Chemical Engineering Commons^™

Oxidation Of Borides And Carbides With Y2o3 And Ta Additions, Salvador Manuel Rodriguez

Open Access Theses & Dissertations

The study presented here describes an investigation of an oxidation scale of a fully-sintered Y2O3-ZrB2-TiC composite exposed in air at 1173K. Upon oxidation of the boride/carbide, a ZrO2-TiO2 was expected to form similar to the ZrO2-SiO2 dual scale of an oxidized ZrB2-SiC. The 47wt% Y2O3-38wt%ZrB2-16wt%TiC composite formed a dual scale consisting primarily of an Y2O3-ZrO2-TiC inner scale with an outer scale of ZrO2-TiO2-Y2O3.

The samples oxidized with a parabolic layer growth allowing the calculation of the effective diffusion coefficient indicating that the oxidation was controlled by oxygen ingress through primarily the ZrO2-Y2O3 phase. The oxygen potential between the inner layer …

Organic Photovoltaics: A Charge Transfer Perspective In The Study Of Donor-Acceptor Pairs, Marco Olguin

Open Access Theses & Dissertations

The present research involves the study of donor-acceptor (D/A) dyad complexes from a charge transfer energy perspective. The aim is to provide insight and predictive understanding into the charge transfer processes of the molecular-level components in donor-acceptor based organic solar cells using computational methods to describe photochemical processes at the quantum mechanical level within the Density Functional Theory (DFT) approximation. Predictive understanding is anchored in reproducing experimental results, wherein the present work a perturbative excited-state DFT method is described in detail and shown to give CT energies in excellent agreement with benchmark experimental data. With an accurate excited state method …

Structural And Dynamical Properties Of Liquid And Solid Phases Of Ionic Liquids Confined Inside Nanoporous Materials, Ramesh Singh

LSU Doctoral Dissertations

The purpose of this research is to investigate the physical properties of ionic liquids (ILs) confined inside nanopores of different materials and morphologies. We are interested to study the effect of pore material, morphology and addition of organic solvents on the properties of confined ILs. Understanding the behavior of ILs inside nanopores is relevant to potential applications of these systems in electrochemical double layer capacitors (EDLCs) and dye sensitized solar cells (DSSCs). Such a fundamental understanding is also crucial to optimize the synthesis of hard-templated 1D nanostructures (nanorods, nanotubes, nanowires) based on organic salts, which may be imparted properties (e.g., …

Lipid Production From A Louisiana Native Chlorella Vulgaris/Leptolyngbya Sp. Co-Culture For Biofuel Applications, Rong Bai

LSU Doctoral Dissertations

Over the last several decades, microalgae have garnered great interest for biofuel production mainly due to the high lipid productivity and minimum land competition with food crops. In this research, a Louisiana native Chlorella vulgaris/Leptolyngbya sp. co-culture was selected for lipid production. The goal of this work is to improve the lipid productivity and lipid composition of this co-culture via optimizing irradiance and nitrogen levels, lipid extraction method and modeling of pilot photobioreactor (HISTAR). Effects of irradiance and nitrate nitrogen levels on total lipid yield, neutral lipid portion, and fatty acid profile of non-aerated and aerated co-cultures were investigated in …

A Modeling, Optimization, And Analysis Framework For Designing Multi-Product Lignocellulosic Biorefineries, Paritosh Kumar Sharma

LSU Doctoral Dissertations

The objective of this research is to propose a methodology to develop modular decision analysis frameworks to design value chains for enterprises in the renewable fuels and chemicals sector. The decision support framework focuses on providing strategic decision support to startup and new product ventures. The tasks that are embedded in the framework include process and systems design, technology and product selection, forecasting cost and market variables, designing network capacities, and analysis of risks. The Decision support system (DSS) proposed is based on optimization modeling; systems design are carried out using integer programming with multiple sets of process and network …

Efficacy Of Multifunctionalized Saccharide Constructs For The Attenuation Of Amyloid-Beta Toxicity, Dhruva Dilip Dhavale

LSU Doctoral Dissertations

There is evidence that amyloid-beta (Aβ) toxicity is mediated through interactions and binding with neuronal surface sialic acids in Alzheimer’s disease (AD). The binding affinity is higher if the sialic acids are clustered and toxicity of Aβ was attenuated by removal of neuronal sialic acids. Thus, interfering with cell membrane-Aβ binding using biomimetics that could reproduce the clustered sialic acid structure could present us with a potential target for therapeutic intervention in AD. Based on this hypothesis, we developed several multifunctionalized sialic acid labeled chitosan compounds of different valency, or number of sialic acid per chitosan molecule, to attenuate Aβ …

Copper-Cobalt Catalysts For Conversion Of Syngas To Ethanol And Higher Alcohols, Miranda Louise Smith

LSU Doctoral Dissertations

Higher alcohols produced by catalytic conversion of synthesis gas are potential octane enhancers for transportation fuels. Copper-cobalt catalysts have emerged as alternatives to the ethanol-selective, but expensive, rhodium-based ones. The reducibility of the catalyst and the CO adsorption mode are important factors in directing the selectivity of CO hydrogenation toward methanol, hydrocarbons, or higher alcohols. In this study, Cu/SiO2, Co/SiO2, and bimetallic CuCo/SiO2 catalysts, as well as their tin-promoted analogues, were synthesized and characterized by TPR, in situ XRD, in situ XANES, and in situ DRIFTS. Cobalt addition to Cu/SiO2 created an amorphous fraction of CuO that was more easily …

Computer Simulations Of Faceted Nanoparticles And Carbon Nanotubes In Liquid Crystals, Shivkumar Shankar Bale

LSU Doctoral Dissertations

The purpose of this research is to investigate the use of liquid crystals (LCs) to manipulate and organize faceted nanoparticles and carbon nanotubes (CNTs). Computer simulations at different levels of detail are used to study these systems. Results from this project will be relevant for potential applications of these systems in displays, nanoscale electronics, electro-optical switches, and in the development of composites with unique mechanical, thermal and/or electronic properties. In this research, two independent but directly related projects were carried out. In the first part of the research, we investigated the torque that develops when faceted nanoparticles, namely cubes and …

Numerical Study Of Downhole Heat Exchanger Concept In Geothermal Energy Extraction From Saturated And Fractured Reservoirs, Yin Feng

LSU Doctoral Dissertations

Geothermal energy has gained a lot of attention recently due to several favorable aspects such as ubiquitously distributed, renewable, low emission resources while leveraging the advances in the associated technologies such as directional drilling and low enthalpy power generation plant. However, there are still many challenges such as the high initial capital cost of drilling and surface facilities, environmental risk of seismicity due to the induced disequilibrium in the formation, and sustainability of project over designed operational life. Traditional downhole heat exchangers (DHE) could potentially reduce the capital cost and the risk of seismicity, but they are unable to maintain …

A Thermodynamic Framework For The Modeling And Optimization Of Crystallization Processes, David John Widenski

LSU Doctoral Dissertations

Crystallization is a widely used chemical engineering separation unit operation process. Since this technique can produce high purity products it is used for the industrial production of many chemical compounds, such as pharmaceuticals, agrochemicals, and fine chemicals. The production of these products is a multi-million dollar industry. Any methods to improve the production of these products would be highly valued. Thus, the main objective of this work is to target model-based optimal strategies for crystallization operations specifically targeting crystal size and crystal size distribution (CSD). In particular, take the knowledge gained and translate it into an economically and practically feasible …

Synthesis, Characterization, And Testing Of Atomically-Precise Au Clusters Supported On Tio₂ For Co Oxidation, Sarthak Gaur

LSU Doctoral Dissertations

Supported Au catalysts have been studied extensively for CO oxidation. These catalysts are known to catalyze this reaction even at sub-ambient temperatures. While recent literature demonstrates catalytic activity of gold nanoparticles <2 nm, the next stage in fine tuning this catalysis process is to develop gold clusters prepared with atomic precision. Such atomically precise gold catalysts supported on TiO2 hitherto have not been investigated for CO oxidation. The main objective of this work is to synthesize atomically-precise Au38 clusters in a flask-based method using principles of wet chemistry, to characterize these clusters using various advanced spectroscopic techniques, and to test these clusters as potential catalytic materials for CO oxidation. Furthermore, we have tested TiO2-supported Au38 clusters and a commercially purchased Au/TiO2 catalyst for CO oxidation at 30 °C and 60 °C, and used DRIFTS as a probe spectroscopic technique to correlate kinetics with the mechanism occurring on the surface of both catalysts in order to device the mechanistic pathways for CO oxidation. The work reported in this dissertation is the first spectroscopic observation of the phenomena where sulfur may have beneficial effect on the catalytic activity of Au/TiO2 catalysts. Such an interesting observation where sulfur has beneficial effect on catalytic activity of Au/TiO2 catalysts has never been observed in the past. We have also synthesized and tested Fe3O4@Au core-shell nanoparticles supported on TiO2 for CO oxidation. We show for the first time that, core-shell type nanogold catalysts are better suited compared to pure gold nanoparticles for heterogeneous gas phase catalysis of CO oxidation. By conducting comprehensive experiments towards understanding CO oxidation catalysis using X-ray photoelectron spectroscopy, infrared spectroscopy, and temperature programmed reduction, we show that the enhanced catalytic activity is due to a combination of factors ranging from synergistic interaction between Au and Fe, complete removal of organic capping ligands and the presence of metallic gold (Au0) in the active catalyst.

Shape-Shifting Surfaces For Rapid Release And Direct Stamping Of Organized Micro-Tissues, Samuel James Dupont

USF Tampa Graduate Theses and Dissertations

The primary aim of the research in this study is to develop a robust and simple platform for the in vitro organization of cells on surfaces which facilitate rapid cell release and allows for the direct stamping of highly organized micro-tissues. Current approaches towards this goal have been very successful but are lengthy and subject cells to harsh conditions for extended periods of time raising questions regarding cell health and maintenance of physiological state. To address these concerns a platform was developed to allow for rapid cell release by utilizing a release mechanism different from previous work.

Micron-scale structures comprised …

Volume-Phase Transitions In Responsive Photo-Cross-Linked Polymer Network Films, Leena Patra

USF Tampa Graduate Theses and Dissertations

The overall thrust of this project is to gain an insight into a class of surface-tethered cross-linked thin films of poly(N-alkylacrylamides) that display a lower critical solution temperature (LCST).The structure of the alkyl group and the modification of the amide groups determine the LCST and resultant volume-phase transition behavior. The aim of this study involves synthesis and characterization of thin films and to correlate the volume-transition behavior to the structure of the alkyl group. For better understanding the volume-transition behavior, the polymer films are perturbed by the Hofmeister salt series to examine trends between different alkyl groups. While most of …

Effect Of Surfactants And Brine Salinity And Composition On Spreading, Wettability And Flow Behavior In Gas-Condensate Reservoirs, Yu Zheng

LSU Doctoral Dissertations

The well-known condensate blockage problem causes severe impairment of gas productivity as the flowing bottom-hole pressure falls below the dew point in gas-condensate reservoirs. Hence, this study attempts to investigate the concept of modifying the spreading coefficient and wettability using low-cost surfactants in the near wellbore region, to prevent the gas flow problems associated with condensate buildup. This study also examines the effect of brine salinity and composition on wettability, spreading and adhesion in condensate buildup regions, to evaluate the ability of brine salinity/composition for enhanced gas productivity in gas-condensate reservoirs. In this study, experiments were performed at both ambient …

An Experimental Investigation Of The Role Of Small Hydrocarbons And Combustion-Generated Nanoparticles On The Formation And Growth Reactions Of Polycyclic Aromatic Hydrocarbons During The Pyrolysis Of A Model-Fuel And Hydrocarbon Gases, Nimesh Bharat Poddar

LSU Doctoral Dissertations

Polycyclic aromatic hydrocarbons (PAH) are an important class of environmental pollutants formed during fuel combustion or pyrolysis. Therefore, an experimental study has been undertaken to better understand the formation and growth pathways of PAH.

To investigate the efficacy of C₃ species as PAH growth agents in the context of solid fuels, pyrolysis experiments have been performed in an isothermal quartz flow reactor in the temperature range of 700–1000 °C and a fixed residence time of 0.3 s. Experiments are performed with the C₃ hydrocarbon, propyne; with catechol (ortho-dihydroxybenzene), a model-fuel representative of aromatic moieties in coal …

Strategies For Real Time Reservoir Management, Yuanyuan Shuai

LSU Doctoral Dissertations

Real–time reservoir management is developed to manage a shrinking labor force and rising demand on energy supply. This dissertation seeks good strategies for real–time reservoir management. First, two simulator–independent optimization algorithms are investigated: ensemble–based optimization (EnOpt) and bound optimization by quadratic approximation (BOBYQA). Multiscale regularization is applied to both to find appropriate frequencies for well control adjustment. Second, two gathered EnKF methods are proposed to save computational cost and reduce sampling error: gathered EnKF with a fixed gather size and adaptively gathered EnKF. Finally, oil price uncertainty is forecasted and quantified with three price forecasting models: conventional forecasting, bootstrap forecasting …

Meso-Scale Fluidic Devices With Chemical Sensors For Biological Applications, Satya Gowthami Achanta

Doctoral Dissertations

"Molecular oxygen and humidity are some of the major environmental quantities being measured for various industrial and commercial applications. This dissertation focuses on the design, fabrication and characterization of optofluidic biosensor systems for oxygen and humidity quantification using color charge-coupled device (CCD) camera as a photodetector and LED panel as an excitation source. Meso-scale fluidic devices with integrated oxygen and humidity sensors for potential applications to hydrotropic and oxytropic studies of small plant roots have been investigated in this study. Meso-scale sensor platform was fabricated using porphyrine complex as the sensitive dye embedded within Ethyl Cellulose (EC) polymer matrix. Green …

A Methodology For Statistical Propped Fracture Treatment Design In Fluvial Environments, Prue Elizabeth Smith

Doctoral Dissertations

"Treatment design for hydraulic fracturing historically has been deterministic in nature. In a deterministic design, required variables can be determined and are assumed to be laterally continuous. This is difficult for geologic settings in general, but nearly impossible in fluvial geologic environments where the second assumption is violated.

Recent work has employed statistical methods to account for the complexity and heterogeneity in fluvial environments. Statistical design tools have been used to assist with improving the design process in complex fluvial geologic systems. Currently, the statistical design tools must be created using a "trial and error" process, which requires first completing/fracturing …

Updated Eor Screening Criteria And Modeling The Impacts Of Water Salinity Changes On Oil Recovery, Ahmad Aladasani

Doctoral Dissertations

"Developing technologies for enhanced oil recovery (EOR) from existing oil fields would supply the world's energy needs for several decades. The application of EOR in many major oil-producing countries remains in its conceptual stage. Thermal and gas EOR methods achieve high incremental rates; however, their application range has not broadened significantly as they have matured, while the rate at which new, promising EOR methods such as Low-salinity water flooding (LSWF) are being implemented is alarming. Despite, the potential of LSWF its development and application has been hindered by the lack of consensus concerning its recovery mechanism(s). Every oil reservoir has …

Free-Radical Maleation Of Poly(Butylene Adipate-Co-Terephthalate) In Supercritical Carbon Dioxide And Its Effect On The Percolation And Deformation Mechanism Of Layered Silicate Nanocomposites, Alexandria Niemoeller

Doctoral Dissertations

The utilization of compostable polymers such as poly(butylene adipate-co-terephthalate) (PBAT) in single-use packaging applications can mitigate the water, solvents, and energy required for processing plastic waste. PBAT exhibits exceptional elongational properties, but its moderate water vapor permeability and low tensile modulus limit the applications in which PBAT can be employed. In this work, PBAT nanocomposites were produced at various loadings of organically-modified montmorillonite. The secondary structure of nanoparticles formed within the PBAT matrix was evident in the terminal region of the linear viscoelastic response under oscillatory shear, and a percolation threshold was determined to occur at 3.88% clay by weight. …