Chemistry Commons^™

Kinetics Study And Influence Of Water-Soluble Polymer On The Electrodeposition Of Iron From A Citrate-Chloride Electrolyte On The Basis Of Fe(Iii), Vyacheslav Protsenko, Felix Danilov

Turkish Journal of Chemistry

The kinetics of the iron electrodeposition reaction from a plating bath containing trivalent iron ions is investigated in the present work. The electrochemical reaction is stated to proceed via the formation of relatively stable intermediates: Fe(II) ions. Only a part of the total amount of Fe(II) ions formed at the first stage of Fe(III) discharge is reduced further, producing metal iron. The effect of polyhexamethyleneguanidine hydrochloride (with an average molecular weight of 1000) on the iron deposition is ascertained. The presence of polymer additive in the iron electrolyte appreciably affects the rate of iron deposition, while the polymer additive does …

The Critical Role Of Water At The Gold-Titania Interface In Catalytic Co Oxidation, Johnny Saavedra, H. Doan, Christopher J. Pursell, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

We provide direct evidence of a water-mediated reaction mechanism for room-temperature CO oxidation over Au/TiO2 catalysts. A hydrogen/deuterium kinetic isotope effect of nearly 2 implicates O-H(D) bond breaking in the rate-determining step. Kinetics and in situ infrared spectroscopy experiments showed that the coverage of weakly adsorbed water on TiO2 largely determines catalyst activity by changing the number of active sites. Density functional theory calculations indicated that proton transfer at the metal-support interface facilitates O2 binding and activation; the resulting Au-OOH species readily reacts with adsorbed Au-CO, yielding Au-COOH. Au-COOH decomposition involves proton transfer to water and was suggested to be …

Kinetics Of Solid Phase Crystallization Of A-Ge Thin Films, John D. Graham

Macalester Journal of Physics and Astronomy

A method was developed to investigate the solid-phase crystallization (SPC) reaction undergone by germanium thin films. Amorphous films were grown by the radio-frequency (RF) magnetron sputtering and then annealed for a maximum of 6 hours at two temperatures: 446°C and 460°C. Crystallinity was measured by resistivity measurements, as well as crystal peak height and area taken from X-ray diffractometer (XRD) data. Initial data shows qualitative agreement with a nucleation-growth model for the observed kinetic process. However, observed peak narrowing phenomena suggests a comprehensive model of XRD measurements of polycrystalline thin films is needed for a rigorous interpretation of the results.

Kinetics Of Formation And Oxidation Of 8-Oxo-7,8-Dihydroguanine (8oxog), Derrick Ampadu Boateng

Electronic Theses and Dissertations

8-oxo-7,8-dihydroguanine (8oxoG) is one of the most important base lesions formed during oxidative damage of DNA. The aim of the present research was to investigate the effects of DNA concentration, G content, and the nature of oxidizing species on the kinetics of 8oxoG in model DNA solutions by using HPLC. The experimentally obtained yields of 8oxoG were typically in the range of 2-2.5% of total concentration of guanine. The ratios of the rate constant of hole diffusion in DNA to the rate constant of conversion of the hole into 8oxoG (k_d/k_r) were calculated from the experimental …

Analysis Of The Kinetics Of Atmospherically Important Reactions, Marie Killian Chilton, Dr. Jaron Hansen

Journal of Undergraduate Research

Organic peroxy radicals react to form tropospheric ozone, which harms the health of humans and vegetation and is considered the most significant pollutant in rural areas.1 Many of the individual reactions in the overall mechanism for ozone formation involve radicals. Radicals are highly reactive and therefore it is challenging to measure their fundamental properties directly. Particularly, it is difficult to determine an accurate reaction rate constant for reactions involving radicals. This rate constant is largely dependent on the atmospheric conditions. Dr. Jaron Hansen is currently studying the effect of water vapor on the kinetic rate constant for the reaction of …

From Micro- To Nano-Scale: Applications Of Solid-Phase Enzymatic Reactors For Biopolymer Disassembly, Nyote J. Calixte

LSU Doctoral Dissertations

The process of immobilizing enzymes onto solid supports for bioreactions has some compelling advantages compared to their solution-based counterpart including the facile separation of enzyme from products, elimination of enzyme autodigestion, and increased enzyme stability and activity. We report in this work, the immobilization of λ-exonuclease onto poly(methylmethacrylate) (PMMA) micro- and nano-pillars populated within a fluidic devices for the micro and nanoscale on-chip digestion of double-stranded DNA. Enzyme immobilization in both studies was successfully accomplished using 3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling to carboxylic acid functionalized PMMA micropillars. Our micro-scale results suggest that the reaction efficiency for the catalysis of dsDNA digestion …

The Curing And Degradation Kinetics Of Epdm Rubber, Robert J. Wehrle

Browse all Theses and Dissertations

Ethylene-propylene-diene (EPDM) rubbers containing varying amounts of diene were cured with sulfur using either a moving die rheometer (MDR) or a rubber process analyzer (RPA). The effect of removing curatives and how the curing reaction changed was explored. Kinetic data was extracted from the rheology plots and reaction rate constants were determined by two separate ways: manually choosing points of interest or by a computer model.

Synthesis, Characterization And Application Of Two-Dimensional Layered Metal Hydroxides For Environmental Remediation Purposes, Cleopas Machingauta

Dissertations (1934 -)

Two-dimensional layered nano composites, which include layered double hydroxides (LDHs), hydroxy double salts (HDSs) and layered hydroxide salts (LHSs) are able to intercalate different molecular species within their gallery space. These materials have a tunable structural composition which has made them applicable as fire retardants, adsorbents, catalysts, catalyst support materials, and ion exchangers. Thermal treatment of these materials results in destruction of the layers and formation of mixed metal oxides (MMOs) and spinels. MMOs have the ability to adsorb anions from solution and may also regenerate layered structures through a phenomenon known as “memory effect”. Zinc-nickel hydroxy nitrate was used …

Identification Of An Active Site-Bound Nitrile Hydratase Intermediate Through Single Turnover Stopped-Flow Spectroscopy, Natalie Gumataotao, Misty L. Kuhn, Natalia Hajnas, Richard C. Holz

Chemistry Faculty Research and Publications

Stopped-flow kinetic data were obtained for the iron-type nitrile hydratase from Rhodococcus equi TG328-2 (ReNHase) using methacrylonitrile as the substrate. Multiple turnover experiments suggest a three-step kinetic model that allows for the reversible binding of substrate, the presence of an intermediate, and the formation of product. Microscopic rate constants determined from these data are in good agreement with steady state data confirming that the stopped-flow method used was appropriate for the reaction. Single turnover stopped-flow experiments were used to identify catalytic intermediates. These data were globally fit confirming a three-step kinetic model. Independent absorption spectra acquired between 0.005 …

Properties And Structures Of Li-N Based Hydrogen Storage Materials, Junqing Zhang

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

Traditional transportation fuel, petroleum, is limited and nonrenewable, and it also causes pollutions. Hydrogen is considered one of the best alternative fuels for transportation. The key issue for using hydrogen as fuel for transportation is hydrogen storage. Lithium nitride (Li3N) is an important material which can be used for hydrogen storage. The decompositions of lithium amide (LiNH2) and lithium imide (Li2NH) are important steps for hydrogen storage in Li3N. The effect of anions (e.g. Cl-) on the decomposition of LiNH2 has never been studied. Li3N can react with LiBr to form lithium nitride bromide Li13N4Br which has been proposed as …

Molecular Products From The Thermal Degradation Of Selected Tobacco Components: Lignin, Tyrosine, Glutamic Acid, And Modeling Of Lignin Pyrolysis Using Chemkin Combustion Suite, Joshua Kiprotich Kibet

LSU Doctoral Dissertations

This study explores the thermal decomposition behavior of selected tobacco components: lignin, tyrosine, and glutamic acid using the system for thermal diagnostic studies (STDS) in an in-line gas chromatography-mass spectrometer analytical technique. The pyrolysis conditions employed in this study were a flowing atmosphere of nitrogen and 4% O2 in nitrogen at a residence time of 0.2 seconds for a total pyrolysis time of 3 minutes. The results identified common relationships between the two modes of reaction atmospheres, as well as some differences. While some products were favored by an inert regime, some were favored under an oxidative regime. Oxidative pyrolysis …

Application Of Glycyrrhiza Glabra Root As A Novel Adsorbent In The Removal Of Toluene Vapors: Equilibrium, Kinetic, And Thermodynamic Study, Fazel Mohammadi-Moghadam, Mohammad Mehdi Amin,, Mehdi Khiadani, Fariborz Momenbeik, Heshmatollah Nourmoradi, Mohammad Sadegh Hatamipour

Research outputs 2013

The aim of this paper is to investigate the removal of toluene from gaseous solution through Glycyrrhiza glabra root (GGR) as a waste material. The batch adsorption experiments were conducted at various conditions including contact time, adsorbate concentration, humidity, and temperature. The adsorption capacity was increased by raising the sorbent humidity up to 50 percent. The adsorption of toluene was also increased over contact time by 12 h when the sorbent was saturated. The pseudo-second-order kinetic model and Freundlich model fitted the adsorption data better than other kinetic and isotherm models, respectively. The Dubinin-Radushkevich (D-R) isotherm also showed that the …

Removal Of Heavy Metals Using Modified Limestone Media: Zinc And Cadmium, Keerthy Mandadi

Masters Theses & Specialist Projects

Heavy metal contamination is a serious concern throughout the world. Increased concentrations in drinking water have many negative impacts on human health. Limestone is an inexpensive and simple media for removing high concentrations of heavy metals from drinking water supplies. Ferric based media is commonly used to remove zinc, cadmium, lead, arsenic and other heavy metals. The drinking water standards set by the US EPA for cadmium, zinc and arsenic are 0.005 mg/L, 5 mg/L and 0.010 mg/L respectively. Bangladesh, parts of India, China and the United States have high concentrations of arsenic in drinking water. Although many technologies exist …

Nmr Characterization Of Parathion: Properties, Transport, And Reaction Kinetics, Emma Catherine Baker

Boise State University Theses and Dissertations

The hydrolysis reaction of parathion (PTH) to produce para-nitrophenolate (pNP) and O,O-diethylthiophosphate (DETP) was examined in a minimally disturbed liquid-liquid biphasic reaction system by proton and phosphorous nuclear magnetic resonance spectroscopy. The effect of the micellar cationic surfactant, cetyltrimethylammonium chloride (CTAC), on PTH transport, hydrolysis, and system characteristics including reactant-product concentrations, pNP partition coefficients, pNP surface activity, ultraviolet degradation of pNP, oxidation of pNP, and impurities in PTH are reported. Surfactant reaction systems resulted in a 2.5 order of magnitude increase in the amount of PTH transported into the aqueous layer as compared to the control system at 2100 …

The Kinetics And Mechanisms Of Some Fundamental Organic Reactions Of Nitro Compounds, Zhao Li

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In chemistry, kinetics is the study of the rates of chemical reactions. A reaction mechanism describes in detail exactly what takes place at each stage of an overall chemical reaction from reactants to products. The work outlined in this dissertation was carried out in order to find out the true mechanisms of some fundamental organic reactions of nitro compounds by means of a series of novel kinetic techniques and analysis methods.

The target reactions include (1) the proton transfer reactions of nitroalkanes and (2) the aromatic nucleophilic reactions of trinitroarenes, both of which are undeniably among the most elementary and …

Transient Ru-Methyl Formate Intermediates Generated With Bifunctional Transfer Hydrogenation Catalysts, Richard H. Perry, Kristen R. Brownell, Konstantin Chingin, Thomas J. Cahill Iii, Robert M. Waymouth, Richard N. Zare

Chemistry and Physics Faculty Articles

Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (β-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH₃OH). By placing [(p-cymene)RuCl₂]₂ on a surface and spraying a solution of β-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH₃). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that …

Dynamics Of The Solvent Exchange Reaction Of Weakly Bound Organic Solvents To Group 6 Transition Metal Carbonyls And The Molybdenum Hexacarbonyl Mediated Pauson-Khand Reaction, Richard J. Gates

Theses and Dissertations

Many organometallic reactions are solvent-dependent, suggesting solvent molecules interact with reaction intermediates. Studies of the solvent exchange reaction of group 6 transition metal carbonyls with moderately binding ligands have provided insight into these interactions, however, studies of the mechanism for this reaction with weakly binding ligands have not been performed. Experiments were conducted on the nanosecond time scale in methylcyclohexane over the temperature range of 4 to 44 °C using Step Scan FTIR (SS FTIR) spectroscopy with weakly binding ligands benzene and mesitylene. Upon photolysis of the metal hexacarbonyls, the kinetically favored product (M(CO)5(solv)), decays following pseudo-first-order kinetics to the …

Kinetic Studies On Lactonization Of Quinone Propionic Acid Derivatives For The Development Of Redox Responsive Liposomes, K. L. Iresha Sampathi Perera

LSU Master's Theses

ABSTRACT Stimuli-responsive liposome systems that utilize endogenous triggers of tumor microenvironment have generated great attention in recent drug delivery research. Among such formulations, redox-responsive liposomes seem highly promising for cancer treatment due to their potential to release high drug concentrations upon reduction (by reductase enzymes). The research described in this thesis involved the evaluation of kinetics of trimethyl-lock quinone propionic acid reduction and lactonization, which accounts for payload release from trimethyl-lock quinone propionic acid-decorated liposomes. To achieve the ultimate goal of this research, several trimethyl-lock quinone propionic acid-based amide compounds were synthesized and characterized. Kinetic studies were carried out with …

Nmr Line Shapes And Multi-State Binding Equilibria, Evgenii L. Kovrigin

Chemistry Faculty Research and Publications

Biological function of proteins relies on conformational transitions and binding of specific ligands. Protein-ligand interactions are thermodynamically and kinetically coupled to conformational changes in protein structures as conceptualized by the models of pre-existing equilibria and induced fit. NMR spectroscopy is particularly sensitive to complex ligand-binding modes—NMR line-shape analysis can provide for thermodynamic and kinetic constants of ligand-binding equilibria with the site-specific resolution. However, broad use of line shape analysis is hampered by complexity of NMR line shapes in multi-state systems. To facilitate interpretation of such spectral patterns, I computationally explored systems where isomerization or dimerization of a protein (receptor) molecule …

Atr-Ftir Studies On The Kinetics Of Dimethylarsinic Acid (Dma) Surface Complexation With Iron(Oxyhydr)Oxides, Julia Tofan-Lazar Miss

Theses and Dissertations (Comprehensive)

Dimethylarsinic acid (DMA) is an organoarsenical compound that, along with monomethylarsonic acid, poses a health and an environmental risk, and a challenge to the energy industry. Little is known about the surface chemistry of DMA at the molecular level with materials relevant to geochemical environments and industrial sectors. The surface chemistry of phosphorus and arsenic compounds in their organic and inorganic forms is of great interest due to its role in controlling their transport, bioaccessibility and speciation. This thesis reports the first in-situ and surface-sensitive rapid kinetic studies on the adsorption and desorption of DMA to and from Fe-(oxyhydr)oxide films …

Section Abstracts: Chemistry

Virginia Journal of Science

Abstracts of the Chemistry Section for the 89th Annual Meeting of the Virginia Academy of Science, May 25-27, 2011, University of Richmond, Richmond VA.

Formation And Stability Of Atmospherically Relevant Isoprene-Derived Organosulfates And Organonitrates, Adam I. Darer, Neil C. Cole-Filipiak, Alison E. O'Connor, Matthew J. Elrod

Faculty & Staff Scholarship

Isoprene is the precursor for number of alcohol, organosulfate, and organonitrate species observed in ambient secondary organic aerosol (SOA). Recent laboratory and field work has suggested that isoprene-derived epoxides may be crucial intermediates that can explain the existence of these compounds in SOA. To confirm this hypothesis, the specific hydroxy epoxides observed in gas phase isoprene photooxidation experiments (as well as several other related species) were synthesized and the bulk phase aqueous reactions of these species in the presence of sulfate and nitrate were studied via nuclear magnetic resonance (NMR) techniques. The results indicate that both primary and tertiary organosulfates …

Detection Of Quercetin Using Polymer Coated Quartz Crystal Microbalance And The Modification Of Á-Zirconium Phosphate To Develop A Sorbent For Organic Pollutant Removal, Darlington Mlambo

Dissertations (1934 -)

Sorption processes involve physical and chemical interactions of sorbents with analytes. These may involve the physical and/or chemical processes in which a substance is accumulated at an interface between two phases, or the intermixing of a substance with the matrix of a second phase. The two processes are referred to as adsorption and absorption respectively. The sorption capacities of different classes of sorbents have many potential and demonstrated applications such as sensor development, water treatment, environmental remediation and chromatographic separations. The goal of this work is to explore the sorption capacity of polymers as well as nanodimensional layered materials for …

Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson

Chemistry Faculty Research

New bimetallic Ni-Au supported nanoparticle catalysts were prepared by using dendrimer templated nanoparticles. Amine-terminated generation 5 polyamidoamine (PAMAM) dendrimers were anchored to a commercial silica with a siloxane linked anhydride. The dendrimer was then alkylated and used to template Ni-Au nanoparticles, which were subsequently extracted into organic solution as thiol monolayer protected clusters (MPCs). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) indicated bimetallic nanoparticles of about 2 nm in size. Nanoparticles were deposited onto P-25 TiO2, and the capping thiol ligands were removed under flowing H2. DRIFTS infrared spectra of adsorbed CO showed only Au on the catalyst …

Methyl Septanoside Hydrolysis As A Measure Of Carbohydrate Ring Flexibility: Substrate Synthesis And Kinetics Analysis, Shawn Michael Miller

Honors Scholar Theses

A number of seven-membered ring systems have been found to have promising enzyme inhibiting properties. The common explanation for their efficacy is the apparent improved flexibility that the ring-system has over smaller rings. In an attempt to probe the validity of this hypothesis, unnatural seven-membered ring carbohydrates have been generated and subjected to kinetics analysis using hydrolysis. In particular, methyl α- and β-D-glycero-D-guloseptanoside were subjected to acid-catalyzed hydrolysis and monitored via HNMR experiments. The rate constants of the reactions were determined and compared to the hydrolysis rate constants of comparable pyranose carbohydrates and found to be significantly faster, indicating an …

Computational Study Of Pristine And Titanium-Doped Sodium Alanates For Hydrogen Storage Applications, Gopi Krishna Phani Dathar

Doctoral Dissertations

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained …

Kinetics Of Co Oxidation Over Pt-Ceo_X Supported On Air-Oxidized Activated Carbon, Berri̇n Gülyüz, Şeyma Özkara Aydinoğlu, Ahmet Erhan Aksoylu, Zeynep İlsen Önsan

Turkish Journal of Chemistry

Kinetics of low-temperature CO oxidation was studied under atmospheric pressure at 383 K in the initial rates region over 1wt%Pt-1wt%CeO_x supported on air-oxidized activated carbon (AC2). Feed concentrations of 1-5 mol% CO and 1-2.5 mol% O_2 with balance He were used for CO oxidation in the absence of hydrogen. A simple power-function rate expression was obtained with reaction orders of -0.24 in CO and 0.98 in O_2, and a plausible LHHW expression compatible with mechanisms reported in the literature was proposed. Feed concentrations of 5 mol% CO and 2.5 mol% O_2 were used for investigating the effect of the presence …

Patterning High Surface Area Silica With Lysozyme: Adsorption Kinetics, Fluorescence Quenching, And Protein Readsorption Studies To Evaluate The Templated Surface, Rachel M. Greer, Brittni A. Scruggs, R Alan May, Bert D. Chandler

Chemistry Faculty Research

A method was developed for using an inexpensive and widely available protein, hen egg white lysozyme, as a patterning agent for commercial high surface area silicas. The basic patterning methodology involved spontaneous adsorption of the protein from aqueous solution, alkylation of the uncovered surface with an alkylsiloxane, and protein desorption in a slightly alkaline solution of morpholine. Adsorption kinetic studies using Bradford assays assisted in determining protein deposition conditions. These studies were generally consistent with results on more planar silica surfaces and indicated that the protein quickly and strongly adsorbs along its long axis at low surface coverages. A modified …

Analyzing The Catalytic Role Of Asp97 In The Methionine Aminopeptidase From Escherichia Coli, Sanghamitra Mitra, Kathleen M. Job, Lu Meng, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

An active site aspartate residue, Asp97, in the methionine aminopeptidase (MetAPs) from Escherichia coli (EcMetAP-I) was mutated to alanine, glutamate, and asparagine. Asp97 is the lone carboxylate residue bound to the crystallographically determined second metal-binding site in EcMetAP-I. These mutant EcMetAP-I enzymes have been kinetically and spectroscopically characterized. Inductively coupled plasma–atomic emission spectroscopy analysis revealed that 1.0 ± 0.1 equivalents of cobalt were associated with each of the Asp97-mutated EcMetAP-Is. The effect on activity after altering Asp97 to alanine, glutamate or asparagine is, in general, due to a ∼ 9000-fold decrease in k_ca towards …

Synthesis Of The Lifepo4 By Co Reduction: Reaction Mechanism And Kinetics, Yun-Hua Chen, Yong Yang

Journal of Electrochemistry

LiFePO₄ cathode material was synthesized by CO reducing FePO₄ and LiOH precursors.The structure,morphology and electrochemical performances of such LiFePO₄ material were characterized by XRD,SEM and charge-discharge tests.It was shown that the particle size of the LiFePO₄ synthesized with 5% excess of LiOH in the precursor was about 200 nm.By carbon coating,the LiFePO₄ electrode was able to deliver a reversible capacity of 158 mAh·g^-1 at 0.1C discharge rate.Temperature-programmed X-ray diffraction was employed to monitor the reaction during the formation of LiFePO₄,and Li₃Fe₂(PO₄)₃ was found to be …