Chemical Engineering Commons^™

Surface Functionalization Of Crystalline Silicon Substrates, Sri Sai Vegunta

LSU Doctoral Dissertations

In this work, various chemical and electrochemical methods were demonstrated to attach application-specific organic monolayers to crystalline silicon substrates. In one study, alkyl monolayers were anodically electrografted or thermally grafted onto planar (100) silicon substrates using Grignard precursors. The results show electrografted methyl monolayers provide a stable Si-C termination, resisting oxidation on (100) surfaces for approximately 55 days in air. The alkyl termination could provide a potential alternative to defective native oxides and kinetically unstable hydride surfaces. A mechanism involving two electron transfers per grafting event was established for both the thermal and electrochemical routes. In another study, unsaturated organic …

Silicon Nanowire Anode For Lithium-Ion Batteries: Fabrication, Characterization And Solid Electrolyte Interphase, Wanli Xu

LSU Doctoral Dissertations

Depletion of fossil fuels and concerns over CO2 emission have driven the development of electric vehicles (EVs) with high-energy efficiencies and low emissions. Lithium-ion rechargeable batteries, compared to lead acid, nickel cadmium, nickel metal hydroxide, and other popular rechargeable batteries, are considered as the most promising candidates for EVs for their high operating voltage and high energy density. Silicon nanowires are considered as lithium-ion battery anodes for their ultra high capacity at 4200 mAh·g-1 (10× higher than conventional graphite anode), as well as stress accommodation for reversible lithiation and delithiation. Silicon nanowires were fabricated via metal assisted electroless etching, and …

Implications Of Surface Runoff Recharge In Semi-Arid Regions On Groundwater Sustainability, Omar M. Al-Qudah

Open Access Theses & Dissertations

Amargosa Desert, Nevada regional groundwater studies show that the surface runoff infiltration occurring in the arroyos following runoff producing storms, and this infiltration is considered to be a major source of groundwater recharge. Groundwater infiltration through alluvium was investigated in the Amargosa Desert using borehole drill cuttings, groundwater chemistry, and applying a novel method for collecting runoff water. The sampling process included sediment, precipitation, and runoff water. In total, 176 runoff, 182 sediment, and 45 precipitation samples were collected between January, 2009 and January, 2011.Water chemistry, chloride concentrations, and stable isotopes of water collected from specially designed runoff samplers, placed …

Film Cooling Effectiveness And Heat Transfer Near Deposit-Laden Film Holes, Scott Lewis, Brett Barker, Jeffrey P. Bons, Weiguo Ai, Thomas H. Fletcher

Faculty Publications

Experiments were conducted to determine the impact of synfuel deposits on film cooling effectiveness and heat transfer. Scaled up models were made of synfuel deposits formed on film-cooled turbine blade coupons exposed to accelerated deposition. Three distinct deposition patterns were modeled: a large deposition pattern (maximum deposit peak = 2 hole diameters) located exclusively upstream of the holes, a large deposition pattern (maximum deposit peak = 1.25 hole diameters) extending downstream between the cooling holes, and a small deposition pattern (maximum deposit peak = 0.75 hole diameter) also extending downstream between the cooling holes. The models featured cylindrical holes inclined …

Investigation Of An Iron-Based Additive On Coal Pyrolysis And Char Oxidation At High Heating Rates, John M. Sowa, Thomas H. Fletcher

Faculty Publications

Iron-based catalysts have been shown to enhance coal pyrolysis and char oxidation at low to moderate temperatures and heating rates (b1250 K and 1–1000 K/s). Such catalytic activity has not been demonstrated at high heating rates and temperatures approaching pulverized coal combustion applications. The effect of an iron-based additive on coal pyrolysis and char combustion was studied in a flat-flame burner system at high particle heating rates using a Kentucky bituminous coal. Pyrolysis and char reactivity of two treated coals with different catalyst loadings were studied and compared with the untreated coal. The total volatiles yield for the treated coals …

Coal Swelling Model For High Heating Rate Pyrolysis Applications, Randy C. Shurtz, Kolbein K. Kolste, Thomas H. Fletcher

Faculty Publications

Thermal swelling of coal during pyrolysis strongly influences combustion and gasification rates. Coal swelling is known to vary strongly with coal rank, heating rate, and total pressure. New experiments confirm and clarify previous observations that maximum swelling occurs for high-rank bituminous coals at heating rates slightly below 10⁴ K/s. Advanced swelling models based on bubble physics yield good qualitative trends at low heating rates, but they fail to predict observed decreases in coal swelling as particle heating rates increase beyond 10⁴ K/s. An empirical swelling correlation for computational fluid dynamics (CFD) applications that correctly describes experimentally observed trends …

The Effects Of Wind On The Flame Characteristics Of Individual Leaves, Wesley J. Cole, Mckaye H. Dennis, Thomas H. Fletcher, David R. Weise

Faculty Publications

Individual cuttings from five shrub species were burned over a flat-flame burner under wind conditions of 0.75–2.80m s^-1. Both live and dead cuttings were used. These included single leaves from broadleaf species as well as 3 to 5 cm-long branches from coniferous and small broadleaf species. Flame angles and flame lengths were determined by semi-automated measurements of video images. Additional data, such as times and temperatures corresponding to ignition, maximum flame height and burnout were determined using video and infrared images. Flame angles correlated linearly with wind velocity. They also correlated with the Froude number when either the …

Co2 Adsorption On Solid Sorbents, Bingyu Li

Electronic Theses and Dissertations

Sorbent-based CO2 capture technology is considered as one of the potential scientific techniques for mitigating greenhouse gas emission. Major advantages of sorbent based adsorption are its low regeneration energy coupled with the elimination of corrosion and equipment degradation characteristic of amine based solvent CO2 capture systems which are the preferred industrial methods. Different CO2 capture configurations, processes, and operational parameters for different sorbents were revieand summarized. Efficient industrial applications for CO2 capture require that solid sorbents possess an adsorption capacity between 1000-2000µmol/g or more together with a long-term regeneration capacity. Economical consideration necessitates that the cost of CO2 sequestration be …

Understanding And Improving Lithium Ion Batteries Through Mathematical Modeling And Experiments, Rutooj D. Deshpande

Theses and Dissertations--Chemical and Materials Engineering

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary.

One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result …

Mathematical Modeling Of Clostridium Thermocellum’S Metabolic Responses To Environmental Perturbation, Bless Adotey

Theses and Dissertations--Biosystems and Agricultural Engineering

Clostridium thermocellum is a thermophilic anaerobe that is capable of producing ethanol directly from lignocellulosic compounds, however this organism suffers from low ethanol tolerance and low ethanol yields. In vivo mathematical modeling studies based on steady state traditional metabolic flux analysis, metabolic control analysis, transient and steady states’ flux spectrum analysis (FSA) were conducted on C. thermocellum’s central metabolism. The models were developed in Matrix Laboratory software ( MATLAB^® (The Language of Technical Computing), R2008b, Version 7.7.0.471)) based on known stoichiometry from C. thermocellum pathway and known physical constraints. Growth on cellobiose from Metabolic flux analysis (MFA) and Metabolic …

The Stereospecific Hydrogenation And Dehydrogenation Of Rosin And Fatty Acids, Edward O'Brien

LSU Master's Theses

Tall oil is a byproduct of the standard wood pulping process in the paper industry. It is primarily made up of C:18 fatty acids, rosin acids and a minor fraction of neutrals. Normally, tall oil is further distilled into fractions and then hydrogenated or dehydrogenated into different products. In this project, three heterogeneous catalytic methods of producing byproducts of various distilled tall oil fractions were examined at lower temperatures and pressures than the industry norm in an attempt to develop cheaper production processes. Reactions were conducted in stirred batch reactors of different sizes and product compositions were analyzed primarily by …

Catalytic Hydrogenation Of Co To Higher Alcohols, Nachal Devi Subramanian

LSU Doctoral Dissertations

The interest in converting synthesis gas to alcohols and oxygenated fuel additives via CO hydrogenation is growing rapidly due to the increasing rise in oil prices. Among the potential end products, ethanol is desirable since it serves as a clean alternative fuel, a gasoline blend, and a hydrogen carrier to supply fuel cells. The high cost and limited availability of the most active/selective Rh-based catalysts has led to the development of base metal catalysts such as modified Cu-based catalysts. Literature suggests that a combination of Co (or Mn) with Cu can facilitate higher alcohol formation by a non-dissociative adsorption of …

Simulation Of Cell Seeding And Retention In A Disordered Polymeric Scaffold, Tejaswini Narayana

LSU Master's Theses

Historically, bone repair has been performed using materials like metals, ceramics, cements and bioactive glass. The major problem with all these materials is that they do not perform the necessary non-structural functions of bone. Engineered tissue, created by growing bone cells on porous biodegradable material (scaffold), will address this issue with current bone repair techniques. Improving engineered tissue treatments requires a thorough understanding of factors affecting cell seeding and proliferation inside a disordered porous material which is not feasible using current experimental techniques. A model for particle transport in a disordered porous material that can predict the particle deposition pattern …

Investigation Of Solid-State Shear Pulverization Processing Parameters For Polyethylene-Clay Nanocomposites , Ben Aldrich

Honors Theses

Investigates multiple processing parameters, includingpolymer type, filler type, processing technique, severity of SSSP (Solid-state shear pulverization)processing, and postprocessing, of SSSP. HDPE and LLDPE polymers with pristine clay and organo-clay samples are explored. Effects on crystallization, high-temperature behavior, mechanicalproperties, and gas barrier properties are examined. Thermal, mechanical, and morphological characterization is conducted to determine polymer/filler compatibility and superior processing methods for the polymer-clay nanocomposites.

Shale Gas Rock Characterization And 3d Submicron Pore Network Reconstruction, Malek Elgmati

Masters Theses

"Determining shale gas petrophysical properties is the cornerstone to any reservoir-management practice. Hitherto, conventional core analyses are inadequate to attain the petrophysical properties of shale gas at submicron-scale. This study combines interdisciplinary techniques from material science, petrophysics, and geochemistry to characterize different shale gas samples from North America including Utica, Haynesville and Fayetteville shale gas plays. Submicron pore structure, clay mineralogy, wettability and organic matter maturation were investigated to evaluate the petrophysical properties of shale gas rocks and to determine the impact of organic and inorganic matters on wettability alteration for different fracturing fluids on shale gas rocks.

High pressure …

The Feasibility Of Using Bifidobacteria Bifidum (Atcc 700541) For The Production Of Prebiotic Oligosaccharides, Candice Marie Luehrs

Masters Theses

"Galactooligosaccharides (GOS) are prebiotics that are being used to influence intestinal microbiota towards health promoting, beneficial bacteria like bifidobacteria. Natural sources of GOS are not found in suitable levels to achieve the desired health effects so economically viable commercial production methods are important. Enzymatic conversion of lactose to GOS through transgalactosylation is a preferred method since the starting material is inexpensive and readily available. Enzymes used in batch production are purified from fungal or bacterial sources or remain in whole cells cultured for GOS production. Purified or unbound enzymes are single use whereas enzymes retained within whole cells can potentially …

Thermomechanics Of Curves In Space, Pavan Krishna Kanchi

Masters Theses

"Several biological molecules are known to form helices and coiled structures, such as DNA, collagen, bacterial flagella, and proteins. The backbones of such molecules may be modeled as a curve in three dimensions. A variational problem for the functional of the total free energy required to perturb moving curves in space is considered. The total energy of a curve in three dimensions is minimized y with a general intensive energy, which is a function of position, and the invariants, curvature and torsion. Three types of moduli are identified: stretching, bending and torsional moduli. As a result, three independent force balances …

Effects Of A Nickel Reactor Liner And Other Reaction Variables During Supercritical Water Reformation Of Glycerin, Michael S. Stever

Masters Theses

"The non-catalytic reformation of glycerin using supercritical water was conducted in a 400-mL tubular reactor constructed of Haynesʼ Alloy 230. The evaluated parameters for this thesis include water-to-glycerin molar ratios ranging from 3 to 24 and reactor temperatures ranging from 500⁰C to 700⁰C. In addition, experiments were performed using the Haynes' Alloy 230 reactor both without a liner and with a Nickel 201 liner. Space time was maintained at approximately 100 seconds and the reactor pressure was kept constant at 24.1 MPa. The resultant effect on product gas composition and carbon gasification was determined. The product gases consisted of a …

Numerical Simulation Of Relative Permeability Modifier Effect On Oil And Water Production, Murad Mohammedahmed Abdulfarraj

Masters Theses

"Excess water production is one of the most prevalent operational problems that oil companies are facing. Polymers and polymer gels have been used widely to control excess water production for mature oilfields. It is well known that polymers/gels can reduce the permeability to water (Krw) much more than that to oil (Kro). This phenomenon is called disproportionate permeability reduction (DPR) and the polymers or gels that exhibit this behavior are called relative permeability modifier (RPM). When RPMs are placed in reservoir, reduced permeability to water can lead to decreased water production, and sometimes increased hydrocarbon production, therefore prolonging the useful …

Experimental Study Of The Interaction Between Surfactants And Preformed Particle Gels, Farag Awadh Muhammed

Masters Theses

"Gel and surfactant treatment are two principle methods to reduce water production and enhance oil recovery (EOR). However, either method by itself has limitations that can be avoided by combining the two. Gel treatment can improve sweep efficiency but has little effect on micro-displacement efficiency. Surfactants are mainly used to improve displacement efficiency but have little effect on sweep efficiency. This research sought to investigate whether the combination of gel and surfactant treatments can be used to significantly enhance oil recovery while reducing water production for extremely heterogeneous mature reservoirs. A newer trend in gel treatments is preformed particle gels …