Chemical Engineering Commons^™

Electrochemical Synthesis Of Ferrate(Vi) By Anodic Oxidation, Jia-Ju Xu, Jian-Ming Wang, Wei-Hua Yang, Cheng Chen, Jian-Qing Zhang

Journal of Electrochemistry

The ferrate(Ⅵ) was synthesized by electrochemical anodic oxidation. The effects of preparation conditions on the current yield of ferrate(VI) synthesis have been studied in this work. The experimental results showed that grey cast iron as an anodic material is suitable for electrochemical synthesis and NaOH solution as an electrolyte results in a higher current yield than KOH solution. The highest current yield was obtained at a current density (4.54) mA·cm^-2, temperature 20 ℃ and 14 mol·dm^-3 NaOH. In this case, a current yield of 68.5% was obtained by electrolysis for 1 h.

Studies On The Mechanism Of Electroreduction Of Oxalic Acid, Yu-Zhan Li, Xin Liu, Rui-Sheng Hu, Deng-Ping Gu

Journal of Electrochemistry

The electroreduction mechanism of oxalic acid on Pb electrode in Na₂SO₄ solution were investigated using high scan rate cyclic voltammetry and chronoamperometry. The dynamic parameters for the first step electron transter reaction of oxalic acid electroreduction by were determined. The corresponding reduction peak potentials of oxalic acid, glyoxylic acid and glycolic acid in the cyclic voltammogranis obtained in the same condition were compared, and the intermediate reduction products of oxalic acid were suggested. The results showed that oxalic acid is weakly absorbed on the lead electrode.

Template Synthesis Of Highly Ordered Monocrystalline Metal Nanowire Arrays By A Two-Step Ac Electrodeposition, Juan Xiang, Jing-Hua Tian, Zi-Mian Ni, Zhi-Feng Huang, Bo Liu, Zhong-Qun Tian

Journal of Electrochemistry

The monocrystalline metal nanowire arrays were prepared by using a two-step AC electrodeposition in porous anodic aluminum oxide (AAO) template. The growth mechanism of nanowires was discussed. As a result, it has been found that the second voltage pulse has a considerable effect on the pore-filling ratio, the uniformity and the crystal structure, whereas the initial voltage pulse affects only the pore-filling ratio. Using the two-step AC electrodeposition, a highly ordered monocrystalline metal nanowire arrays with a pore-filling ration above 95% can be easily obtained.

Growth Dynamics Of Isotactic Polypropylene Single Crystals During Isothermal Crystallization From A Miscible Polymeric Solvent, Rujul Mehta, Wirunya Keawwattana, Thein Kyu

College of Polymer Science and Polymer Engineering

The present article presents a spatiotemporal growth of isotactic polypropylene (iPP) single crystals, melt crystallized from a polymeric solvent, i.e., poly (ethylene octene) copolymer that is known to be miscible with iPP. Optical and atomic force microscopic investigations reveal that the melt grown single crystals of iPP develop in the form of two parallel rows of crystal lamellae, but these crystals merge at the tips. To elucidate the mechanism of these emerging parallel rows of iPP crystals, a phase field model pertaining to solidification phenomena has been employed that involves a nonconserved crystal order parameter and a chain-tilting angle. This …

Analyzing And Modeling Of Photobioreactors By Combining First Principles Of Physiology And Hydrodynamics, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Mixing in Photobioreactors is Known to Enhance Biomass Productivity Considerably, and Flow Dynamics Play a Significant Role in the Reactor's Performance, as They Determine the Mixing and the Cells' Movement. in This Work We Focus on Analyzing the Effects of Mixing and Flow Dynamics on the Photobioreactor Performance. based on Hydrodynamic Findings from the CARPT(Computer Automated Radioactive Particle Tracking) Technique, a Possible Mechanism for the Interaction between the Mixing and the Physiology of Photosynthesis is Presented, and the Effects of Flow Dynamics on Light Availability and Light Intensity Fluctuation Are Discussed and Quantitatively Characterized. Furthermore, a Dynamic Modeling Approach is …

Studies On Improved Integrated Membrane-Based Chromatographic Process For Bioseparation, Yanke Xu

Dissertations

To improve protein separation and purification directly from a fermentation broth, a novel membrane filtration-cum-chromatography device configuration having a relatively impermeable coated zone near the hollow fiber module outlet has been developed. The integrated membrane filtration-cum-chromatography unit packed with chromatographic beads on the shell side of the hollow fiber unit enjoys the advantages of both membrane filtration and chromatography; it allows one to load the chromatographic media directly from the fermentation broth or lysate and separate the adsorbed proteins through the subsequent elution step in a cyclic process.

Interfacial polymerization was carried out to coat the bottom section of the …

Kinetics Of Ho2 Abstraction Of H Atoms From Hydrocarbons And Thermochemical Properties Of Urethane Monomers And Radicals, Rajul Shah

Theses

SECTION I: Kinetics of HO₂ Abstraction of H Atoms From Hydrocarbons

Structures, internal rotational barriers and ideal gas thermochemical properties, ΔH^°_f98 for representative series of transition states for abstraction of H atoms from primary, secondary and tertiary hydrocarbons by the HO₂ radical, TC-HOOH (1), TCC-HOOH (2), TC₂C-HOOH (3), TC₃C-HOOH (4), TC₂CC-HOOH (5), TC₂CC-HOOHC (6) and TC₃CCC-HOOH (7) are analyzed in this study. Molecular structures and vibrational frequencies are determined at the B3LYP/6-3111G(d,p) density functional level. The S°₂₉₈ and C_p(T) values (300≤T/K≤1500) from vibrational, …

Transcriptome-Based Determination Of Multiple Transcription Regulator Activities In Escherichia Coli By Using Network Component Analysis, Katy Kao, Young-Lyeol Yang, Riccardo Boscolo, Chiara Sabatti, Vwani Roychowdhury, James Liao

Faculty Publications

Cells adjust gene expression profiles in response to environmental and physiological changes through a series of signal transduction pathways. Upon activation or deactivation, the terminal regulators bind to or dissociate from DNA, respectively, and modulate transcriptional activities on particular promoters. Traditionally, individual reporter genes have been used to detect the activity of the transcription factors. This approach works well for simple, non-overlapping transcription pathways. For complex transcriptional networks, more sophisticated tools are required to deconvolute the contribution of each regulator. Here, we demonstrate the utility of network component analysis in determining multiple transcription factor activities based on transcriptome profiles and …

High-Resolution Touch Sensor Could Be Boon To Cancer Surgeons, Others

Department of Chemical and Biomolecular Engineering: News Releases

Lincoln, Neb., June 8, 2006 -- One of the trickiest decisions facing a cancer surgeon today is where to stop cutting. The surgeon doesn't want to stop too soon and leave cancer cells in the patient's body, but he or she also doesn't want to take too many cells and do unnecessary damage to organs. That decision could soon be made much easier, though, thanks to a high-resolution touch sensor developed by chemical engineers at the University of Nebraska-Lincoln that may allow surgeons to tell at the level of a single layer of cells whether or not they have excised …

Teaching Engineering Courses With Workbooks, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: News Releases

Society expects that a modem college education will turn out students who are analytical. intellectually curious, culturally aware, employable, and capable of leadership. Some important skills needed for all degree programs are problem solving, communication (written and oral), team or group work, learning and information processing, and technology. Instructors feel rewarded and satisfied when they sense that they have made a difference in the life of a student.

Teaching Coupled Transport And Rate Processes, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: News Releases

Coupling refers to a flux occurring without its primary thermodynamic driving force; for example, mass flux without a concentration gradient called the thermal diffusion is a well-known coupled process. Coupling also refers to a flux occurring in a direction opposite to the direction imposed by its driving force; for example, a mass flux can occur from a low to a high concentration region and is called the active transport or uphill transport, such as potassium and sodium pumps coupled to chemical energy released by the hydrolysis of adenosine triphosphate (ATP) in biological systems. Although the coupled processes seem to be …

Retention And Viability Characteristics Of Mammalian Cells In An Acoustically Driven Polymer Mesh, Zhaowei Wang, Paul Grabenstetter, Donald L. Feke, Joanne M. Belovich

Chemical & Biomedical Engineering Faculty Publications

A processing approach for the collection and retention of mammalian cells within a high porosity polyester mesh having millimeter-sized pores has been studied. Cell retention occurs via energizing the mesh with a low intensity, resonant acoustic field. The resulting acoustic field induces the interaction of cells with elements of the mesh or with each other and effectively prevents the entrainment of cells in the effluent stream. Experiments involving aqueous suspensions of polystyrene particles were used to provide benchmark data on the performance of the acoustic retention cell. Experiments using mouse hybridoma cells showed that retention densities of over 1.5 × …

Fundamental Chemistry Of U And Pu In The Tbp-Dodecane-Nitric Acid System: Quaterly Report, Kenneth Czerwinski, Byron Bennett

Separations Campaign (TRP)

The speciation of hexavalent U and tetravalent Pu will be examined in the TBP-dodecane- nitric acid systems. This topic is chosen based on data needs for separation modeling identified by the AFCI. Emphasis will be placed on studying the influence of nitrate and acetohydroxamic acid on U and Pu speciation as well as conditions where a third phase forms in the organic phase. The organic phase will be 30 % TBP in dodecane. Equal volumes of aqueous and organic phase will be used. The speciation of the actinides in the aqueous and organic phase will be determined by a number …

Etching With Electron Beam Generated Plasmas, D. Leonhardt, Scott G. Walton, Christopher Muratore, Richard F. Fernsler, R. A. Meger

Chemical and Materials Engineering Faculty Publications

A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen–argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm/min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was …

Effect Of Plasma Flux Composition On The Nitriding Rate Of Stainless Steel, Christopher Muratore, Scott G. Walton, D. Leonhardt, Richard F. Fernsler, David D. Blackwell, R. A. Meger

Chemical and Materials Engineering Faculty Publications

The total ion flux and nitriding rate for stainless steel specimens exposed to a modulated electron beam generated argon-nitrogen plasma were measured as a function of distance from the electron beam axis. The total ion flux decreased linearly with distance, but the nitriding rate increased under certain conditions, contrary to other ion flux/nitriding rate comparisons published in the literature. Variation in ion flux composition with distance was explored with a mass spectrometer and energy analyzer as a possible explanation for the anomalous nitriding rate response to ion flux magnitude. A transition in ion flux composition from mostly N2 1 to …

Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White

Faculty Publications

A mathematical model is presented to predict the performance of a lithium-ion battery. It includes the changes in the porosity of the material due to the reversible intercalation processes and the irreversible parasitic reaction. The model was also extended to predict the capacity fade in a lithium-ion battery based on the unwanted parasitic reaction that consumes Li⁺ along with the changes in the porosities of the electrodes with cycling due to the continuous parasitic side reaction. The model can be used to predict the drop in the voltage profile, change in the state of charge, and the effects of …

Modeling Of Cane Sugar Colorant Removal In Packed-Bed Ion Exchange Columns And An Investigation Into Pretreatment Methods, Bruce Malcolm Ellis

LSU Master's Theses

Cane sugar colorants have been extensively researched but still little is known about their exact compositions. Rather than distinct compounds, they are a mixture of many compounds. Some it is assumed can be classified into the pseudo components that have been defined using gel permeation chromatography, based on molecular weight. The defining of these components has allowed the colorants to be modeled independently, instead of as one lumped color parameter. The measured colored components were modeled using a linear driving force adsorption model, which could be applied in the design process for optimizing the decolorizing capacity of the resins. The …

Development And Integration Of New Processes Consuming Carbon Dioxide In Multi-Plant Chemical Production Complexes, Sudheer Indala

LSU Master's Theses

New, energy-efficient and environmentally acceptable, catalytic processes have been identified that can use excess high purity CO₂ as a raw material from the sources available in a chemical production complex. The chemical complex in the lower Mississippi River Corridor has been used to show how these new plants can be integrated into this existing infrastructure using the Chemical Complex and Cogeneration Analysis System. Eighty six published articles of laboratory and pilot plant experiments were reviewed that describe new methods and catalysts to use CO₂ for producing commercially important products. Reactions have been categorized as hydrogenation reactions; hydrocarbon synthesis …

Laboratory Automation Curriculum At Keck Graduate Institute, James D. Sterling

Business and Information Technology Faculty Research & Creative Works

A novel curriculum in laboratory automation and high-throughput technologies has been developed at the Keck Graduate Institute (KGI) over the past five years as part of the professional master's degree program in applied life sciences. The goal of this curriculum has been four-fold: (1) motivate study by describing the need for automation through several example problems in combinatorial biological discovery, (2) provide elements of fundamental engineering science that are required for the development of the technologies and tools that enable automation, (3) provide opportunities for the students to see and use state-of-the-art instruments, learn about existing industry standards, and to …

A Re-Evaluation Of Geopressured-Geothermal Aquifers As An Energy Resource, Jeremy Scott Griggs

LSU Master's Theses

The search for more efficient and economical forms of energy generation is a continual process. Natural gas production and electricity generation from geopressured-geothermal aquifers is an unconventional hydrocarbon source that has long been unproductive due to its marginal economics and lack of technological certainty. This thesis demonstrates that, based on modern technological competencies and economic constraints, geopressured-geothermal energy now maintains a viable future as an alternative domestic energy source.

Online Heat Transfer Measurement And Analysis For Sugar Mill Evaporators, David Timothy Solberg

LSU Master's Theses

Fouling and scaling in evaporators has been an area of great interest to raw sugar mills for a number of years and many of the mechanisms causing the scale and the rates of scaling are unknown. In an attempt to quantify the scaling rates and measure the scaling, an online model has been developed to model a system of evaporators. Monitoring the heat transfer coefficient as a function of time enabled measurement of the scaling rate by monitoring the heat transfer coefficient as it decreased with time. It is assumed that the scaling on the juice side of the evaporators …

Trajectory And Window Width Predictions For A Cased Hole Sidetrack Using A Whipstock, Harshad Prakash Patil

LSU Master's Theses

The Trackmaster system manufactured by Smith Services consists of a multi-ramped whipstock and a trimill assembly used to perform a sidetrack from a cased well. Smith Services has observed evidence that the trimill assembly may prematurely leave the face of the whipstock and build excess inclination and dogleg severity or may fall into the original well immediately after leaving the end of the whipstock ramp thus creating a need to predict the borehole trajectory for sidetracking operations. The goal of this project was to predict the borehole trajectory and the window profile cut in the casing by the sidetracking equipment …

Evaluation Of New Methods For Processing Drilling Data To Determine The Cause Of Changes In Bit Performance, Jaime Solano

LSU Master's Theses

Drilling operations represent the major cost in finding and developing new petroleum reserves. Poor drilling performance when drilling deep shale and strong rocks, as evidenced by slow rate of penetration (ROP), has a significant detrimental impact on drilling costs. Also, it has been concluded that bit balling is the main cause of low ROP when drilling deep, clay-rich shale with water-based mud. In addition, it is estimated that a potential saving in drilling cost of hundreds of millions of dollars a year can be obtained if bit balling is mitigated and ROP is improved. Several methods have been developed in …

Metal-Doped Rare Earth Oxide Catalysts For Condensations To Ketones, Arvind Karkal Bhat

LSU Master's Theses

Metal-doped supported rare earth oxide catalysts were examined to determine their suitability for the decarboxylative condensation of two carboxylic acids to produce ketones. The catalysts were characterized based on chemisorption tests, coke analysis using thermo-gravimetric analysis and X-ray absorption spectroscopy. Effect of catalyst particle size on rate of reaction was studied for various supported cerium oxide catalysts. Catalysts were tested for activity, selectivity, and stability using isothermal fixed bed reactors. Optimal operating conditions for the production of diisopropyl ketone and methyl nonyl ketone were determined. It was found that supported cerium oxide catalysts effectively catalyzed the condensation of isobutyric acid …

Exploration Of Artificial Multiferroic Thin-Film Heterostructures Using Composition Spreads, K.-S. Chang, M. A. Aronova, C.-L. Lin, M. Murakami, M.-H. Yu, Jason R. Hattrick-Simpers, O. O. Famodu, S. Y. Lee, R. Ramesh, M. Wuttig, I. Takeuchi, C. Gao, L. A. Bendersky

Faculty Publications

We have fabricated a series of composition spreads consisting of ferroelectric BaTiO₃ and piezomagnetic CoFe₂O₄ layers of varying thicknesses modulated at nanometer level in order to explore artificial magnetoelectricthin-film heterostructures. Scanning microwavemicroscopy and scanning superconducting quantum interference device microscopy were used to map the dielectric and magnetic properties as a function of continuously changing average composition across the spreads, respectively. Compositions in the middle of the spreads were found to exhibit ferromagnetism while displaying a dielectric constant as high as ≈120.

Series Solution To The Transient Convective Diffusion Equation For A Rotating Disk Electrode, Shiriram Santhanagopalan, Ralph E. White

Faculty Publications

A series solution to the transient convective diffusion equation for the rotating disc electrode system is presented and compared to previously reported solutions. The solution presented here is for the entire time domain and agrees well with both the short and long time solutions presented earlier in the literature.

Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White

Faculty Publications

Five parameters of a model of a polymer electrolyte membrane fuel cell (PEMFC) cathode (the volume fraction of gas pores in the gas diffusion layer, the volume fraction of gas pores in the catalyst layer, the exchange current density of the oxygen reduction reaction, the effective ionic conductivity of the electrolyte, and the ratio of the effective diffusion coefficient of oxygen in a flooded spherical agglomerate particle to the square of that particle radius) were determined by least-squares fitting of experimental polarization curves. The values of parameters obtained in this work indicate that ionic conduction and gas-phase transport are two …

Analytical Solution For The Impedance Of A Porous Electrode, Sheba Devan, Venkat R. Subramanian, Ralph E. White

Faculty Publications

A macrohomogeneous model is presented for a porous electrode that includes coupled potential and concentration gradients with linear kinetics. The equations are solved to obtain an analytical expression for the impedance of a porous electrode. Complex plane plots are presented that illustrate two well-defined arcs: a kinetic arc and a diffusion arc with their time constants far apart. The effects of parameters such as exchange current density, porosity, diffusion coefficient, thickness, and interfacial area on the impedance spectra are presented. The usefulness of the analytical solution in investigating the effect of solution phase diffusion is also presented.

A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White

Faculty Publications

A model for the simulation of the steady-state impedance response of a polymer electrolyte membrane fuel cell (PEMFC) cathode is presented. The catalyst layer of the electrode is assumed to consist of many flooded spherical agglomerate particles surrounded by a small volume fraction of gas pores. Stefan-Maxwell equations are used to describe the multicomponent gas-phase transport occurring in both the gas diffusion layer and the catalyst layer of the electrode. Liquid-phase diffusion of O2 is assumed to take place in the flooded agglomerate particles. Newman’s porous electrode theory is applied to determine over-potential distributions. © 2004 The Electrochemical Society. All …

Cycle Life Modeling Of Lithium-Ion Batteries, Gang Ning, Branko N. Popov

Faculty Publications

A first-principles-based charge-discharge model was developed to simulate the capacity fade of Li-ion batteries. The model is based on the loss of active lithium ions due to solvent reduction reaction and on the rise of the anode film resistance. The effect of parameters such as exchange current density, depth of discharge (DOD), end of charge voltage, film resistance, and the overvoltage of parasitic reaction were studied quantitatively. The model controls the required DOD by controlling the discharge time and estimates the end of discharge voltages as a function of cycle number.