Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Electrolysis

  • water electrolysis

  • Terms modified by Electrolysis

  • electrolysis cell
  • electrolysis time

  • Selected Abstracts

    Intermediate Temperature Reversible Fuel Cells

    Singaravelu Elangovan
    Electrolysis of water produces high-purity hydrogen directly, with no need for additional clean-up process. Efficiency and cost of electrolysis are favorable with high-temperature steam electrolyzers where a portion of the required energy can be supplied as thermal energy. With the similarity in requirements, much of the materials and designs aspects for the high-temperature electrolyzers have been derived from solid oxide fuel cell development. Lanthanum gallate electrolyte-based cells were evaluated in fuel cell and electrolysis modes of operation. A modified nickel anode is shown to lower the reactivity with the gallate. [source]

    Electrochemical Deodorization and Disinfection of Hog Manure

    Dorin Bejan
    Abstract Electrolysis of liquid hog manure under direct current achieved amelioration of odour, in terms of both odour quality and odour intensity, and simultaneously reduced the population of odour-causing bacteria by two orders of magnitude. A comparison of anode materials indicated that hydroxyl radical-forming anodes (boron-doped diamond and Ebonex) were the most effective, but unfortunately these materials are not yet available commercially in large size format. Dimensionally stable anodes composed of Ti/IrO2 were found to be satisfactory; lead-based anodes leached unacceptable quantities of inorganic lead into the treated manure, and graphite anodes tended to disintegrate on long-term use. The mechanism of action of the bactericidal effect involves a combination of toxicity by O2 that is released at the anode and hypochlorination due to the chloride ion that is present in manure. The proposed technology was shown to be successful at the 27 L scale in an on-farm demonstration. L'électrolyse du purin de porc liquide avec un courant continu a permis d'améliorer l'odeur, tant en qualité qu'en intensité, et simultanément, de réduire la population de bactéries à l'origine de l'odeur de deux ordres de grandeur. Une comparaison des matériaux anodiques indique que les anodes formant des radicaux libres d'hydroxyle (diamant amélioré au bore et Ebonex) sont les plus efficaces, mais malheureusement ces matériaux ne sont pas encore disponibles en grand quantité dans le commerce. On a trouvé que des anodes dimensionnellement stables composées de Ti/IrO2 étaient satisfaisantes, tandis que les anodes à base de plomb ont donné des quantités inacceptables de plomb lixivié non organique dans le purin traité et les anodes graphites tendent à se désintégrer avec une utilisation prolongée. Le mécanisme d'action de l'effet bactéricide implique une combinaison de toxicité par l'O2 qui est libéré à l'anode et par l'hypochloruration à cause de l'ion de chlorure présent dans le purin. On montre que la technologie proposée est un succès dans une démonstration à l'échelle de 27 L dans une ferme [source]

    Use of electrolysis as an adjunct to liver resection

    B. G. Fosh
    Background: Patients with hepatic metastases are potentially curable if all the diseased tissue can be resected. Unfortunately, only 10,20 per cent of patients are suitable for curative resection. Electrolysis is a novel non-thermal method of tissue ablation. When used in conjunction with surgery it may increase the number of resectable liver tumours with curative treatment. Methods: All patients had been deemed inoperable using currently accepted criteria. Nine patients with hepatic deposits from colorectal carcinoma underwent combined surgical resection and electrolytic ablation of metastases. Results: The treatment was associated with minimal morbidity. Within the electrolytically treated area seven patients had no radiological evidence of recurrence at a median follow-up of 9 (range 6,43) months; local recurrence was detected in two patients. Six of the nine patients had metastases elsewhere in the liver with four having extrahepatic metastases. Three patients remain tumour free. Three patients died. The median survival was 17 (range 9,24) months from the time of treatment. Discussion: Electrolysis with resection may confer a disease-free and overall survival benefit. The small size of this initial study precludes statistical analysis, but preliminary results are encouraging. © 2002 British Journal of Surgery Society Ltd [source]

    The Mechanism of Water Oxidation: From Electrolysis via Homogeneous to Biological Catalysis

    CHEMCATCHEM, Issue 7 2010
    Holger Dau Prof.
    Abstract Striving for new solar fuels, the water oxidation reaction currently is considered to be a bottleneck, hampering progress in the development of applicable technologies for the conversion of light into storable fuels. This review compares and unifies viewpoints on water oxidation from various fields of catalysis research. The first part deals with the thermodynamic efficiency and mechanisms of electrochemical water splitting by metal oxides on electrode surfaces, explaining the recent concept of the potential-determining step. Subsequently, novel cobalt oxide-based catalysts for heterogeneous (electro)catalysis are discussed. These may share structural and functional properties with surface oxides, multinuclear molecular catalysts and the catalytic manganese,calcium complex of photosynthetic water oxidation. Recent developments in homogeneous water-oxidation catalysis are outlined with a focus on the discovery of mononuclear ruthenium (and non-ruthenium) complexes that efficiently mediate O2 evolution from water. Water oxidation in photosynthesis is the subject of a concise presentation of structure and function of the natural paragon,the manganese,calcium complex in photosystem,II,for which ideas concerning redox-potential leveling, proton removal, and OO bond formation mechanisms are discussed. The last part highlights common themes and unifying concepts. [source]

    Reduction of the Water Demand in the Process Industry by Production-Integrated Application of the Catalytic Electrolysis,

    M. Forstmeier
    In many process industry applications fresh water demand can be reduced significantly by production-integrated electrolytic disinfection of the process water. This contribution deals with the basic principles of electrolytic water disinfection and presents two case studies: application of the proposed method during the production of liquid detergents and during a metallurgical production process. [source]

    ChemInform Abstract: Reactions of Some Arenes and Pyrazoles in MeCN under Conditions of Undivided-Cell Electrolysis.

    CHEMINFORM, Issue 16 2002
    V. A. Chauzov
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Electrochemical reduction of benzoylformic acid in ionic liquid

    Jia-Xing Lu
    Abstract Ionic liquids possess a number of unique properties that make them ideal electrolytes. Electrochemical reduction of benzoylformic acid in room temperature ionic liquids as reaction media could be conducted with excellent performances without any additional supporting electrolyte. Electrolysis at glassy carbon electrode results in the formation of mandelic acid in 91% yield. And the electrochemical behavior of benzoylformic acid was investigated with the technique of cyclic voltammetry. [source]

    The Art of Repair in Surgical Hair Restoration,Part II: The Tactics of Repair

    Robert M. Bernstein MD
    background. As patient awareness of new hair transplantation techniques grows, the repair of improperly planned or poorly executed procedures becomes an increasingly important part of surgical hair restoration. objective. Part II of this series is written to serve as a practical guide for surgeons who perform repairs in their daily practices. It focuses on specific repair techniques. methods. The repairs are performed by excision with reimplantation and/or by camouflage. Follicular unit transplantation is used for the restorative aspects of the procedure. results. Using punch or linear excision techniques allows the surgeon to relocate poorly planted grafts to areas that are more appropriate. The key elements of camouflage include creating a deep zone of follicular units, angling grafts in their natural direction, and using forward and side weighting of grafts to increase the appearance of fullness. In special situations, removal of grafts without reimplantation can be accomplished using lasers or electrolysis. conclusion. Meticulous surgical techniques and optimal utilization of a limited hair supply will enable the surgeon to achieve the best possible cosmetic results for patients requiring repairs. [source]

    The Art of Repair in Surgical Hair Restoration Part I: Basic Repair Strategies

    Robert M. Bernstein MD
    background. An increasingly important part of many hair restoration practices is the correction of hair transplants that were performed using older, outdated methods, or the correction of hair transplants that have left disfiguring results. The skill and judgment involved in these repair procedures often exceed those needed to operate on patients who have had no prior surgery. The use of small grafts alone does not protect the patient from poor work. Errors in surgical and aesthetic judgment, performing procedures on noncandidate patients, and the failure to communicate successfully with patients about realistic expectations remain major problems. objective. This two-part series presents new insights into repair strategies and expands upon several techniques previously described in the hair restoration literature. The focus is on creative aesthetic solutions to solve the supply/demand limitations inherent in most repairs. This article is written to serve as a guide for surgeons who perform repairs in their daily practices. methods. The repairs are performed by excision with reimplantation and/or by camouflage. Follicular unit transplantation is used for the restorative aspects of the procedure. results. Using punch or linear excision techniques allows the surgeon to relocate poorly planted grafts to areas that are more appropriate. In special situations, removal of grafts without reimplantation can be accomplished using lasers or electrolysis. The key elements of camouflage include creating a deep zone of follicular units, angling grafts in their natural direction, and using forward and side weighting of grafts to increase the appearance of fullness. The available donor supply is limited by hair density, scalp laxity, and scar placement. conclusion. Presented with significant cosmetic problems and severely limited donor reserves, the surgeon performing restorative hair transplantation work faces distinct challenges. Meticulous surgical techniques and optimal utilization of a limited hair supply will enable the surgeon to achieve the best possible cosmetic results for patients requiring repairs. [source]

    Comparison of DNA-Reactive Metabolites from Nitrosamine and Styrene Using Voltammetric DNA/Microsomes Sensors

    ELECTROANALYSIS, Issue 9 2009
    Sadagopan Krishnan
    Abstract Voltammetric sensors made with films of polyions, double-stranded DNA and liver microsomes adsorbed layer-by-layer onto pyrolytic graphite electrodes were evaluated for reactive metabolite screening. This approach features simple, inexpensive screening without enzyme purification for applications in drug or environmental chemical development. Cytochrome P450 enzymes (CYPs) in the liver microsomes were activated by an NADPH regenerating system or by electrolysis to metabolize model carcinogenic compounds nitrosamine and styrene. Reactive metabolites formed in the films were trapped as adducts with nucleobases on DNA. The DNA damage was detected by square-wave voltammetry (SWV) using Ru(bpy) as a DNA-oxidation catalyst. These sensors showed a larger rate of increase in signal vs. reaction time for a highly toxic nitrosamine than for the moderately toxic styrene due to more rapid reactive metabolite-DNA adduct formation. Results were consistent with reported in vivo TD50 data for the formation of liver tumors in rats. Analogous polyion/ liver microsome films prepared on 500,nm silica nanoparticles (nanoreactors) and reacted with nitrosamine or styrene, provided LC-MS or GC analyses of metabolite formation rates that correlated well with sensor response. [source]

    Microdimensional Polyaniline: Fabrication and Characterization of Dynamics of Charge Propagation at Microdisk Electrodes

    ELECTROANALYSIS, Issue 17 2004
    Karolina Caban
    Abstract We describe fabrication of microdimensional polyanilne films in a controlled manner by voltammetric potential cycling or controlled potential electrolysis on platinum microdisk electrodes. The film grows in a form of hemispherical microdeposits, and its size largely exceeds the size of a Pt microdisk. Consequently, the film covers both the Pt substrate as well as the surrounding glass seal. Since the adhering polyaniline layer is conducting, the latter situation may lead to an increase in the effective electrode surface area. The lateral growth of polyaniline films outside the microdisk has also been demonstrated by performing diagnostic voltammetric experiments with use of a double microdisk set-up in which independent polarization of each disk is feasible. Microelectrode-based chronocoulometry, that involves an uncomplicated well-defined reduction potential step starting from the emeraldine (conducting) form and ending at leucoemeraldine (nonconducting) form, yields (upon application of a sufficiently short pulse) a well-defined linear response of charge versus square root of time that is consistent with the linear effective diffusion as the predominant charge propagation mechanism. When describing the system kinetics in terms of the effective (apparent) diffusion coefficient, we expect this parameter to be on the level of 10,8,cm2 s,1 or lower. The relative changes in dynamics of charge transport are discussed with respect to the polyaniline film loading, the size of microdisk electrode, expansion of the active electrode area, and the choice of electrolyte (strong acid) anion. The results are consistent with the view that when Pt microelectrode is modified with PANI deposit exceeding the size of the microdisk substrate, it behaves in a way as if its surface area is effectively much larger than the geometric area of Pt microdisk. [source]

    Reaction with N,N -Diethyl- p -phenylenediamine: A Procedure for the Sensitive Square-Wave Voltammetric Detection of Chlorine

    ELECTROANALYSIS, Issue 8 2003
    Hugo Seymour
    Abstract The reaction of chlorine and N,N -diethyl- p -phenylenediamine has been studied as a means of generating an analytical voltammetric signal of much improved sensitivity and selectivity for the detection of the former than is possible via direct electrolysis. A reaction mechanism is suggested whereby the chlorine attacks the primary amine of DEPD to form the N -chlorinated product that shows a much enhanced signal under conditions of square-wave voltammetry than does chlorine itself. The analytical parameters were found to vary with concentration of DEPD and a linear range from 17 to 495,,M was achievable with a corresponding limit of detection of 6.8,,M [source]

    Polychlorinated naphthalenes and other dioxin-like compounds in Elbe River sediments

    Werner Brack
    Abstract Contamination of Elbe River (Germany) sediments with dioxin-like toxicants was investigated following the 500-year flood (flood that statistically occurs once in 500 years) of 2002. It was hypothesized that large amounts of particulate matter from river beds and associated dioxin-like toxicants were mobilized and transported during this flood event. The investigation focused on polychlorinated naphthalenes (PCNs) that have not been determined previously in the Elbe River. The in vitro H4IIE- luc assay was used as an overall measure for toxicants capable of binding to the aryl hydrocarbon receptor (AhR). The assay was combined with congener-specific instrumental analyses and fractionation to quantify PCN contributions to total AhR-mediated activity relative to polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). Penta- to octachloron-aphthalene concentrations of 30 ng/kg dry weight up to 13 ,g/kg dry weight were found in Elbe River sediments downstream of Bitterfeld. Concentrations of penta- to octachloronaphthalenes, however, were only approximately 3 ,g/kg dry weight at a site in the vicinity of Bitterfeld, where a level of approximately 3 mg/kg dry weight was reported before the flood. Also, the congener pattern of PCNs at this site changed after the flood, and PCN patterns reported previously for Bitterfeld and assigned to chlor-alkali electrolysis with graphite electrodes could now be observed at the sites from downstream of Bitterfeld and Magdeburg. Whereas PCDD/Fs dominated the dioxin-like activity in the middle and lower Elbe River, PCNs contributed as much as 10% of the total AhR-mediated activity. The contribution of PCBs was less significant (maximum, 0.2%). Thus, in Elbe River sediments, PCNs should be considered as relevant contaminants and be included in future monitoring and risk assessment programs. [source]

    Chemical and Electrochemical Behaviours of a New Phenolato-Bridged Complex [(L)MnIIMnII(L)]2+.

    Dinuclear Mono-µ-Oxido [(L)MnIII(µ-O)MnIII/IV(L)]2+/3+ Species, Pathways to Mononuclear Chlorido [(L)MnII/III/IVCl]0/1/2+
    Abstract The X-ray structure of a new dinuclear phenolato-bridged Mn2II complex abbreviated as [(L)MnMn(L)]2+ (1), where LH is the [N4O] phenol containing ligand N,N -bis(2-pyridylmethyl)- N, -salicylidene-ethane-1,2-diamine ligand, is reported. A J value of ,3.3 cm,1 (H = ,J,1·,2) was determined from the magnetic measurements and the 9.4 GHz EPR spectra of both powder and frozen acetonitrile solution samples were analyzed with temperature. The cyclic voltammetry of 1 displays a reversible anodic wave at E1/2 = 0.46 V vs. SCE associated with the two-electron oxidation of 1 yielding the dinuclear Mn2III complex [(L)MnMn(L)]4+ (2). The easy air oxidation of 1 gives the mono-,-oxido Mn2III complex [(L)Mn(, - O)Mn(L)]2+ (3). A rational route to the formation of the mixed-valence Mn2III,IV complex [(L)Mn(, - O)Mn(L)]3+ (4) starting from 1 by bulk electrolysis at EP = 0.75 V vs. SCE in the presence of one equiv. of base per manganese ion is also briefly reported. Addition of chloride ions to 1 led to the cleavage of the phenolato bridges to give the mononuclear MnII complex [(L)MnCl] (5). Cyclic voltammetry of 5 displays two reversible anodic waves at E1/2 = 0.21 and E1/2 = 1.15 V vs. SCE, assigned to the two successive one-electron abstractions giving the MnIII and MnIV species [(L)MnCl]+ (6) and [(L)MnCl]2+ (7), respectively. The electronic signatures from UV/Visible and EPR spectroscopy of the electrochemically prepared samples of 6 and 7 confirmed the respective oxidation states. For instance, 7 displays a broad and intense absorption band characteristic of a phenolato to MnIV charge-transfer transition at 690 nm (2000 M,1,cm,1) and its 9.4 GHz EPR spectrum shows a strong transition at g = 5.2 consistent with a rhombically distorted S = 3/2 system with a zero-field splitting dominating the Zeeman effect. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Nitrate- and Nitrite-Assisted Conversion of an Acetonitrile Ligand Into an Amidato Bridge at an {Mo2(Cp)2(,-SMe)3} Core: Electrochemistry of the Amidato Complex [Mo2(Cp)2(,-SMe)3{,-,1,,1 -OC(Me)NH}]+

    Marc Le Hénanf
    Abstract Treatment of [Mo2(Cp)2(,-SMe)3(MeCN)2]+ (1+) with NO3, or NO2, results in the conversion of one terminally bound acetonitrile ligand into an amidato bridge. The reaction produces [Mo2(Cp)2(,-SMe)3{,-,1,,1 -OC(Me)NH}]0/+ (20/+) and involves the formation of an intermediate, which was detected by cyclic voltammetry but which could not be isolated, and which likely arises from the substitution of the NOx anion for one MeCN ligand. The electrochemical behaviour of 2+ was studied by cyclic voltammetry in THF and MeCN. The reduction of 2+ in the presence of acid (HBF4/H2O or HBF4/Et2O) in these solvents leads to the release of the amidate bridge. Controlled-potential electrolysis of 2+ in MeCN in the presence of acid produces 1+ quantitatively; the charge consumed (>1 F,mol,1 of 1+) indicates that electrons are also used to reduce protons. This was confirmed by the formation of 2+ (in variable amounts depending on the conditions) on treating 2 with acid. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    EPR Insensitivity of the Metal-Nitrosyl Spin-Bearing Moiety in Complexes [LnRuII -NO·]k

    Stéphanie Frantz
    Abstract A survey of 18 paramagnetic species [LnRu(NO)]k, including seven new examples studied by in situ electrolysis, reveals a surprisingly narrow range of EPR parameters despite a wide variety of ligands such as pyridine, polypyridines, imines, amines, nitriles, phosphanes, carbonyl, cyclopentadienides, halides, hydride, hydroxide, thiocyanate or cyanide: g1 = 2.015 ± 0.02, g2 = 1.990 ± 0.015, g3 = 1.892 ± 0.03, gav = 1.968 ± 0.02, ,g = g1 , g3 = 0.122 ± 0.037, A2(14N) = 3.3 ± 0.5 mT. This rather small variability, smaller still if the organometallic compounds are excluded, differs from the wider range of EPR data reported for nitrosyliron species with S = 1/2; apparently, the {RuNO}7 configuration involves a rather invariant and relatively covalent metal,NO interaction. DFT calculations were employed for [(NC)5Ru(NO)]3, to reproduce the EPR data, to evaluate the spin distribution (58% spin density on NO), and to reveal structural changes on reduction such as the Ru,N,O bending and Ru,NO bond lengthening. In addition, the possibility of staggered and eclipsed conformations is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Thermodynamic Study of ,H Complexes in Nucleophilic Aromatic Substitution Reactions: Relative Stabilities of Electrochemically Generated Radicals

    Iluminada Gallardo
    Abstract The mechanism for the electrochemical oxidation of ,H complexes, such as 1-hydro-1-alkoxy/sulfoxy or -fluoro-2,4-dinitro/2,4,6-trinitrocyclohexadienyl anions, has been widely studied by means of cyclic voltammetry and controlled-potential electrolysis. Previous studies have shown that the electrochemical oxidation of ,H complexes, formed by the addition of carbon or nitrogen nucleophiles followed by a two electron mechanism, corresponding to the formal elimination of the hydride anion (nucleophilic aromatic substitution of hydrogen mechanism, the NASH mechanism). For these ,H complexes (Nu, = OH,, ,OR, ,SR, ,F), the electrochemical reaction takes place by a one-electron mechanism and is followed by the radical elimination of the leaving group with the consequent recovery of the starting material. This mechanism is similar to that proposed for the electrochemical oxidation of ,X complexes (nucleophilic aromatic substitution of a heteroatom, the NASX mechanism). The operating mechanism in each case, the NASH or NASX, can be rationalized in terms of thermodynamics. The standard potentials of the , complex and/or the leaving group as well as the bond dissociation energies (BDEs) are determinant factors. This study has not led to a significant improvement in the electrochemical preparation of aromatic-substituted compounds, but does help to understand and predict the usefulness or uselessness of using the nucleophilic aromatic substitution route to obtain a desired product. Finally, the current approach extends the electrochemical methodology to different chemical fields, for example, to general nondestructive methods for the detection, identification, and quantification of either organic pollutants or explosives in different solvents. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Mesoporous Hydrous Manganese Dioxide Nanowall Arrays with Large Lithium Ion Energy Storage Capacities

    Dawei Liu
    Abstract Novel nanowall arrays of hydrous manganese dioxide MnO2,·,0.5H2O are deposited onto cathodic substrates by the potentiostatic method from a mixed aqueous solution of manganese acetate and sodium sulfate. The deposition is induced by a change of local pH resulting from electrolysis of H2O, and hierarchical mesoporous nanowall arrays are formed as a result of simultaneous precipitation of manganese hydroxide and release of hydrogen gas bubbles from the cathode. The morphology and lithium ion intercalation properties are found to change appreciably with the concentration of the precursor electrolyte, with a significant reduction in specific surface area with an increased precursor concentration. For example, mesoporous nanowall arrays deposited from 0.1,M solution possess a surface area of ,96,m2 g,1 and exhibit a stable high intercalation capacity of 256,mA hg,1 with a film of 0.5,µm in thickness, far exceeding the theoretical limit of 150,mA hg,1 for manganese dioxide bulk film. Such mesoporous nanowall arrays offer much greater energy storage capacity (e.g., ,230,mA hg,1 for films of ,2.5,µm) than that of anodic deposited films of the same thickness (,80,mA hg,1). Such high lithium ion intercalation capacity and excellent cyclic stability of the mesoporous nanowall arrays, especially for thicker films, are ascribed to the hierarchically structured macro- and mesoporosity of the MnO2,·,0.5H2O nanowall arrays, which offer large surface to volume ratio favoring interface Faradaic reactions, short solid-state diffusion paths, and freedom to permit volume change during lithium ion intercalation and de-intercalation. [source]

    Formation of Highly Crystallized ,-PbO Thin Films by Cathodic Electrodeposition of Pb and Its Rapid Oxidation in Air,

    S. Sawatani
    Abstract The process of electrodeposition of ,-PbO thin films from aqueous solutions of PbII salts has been studied in detail. Contrary to the mechanism assumed in previous studies, thin films of crystalline ,-PbO are obtained after cathodic electrolysis in aqueous solutions of various soluble salts of PbII (Pb(NO3)2, Pb(ClO4)2, and Pb(CH3COO)2), and in both the presence and the absence of O2, thus indicating no contribution of OH, generation by electroreduction of NO3, and/or O2 to the formation of ,-PbO. A gradual color change is noted: a freshly electrodeposited gray film turns yellow as it dries in air. Drying of the films under controlled atmosphere (Ar or O2), combined with scanning electron microscopy (SEM) observation and X-ray diffraction (XRD) measurement, has revealed that freshly deposited films are of metallic Pb, which are oxidized and converted into ,-PbO. Such a reaction is operative only when a freshly electrodeposited activated wet Pb film is in contact with gaseous O2. Despite the rapid conversion of a solid material, the resultant ,-PbO thin films are highly crystallized and possess highly ordered internal nanostructure. Elongated nanoparticles (30,nm,×,100,nm) are assembled in a regular alignment to compose a large platelet (greater than 10,,m in size) with single-crystalline character, as revealed by transmission electron microscopy (TEM) observation and selected-area electron diffraction (SAED) measurement. [source]

    Intermediate Temperature Reversible Fuel Cells

    Singaravelu Elangovan
    Electrolysis of water produces high-purity hydrogen directly, with no need for additional clean-up process. Efficiency and cost of electrolysis are favorable with high-temperature steam electrolyzers where a portion of the required energy can be supplied as thermal energy. With the similarity in requirements, much of the materials and designs aspects for the high-temperature electrolyzers have been derived from solid oxide fuel cell development. Lanthanum gallate electrolyte-based cells were evaluated in fuel cell and electrolysis modes of operation. A modified nickel anode is shown to lower the reactivity with the gallate. [source]

    Geothermal-based hydrogen production using thermochemical and hybrid cycles: A review and analysis

    M. Tolga Balta
    Abstract Geothermal-based hydrogen production, which basically uses geothermal energy for hydrogen production, appears to be an environmentally conscious and sustainable option for the countries with abundant geothermal energy resources. In this study, four potential methods are identified and proposed for geothermal-based hydrogen production, namely: (i) direct production of hydrogen from the geothermal steam, (ii) through conventional water electrolysis using the electricity generated through geothermal power plant, (iii) by using both geothermal heat and electricity for high temperature steam electrolysis and/or hybrid processes, and (iv) by using the heat available from geothermal resource in thermochemical processes. Nowadays, most researches are focused on high-temperature electrolysis and thermochemical processes. Here we essentially discuss some potential low-temperature thermochemical and hybrid cycles for geothermal-based hydrogen production, due to their wider practicality, and examine them as a sustainable option for hydrogen production using geothermal heat. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and attractive overall system efficiencies over 50% based on a complete reaction approach. The copper-chlorine cycle is identified as a highly promising cycle for geothermal-hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Study of a fuel cell network with water electrolysis for improving partial load efficiency of a residential cogeneration system

    S. Obara
    Abstract A fuel cell energy network which connects hydrogen and oxygen gas pipes, electric power lines and exhaust heat output lines of the fuel cell cogeneration for individual houses, respectively, is analysed. As an analysis case, the energy demand patterns of individual houses in Tokyo are used, and the analysis method for minimization of the operational cost using a genetic algorithm is described. The fuel cell network system of an analysis example assumed connecting the fuel cell cogeneration of five houses. If energy is supplied to the five houses using the fuel cell energy network proposed in this paper, 9% of city gas consumption will be reduced by the maximum from the results of analysis. Two per cent included with 9% is an effect of introducing water electrolysis operation of the fuel cells, corresponding to partial load operation of fuel cell cogeneration. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Investigation of the electropolymerization of o -toluidine and p -phenylenediamine and their electrocopolymerization by in situ ultraviolet,visible spectroelectrochemistry

    Guirong Zhang
    Abstract Under the conditions of potentiostatic electrolysis, the electropolymerization of o -toluidine (OT) and para -phenylenediamine (PPDA) and the electrocopolymerization between OT and PPDA on an indium tin oxide (ITO) conductive glass electrode at potentials of 0.7, 0.8, and 0.9 V were studied in detail by in situ ultraviolet,visible (UV,vis) spectrometry in 0.5 mol/L sulfuric acid media. It was shown that both OT and PPDA could be electropolymerized on the ITO electrode, which depended on the applied electrolysis potential and the concentration of the monomer. Furthermore, in situ UV,vis spectra indicated that the electrocopolymerization between OT and PPDA could happen. The presence of PPDA not only promoted polymerization but also accelerated polymerization, which was attributed to the formation of an intermediate result from the coupling of PPDA and the toluidine monomer cation radical. PPDA could be incorporated into the copolymer to make the copolymer have a phenazine or phenazine-like cyclic structure, which was proven by the reflectance Fourier transform infrared spectra of the polymer and copolymer. The scanning electron microscopy morphology images of the polymers obtained showed that, in addition to accelerating polymerization, PPDA also could change the method of nucleation for the polymer to make the copolymer possess a fibrous surface morphology. The diameter of the fibroid copolymer was about 100 nm, and the length of that reached about 1000 nm. In the article, a newer concerned mechanism of copolymerization was proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Electrolytic removal of ammonia from brine wastewater: scale-up, operation and pilot-scale evaluation

    Catalino G Alfafara
    Abstract Brine wastewater with a high ammonia content from an iodine processing plant (commonly called kansui in Japan) was treated by electrolysis. The system, which can be considered as an indirect electrolytic treatment process, generates chlorine at the anodes and initiates the formation of mixed oxidants like hypochlorous acid. The oxidants then act as agents for ammonia destruction. Laboratory-scale experiments showed that high ammonia concentrations (as much as 200 mg dm,3) could be completely removed within a few minutes, and could be considered a good alternative for efficient ammonia removal from saline wastewaters. From laboratory-scale experiments in the batch and continuous modes, the charge dose was analyzed and used as the operating and scale-up factor. The value of the charge dose was not severely affected by changes in operating conditions such as electrode spacing and temperature. The charge dose from batch and continuous runs was found to be in the range of 23 C (mg NH4 -N removed),1 to 29 C (mg NH4 -N removed),1. Using the charge dose obtained from laboratory-scale continuous electrolysis experiments as the scale-up factor, a pilot-scale reactor was designed, and the operating conditions were calculated. In the pilot-scale reactor tests at different flow rates, the effluent ammonia concentrations were reasonably close to the calculated values predicted from the charge dose equation. Copyright © 2004 Society of Chemical Industry [source]

    Use of various processes for pilot plant treatment of wastewater from a wood-processing factory

    Nikolaos S Athanasopoulos
    Abstract The wastewater from a wood-processing factory is characterized by a high COD, chlorides and nitrogen content. Various treatment processes were applied to treat this wastewater in pilot-scale units. By applying one-stage denitrification,activated sludge biological treatment it was not possible to remove nitrogen. Nitrification was inhibited by wastewater compounds. By applying a second stage of a nitrification biofilter it was possible to have a high degree of nitrification. The denitrification was complete. With biological methods the reduction of COD, and -N and -N concentrations to acceptable values was not achievable. Physical,Chemical methods as H2O2/UV, electrolysis and ozonation were used as post-treatment of effluents from the biological system. Radical degradation, initiated by the powerful hydroxyl radicals which are generated from H2O2 by UV activation, is used for wastewater post-treatment. The combination of H2O2/UV was not suitable for post-treatment of this wastewater. With electrolysis, -N and COD removal can be complete. The total amount of ammonia and organic nitrogen converted to nitrate nitrogen for current density of 1.15,Adm,2 and energy consumption of 71.6,kWhm,3 was 0.35,gdm,3. Further biological denitrification is required for -N removal to permitted values. Energy consumption for the elimination of 1,kg COD was 40.4,kWh and 35.8,kWh for current densities of 0.7,Adm,2 and 1.15,Adm,2 respectively. The energy required to reach the limit value of COD equal to 150,mgdm,3 for current density of 1.15,Adm,2 was 71.6,kWhm,3. With ozonation, the COD removal can be complete. Further biological nitrification,denitrification is required to remove -N and -N to permitted values. At pH 7.0, in order to reach the limit value of COD equal to 150,mgdm,3, specific ozone dose was 6.0,g per g of COD removed and the total amount of ammonia and organic nitrogen converted to nitrate nitrogen was 0.25,gdm,3. The total equivalent energy required is estimated to be 75.0,kWhm,3. © 2001 Society of Chemical Industry [source]

    Synthesis ,-aminonitrile through anodic cyanation of N -benzylpiperidine

    Ping Zhao
    Six-membered cyclic ,-aminonitrile has been prepared from anodic cyanation of N -benzylpiperidine. Good yields of ,-aminonitriles could be obtained through potentiostatic electrolysis under different conditions. The results also explain why high yield ,-aminonitriles could not be obtained under constant current electrolysis. [source]

    Polarization curves for an alkaline water electrolysis at a small pin vertical electrode to produce hydrogen,

    AICHE JOURNAL, Issue 9 2010
    Ph. Mandin
    Abstract During two-phase electrolysis for hydrogen production, according with alkaline,water electrolysis process, there are bubbles which are created at electrodes which imply a great hydrodynamic acceleration in the normal earth gravity field and then a quite important electrical properties and electrochemical processes disturbance, for both transport and reaction. This disturbance can lead to the modification of the local current density and to anode effects for example. In this work, a model experimental set-up is studied. The vertical pine electrode of small electro active surface area is surrounded with a large surface counter electrode. The hydrogen production is performed at the working electrode and effort is focused here upon the global electrochemical cell electrical performances. The polarization curves intensity vs. applied voltage are experimentally measured and presented for different factors such as: the electro active species concentration, nature and counter electrode diameter factors. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source]

    Synthesis of N -methylmorpholine N -(17O-oxide) and N -methylmorpholine 15N -(17O-oxide)

    Martina Opietnik
    Abstract N -Methylmorpholine N -(17O-oxide) and N -methylmorpholine 15N -(17O-oxide) were prepared from N -methylmorpholine and 15N -methylmorpholine by oxidation with H217O2. The facile one-pot procedure provided yields of 82 and 76%, respectively. The labeled hydrogen peroxide was obtained by electrolysis of H217O followed by autoxidation of 2-ethylanthraquinol with the molecular oxygen 17O2 generated. The compounds serve for mechanistic studies into gold nanoparticle generation in NMMO solution. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Effect of gas evolution on mixing and conversion in a flow-through electrochemical reactor

    AICHE JOURNAL, Issue 9 2009
    Matthew A. Petersen
    Abstract Flow-through electrolytic reactors (FTER) emplaced below the subsurface may be used to control the migration of groundwater contamination away from source zones. During prior studies with FTERs, water electrolysis and associated gas generation have occurred concurrently with contaminant degradation. Gas evolution-induced mixing within the electrode assembly has the potential to impact system performance. A mathematical model of the system was developed to capture the impact of mixing on transport processes in the system. Corresponding transient and steady-state tracer experiments using ferricyanide as a model contaminant were conducted to quantify mixing-dependent parameters and verify modeling results. Over a range of relevant groundwater flowrates, Peclet numbers were between 0.1 and 10, indicating that mixing was a important process under low-flow conditions. Comparison of experiments and model calculations demonstrated that incorporating gas evolution into the model was necessary for accurate performance prediction. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    A promising method for electrodeposition of aluminium on stainless steel in ionic liquid

    AICHE JOURNAL, Issue 3 2009
    Guikuan Yue
    Abstract A promising method for aluminium deposition was proposed by using AlCl3/[bmim]Cl (1-butyl-3-methylimidazolium chloride) ionic liquid as electrolyte. By using this novel method, the volatile and flammable organic solvent systems and the high corrosive inorganic molten salts with high temperature can be substituted, and the deposit microstructure can be easily adjusted by changing the current density, temperature and electrolyte composition. The study was performed by means of galvano-static electrolysis and the optimum operating conditions were determined based on the systematic studies of the effects of current density, temperature, molar ratio of AlCl3 to [bmim]Cl, stirring speed and deposition time on the quality of deposited coatings. The electrical conductivities of electrolytes were also investigated as a function of temperature (298,358 K) and molar ratio of AlCl3 to [bmim]Cl (from 0.1:1 to 2.0:1). Dense, bright and adherent aluminium coatings were obtained over a wide range of temperature (298,348 K), current densities (8,44 mA/cm2) and molar ratio (1.6:1,2.0:1). Results from the analysis of crystal structure show that all of the electrodeposits exhibit a preferred (200) crystallographic orientation. Temperature has significant influence on the crystallographic orientation and there does not appear to be an apparent impact of current density on it. Analyses of the chronoamperograms indicate that the deposition process of aluminium on stainless steel was controlled by three-dimension nucleation with diffusion-controlled growth and there is a conversion from progressive nucleation to instantaneous nucleation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]