Chemical Engineering Commons^™

Methanol Electro-Oxidation On Pt-Ru Alloy Nanoparticles Supported On Carbon Nanotubes, Ang Li, Yangchuan Xing

Chemical and Biochemical Engineering Faculty Research & Creative Works

Carbon nanotubes (CNTs) have been investigated in recent years as a catalyst support for proton exchange membrane fuel cells. Improved catalyst activities were observed and attributed to metal-support interactions. We report a study on the kinetics of methanol electro-oxidation on CNT supported Pt-Ru alloy nanoparticles. Alloy catalysts with different compositions, Pt 53Ru 47/CNT, Pt 69Ru 31/CNT and Pt 77Ru 23/CNT, were prepared and investigated in detail. Experiments were conducted at various temperatures, electrode potentials, and methanol concentrations. It was found that the reaction order of methanol electro-oxidation on the PtRu/CNT catalysts was consistent with what has been reported for PtRu …

Synthesis And Characterization For A New Organic Cathode Material Of Lithium-Ion Batteries——Poly Sulfurized Chloranilic Acid(Psca), Kai Liu, Jian-Ming Zheng, Gui-Ming Zhong, Yong Yang

Journal of Electrochemistry

A new organic cathode material,poly sulfurized chloranilic acid(PSCA),has been successfully synthesized for lithium-ion batteries. 13C solid state NMR and FTIR results indicated that the chorine in chronailic acid was substituted by sulfur after sulfurization. The electrochemical measurements showed that the initial discharge capacity of PSCA was up to 287.6 mAh/g,and 169.9 mAh/g still remained after 100 cycles when cycled between 1.5～3.6 V at the current density of 15 mA/g.

A Direct Borohydride Fuel Cell With Fecopc2-Catalysed Cathode, Jin-Fu Ma, Yan Liu, Jun-Hua Lai, Yong-Ning Liu

Journal of Electrochemistry

In this paper,a membraneless direct borohydride fuel cell was investigated. Cyclic voltammograms of FeCoPc₂-modified glassy carbon electrode in the alkaline solution show that FeCoPc₂ was active for oxygen reduction reaction. In addition, the steady-state polarization curve tests indicate that FeCoPc₂ had better activity than FePc,CoPc or FePc+CoPc, which is due to its conjugated effect and synergistic effect of Fe and Co. Finally, a maximum power density of 110 mW/cm² was attained, and the 25-day life test shows that the direct borohydride fuel cell had a good stability.

Electrochemical Reduction Of Nitrobenzene In Different Ionic Liquids, Jun-Li Fan, Wei-Lin Ye, Rong Wang, Li-Qun Xu, Xia-Qin Wu

Journal of Electrochemistry

Electrochemical reduction of nitrobenzene at glassy carbon electrode in different ionic liquids,such as N-methylimidazolium-p-toluene sulfonic acid ([Mim][PhSO₃]) and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF₆]) have been investigated by cyclic voltammetry. Experimental results showed that only a cathodic current peak was observed in [Mim][PhSO₃],which is a diffusional controlled irreversible reaction. And two pairs of current peaks were obtained in [Bmim][PF₆] in the same potential range,indicating showed that the reduction products of nitrobenzene were different in different ionic liquids.

Electrochemical Studies On The Ionic Charge Transfer Properties Of The Oxygen Vacancy Defects In The Oxide Films Formed On Titanium, De-Sheng Kong, Hai-Yan Liu, Wen-Juan Fan, Wen-Hua Lv, Zhang-Yu Yu, Yuan-Yuan Feng

Journal of Electrochemistry

The ionic charge transfer properties of the oxygen vacancy point defects in TiO₂ films formed on titanium were studied in 1.0 mol·L^-1 HClO₄ solution with cyclic voltammetry,potentiostatic polarization,galvanostatic reduction and capacitance measurements. The measured capacitance data were analyzed based on the Mott-Schottky equation and Einstein equation. Based on the different response times to the changes of the applied electric field between the ionic and the electronic charge transfers,the diffusion coefficient of the point defects in the anodic oxide film on titanium was estimated. It was shown that the passive potential region for titanium in 1.0 mol·L^{-1 …}

Synthesis And Characterization Of Sulfur-Carbonnanotubes As Cathode Of Lithium/Sulfur Rechargeable Battery, Rui Du, Zhong-Zhi Yuan

Journal of Electrochemistry

A carbon-containing composite was synthesized by heating element sulfur and carbon nanotubes. The sulfur-carbonnanotube composites were characterized by X-ray diffraction, SEM, Brunauer-Emmett-Teller. The electrochemical property was characterized by cyclic voltammetry,constant current charge and discharge. It was revealed that the sulfur-carbonnanotube cathode 2016-type coin cells exhibited a good electrochemical property with the initial dicharge specific capacity up to 680 mAh/g and a stable capacity approximately 500 mAh/g after 30 cycle numbers.

Tungstate/Pertungstate System Cathodic Indirect Oxidation To Synthesis Hydrophobic Monascus Yellow Colorant, Wen-Jian Chen, Xue-Hong Huang, Zhen Chen, Sheng-Bo Ke, You-Zhen Lin

Journal of Electrochemistry

Using SBS-g-(AA/StSO₃Na)/SBS-g-DMAEMA Bipolar Membrane as a separator between the cathode and anode chambers in the electrolysis cell,the optimum conditions of deoxidization of oxygen in cathode were obtained through orthogonal experiment. Then using tungstate/pertungstate as media to indirect electrooxidate hydrophobic monascus red colorant to prepare hydrophobic monascus yellow colorant in cathode. The experiment results show the average current efficiency of cathode was up to 72.39% under the following conditions:that graphite as electrode,10% sulfuric acid as anode electrolyte,0.5 g·L^-1 hydrophobic monascus red colorant solution as cathode electrolyte,tungstate concentration:15 mmol/L,pH=3,flow rate of oxygen:65 cm³/min,electrolyze 2 h under the …

Electrocatalytic Oxidation Of Glucose On Cnt/Nanocrystlline Tio2-Pt Complex Film Electrode In Ionic Liquids, Dao-Bao Chu, Long-Wu Zha, Shu-Xi Wang, Jian Wang, Ying Xiao, Yuan-Yuan Hou, Jian-Guo He, Xue-Jiao Zhang

Journal of Electrochemistry

Using ionic liquid [EMI]BF₄ as the electrolyte,the electrocatalytic oxidation of glucose on carbon nanotubes/nanocrystlline TiO₂ film loaded on Pt (CNT/nanoTiO₂-Pt) complex film electrode was investigated by cyclic voltammetry. The results found that the CNT/nanoTiO₂-Pt complex electrode had high catalytic activity to the electrochemical oxidation of glucose in ionic liquids and the oxidation potential was -0.46 V. The best effect of glucose oxidation was obtained with the volume ratio of ionic liquid to water being 3:1. The process of electrodic reaction process was concentration polarization controlled.

Ellipsometric Study On Colored Electroplating Of Cuprous Oxide On Ni Substrate, Xue-Song Feng, Jing-Lei Lei, Ai-Xiang Chen, Wan-Shan Yin, Ling-Jie Li, Sha Zheng, Hui Zhao, Shao-Yan Pan

Journal of Electrochemistry

The colored Cu₂O coating was electroplated on Ni substrate to meet the decorative requirements. Results of X-ray photoelectron spectroscopy (XPS) indicate the coating consisting of Cu₂O. Images of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) show that the Cu₂O coating is smooth and uniform,and covers the Ni substrate wholly. Ellipsomtric measurements for Cu₂O coatings with various electroplating time were carried out. Using a 4-layer model of "Air-Cu₂O layer-interphase-Ni" ,the interphase was modeled with the graded effective medium approximation (EMA),the ellipsomtric data were deconvoluted and the Cu₂O …

Controlled Release Of Fluoride From Poly(Ethylene-Co-Vinyl Acetate) Films, Shadeed Khan

Theses and Dissertations

The development of aesthetically unattractive white spots is a concern for patients undergoing fixed orthodontic treatment. Due to poor oral hygiene during treatment, accumulation of plaque around orthodontic brackets causes bacterial fermentation reactions producing acids that dissolve the mineral enamel. Such dissolution results in white spot formation, an early sign of dental caries. In principal, to inhibit the appearance of these spots during treatment, fluoridated elastomeric o-rings might be employed. Once placed around brackets, these o-rings should release fluoride therapeutically for at least 30 days, after which the orthodontist may replace them. At the present time, such fluoride-releasing o-rings are …

Deposition Of Particulate From Coal-Derived Syngas On Gas Turbine Blades Near Film Cooling Holes, Weiguo Ai

Theses and Dissertations

Synfuel from gasification of coal, biomass, and/or petroleum coke is an alternative to natural gas in land-based industrial gas turbines. However, carryover fine particulate in the syngas may lead to a considerable amount of deposition on turbine blades, which reduces component life and system performance. Deposition experiments on film-cooled turbine components were performed in an accelerated test facility to examine the nature of flyash deposits near film cooling holes. Experimental results indicate that deposition capture efficiency decreased with increased blowing ratio. Shaped holes exhibited more span-wise coverage than cylindrical holes and effectively reduced deposition. The TBC layer increased surface temperature, …

Synthesis And Characterization Of Some Rhenium Complexes, Joseph Brian Scott

Masters Theses & Specialist Projects

Plastics or polymers are thought to behave oppositely from metals. Ideally, polymers behave as insulators while metals conduct electricity. Shirakawa and coworkers discovered conductive polymers in 1977.1 These conductor polymers have been extensively studied, discovering that charge transfer oxidative doping of polyacteylene could increase its conductivity by 12 orders of magnitude. Polyacetylene, although showing promise as an organic conductor, because it is highly air-sensitive and oxidizes when exposed to molecular oxygen, therefore making this an unattractive use for commercial products. Attention has been focused on heterocylic aromatic polymers such as polythiophene and polypyrrole, in efforts to produce conductive polymers that …

Chameleon Coatings: Adaptive Surfaces To Reduce Friction And Wear In Extreme Environments, Christopher Muratore, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

Adaptive nanocomposite coating materials that automatically and reversibly adjust their surface composition and morphology via multiple mechanisms are a promising development for the reduction of friction and wear over broad ranges of ambient conditions encountered in aerospace applications, such as cycling of temperature and atmospheric composition. Materials selection for these composites is based on extensive study of interactions occurring between solid lubricants and their surroundings, especially with novel in situ surface characterization techniques used to identify adaptive behavior on size scales ranging from 10−10 to 10−4 m. Recent insights on operative solid-lubricant mechanisms and their dependency upon the ambient environment …

Comparison Of Failure Mechanisms For Cements Used In Skeletal Luting Applications, O. Clarkin, D. Boyd, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass Polyalkenoate Cements (GPCs) based on strontium calcium zinc silicate (Sr-Ca-Zn-SiO₂) glasses and low molecular weight poly (acrylic acid) (PAA) have been shown to exhibit suitable compressive strength (65 MPa) and flexural strength (14 MPa) for orthopaedic luting applications. In this study, two such GPC formulations, alongside two commercial cements (Simplex ® P and Hydroset™) were examined. Fracture toughness and tensile bond strength to sintered hydroxyapatite and a biomedical titanium alloy were examined. Fracture toughness of the commercial Poly(methyl methacrylate) cement, Simplex® P, (3.02 MPa m^1/2) was superior to that of the novel GPC (0.36 MPa …

Methods And Challenges Of Experimental System Identification Of A Distillation Column, Marc Christopher Moss

Masters Theses and Doctoral Dissertations

University of Tennessee at Chattanooga Engineering Department distillation column is used as a teaching tool, but is currently without a feedback control system. An eventual goal of developing such a control system requires that the behavior of the column be understood. It is necessary to identify which of the column parameters can change, either ones that change to cause a disturbance, or ones that the controller can change in response to a disturbance. There are four of these parameters in the UTC column: feed flow rate, feed composition, reboiler heat and reflux percent. Experiments were performed on the column to …

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 …

Diesel Particulate Matter Quantification And Reduction Strategies For School Buses, David Martinez-Morett

Theses and Dissertations

This thesis evaluated the contributions of school bus self pollution from both the crankcase and the tailpipe emissions to in-cabin levels of fine and ultrafine particulate matter, and determined the effectiveness of commercially available retrofit technologies towards reducing levels of particulate matter inside the school bus passenger compartment. Mobile tests were conducted with a school bus powered by an International DT466E engine on an outdoor test track. Measurements of fine and ultrafine particle concentrations within the cabin of a school bus were performed with and without retrofit technologies.

The tests utilized a drive cycle using data from actual school bus …

Electrospinning Route For The Fabrication Of P-N Junction Using Nanofiber Yarns, A. F. Lotus, S. Bhargava, E. T. Bender, E. A. Evans, R. D. Ramsier, Darrell Hyson Reneker, G. G. Chase

College of Polymer Science and Polymer Engineering

Electrospinning is a simple, versatile, and cost effective method for generating nanoscale fibers, wires, and tubes. Nanowires and nanotubes could be important building blocks for nanoscale electronics, optoelectronics, and sensors as they can function as miniaturized devices as well as electrical interconnects. We report on a simple method to fabricate free standing ceramic nanofiber heterostructures, which exhibit rectifying behavior of a p-n junction.

Comparison Of An Experimental Bone Cement With A Commercial Control, Hydroset™, O. M. Clarkin, D. Boyd, S. Madigan, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass polyalkenoate cements based on strontium calcium zinc silicate glasses (Zn-GPCs) and high molecular weight polyacrylic acids (PAA) (MW; 52,000-210,000) have been shown to exhibit mechanical properties and in vitro bioactivity suitable for arthroplasty applications. Unfortunately, these formulations exhibit working times and setting times which are too short for invasive surgical applications such as bone void filling and fracture fixation. In this study, Zn-GPCs were formulated using a low molecular weight PAA (MW; 12,700) and a modifying agent, trisodium citrate dihydrate (TSC), with the aim of improving the rheological properties of Zn-GPCs. These novel formulations were then compared with commercial …

Modelling Of Coal Slag Flow And Layer Thickness In A High Temperature Entrained Flow Gasifier, H. Katalambula

Tanzania Journal of Engineering and Technology (TJET)

A 2-D model for the slag flow simulation in an entrained flow gasifier has been developed. In addition to mass, momentum and energy conservation equations, volume of fluid (VOF) equation was solved to track the liquid-gas interface. Liquid phase consists of melted coal ash particles which deposits on the wall and move downward. The gasification reaction is not considered here but it is postulated to have a mass flow through the interface towards the mass of the liquid phase. The reactor walls are usually kept cold so a temperature gradient and then a solid layer form within the slag layer. …

Nonlinear-Optical Studies Of A Fluorinated Poled Polyimide Guest-Host System, S. F. Hubbard, K. D. Singer, F. Li, Stephen Z. D. Cheng, F. W. Harris

College of Polymer Science and Polymer Engineering

We report on poling of a low dielectric constant preimidized fluorinated fully aromatic guest-host polyimide nonlinear optical material including thermal stability of optical nonlinearities and waveguiding properties. We measured a second-harmonic coefficient (d33 = 4.9 +/- 0.5 pm/V at 1217 nm fundamental wavelength) which is accurately predicted by a thermodynamic model of poled polymers. The optical nonlinearity of a poled sample was thermally stable at 80-degrees-C for over 300 h. Films were observed to have negative birefringence. Optical losses for slab waveguides in lowest order TE and TM modes were greater-than-or-equal-to 7.7 dB/cm for doped waveguides at 800 nm wavelength …

Investigation Of Additives For Use In Electroless Plating Solutions For Fabrication Of Nanowires, Elliott J. Bird

Theses and Dissertations

This study focused on improvement of electroless plating methods by use of particular bath additives. The techniques developed here can enable us to plate very thin layers selectively on a nonconductive substrate and thus create metallized features on a nanoscale. Through the development of such bottom-up techniques this work contributes a key technology to achieving self-assembled nanocircuits. The use of additives in an electroless plating environment can modify the barriers to nucleation (or seeding) and growth. Two additives, namely 3-mercapto-1-propanesulfonic Acid (MPS) and 1,3-propanedisulfonic acid (PDS), notably increased the selectivity of electroless metallization on chemically modified surfaces, which can be …

Web Based Classes For Enhancement Of Prelaboratory Lectures, Tiffany Hesser, Michael Collura

Chemistry and Chemical Engineering Faculty Publications

The use of web classes, such as Tegrity Campus1, as a supplement to pre laboratory reading or a replacement for pre laboratory lectures could become a standard tool in laboratory education protocol. In classes with multiple lab sections and instructors, pre laboratory lectures can lack consistency and it can be difficult to gauge the students’ level of preparation. With the ever increasing exposure to technology, students generally prefer information in a digital and multimedia form, rather than textbook readings. Therefore, this method can prove to better prepare students prior to laboratory experiments, increasing the overall understanding of the chemical reactions …

Universal Scaling Behavior In Startup Shear Of Entangled Linear Polymer Melts, Pouyan E. Boukany, Shi-Qing Wang, Xiaorong Wang

College of Polymer Science and Polymer Engineering

We have studied stress overshoot behavior in startup shear of four monodisperse polymer melts with a range of chain entanglement from Z = 24 to 160 entanglement points per chain. In the elastic deformation regime defined by (gamma)over dot tau(R) > 1 where tau(R) is the Rouse relaxation time, (i) the peak shear stress sigma(max) scales with the time t(max) at the peak to -1/2 power, in contrast to an exponent of -1/4 in the viscoelastic regime (for (gamma)over dot tau(R) < 1), (ii) sigma(max) changes linearly with the elapsed strain at the stress peak gamma(max), which scales with the applied shear rate as (gamma)over dot(1/3), (iii) a supermaster curve collapses time-dependent shear stress growth curves up to the stress maximum at all shear rates for all the four styrene-butadiene rubber samples. (C) 2009 The Society of Rheology. [DOI: 10.1122/1.3086872]

Production Of Biobutanol From Biomass Using Novel Membrane Reactor, Natalie Thibodeaux

Chemical Engineering Undergraduate Honors Theses

Producing biobutanol from a waste product on a large scale is a novel idea. Because of this, there is very little research available in this area. Previous fermentation research has primarily focused on the production of ethanol or biobutanol using cellulosic or agricultural feed stocks. The Phase I research team, Team R azorbacks E ngineering FU el S olutions for E veryone (Team REFUSE), sought to design a fermentation process that would produce butanol from food waste. Team REFUSE cultivated a partnership with Chartwells, the campus food service provider for the University of Arkansas, for the acquisition of food waste. …

A Rapid Method For Flow-Ready Cylindrical Microchannel Fabrication, Kimberly H. Henthorn

Chemical and Biochemical Engineering Faculty Research & Creative Works

Most current methods of microchannel fabrication are expensive and time consuming or result in noncylindrical channels, which is undesirable for many applications. A rapid inexpensive method for the fabrication of flow-ready cylindrical polymer microchannels from polydimethylsiloxane (PDMS) is presented here. In this method, cylindrical needles are used as molds for the channels and also function as flow delivery devices after fabrication. Validation of channel function and smoothness can be accomplished by comparing experimental data to theoretical models. One model was previously developed by the author to predict the incipient motion of a glass sphere in contact with a perfectly smooth …

Experimental Investigation Of Mixing Time In A Stirred, Torispherical-Bottomed Tank Equipped With A Retreat-Blade Impeller, Nonjaros Chomcharn

Theses

Glass-lined reactors are typically used in the pharmaceutical and specialty chemicals industries because of their material compatibility with most reactants and their cleanability. These reactors are typically equipped with a retreat-blade impeller placed close to the bottom of the tank a single baffle mounted from the top. The mixing performance of such reactors has not received significant attention in the literature, despite their ubiquitous presence in the pharmaceutical industry. In particular, mixing time, i.e., the time required by the system to achieve a predefined level of homogeneity, has not been studied to any significant degree.

In this work, the mixing …

Mixing Performance Of A Novel, Continuous Confined Impinging Jets Mixer Using Competitive Reactions, Han Zheng

Theses

In this work, a novel continuous flow apparatus featuring the impingement of fluid jet streams in the presence of ultrasonic energy provided by an ultrasonic probe was tested using competitive reactions in order to determine its mixing effectiveness. The ultrasonic energy enhances micromixing of the fluid jet streams, which results in an overall mixing effectiveness improvements in different physical and chemical processes.

In the competitive reactions system used here (third Bourne reaction), one stream containing sodium hydroxide was continuously fed to the first impinging jet, while an aqueous solution of hydrochloric acid and ethyl chloroacetate was fed to the second …

Electrode Of Metallic Oxides Coated Titanium With Interlayer, Yi Tang, Li-Kun Xu, Yong-Lei Xin, Jun-Tao Wang, Ping Long

Journal of Electrochemistry

Various Ti/IrRuSn,Ti/IrTa/IrRuSn and Ti/IrTaSn/IrRuSn oxide electrodes were prepared by sol-gel method.The surface morphology and microstructure were analysed with FESEM and XRD.The electrochemical activity and stability were investigated using electrochemical technologies including chlorine and oxygen evolving potential measurements,cyclic voltammetry,accelerated life test,and alternative electrolysis.The results indicate that the electrodes with interlayers present more cracks on the surface and a little bigger average grain size,with particles of different shapes precipitated in the cracks.The electroactive sites are increased and the selectivity for the chlorine evolving reaction is enhanced,but the current efficiency for the chlorine production is somewhat lowered by the addition of different interlayers.The …

Preparation And Electrochemical Properties Of Layered Manganese Oxide(Li-Birnessite Type), Xing-Kang Huang, Hai-Tao Chang, Jian-Long Gan, Qing-Shun Zhang, Hong-Jun Yue, Dong-Ping Lv, Yong Yang

Journal of Electrochemistry

Layered Li-birnessite was prepared by means of oxidizing Mn²⁺ with O₂ gas in alkaline media.The as-prepared sample was characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), BET and thermogravimetric/diffenential thermal analysis(TG/DTA) techniques. The electrochemical properties of the material were also investigated. The results show that such a Li-birnessite consists of well-crystallized spherical particles with an interlayer distance of 0.70 nm. The Li-birnessite delivered a high discharge capacity of 203 mAh/g at a rate of 0.2 C(40 mA/g), and had good rate capability as well.