Kinetics Of Iron Research Articles

Oxidation of iron, aluminium and titanium films in the temperature range 50–200 °C

The oxidation kinetics of iron, aluminium and titanium films have been studied in the temperature range 50–200 °C at a pressure of 0.7 Pa with a piezoelectric quartz microbalance. For titanium, additional measurements in the pressure range 7 × 10 −3 – 70 Pa have been carried out. All three metals under investigation showed qualitatively common features in their oxidation behaviour: a very fast initial oxygen absorption step, completed in less than 1 min, followed by a slow, temperature-independent oxide growth with logarithmic time law at lower temperatures, and an enhancement of the oxidation rate at higher temperatures. The oxidation curves are compared with the results of model calculations based on the Cabrera-Mott theory.

Dissociation Kinetics of (N-Methylacetohydroxamato)iron(III) Complexes: A Model for Probing Electronic and Structural Effects in the Dissociation of Siderophore Complexes

Dissociation Kinetics of (N-Methylacetohydroxamato)iron(III) Complexes: A Model for Probing Electronic and Structural Effects in the Dissociation of Siderophore Complexes

Thermal decomposition kinetics of solid iron(III) tris- N- p-nitrobenzoyl- N-phenylhydroxylamine

The thermal decomposition kinetics of iron(III) tris- N- p-nitrobenzoyl- N-phenylhydroxyl-amine was studied by the isothermal heating technique in the range 164–177°C. The principal non-gaseous stable products of the thermal decomposition were isolated and identified. The thermal decomposition process seems not to obey a single kinetic model in the full range of studied temperatures. Kinetic models that should account for the experimental evidence are discussed.

Extraction kinetics of copper, zinc, iron, and manganese from contaminated sediment using Disodium Ethylenediaminetetraacetate

One technique for cleansing heavy metal contaminated soils is to wash the excavated soil with an extraction solution of a chelating agent. The rate of extraction is an important parameter when considering the length of time needed for soil clean-up and the amount and concentration of wash solution required. The extraction kinetics of copper, zinc, iron and manganese from a contaminated sediment of the Clark Fork River in western Montana, U.S.A., with Disodiun Ethylenediaminetetraacetate (Na2EDTA) as the extraction agent, were investigated. The results showed the extraction process consisted of rapid extraction in the first minutes followed by much slower extraction for the remainder of the experiment. The rate of extraction, particularly in the rapid phase, demonstrated clear pH dependence: the lower the pH, the faster the extraction rate. In the EDTA concentration range of 0.01 M to 0.05 M, the effect of the EDTA concentration on the extraction rate was not important compared with that of the solution pH. Extraction kinetics for different size particles were similar, although in the first few minutes, EDTA extracted more metals from clay and silt than sand. The two reaction, diffusion, and two-constant kinetic models were compared to experimental results. The two reaction model did not fit any of the data well, and only iron extraction could be described with a simple diffusion model. In general the extraction rates can be well described by the two-constant model, C=A t B, up to 600 minutes and under different conditions such as solution pH, EDTA concentration, and different sediment particle size.

In-situ study of high temperature corrosion kinetics of iron using a fast X-ray diffraction method

In-situ study of high temperature corrosion kinetics of iron using a fast X-ray diffraction method

Mono‐complex formation kinetics of iron(III) with nonsubstituted octane and nonane 2,4‐dicarbonyl ligands in aqueous solution

AbstractThe kinetics and mechanism of the reaction of complexation of iron(III) with 2,4‐octanedione and 2,4‐nonanedione have been investigated spectrophotometrically in aqueous solution at 10°C and ionic strength 0.5 mol dm−3 NaClO4. The equilibrium constants of the mono‐complexes have been determined. The mechanism proposed to account for the kinetic data involves a double reversible pathway where both Fe3+ and Fe(OH)2+ react with the enol tautomer of the ligand. 2,4‐Octanedione reacts with Fe3+ and Fe(OH)2+ with rate constants of 0.65 dm3 mol−1 s−1, and 14.07 dm3 mol−1 s−1, respectively. For 2,4‐nonanedione complexation the rate constants determined are 0.49 dm3 mol−1 s−1, and 11.39 dm3 mol−1 s−1, respectively. Some discussions are made on the basis of Eigen‐Wilkins theory considering the effect of solvent exchange on the complex formation. © 1993 John Wiley & Sons, Inc.

Kinetics of iron(II) oxygenation at low partial pressure of oxygen in the presence of natural organic matter

Rates of Fe(II) oxidation were measured in aqueous solutions of neutral pH, with partial pressure of oxygen (po 2 ) at 0.005, 0.02, 0.20 atm. The effects of natural organic matter (NOM), fulvic acid (FA), and polyglutamate on Fe(II) oxidation were investigated. Atpo 2 of 0.2 atm, NOM had little effect on the rate of Fe(II) oxidation. The rate exhibited first-order behavior with respect to Fe(II) concentration, and the oxidation half-time (t 1/2 ) was about 20 min. However, at low po 2 (0.005 atm), the oxidation rate showed an apparent zero-order behavior, with t 1/2 of 40 h. Organic compounds (NOM, polyglutamate, and FA) enhanced the oxidation reaction. The half time, t 1/2 , shortened to 8 h in the presence of 2.0 mg L -1 of NOM

Ferroxidase kinetics of human liver apoferritin, recombinant H-chain apoferritin, and site-directed mutants.

A detailed study of the kinetics of iron(II) oxidation by molecular oxygen in natural and recombinant human apoferritins has been carried out using electrode oximetry to better understand the ferroxidase activity of the protein shell. A comparative study of recombinant L-chain ferritin (rLF), recombinant H-chain ferritin (rHF), and variants has shown that (1) rLF lacks a ferroxidase activity, confirming the results of previous studies; (2) the ferroxidase site of rHF involves Glu-62 and His-65, presumably as Fe2+ ligands, since mutation of these residues abolishes most of the oxidase activity, in agreement with previous studies; and (3) mutation of both the putative ferroxidase and nucleation site ligands in rHF renders the protein totally incapable of catalyzing the oxidation of Fe2+ whereas mutation of nucleation site ligands alone (Glu-61, Glu-64, and Glu-67) decreases the activity only slightly. Analysis of the kinetics of rHF and natural human liver ferritin (HLF) (4% H-chain, 96% L-chain) gave the following apparent parameters at pH 7: Km,O2 = 6 +/- 2 microM, Km,Fe = 80 +/- 10 microM, and kcat = 201 +/- 14 min-1 for rHF and Km,O2 = 60 +/- 12 microM, Km,Fe = 50 +/- 10 microM, and kcat = 31.2 +/- 0.6 min-1 for HLF. Furthermore, Zn2+ was shown to be a noncompetitive inhibitor of Fe2+ oxidation in rHF but a mixed inhibitor in HLF. These different forms of Zn2+ inhibition in the two proteins and the higher activity of HLF than expected, based on its H-chain composition as well as differences in their enzyme kinetic parameters, suggest that H- and L-chains cooperate in modulating the ferroxidase activity of the apoferritin even though the L-subunit lacks a ferroxidase site itself.

Complex-formation kinetics of iron(III) with chlorite ion in aqueous solution. Mechanistic information from pressure effects

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComplex-formation kinetics of iron(III) with chlorite ion in aqueous solution. Mechanistic information from pressure effectsIstvan Fabian and Rudi van EldikCite this: Inorg. Chem. 1993, 32, 15, 3339–3342Publication Date (Print):July 1, 1993Publication History Published online1 May 2002Published inissue 1 July 1993https://doi.org/10.1021/ic00067a025RIGHTS & PERMISSIONSArticle Views63Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (540 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Numerical Simulation of the Solidification Kinetics of Cast Iron

This work proposes a model that is solved numerically to describe the solidification kinetics of castings. In particular, thermal curves and cooling rates are predicted for cast iron of hypoeutecti...

Electrodissolution Kinetics of Iron in Chloride Solutions: IX . Effect of Benzotriazole on Potential Oscillations

This study examined the effect of the organic inhibitor, benzotriazole (BTA), on the oscillatory behavior of high‐rate Fe electrodissolution in concentrated chloride media. Linear sweep experiments with rotating disk electrodes showed well‐defined limiting currents for both uninhibited and inhibited iron. In the presence of BTA, the inhibition of Fe dissolution was observed in the entire potential region examined, with the onset of the limiting diffusion current occurring at lower potentials. Galvanostatic experiments showed that potential oscillations for both uninhibited and inhibited Fe occurred at applied current densities within and above the limiting diffusion current; the potential oscillations exhibited a variety of waveforms. The chaotic oscillations were characterized by power spectral densities, phase portraits, Poincaré sections, correlation dimensions, and Lyapunov exponents. The effect of BTA on the oscillatory behavior of Fe in concentrated chloride solutions was interpreted in terms of a duplex inner nonporous layer‐outer porous salt film model.

Electrodissolution Kinetics of Iron in Chloride Solutions: VIII . Chaos in Potential/Current Oscillations

The electrodissolution of iron in aqueous solutions has been studied under a variety of conditions with rotating ring‐disk electrodes. The current oscillations observed under potentiostatic conditions, as well as the potential oscillations observed under galvanostatic conditions, are all aperiodic. Detailed analysis, using numerical diagnostics developed to characterize complex time series, clearly shows that the irregularity in these time series corresponds to deterministic chaos, rather than to random noise. The estimation of the correlation dimension in systems where the underlying dynamics are deterministic, but in which experimental noise is also present, is accomplished by a new technique described here.

Ozonation kinetics of iron and manganese in aqueous solution

AbstractOzonation kinetics of iron and manganese in aqueous solution is experimentally investigated. The effects of pH, initial ion concentration and the ozone dosage on the kinetic rate parameters are examined. It has been found that ozonation of those ions in general follows zero order kinetics.

Thermal decomposition kinetics of iron(III), cobalt(II), nickel(II) and copper(II) complexes of a Schiff base derived from quinoxaline-2-carboxaldehyde and glycine

Quinoxaline-2-carboxalideneglycine complexes of iron(III), cobalt(II), nickel(II) and copper(II) complexes were subjected to a systematic TG/DTG analysis. The decomposition process consists of two stages for all these complexes. Kinetic parameters were evaluated for each of these stages using the Coats-Redfern equation. The rate of decomposition at the second stage seems to have a bearing on the catalytic effect of the metal oxides formed during this stage.

Kinetics of iron(III) reduction by hemoglobin and its isolated .alpha.-subunits

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of iron(III) reduction by hemoglobin and its isolated .alpha.-subunitsBruce R. Van Dyke, Louis Katen, Jack Hegenauer, and Paul SaltmanCite this: Inorg. Chem. 1992, 31, 19, 4017–4018Publication Date (Print):September 1, 1992Publication History Published online1 May 2002Published inissue 1 September 1992https://doi.org/10.1021/ic00045a031RIGHTS & PERMISSIONSArticle Views44Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (248 KB) Get e-Alerts Get e-Alerts

Study by thermoelectric power and resistivity measurements of the precipitation kinetics in zirconium alloys between 450 and 600°C

Abstract Precipitation kinetics of iron, chromium or nickel, in various zirconium alloys (Zircaloys-2 and -4, Zr-Fe, Zr-O-Fe. Zr-Sn-O-Fe or Zr-Sn-O-Cr alloys), quenched from the upper limit of the α domain, are studied by thermoelectric power (TEP) and electrical resistivity measurements. A good correlation is found between the variations of these two properties due to precipitation. However, TEP measurements are more easy to perform, and are chosen as investigation technique rather than resistivity measurements. TEP increases when the amount of elements (Fe, Cr and Ni) in solid solution decreases: the corresponding influence coefficient on TEP of iron and chromium in solid solution is determined. It is shown that the solubility variation of iron and chromium between 450 and 550°C depends on the presence of oxygen. Quantitative data on the time necessary to obtain complete precipitation are given and it is shown that this time is strongly increased by the presence of oxygen and tin. Two-stage precipitation kinetics are observed in some alloys depending on the quench temperature and on the aging temperature. The existence of these two stages is however not fully understood.

Kinetics of iron(III) bromide extraction with n-tributyl phosphate

The equilibrium and rate of solvent extraction of FeBr2 complexes from HBr solutions into benzene solutions of tributyl phosphate (TBP) have been investigated. It is found that two reactions control the iron(III)-TBP extraction from hydrobromic acid solutions. From HBr activity of 1.2–1.55 (molarity based) the reaction is inverse third order with respect to the aqueous phase acidity. From HBr activity of 1.7–6 (molarity based) the reaction is first order in HBr concentration in the aqueous phase. Both of these reactions are first order for both Fe(III) and TBP. The rate constants for these reactions were calculated and the rate-controlling steps are discussed.

Effect of pressure on the complex formation and aquation kinetics of iron(III) with hydroxamic acids

Effect of pressure on the complex formation and aquation kinetics of iron(III) with hydroxamic acids

Iron(III) binding in DNA solutions: Complex formation and catalytic activity in the oxidation of hydrazine derivatives

A strong interaction between iron(III) and calf thymus DNA at pH 7.4 was demonstrated in the present study by separation of the complex by column chromatography and by the slow kinetics of iron(III) removal from DNA by disodium-1,2-dihydroxybenzene-3,5-disulfonate (Tiron). An equilibrium constant of 2.1 × 10 14 was calculated by measurements of bound iron(III) by flame atomic absorption spectroscopy and assuming a one iron to two nucleotide stoichiometry. Graphic analysis of the interaction however, indicated that DNA has two binding sites for iron(III) characterized by a stoichiometry of one iron to 12 nucleotides and one iron to 2 nucleotides, and association constants of 4.8 × 10 12 and 2.3 × 10 11, respectively. The DNA-iron(III) complex isolated by column chromatography was shown to catalyze the oxidation of both 2-phenylethylhydrazine and methylhydrazine by spin-trapping experiments with α-(4-pyridyl 1-oxide)- N-tert-butylnitrone (POBN). By contrast, oxidation of 1,2-dimethylhydrazine was not catalyzed. Catalysis of 2-phenylethylhydrazine oxidation was confirmed by oxygen consumption studies. The results suggest that iron chelated to DNA may be significant in DNA damage induced by oxidizable chemicals.

Kinetics of electrode reactions occurring on porous iron electrodes in alkaline media

The kinetics of iron and hydrogen electrode reactions occurring on porous alkaline iron electrodes have been studied with the help of steady state and transient galvanostatic polarisation. Galvanostatic transients of porous iron electrodes in the linear polarisation regime have been analysed quantitatively, accounting for the charge-transfer and ohmic components of iron electrode reactions as well as the charge-transfer component of the hydrogen evolution reaction. These data, as also the volume of hydrogen evolved during these experiments, substantiate the catalytic effects of ferrous sulphide additives.