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Title: Development of Molecularly Imprinted Polymers for Forensic Applications.
Creator: Martinez, Sara, Sigman, Michael, Bridge, Candice, Yestrebsky, Cherie, University of Central Florida
Abstract / Description: In some forensic disciplines various methods of extraction are used to perform analysis. Among these methods, solid phase extraction (SPE) and solid phase microextraction (SPME) are used in fields such as toxicology and explosives analysis. To enhance extraction efficiency in SPE and SPME, molecularly imprinted polymers (MIPs), which are designer polymers, can be more selective for the binding of an analyte or group of analytes that are similarly structured. Separation of analytes from...
Show moreIn some forensic disciplines various methods of extraction are used to perform analysis. Among these methods, solid phase extraction (SPE) and solid phase microextraction (SPME) are used in fields such as toxicology and explosives analysis. To enhance extraction efficiency in SPE and SPME, molecularly imprinted polymers (MIPs), which are designer polymers, can be more selective for the binding of an analyte or group of analytes that are similarly structured. Separation of analytes from complex mixtures is possible by utilizing these polymers. This may be especially useful in forensic applications where sample sizes may be small and composition may be complex. In this work, MIP solid phase microextraction fibers (MIP-SPME) were fabricated and caffeine was selectively sampled in the presence of theophylline and theobromine. Calibration studies were performed using the MIP-SPME to quantitate the concentration of caffeine in teas and coffees. MIP-SPME fibers were also prepared with 2,4-dinitrotoluene and deuterated 2,6-dinitrotoluene. Less selectivity was obtained for extraction of 2,4-DNT and 2,6-DNT in the presence of other DNT isomers. Fabricated blank polymers extracted analytes at the same response as templated polymers for both caffeine and DNT, despite expected results. MIP-SPE columns were also fabricated using deuterated 2,6-DNT to determine if changing the extraction procedure would increase extraction selectivity. Using different solvents in the extraction procedure changed the extraction performance efficiency of the MIPs due to the change in solvent polarity. All samples were analyzed using gas chromatography mass spectrometry.
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Date Issued: 2016
Identifier: CFE0006477, ucf:51423
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006477

Title: Classification of Silicone-Based Personal and Condom Lubricants Using DART-TOFMS.
Creator: Harvey, Lauren, Bridge, Candice, Sigman, Michael, Campiglia, Andres, Yestrebsky, Cherie, University of Central Florida
Abstract / Description: Sexual lubricants are used to enable sexual encounters. There are different types of sexual lubricants such as water-based, oil-based, and silicone-based. They come pre-applied to condoms and separately in bottles as personal lubricants. Although sexual lubricants are intended for consensual use, they are also unfortunately used during the commission of sexual assaults. The analysis of sexual lubricants facilitates sexual assault investigations. With the increased usage of condoms in sexual...
Show moreSexual lubricants are used to enable sexual encounters. There are different types of sexual lubricants such as water-based, oil-based, and silicone-based. They come pre-applied to condoms and separately in bottles as personal lubricants. Although sexual lubricants are intended for consensual use, they are also unfortunately used during the commission of sexual assaults. The analysis of sexual lubricants facilitates sexual assault investigations. With the increased usage of condoms in sexual assault cases, the potential of collected DNA evidence in each case is reduced. In the absence of biological evidence, the presence of sexual lubricants after a sexual assault can provide an additional link between a suspect and the crime scene and/or victim. Having the ability to compare known and unknown sexual lubricants may be the only actionable information available for investigators. Current lubricant analysis only classifies samples into lubricant types based on the major component such as glycerol, petrolatum, and polydimethylsiloxane for water-based, oil-based, and silicone-based lubricants respectively. Differentiation within major types has not been explored. Previously, protocols have been developed to detect and categorize personal lubricants using Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), liquid chromatography mass spectrometry (LC-MS), and pyrolysis GC-MS. FTIR is routinely used as a screening tool to detect peaks of the major lubricant components and the mass spectrometry (MS) techniques are commonly used to confirm the presence of some of the major components, excluding PDMS.This thesis focused on the differentiation of silicone-based personal and condom lubricants because it is a common type of lubricant due to its ability to reduce friction for a longer period of time. Fifty-six (56) silicone personal and condom lubricants were analyzed to identify unique characteristics that can be used to determine individual sub-classes and test those sub-classes. Direct analysis in real time-time of flight mass spectrometry (DART-TOFMS) was utilized because minor and unique molecular ions that could be attributed to different sub-groups can easily be distinguished from the major sample peaks. This is primarily based on the direct mass spectrometry design of the instrumentation that can differentiate minor components from major components that might not be observed using traditional chromatographic separation. The DART source creates molecular ions for individual components in mixed samples under atmospheric conditions in either positive or negative mode. The TOF-MS, which is capable of high resolution and accurate mass analysis, allows more accurate and precise detection of molecular component ions. Additionally, no sample preparation is required to analyze neat samples, which minimizes potential contamination issues. Attenuated total reflectance-FTIR (ATR-FIR) was used to analyze the training set personal lubricants to compare previous methods of analysis to the newly developed DART-TOFMS method of analysis.Principle component analysis (PCA) and cluster analysis were used to identify potential sub-groups and subsequently a classification scheme. Linear discriminant analysis was utilized to conduct leave one out cross validation and to categorize test samples. Eight sub-groups were developed based on the presence and/or absence of PDMS and minor component peaks observed.A classification scheme was developed using the eight sub-groups identified through PCA and cluster analysis. This classification scheme was tested using LDA to classify blind samples. One group includes a scented personal lubricant. Another group includes flavored condom lubricants. The other groups were developed based on the relative intensity of PDMS peaks and minor component peaks. Variation of the intensity of PDMS peaks between and within samples of different lot numbers causes some misclassification of samples. This classification scheme also doesn't take into account real-world factors such as dilution and biodegradation. Although further research is required to create a more stable classification scheme, the identified sub-groups are a good foundation for the creation of a lubricant database and finalized classification scheme.
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Date Issued: 2016
Identifier: CFE0006459, ucf:51415
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006459

Title: Optimizing Laboratory Pyrolysis Methods to Compliment Real World Fire Debris.
Creator: Coulson, Richard, Sigman, Michael, Bridge, Candice, Yestrebsky, Cherie, Campiglia, Andres, University of Central Florida
Abstract / Description: Forensic analysts are tasked with determining the presence of ignitable liquid residue in fire debris. Analysis of fire debris allows the analyst to understand how the fire occurred. However, the presence of some substrates can potentially impact the identification of ignitable liquid residue and classification of a sample as positive or negative for the presence of ignitable liquid. Pyrolysis of building materials and furnishings (substrates) lead to background interference within the...
Show moreForensic analysts are tasked with determining the presence of ignitable liquid residue in fire debris. Analysis of fire debris allows the analyst to understand how the fire occurred. However, the presence of some substrates can potentially impact the identification of ignitable liquid residue and classification of a sample as positive or negative for the presence of ignitable liquid. Pyrolysis of building materials and furnishings (substrates) lead to background interference within the resulting chromatographic profile. To combat misclassification of a sample as positive for ignitable liquid residue, knowledge of the pyrolysis products from individual substrates is of utmost importance. However, unburned reference samples from a fire scene can be difficult to obtain. The use of a database in conjunction with the analysis of the samples can lead to a more complete analysis of fire debris. Within this research, four different burn methods (modified destruction distillation method, top heat, bottom heat, and tube furnace) were utilized in burning eight different flooring substrates (polyester, nylon, and olefin carpeting, carpet padding, vinyl flooring, laminate flooring, yellow pine, and plywood) to obtain pyrolysis/combustion product profiles. Each burn method was performed at three different burn times for a total of twelve different burns of each substrate. Standard methods, ASTM E1412-12 and ASTM E1618-14, were used in the extraction and interpretation of the laboratory burn products. Principal component analysis (PCA) was used to relate the laboratory burn results to neat ignitable liquid/substrate and large scale burn data sets.Laboratory burn data projected into the PCA space displayed that the laboratory burn data is similar to the data contained within the ILRC and Substrate databases. Differences observed within laboratory burn data projections illustrated the variability of the laboratory burn methods. The composition of the substrate dictated the pyrolysis/combustion products produced. While this research only focuses on flooring substrates, an increase in the number of different types of materials in the Substrate Database can aid analysts in identifying common pyrolysis/combustion products observed in fire debris.
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Date Issued: 2017
Identifier: CFE0006578, ucf:51357
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006578

Title: Evaluation of The Biodegradability and Toxicity of PCA and mPCA.
Creator: Rueda, Juan, Randall, Andrew, Duranceau, Steven, Yestrebsky, Cherie, University of Central Florida
Abstract / Description: The main types of hypergolic propellants used at Kennedy Space Center (KSC) are hydrazine (HZ) and monomethylhydrazine (MMH). HZ and MMH are classified as hazardous materials and they are also known to be potentially carcinogenic to humans; therefore, handling these substances and their waste is strictly regulated. The wastes streams from HZ and MMH have been estimated to be the main hazardous wastes streams at KSC. Currently at KSC these wastes are first neutralized using citric acid and...
Show moreThe main types of hypergolic propellants used at Kennedy Space Center (KSC) are hydrazine (HZ) and monomethylhydrazine (MMH). HZ and MMH are classified as hazardous materials and they are also known to be potentially carcinogenic to humans; therefore, handling these substances and their waste is strictly regulated. The wastes streams from HZ and MMH have been estimated to be the main hazardous wastes streams at KSC. Currently at KSC these wastes are first neutralized using citric acid and then they are transported on public roads for incineration as hazardous materials. A new method using alpha ketoglutaric acid (AKGA) was proposed to treat HZ and MMH wastes. From the reaction of AKGA with HZ and MMH two stable products are formed, 1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid (PCA) and l-methyl-1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid (mPCA), respectively.The cost of purchasing AKGA is greater than the cost of purchasing citric acid; thus, AKGA can only become a cost effective alternative for the treatment of HZ and MMH wastes if the products of the reactions (PCA and mPCA) can be safely disposed of into the sewage system without affecting the treatment efficiency and effluent quality of the wastewater treatment plant (WWTP). In this research mPCA and PCA were analyzed for acute toxicity using fish and crustaceans as well as their effect on the wastewater treatment efficiency and viability using AS microbes, and their biodegradability by AS organisms. Acute toxicity on fish and crustaceans was investigated according to the methods for acute toxicity by USEPA (USEPA Method EPA-821-R-02-012) using Ceriodaphnia dubia (96 hours) and Pimephales promelas (96 hours) as the test organisms. The effect of mPCA and PCA in the treatment efficiency and viability were estimated from respiration inhibition tests (USEPA Method OCSPP 850.3300) and heterotrophic plate counts (HPCs). Lastly, the biodegradability of mPCA and PCA was assessed using the Closed Bottle Test (USEPA Method OPPTS 835.3110). For mPCA, the 96 hours LC50 for C. dubia was estimated at 0.77 (&)#177; 0.06 g/L (with a 95% confidence level) and the NOEC was estimated at 0.5 g/L. For P. promelas, the LC50 was above 1.5 g/L but it was noticed that mPCA had an effect on their behavior. Abnormal behavior observed included loss of equilibrium and curved spine. The NOEC on the fish was estimated at 0.75 g/L. PCA did not exhibit a significant mortality on fish or crustaceans. The LC50 of PCA in P. promelas and C. dubia was (>) 1.5 g/L and the NOEC was 1.5 g/L for both organisms. An Inhibitory effect on the heterotrophic respiration of activated sludge organisms was not observed after exposing them for 180-min to PCA and mPCA at concentrations of up to 1.5 g/L compared to the blank controls. Overall the impact of PCA and mPCA on total respiration rates was small, and only observed at 1,500 mg/L if at all. The difference was apparently caused by inhibition of nitrification rather than heterotrophic inhibition. However due to the variability observed in the measurements of the replicates, it is not possible to firmly conclude that PCA or mPCA at 1,500 mg/L was inhibitory to nitrification.Based on the results from the HPCs, mPCA and PCA did not affect the viability of heterotrophic organisms at 750 mg/L. In the BOD-like closed bottle test using a diluted activated sludge mixed liquor sample, the AS microorganisms were capable of biodegrading up to 67% of a 2 mg/L concentration of PCA (with respect to its theoretical oxygen demand, or ThOD) in 28 days. No biodegradation was observed in the samples containing 2 and 5 mg/L of mPCA after 28 days of incubation using a diluted activated sludge mixed liquor sample as inoculum.The results of this study show that mPCA is more toxic than PCA to Ceriodaphnia dubia and Pimephales promelas. However neither mPCA nor PCA had an effect on the heterotrophic respiration of an AS mixed liquor sample at 1.5 g/L and there was probably no significant inhibition of the nitrification respiration. Samples of PCA and mPCA at 2 and 5 mg/L could not be completely degraded (with respect to their total theoretical oxygen demand) by dilute AS biomass during a 28 day incubation period. mPCA did not show significant degradation in the two different biodegradation tests performed.
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Date Issued: 2013
Identifier: CFE0004744, ucf:49779
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004744

Title: Study of the Effect of Surface Morphology on Mass Transfer and Fouling Behavior of Reverse Osmosis and Nanofiltration Membrane Processes.
Creator: Fang, Yuming, Duranceau, Steven, Randall, Andrew, Wang, Dingbao, Yestrebsky, Cherie, University of Central Florida
Abstract / Description: Reverse osmosis (RO) and nanofiltration (NF) membranes are pressure driven, diffusion controlled process. The influence of surface characteristics on membrane process performance is considered significant and is not well understood. Current mass transport models generally assume constant mass transfer coefficients (MTCs) based on a homogeneous surface. This work evaluated mass transfer processes by incorporating surface morphology into a diffusion-based model assuming MTCs are dependent on...
Show moreReverse osmosis (RO) and nanofiltration (NF) membranes are pressure driven, diffusion controlled process. The influence of surface characteristics on membrane process performance is considered significant and is not well understood. Current mass transport models generally assume constant mass transfer coefficients (MTCs) based on a homogeneous surface. This work evaluated mass transfer processes by incorporating surface morphology into a diffusion-based model assuming MTCs are dependent on the thickness variation of the membrane's active layer. To mathematically create such a surface layer, Gaussian random vectors embedded in a software system (MATLAB) were used to generate a three-dimensional ridge and valley active layer morphologies. A (")SMOOTH(") script was incorporated to reduce the influence of outlying data and make the hypothetical surfaces visually comparable to the AFM images. A non-homogeneous solution diffusion model (NHDM) was then developed to account for surface variations in the active layer. Concentration polarization (CP) is also affected by this non-homogeneous surface property; therefore, the NHDM was modified by incorporating the CP factor. In addition, recent studies have shown that the membrane surface morphology influences colloidal fouling behavior of RO and NF membranes. With consideration of the spatial variation of the cake thickness along the membranes, a fouling model was established by assuming cake growth is proportional to the localized permeate flow. Flux decline was assumed to be controlled by the resistance of cake growth and accumulated particle back diffusion at the membrane surface.A series of simulations were performed using operating parameters and water qualities data collected from a full-scale brackish water reverse osmosis membrane water treatment plant. The membrane channel was divided into a thousand uniform slices and the water qualities were determined locally through a finite difference approach. Prediction of the total dissolved solid (TDS) permeate concentration using the model was found to be accurate within 5% to 15% as an average percentage of difference (APD) using the NHDM developed in this research work. A comparison of the NHDM and the modified NHDM for concentration polarization (CP) with the commonly accepted homogeneous solution diffusion model (HSDM) using pilot-scale brackish water RO operating data indicated that the NHDM is more accurate when the solute concentration in the feed stream is low, while the NHDMCP appears to be more predictive of permeate concentration when considering high solute feed concentration. Simulation results indicated that surface morphology affects the water qualities in the permeate stream. Higher salt passage was expected to occur at the valley areas when diffusion mass transfer would be greater than at the peaks where the thin-film membrane is thicker. A rough surface tends to increase the TDS accumulation on the valley areas, causing an enhanced osmotic pressure at the valleys of membrane.To evaluate the impact of surface morphology on RO and NF performance, fouling experiments were conducted using flat-sheet membrane and three different nanoparticles, which included SiO2, TiO2 and CeO2. In this study, the rate and extent of fouling was markedly influenced by membrane surface morphology. The atomic force microscopy (AFM) analysis revealed that the higher fouling rate of RO membranes compared to that of NF membranes is due to the inherent ridge-and-valley morphology of the RO membranes. This unique morphology increases the surface roughness, leading to particle accumulation in the valleys, causing a higher flux decline than in smoother membranes. Extended fouling experiments were conducted using one of the RO membranes to compare the effect of different particles on actual water. It was determined that membrane flux decline was not affected by particle type when the feed water was laboratory grade water. On the other hand, membrane flux decline was affected by particle type when diluted seawater served as the feed water. It was found that CeO2 addition resulted in the least observable flux decline and fouling rate, followed by SiO2 and TiO2. Fouling simulation was conducted by fitting the monitored flux data into a cake growth rate model. The model was discretized by a finite difference method to incorporate the surface thickness variation. The ratio of cake growth term (k_1) and particle back diffusion term (k_2) was compared in between different RO and NF membranes. Results indicate that k_2 was less significant for surfaces that exhibited a higher roughness. It was concluded that the valley areas of thin-film membrane surfaces have the ability to capture particles, limiting particle back diffusion.
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Date Issued: 2013
Identifier: CFE0004837, ucf:49707
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004837

Title: In situ Treatment Systems for Remediation of Polychlorinated Biphenyl-contaminated building materials.
Creator: Almutairi, Adibah, Yestrebsky, Cherie, Beazley, Melanie, Legron-Rodriguez, Tamra, Bridge, Candice, Randall, Andrew, University of Central Florida
Abstract / Description: Polychlorinated Biphenyls (PCBs) are a family of synthetic organohalides comprising 209 congeners which were used historically as additives in paint and caulking materials over a span of many years. Even though the production of PCBs in the USA has been banned since the late 1970s, their former prevalence and widespread use means many structures are still coated with PCB-laden paints. In addition, the presence of PCBs in elastic sealants has resulted in transport of PCBs into concrete...
Show morePolychlorinated Biphenyls (PCBs) are a family of synthetic organohalides comprising 209 congeners which were used historically as additives in paint and caulking materials over a span of many years. Even though the production of PCBs in the USA has been banned since the late 1970s, their former prevalence and widespread use means many structures are still coated with PCB-laden paints. In addition, the presence of PCBs in elastic sealants has resulted in transport of PCBs into concrete structures and has caused soil contamination around buildings. PCB-contaminated building materials have become a significant concern for the environment and building occupants due to their carcinogenic nature and potential indoor contamination. This results in an urgent need for development of a cost-effective method to extract and degrade PCBs from contaminated materials. Experiments employing reductive dehalogenation through the use of zero-valent magnesium (ZVMg) ball-milled with activated carbon (AC) in an acidified solvent system have shown that PCBs can be broken down even in the presence of water. This research describes the development of two delivery systems for effective deployment of this treatment reaction to field samples. Two treatment systems formulated in this process, the Non-Metal Treatment System (NTMS) and the Activated Metal Treatment System (AMTS), are capable of extracting or extracting and degrading, respectively, trapped PCBs within a variety of building materials. In the development of NMTS and AMTS, an acidified dual system of ethanol/ethyl lactate was used as solvent while ZVMg over activated carbon is used in the AMTS. After development, applications of the systems extended to laboratory prepared PCB-laden paint as well as field samples received from Seattle. A marked successful on PCB remediation was observed. The green solvent 2-butoxyethanol is approved by both the EPA and the FDA, and is an interesting alternative for the dechlorination of PCBs. Novel versions of NMTS and AMTS were developed by substituting 2-butoxyethanol for ethanol/EL and used on a set of paint chips and building materials from the same field site. PCBs were degraded significantly below their starting concentrations with removal efficiency greater than 99% for all samples after two weeks of treatment. The use of acidified 2-butoxyethanol and ZVMg permitted the extraction and destruction of PCBs from contaminated building materials in a one-step treatment. Additional studies were conducted on laboratory-prepared concrete where transport of the organic solvents (used in development of NMTS/AMTS) into the concrete structure was studied. PCB concentrations in concrete after treatment were reduced to below the limit of detection.
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Date Issued: 2018
Identifier: CFE0007388, ucf:52064
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007388

Title: Thermo- and Zero-Valent Iron-Activated Persulfate Oxidation of 3,5,6-Trichloro-2-pyridinol in an Aquatic System.
Creator: Mogharbel, Roaa, Yestrebsky, Cherie, Beazley, Melanie, Zou, Shengli, Legron-Rodriguez, Tamra, Randall, Andrew, University of Central Florida
Abstract / Description: The compound 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of the broad-spectrumorganophosphorous insecticide chlorpyrifos, is both more persistent and more water soluble thanits parent compound. This difference, which allows TCPy to more readily leach into surface waterand groundwater, has led to widespread contamination of TCPy in soils and aquatic environments.In this study, the degradation of TCPy by sulfate radicals was evaluated using zero valent ironactivatedpersulfate systems and...
Show moreThe compound 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of the broad-spectrumorganophosphorous insecticide chlorpyrifos, is both more persistent and more water soluble thanits parent compound. This difference, which allows TCPy to more readily leach into surface waterand groundwater, has led to widespread contamination of TCPy in soils and aquatic environments.In this study, the degradation of TCPy by sulfate radicals was evaluated using zero valent ironactivatedpersulfate systems and heat activated persulfate system in aqueous media. Responsesurface methodology coupled with Box-Behnken design was applied in these studies to evaluatethe effects of the independent variables on the mineralization of TCPy by both systems. In eachsystem, the interactions, coefficients, and residuals of these variables were statically evaluated byAnalysis of variance. Results indicate that both systems can effectively oxidized TCPy in water.While ZV/PS exhibited a high mineralization rate of TCPy up to 81.1%, TCPy was completelymineralized in heat activated PS system. The reaction kinetics of the degradation process wereexamined as functions of experimental parameters in each system and the result revealed that theoxidation of TCPy in both systems followed a pseudo-first-order model under all conditions tested.Radical scavenging tests indicated that sulfate radicals are the predominated species in zero valentiron activated persulfate system, whereas hydroxyl radicals are the predominated species in heatactivated persulfate system. The presence of chloride, sulfate and phosphate anions showednegligible effects on TCPy oxidation by heat activated PS system. The degradation pathways ofTCPy were proposed based on the products identified by GC-MS. Calculated ?G values usingdensity functional theory agreed with the proposed experimental pathway.
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Date Issued: 2018
Identifier: CFE0007762, ucf:52386
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007762

Title: Magnesium-based treatment for the degradation of octachlorodibenzofuran and trinitrotoluene.
Creator: Mogharbel, Amal, Yestrebsky, Cherie, Beazley, Melanie, Zou, Shengli, Legron-Rodriguez, Tamra, Randall, Andrew, University of Central Florida
Abstract / Description: The aim of the present research is to investigate the efficacy of using ball-milled zero-valent magnesium (ZVMg) with and without activated carbon (AC) for the dechlorination of polychlorinated dibenzofurans. Three different solvent systems are presented here which are ethanol, ethanol/ethyl lactate (90:10), and 2-butoxyethanol. These solvents in combination with ZVMg with and without activated carbon were tested towards the degradation of octachlorodibenzofuran (OCDF, the most highly...
Show moreThe aim of the present research is to investigate the efficacy of using ball-milled zero-valent magnesium (ZVMg) with and without activated carbon (AC) for the dechlorination of polychlorinated dibenzofurans. Three different solvent systems are presented here which are ethanol, ethanol/ethyl lactate (90:10), and 2-butoxyethanol. These solvents in combination with ZVMg with and without activated carbon were tested towards the degradation of octachlorodibenzofuran (OCDF, the most highly chlorinated PCDF congener). All the tested systems were very powerful and reductively dechlorinated OCDF to less chlorinated congeners. However, the system of ball-milled ZVMg and ethanol was the only system which converted OCDF and all byproducts to dibenzofuran, the chlorine- free compound. Kinetic results for all the studied systems fit a pseudo-first-order decay model with respect to OCDF degradation. A detailed study of the formed byproducts during the dechlorination process and a proposed degradation pathway for OCDF are present in this research. The systems consisting of ZVMg and ZVMg/AC in acidified ethanol and acidified 2-butoxyethanol were examined towards the degradation of the low-chlorinated congener 2,8-dichlorodibenzofuran. This compound was degraded efficiently in all systems. The addition of activated carbon enhanced the degradation kinetics of 2,8-dichlorodibenzofuran degradation. Another study using ZVMg and ZVMg/AC in acidified ethanol was conducted to evaluate the efficiency of the system towards the remediation of the explosive contaminant trinitrotoluene (TNT). Both systems were effective in the degradation of TNT and the reactions were found to follow pseudo-first-order kinetics. A plausible degradation pathway is proposed in this study based on the identified degradation products.
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Date Issued: 2018
Identifier: CFE0007761, ucf:52374
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007761

Title: Remediation of chlorinated alkanes by zero valent iron with vitamin B12 and Utilization of a modified Gradual Release of Responsibility model in a large enrollment chemistry course.
Creator: Lapeyrouse, Nicole, Yestrebsky, Cherie, Beazley, Melanie, Chen, Gang, Rex, Matthew, Randall, Andrew, University of Central Florida
Abstract / Description: The following dissertation looks at addressing environmental contaminants in the environment and the integration of an active learning style in an introductory chemistry course. It begins with addressing the concern for chlorinated propanes and ethane in the environment and the importance of looking into environmental remediation applications. This research looks at incorporating vitamin B12 as an environmentally friendly catalyst in the presence of zero valent iron for the reduction of...
Show moreThe following dissertation looks at addressing environmental contaminants in the environment and the integration of an active learning style in an introductory chemistry course. It begins with addressing the concern for chlorinated propanes and ethane in the environment and the importance of looking into environmental remediation applications. This research looks at incorporating vitamin B12 as an environmentally friendly catalyst in the presence of zero valent iron for the reduction of chlorinated propanes and ethane. Chapter 2 presents the analytical methods and conditions in which samples were run. The results from these experiments are discussed in length in Chapter 3. Our results confirmed the hypothesis that vitamin B12 could act as an electron mediator to facilitate the reduction of the chlorinated propanes and ethane. Degradation was examined by observing the formation of byproduct peaks and the release of free chloride into solution. In Chapter 4, vitamin B12 is integrated into an already established industrial application technique, emulsified zero valent iron, and we observed the degradation of 1,2,3-trichloropropane with the formation of byproducts as the reaction progressed. In Chapter 5, this section of the dissertation focused on chemical education and observing an active learning technique in a fundamental chemistry course. The following study was designed to increase students' positive attitude, engagement, and responsibility in a large enrollment chemistry course by utilizing a modified Gradual Release of Responsibility (GRR) model. GRR progressively transfers responsibility from the instructor to the student, allowing students to be more independent and helping them to address atypical problems. Students were assessed using iClickers to monitor their understanding and engagement, as well as surveys to determine their attitudes regarding this specific style of teaching. The results from this study demonstrated that implementing the GRR teaching style had a positive effect on student academic performance and shows the importance of using an active teaching model in a large enrollment course.
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Date Issued: 2018
Identifier: CFE0007759, ucf:52373
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007759

Title: Advancements in Liquid Chromatography for the Determination of Polycyclic Aromatic Compounds in Environmental Samples.
Creator: Hayes, Hugh, Campiglia, Andres, Harper, James, Yestrebsky, Cherie, Frazer, Andrew, Coffey, Kevin, University of Central Florida
Abstract / Description: The purpose of this dissertation is to provide a new and improved analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in environmental samples. Hundreds of PAHs and PASHs are present in the environment and have great toxicological importance and the chemical determination of these components is a priority. The complete normal-phase liquid chromatography (NPLC) retention behavior has been explored for these...
Show moreThe purpose of this dissertation is to provide a new and improved analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in environmental samples. Hundreds of PAHs and PASHs are present in the environment and have great toxicological importance and the chemical determination of these components is a priority. The complete normal-phase liquid chromatography (NPLC) retention behavior has been explored for these compounds. Retention indices were determined for 124 PAHs, 62 methyl-PAHs (MePAHs), 67 PASHs, and 80 alkyl-PASHs on an aminopropyl (NH2) stationary phase which represents the most comprehensive study of polycyclic aromatic compounds in normal phase conditions to date. NPLC retention behavior for PAHs and PASHs directly correlated to the total number of aromatic carbons in the parent structures. The normal-phase retention behavior information was used to develop an NPLC fractionation procedure to aid in the sample cleanup for complex environmental matrices which can later be analyzed by gas chromatography/mass spectrometry (GC/MS). Standard Reference Material (SRM) 1597a (complex mixture of PAHs in coal tar), SRM 1991 (coal tar/petroleum extract), and SRM 1975 (diesel particulate extract) were analyzed before and after NPLC fractionation by using GC/MS. In SRM 1597a, the NPLC-GC/MS method allowed for the identification of 72 PAHs, 56 Me-PAHs, 35 PASHs, and 59 alkyl-PASHs. The NPLC-GC/MS procedure also provided the tentative identification of 74 PAHs and 117 MePAHs based on the molecular ion peak only. Furthermore, this method allowed for the following identification breakdown: SRM 1991(-)31 PASHs and 58 alkyl-PASHs; and SRM 1975(-)13 PASHs and 25 alkyl-PASHs.Additional work related to the NPLC fractionation of SRM 1597 included the collection of room-temperature fluorescence spectra for the 21 PAHs with molecular mass (MM) 302 Da known to be in SRM 1597a during reversed-phase liquid chromatography (RPLC) separation. Adding spectral features to a chromatographic run provided the tentative identification of 20 PAHs based on retention times and the presence of 18 were confirmed on the basis of spectral profiles. The advancements in liquid chromatography presented in this dissertation via NPLC fractionation along with RPLC stop-flow fluorescence spectra collection shows potential for becoming routine methodologies for PAC determination in complex environmental samples.
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Date Issued: 2018
Identifier: CFE0007190, ucf:52244
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007190

Title: Use of an Activated Magnesium/cosolvent System for the Desorption and Degradation of Polycyclic Aromatic Hydrocarbons and Their Oxygenated Derivatives in Contaminated Soils.
Creator: Elie, Marc, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Campiglia, Andres, Randall, Andrew, University of Central Florida
Abstract / Description: The contamination of soils, with polycyclic aromatic hydrocarbons (PAHs), remains a widespread environmental concern. In the past two decades, many physical, chemical and biological methods have been developed and evaluated for the degradation of PAHs. However, due to their low aqueous solubility, high sorption affinity, hydrophobicity and recalcitrance, the environmental remediation of PAHs in soil continues to be economically challenging. In addition to PAH contamination, the presence of...
Show moreThe contamination of soils, with polycyclic aromatic hydrocarbons (PAHs), remains a widespread environmental concern. In the past two decades, many physical, chemical and biological methods have been developed and evaluated for the degradation of PAHs. However, due to their low aqueous solubility, high sorption affinity, hydrophobicity and recalcitrance, the environmental remediation of PAHs in soil continues to be economically challenging. In addition to PAH contamination, the presence of oxygenated derivatives of PAHs (OPAHs), in soils, has increasingly become a concern due to their greater toxic properties compared to parent PAH compounds. To date, no investigations on OPAH-remediation methods have been presented in the literature. The use of zero-valent metals (ZVMs) has been reported for several halogenated contaminants in solution systems, but the effectiveness of ZVM to degrade sorbed PAHs and OPAHs has been rarely addressed. This present research focuses on the development of a combined technique for the feasible desorption and degradation of PAHs and OPAHs in soils. PAH and OPAH degradation efficiency, using activated magnesium (Mg) metal combined with an ethanol-ethyl lactate cosolvent (1:1 ratio), was initially examined in soil-free systems. This metal/cosolvent system demonstrated adequate degradation (above 80%) for high-molecular-weight (HMW) PAHs, which were subsequently converted into hydroaromatic compounds; while OPAHs were degraded and converted into hydroxylated or hydrogenated derivatives. Further soil-free studies revealed that the degradation rate was affected by the surface or reactive sites of the metal and that optimum degradation efficiency were obtained with Mg ball milled with graphite (Mg/C).In a bench-scale feasibility test, the efficacy of this system was assessed on a soil spiked with a mixture of three HMW PAHs compounds and three OPAHs compounds with amounts ranging from 0.033 mmol to 0.060 mmol. The experimental results show that 2 mL of an ethanol-ethyl lactate solvent mixture resulted in 58% to 85% extraction efficiency for the selected contaminants in 1 g of spiked soil, followed by 64 - 87% degradation efficiency of the extracted contaminants with 4.11 mmol of the activated metal. This activated-Mg/cosolvent system can be considered as a promising alternative method for ex situ remediation of PAH and OPAH-contaminated soils.
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Date Issued: 2012
Identifier: CFE0004533, ucf:49259
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004533

Title: An Evaluation Study of the Effectiveness of Using a Reaction-Based Process for Hydrazine Remediation.
Creator: Oropeza, Cristina, Clausen, Christian, Yestrebsky, Cherie, Miles, Delbert, Elsheimer, Seth, Griffin, Timothy, University of Central Florida
Abstract / Description: Hydrazine (HZ) and monomethylhydrazine (MMH) are used extensively as hypergolic propellants at Kennedy Space Center. These highly reactive fuels are considered highly toxic, and potentially carcinogenic. Consequently, the transport, handling, and disposal of hydrazines is strictly regulated to protect personnel and the environment. Currently, KSC generates large volumes of hydrazine-laden wastewater for disposal. This waste is contained and shipped on public highways for subsequent disposal...
Show moreHydrazine (HZ) and monomethylhydrazine (MMH) are used extensively as hypergolic propellants at Kennedy Space Center. These highly reactive fuels are considered highly toxic, and potentially carcinogenic. Consequently, the transport, handling, and disposal of hydrazines is strictly regulated to protect personnel and the environment. Currently, KSC generates large volumes of hydrazine-laden wastewater for disposal. This waste is contained and shipped on public highways for subsequent disposal by incineration presenting a potentially catastrophic threat to the environment and the general public in the event of an accidental release. Other existing remediation methods include oxidative and reductive pathways as well as biodegradation in fixed film reactors. Each of these methods has associated drawbacks and limitations that make them unsuitable for industrial use. Recently, hydrazine neutralization by reaction with alpha-ketoglutaric acid (AKGA) to form the stabilized pyridazine derivatives PCA and mPCA has been explored. The applicability of this technique for use at KSC has been established and procedural considerations for implementation have been addressed.Experimental evidence based on worst case scenario decontamination processing simulations and reaction characterization has suggested that AKGA can cost effectively function as a drop-in replacement for current neutralizers with minimal modification to existing infrastructure and operating procedures. Further work will be necessary to satisfy permitting requirements and verify that the reaction product stream is non-hazardous in light of limited toxicity data.
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Date Issued: 2011
Identifier: CFE0004148, ucf:49060
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004148

Title: Chemometric Applications to a Complex Classification Problem: Forensic Fire Debris Analysis.
Creator: Waddell, Erin, Sigman, Michael, Belfield, Kevin, Campiglia, Andres, Yestrebsky, Cherie, Ni, Liqiang, University of Central Florida
Abstract / Description: Fire debris analysis currently relies on visual pattern recognition of the total ion chromatograms, extracted ion profiles, and target compound chromatograms to identify the presence of an ignitable liquid according to the ASTM International E1618-10 standard method. For large data sets, this methodology can be time consuming and is a subjective method, the accuracy of which is dependent upon the skill and experience of the analyst. This research aimed to develop an automated classification...
Show moreFire debris analysis currently relies on visual pattern recognition of the total ion chromatograms, extracted ion profiles, and target compound chromatograms to identify the presence of an ignitable liquid according to the ASTM International E1618-10 standard method. For large data sets, this methodology can be time consuming and is a subjective method, the accuracy of which is dependent upon the skill and experience of the analyst. This research aimed to develop an automated classification method for large data sets and investigated the use of the total ion spectrum (TIS). The TIS is calculated by taking an average mass spectrum across the entire chromatographic range and has been shown to contain sufficient information content for the identification of ignitable liquids. The TIS of ignitable liquids and substrates, defined as common building materials and household furnishings, were compiled into model data sets. Cross-validation (CV) and fire debris samples, obtained from laboratory-scale and large-scale burns, were used to test the models. An automated classification method was developed using computational software, written in-house, that considers a multi-step classification scheme to detect ignitable liquid residues in fire debris samples and assign these to the classes defined in ASTM E1618-10. Classifications were made using linear discriminant analysis, quadratic discriminant analysis (QDA), and soft independent modeling of class analogy (SIMCA). Overall, the highest correct classification rates were achieved using QDA for the first step of the scheme and SIMCA for the remaining steps. In the first step of the classification scheme, correct classification rates of 95.3% and 89.2% were obtained for the CV test set and fire debris samples, respectively. Correct classifications rates of 100% were achieved for both data sets in the majority of the remaining steps which used SIMCA for classification. In this research, the first statistically valid error rates for fire debris analysis have been developed through cross-validation of large data sets. The error rates reduce the subjectivity associated with the current methods and provide a level of confidence in sample classification that does not currently exist in forensic fire debris analysis.
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Date Issued: 2013
Identifier: CFE0004954, ucf:49586
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004954

Title: Folate conjugated hyperbranched polyester nanoparticles for prostate tumor-targeted delivery of a cytotoxic peptide via prostate specific membrane antigen.
Creator: Flores-Fernandez, Orielyz, Perez Figueroa, J. Manuel, Campiglia, Andres, Yestrebsky, Cherie, Harper, James, Khaled, Annette, University of Central Florida
Abstract / Description: Prostate Cancer is the second most deadly cancer in men, after lung cancer. The need for new and effective therapeutics that can constrain prostate cancer progression are challenged by the lack of suitable delivery strategies that target prostate cancer tissue. To study CT20p as potential chemotherapeutic agent in the treatment of prostate cancer we proposed the use of targetable hyperbranched polyester (HBPE) based nanoparticles as delivery system. Folic acid was conjugated to the...
Show moreProstate Cancer is the second most deadly cancer in men, after lung cancer. The need for new and effective therapeutics that can constrain prostate cancer progression are challenged by the lack of suitable delivery strategies that target prostate cancer tissue. To study CT20p as potential chemotherapeutic agent in the treatment of prostate cancer we proposed the use of targetable hyperbranched polyester (HBPE) based nanoparticles as delivery system. Folic acid was conjugated to the nanocarrier to improve the selectivity of the nanoparticle towards specific cell surface targets in prostate cancer cell lines. Specifically we evaluated LNCaP that up-regulated the PSMA receptor. The synthesis of folate conjugated hyperbranched polyester nanoparticles was accomplished using an aliphatic and biodegradable hyperbranched polyester (HBPE). HBPE was prepared from commercially available diethyl malonate and 4-bromobutyl acetate. Our AB2 type monomer displays a three-bond connectivity that grows three-dimensionally under specific polymerization conditions. The product, HBPE, is a polymer with globular configuration that contains surface carboxylic acid groups and holds hydrophobic cavities. Carboxylated HBPE nanoparticles were synthesized via solvent diffusion method. A variety of hydrophobic cargos including: dyes (DiR and DiI) and the cytotoxic peptide CT20p were successfully encapsulated. DLS along with STEM imaging reveal nanoparticle preparations with ~100 nm size. Using water-soluble carbodiimide chemistry, surface modifications were accomplished. Available carboxylic acid groups were conjugated to aminated folic acid to yield folate functionalized nanoparticles.We explore the targeting capability of the Folate-HBPE nanoparticles and demonstrated that the cell internalization of Folate-HBPE into prostate cancer cell lines (LNCaP and PSMA (+) PC-3) was attained via a PSMA-mediated targeting mechanism. Furthermore, when CT20p was delivered to PSMA expressing PCa cells, detachment and death was observed; together with a reduction in the levels of ?1 integrin (CD29) expression, an integrin implicate in cell communication and cell adhesion. CT20p inhibits cell proliferation within 24 h and produce significant cell death after 48 h post treatment. The IC50 of CT20p was calculated at ~7 nM. Additionally, we investigated the capability of Folate-HBPE(CT20p) to perform as a therapeutic agent, in an in vivo setup, using a murine prostate tumor model. The Folate-PEG-HBPE NPs protected CT20p while in circulation and allowed effective uptake by PSMA-mediated targeting. Treatment with Folate-HBPE(CT20p) display localize tumor targeting and significant tumor growth inhibition in PSMA(+) PCa cell lines within days. Together these results suggest the potential of Folate-HBPE(CT20p) nanoparticles in the treatment of prostate cancer.
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Date Issued: 2015
Identifier: CFE0006216, ucf:51112
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006216

Title: Investigation of a Novel Magnesium and Acidified Ethanol System for the Degradation of Persistent Organic Pollutants.
Creator: Maloney, Phillip, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Frazer, Andrew, Quinn, Jacqueline, University of Central Florida
Abstract / Description: For centuries chemists have sought to improve humankind's quality of life and address many of society's most pressing needs through the development of chemical processes and synthesis of new compounds, often with phenomenal results. Unfortunately, there also are many examples where these chemicals have had unintended, detrimental consequences that are not apparent until years or decades after their initial use. There are numerous halogenated molecules in this category that are globally...
Show moreFor centuries chemists have sought to improve humankind's quality of life and address many of society's most pressing needs through the development of chemical processes and synthesis of new compounds, often with phenomenal results. Unfortunately, there also are many examples where these chemicals have had unintended, detrimental consequences that are not apparent until years or decades after their initial use. There are numerous halogenated molecules in this category that are globally dispersed, resistant to natural degradation processes, bioaccumulative, and toxic to living organisms. Chemicals such as these are classified as persistent organic pollutants (POPs), and due to their negative environmental and health effects, they require safe, effective, and inexpensive means of remediation.This research focuses on the development and optimization of a reaction matrix capable of reductively dehalogenating several POPs. Initial experiments determined that powdered magnesium and 1% V/V acetic acid in absolute ethanol was the most effective system for degrading polychlorinated biphenyl (PCB), an extraordinarily recalcitrant environmental contaminant. Further studies showed that this matrix also was capable of degrading polychlorinated dibenzo-p-dioxins (PCDDs), polybrominated diphenyl ethers (PBDEs), and four organochlorine pesticides (OCPs); dieldrin, heptachlor, heptachlor epoxide, and chlordane. During this phase of testing, field samples contaminated with chlordane were washed with ethanol and this ethanol/chlordane solution was degraded using the same reaction matrix, thereby demonstrating this technology's potential for (")real-world(") remediation projects. Finally, a set of experiments designed to provide some insight into the mechanism of dechlorination seems to indicate that two distinct processes are necessary for degradation to occur. First, the passivated outer layer of the magnesium must be removed in order to expose the zero-valent magnesium core. Next, an electron is transferred from the magnesium to the target molecule, causing the cleavage of the halide bond and the subsequent abstraction of either a hydrogen or proton from a solvent molecule. It is anticipated that an understanding of these fundamental chemical processes will allow this system to be tailored to a wide range of complex environmental media.
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Date Issued: 2013
Identifier: CFE0005109, ucf:50723
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005109

Title: Solid Phase Extraction Room Temperature Fluorescence Spectroscopy for the Direct Quantification of Monohydroxy Metabolites of Polycyclic Aromatic Hydrocarbons in Urine Samples.
Creator: Calimag, Korina Jesusa, Campiglia, Andres, Belfield, Kevin, Yestrebsky, Cherie, Chumbimuni Torres, Karin, Schulte, Alfons, University of Central Florida
Abstract / Description: Polycyclic aromatic hydrocarbons (PAH) are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. Because many of them are highly suspect as etiological agents in human cancer, chemical analysis of PAH is of great environmental and toxicological importance. Current methodology for PAH follows the classical pattern of sample preparation and chromatographic analysis. Sample preparation pre-concentrates PAH, simplifies matrix composition, and...
Show morePolycyclic aromatic hydrocarbons (PAH) are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. Because many of them are highly suspect as etiological agents in human cancer, chemical analysis of PAH is of great environmental and toxicological importance. Current methodology for PAH follows the classical pattern of sample preparation and chromatographic analysis. Sample preparation pre-concentrates PAH, simplifies matrix composition, and facilitates analytical resolution in the chromatographic column. Among the several approaches that exist to pre-concentrate PAH from water samples, the Environmental Protection Agency (EPA) recommends the use of solid-phase extraction (SPE). High-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) are the basis for standard PAH identification and determination. Ultraviolet (UV) absorption and room temperature fluorescence detection are both widely used in HPLC, but the specificity of these detectors is modest. Since PAH identifi(&)#172;cation is solely based on retention times, unambiguous PAH identification requires complete chromatographic resolution of sample components. When HPLC is applied to (")unfamiliar(") samples, the EPA recommends that a supporting analytical technique such as GC-MS be applied to verify compound identification and to check peak-purity HPLC fractions. Independent of the volume of extracted water, the approximate time required to separate and determine the sixteen (")priority pollutants(") (EPA-PAH) via HPLC is approximately 60min. If additional GC-MS analysis is required for unambiguous PAH determination, the total analysis time will reach 2-3 hours per sample. If the concentrations of target species are found to lie outside the detector's response range, the sample must be diluted and the process repeated. These are important considerations when routine analysis of numerous samples is contemplated. Parent PAH are relatively inert and need metabolic activation to express their carcinogenicity. By virtue of the rich heterogeneous distribution of metabolic products they produce, PAH provide a full spectrum of the complexity associated with understanding the initial phase of carcinogenesis. PAH metabolites include a variety of products such as expoxides, hydroxyl aromatics, quinines, dihydrodiols, dioepoxides, tetrols and water soluble conjugates. During the past decades tremendous efforts have been made to develop bio-analytical techniques that possess the selectivity and sensitivity for the problem at hand. Depending on the complexity of the sample and the relative concentrations of the targeted metabolites, a combination of sample preparation techniques is often necessary to reach the limits of detection of the instrumental method of analysis. The numerous preparation steps open ample opportunity to metabolite loss and collection of inaccurate data. Separation of metabolites has been accomplished via HPLC, capillary electrophoresis (CE) and GC-MS. Unfortunately, the existence of chemically related metabolic products with virtually identical fragmentation patterns often challenges the specificity of these techniques. This dissertation presents significant improvements in various fronts. Its first original component (-) which we have named solid-phase nano-extraction (SPNE) - deals with the use of gold nanoparticles (Au NPs) as extracting material for PAH. The advantages of SPNE are demonstrated for the analysis of PAH in water samples via both HPLC1 and Laser-Excited Time-Resolved Shpol'skii Spectroscopy (LETRSS).2 The same concept is then extended to the analysis of monohydroxy-PAH in urine samples via SPE- HPLC3 and In-Capillary SPNE-CE.4 The second original component of this dissertation describes the application of Shpol'skii Spectroscopy to the analysis of polar PAH metabolites. The outstanding selectivity and sensitivity for the direct analysis of PAH at trace concentration levels has made Shpol'skii spectroscopy a leading technique in environmental analysis.5 Unfortunately, the requirement of a specific guest-host combination - typically a non-polar PAH dissolved in an n-alkane - has hindered its widespread application to the field of analytical chemistry. This dissertation takes the first steps in removing this limitation demonstrating its feasibility for the analysis of polar benzo[a]pyrene metabolites in alcohol matrixes.
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Date Issued: 2013
Identifier: CFE0005141, ucf:50693
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005141

Title: Anthropogenic Organic Chemical Removal from a Surficial Groundwater and Mass Transfer Modeling in a Nanofiltration Membrane Process.
Creator: Jeffery, Samantha, Duranceau, Steven, Lee, Woo Hyoung, Sadmani, A H M Anwar, Yestrebsky, Cherie, University of Central Florida
Abstract / Description: This dissertation reports on research related to trace organic compounds (TrOCs) in surficial groundwater supplies and their subsequent removal from nanofiltration (NF) membranes. The research was conducted along coastal South Florida in cooperation with the Town of Jupiter Water Utilities, Jupiter, FL (Town). The focus of the research was to determine the extent of reclaimed water impacts on surficial groundwater supplies and subsequent effects on the Town's NF water treatment plant. Routine...
Show moreThis dissertation reports on research related to trace organic compounds (TrOCs) in surficial groundwater supplies and their subsequent removal from nanofiltration (NF) membranes. The research was conducted along coastal South Florida in cooperation with the Town of Jupiter Water Utilities, Jupiter, FL (Town). The focus of the research was to determine the extent of reclaimed water impacts on surficial groundwater supplies and subsequent effects on the Town's NF water treatment plant. Routine monitoring of fourteen TrOCs in reclaimed water and at the water treatment facility revealed varying degrees of TrOC detection in the environment. Certain TrOCs, including caffeine and DEET, were detected in a majority of the water sampling locations evaluated in this work. However, subsequent dilution with highly-treated reverse osmosis (RO) permeate from alternative supplies resulted in TrOCs below detection limits in potable water at the point-of-entry (POE). Pilot testing was employed to determine the extent of TrOC removal by NF. Prior to evaluating TrOC removal, hydraulic transients within the pilot process were first examined to determine the required length of time the pilot needed to reach steady-state. The transient response of a center-port NF membrane process was evaluated using a step-input dose of a sodium chloride solution. The pilot was configured as a two-stage, split-feed, center-exit, 7:2 pressure vessel array process, where the feed water is fed to both ends of six element pressure vessels, and permeate and concentrate streams are collected after only three membrane elements. The transient response was described as a log-logistic system with a maximum delay time of 285 seconds for an 85% water recovery and 267 gallon per minute feed flowrate.Eleven TrOC pilot unit experiments were conducted with feed concentrations ranging from 0.52 to 4,500 ?g/L. TrOC rejection was well-correlated with compound molecular volume and polarizability, with coefficient of determination (R2) values of 0.94. To enhance this correlation, an extensive literature review was conducted and independent literature sources were correlated with rejection. Literature citations reporting the removal effectiveness of an additional sixty-one TrOCs by loose NF membranes (a total of 95 data points) were found to be well-correlated with molecular volume and polarizability, with R2 values of 0.72 and 0.71, respectively.Of the TrOC's detected during this research, the anthropogenic solute caffeine was selected to be modeled using the homogeneous solution diffusion model (HSDM) and the HSDM with film theory (HSDM-FT). Mass transfer coefficients, K_w (water) K_s (caffeine), and k_b (caffeine back-transport) were determined experimentally, and K_s was also determined using the Sherwood correlation method. Findings indicate that caffeine transport through the NF pilot could be explained using experimentally determined K_s values without incorporating film theory, since the HSDM resulted in a better correlation between predicted and actual caffeine permeate concentrations compared to the HSDM-FT and the HSDM using K_s obtained using Sherwood applications. Predicted versus actual caffeine content was linearly compared, revealing R2 values on the order of 0.99, 0.96, and 0.99 for the HSDM without FT, HSDM-FT, and HSDM using a K_s value obtained using the Sherwood correlation method. However, the use of the HSDM-FT and the Sherwood number resulted in the over-prediction of caffeine concentrations in permeate streams by 27 percent and 104 percent, respectively.
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Date Issued: 2016
Identifier: CFE0006331, ucf:51545
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006331

Title: Two-Component Covalent Inhibitors (TCCI) of the Human Immunodeficiency Virus Reverse Transcriptase (HIV-RT).
Creator: Ledezma, Carlos, Kolpashchikov, Dmitry, Yestrebsky, Cherie, Hernandez, Florencio, Zhai, Lei, Tatulian, Suren, University of Central Florida
Abstract / Description: The traditional design of nucleoside reverse transcriptase inhibitors (NRTI's) involves the synthesis of chain-terminated nucleoside analogs. HIV-RT has relatively low fidelity which facilitates mutations that confer resistance towards NRTI's, also, drug promiscuity from NRTI's result in various side-effects that lead to poor patient adherence to treatment. We designed and tested two-component covalent inhibitors against HIV-RT. Our inhibitor design results in higher specificity due to its...
Show moreThe traditional design of nucleoside reverse transcriptase inhibitors (NRTI's) involves the synthesis of chain-terminated nucleoside analogs. HIV-RT has relatively low fidelity which facilitates mutations that confer resistance towards NRTI's, also, drug promiscuity from NRTI's result in various side-effects that lead to poor patient adherence to treatment. We designed and tested two-component covalent inhibitors against HIV-RT. Our inhibitor design results in higher specificity due to its binary approach, which has previously been used in biosensing applications, where both components are necessary for therapeutic effect, and lower chances for mutagenesis because of its inhibitory action. The TCCI approach results in up to 93% inhibition of HIV-RT Furthermore, our inhibitor design is highly modular and can be adjusted towards the therapeutic targeting of other biopolymers.
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Date Issued: 2017
Identifier: CFE0006893, ucf:51712
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006893

Title: Degradation of Hexachlorobenzene, Pentachlorophenol and Pentachloroanisole using Activated Magnesium in an Acidified Ethanol/Ethyl Lactate Cosolvent System.
Creator: Garbou, Amel, Yestrebsky, Cherie, Clausen, Christian, Zou, Shengli, Chumbimuni Torres, Karin, Randall, Andrew, University of Central Florida
Abstract / Description: For many centuries, chemists have dedicated many labor-intensive hours to improving the quality of life for mankind by developing synthetic methods for the production of compounds which fulfill the needs and meet the demands of society. However, the innovation of such compounds has frequently come at the cost of detrimental side-effects that do not always present themselves until many years, or even decades, following their initial application. Many compounds in this category come in the form...
Show moreFor many centuries, chemists have dedicated many labor-intensive hours to improving the quality of life for mankind by developing synthetic methods for the production of compounds which fulfill the needs and meet the demands of society. However, the innovation of such compounds has frequently come at the cost of detrimental side-effects that do not always present themselves until many years, or even decades, following their initial application. Many compounds in this category come in the form of globally-distributed halogenated molecules which are toxic to many living organisms, susceptible to bioaccumulation and resistant to biodegradation processes. Such compounds are classified as persistent organic pollutants (POPs), and require safe, sustainable and economically viable remediation techniques due to their destructive effects on organisms and the environment In the work done for this dissertation study, three particular POPs, which can be further classified as Polychlorinated Aromatic Hydrocarbons (PCAHs), were studied: pentachlorophenol (PCP), hexachlorobenzene (HCB) and pentachloroanisole (PCA).Chlorophenols are highly toxic compounds, usually found in soils, water, and effluents resulting from industrial activities. These environmentally-persistent compounds have been found to exhibit probable carcinogenic properties by the United States Environmental Protection Agency and the International Agency for Research on Cancer. The most toxic chlorophenol is PCP, which has a regulated maximum contaminant level (MCL) of 0.03 mg/L in water. Due to the high toxicity of PCP, it is necessary to treat water and soils that have tested positive for concentrations above the MCL. The aim of this work is to demonstrate the capabilities of using ball-milled zero-valent magnesium powder with various amendments, such as acetic acid (as an activator) and ethanol for the dechlorination of PCP. The dechlorination processes of these various combinations wereivcompared in an attempt to determine the most effective system for the degradation of PCP to phenol. Three systems with powerful capabilities of treatment were studied: ball-milled magnesium powder, ball-milled magnesium carbon (Mg/C), and mechanically alloyed magnesium with palladium. The results of these studies indicate that the most rapid and complete PCP dechlorination is achieved using mechanically alloyed Mg/Pd and a matrix consisting of at least 0.02 g Mg0/mL of ethanol and 10 ?L acetic acid/mL of ethanol, in which case 20 ng/?L of PCP was dechlorinated to phenol in approximately 15 min. with a carbon mass balance of 94.89%. Hexachlorobenzene (HCB), like many chlorinated organic compounds, has accumulated in the environment from agricultural and industrial activity. After its introduction as a fungicide in 1945, the extensive use of this toxic chemical has instigated its infiltration into all food types. Prohibition from commercial use was enforced in the United States in 1966 due to animal, and possible human, carcinogenic effects. Because of the health risks and the adverse impact on various ecosystems, remediation of this contaminant is of vital concern. The objective of this study is to evaluate the proficiency of activated-magnesium metal in a protic solvent system to enhance the reductive dechlorination of HCB. Experimental results were compared with those predicted by quantum chemical calculations based on Density Functional Theory (DFT). Multivariate analysis detected complete degradation of HCB within 30 minutes, having a rate constant of 0.222 min-1, at room temperature. Dechlorination was hypothesized to proceed via an ionic mechanism, and the main dechlorination pathways of HCB in 1:1 ethanol/ethyl lactate were HCB ? PCBz ? 1,2,4,5-TCB; 1,3,4,5-TCB ? 1,2,4-TriCB; 1,3,5-TriCB ? 1,4-DiCB; 1,3-DiCB. The direct relationship between the decreasing number of Cl substituents and dechlorination reaction kinetics agrees with the ?G values predicted by the computational model. Therefore, the lowest energy pathway for C-vCl bond dissociation predicted computationally agrees with the experimentally determined kinetic data. The experimental results from these studies have helped to improve our understanding of the dechlorination mechanisms, thereby offering insight into the most efficient pathways for remediation in the environment. This methodology shows promise for the development of an economic and sustainable field application for the treatment of other chlorinated aromatic compounds. In further work, developments will be made in the modification of the system to allow for the implemetation of field-scale applications.Chloroanisoles are compounds that have similar properties to chlorophenols, but have a higher tendency to bioaccumulate and resist degradation because of their lipophilicity. They are not manufactured for commercial use, but exist in equilibrium with chlorophenols in the environment through biological transformation. Due to the toxicity of both compounds, a strategy for remediation is highly sought after. This study has served to develop an approach to meet the needs for this treatment, based on the successful treatment of PCPs using zero-valent magnesium (ZVMg) discussed in Chapter 1. The results of the method, which makes use of ZVMg/C in acidified ethanol, are compared for both target analytes. Both substrates were degraded to less-chlorinated byproducts within the first four hours; however PCP vanished at a faster rate with no detection at seven minutes. The more heavily-chlorinated byproducts showed faster degradation rates for both compounds, which also had 2,4-dichlorinated congeners in common as major byproducts. The mole balances of PCA and PCP were 92.6% and 94.8%, respectively. Further studies were done to enhance degradation kinetics by re-spiking with acetic acid after two weeks. Although complete degradation was still not achieved, a slight improvement was observed for bothvicompounds, more so with respect to PCP. Kinetic data followed pseudo first-order trends for the degradation of both PCA and PCP.
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Date Issued: 2016
Identifier: CFE0006456, ucf:51433
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006456

Title: Integration of Fundamental Research and CER: The Role of Authenticity in Developing Views on the Nature of Teaching, Learning, and Doing Science.
Creator: Donnelly, Julie, Hernandez, Florencio, Del Barco, Enrique, Saitta, Erin, Yestrebsky, Cherie, Underwood, Sonia, University of Central Florida
Abstract / Description: This dissertation is an integration of fundamental research and chemical education. It begins with two nonlinear spectroscopic studies of compounds important to the study of brain chemistry. In Chapter 2, we present a novel method using quantum mechanics for modelling ligand docking and the potential of nonlinear circular dichroism for elucidating the mechanism of cannabinoids docking to their receptor, a contribution to studies of varying psychological effects of cannabinoids. Considering...
Show moreThis dissertation is an integration of fundamental research and chemical education. It begins with two nonlinear spectroscopic studies of compounds important to the study of brain chemistry. In Chapter 2, we present a novel method using quantum mechanics for modelling ligand docking and the potential of nonlinear circular dichroism for elucidating the mechanism of cannabinoids docking to their receptor, a contribution to studies of varying psychological effects of cannabinoids. Considering existent challenges with measuring this phenomenon, in Chapter 3, we evaluate two-photon absorption properties of Thioflavin T (ThT) in varying glycerol/water content solutions and discuss the enhancement of nonlinear absorption due to small micelle formation. Our results represent the potential to enhance the applications of ThT for imaging Amyloid beta plaques in vitro and ex vivo and its potential application in vivo. Next, we consider the benefits of incorporating modern research into the undergraduate curriculum. In Chapter 4, we describe the integration of nonlinear optics into the physical chemistry laboratory in a course-based undergraduate research experience and the effects on student learning and perceptions. In Chapter 5, we expand our impact to secondary students by describing the development and assessment of the Orlando Chemistry Training, Enrichment, and Tutoring (OCTET) camp and its success in conveying chemistry concepts and inspiring students to pursue chemistry. In Chapter 6, we combine the successes of the previous two studies and incorporate a research component into OCTET. We study the effect on participants' views about science and show the impact on their practical knowledge about doing science. Finally, in Chapter 6, we extend the implementation of authentic learning to the classroom, present the implementation of active learning in physical chemistry, and describe students' perceptions. The results presented in this dissertation demonstrate successful integration of fundamental research into education and the powerful impact on all parties.
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Date Issued: 2018
Identifier: CFE0006997, ucf:51620
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006997

PCA (3)	+ -
PCB (3)	+ -
mPCA (3)	+ -
AKGA (2)	+ -
Chemometrics (2)	+ -

Degradation (2)	+ -
Hydrazine (2)	+ -
Remediation (2)	+ -
degradation (2)	+ -
environmental remediation (2)	+ -
forensic science (2)	+ -
magnesium (2)	+ -
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