The anodic oxidation of ethylxanthate on metal and galena electrodes

The products of the electrochemical oxidation of potassium ethylxanthate have been identified by infrared analysis and microanalysis for the constituent elements. The current efficiency for the formation of diethyl dixanthogen depends on the nature of the electrode, and at 0.5 V was found to be 100, 98, 90, c. 50, and 0% for platinum, gold, copper, galena, and lead respectively. The remainder of the current passed at this potential resulted in the formation of the metal xanthate.� Dixanthogen is formed on lead electrodes only at potentials of > 1.0 V, where lead xanthate is unstable with respect to oxides of the metal. The lead xanthate produced on a galena electrode at pH 9.1 involves the release of thiosulphate ions. The formation of lead xanthate by this reaction, followed by its reduction to lead, is shown to change the surface characteristics of a galena electrode to those of lead. However, the formation and reduction of the initial layers which takes place on cycling the electrode potential does not change a galena surface and cannot involve loss of sulphur from the surface to the solution. This supports the conclusion that the chemisorbed xanthate monolayer is first covered by dixanthogen and that lead xanthate forms only when bulk layers are produced.

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Electrochemical investigation of contact angle and of flotation in the presence of alkylxanthates. II. Galena and pyrite surfaces

Australian Journal of Chemistry ◽

10.1071/ch9770981 ◽

1977 ◽

Vol 30 (5) ◽

pp. 981 ◽

Cited By ~ 56

Author(s):

JR Gardner ◽

R Woods

Keyword(s):

Contact Angle ◽

Electrode Potential ◽

Electrochemical Investigation ◽

Pyrite Surface ◽

Mineral Surface ◽

Hydrated Iron Oxide ◽

Mineral Particles ◽

Lead Electrode ◽

Nitrogen Bubble ◽

Metal Xanthate

The contact angle between a nitrogen bubble and galena and pyrite surfaces immersed in methyl-, ethyl- or butyl-xanthates has been determined as a function of the electrode potential and of the quantity of xanthate species formed by interaction with the mineral surface. For galena, the initial chemisorbed xanthate layer was found to be hydrophobic when ethyl- or butyl-xanthates were employed, but hydrophilic for the methyl homologue. The presence of dixanthogen enhanced the contact angle but the metal xanthate diminished it. This conclusion was supported by contact angle studies at a lead electrode. For pyrite the surface was hydrophilic except when dixanthogen was formed, but a significant quantity was required on the mineral surface before a finite contact angle was observed. This behaviour is interpreted in terms of the presence of hydrated iron oxide on the pyrite surface. �� The potentials at which particulate bed electrodes of galena and pyrite begin to float were determined for ethyl- and butyl- xanthates. The potentials correspond to the regions where chemisorption of xanthate takes place on galena and where significant quantities of dixanthogen are formed on pyrite. �� With butylxanthate, flotation was inhibited when excessive quantities of xanthate species were present on galena or pyrite. The inhibition arose from flocculation of the mineral particles.

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Influence of lead dioxide electrodes morphology on kinetics and current efficiency of oxygen-ozone evolution reactions

Chemical Papers ◽

10.2478/s11696-010-0062-2 ◽

2010 ◽

Vol 64 (6) ◽

Cited By ~ 8

Author(s):

Élen Rufino ◽

Mario Santana ◽

Luiz Faria ◽

Leonardo Silva

Keyword(s):

Current Efficiency ◽

Lead Dioxide ◽

Water Discharge ◽

Water Electrolysis ◽

Surface Characteristics ◽

Ozone Production ◽

Sem Images ◽

Pbo2 Electrode ◽

Tafel Slopes ◽

Experimental Findings

AbstractInfluence of electrode morphology on electrochemical properties of lead dioxide electrodes (β-PbO2) for oxygen-ozone evolution reactions in acid medium was investigated using scanning electronic microscopy (SEM), cyclic voltammetry (CV), polarization curves (PC), and determination of the current efficiency (Φ). Experimental findings revealed that application of high electrodeposition current densities furnishes more rough β-PbO2 films. Surface characteristics were verified by SEM images and the analysis of interfacial pseudo-capacitances and morphology factor (φ). Kinetic study of the overall electrode process (O2 + O3) based on the analysis of the Tafel slope revealed that the electrode morphology and electrolyte composition considerably affect the electrode kinetics. In most cases, the existence of two Tafel slopes distributed in the low and high overpotential domains was observed. Abnormal Tafel slopes (b ≠ 120 mV) obtained for the primary water discharge step during water electrolysis were interpreted considering the apparent charge transfer coefficient (α apa). Optimum conditions for the ozone production were obtained for the less rough β-PbO2 electrode immersed in a sulfuric acid solution (1.0 mol dm−3) containing KPF6 (30 × 10−3 mol dm−3), where the current efficiency of 15 mass % for the ozone production was obtained.

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Contribution of electrolysis current to growth of SrTiO3 thin film by the hydrothermal-electrochemical method

Journal of Materials Research ◽

10.1557/jmr.1994.2109 ◽

1994 ◽

Vol 9 (8) ◽

pp. 2109-2117 ◽

Cited By ~ 27

Author(s):

Koji Kajiyoshi ◽

Kunisaburo Tomono ◽

Yukio Hamaji ◽

Toru Kasanami ◽

Masahiro Yoshimura

Keyword(s):

Thin Film ◽

Thin Films ◽

Current Efficiency ◽

Electrode Potential ◽

Electrochemical Method ◽

Film Growth ◽

Reaction Model ◽

Total Current ◽

Anodic Current ◽

Hydrothermal Electrochemical Method

The electrolysis treatment of the hydrothermal-electrochemical method has been modified so that it permits SrTiO3 thin films to be grown on Ti electrodes being oxidized anodically in Sr(OH)2 solutions far beyond a thickness limit of several tens of nanometers hitherto attained. The relation between the total current passed through the Ti anode and the amount of the resulting SrTiO3 film was analyzed on the basis of a reaction model that interprets the anodic current to be compensated with electrons generated partly by oxidation of Ti and partly by decomposition of H2O. Current efficiency for the film growth was estimated to be in the range from 0.8 to 3% depending on the Ti electrode potential.

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Electrode potential of hydrogenated Ni-wires and foils

Journal de Chimie Physique ◽

10.1051/jcp/1981780373 ◽

1981 ◽

Vol 78 ◽

pp. 373-375

Author(s):

Amar Nath Nigam ◽

Ratna Rani

Keyword(s):

Electrode Potential

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On the Preparation of Bovine α-Thrombin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646669 ◽

1978 ◽

Vol 39 (01) ◽

pp. 193-200 ◽

Cited By ~ 7

Author(s):

Erwin F Workman ◽

Roger L Lundblad

Keyword(s):

Immobilized Enzyme ◽

Catalytic Properties ◽

Specific Activity ◽

Guanidine Hydrochloride ◽

Low Molecular Weight ◽

Reversible Process ◽

Gel Beads ◽

Tissue Thromboplastin ◽

C 50 ◽

Hydrolysis Of

SummaryAn improved method for the preparation of bovine α-thrombin is described. The procedure involves the activation of partially purified prothrombin with tissue thromboplastin followed by chromatography on Sulfopropyl-Sephadex C-50. The purified enzyme is homogeneous on polyacrylamide discontinuous gel electrophoresis and has a specific activity toward fibrinogen of 2,200–2,700 N.I.H. U/mg. Its stability on storage in liquid media is dependent on both ionic strenght and temperature. Increasing ionic strength and decreasing temperature result in optimal stability. The denaturation of α-thrombin by guanidine hydrochloride was found to be a partially reversible process with the renatured species possessing properties similar to “aged” thrombin. In addition, the catalytic properties of a-thrombin covalently attached to agarose gel beads were also examined. The activity of the immobilized enzyme toward fibrinogen was affected to a much greater extent than was the hydrolysis of low molecular weight, synthetic substrates.

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Plasminogen-Activator in Human Early Milk: Its Partial Purification and Characterization

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650147 ◽

1981 ◽

Vol 45 (02) ◽

pp. 121-126 ◽

Cited By ~ 23

Author(s):

Utako Okamoto ◽

Noboru Horie ◽

Yoko Nagamatsu ◽

Jun-Ichiro Yamamoto

Keyword(s):

Plasminogen Activator ◽

Polyacrylamide Gel Electrophoresis ◽

Gel Filtration ◽

Partial Purification ◽

Order Kinetic ◽

Diisopropyl Fluorophosphate ◽

Step Procedure ◽

Activity Band ◽

C 50 ◽

Gel Isoelectric Focusing

SummaryMilk plasminogen-activator was partially purified from human transitional milk collected at about 10 days after delivery, by a five-step procedure involving chloroform treatment, ammonium sulfate precipitation, and column chromatography on Sephadex G-150, CM Sephadex C-50 and DEAE Sephadex A-50. This gave milk-activator with a maximum purification factor of about 2,400-fold with respect to the skimmed milk. The CM Sephadex-step preparation showed, on polyacrylamide gel electrophoresis, a single plasminogen-activator activity band located between the bands of albumin and prealbumin of human serum. This preparation exhibited no kinin forming activity. The activator hydrolyzed acetyl-glycyl-L-lysine methyl ester with similar order kinetic constants to urokinase, and was inhibited strongly by diisopropyl-fluorophosphate. The molecular weight of the activator as estimated by gel filtration was approximately 86,000, the isoelectric points as estimated by gel isoelectric focusing were pH 7.2, 6.9 and 6.6, and the activator activity was not quenched by antiurokinase globulin, indicating that the milk-activator is a different entity from urokinase.

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Medial Smooth Muscle Cell Proliferation in the Balloon Injured Rabbit Aorta: Effect of a Thiazole Compound with Platelet Inhibitory Activity

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661024 ◽

1984 ◽

Vol 51 (01) ◽

pp. 075-078 ◽

Cited By ~ 8

Author(s):

R G Schaub ◽

C A Simmons

Keyword(s):

Smooth Muscle ◽

Platelet Aggregation ◽

Balloon Catheter ◽

Rabbit Aorta ◽

Surface Characteristics ◽

Inhibitory Effect ◽

Lesion Size ◽

Blue Staining ◽

Morphologic Characteristics ◽

Time Period

SummaryTwenty-seven adult male New Zealand rabbits (3–4 kgs) were used in this study. Six rabbits received vehicle, 3 groups of 6 each received doses of 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)- thiazole, (U-53,059), at 0.3 mg/kg, 3.0 mg/kg and 30.0 mg/kg/day respectively. Drug and vehicle doses were given orally each day starting 3 days before balloon injury and continuing for the entire 2 week time period. Three rabbits were used as nontreated sham controls. In the vehicle and U-53,059 treated groups aortae were denuded of endothelial cells by balloon catheter injury. Two weeks after injury platelet aggregation to collagen was measured and the aortae removed for analysis of surface characteristics by scanning electron microscopy and lesion size by morphometry. All doses of U-53,059 inhibited platelet aggregation. The 3.0 and 30.0 mg/kg groups had the greatest inhibitory effect. All balloon injured aortae had the same morphologic characteristics. All vessels had similar extent and intensity of Evan’s blue staining, similar areas of leukocyte/platelet adhesion, and a myointimal cell cover of transformed smooth muscle cells. The myointimal proliferative response was not inhibited at any of the drug doses studied.

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The innovative space as the most important element of theregional socio-economic space

Problems of Innovation and Investment Development ◽

10.33813/2224-1213.20.2019.6 ◽

2019 ◽

pp. 60-70

Author(s):

Larysa Gromozdova ◽

Inna Stenicheva

Keyword(s):

Basic Element ◽

Information Support ◽

Space Region ◽

Regional Innovation ◽

Economic Space ◽

Mechanisms Of Formation ◽

Innovation Space ◽

Space Mechanisms ◽

Constituent Elements

Purpose of the article: to determine the essence of different elements ofsocio-economic space of the region. Construction of the structure and isolationof individual elements of socio-economic space as a multi-vector formation.This article highlights the essence and different approaches to defining theconcepts, structure and mechanisms of formation of economic and social spacesof the region, innovation space as a basic element of socio-economic space.Research Methods: The methodological basis of the research is the fundamentalprinciples of economic theory, regional economy, scientific views and approachesof foreign and domestic scientists. To achieve the purpose of the study, themethods used at the empirical and theoretical levels were used: axiomatic,abstract, system-structural analysis, analogies and comparisons, graphoanalytic,by which the characterization of the nature of the concepts of space, socioeconomic space, as well as innovation space region. Their general properties,structure and functions are described.The criteria of optimality and balancesof interests in the formation of different types of space in the region areconsidered. The classification of the regional space is proposed, and the networkconnections of the innovation space according to components and elements arerevealed, which allows to study deeply the social, economic and other problemsof development of the region.Scientific novelty: the classification of regionalspace by separate constituent elements is proposed. The concept of “innovationspace” was introduced into scientific circulation, the scheme of networkconnections of the innovation space with other elements of the regional socioeconomic space was developed. Conclusions and Prospects for Further Research:In today’s context, it is possible to significantly improve the economic stateof development of Ukrainian regions by using a scientifically sound andcomprehensive approach to defining and studying the concepts of socioeconomic and innovative space.In the further study it is necessary to considerin detail the mechanism of organizational activity of innovation space in theregion. It is very important to pay attention to information support for theformation of the innovation space, the creation of a regional legal field ofinnovation space, mechanisms for coordinating regional innovation activitieswithin the innovation space, as well as the influence of internal and externalfactors on the formation and development of the innovation space.

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Photocatalytic activity of TiO2 synthesized by anodization and anodic spark deposition

MRS Advances ◽

10.1557/adv.2020.405 ◽

2020 ◽

Vol 5 (61) ◽

pp. 3141-3152

Author(s):

Alma C. Chávez-Mejía ◽

Génesis Villegas-Suárez ◽

Paloma I. Zaragoza-Sánchez ◽

Rafael Magaña-López ◽

Julio C. Morales-Mejía ◽

...

Keyword(s):

Electron Microscopy ◽

Photocatalytic Activity ◽

Surface Characteristics ◽

Amorphous Solids ◽

X Ray Diffraction ◽

X Ray ◽

Catalytic Activities ◽

Anodic Spark Oxidation ◽

Porous Surfaces ◽

Scanning Electron

AbstractSeveral photocatalysts, based on titanium dioxide, were synthesized by spark anodization techniques and anodic spark oxidation. Photocatalytic activity was determined by methylene blue oxidation and the catalytic activities of the catalysts were evaluated after 70 hours of reaction. Scanning Electron Microscopy and X Ray Diffraction analysis were used to characterize the catalysts. The photocatalyst prepared with a solution of sulfuric acid and 100 V presented the best performance in terms of oxidation of the dye (62%). The electric potential during the synthesis (10 V, low potential; 100 V, high potential) affected the surface characteristics: under low potential, catalyst presented smooth and homogeneous surfaces with spots (high TiO2 concentration) of amorphous solids; under low potential, catalyst presented porous surfaces with crystalline solids homogeneously distributed.

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