of high nutrient concentrations may be mitigated by the adoption of best management practices (BMPs) utilizing biosorption activated media (BAM) to remove phosphorus and nitrogen species through physical, chemical, and biological processes. This study aims to increase overall scientific understanding of phosphorus removal dynamics in sorption media systems via Langmuir and Freundlich isotherms and column studies. The removal of phosphorus (P) was proven effective primarily through chemophysical processes. The maximum orthophosphate adsorption capacities were determined under varying conditions of the media within the columns, which were found up to 0.000534 mg-P adsorbed per gram BAM with influent concentrations of 1 mg?L-1 orthophosphate in distilled water and 1 hour hydraulic residence time (HRT). When using spiked pond water under the same conditions, the adsorption capacity was increased about 30 times to 0.01507 mg-P?g-1 BAM presumably due to the properties and concentrations of ions affecting the diffusion rate regulating the surface orthophosphate reactions. These equilibrium media uptake values (q) were used to calculate the life expectancies of the media under varying HRT and influent concentrations of treatment. Chemophysical and biological removal capabilities of the media for total nitrogen, ammonia, and nitrate were effective in columns using 1100 g of BAM. In flow-through column conditions, ammonia had a consistent ~95% removal while effluent nitrate concentrations were highly variable due to the simultaneous nitrification-denitrification processes once an aerobic-anaerobic environment was established. Batch column experiments simulating no-flow conditions within a media bed reactor resulted in orthophosphate removals comparable with the continuous flow conditions, increased total phosphorus effluents indicative of chemical precipitation of orthophosphate, decreased ammonia removal, and increased nitrate removal. Due to a biofilm's sensitivity to even low copper concentrations and accumulation in ponds, a copper sorption media mix of (")green(") materials was generated. Freundlich and Langmuir isotherm tests concluded a successful mix resulting in copper removal efficiencies up to 96%.
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Date Issued
2013
Identifier
CFE0005009, ucf:49995
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005009
Synthesis and Study of Chemo-Hydrothermally Derived Water-Soluble Chitosan and Chiosan-Metal Oxide Composites
Title
Synthesis and Study of Chemo-Hydrothermally Derived Water-Soluble Chitosan and Chiosan-Metal Oxide Composites.
Creator
Basumallick, Srijita, Santra, Swadeshmukul, Kolpashchikov, Dmitry, Zou, Shengli, Ye, Jingdong, Seal, Sudipta, University of Central Florida
Abstract / Description
Chitosan (CS) is a man-made sugar based biopolymer derived from chitin, the second most abundant natural polymer after cellulose. Chitin is sourced from crustacean species such as shrimps and crabs. The chemical structure of chitin contains N-Acetyl D-glucosamine monomer units which forms CS upon deacetylation. In CS, ?-(1-4) linked D-glucosamine units are randomly distributed. Approximately 75% - 80% sugar units contains primary amine groups in commercially available low molecular weight CS....
Show moreChitosan (CS) is a man-made sugar based biopolymer derived from chitin, the second most abundant natural polymer after cellulose. Chitin is sourced from crustacean species such as shrimps and crabs. The chemical structure of chitin contains N-Acetyl D-glucosamine monomer units which forms CS upon deacetylation. In CS, ?-(1-4) linked D-glucosamine units are randomly distributed. Approximately 75% - 80% sugar units contains primary amine groups in commercially available low molecular weight CS. Biodegradability, low toxicity, mucoadhesive and transfecting properties of CS polymer are attractive for applications as oral and nasal drug delivery systems. Chitosan polymer is water insoluble at neutral pH. To solubilize CS, dilute mineral acid (such as hydrochloric acid and nitric acid) or organic acid (such as acetic acid) is often used. CS contains both hydroxyl and primary amine groups in its structure. In acidic solution, the amine functional groups become protonated (positively charged). Positively charged CS remains stable only in low pH condition due to electrostatic repulsion of charged polymer segments. Therefore, by using a suitable anionic (negatively charged) cross-linker, stable CS particles (such as nanoparticles and microspheres) can be prepared. This is popularly known as ionic gelation method. Extensive studies have been done on the synthesis of drug loaded CS particles where particle integrity is maintained by ionic gelation using tripolyphosphate (TPP, an anionic cross-linker). Drug encapsulated CS-TPP composite particles are shown to maintain biodegradability and biocompatibility. The CS-TPP composite particles exhibits very limited dispersibility at neutral pH conditions specifically in neutral buffered conditions. A number of biomedical applications (including systemic drug formulations) however demands buffer-stable CS composite particles for achieving optimal therapeutic outcome.To overcome the above dispersibility issues, CS polymer and CS particles units have been chemically modified using water soluble motifs (such as water soluble polymer or ligands). This approach is very cumbersome and usually involves multiple purification steps. Chemical modification of natural CS chain introduces risks of compromising biodegradability and biocompatibility. Therefore, there is a strong need for developing a straightforward method of making water soluble CS and CS particles.Chapter 1 of this dissertation presents an overview of the CS polymer, various applications of CS polymers, methods of making CS polymers and CS particles, current limitations of synthesis methods for preparing stable chitosan particles at neutral pH conditions and finally delineates the scope of the proposed research work.Chapter 2 describes development of chemo-hydrothermal synthesis method for producing water soluble CS polymer and water dispersible CS composite particles. In this method, a chemical (depolymerizing agent) is used to treat CS polymer in a hydrothermal (high temperature and high pressure) condition. Two types of depolymerizing agents have been used, an inorganic acid (e.g. hydrochloric acid, HCl) and a bicarboxylic organic acid (e.g. tartaric acid, TA). In both cases, 100% depolymerized CS polymer was obtained. Chemical characteristics of the depolymerized CS were comparable to acid solubilized CS. CS polymer exhibits weak fluorescence. Interestingly, hydrothermally depolymerized CS shows strong fluorescence properties irrespective of the nature of depolymerizing agent used. TA not only depolymerized CS but also formed CS-TA composite particulate structures in solution via self-assembly. The CS-TA composite particles are stable in a wide pH range from 5 to 11. Detailed spectroscopic and microscopic studies have been done to understand the basic mechanism of particle formation and increase in fluorescence properties (i.e. structure-property relationship). Usefulness of CS-TA in solubilizing water-insoluble cargos (such as fluorescein isothiocyanate, FITC) has been demonstrated.Chapter 3 is focused on hydrothermal synthesis of mixed-valence copper (Cu) oxide loaded CS-TA composite particles and their characterization. Crystalline Cu oxide nanoparticles were coated with the CS-TA layer. Water dispersibility of Cu oxide greatly improved upon coating with CS-TA material. To demonstrate catalytic activity of Cu-oxide loaded CS-TA film in sequestering carbon dioxide (CO2), an electrochemical setup was used. Electrochemical reduction of CO2 was successfully demonstrated. It was observed that CS-TA environment not only maintained catalytic properties of Cu oxide but also allowed solution processing of Cu-oxide film onto the electrode surface.Chapter 4 discusses a convenient method of making monodispersed water dispersible Cu loaded chitosan nanoparticles (Cu-CS) using HCl depolymerized CS polymer. The purpose of this study was to investigate if there was any improvement in antibacterial properties of Cu-CS nanoparticles prepared using hydrothermally treated CS polymer. Interestingly, it was observed that the antibacterial efficacy of Cu was not compromised in Cu-CS nanoparticles. Moreover, the materials exhibited improvement in antibacterial efficacy against both Gram-negative and Gram-positive bacteria species. A plausible mechanism has been proposed to explain antibacterial results.Chapter 5 summarizes major findings of this dissertation research and presents future research directions.
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Date Issued
2014
Identifier
CFE0005461, ucf:50395
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005461
Functional Characterization of Green Sorption Media and Scaling of Pilot Studies for Copper Removal in Stormwater Runoff
Title
Functional Characterization of Green Sorption Media and Scaling of Pilot Studies for Copper Removal in Stormwater Runoff.
Creator
Houmann, Cameron, Chang, Ni-bin, Wanielista, Martin, Lee, Woo Hyoung, University of Central Florida
Abstract / Description
Green adsorption media with the inclusion of renewable and recycled materials can be applied as a stormwater best management practice for copper removal. A green adsorption media mixture composed of recycled tire chunk, expanded clay aggregate, and coconut coir was physicochemically evaluated for its potential use in an upflow media filter. The results found that the use of the green adsorption media mixture in isolation or the coconut coir with an expanded clay filtration chamber could be an...
Show moreGreen adsorption media with the inclusion of renewable and recycled materials can be applied as a stormwater best management practice for copper removal. A green adsorption media mixture composed of recycled tire chunk, expanded clay aggregate, and coconut coir was physicochemically evaluated for its potential use in an upflow media filter. The results found that the use of the green adsorption media mixture in isolation or the coconut coir with an expanded clay filtration chamber could be an effective and reliable stormwater best management practice for copper removal. A suite of tests were conducted on the media mixture and the individual media components including studies of isotherm, reaction kinetics, column adsorption and reaction kinetics. Batch adsorption tests revealed that the media and media mixture follow both the Freundlich and Langmuir isotherm models and that the coconut coir had the highest affinity for copper. A screening of desorbing agents revealed that hydrochloric acid has good potential for copper desorption, while batch tests for desorption with hydrochloric acid as the desorbing agent showed the data fit the Freundlich isotherm model. Reaction kinetics revealed that the adsorption reaction took less than 1 hour to reach equilibrium and that it followed pseudo-second order kinetics for the mixture and coconut. Desorption kinetic data had high correlation with the pseudo-second order model and revealed a rapid desorption reaction. Batch equilibrium data over 3 adsorption/desorption cycles found that the coconut coir and media mixture were the most resilient and demonstrated that they could be used through 3 or more adsorption/desorption cycles. The coconut coir also performed the best under dynamic conditions, having an equilibrium uptake of 1.63 mg?g-1, compared to 0.021 mg?g-1 at an influent concentration of 1.0 mg?L-1 and a hydraulic retention time of 30 minutes. A physical evaluation of the media found the macro-scale properties, such as particle size distribution and mass-volume relationships, and observed the micro-scale properties such as surface and pore microstructures, crystalline structures, and elemental composition. FE-SEM imaging found a strong correlation between the porosity of the micro pore structure and the adsorptive capacity. The equilibrium and dynamic adsorption testing results were confirmed by elemental analysis, which showed measureable quantities of copper in the coconut coir and media mixture after adsorption followed by partial desorption. A new scaling-up theory was developed through a joint consideration of the Damk(&)#246;hler and P(&)#233;clet numbers for a constant media particle size such that a balance between transport-controlled and reaction-controlled kinetics can be harmonized. A series of column breakthrough tests at varying hydraulic residence times revealed a clear peak adsorptive capacity for the media mixture at a Damk(&)#246;hler number of 2.7. The P(&)#233;clet numbers for the column breakthrough tests indicated that mechanical dispersion is an important effect that requires further consideration in the scaling-up process. However, perfect similitude of the Damk(&)#246;hler number cannot be maintained for a constant media particle size, and relaxation of hydrodynamic similitude through variation of the P(&)#233;clet number must occur.
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Date Issued
2015
Identifier
CFE0005630, ucf:50205
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005630
Precision Metrology of Laser Plasmas in the XUV Band
Title
Precision Metrology of Laser Plasmas in the XUV Band.
Creator
Szilagyi, John, Richardson, Martin, Sundaram, Kalpathy, Abdolvand, Reza, Baudelet, Matthieu, Shivamoggi, Bhimsen, University of Central Florida
Abstract / Description
The XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 (-) 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor...
Show moreThe XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 (-) 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor manufacturing industry, medical surgery, micromachining, microscopy, and spectroscopy have begun to benefit from the short wavelengths and the high photon energies of this light. At present, the semiconductor chip industry is the primary reason for the investment in, and development of, XUV sources, optics, and detectors. The demand for high power EUV light sources at 13.5 nm wavelength is driven by the development of the next generation of semiconductor lithography tools. The development of these tools enables the continued reduction in size, and the increase in transistor density of semiconductor devices on a single chip. Further development and investigation of laser produced plasma EUV light sources is necessary to increase the average optical power and reliability. This will lead to an increase in the speed of EUV lithographic processes, which are necessary for future generations of advanced chip design, and high volume semiconductor manufacturing. Micromachining, lithography, and microscopy benefit from improvements in resolution due to the shorter wavelengths of light in the VUV band. In order to provide adequate illumination for these applications, sources are required which are brighter and have higher average power. Laser produced plasma (LPP) VUV light sources are used extensively for lithography and defect detection in semiconductor manufacturing. Reductions in the wavelength and increases in the average power will increase the rate and yield of chip manufacture, as well as reduce the costs of semiconductor manufacture.The work presented in this thesis, describes the development of two laser plasma source facilities in the Laser Plasma Laboratory at UCF, which were designed to investigate EUV and VUV laser plasma sources. The HP-EUV-Facility was developed to optimize and demonstrate a high power 13.5 nm EUV LPP source. This facility provides high resolution spectroscopy across 10.5 - 20 nm, and absolute energy measurement of 13.5 nm +/- 2% in 2? sr. The VUV-MS-Facility was developed to investigate VUV emission characteristics of laser plasmas of various target geometries and chemistries. This facility provides absolute calibrated emission spectra for the 124 - 250 nm wavelength range, in addition to, at wavelength plasma imaging. Calibrated emission spectra, in-band power, and conversion efficiency are presented in this work for gas targets of Argon, Krypton, and Xenon and solid targets of Silicon, Copper, Molybdenum, Indium, Tantalum, Tin, and Zinc, across the laser intensity range of 8.0x10^6 (-) 3.2x10^12 W/cm2.
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Date Issued
2017
Identifier
CFE0006805, ucf:51793
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006805

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