Chemical Engineering Commons^™

Characterization Of Thermal And Mechanical Properties Of Polypropylene-Based Composites For Fuel Cell Bipolar Plates And Development Of Educational Tools In Hydrogen And Fuel Cell Technologies, Daniel López Gaxiola

Dissertations, Master's Theses and Master's Reports - Open

In this project we developed conductive thermoplastic resins by adding varying amounts of three different carbon fillers: carbon black (CB), synthetic graphite (SG) and multi-walled carbon nanotubes (CNT) to a polypropylene matrix for application as fuel cell bipolar plates. This component of fuel cells provides mechanical support to the stack, circulates the gases that participate in the electrochemical reaction within the fuel cell and allows for removal of the excess heat from the system.

The materials fabricated in this work were tested to determine their mechanical and thermal properties. These materials were produced by adding varying amounts of single carbon …

Production Of Biofuel Intermediates From Woody Feedstocks Via Fast Pyrolysis And Torrefaction, Jordan Lee Klinger

Dissertations, Master's Theses and Master's Reports - Open

The main objective of this research was to investigate pyrolysis and torrefaction of forest biomass species using a micropyrolysis instrument. It was found that 30-45% of the original sample mass remained as bio-char in the pyrolysis temperature range of 500 - 700˚C for aspen, balsam, and switchgrass. The non-char mass was converted to gaseous and vapor products, of which 10-55% was water and syngas, 2-12% to acetic acid, 2-12% to hydroxypropanone, 1-3% to furaldehyde, and 5-15% to various phenolic compounds. In addition, several general trends in the evolution of gaseous species were indentified when woody feedstocks were pyrolyzed. With increasing …

Modeling Small Molecule Elution From A Hydrogel Using A Microfluidic Technique, Stephanie Evans

Master’s Theses

Drug release from a fluid-contacting biomaterial is simulated using a microfluidic device with channels defined by solute-loaded hydrogel. In order to mimic a drug delivery device, a solution of poly(ethylene glycol) diacrylate (PEG-DA), solute, and photoinitiator is cured inside a microfluidic device with a channel through the center ofthe hydrogel. As water is pumped through the channel, solute diffuses out of the hydrogel and into the water. Channel sizes within the devices range from 300 µm to 1000 µm to simulate vessels within the body. The properties of the PEG hydrogel were characterizedby the extent of crosslinking, the swelling ratio, …

Investigation Of The Hygroscopic And Morphological Properties Of Atmospheric Aerosols, Laura Cook

Master’s Theses

The first objective of this thesis was to examine the hygroscopic and morphological nature of various substances through the use of an Environmental Scanning Electron Microscope (ESEM). The hygroscopic growth and changes in morphology for pure-component aerosols were studied for particles greater than 2 µm in size. Hygroscopic growth was observed through changes in relative humidity (RH) and hygroscopic growth curves were created. The second objective of this thesis, the hygroscopic growth of multi-component aerosol mixtures, was studied using Hygroscopic Tandem Differential Mobility Analysis(HTDMA). The size distribution for an aerosol stream was determined before and after the stream was subjected …

Synthesis And Surface Modification Of Cdse And Cds Quantum Dots Exhibiting High Quantum Yield, Jeweliet Yost

Master’s Theses

The thesis investigates the effect of surface treatment with various reducing and oxidizing agents on the quantum yield (QY) of CdSe and CdS quantum dots (QDs). The QDs, as synthesized by the organometallic method, contained defect sites on their surface that trapped photons and prevented their radiative recombination, therefore resulting in adecreased QY. To passivate these defect sites and enhance the QY, the QDs were treated with various reducing and oxidizing agents, including: sodium borohydride (NaBH4), calcium hydride (CaH2), hydrazine (N2H4), benzoyl peroxide (C14H10O4), and tert-butylhydroperoxide (C4H10O2). It was hypothesized that the reducing/oxidizing agents reduced the ligands on the QD …

An Investigation Of Two Ceramic Electron Conductors For Use In Solid Oxide Fuel Cell Anodes, Ian Hasson

Master’s Theses

Conducted work with two potential alternatives to Ni, La0.8Sr0.2Cr0.5Mn0.5 (LSCM) and Sr doped LaVO3 (LSV) to serve as the electron conductor in the anode of solid oxide fuel cells SOFCs.

Photocatalytic Destruction Of Halogenated Organic Compounds In Water With A New Photocatalyst, Mabruka Hadidan

Open Access Theses & Dissertations

In this research, a newly developed high surface area semiconductor porous material was synthesized from potassium titanium niobium mixed oxide (KTiNbO5) to be used as a photo catalyst in the presence of UV light to degrade halogenated organic compounds in water. The goal of the project was to investigate the catalytic activity of the material for its effectiveness in the degradation of the halogenated organic compounds, and it is the first investigation of this new photocatalyst with halogenated compounds. Model compounds dichloromethane, 1-chlorobutane, chlorobenzene, and trifluoroacetic acid in aqueous solutions were tested with the photocatalyst under ultraviolet light irradiation, using …

Designing A Membrane Module For Determining The Permeance Of High Fluxing Membranes And The Testing Rtil-Membranes For Dehumidification., Sikyun Bae

Electronic Theses and Dissertations

Membrane-based gas dehumidification can have technical energy, and economical advantages over other dehumidification technologies. Because, it is simple to install, ease to operate, and take low process cost. Removal of water vapor from gases constitutes a significant expenditure of energy in our society. Dehydration via a membrane process would constitute wide spread energy savings. This thesis explores experimental issues involved with testing Room Temperature Ionic Liquid(RTIL)-membrane for dehumidifying gases. RTIL-membranes or Supported Ionic Liquid Membranes (SILMs) have advantageous performance for the separations of the gas pair CO2/CH4 and CO2/N2. Previous research did not separate the membrane mass transport resistance the …

Melting Point Depression Of Lead-Free Solder By Gold, Julie E. Thomas

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

The Response Of Pseudomonas Aeruginosa Biofilm To The Presence Of A Glass Polyalkenoate Cement Formulated From A Silver Containing Glass, A. Coughlan, M. P. Ryan, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.

A Novel Biodiesel And Glycerol Carbonate Production Plant, Nghi T. Nguyen, Yaşar Demirel

Yaşar Demirel Publications

Crude glycerol is the byproduct of biodiesel production plant and the economic value of glycerol may affect the profitability of the biodiesel production plant. As the production rate of bioglycerol increases, its market values drop considerably. Therefore, conversion of bioglycerol into value-added products can reduce the overall cost, hence, leading to a more economical biodiesel production plant. In a direct carboxylation reaction, CO₂ reacts with glycerol to produce glycerol carbonate and water. This study presents a direct comparison of the economic analysis of the conventional biodiesel production plant and the possible next generation biodiesel-glycerol carbonate production plant. At the …

Using Thermally Coupled Reactive Distillation Columns In Biodiesel Production, Nghi Nguyen, Yaşar Demirel

Yaşar Demirel Publications

Production of ethyl dodecanoate (biodiesel) using lauric acid and methanol with a solid acid catalyst of sulfated zirconia is studied by using two distillation sequences. In the first sequence, the methanol recovery column follows the reactive distillation column. In the second sequence, the reactive distillation and methanol recovery columns are thermally coupled. Thermally coupled distillation sequences may consume less energy by allowing interconnecting vapor and liquid streams between the two columns to elminate reboiler or condenser or both. Here we study the thermally coupled side-stripper reactive distillation and eliminate the condenser of the reactive distillation column. Both the sequences are …

Effect Of Titanium Dioxide Supports On The Activity Of Pt-Ru Toward Electrochemical Oxidation Of Methanol, Roderick E. Fuentes, Brenda L. García, John W. Weidner

Faculty Publications

TiO₂and Nb-TiO₂ were investigated as stable supports for Pt-Ru electrocatalysts towards methanol oxidation. X-ray photo-electron spectroscopy (XPS) data for all these TiO₂-based supports show oxidation states of Ti⁴⁺, with no Ti³⁺, suggesting low electronic conductivity. However, the deposition of metal nanoparticles onto the supports at loadings of 60 wt% metal dramatically increased conductivity, making these electrodes (metal particles + support) suitable for electrochemistry even though the supports have low conductivity. For some of these TiO₂-based supports, the activity of Pt-Ru towards methanol oxidation was excellent, even surpassing the activity …

Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason R. Hattrick-Simpers, Wilbur S. Hurst, Sesha S. Srinivasan, James E. Maslar

Faculty Publications

An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storagematerials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element …

Mechanical Characterization Of Polymer Electrolyte Membrane With Optical Methods, Xinyu Huang, Luis Alva, Jay Neutzler

Faculty Publications

Mechanical properties of polymer electrolyte membrane have important implications in the endurance of many electrochemical energy conversion devices [1]. Mechanical experiments are effective method to reveal discrete damage developed in the membrane by quantifying the change of mechanical strength and toughness. Regular strain measurement methods are overly intrusive to the thin and relatively fragile polymer electrolyte membrane; hence optical-based minimal invasive stress/strain measurement methods are studied.

Single-Particle Model For A Lithium-Ion Cell: Thermal Behavior, Meng Guo, Godfrey Sikha, Ralph E. White

Faculty Publications

The single-particle model presented by Santhanagopalan et al. [ J. Power Sources , 156 , 620 (2006)] is extended to include an energy balance. The temperature dependence of the solid phase diffusion coefficient of the lithium in the intercalation particles, the electrochemical reaction rate constants, and the open circuit potentials (OCPs) of the positive and negative electrodes are included in the model. The solution phase polarization is approximated using a nonlinear resistance, which is a function of current and temperature. The model is used to predict the temperature and voltage profiles in a lithium-ion cell during galvanostatic operations. The single-particle …

A Study On The Use Of Inverse Opals Composed Of Zinc Oxide Aggregate Popcorn Particles To Improve The Efficiency Of Dye- Sensitized Solar Cells, Roger Chang

Dissertations and Theses

"In this work, modifications applicable to the working electrode of a dye--‐sensitized solar cell (DSSC) are explored in order to enhance efficiency. Certain compositional and structural changes to the architecture of the electrode are examined. First, the ZnO nanoparticles that are commonly utilized in DSSCs are replaced with ZnO nanoparticle aggregates, also known as ZnO popcorn particles. Subsequently, electrophoretic deposition (EPD) is used to assemble the popcorn particles into an inverse opal structure. This is a unique application of EPD, which has previously been used to infiltrate nanoparticles (d ≤20nm range) Into opal templates, demonstrating the applicability of the technique …

Diffuse-Charge Dynamics Of Ionic Liquids In Electrochemical Systems, Hui Zhao

Mechanical Engineering Faculty Research

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our …

Thermoelectric Properties Of ZnXInYOX+1.5y Films, Otto J. Gregory, Matin Amani

Chemical, Biomolecular, and Materials Engineering Faculty Publications

Ceramic thin film thermocouples are being developed to replace noble metal thermocouples operating within the harsh environments of advanced turbine engines used for power generation and propulsion. Seebeck coefficients as large as 158 V/°C were determined for indium oxide (In₂O₃) at 950°C and 256 V/°C for zinc oxide ZnO at 1250°C relative to platinum reference electrodes. Because these Seebeck coefficients are appreciably larger than those for metallic thermocouples, alloys in the system indium zinc oxide Zn_xIn_yO_x+1.5y were investigated by cosputtering from high purity ZnO and In₂O₃ targets. Thermocouple …

Characterizations Of Partially Reduced Polyoxometalate Catalysts Using Ammonia Adsorption Microcalorimetry And Methanol Oxidation Studies / By Suresh Babu Bommineni., Suresh Babu Bommineni

Dissertations, Master's Theses and Master's Reports - Open

Phosphomolybdic acid (H₃PMo₁₂O₄₀) along with niobium,pyridine and niobium exchanged phosphomolybdic acid catalysts were prepared. Ammonia adsorption microcalorimetry and methanol oxidation studies were carried out to investigate the acid sites strength acid/base/redox properties of each catalyst. The addition of niobium, pyridine or both increased the ammonia heat of adsorption and the total uptake. The catalyst with both niobium and pyridine demonstrated the largest number of strong sites. For the parent H₃PMo₁₂O₄₀ catalyst, methanol oxidation favors the redox product. Incorporation of niobium results in similar selectivity to redox products but also …