Lead Dioxide Anode Research Articles

Heterogeneous redox catalysis with lead dioxide anodes

PbO 2 anodes were used to oxidize cyclohexanone oxime to nitroso compounds in 1 M H 2SO 4 or 1 M HClO 4 in a two electron reaction: ▪ Nu − are nucleophiles like OH −, NO − 2 and Cl −. The electrode material reacts chemically with the oxime and it is oxidized electrochemically at potentials very close to the Pb 2+ 4+ redox potential. The chemical step has been studied separately by corrosion experiments in aqueous HClO 4. An upper limit of current density is observed, independent of convection, due to the formation of a film composed of Pb(II) products on the electrode. A reaction limitation was not attained under our conditions. Contrary to this, the PbO 2 electrode behaves inertly in the case of lower aliphatic alcohols (C 2C 4) in 1 M H 2SO 4. Potentials are about 0.5 V more positive. The inert anode generates the radical cation in the rate determining step: ▪ Corrosion experiments disclose a rate, which is lower by four orders of magnitude ( j corr=2–3 μA cm −2) with reference to the oxime experiment and only slightly above the corrosion rate in pure 1 M HClO 4.

ELECTROCHEMICAL ENANTIOMER-DIFFERENTIATING OXIDATION OF A RACEMIC ALCOHOL ON POLY(l-VALINE)-COATED ELECTRODES

Abstract It was found that the enantiomer-differentiating oxidation of racemic 2,2-dimethyl-1-phenyl-1-propanol (1) to the corresponding ketone (2) occurred on poly(l-valine)-coated electrodes. This reaction seemed to be the first example of electrochemical enantiomer-differentiating reaction and to be available for kinetic optical resolution: 43% optically-pure S-(−)-1 was recovered as an unreacted part, when a half amount of starting 1 was converted using a lead dioxide anode coated doubly with polypyrrole and poly(l-valine).

Potentials of New Forms of Lead Dioxide Anodes in the Electrolysis of Aqueous Sodium Chloride

Potentials of New Forms of Lead Dioxide Anodes in the Electrolysis of Aqueous Sodium Chloride

Die Reduktion von Bleidioxid-Synthese-Anoden / Reduction of Lead Dioxide Synthesis Anodes

Abstract The electrochemical and chemical reduction of α-and β-lead dioxide synthesis anodes in sulfuric or nitric acid, resp., are investigated. The processes are elucidated by scanning electron microscope pictures. For the reduction of lead dioxide to lead sulfate a solution-precipitation mechanism is confirmed. This result fits very well with present day battery research. Reduction as well as re-oxidation result in an enlargement of active surface. Therefore temporary reduction has a decisive influence on the potential characteristics of lead dioxide anodes. Conclusions are given for their application in electrochemical syntheses.

ChemInform Abstract: THE MECHANISM OF THE DISINTEGRATION OF LEAD DIOXIDE ANODES UNDER CONDITIONS OF OZONE EVOLUTION IN STRONG ACID ELECTROLYTES

Chemischer InformationsdienstVolume 13, Issue 27 Physical Inorganic Chemistry ChemInform Abstract: THE MECHANISM OF THE DISINTEGRATION OF LEAD DIOXIDE ANODES UNDER CONDITIONS OF OZONE EVOLUTION IN STRONG ACID ELECTROLYTES P. C. FOLLER, P. C. FOLLERSearch for more papers by this authorC. W. TOBIAS, C. W. TOBIASSearch for more papers by this author P. C. FOLLER, P. C. FOLLERSearch for more papers by this authorC. W. TOBIAS, C. W. TOBIASSearch for more papers by this author First published: July 6, 1982 https://doi.org/10.1002/chin.198227027Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue27July 6, 1982 RelatedInformation

The Mechanism of the Disintegration of Lead Dioxide Anodes under Conditions of Ozone Evolution in Strong Acid Electrolytes

not Available.

Electrochemical Syntheses, XVII [1]. Ozone Synthesis by Electrolysis of Water

Dimensionally stable lead dioxide anodes on a titanium substrate [2, 3] were tested for application in ozone electrosynthesis in a variety of aqueous electrolytes. At room tem­perature an ozone concentration of up to 13% by weight in the anodic gas composed of O3 and O2 is attained by using an aqueous phosphate electrolyte.

無電解銅めっき廃液の電解酸化によるＣＯＤ除去

A fundamental investigation was carried out on electrolytic oxidation of the electroless copper plating waste. The electroless copper plating waste from which EDTA has been recovered still contains the unrecovered EDTA, formaldehyde, methanol and formic acid and is high in COD. Any of these components was readily oxidized using a lead dioxide anode at an anodic current density of 1-6 A/dm2 and at a pH of 1.0-7.0. Recovery of EDTA from the electroless copper plating waste followed by electrolytic oxidation under the same conditions as above reduced COD from 1, 400ppm to 10ppm and at the same time caused deposition of the residual metal ions on the cathode. Furthermore, the waste treated in this manner did not interfere with the subsequent chemical treatment for removal of heavy metals and could be discharged after such treatment.

ChemInform Abstract: PREPARATION AND APPLICATIONS OF GRAPHITE SUBSTRATE LEAD DIOXIDE (GSLD) ANODE

AbstractÜbersicht.

Preparation and Applications of Graphite Substrate Lead Dioxide (GSLD) Anode

The GSLD anodes have been developed for obtaining suitable size anodes for use in high amperage cells in the production of chlorates and perchlorates. The performance characteristics of the anodes in the preparation of chlorates and perchlorates are described. The use of the GSLD anode in other inorganic preparations like bromates iodates, and periodates is also included.

Bleidioxidverbundelektroden für die Elektrosynthese, I Abscheidung von β-Bleidioxid auf Titan / Leaddioxide Electrodes for Electrosynthesis, I Deposition of β-Leaddioxide on Titanium

Noble metal electrodes do not stand the tests for anodic electro syntheses in technical applications. Mainly due to the high oxygen overvoltage lead dioxide can act as substitute. A novel process for the preparation of lead dioxide coated titanium anodes is described. The important procedure is a treatment of the clean titanium surface with a Ti(IV)-containing solution. By scanning electron microscopy it is established that three dimensional nucleation takes place. Lead dioxide anodes prepared following this process until now have livetimes of better than 3400 hours

Lead dioxide anodes in the large scale production of potassium chlorate from potassium chloride

AbstractPotassium chlorate, which is used mainly in the manufacture of matches, was prepared by the electrolytic oxidation of potassium chloride in an 800 A cell using graphite substrate lead dioxide anode and stainless steel cathode. The cell was operated at an anode current density of 5 A/dm2, a temperature of 55 to 60 °C and a pH of 6.0 to 7.0. A current efficiency of 82 to 85% was obtained and an assay yield of 77% was realised for the recrystallised product. The cell voltage was 3.2 to 3.3 V with an energy consumption of 6.3 to 6.5 kWh (d.c.)/kg of potassium chlorate produced.The cell effluent, being clear and free from suspended impurities, could be processed further without filtration and pure potassium chlorate (>99%) was obtained by recrystallisation.

Lead dioxide anodes in the large scale production of potassium chlorate from potassium chloride

Lead dioxide anodes in the large scale production of potassium chlorate from potassium chloride

Anodic oxidation of phenolic compounds. Part III. Anodic hydroxylation of phenols. A simple general synthesis of 4-alkyl-4-hydroxycyclo-hexa-2,5-dienones from 4-alkylphenols

The oxidation of simple, monohydric phenols at a lead dioxide anode in aqueous sulphuric acid has been studied. The effects of current density, electrolysis time, pH, concentration of phenol, and method of anode preparation on conversion and product distribution have been investigated, and optimal conditions for anodic hydroxylation of simple phenols have been deduced. In all cases studied the hydroxy-group entered the 4-position: thus 4-substituted phenols gave 4-substituted 4-hydroxycyclohexa-2,5-dienones, and phenols without substituents at C-4 gave p-benzoquinones. The former reaction provides a simple and efficient synthesis of these cyclohexa-2,5-dienone derivatives. A mechanism involving hydrolysis of an anodically generated phenoxonium ion is suggested. Evidence is presented which indicates that the phenoxonium ion is formed by ‘chemical’ oxidation with anodically generated lead dioxide. The lead dioxide anode is superior to carbon, nickel, and platinum anodes for hydroxylation.

Large-scale preparation of perchlorates directly from sodium chloride

Based on the optimum conditions arrived at in the laboratory experiments, large-scale trials have been carried out for the preparation of sodium perchlorate by the direct oxidation of sodium chloride in a single step using a graphite substrate lead dioxide anode.

Electrolytic Production of Perchlorate by Lead Dioxide Anodes

An outline is given of an electrolytic process for the production of sodium perchlorate using a pure lead dioxide anode. In this process, a saturated solution of sodium chlorate is electrolyzed batchwise at an anodic current density of 25 amp/dm2 at 50°C; current efficiency, about 70% with more than 99% conversion of chlorate to perchlorate; cell voltage, 4.5–5.0v. The process has been operated successfully for more than two years without renewal of the anodes. In relation to the above, the results of basic research on anode potential and current efficiency for perchlorate formation from chlorate are also given.

Electrosynthesis of nicotinic acid from 8-hydroxyquinoline

Electrochemical oxidation of 8-hydroxyquinoline at a lead dioxide anode in sulfuric acid gives quinolinic acid, which is decarboxylated to nicotinic acid.

Oxygen overpotential of graphite-substrate lead dioxide anode

Oxygen overpotential of graphite-substrate lead dioxide anode

Improvement in the Electrolytic Preparation of lodoform

Use of lead dioxide anode with a graphite substrate in the electrolytic preparation of iodoform is described. Influence of bath composition, current density, temperature, and pH on the current efficiency has been investigated. Results are compared with those obtained with the conventional anodes like platinum and graphite. The effect of rotation of the anode is discussed.

Electrolytically Regenerated Ceric Sulfate for the Oxidation of Organic Compounds. I. Oxidation of p-Xylene to p-Tolualdehyde

Abstract 1. The current efficiency for the oxidation of cerous sulfate in sulfuric acid at a lead dioxide in an undivided cell was generally found to be 70%. 2. By using a paste of cerous sulfate in sulfuric acid, ceric sulfate reagent is obtained in a concentrated form. 3. A kinetic study of the oxidation of p-xylene by ceric sulfate is described and apparent energy of activation is calculated. 4. The process of oxidation of p-xylene to p-tolualdehyde is made cyclic and continuous by regeneration of ceric sulfate at a lead dioxide anode.