Engineering Commons^™

Investigations Of Cost-Effective Biodiesel Production From High Ffa Feedstock, Lesly N. Lesmes Sanchez

Electronic Thesis and Dissertation Repository

Commercial production of biodiesel from refined vegetable oils has been widely practiced. However, more economic raw materials are required in order to make biodiesel competitive in the fuel market. This is a challenge since low-cost lipid feedstock contains high concentrations of free fatty acids (FFA) and water, which inhibit transesterification. This work investigates new catalyst combinations and method configuration to develop a cost-effective and suitable process utilizing refined canola oil and canola oil with high oleic acid content. Results suggest that potassium carbonate is more tolerant to water in the feed and enhances phase separation when compared to traditional catalyst, …

A Dynamic Optimization Framework With Model Predictive Control Elements For Long Term Planning Of Capacity Investments In A District Energy System, Jose Luis Mojica Velazquez

Theses and Dissertations

The capacity expansion of a district heating system is studied with the objective of evaluating the investment decision timing and type of capacity expansion. District energy is an energy generation system that provides energy, such as heat and electricity, generated at central locations and distributed to the surrounding area. The study develops an optimization framework to find the optimal investment schedule over a 30 year horizon with the options of investing in traditional heating sources (boilers) or a next-generation combined heat and power (CHP) plant that can provide heat and electricity. In district energy systems, the investment decision on the …

A Kinetic Study Of Aqueous Calcium Carbonate, Derek Daniel Harris

Theses and Dissertations

Amorphous calcium carbonate (ACC) precipitation is modeled using particle nucleation, growth, and aggregation. The particles are tracked in terms of their radial size and particle density using direct quadrature method of moments (DQMOM). Four separate nucleation models are implemented and are compared to experimental data. In discord with a recent study, it is shown that classical nucleation, coupled with equilibrium chemistry, is in good agreement with experimental data. Novel nucleation mechanisms are presented which fit the experimental data with slightly greater accuracy. Using equilibrium chemistry it is shown that the equilibrium value of ACC is pKeq = 7.74 at 24C, …

Production Of Lignin-Based Phenolic Resins Using De-Polymerized Kraft Lignin And Process Optimization, Homaira Siddiqui

Electronic Thesis and Dissertation Repository

Commercialization of Lignin-based phenol formaldehyde resins (LPF) has been limited due to the increase in curing temperatures and decrease in adhesive strength of LPF compared to conventional phenolic resins. Lignin depolymerization can increase the reactivity of lignin; however, the effect of lignin molecular weight on curing performance of LPF resins has yet to be investigated. This research work examined the optimization of synthesis parameters including percent substitution of phenol with lignin, formaldehyde- to-phenol ratio (F/P), and Mw of lignin to reduce the curing temperature and increase the adhesive strength of LPF. DSC analysis indicated that lignin with Mw ~1200g/mol resulted …

Molecular Modeling Of Dna For A Mechanistic Understanding Of Hybridization, Terry Jacob Schmitt

Theses and Dissertations

DNA microarrays are a potentially disruptive technology in the medical field, but their use in such settings is limited by poor reliability. Microarrays work on the principle of hybridization and can only be as reliable as this process is robust, yet little is known at the molecular level about how the surface affects the hybridization process. This work uses advanced molecular simulation techniques and an experimentally-parameterized coarse-grain model to determine the mechanism by which hybridization occurs on surfaces and to identify key factors that influence the accuracy of DNA microarrays. Comparing behavior in the bulk and on the surface showed, …

Studies On Microscopic Flow Structure Inside A Rectangular Circulating Fluidized Bed Through Image Analysis, Jingsi Yang

Electronic Thesis and Dissertation Repository

The microscopic flow structure is studied systematically and comprehensively through a visualization system in a narrow rectangular circulating fluidized bed (CFB) transparent Plexiglas riser with a height of 7.6 m and a cross section of 19 mm × 114 mm. A visualization system consisting of a high-speed video camera, a light source, and image processing and analyzing programs is designed and developed to enable the flow structure to be visualized directly and studied quantitatively. FCC particles of 67 μm are used as the bed materials under different operating conditions with superficial gas velocity (U_g) and solids circulation rate …

A Comprehensive Study Of Cd(Ii) Removal From Aqueous Solution Via Adsorption And Solar Photocatalysis, Samindika Athapaththu

Electronic Thesis and Dissertation Repository

As the increase in industrial technology continue to progress, it results in the increase in heavy metal pollution, creating harmful effects on humans, plants, and animals. Since toxic metals do not degrade easily, they accumulate over time, posing greater danger to living organisms. Removal of these heavy metals is therefore, of great importance. Though many research studies successfully utilized UV photocatalysis with TiO₂ catalyst for the removal of Cd²⁺, none have performed the photoreduction of Cd²⁺ under visible light using eosin-y dye-sensitized TiO₂. The objective of the present research is to study the photocatalytic …

Hydrodynamics In Recirculating Fluidized Bed Mimicking The Stripper Section Of The Fluid Coker, Francisco J. Sanchez Careaga

Electronic Thesis and Dissertation Repository

The stripper section of a Fluid Coker^TM consists of a system of baffles (sheds) that enhances the removal of interstitial and adsorbed hydrocarbon vapors from the fluidized coke-particles. Most of the hydrocarbon-vapors released below a stripper shed flow up to the stripper shed, where they may crack and form coke deposits that foul the shed. Extensive fouling changes the shapes of the sheds, makes them thicker and reduces the free-space between the adjacent sheds until downward solids flow is so impaired that the Coker has to be shut down.

The Radioactive Particle Tracking (RPT) technique allows the determination of …

Oxygen-Free Propane Oxidative Dehydrogenation Over Vanadium Oxide Catalysts: Reactivity And Kinetic Modelling, Sameer Ali Al-Ghamdi

Electronic Thesis and Dissertation Repository

Propane conversion to propylene has been the subject of intensive researches. This is due to the increasing demand for propylene. Current propylene production processes suffer from several limitations. Oxidative dehydrogenation (ODH) is a promising alternative technology for propylene production overcoming the drawbacks of current processes. However, selectivity control in ODH is still a challenge preventing it from an industrial application. This is due to the formation of undesired carbon oxides. Thus, the development of a selective catalyst is crucial for the commercialization of ODH. Vanadium oxide catalysts have been proposed as the most active and selective catalyst for propane ODH. …

Treatment Of Combined Sewer Overflows Using Ferrate (Vi), Rohan Gandhi

Electronic Thesis and Dissertation Repository

Prevention of pollution from combined sewer overflows (CSOs) is currently a major concern due to their impact on aquatic and human environment. With the stringent regulations related to the CSOs treatment, it is necessary to develop an efficient, fast and low cost treatment technique that meets the applicable criteria. In this work, the comprehensive study was done to determine the efficiency of ferrate (VI) for the treatment of CSOs. At a Fe (VI) dose of 0.24 mg/l, TCOD, SCOD, TBOD₅, SBOD₅, TSS, VSS, TP, TN and soluble TN removal efficiencies of 71%, 75%, 69%, 68%, 72%, …

Effects Of Biodiesel Concentration On Microbial Deterioration Of Polyethylene In A Simulated Fuel Storage Tank, Juan Manuel Restrepo-Florez

Electronic Thesis and Dissertation Repository

In this study a simulated fuel storage tank was used to investigate the effect of biodiesel concentration on biodegradation of polyethylene. This research is relevant in the field of fuel storage. The simulated storage system consisted of a number of identical conical flasks. Each flask was comprised of two layers, an upper one consisting of a fuel blend of diesel with biodiesel in concentrations ranging from 0 to 100% of biodiesel and the bottom layer containing an aqueous mineral media inoculated with a community obtained from a real fuel storage facility. Polyethylene slabs cut to a specific size were immersed …

Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera

Doctoral Dissertations

In this work, a systematic computational study directed toward developing a molecular-level understanding of gas adsorption and diffusion characteristics in nano-porous materials is presented. Two different types of porous adsorbents were studied, one crystalline and the other amorphous. Physisorption and diffusion of hydrogen in ten iso-reticular metal-organic frameworks (IRMOFs) were investigated. A set of nine adsorbents taken from a class of novel, amorphous nano-porous materials composed of spherosilicate building blocks and isolated metal sites was also studied, with attention paid to the adsorptive and diffusive behavior of hydrogen, methane, carbon dioxide and their binary mixtures. Both classes of materials were …

Membrane And Performance Study In Polymer Electrolyte Membrane Fuel Cells And Hydrogen Bromine Redox Flow Batteries, Yujia Bai

Doctoral Dissertations

This dissertation represents the consideration of the problems of polymer electrolyte membrane fuel cells (PEMFC) and hydrogen-bromine redox flow batteries (RFB). Due to the importance of water management in PEMFCs, all the experiments were strictly controlled at different water hydration conditions. Water uptake and densities were measured for Nafion^® and a series of 3M ionomer membranes. The thermodynamics of water and polymer was analyzed based on water uptake experiment and calorimetry. Furthermore, partial molar volumes (PMV) of water/membrane system was defined for the first time and used to analyze the interaction between water and polymers. Three states of water …

A Study About Aqueous Reversible Air Electrode- Catalyst, Electrolyte And Structure, Ming Qi

Doctoral Dissertations

Developing a better high energy density rechargeable battery has becoming critically important for several industries. For building such kind of battery, reversible air electrode has been widely accepted as one of the key components. One of the major challenges for reversible air electrode is finding a good bifunctional catalyst to greatly reduce the recharge overpotential and increase the system efficiency. To achieve this goal, a new air battery chemistry based on cobalt salen modified Au catalyst is proposed in this dissertation as a very promising solution. The unique catalytic activity of this catalyst is found to be a two electron …

Development Of A Monitoring Framework For The Detection Of Diversion Of Intermediate Products In A Generic Natural Uranium Conversion Plant, Jennifer L. Ladd-Lively

Doctoral Dissertations

The objective of this work is the development of an on-line monitoring and data analysis framework that could detect the diversion of intermediate products such as uranium dioxide, uranium tetrafluoride, and uranium hexafluoride in a natural uranium conversion plant (NUCP) using a multivariate statistical approach. This was an initial effort to determine the feasibility of this approach for safeguards applications. This study was limited to a 100 metric ton of uranium (MTU) per year NUCP using the wet solvent extraction method for the purification of uranium ore concentrate. A key component in the multivariate statistical methodology was the Principal Component …

Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He

Doctoral Dissertations

Improving the durability and utilization efficiency of the platinum-on-carbon (Pt/C) catalyst is of vital importance to the commercialization of the polymer electrolyte membrane fuel cell (PEMFC). This body of work provides molecular level insights to aid the fulfillment of this goal. Chapter 1 describes the use of molecular dynamics (MD) simulation in an effort to understand the Pt/C degradation issue from the nano-adhesion point of view. The roles of catalyst nanoparticle size, shape, Pt/C surface oxidation and the extent of ionomer film hydration are investigated to study their effects on nano-particle adhesion. It is found that the adhesion force strengthens …

A Tale Of Two Protein Switches: Engineering, Characterizing, And Understanding A Novel And A Natural Switch, James Vincent Price

Doctoral Dissertations

Throughout nature, many proteins provide a specific function in response to some input signal (e.g., phosyphorylation, pH, etc.), a process that is oftentimes described as switching a protein “on” or “off.” The advent of protein engineering has allowed for the creation and understanding of chimeric proteins for uses in a number of applications such as therapeutics, biosensors and energy production. Two proteins, hemagglutinin (HA) of fowl plague influenza virus and a chimeric protein comprising a fusion between the LFA-1 I domain and the EF3 and EF4 hands of calmodulin, have been investigated in this dissertation. Both of these proteins undergo …

Characterization Techniques And Electrolyte Separator Performance Investigation For All Vanadium Redox Flow Battery, Zhijiang Tang

Doctoral Dissertations

The all-vanadium redox flow battery (VRFB) is an excellent prospect for large scale energy storage in an electricity grid level application. High battery performance has lately been achieved by using a novel cell configuration with advanced materials. However, more work is still required to better understand the reaction kinetics and transport behaviors in the battery to guide battery system optimization and new battery material development. The first part of my work is the characterization of the battery systems with flow-through or flow-by cell configurations. The configuration difference between two cell structures exhibit significantly different polarization behavior. The battery output can …

Structure, Rheology And Optical Properties Of Plasmonic Fluids, Tao Cong

Dissertations - ALL

Fluids with tunable optical and rheological properties are of fundamental and practical interest. They can be easily processed to manufacture thin films and interfaces for applications such as molecular detection and light trapping in photovoltaics. Cationic surfactants such as cetyl-trimethylammonium bromide have the ability to self assemble with metallic nanoparticles to form a corona or a double-layer vesicular structure. These structures upon further interaction with wormlike micelle fragments are hypothesized to form micelle-nanoparticle elastic networks. In this dissertation, solution phase self-assembly is utilized to uniformly distribute various metallic nanoparticles to produce stable multicomponent plasmonic fluids with remarkable color uniformity. The …

An Experimental And Computational Evaluation Of The Importance Of Molecular Diffusion In Gas Gravity Currents, Jeremy Jac Herman

Graduate Theses and Dissertations

The accidental release of hazardous, denser-than-air gases during their transport or manufacture is a vital area of study for process safety researchers. This project examines the importance of molecular diffusion on the developing concentration field of a gas gravity current released into a calm environment. Questions which arose from the unexpectedly severe explosion in 2005 at Buncefield, England were of particular interest. The accidental overfilling of a large tank with gasoline on a completely calm morning led to a massive open air explosion. Forensic evidence showed that at the time of ignition, a vapor cloud, most of which now appears …

Tin Sensitization For Electroless Plating, Xingfei Wei

Graduate Theses and Dissertations

The tin sensitization process has been used in electroless plating since 1940s Brenner and Riddell developed the electroless plating for surface metallization method. It was found to be an interesting topic to study tin sensitization for chemically controlling metal deposition on different substrates, because the tin sensitization process had critical effects on the electroless plated metal thin films. Nowadays electroless plating metal deposition is still an important method for depositing metals. It has a few advantages over the vapor deposition and electrodeposition method, such as work in an ambient condition, on nonconductive substrates, and without extra power input. Applying electroless …

Formulation And Evaluation Of Resistive Inks For Applications In Printed Electronics, Sughosh Satish Bhore

Masters Theses

In the 21^st century, it has been shown that printing methodologies can be used to print electrically functional devices on a variety of substrates. In comparison to conventional electronic manufacturing methods, printing is a more cost effective and less complex process. The requirements for manufacturing Printed Electronics (PE) components are much more demanding than graphic printing applications due to the additional requirement of easy electron flow. This additional requirement increases the need for print uniformity and layer-to-layer registration to a much higher degree. In this work, hybrid UV-curable, water-based, electrical resistive inks were formulated. Inkjet inks were prepared by …

Synthesis Of Ferrocene Copolymers And Investigation Of Their Electrochemical Properties., Alzharani Ahmed

Electronic Theses & Dissertations

Ferrocene is an organometallic compound. It is a classical metallocene consisting of two cyclopentadienyl rings bound on opposite sides of a central iron atom. Such organometallic compounds are also called sandwich compounds. Ferrocene copolymers have well known electrochemical capabilities. The main objective of this thesis is to synthesize vinyl ferrocene copolymers and test their electrochemical properties in aqueous solutions with different electrolytes (sodium nitrate, sodium perchlorate, and phosphate buffered saline). Vinylferrocene and 3-phenyl[5]ferrocenophane-1,5- dimethylene were synthesized using a Wittig reaction. Both ferrocene monomers were copolymerized with N-ethylmaleimide and N-phenylmaleimide and the resulting polymers were analyzed by Gel Permeation chromatography, IR …

Biodegradation Of Cresols Using Pseudomonas Putida Immobilized In Poly Vinyl Alcohol (Pva) Gel, Riham Mohamed Sorkatti Abu Bakr

Theses

The characteristics and viability of polyvinyl alcohol (PVA) as a support material for biomass immobilization and utilization for the biodegradation of cresols have been evaluated. PVA gel pellets were prepared by repeated freezing-thawing method using different PVA compositions. The porous structures of the PVA pellets were examined using a Compound Microscope and SEM and revealed that the matrix structure and pore size distribution were affected by PVA composition. Mechanical properties of the PVA gel were also characterized to evaluate the PVA integrity as a matrix for immobilizing microbial cells and found to be dependent on the PVA mass composition. The …

Fuctional Properties Of Phthalocyanine Dye Based Inks, Yumeizhi Jia

Masters Theses

Currently, inkjet printing techniques are getting more attention. They have the features of non-contact and additive patterning feasibility, compatibility with different substrates (the materials on which the ink is printed), low temperature processing, and low cost (1) (2). They can be used for patterning solution processable polymers or nanoparticle inks on various substrates including conductive materials, paper and glass (3). The need for proper functional inks is increasing every year. The goal of my work was to formulate a phthalocyanine water based ink, which can work as a dielectric ink. In my research, all the materials which were used to …

Gas Composition Analysis Using Limited Production Data Eagle Ford Case Study, Ryckur K. Shuttler

Honors Theses

No abstract provided.

Developing Process Control Experiments For Undergraduate Chemical Engineering Laboratories, Chase M. Swaffar

Graduate Theses and Dissertations

It is the intent of this work to develop a process control apparatus and series of experiments that will help students visualize the PID (Proportional-Integral-Derivative) control of a process and enhance their understanding of the subject. The apparatus is a computer-controlled PID mixing system that responds quickly to set point changes and process disturbances which are directly observable. The system can easily be simulated with a transfer function model in Matlab's Simulink, so that the controller can be optimized for the desired system response. Four experiments can be conducted with this system including: exploration of system modeling and controller optimization …

Sulfonated Perfluorocyclobutyl (Pfcb) Aryl Ether Polymers: Synthesis, Reactivity, And Characterization For Polymer Electrolyte Applications, Jiyoung Park

All Dissertations

Perfluorocyclobutyl (PFCB) aryl ether copolymers are excellent candidates for proton exchange membrane (PEM) component in PEM fuel cells. Sulfonated PFCB copolymer membranes exhibit not only high chemical/thermal/mechanical stability but also high proton conductivity. In this regard, PFCB aryl ether copolymers were synthesized via thermal step-growth [2 + 2] cyclopolymerization from aryl bis-(trifluorovinyl ether) (TFVE) monomers and oligomers. Experimental and computational studies confirmed that copolymerization of relatively electron-rich and electron-poor TFVE monomers gave selective-segmented copolymers in an one-pot polymerization. After sulfonation, the PFCB copolymers comprising hydrophilic and hydrophobic segments gave membranes with high proton conductivity. Cross-linked membranes of the sulfonated PFCB …

Pyrene Oligomers: Their Isolation, Molecular Characterization, And Phase Behavior, David Esguerra Taborda

All Dissertations

Carbonaceous pitches can serve as attractive precursors for advanced carbon materials such as high thermal conductivity fibers or carbon-carbon composites. Yet the effects of composition and molecular structure on the bulk properties (e.g., mesophase content and melting point) of these precursors remain only partly known, mainly because of the difficulties associated with the isolation, identification, and quantification of the large (i.e., molecular weight (mol wt) > 350-400 Da) polycyclic aromatic hydrocarbon (PAH) oligomers comprising these pitches. In this study, oligomeric fractions were isolated via supercritical extraction (SCE) from two representative pitches: a petroleum pitch (M-50) produced by the thermal polymerization of …

Uv-Assisted Stabilization Of Polyacrylonitrile-Based Carbon Fiber Precursors, Marlon Salvador Morales Sandoval

All Dissertations

Due to their high strength and stiffness coupled with low density, carbon fibers are the preferred reinforcing fibers used in high-performance polymer matrix composites. Consequently, the demand for carbon fibers is expected to grow from 40,000 metric tons to about 150,000 metric tons over the next decade. A large fraction of the increase is anticipated in the industrial sector that is cost-sensitive. Therefore, there is a need for the development of novel processes and precursors to reduce the carbon fiber production cost and expand the use of carbon fibers. This research focuses on the development of an alternative, rapid stabilization …