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Chlorine Absorption Utilizing Caustic Sodium Sulfite, Henry Mcdonald
Chlorine Absorption Utilizing Caustic Sodium Sulfite, Henry Mcdonald
All Theses
A scrubber was required to abate a waste stream containing chlorine gas created in the electrolytic dissolution step of the aqueous polishing process at the Mixed Oxides Fuel Fabrication Facility at Savannah River Site, South Carolina. A method of absorption that utilized caustic sodium sulfite as the scrubbing agent was studied for implementation in the process. This method was found to be highly efficient with respect to process requirements, and it was also found to provide enhanced performance over the more conventional method of chlorine scrubbing which uses only aqueous sodium hydroxide as a reagent. Sulfite provides an additional advantage …
Effects On Hydrogen Adsorption And Activation On Platinum In A Fuel Cell Catalyst, Jack Zhang
Effects On Hydrogen Adsorption And Activation On Platinum In A Fuel Cell Catalyst, Jack Zhang
All Dissertations
Proton exchange membrane fuel cells are a highly efficient source of power generation that is needed to sustain the energy demands of today's more environmentally conscience society. However, the presence of impurities in the hydrogen fuel stream, such as CO, H2S, and NH3 from the steam reforming/partial oxidation of hydrocarbons/methanol, can severely poison the Pt electrocatalyst present in the fuel cell electrode causing degradation in the fuel cell performance. To counter these poisoning effects, fuel cell manufacturers are forced to use higher Pt loadings, which dramatically increases material costs and prevents the successful commercialization of the technology. …
Oxygenate Synthesis During Co Hydrogenation On Cocuzno- Based Catalysts, Yu-Tung Tsai
Oxygenate Synthesis During Co Hydrogenation On Cocuzno- Based Catalysts, Yu-Tung Tsai
All Dissertations
The research of catalytic synthesis of methanol and other higher alcohols from CO hydrogenation has received great attention since 1980s. The focus of this research is to establish a better fundamental insight into heterogeneous metal catalysts for oxygenate (especially alcohol) synthesis by CO hydrogenation.
Co-based catalysts have been reported widely as the high-performance Fischer-Tropsch Synthesis (FTS) catalysts. The solid base, hydrotalcite (HT), using as a support for Co catalysts resulted in higher activity for CO hydrogenation comparing to other supports (pre-calcined hydrotalcite, MgO and Al2O3). The activities of Co/HT reduced at different reduction temperatures (300-600oC) were …
Cellulose Nanocrystals Properties And Applications In Renewable Nanocomposites, Esteban Urena Benavides
Cellulose Nanocrystals Properties And Applications In Renewable Nanocomposites, Esteban Urena Benavides
All Dissertations
Development of novel bio-based nanocomposites is fundamental to reduce the dependence on fossil resources and provide a sustainable future. In light of this global problem, cellulose nanocrystals (CNCs) have raised interest due to their remarkable mechanical properties. Adequate design of nanocomposites requires a fundamental understanding of how the structure affects the mechanical properties of the material. However, contradictory results in the literature have revealed a lack of comprehension of this relationship for CNC based composites. Consequently, this work provides an explanation to unusual results for CNC nanocomposites presented in the literature and demonstrates the ability to achieve property enhancements in …
Design Of Advanced Ion-Exchange Membranes And Their Performance Assessment For Downstream Chromatographic Bioseparations, Bharatkumar Bhut
Design Of Advanced Ion-Exchange Membranes And Their Performance Assessment For Downstream Chromatographic Bioseparations, Bharatkumar Bhut
All Dissertations
This doctoral research focuses on the design, development and characterization of advanced ion-exchange membranes and their performance evaluation as process chromatography media for downstream bioseparations. Chromatography is a widely used unit operation in the biopharmaceutical industry for the downstream purification of protein therapeutics. The rapid developments in biotechnology and the pharmaceutical potential of biomolecules have increased the worldwide demand for protein therapeutics dramatically. Considering that 50−90% of the total cost of bioprocesses is due to the downstream recovery and purification, high-productivity and high-resolution separation techniques that will enable cost-effective production are essential to the biopharmaceutical industry. In recent years, membrane …
Catalysis Of Ethanol Synthesis From Syngas, Jia Gao
Catalysis Of Ethanol Synthesis From Syngas, Jia Gao
All Dissertations
Catalytic synthesis of ethanol and other higher alcohols from CO hydrogenation has been a subject of significant research since the 1980s. The focus of this research is to establish a better fundamental insight into heterogeneous catalysis for CO hydrogenation reactions, in an attempt to design the best catalysts for ethanol synthesis.
It has been reported widely that promoted Rh-based catalysts can exhibit high selectivity to C2+ oxygenates during CO hydrogenation. The doubly promoted Rh-La-V/SiO2 catalysts exhibited higher activity and selectivity for ethanol and other C2+ oxygenates than singly promoted catalysts. The better performance appears to be due to a synergistic …
Prediction Of Liquid Crystalline Content And Molecular Structures Present In Carbonaceous Pitches, Ward Burgess
Prediction Of Liquid Crystalline Content And Molecular Structures Present In Carbonaceous Pitches, Ward Burgess
All Dissertations
ABSTRACT
Previous research at Clemson has shown that multistage, packed column, supercritical extraction (also called dense-gas extraction, or DGE) of petroleum pitches is a promising technique for the production of carbonaceous precursors that can be processed into a variety of carbon products, including activated carbons and high thermal conductivity carbon fibers. As the existence (or lack thereof) of a liquid crystalline phase, or mesophase, plays a key role in establishing the suitability of a potential precursor material for a given application, we developed the SAFT-LC (liquid crystal) equation of state by combining Maier-Saupe theory for multicomponent mixtures with the SAFT …
Process Development For The Fractionation And Isolation Of Corn Fiber Hemicellulose, Justin Montanti
Process Development For The Fractionation And Isolation Of Corn Fiber Hemicellulose, Justin Montanti
All Theses
Corn fiber is a co-product of the corn wet-milling process that holds potential to become a value-added product. A process was developed to fractionate and isolate the hemicellulose B component of corn fiber generated by corn wet milling. The process consisted of pretreatment by soaking in aqueous ammonia (SAA) of starch-free corn fiber followed by enzymatic cellulose hydrolysis, during which the hemicellulose B was solubilized by cleavage into xylo-oligosaccharides. The hemicellulose A and B fractions were separated by adjustment of pH, and the hemicellulose B recovered by precipitation with ethanol.
The pretreatment step resulted in a high retention of major …
Isolating Petroleum Pitch Oligomers Via Multistage Supercritical Extraction, Eduardo Cervo
Isolating Petroleum Pitch Oligomers Via Multistage Supercritical Extraction, Eduardo Cervo
All Dissertations
Petroleum pitches are carbonaceous materials that serve as precursors for advanced carbon products. Because of their highly graphitic nature, such pitches are of particular interest for producing high thermal conductivity carbon fibers for thermal management applications, such as microelectronics packaging for hybrid and plug-in vehicles.
Even though the properties of the final carbon products are impacted by the molecular composition of the starting pitch precursor, a fundamental understanding of this relationship has yet to be established. To this end, dense-gas extraction (DGE), a fractionation technique that allows for the production of pitches of controlled composition for both analytical and rheological …
Liquid-Liquid Equilibrium For Iodine-Hydroiodic Acid-Water Mixtures At Elevated Temperatures And Pressures For The Sulfur-Iodine Cycle, Sarah Mena
All Theses
An alternative scenario to the overdependence on fossil fuels is the use of thermochemical cycles to split water into hydrogen and oxygen. The Sulfur-Iodine (SI) cycle, developed at General Atomics in the mid 1970s, is a leading candidate of international interest for the centralized production of hydrogen from nuclear and/or solar power. For a comprehensive assessment of the SI cycle, thermodynamic data for I2-HI-H2O mixtures at elevated temperatures and pressures have been identified as a basic research need.
The focus of this study was liquid-liquid equilibrium (LLE) measurements for the above system. To carry out the measurements, a continuous-flow apparatus …
The Rheology, Degradation, Processing, And Characterization Of Renewable Resource Polymers, Jason Conrad
The Rheology, Degradation, Processing, And Characterization Of Renewable Resource Polymers, Jason Conrad
All Dissertations
Renewable resource polymers have become an increasingly popular alternative to conventional fossil fuel based polymers over the past couple decades. The push by the government as well as both industrial and consumer markets to go 'green' has provided the drive for companies to research and develop new materials that are more environmentally friendly and which are derived from renewable materials. Two polymers that are currently being produced commercially are poly-lactic acid (PLA) and polyhydroxyalkanoate (PHA) copolymers, both of which can be derived from renewable feedstocks and have shown to exhibit similar properties to conventional materials such as polypropylene, polyethylene, polystyrene, …
Novel Techniques For The Synthesis Of Three-Way Catalytic Converter Support Materials, Prince Anyaba
Novel Techniques For The Synthesis Of Three-Way Catalytic Converter Support Materials, Prince Anyaba
All Dissertations
Current automobiles use catalytic converters, consisting of noble metals on an oxide support, to convert noxious engine exhaust pollutants into less harmful species. The development of mesoporous oxide supports with optimal pore geometries could enable these devises to decrease in size and weight and significantly reduce the metal loadings required to achieve optimal performance. Thus, in this work, I investigated a wide range of techniques for the synthesis of mesoporous oxides to determine if they could be adapted to ceria-zirconia-yttria mixed oxide (CZY) systems, which are the industry standard for the optimal oxide support for catalytic converter applications. Additionally, I …
Surface And Bulk Modification Of Poly(Lactic Acid), Rahul Rasal
Surface And Bulk Modification Of Poly(Lactic Acid), Rahul Rasal
All Dissertations
The major drawbacks of PLA are its poor toughness and lack of readily reactable groups. Unfortunately, typical methods of PLA toughening are associated with significant modulus and/or ultimate tensile strength (UTS) loss. The main objective of this research was to toughen PLA, with minimal modulus and/or UTS loss, and introduce reactive groups into the PLA matrix in one step. Initially, this objective was divided into two separate parts: PLA surface modification followed by toughening.
PLA film was solvent cast from chloroform solution and was surface modified using a sequential two-step photografting approach. Benzophenone was photografted onto the film surface in …
Synthesis And Analysis Of Nano-Thin Polymer Films For Separation Applications, Azadeh Samadi-Dezfouli
Synthesis And Analysis Of Nano-Thin Polymer Films For Separation Applications, Azadeh Samadi-Dezfouli
All Dissertations
This dissertation focuses on the fabrication of uniform polymer nanolayers using surface-initiated polymerization. The kinetics of low temperature surface-initiated atom transfer radical polymerization (ATRP) is discussed in detail. The work is then extended to the surface modification of polymeric membranes to tune the physical and chemical properties of the membranes for gas separations. I discuss how atom transfer radical polymerization might be advantageous compared to some of the techniques that have been proposed in the literature for preparing polymeric membranes for CO2 separation.
The first part of this dissertation describes the synthesis of polystyrene (PS) nanolayers by surface-initiated ATRP at …
Rheological, Thermal And Processing Studies Of Perfluorocyclobutyl (Pfcb) Polymers, Erick Vasquez
Rheological, Thermal And Processing Studies Of Perfluorocyclobutyl (Pfcb) Polymers, Erick Vasquez
All Theses
Polymeric materials are of interest to the fiber optics industry as glass–silica fibers are prone to fracture. However, the thermal resistance properties of current polymeric materials have limited their use in some optical applications including high performance lasers and high speed telecommunication systems. Therefore, it is of interest to develop new polymer materials and systems with enhanced thermal properties and processability for application in optics. This work focuses on the novel Perfluorocyclobutyl (PFCB) polymer systems. PFCB polymers possess characteristics that make them suitable for optics applications including: a low refractive index, high thermal stability and high chemical resistance. However, little …
Kinetics Of Preferential Adsorption And Equilibrium Properties Of Interfacial Layers Formed From Polymer Chains That Tether By Multiple Ends, Jose Alonzo Calderon
Kinetics Of Preferential Adsorption And Equilibrium Properties Of Interfacial Layers Formed From Polymer Chains That Tether By Multiple Ends, Jose Alonzo Calderon
All Dissertations
Due to their ability to straddle phase boundaries, polymer brushes represent a model system for studies of polymer-modified surfaces. The research presented in this dissertation focuses on understanding a special type of polymer brushes formed at the solid-fluid interface by self-assembly of block copolymer chains that have the ability to tether by multiple ends, thus creating loops on the surface. Specifically, I study the self-assembly of a series of poly(2-vinylpyridine)-polystyrene-poly(2-vinylpyridine) (PVP-b-PS-b-PVP) triblock copolymers and PVP-b-PS star block copolymers adsorbed from the selective solvent toluene onto silicon and mica surfaces. The triblock and star copolymers have different molecular weights and PS/PVP …
Real-Time Raman Spectroscopy And Wide-Angle X-Ray Diffraction During Single-Layer And Multi-Layer Blown Film Extrusion, Giriprasath Gururajan
Real-Time Raman Spectroscopy And Wide-Angle X-Ray Diffraction During Single-Layer And Multi-Layer Blown Film Extrusion, Giriprasath Gururajan
All Dissertations
Properties exhibited by blown films are controlled by the microstructure developed during their processing. Therefore, real-time measurement of microstructure during the blown film extrusion can help in better control and optimization of the process needed to obtain desired properties. The objectives of this research were (i) to conduct real-time microstructural measurements during single-layer and multi-layer blown film extrusion of polypropylene (PP) and low-density polyethylene (LDPE) using real-time Raman spectroscopy; (ii) to conduct real-time wide-angle X-ray diffraction (WAXD) during single-layer blown film extrusion of LDPE to obtain crystallinity and orientation values during the process; and (iii) to investigate the effect of …
Formation Of Active Catalytic Sites In Hydrocarbon Synthesis And Reaction, Nattaporn Lohitharn
Formation Of Active Catalytic Sites In Hydrocarbon Synthesis And Reaction, Nattaporn Lohitharn
All Dissertations
Acid and metal catalysis are considerably important in the chemical industry especially, for the production of transportation fuels. Since a serious concern on the world environment has infringed on the restriction of aromatics contained in gasoline, the demand for clean high-octane branched alkanes for gasoline upgrading has significantly increased. This process involves acid catalyzed n-butane isomerization in which n-butane is converted to isobutane, a primary feedstock for the production of high-octane species. In addition, due to the unpredictable price and the limited resource of petroleum fuel derived crude oil, the attention has shifted to synthetic liquid fuels derived from other …
Biodiesel Production From High Free Fatty Acid Content Feedstocks, Kaewta Suwannakarn
Biodiesel Production From High Free Fatty Acid Content Feedstocks, Kaewta Suwannakarn
All Dissertations
Biomass, such as animal fats and grease, is one of the better sources for transportation fuels, e.g. biodiesel. Use of such biomass in the biodiesel synthesis decreases the need for fossil energy, provides an outlet for utilizing the abundant resources effectively and economically, results in a cleaner fuel that is biodegradable, renewable, and non-toxic. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols are the central reactions for the biodiesel production. The focus of this research is to establish a better fundamental insight into heterogeneous catalysis for biodiesel forming reactions, in an attempt to design …
Immobilization Of Biomolecules On Polymer Scaffolds: A Novel Approach, Joshua Barringer
Immobilization Of Biomolecules On Polymer Scaffolds: A Novel Approach, Joshua Barringer
All Theses
In this thesis, I describe the successful development of a procedure for the step-by-step formation of a multi-layer polymer scaffold on a silicon wafer and the characterization of these materials. Also discussed is the development of a procedure for the non-site specific attachment of a biomolecule to the modified silicon wafer, including scaffolds modified via drop-on-demand, DOD, inkjet printing. Ellipsometry, x-ray photoelectron spectroscopy (XPS), FTIR, fluorometry, and static water contact angle measurements are used to study the nanoscale structure and properties of the interfacial, thin film-modified surfaces. Polymers based on 2-vinyl-4,4-dimethylazlactone (VDMA) are used as the platform onto which biomolecules …
An Experimental And Numerical Study Of The Film Casting Process, Kenneth Aniunoh
An Experimental And Numerical Study Of The Film Casting Process, Kenneth Aniunoh
All Dissertations
Film casting is a common industrial process used to produce polymeric films. During film casting, a polymer melt is extruded through a flat die before rapid cooling on a chill roll. The chill roll velocity is faster than the velocity at which the melt exits the die, thus the polymer melt is stretched and oriented in an extensional flow. The material properties and processing conditions have a significant impact on the process and the final thermal/mechanical properties of the film produced.
Optimization of industrial scale film casting processes is still greatly dependent on trial and error methods. Therefore, this work …
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
All Dissertations
Nano-modifiers are typically three orders of magnitude smaller in size than their micro-counterparts. At this scale, interactions between matrix molecules and the nano-modifiers can lead to novel physical and chemical properties of the resulting nanocomposites. Carbon nanofibers (CNFs) are a class of nano-modifiers that has received significant attention recently because they have superior electrical conductivity and mechanical properties with a high aspect ratio (length over diameter). Several recent research studies have focused on enhancing electrical and mechanical performance of composites in the presence of CNFs. However, the influence of CNFs on the structure of the polymer matrix is important in …
Biohydrogen Production By The Hyperthermophilic Bacterium Thermotoga Neapolitana, Xiaohui Yu
Biohydrogen Production By The Hyperthermophilic Bacterium Thermotoga Neapolitana, Xiaohui Yu
All Dissertations
ABSTRACT Thermotoga neapolitana can use different sources of carbon and nitrogen for growth and produces biological hydrogen. Sources of carbon (glucose, sucrose, xylose, xylan, cellulose, cellobiose, starch, corn starch, beet bulp pellet, and rice flour) and nitrogen (yeast extract, fish meal, cottonseed meal, canola meal, linseed meal, and soybean meal) were compared. In the carbon studies, glucose, sucrose, rice flour, and xylan produced similar levels of hydrogen. In the nitrogen studies, Trypticase combined with alternative nitrogen sources can efficiently increases the yield of hydrogen produced by Thermotoga neapolitana. Yeast extract with trypticase as the dual nitrogen sources produced significantly increased …
Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu
Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu
All Dissertations
Biodiesel synthesis from biomass provides a means for utilizing effectively renewable resources, a way to convert waste vegetable oils and animal fats to a useful product, a way to recycle carbon dioxide for a combustion fuel, and production of a fuel that is biodegradable, non-toxic, and has a lower emission profile than petroleum-diesel. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols constitute the synthetic routes to prepare biodiesel from lipid feedstocks. This project was aimed at developing a better understanding of important fundamental issues involved in heterogeneous catalyzed biodiesel forming reactions using mainly model …
Thermodynamic Adsorption Studies Of Peptides On Well-Defined, Surface-Confined Polymers With Applications In Membrane Bioseparations, Nripen Singh
All Dissertations
This dissertation deals with the fundamental studies of peptide adsorption on surfaces modified by surface-confined polymer films, with an application emphasis on membrane bioseparations. In order to understand protein adsorption at a fundamental level, it is important to study the specific residue-level interactions with surfaces. Keeping this idea in view, the present work describes experimental measurements of submolecular-level interaction energies involved in the process of peptide adsorption on polymer films using surface plasmon resonance spectroscopy. Gibbs energy change on adsorption (ΔGad) for tyrosine, phenylalanine, and glycine homopeptides were measured at 25 °C and pH 7 on highly uniform, nanothin polymer …
Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez
Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez
All Dissertations
Biodiesel, defined as 'a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats', is finding favor commercially worldwide. The objective of this study is to evaluate the use of solid catalysts for triglyceride transesterification and carboxylic acid esterification to produce biodiesel fuel.
Processes using mainly homogeneous alkali catalysts (such as NaOH, KOH, and methoxides) have been shown to be effective for biodiesel synthesis when dealing with virgin oil feedstocks. Use of acid catalysts (e.g., H2SO4) becomes important when processing low quality feedstocks that contain appreciable amounts of free fatty acids, such as …
Kinetics Of Surface-Initiated Photoiniferter-Mediated Photopolymerization And Synthesis Of Stimuli-Responsive Polymer Brushes, Santosh Rahane
Kinetics Of Surface-Initiated Photoiniferter-Mediated Photopolymerization And Synthesis Of Stimuli-Responsive Polymer Brushes, Santosh Rahane
All Dissertations
The focus of this research is to understand the kinetic and mechanistic aspects of surface-initiated photoiniferter-mediated photopolymerization (SI-PMP) and exploit the robustness of SI-PMP to synthesize stimuli-responsive polymer brushes. The 'living' characteristics of dithiocarbamate-based photoiniferter-mediated photopolymerization are well documented. However, in this dissertation I show that the growth of poly(methyl methacrylate) (PMMA) brushes by SI-PMP is nonlinear, suggesting loss of radicals during SI-PMP and, in turn, non-living characteristics. Results from kinetic models in conjunction with experimental results suggest that irreversible bimolecular termination reactions are a primary culprit for the loss of radicals during SI-PMP. To overcome this problem of irreversible …
Using Cross-Sectioned Multilayer Polymer Film And Surface Modification To Form Chemically Patterned Substrates , Chun Zhang
Using Cross-Sectioned Multilayer Polymer Film And Surface Modification To Form Chemically Patterned Substrates , Chun Zhang
All Dissertations
Highly layered structures are important to micro- and nanofabrication technologies for understanding and controlling surface structures through manipulation of chemical and physical interactions. The objective of this work was to develop a new approach to create micro- and nanopatterned surfaces using multilayer polymer films of commercially available and inexpensive polymers instead of inorganic substrates. As an example, linear low density polyethylene (LLDPE) and ethylene-co-acrylic acid copolymer (EAA) were used as alternating inert and reactive polymers, respectively. Thin cross-sections of the multilayer molded sheets were prepared by ultra-microtoming.
As a precursor to the multilayer work, surface modification of EAA was conducted …
Investigation Of Flow And Microstructure In Rheometric And Processing Flow Conditions For Liquid Crystalline Pitch, Santanu Kundu
Investigation Of Flow And Microstructure In Rheometric And Processing Flow Conditions For Liquid Crystalline Pitch, Santanu Kundu
All Dissertations
A fundamental understanding of flow and its influence on the microstructure is required to obtain carbon materials with desired properties. The objective of this research was to investigate the flow and microstructural behavior of a synthetic mesophase pitch (AR-HP) in rheometric and processing flow conditions. In addition, simulation studies were performed to establish a frame work for modeling the flow behavior of this complex material in different flow situations.
The steady-shear viscosities obtained from a cone-plate rheometer during increasing rate-sweep experiments exhibited a shear-thinning region (Region I) with a slope of about -0.2 and a plateau (Region II) region. The …
A Study In Pervaporation Of Ethanol/Water Mixtures And Its Applications To Membrane-Aided Distillation, Mikel E. Goldblatt
A Study In Pervaporation Of Ethanol/Water Mixtures And Its Applications To Membrane-Aided Distillation, Mikel E. Goldblatt
All Theses
No abstract provided.