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1

Degradation of paraquat herbicide by electrochemical advanced oxidation methods  

Microsoft Academic Search

Various electrochemical advanced oxidation processes (EAOPs) including anodic oxidation (AO), electro-Fenton (EF) and photoelectro-Fenton (PEF) methods were applied to study the degradation of paraquat (1,1?-dimethyl-4,4?-bipyridinium dichloride), a highly toxic and widely used herbicide, in aqueous acidic solution at pH 3.0. After initial optimization studies, EAOPs were compared to classic Fenton treatment (CFT) for their effectiveness at mineralizing the herbicide solution.

Anissa Dhaouadi; Nafaâ Adhoum

2009-01-01

2

Electrochemical advanced oxidation process using DiaChem® electrodes  

Microsoft Academic Search

The electrochemical advanced oxidation process (EAOP) using boron doped diamond (DiaChem®, registered trademark of Condias GmbH) has been studied for wastewater treatment and drinking water disinfection. DiaChem® electrodes consist of preferentially metallic base materials coated with a conductive polycrystalline diamond film by hot-filament chemical vapour deposition. They exhibit high overpotential for water electrolysis as well as high chemical inertness and

I. Tröster; L. Schäfer; M. Fryda; T. Matthée

3

ELECTROCHEMICAL ADVANCED OXIDATION PROCESS UTILIZING NB-DOPED TIO2 ELECTRODES  

EPA Science Inventory

An electrochemical advanced oxidation process has been developed, utilizing electrodes which generate hydroxyl free radical (HO) by oxidizing water. All substrates tested are oxidized, mostly with reaction rates proportional to the corresponding rate constants for reaction with h...

4

ELECTROCHEMICAL ADVANCED OXIDATION PROCESS UTILIZING NB-DOPED TIO2 ELECTRODES  

EPA Science Inventory

An electrochemical advanced oxidation process has been developed utilizing electrodes which generate hydroxyl free radical (HO) by oxidizing water. All substrates tested are oxidized, mostly with reaction rates proportional to the corresponding rate constants for reaction with hy...

5

Electrochemical Advanced Oxidation Process Utilizing Nb-doped TiO2 Electrodes.  

National Technical Information Service (NTIS)

An electrochemical advanced oxidation process has been developed, utilizing electrodes which generate hydroxyl free radical (HO) by oxidizing water. All substrates tested are oxidized, mostly with reaction rates proportional to the corresponding rate cons...

O. Weres

2000-01-01

6

Treatment of an aqueous pesticides mixture solution by direct and indirect electrochemical advanced oxidation processes  

Microsoft Academic Search

In the present work, a comparative study on the degradation of a mixture of three pesticides (chlortoluron, carbofuran and bentazon) has been carried out by electrochemical advanced oxidation processes such as anodic oxidation and electro-Fenton using boron-doped diamond (BDD) anode. These processes are based on the in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation

Aida Kesraoui Abdessalem; Mehmet A. Oturan; Nihal Oturan; Nizar Bellakhal; Mohamed Dachraoui

2010-01-01

7

A comparison between Conductive-Diamond Electrochemical Oxidation and other Advanced Oxidation Processes for the treatment of synthetic melanoidins  

Microsoft Academic Search

In this study, three technologies classified as Advanced Oxidation Processes (Conductive-Diamond Electrochemical Oxidation (CDEO), ozonation and Fenton oxidation) have been compared to treat wastes produced in fermentation processes, and characterized by a significant color and a high organic load. Results of CDEO seem to strongly depend on the addition of an electrolyte salt, not only to decrease the energy cost

P. Cañizares; M. Hernández-Ortega; M. A. Rodrigo; C. E. Barrera-Díaz; G. Roa-Morales; C. Sáez

2009-01-01

8

Mineralization of 2,4-D by advanced electrochemical oxidation processes  

Microsoft Academic Search

The mineralization process for 2,4-dichlorophenoxyacetic acid (2,4-D) at pH ca. 3 has been studied by advanced electrochemical oxidation processes (AEOPs), such as electro-Fenton and photoelectro-Fenton processes, in which a Pt anode and a carbon–polytetrafluoroethylene O2-fed cathode, for in situ production of H2O2 are used. A solution of 230 ppm 2,4-D with a low salt content can be completely mineralized by

Enric Brillas; Juan C. Calpe; Juan Casado

2000-01-01

9

Degradation of the fluoroquinolone enrofloxacin by electrochemical advanced oxidation processes based on hydrogen peroxide electrogeneration  

Microsoft Academic Search

Solutions of the veterinary fluoroquinolone antibiotic enrofloxacin in 0.05M Na2SO4 of pH 3.0 have been comparatively degraded by electrochemical advanced oxidation processes such as anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF) at constant current density. The study has been performed using an undivided stirred tank reactor of 100ml and a batch recirculation flow

Elena Guinea; José Antonio Garrido; Rosa María Rodríguez; Pere-Lluís Cabot; Conchita Arias; Francesc Centellas; Enric Brillas

2010-01-01

10

A comparison between conductive-diamond electrochemical oxidation and other advanced oxidation processes for the treatment of synthetic melanoidins.  

PubMed

In this study, three technologies classified as Advanced Oxidation Processes (Conductive-Diamond Electrochemical Oxidation (CDEO), ozonation and Fenton oxidation) have been compared to treat wastes produced in fermentation processes, and characterized by a significant color and a high organic load. Results of CDEO seem to strongly depend on the addition of an electrolyte salt, not only to decrease the energy cost but also to improve efficiency. The addition of sodium chloride as supporting electrolyte improves the removal percentages of organic load, indicating the important role of mediated oxidation processes carried out by the electrogenerated oxidants (hypochlorite). Fenton oxidation and ozonation seem to be less efficient, and mainly Fenton oxidation favors the accumulation of refractory compounds. The differences observed can be explained in terms of the contribution of hydroxyl radicals and other specific oxidation mechanisms involved in each technology. PMID:18789836

Cañizares, P; Hernández-Ortega, M; Rodrigo, M A; Barrera-Díaz, C E; Roa-Morales, G; Sáez, C

2008-08-06

11

Oxidation\\/mineralization of 2Nitrophenol in aqueous medium by electrochemical advanced oxidation processes using Pt\\/carbon-felt and BDD\\/carbon-felt cells  

Microsoft Academic Search

Electrochemical degradation of toxic and persistent organic pollutant 2-Nitrophenol (2-NP) in acidic medium of pH 3 has been comparatively studied by electrochemical advanced oxidation processes (EAOPs) such as anodic oxidation using BDD anode (AO-BDD), electro-Fenton (EF-Pt) and anodic oxidation coupled to electro-Fenton (EF-BDD) processes under galvanostatic electrolysis conditions. The effect of current density and 2-NP initial concentration on the degradation

Nihal Oturan; Morched Hamza; Salah Ammar; Ridha Abdelhédi; Mehmet A. Oturan

2011-01-01

12

Treatment of winery wastewater by electrochemical methods and advanced oxidation processes.  

PubMed

The aim of this research was development of new system for the treatment of highly polluted wastewater (COD = 10240 mg/L; SS = 2860 mg/L) originating from vine-making industry. The system consisted of the main treatment that included electrochemical methods (electro oxidation, electrocoagulation using stainless steel, iron and aluminum electrode sets) with simultaneous sonication and recirculation in strong electromagnetic field. Ozonation combined with UV irradiation in the presence of added hydrogen peroxide was applied for the post-treatment of the effluent. Following the combined treatment, the final removal efficiencies of the parameters color, turbidity, suspended solids and phosphates were over 99%, Fe, Cu and ammonia approximately 98%, while the removal of COD and sulfates was 77% and 62%, respectively. A new approach combining electrochemical methods with ultrasound in the strong electromagnetic field resulted in significantly better removal efficiencies for majority of the measured parameters compared to the biological methods, advanced oxidation processes or electrocoagulation. Reduction of the treatment time represents another advantage of this new approach. PMID:23802163

Orescanin, Visnja; Kollar, Robert; Nad, Karlo; Mikelic, Ivanka Lovrencic; Gustek, Stefica Findri

2013-01-01

13

Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode  

Microsoft Academic Search

Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of

Sergi Garcia-Segura; Enric Brillas

2011-01-01

14

Electrochemical oxidation of chemical weapons  

Microsoft Academic Search

Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced

Surma

1994-01-01

15

ELECTROCHEMICAL ADVANCED OXIDATION TREATMENTS OF ACIDIC AQUEOUS SOLUTIONS CONTAINING THE AMINOACID ?-METHYLPHENYLGLYCINE USING A BORON-DOPED DIAMOND ANODE  

Microsoft Academic Search

The degradation of a solution containing 500 mg L-1 of the aminoacid ?-methylphenylglycine, 10 mg L-1 Fe2+ and 0.05 M Na2O4 at pH 3.0 has been studied by means of electrochemical advanced oxidation processes like electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) using an undivided electrolytic cell with a boron-doped diamond (BDD) anode and an O2-diffusion cathode. Under these conditions, very

Anna Serra; Xavier Domènech; José Peral; Conchita Arias; Enric Brillas

16

Mineralization of salicylic acid in acidic aqueous medium by electrochemical advanced oxidation processes using platinum and boron-doped diamond as anode and cathodically generated hydrogen peroxide  

Microsoft Academic Search

Solutions containing 164mgL?1 salicylic acid of pH 3.0 have been degraded by electrochemical advanced oxidation processes such as anodic oxidation, anodic oxidation with electrogenerated H2O2, electro-Fenton, photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Their oxidation power has been comparatively studied in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and a graphite or O2-diffusion cathode. In

Elena Guinea; Conchita Arias; Pere Lluís Cabot; José Antonio Garrido; Rosa María Rodríguez; Francesc Centellas; Enric Brillas

2008-01-01

17

Electrochemical advanced oxidation process for water treatment using DiaChem ® electrodes  

Microsoft Academic Search

Currently applied water treatment techniques consist of a combination of different methods to achieve the elimination of harmful pollutants. Within this field, the capability of electrochemical water treatment is still not exhaustively exploited due to the lack of for instance appropriate electrode materials. The chemical inertness and unique electrochemical properties of boron-doped diamond electrodes present great potential for electrochemical water

I. Tröster; M. Fryda; D. Herrmann; L. Schäfer; W. Hänni; A. Perret; M. Blaschke; A. Kraft; M. Stadelmann

2002-01-01

18

Electrochemical oxidation of chemical weapons  

SciTech Connect

Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced Concepts Program. The tests examined the effectiveness of CEO in destroying sarin (GB), a chemical nerve agent. The tests used 0.5 mL, 0.95 mL, and 1.0 mL of GB, corresponding to 544 mg, 816 mg, and 1,090 mg, respectively, of GB. Analysis of the off gas showed that, under continuous processing of the GB agent, destruction efficiencies of better than six 9s (99.9999% destroyed) could be achieved.

Surma, J.E.

1994-05-01

19

Mineralization of desmetryne by electrochemical advanced oxidation processes using a boron-doped diamond anode and an oxygen-diffusion cathode  

Microsoft Academic Search

The mineralization of acidic aqueous solutions of the herbicide desmetryne has been studied by electrochemical advanced oxidation processes (EAOPs) such as anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF) with UVA light. Electrolyses were conducted in an open and cylindrical cell with a boron-doped diamond (BDD) anode and an O2-diffusion cathode for H2O2 generation. The main oxidizing

Núria Borràs; Conchita Arias; Ramon Oliver; Enric Brillas

2011-01-01

20

Wastewaters by Electrochemical Advanced Oxidation Processes Using a BDD Anode and Electrogenerated H2O2 with Fe(II) and UVA Light as Catalysts  

Microsoft Academic Search

This paper reports the mineralization of an aromatic pharmaceutical as clofibric acid and the dye indigo carmine in 0.05 M Na 2SO 4 of pH 3.0 by electrochemical advanced oxidation processes such as anodic oxidation without and with electrogenerated H 2O2, electro-Fenton and photoelectro-Fenton using a boron-doped diamond (BDD) anode. These procedures produce the strong oxidant hydroxyl radical in the

E. Brillas; J. A. Garrido; R. M. Rodríguez; C. Arias; P. L. Cabot; F. Centellas

2007-01-01

21

Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode.  

PubMed

Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of Fe(2+) (AO-BDD-Fe(2+)) and under UVA irradiation (AO-BDD-Fe(2+)-UVA), along with electro-Fenton (EF-BDD), was tested. The oxidation of both acids and their iron complexes on BDD was clarified by cyclic voltammetry. AO-BDD allowed the overall mineralization of oxalic acid, but oxamic acid was removed much more slowly. Each acid underwent a similar decay in AO-BDD-Fe(2+) and EF-BDD, as expected if its iron complexes were not attacked by hydroxyl radicals in the bulk. The faster and total mineralization of both acids was achieved in AO-BDD-Fe(2+)-UVA due to the high photoactivity of their Fe(III) complexes that were continuously regenerated by oxidation of their Fe(II) complexes. Oxamic acid always released a larger proportion of NH(4)(+) than NO(3)(-) ion, as well as volatile NO(x) species. Both acids were independently oxidized at the anode in AO-BDD, but in AO-BDD-Fe(2+)-UVA oxamic acid was more slowly degraded as its content decreased, without significant effect on oxalic acid decay. The increase in current density enhanced the oxidation power of the latter method, with loss of efficiency. High Fe(2+) contents inhibited the oxidation of Fe(II) complexes by the competitive oxidation of Fe(2+) to Fe(3+). Low current densities and Fe(2+) contents are preferable to remove more efficiently these acids by the most potent AO-BDD-Fe(2+)-UVA method. PMID:21477836

Garcia-Segura, Sergi; Brillas, Enric

2011-03-21

22

Electrochemical oxidation of chlorophenols  

Microsoft Academic Search

Electrochemical 2-chlorophenol and 2,6-dichlorophenol removal from aqueous solutions using porous carbon felt anodes was investigated. Operating variables including current input, ratio between electrode and solution volumes, and initial pollutant concentration were considered in order to determine their influence on the faradic efficiency of the process. The byproducts of the oxidation reaction were identified, and their concentration was determined during the

Anna M. Polcaro; Simona Palmas

1997-01-01

23

Solid oxide electrochemical reactor science.  

SciTech Connect

Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

2010-09-01

24

Electrochemical Oxidation of 8-Oxoguanine  

Microsoft Academic Search

Abstract Electrochemical oxidation of DNA can occur at each of the four bases and guanine is the one that can suffer the easiest oxidative damage. The occurrence of the guanine oxidation product, 8-oxoguanine, as a consequence of DNA damage caused by DNA oxidation causes important mutagenic,lesions and hence it is very important to develop reliable methods,for its quantification. Electrochemical study

A. M. Oliveira Brett; J. A. P. Piedade; S. H. P. Serrano

2000-01-01

25

Mineralization of clofibric acid by electrochemical advanced oxidation processes using a boron-doped diamond anode and Fe 2+ and UVA light as catalysts  

Microsoft Academic Search

This work shows that aqueous solutions of clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid), the bioactive metabolite of various lipid-regulating drugs, up to saturation at pH 3.0 are efficiently and completely degraded by electrochemical advanced oxidation processes such as electro-Fenton and photoelectro-Fenton with Fe2+ and UVA light as catalysts using an undivided electrolytic cell with a boron-doped diamond (BDD) anode and an O2-diffusion

Ignasi Sirés; Francesc Centellas; José Antonio Garrido; Rosa María Rodríguez; Conchita Arias; Pere-Lluís Cabot; Enric Brillas

2007-01-01

26

ELECTROCHEMICAL METALLIZING OF ADVANCED MATERIALS  

Microsoft Academic Search

Electrochemical metallizing provides sound metallurgical coatings for maintenance and production applications. The technique involves tankless electroplating, using a brush-on procedure.Maintenance applications involve resizing, restoring, rebuilding or resurfacing worn, damaged, corroded, eroded or overmachined metal components. This paper deals with special production applications. The title may be a misnomer, since the paper deals with advanced materials, but also covers special unique

M. Rubinstein

1989-01-01

27

Electrochemical oxidation of chlorinated phenols  

Microsoft Academic Search

Electrochemical oxidation has been proposed as a remediation method for chlorinated phenols but is hampered by anode fouling. In this work the authors explore the mechanism of anode fouling by chlorinated phenols, compare structure vs reactivity for phenols differing in the extent of chlorination, and relate the efficiency of oxidation to the mechanism of oxidation at different electrode types. Linear

James D. Rodgers; Wojciech Jedral; Nigel J. Bunce

1999-01-01

28

Direct electrochemical oxidation of polyacrylates.  

PubMed

A promising elimination treatment of non-biodegradable organic pollutants is the direct electro-oxidation. In this work has been proposed the electrochemical elimination of polyacrylates by using boron-doped diamond (BDD) as anodic material. The complete elimination of organic contaminants has been obtained and this is the first case of successful electrochemical treatment of polymeric and bio-refractory species. The tests of the electrochemical oxidation have been conducted at constant current conditions and a complete elimination of organic species has been reached. The decrease of the COD value with time follows the behaviour of an ideal anode as in the case of low molecular organic compounds. PMID:12489259

Bellagamba, Riccardo; Comninellis, Christos; Vatistas, Nicolaos

2002-10-01

29

Electrochemical oxidation of wastewater - opportunities and drawbacks.  

PubMed

Electrochemical oxidation by means of boron-doped diamond (BDD) anodes generates a very efficient oxidizing environment by forming hydroxyl radicals, providing effective water purification for elimination of persistent pollutants. In this project the degradation rates of organic and inorganic substances are investigated. Experiments were performed in laboratory and pilot scale with synthetic and industrial wastewaters. Performance parameters were evaluated in terms of total organic carbon/chemical oxygen demand (COD) removal, specific energy consumption and current efficiency. The integration of this advanced oxidation technology combined with conventional technology was then applied in a wastewater treatment concept of landfill leachate. The raw leachate with a low biochemical oxygen demand/COD ratio was electrochemically oxidized to prepare the purified leachate for discharge into a sewage system or a receiving water body. The cost estimation regarding operation and capital costs addresses the economics for the treatment of heavily polluted effluents. PMID:24037171

Woisetschläger, D; Humpl, B; Koncar, M; Siebenhofer, M

2013-01-01

30

Hazardous Organic Waste Destruction by Electrochemical Oxidation.  

National Technical Information Service (NTIS)

For these reasons, a project was funded to investigate an electrochemical method for oxidation of hazardous and mixed wastes. Electrochemical oxidation (ECO) has been successfully applied for destruction of very dilute solutions of chlorinated solvents in...

P. M. Molton A. G. Fassbender S. A. Nelson J. K. Cleveland

1988-01-01

31

Electrochemical oxidation of organic waste  

SciTech Connect

Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids.

Almon, A.C.; Buchanan, B.R.

1990-01-01

32

Electrochemical oxidation of organic waste  

SciTech Connect

Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids.

Almon, A.C.; Buchanan, B.R.

1990-12-31

33

Electrochemical oxidation of organic materials.  

National Technical Information Service (NTIS)

This invention is a method and apparatus for the direct oxidation of organic materials, especially organic wastes, in an electrochemical cell. It fulfills the need for a simple, cost-effective way for generators of small quantities of waste to deal with t...

A. C. Almon

1991-01-01

34

Mineralization of salicylic acid in acidic aqueous medium by electrochemical advanced oxidation processes using platinum and boron-doped diamond as anode and cathodically generated hydrogen peroxide.  

PubMed

Solutions containing 164 mg L(-1) salicylic acid of pH 3.0 have been degraded by electrochemical advanced oxidation processes such as anodic oxidation, anodic oxidation with electrogenerated H(2)O(2), electro-Fenton, photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Their oxidation power has been comparatively studied in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and a graphite or O(2)-diffusion cathode. In the three latter procedures, 0.5mM Fe(2+) is added to the solution to form hydroxyl radical (()OH) from Fenton's reaction between Fe(2+) and H(2)O(2) generated at the O(2)-diffusion cathode. Total mineralization is attained for all methods with BDD and for photoelectro-Fenton and solar photoelectro-Fenton with Pt. The poor decontamination achieved in anodic oxidation and electro-Fenton with Pt is explained by the slow removal of most pollutants by ()OH formed from water oxidation at the Pt anode in comparison to their quick destruction with ()OH produced at BDD. ()OH generated from Fenton's reaction oxidizes rapidly all aromatic pollutants, but it cannot destroy final Fe(III)-oxalate complexes. Solar photoelectro-Fenton treatments always yield quicker degradation rate due to the very fast photodecarboxylation of these complexes by UVA irradiation supplied by solar light. The effect of current density on the degradation rate, efficiency and energy cost of all methods is examined. The salicylic acid decay always follows a pseudo-first-order kinetics. 2,3-Dihydroxybenzoic, 2,5-dihydroxybenzoic, 2,6-dihydroxybenzoic, alpha-ketoglutaric, glycolic, glyoxylic, maleic, fumaric, malic, tartronic and oxalic acids are detected as oxidation products. A general reaction sequence for salicylic acid mineralization considering all these intermediates is proposed. PMID:17692891

Guinea, Elena; Arias, Conchita; Cabot, Pere Lluís; Garrido, José Antonio; Rodríguez, Rosa María; Centellas, Francesc; Brillas, Enric

2007-08-01

35

Electrochemical oxidation for landfill leachate treatment  

Microsoft Academic Search

This paper aims at providing an overview of electrochemical oxidation processes used for treatment of landfill leachate. The typical characteristics of landfill leachate are briefly reviewed, and the reactor designs used for electro-oxidation of leachate are summarized. Electrochemical oxidation can significantly reduce concentrations of organic contaminants, ammonia, and color in leachate. Pretreatment methods, anode materials, pH, current density, chloride concentration,

Yang Deng; James D. Englehardt

2007-01-01

36

Surface characterization of electrochemically oxidized carbon fibers  

Microsoft Academic Search

High strength PAN-based carbon fibers were continuously electrochemically oxidized by applying current to the fibers serving as an anode in 1% wt aqueous KNO3. Progressive fiber weight loss occurred with increasing extents of electrochemical oxidation. XPS studies (C 1s and O 1s) indicated that the oxygen\\/carbon atomic ratio rose rapidly to 0.24 as the extent of electrochemical oxidation was increased

Z. R. Yue; W. Jiang; L. Wang; S. D. Gardner; C PITTMANJR

1999-01-01

37

Enhanced electrochemical oxidation of anionic surfactants  

Microsoft Academic Search

The surfactant wastewater treatment by electro?chemical oxidation with or without peroxide hydrogen was investigated. The two anionic surfactants studied here were alkylbenzene sulfonate (ABS) and linear alkylbenzene sulfonate (LAS), both of them being widely used in the household and industrial detergents. Experiments were conducted to examine the effects of pH, electrolyte concentration, time of electrochemical oxidation, power input and amount

Homg G. Leu; Sheng H. Lin; Tze M. Lin

1998-01-01

38

Costs of the electrochemical oxidation of wastewaters: A comparison with ozonation and Fenton oxidation processes  

Microsoft Academic Search

In the work described here the technical and economic feasibilities of three Advanced Oxidation Processes (AOPs) have been studied: Conductive-Diamond Electrochemical Oxidation (CDEO), Ozonation and Fenton oxidation. The comparison was made by assessing the three technologies with synthetic wastewaters polluted with different types of organic compounds and also with actual wastes (from olive oil mills and from a fine-chemical manufacturing

Pablo Cañizares; Rubén Paz; Cristina Sáez; Manuel A. Rodrigo

2009-01-01

39

Study of the toxicity of diuron and its metabolites formed in aqueous medium during application of the electrochemical advanced oxidation process "electro-Fenton".  

PubMed

Diuron (N'-[3,4-dichlorophenyl]-N,N-dimethylurea) is a herbicide belonging to the phenylurea family, widely used to destroy weeds on uncultivated surfaces. Because of its toxicity for aquatic organisms and suspicion of being carcinogenic for humans, diuron is the object of growing environmental concern. Therefore, we have developed the electro-Fenton method, an electrochemical advanced oxidation process (EAOP), to degrade diuron in aqueous medium, and we have studied the evolution of the toxicity of treated solution during the process. Indeed, the EAOPs catalytically generate hydroxyl radicals that oxidize the persistent organic pollutants, and can ultimately destroy and mineralize them. But, sometimes, relatively toxic organic metabolites are formed during the oxidation reaction. In this work, the evolution of toxicity of diuron aqueous solutions was studied at different initial concentrations, during treatment by the electro-Fenton method. Samples were collected at various electrolysis times and mineralization degrees during the treatment. The toxicity of the samples was measured using the bacteria Vibrio fischeri (Microtox) and the green alga Scenedesmus obliquus. Our results demonstrated that the toxicity of diuron aqueous solutions (concentrations=3.0-27.6 mg L(-1)) varied considerably with time. The formation and disappearance of several metabolites, having toxicity often stronger than that of the initial herbicide, were observed. To improve the efficiency of water decontamination, the electro-Fenton method should be applied during a time long enough (several hours) and at relatively high electrolysis current (I=250 mA) to reach a nearly complete mineralization of the herbicide in the aqueous medium. PMID:18812249

Oturan, Nihal; Trajkovska, Snezana; Oturan, Mehmet A; Couderchet, Michel; Aaron, Jean-Jacques

2008-09-21

40

Electrochemical oxidation for landfill leachate treatment  

SciTech Connect

This paper aims at providing an overview of electrochemical oxidation processes used for treatment of landfill leachate. The typical characteristics of landfill leachate are briefly reviewed, and the reactor designs used for electro-oxidation of leachate are summarized. Electrochemical oxidation can significantly reduce concentrations of organic contaminants, ammonia, and color in leachate. Pretreatment methods, anode materials, pH, current density, chloride concentration, and other additional electrolytes can considerably influence performance. Although high energy consumption and potential chlorinated organics formation may limit its application, electrochemical oxidation is a promising and powerful technology for treatment of landfill leachate.

Deng, Yang [Department of Civil, Architectural and Environmental Engineering, McArthur Building, Room 325, 1251 Memorial Dr., University of Miami, Coral Gables, FL 33146 (United States)], E-mail: dengyang7@yahoo.com; Englehardt, James D. [Department of Civil, Architectural and Environmental Engineering, McArthur Building, Room 325, 1251 Memorial Dr., University of Miami, Coral Gables, FL 33146 (United States)

2007-07-01

41

Surface properties of electrochemically oxidized carbon fibers  

Microsoft Academic Search

High-strength PAN-based carbon fibers were continuously electrochemically oxidized by applying current through the fibers which served as an anode in 1% wt. KNO3 solutions. NaOH titration showed that the quantity of acidic surface functions increased with the extent of electrochemical oxidation up to oxidation levels of 6360 Cg?1. Fibers with over 1.1 mmolg?1 of total acidic functional groups per gram

C PITTMANJR; W. Jiang; Z. R. Yue; S. Gardner; L. Wang; H. Toghiani; C. A. Leon y Leon

1999-01-01

42

Electrochemical oxidation of organic materials  

DOEpatents

This invention is a method and apparatus for the direct oxidation of organic materials, especially organic wastes, in an electrochemical cell. It fulfills the need for a simple, cost-effective way for generators of small quantities of waste to deal with that waste. It does not use an electron transfer agent, which may be a source of additional hazardous waste. The anode is made of carbon felt; the cathode is platinum; and the electrolyte is a strong oxidizer, preferably nitric acid. The potential difference is 2 to 3 volts; the current density is 0.15 to 0.25 A/cm{sup 2}. The porous barrier is a medium grade alumina frit or an ion exchange membrane. The organic materials are fed to the anode compartment; the resulting oxygen bubbling circumvents the need for stirring or circulating the waste. Many different types of waste (e.g. rubber gloves, TBP, process solutions, etc.) can be fed to the anode compartment without the need to process or store it. 3 figs. (DLC)

Almon, A.C.

1991-12-31

43

Electrochemical oxidation of azithromycin and its derivatives.  

PubMed

The electrochemical oxidation of azithromycin was investigated in order to elucidate the mechanism for possible oxidative metabolic pathways in humans. Electrochemical studies were carried out by cyclic voltammetry and preparative scale electrolysis at glassy carbon electrodes. It was found that azithromycin undergoes anodic oxidation at one or both amine groups with the rapid follow-up chemistry of intermediate radical cation. Main products of the oxidation were determined by HPLC analysis and were identified as a protonated azithromycin and products obtained by demethylation of the 3'-dimethylamino or macrolactone amino group. PMID:14623590

Mandi?, Zoran; Weitner, Zlatko; Ilijas, Marina

2003-11-24

44

DEVELOPMENT OF ELECTROCHEMICAL REDUCTION TECHNOLOGY FOR SPENT OXIDE FUELS  

SciTech Connect

The Advanced Spent Fuel Conditioning Process (ACP) has been under development at Korea Atomic Energy Research Institute (KAERI) since 1997. The concept is to convert spent oxide fuel into metallic form and to remove high heat-load fission products such as Cs and Sr from the spent fuel. The heat power, volume, and radioactivity of spent fuel can decrease by a factor of a quarter via this process. For the realization of ACP, a concept of electrochemical reduction of spent oxide fuel in Li2O-LiCl molten salt was proposed and several cold tests using fresh uranium oxides have been carried out. In this new electrochemical reduction process, electrolysis of Li2O and reduction of uranium oxide are taking place simultaneously at the cathode part of electrolysis cell. The conversion of uranium oxide to uranium metal can reach more than 99% ensuring the feasibility of this process.

Hur, Jin-Mok; Seo, Chung-Seok; Kim, Ik-Soo; Hong, Sun-Seok; Kang, Dae-Seung; Park, Seong-Won

2003-02-27

45

Dechlorination by combined electrochemical reduction and oxidation.  

PubMed

Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electrochemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol. PMID:15909345

Cong, Yan-qing; Wu, Zu-cheng; Tan, Tian-en

2005-06-01

46

Switching Atomic Friction by Electrochemical Oxidation.  

PubMed

Friction between the sliding tip of an atomic force microscope and a gold surface changes dramatically upon electrochemical oxidation of the gold surface. Atomic-scale variations of the lateral force reveal details of the friction mechanisms. Stick-slip motion with atomic periodicity on perfect Au(111) terraces exhibits extremely low friction and almost no dependence on load. Significant friction is observed only above a load threshold at which wear of the surface is initiated. In contrast, irregular stick-slip motion and a linear increase of friction with load are observed on electrochemically oxidized surfaces. The observations are discussed with reference to the amorphous structure of the oxo-hydroxide surface and atomic place exchange mechanisms upon oxidation. Reversible, fast switching between the two states of friction has been achieved in both perchloric and sulfuric acid solutions. PMID:21314153

Labuda, Aleksander; Hausen, Florian; Gosvami, Nitya Nand; Gru?tter, Peter H; Lennox, R Bruce; Bennewitz, Roland

2011-02-11

47

A high-performance flexible fibre-shaped electrochemical capacitor based on electrochemically reduced graphene oxide.  

PubMed

A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility. PMID:23183591

Li, Yingru; Sheng, Kaixuan; Yuan, Wenjing; Shi, Gaoquan

2012-11-26

48

Electrochemical Oxidation of Saturated Hydrocarbons.  

National Technical Information Service (NTIS)

A study was undertaken to define and analyze the factors controlling the catalytic activity of platinum black toward the anodic oxidation of saturated hydrocarbons. The objective was to develop a correlation between the physical characteristics of a black...

J. Giner J. M. Parry

1967-01-01

49

Electrochemical oxidation of olive oil mill wastewaters  

Microsoft Academic Search

The electrochemical oxidation of olive oil mill wastewaters over a titanium–tantalum–platinum–iridium anode was investigated. Batch experiments were conducted in a flow-through electrolytic cell with internal recycle at voltage of 5, 7 and 9V, NaCl concentrations of 1%, 2% and 4%, recirculation rates of 0.4 and 0.62L\\/s and initial chemical oxygen demand (COD) concentrations of 1475, 3060, 5180 and 6545mg\\/L. The

Marina Gotsi; Nicolas Kalogerakis; Elefteria Psillakis; Petros Samaras; Dionissios Mantzavinos

2005-01-01

50

Electrochemical Oxidation of Saturated Hydrocarbons.  

National Technical Information Service (NTIS)

The aim of this work was to correlate the activity and stability of Pt-based catalysts for C3H8 electro-oxidation, with their structural properties. There were three distinct aspects to this study: (1) preparation of the catalyst, (2) its physical charact...

S. B. Brummer J. Giner

1966-01-01

51

Electrochemical Hypothesis of Oxidative Phosphorylation.  

National Technical Information Service (NTIS)

The hypothesis of oxidative phophorylation under examination states that in certain particles the protons on the surface of a lipid react with the anions present in an aqueous phase and the neutral molecules formed pass over into the lipid layer. The dehy...

I. S. Balakhovskii

1970-01-01

52

Mineralization of Drugs in Aqueous Medium by Advanced Oxidation Processes  

Microsoft Academic Search

At present chemical (AOPs) and electrochemical (EAOPs) advanced oxidation processes with ability to destroy organic pollutants in waters are being developed. These methods are based on the production of hydroxyl radical ( •OH) as oxidant. In AOPsOH radical can be obtained from Fenton's reaction between Fe 2+ and H 2O2 added to the medium, photoreduction of Fe 3+ species or

José Antonio Garrido; Enric Brillas; Pere Lluís Cabot; Francesc Centellas; Conchita Arias; Rosa María Rodríguez

2007-01-01

53

Indirect oxidation effect in electrochemical oxidation treatment of landfill leachate  

Microsoft Academic Search

Treatment of a low BODCOD ratio landfill leachate was conducted by means of electrochemical oxidation process in this investigation. Under the operating conditions of 15 A\\/dm2 current density and 7500 mg\\/l additional chloride concentration, 92% of the COD in the landfall leachate was removed after electrolysis for 240 min with a ternary Sn?Pd?Ru oxide-coated titanium (SPR) anode. At the same

Li-Choung Chiang; Juu-En Chang; Ten-Chin Wen

1995-01-01

54

Treatment of aqueous wastes contaminated with Congo Red dye by electrochemical oxidation and ozonation processes  

Microsoft Academic Search

Synthetic aqueous wastes polluted with Congo Red (CR) have been treated by two advanced oxidation processes: electrochemical oxidation on boron doped diamond anodes (BDD-EO) and ozonation under alkaline conditions. For same concentrations, galvanostatic electrolyses have led to total COD and TOC removals but ozonation process can reach only 85% and 81% of COD and TOC removals, respectively. UV–vis qualitative analyses

Mohammed Faouzi Elahmadi; Nasr Bensalah; Abdellatif Gadri

2009-01-01

55

Chemical and Electrochemical Behavior of Carbonate Melts Containing Silicon Oxide  

Microsoft Academic Search

The optimal conditions of electrochemical synthesis of silicon carbide in carbonate melts containing silicon oxide were determined on the basis of thermodynamic calculations and data of cyclic voltammetry.

S. V. Devyatkin; A. D. Pisanenko; V. I. Shapoval

2002-01-01

56

Solid oxide electrochemical cell fabrication process  

DOEpatents

A method to form an electrochemical cell (12) is characterized by the steps of thermal spraying stabilized zirconia over a doped lanthanum manganite air electrode tube (14) to provide an electrolyte layer (15), coating conductive particles over the electrolyte, pressurizing the outside of the electrolyte layer, feeding halide vapors of yttrium and zirconium to the outside of the electrolyte layer and feeding a source of oxygen to the inside of the electrolyte layer, heating to cause oxygen reaction with the halide vapors to close electrolyte pores if there are any and to form a metal oxide coating on and between the particles and provide a fuel electrode (16).

Dollard, Walter J. (Churchill Borough, PA); Folser, George R. (Lower Burrell, PA); Pal, Uday B. (Cambridge, MA); Singhal, Subhash C. (Murrysville, PA)

1992-01-01

57

Degradation of pharmaceutical beta-blockers by electrochemical advanced oxidation processes using a flow plant with a solar compound parabolic collector.  

PubMed

The degradation of the beta-blockers atenolol, metoprolol tartrate and propranolol hydrochloride was studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Solutions of 10 L of 100 mg L?¹ of total organic carbon of each drug in 0.1 M Na?SO? with 0.5 mM Fe²? of pH 3.0 were treated in a recirculation flow plant with an electrochemical reactor coupled with a solar compound parabolic collector. Single Pt/carbon felt (CF) and boron-doped diamond (BDD)/air-diffusion electrode (ADE) cells and combined Pt/ADE-Pt/CF and BDD/ADE-Pt/CF cells were used. SPEF treatments were more potent with the latter cell, yielding 95-97% mineralization with 100% of maximum current efficiency and energy consumptions of about 0.250 kWh g TOC?¹. However, the Pt/ADE-Pt/CF cell gave much lower energy consumptions of about 0.080 kWh g TOC?¹ with slightly lower mineralization of 88-93%, then being more useful for its possible application at industrial level. The EF method led to a poorer mineralization and was more potent using the combined cells by the additional production of hydroxyl radicals (•OH) from Fenton's reaction from the fast Fe²? regeneration at the CF cathode. Organics were also more rapidly destroyed at BDD than at Pt anode. The decay kinetics of beta-blockers always followed a pseudo first-order reaction, although in SPEF, it was accelerated by the additional production of •OH from the action of UV light of solar irradiation. Aromatic intermediates were also destroyed by hydroxyl radicals. Ultimate carboxylic acids like oxalic and oxamic remained in the treated solutions by EF, but their Fe(III) complexes were photolyzed by solar irradiation in SPEF, thus explaining its higher oxidation power. NO?? was the predominant inorganic ion lost in EF, whereas the SPEF process favored the production of NH?? ion and volatile N-derivatives. PMID:21693380

Isarain-Chávez, Eloy; Rodríguez, Rosa María; Cabot, Pere Lluís; Centellas, Francesc; Arias, Conchita; Garrido, José Antonio; Brillas, Enric

2011-05-31

58

Electrochemical lithium intercalation in nanosized manganese oxides  

NASA Astrophysics Data System (ADS)

X-ray amorphous manganese oxides were prepared by reduction of sodium permanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition of manganese carbonate at moderate temperature (MnOx-C). TEM showed that these materials are not amorphous, but nanostructured, with a prominent spinel substructure in MnOx-C. These materials intercalate lithium with capacities up to 200 mAh/g at first cycle (potential window 1.8 4.3 V) and 175 mAh/g at 100th cycle. Best performances for MnOx-C are obtained with cobalt doping. Potential electrochemical spectroscopy shows that the initial discharge induces a 2-phase transformation in MnOx-C phases, but not in MnOx-I ones. EXAFS and XANES confirm the participation of manganese in the redox process, with variations in local structure much smaller than in known long-range crystallized manganese oxides. X-ray absorption spectroscopy also shows that cobalt in MnOx-C is divalent and does not participate in the electrochemical reaction.

Strobel, P.; Darie, C.; Thiéry, F.; Ibarra-Palos, A.; Bacia, M.; Proux, O.; Soupart, J. B.

2006-05-01

59

Electrochemical oxidation of phenol using graphite anodes  

SciTech Connect

The effects of current and pH on the electrochemical oxidation of phenol on graphite electrodes is investigated in this study. There was no sign of deterioration of the graphite bed after 5 months of operation. Phenol removal efficiency was a function of the current applied and was around 70% at a current of 2.2 A. The increase of phenol removal efficiency with current is attributed to the increase of ionic transport which increases the rate of electrode reactions responsible for the removal process. The percentage of complete oxidation of phenol increases with current, with a maximum value of about 50%. However, at pH 0.2 it is slightly higher than that at pH 0.5 at all currents. The phenol removal rate increases with increases of current and pH. While the current (CO{sub 2}) efficiency reaches a maximum value in the current range of 1.0--1.2 A, it increases with an increase of acid concentration. The findings of this study have important implications: while anodic oxidation of phenol on graphite can achieve acceptable removal of phenol, the extent of oxidation should not be overlooked.

Awad, Y.M. [Arab Centre for Engineering Studies, Abu-Dhabi (United Arab Emirates); Abuzaid, N.S. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Research Inst.

1999-02-01

60

Advanced materials and electrochemical processes in high-temperature solid electrolytes  

SciTech Connect

Fuel cells for the direct conversion of fossil fuels to electric energy necessitates the use of high-temperature solid electrodes. This study has included: (1) determination of electrical transport, thermal and electrical properties to illucidate the effects of microstructure, phase equilibria, oxygen partial pressure, additives, synthesis and fabrication on these properties; (2) investigation of synthesis and fabrication of advanced oxide materials, such as La{sub 0.9}Sn{sub 0.1}MnO{sub 3}; and (3) application of new analytical techniques using complex impedance coupled with conventional electrochemical methods to study the electrochemical processes and behavior of materials for solid oxide fuel cells and other high-temperature electrolyte electrochemical process. 15 refs., 10 figs., 2 tabs. (BM)

Bates, J.L.; Chick, L.A.; Youngblood, G.E.; Weber, W.J.

1990-10-01

61

Interface evolution during electrochemical oxidation-dissolution  

NASA Astrophysics Data System (ADS)

We present results from an experimental study on the roughening of Al thin film during electrochemical oxidation reduction. The surface reaction occurred in two stages. Anodic alumina forms during oxidation of aluminum followed by immediate dissolution of alumina. The surface image using AFM showed randomly oriented grains with lateral feature size ˜280 nm at early stage (30 s) of oxidation-dissolution (OD). As farther dissolution of alumina (90 s) progressed, oriented rectangular grains were observed with lateral feature size ˜400 nm, indicating a disordered to ordered transition at the surface. The roughness exponent at the earlier stage found to be 0.44 ± 0.02, consistent with nonlinear KPZ equation. However, for the later case, roughness exponent increased to 0.84 ± 0.03, which is close to the value derived in continuum model. The value of dissolution exponent (growth exponent) ? found to be 0.47 ± 0.1. These values are slightly different from the theoretical values but they are consistent with the theoretical models within the experimental error. Shadow instability found to be a dominant feature in this experiment and contributed to the discrepancy. Interface instabilities are discussed in terms of local and non-local effects.

Aurongzeb, Deeder

2005-11-01

62

Insertion reactions in advanced electrochemical energy storage  

Microsoft Academic Search

A rechargeable electrochemical energy storage system employing an organic solvent-based electrolyte will be introduced: the lithium-ion cell. The electrode reactions base on Li+-insertion\\/-removal which ensure high rechargeability. The system possesses an operating voltage of -3.5 V and a high energy density. From a thermodynamic viewpoint such a cell is impossible because the used organic electrolyte is in contact with two

Jiirgen Otto Besenhard; Martin Winter

1998-01-01

63

Advancement in electrochemical micro-machining  

Microsoft Academic Search

Electrochemical micro-machining (EMM) appears to be very promising as a future micro-machining technique, since in many areas of applications it offers several advantages, which include higher machining rate, better precision and control, and a wide range of materials that can be machined. In this paper, a review is presented on current research, development and industrial practice in micro-ECM. This paper

B. Bhattacharyya; J. Munda; M. Malapati

2004-01-01

64

Degradation of caffeine by conductive diamond electrochemical oxidation.  

PubMed

The use of Conductive-Diamond Electrochemical Oxidation (CDEO) and Sonoelectrochemical Oxidation (CDSEO) has been evaluated for the removal of caffeine of wastewater. Effects of initial concentration, current density and supporting electrolyte on the process efficiency are assessed. Results show that caffeine is very efficiently removed with CDEO and that depletion of caffeine has two stages depending on its concentration. At low concentrations, opposite to what it is expected in a mass-transfer controlled process, the efficiency increases with current density very significantly, suggesting a very important role of mediated oxidation processes on the removal of caffeine. In addition, the removal of caffeine is faster than TOC, indicating the formation of reaction intermediates. The number and relative abundance of them depend on the operating conditions and supporting electrolyte used. In chloride media, removal of caffeine is faster and more efficiently, although the occurrence of more intermediates takes place. CDSEO does not increase the efficiency of caffeine removal, but it affects to the formation of intermediates. A detailed characterization of intermediates by liquid chromatography time-of-flight mass spectrometry seems to indicate that the degradation of caffeine by CDEO follows an oxidation pathway similar to mechanism proposed by other advanced oxidation processes. PMID:23769468

Indermuhle, Chloe; Martín de Vidales, Maria J; Sáez, Cristina; Robles, José; Cañizares, Pablo; García-Reyes, Juan F; Molina-Díaz, Antonio; Comninellis, Christos; Rodrigo, Manuel A

2013-06-13

65

Advanced Photochemical Oxidation Processes. Handbook.  

National Technical Information Service (NTIS)

This handbook discusses the applicability of advanced photochemical oxidation (APO) technologies for treatment of contaminated water, air, and solids (soil, sediment, and ash). The primary purpose of this handbook is to summarize commercial-scale APO syst...

K. Topudurtir S. Tay E. Monschein

1998-01-01

66

Degradation of pharmaceutical beta-blockers by electrochemical advanced oxidation processes using a flow plant with a solar compound parabolic collector  

Microsoft Academic Search

The degradation of the beta-blockers atenolol, metoprolol tartrate and propranolol hydrochloride was studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Solutions of 10 L of 100 mg L?1 of total organic carbon of each drug in 0.1 M Na2SO4 with 0.5 mM Fe2+ of pH 3.0 were treated in a recirculation flow plant with an electrochemical reactor coupled with a solar compound parabolic collector. Single

Eloy Isarain-Chávez; Rosa María Rodríguez; Pere Lluís Cabot; Francesc Centellas; Conchita Arias; José Antonio Garrido; Enric Brillas

2011-01-01

67

Preparation of the electrochemically formed spinel-lithium manganese oxides  

Microsoft Academic Search

Electrochemically formed spinel-lithium manganese oxides were synthesized from manganese hydroxides prepared by a cathodic electrochemical precipitation from various concentrations of manganese nitrate solutions. Two types of manganese hydroxides were formed from diluted and concentrated Mn(NO3)2 aqueous solutions. Uniform and equi-sized disk shaped Mn(OH)2 crystals of 0.2–5?m in diameter were obtained on a Pt substrate after the electrochemical precipitation from lower

Katsumi Katakura; Kohei Wada; Yoshiyuki Kajiki; Akiko Yamamoto; Zempachi Ogumi

2009-01-01

68

Electrochemical oxidation of textile wastewater and its reuse  

Microsoft Academic Search

It is attempted in the present investigation to treat organic pollutant present in the textile effluent using an electrochemical treatment technique. Experiments are carried out in a batch electrochemical cell covering wide range in operating conditions. Due to the strong oxidizing potential of the chemicals produced, the effluent COD is reduced substantially in this treatment technique. The influence of effluent

N. Mohan; N. Balasubramanian; C. Ahmed Basha

2007-01-01

69

Oxalic acid mineralization by electrochemical oxidation processes.  

PubMed

In this study, two electrochemical oxidation processes were utilized to mineralize oxalic acid which was a major intermediate compound in the oxidation of phenols and other aromatic compounds. The anode rod and cathode net were made of a titanium coated with RuO(2)/IrO(2) (Ti-DSA) and stainless steel (S.S. net, SUS304), respectively. First, the Fered-Fenton process, which used H(2)O(2) and Fe(2+) as additive reagents, achieved 85% of TOC removal. It proceeded with ligand-to-metal charge-transfer (LMCT), which was evidenced by the accumulation of metallic foil on the selected cathode. However, in the absence of H(2)O(2)/Fe(2+), it showed a higher TOC removal efficiency while using Cl(-) only as an additive reagent due to the formation of hypochlorite on the anode. It was also found that the mineralization of oxalic acid by electrolysis generated hypochlorite better than the dosage of commercial hypochlorite without electricity. Also, pH value was a major factor that affected the mineralization efficiency of the oxalic acid due to the chlorine chemistry. 99% TOC removal could be obtained by Cl(-) electrolysis in an acidic environment. PMID:21320749

Huang, Yao-Hui; Shih, Yu-Jen; Liu, Cheng-Hong

2011-01-28

70

Recent advances in microdevices for electrochemical energy conversion and storage  

Microsoft Academic Search

SUMMARY The application of silicon microfabrication technologies to electrochemical devices allows reduction of overall device package to potentially increase volumetric power densities. This review first focuses on some exciting developments in microfuel cells, in particular, solid oxide fuel cells (SOFCs) and proton exchange membrane fuel cells (PEMFCs). The emphasis is given to innovative 2D processing methods, novel 2D architectures of

Gerardo Jose; Hyun Jin In; Ethan Crumlin; George Barbastathis; Yang Shao-Horn

2007-01-01

71

Advanced oxidation processes for the treatment of wastes polluted with azoic dyes  

Microsoft Academic Search

In this work, synthetic wastes polluted with azoic dyes have been treated with conductive-diamond electrochemical oxidation, Fenton oxidation and ozonation. Eriochrome black T (EBT), methyl orange (MO) and congo red (CR) were selected as model pollutants. Although the three technologies are classified as advanced oxidation processes and, consequently hydroxyl radicals are assumed to be involved in their oxidation mechanism, the

M. Faouzi; P. Cañizares; A. Gadri; J. Lobato; B. Nasr; R. Paz; M. A. Rodrigo; C. Saez

2006-01-01

72

Advanced electrochemical methods for characterizing the performance of organic coatings  

NASA Astrophysics Data System (ADS)

Advanced electrochemical techniques such as electrochemical impedance spectroscopy (EIS), electrochemical noise method (ENM) and coulometry as tools to study and extract information about the coating system is the focus of this thesis. This thesis explored three areas of research. In all the three research areas, advanced electrochemical techniques were used to extract information and understand the coating system. The first area was to use EIS and coulometric technique for extracting information using AC-DC-AC method. It was examined whether the total charge passing through the coating during the DC polarization step of AC-DC-AC determines coating failure. An almost constant total amount of charge transfer was required by the coating before it failed and was independent of the applied DC polarization. The second area focused in this thesis was to investigate if embedded sensors in coatings are sensitive enough to monitor changes in environmental conditions and to locate defects in coatings by electrochemical means. Influence of topcoat on embedded sensor performance was also studied. It was observed that the embedded sensors can distinguish varying environmental conditions and locate defects in coatings. Topcoat could influence measurements made using embedded sensors and the choice of topcoat could be very important in the successful use of embedded sensors. The third area of research of this thesis work was to examine systematically polymer-structure coating property relationships using electrochemical impedance spectroscopy. It was observed that the polymer modifications could alter the electrochemical properties of the coating films. Moreover, it was also observed that by cyclic wet-dry capacitance measurement using aqueous electrolyte and ionic liquid, ranking of the stability of organic polymer films could be performed.

Upadhyay, Vinod

73

Mediated and non-mediated electrochemical oxidation of isopropanol  

NASA Astrophysics Data System (ADS)

Kinetic studies of the electrochemical generation of Ag(II) and Co(III) ions and the catalytic oxidation of isopropanol in acidic media are presented. Its mediated and non-mediated electrooxidation up to carbon dioxide is considered.

Sequeira, C. A. C.; Santos, D. M. F.; Brito, P. S. D.

2006-06-01

74

ADVANCED OXIDATION PROCESS  

SciTech Connect

The removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from automotive fuels is an integral component in the development of cleaner burning and more efficient automobile engines. Oxidative desulfurization (ODS) wherein the dibenzothiophene derivative is converted to its corresponding sulfoxide and sulfone is an attractive approach to sulfur removal because the oxidized species are easily extracted or precipitated and filtered from the hydrocarbon phase. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) catalytically convert dibenzothiophene and its derivatives rapidly and effectively at moderate temperatures (50-60 C) and ambient pressure to the corresponding sulfoxides and sulfones. The oxidation process can be performed in both aqueous systems containing alcohols such as methanol, ethanol, or t-butanol, and in a two-phase hydrocarbon/aqueous system containing tert-butanol or acetonitrile. In the biphasic system, essentially complete conversion of the DBT to its oxidized products can be achieved using slightly longer reaction times than in homogeneous solution. Among the key features of the technology are the mild reaction conditions, the very high selectivity where no over oxidation of the sulfur compounds occurs, the near stoichiometric use of hydrogen peroxide, the apparent lack of degradation of sensitive fuel components, and the ease of separation of oxidized products.

Dr. Colin P. Horwitz; Dr. Terrence J. Collins

2003-11-04

75

Oxide modified air electrode surface for high temperature electrochemical cells  

DOEpatents

An electrochemical cell is made having a porous cermet electrode (16) and a porous lanthanum manganite electrode (14), with solid oxide electrolyte (15) between them, where the lanthanum manganite surface next to the electrolyte contains a thin discontinuous layer of high surface area cerium oxide and/or praseodymium oxide, preferably as discrete particles (30) in contact with the air electrode and electrolyte.

Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Churchill Boro, Allegheny County, PA)

1992-01-01

76

Destruction of cyanide in aqueous waste by electrochemical oxidation.  

PubMed

A laboratory study was carried out by electrochemical oxidation to destroy cyanide in aqueous waste. The electrode used in this study was a triple oxide coated titanium based mesh type anode and a carbon cathode. Direct and indirect methods were both carried out at alkaline conditions and indirect oxidation method in the presence of chloride was found to be more efficient. PMID:14672374

Priya, Nisha; Palanivelu, Kandasamy

77

Adsorption of precious metal ions onto electrochemically oxidized carbon fibers  

Microsoft Academic Search

Electrochemically oxidized carbon fibers (ECF) adsorbed a prodigious amount of Ag+ in contrast to oxygen plasma and nitric acid treated carbon fibers. The amount of adsorbed Ag+ reached 3700 ?mol\\/g after 5652 C\\/g of electrochemical oxidation. This value approaches the 4050 ?mol\\/g of Ag+ which adsorbed onto steam-activated Kenaf-based carbon (with a surface area of 1284 m2\\/g determined by N2\\/BET)

Z. R. Yue; W. Jiang; L. Wang; H. Toghiani; S. D. Gardner; C. U. Pittman

1999-01-01

78

pH sensor properties of electrochemically grown iridium oxide  

Microsoft Academic Search

The open-circuit potential of an electrochemically grown iridium oxide film is measured and shows a pH sensitivity between ?60 and ?80 mV\\/pH. This sensitivity is found to depend on the state of oxidation of the iridium oxide film; for a higher state of oxidation (or more of the oxide in the high valence state), the sensitivity is also higher. This

W. Olthuis; M. A. M. Robben; P. Bergveld; M. Bos; Linden van der W. E

1990-01-01

79

Electrochemical water oxidation with carbon-grafted iridium complexes.  

PubMed

Hydrogen production from water splitting provides a potential solution to storing harvested solar energy in chemical fuels, but this process requires active and robust catalysts that can oxidize water to provide a source of electrons for proton reduction. Here we report the direct, covalent grafting of molecular Ir complexes onto carbon electrodes, with up to a monolayer coverage. Carbon-grafted Ir complexes electrochemically oxidize water with a turnover frequency of up to 3.3 s(-1) and a turnover number of 644 during the first hour. Electrochemical water oxidation with grafted catalysts gave enhanced rates and stability compared to chemically driven water oxidation with the corresponding molecular catalysts. This strategy provides a way to systematically evaluate catalysts under tunable conditions, potentially providing new insights into electrochemical water oxidation processes and water oxidation catalyst design. PMID:22292527

deKrafft, Kathryn E; Wang, Cheng; Xie, Zhigang; Su, Xin; Hinds, Bruce J; Lin, Wenbin

2012-02-06

80

ADVANCED OXIDATION PROCESS  

SciTech Connect

The design of new, high efficiency and cleaner burning engines is strongly coupled with the removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from fuels. Oxidative desulfurization (ODS) wherein these dibenzothiophene derivatives are oxidized to their corresponding sulfoxides and sulfones is an approach that has gained significant attention. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) convert in a catalytic process dibenzothiophene and its derivatives to the corresponding sulfoxides and sulfones rapidly at moderate temperatures (60 C) and ambient pressure. The reaction can be performed in both an aqueous system containing an alcohol (methanol, ethanol, or t-butanol) to solubilize the DBT and in a two-phase hydrocarbon/aqueous system where the alcohol is present in both phases and facilitates the oxidation. Under a consistent set of conditions using the FeBF{sub 2} TAML activator, the degree of conversion was found to be t-butanol > methanol > ethanol. In the cases of methanol and ethanol, both the sulfoxide and sulfone were observed while for t-butanol only the sulfone was detected. In the two-phase system, the alcohol may function as an inverse phase transfer agent. The oxidation was carried out using two different TAML activators. In homogeneous solution, approximately 90% oxidation of the DBT could be achieved using the prototype TAML activator, FeB*, by sonicating the solution at near room temperature. In bi-phasic systems conversions as high as 50% were achieved using the FeB* TAML activator and hydrogen peroxide at 100 C. The sonication method yielded only {approx}6% conversion but this may have been due to mixing.

Colin P. Horwitz; Terrence J. Collins

2003-10-22

81

Oxidation of enrofloxacin with conductive-diamond electrochemical oxidation, ozonation and Fenton oxidation. A comparison  

Microsoft Academic Search

The treatment of enrofloxacin synthetic wastewaters using conductive-diamond electrochemical oxidation (CDEO), ozonation and Fenton oxidation has been studied. Results show that the three technologies can reduce the organic content of enrofloxacin synthetic wastewaters but with different performances. CDEO was the most efficient technology in terms of mineralization but not on COD removal, which was more efficiently achieved by ozonation. This

Elena Guinea; Enric Brillas; Francesc Centellas; Pablo Cañizares; Manuel A. Rodrigo; Cristina Sáez

2009-01-01

82

Costs of the electrochemical oxidation of wastewaters: a comparison with ozonation and Fenton oxidation processes.  

PubMed

In the work described here the technical and economic feasibilities of three Advanced Oxidation Processes (AOPs) have been studied: Conductive-Diamond Electrochemical Oxidation (CDEO), Ozonation and Fenton oxidation. The comparison was made by assessing the three technologies with synthetic wastewaters polluted with different types of organic compounds and also with actual wastes (from olive oil mills and from a fine-chemical manufacturing plant). All three technologies were able to treat the wastes, but very different results were obtained in terms of efficiency and mineralization. Only CDEO could achieve complete mineralization of the pollutants for all the wastes. However, the efficiencies were found to depend on the concentration of pollutant (mass transfer control of the oxidation rate). Results obtained in the oxidation with ozone (at pH 12) or by Fenton's reagent were found to depend on the nature of the pollutants, and significant concentrations of oxidation-refractory compounds were usually accumulated during the treatment. Within the discharge limits that all of the technologies can reach, the economic analysis shows that the operating cost of Fenton oxidation is lower than either CDEO or ozonation, although CD\\EO can compete satisfactorily with the Fenton process in the treatment of several kinds of wastes. Likewise, the investment cost for the ozonation process seems to be higher than either CDEO or Fenton oxidation, regardless of the pollutant treated. PMID:18082930

Cañizares, Pablo; Paz, Rubén; Sáez, Cristina; Rodrigo, Manuel A

2008-02-20

83

Electrochemical behavior of hydrated molybdenum oxides in rechargeable lithium batteries  

Microsoft Academic Search

Oxide-hydrates of molybdenum (OHM) are investigated as 3-volt cathode materials for rechargeable lithium batteries. These\\u000a materials with different water content showed a much better performance than that of MoO3 as cathode of the rechargeable lithium battery. We report the electrochemical characteristics of Li\\/\\/OHM batteries using\\u000a the oxides and oxide-hydrates of molybdenum which were synthesized from molybdic acid. The oxide has

B. Yebka; C. Julien; G. A. Nazri

1999-01-01

84

Electrochemical and partial oxidation of methane  

NASA Astrophysics Data System (ADS)

Hydrogen has been the most common fuel used for the fuel cell research but there remains challenging technological hurdles and storage issues with hydrogen fuel. The direct electrochemical oxidation of CH4 (a major component of natural gas) in a solid oxide fuel cell (SOFC) to generate electricity has a potential of commercialization in the area of auxiliary and portable power units and battery chargers. They offer significant advantages over an external reformer based SOFC, namely, (i) simplicity in the overall system architecture and balance of plant, (ii) more efficient and (iii) availability of constant concentration of fuel in the anode compartment of SOFC providing stability factor. The extreme operational temperature of a SOFC at 700-1000°C provides a thermodynamically favorable pathway to deposit carbon on the most commonly used Ni anode from CH4 according to the following reaction (CH4 = C + 2H2), thus deteriorating the cell performance, stability and durability. The coking problem on the anode has been a serious and challenging issue faced by the catalyst research community worldwide. This dissertation presents (i) a novel fabricated bi-metallic Cu-Ni anode by electroless plating of Cu on Ni anode demonstrating significantly reduced or negligible coke deposition on the anode for CH4 and natural gas fuel after long term exposure, (ii) a thorough microstructural examination of Ni and Cu-Ni anode exposed to H2, CH4 and natural gas after long term exposure at 750°C by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction and (iii) in situ electrochemical analysis of Ni and Cu-Ni for H2, CH4 and natural gas during long term exposure at 750°C by impedance spectroscopy. A careful investigation of variation in the microstructure and performance characteristics (voltage-current curve and impedance) of Ni and Cu-Ni anode before and after a long term exposure of CH4 and natural gas would allow us to test the validation of a negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by in situ infrared spectroscopy combined with mass spectrometry and (ii) evaluating the perfo

Singh, Rahul

85

Electrochemical interfaces and electrode processes: Electrochemical oxidation of small organisms  

NASA Astrophysics Data System (ADS)

This report summarizes research involving mechanistic studies of the oxidation of small hydrocarbons and carbon monoxide on platinum in aqueous electrolytes, transition metal oxides as electrocatalysts for O2 reduction and as supports for dispersed platinum, and transition metal complexes exhibiting high catalytic activity for O2 reduction on graphite.

Yeager, Ernest B.

1994-09-01

86

Fabrication of advanced electrochemical energy materials using sol-gel processing techniques  

Microsoft Academic Search

Advanced materials play an important role in electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. They are being used as both electrodes and electrolytes. Sol-gel processing is a versatile solution technique used in fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. The application of sol-gel processing in the fabrication of advanced electrochemical energy materials will

C. T. Chu; Jay Chu; Haixing Zheng

1995-01-01

87

Oxidation of advanced intermetallic compounds  

Microsoft Academic Search

Intermetallic compounds with low densities and high melting temperatures are prime structural material candidates for advanced heat engines. The close link between crystal structure and mechanical properties has led the search for new cubic pseudo-binary transition metal aluminides. Compositing leads the way for improved mechanical properties of refractory metal silicides. In all cases there is a strong competition for oxide

N. S. Bornstein

1993-01-01

88

Electrochemical oxidation of reverse osmosis concentrate on mixed metal oxide (MMO) titanium coated electrodes.  

PubMed

Reverse osmosis (RO) membranes have been successfully applied around the world for wastewater reuse applications. However, RO is a physical separation process, and besides the clean water stream (permeate) a reverse osmosis concentrate (ROC) is produced, usually representing 15-25% of the feed water flow and containing the organic and inorganic contaminants at higher concentrations. In this study, electrochemical oxidation was investigated for the treatment of ROC generated during the reclamation of municipal wastewater effluent. Using laboratory-scale two-compartment electrochemical systems, five electrode materials (i.e. titanium coated with IrO2-Ta2O5, RuO2-IrO2, Pt-IrO2, PbO2, and SnO2-Sb) were tested as anodes in batch mode experiments, using ROC from an advanced water treatment plant. The best oxidation performance was observed for Ti/Pt-IrO2 anodes, followed by the Ti/SnO2-Sb and Ti/PbO2 anodes. The effectiveness of the treatment appears to correlate with the formation of oxidants such as active chlorine (i.e. Cl2/HClO/ClO-). As a result, electro-generated chlorine led to the abundant formation of harmful by-products such as trihalomethanes (THMs) and haloacetic acids (HAAs), particularly at Ti/SnO2-Sb and Ti/Pt-IrO2 anodes. The highest concentration of total HAAs (i.e. 2.7 mg L(-1)) was measured for the Ti/SnO2-Sb electrode, after 0.55 Ah L(-1) of supplied specific electrical charge. Irrespective of the used material, electrochemical oxidation of ROC needs to be complemented by a polishing treatment to alleviate the release of halogenated by-products. PMID:21802107

Bagastyo, Arseto Y; Radjenovic, Jelena; Mu, Yang; Rozendal, René A; Batstone, Damien J; Rabaey, Korneel

2011-07-13

89

Electrochemical oxidation of phenol in a parallel plate reactor using ruthenium mixed metal oxide electrode  

Microsoft Academic Search

In this study, electrochemical oxidation of phenol was carried out in a parallel plate reactor using ruthenium mixed metal oxide electrode. The effects of initial pH, temperature, supporting electrolyte concentration, current density, flow rate and initial phenol concentration on the removal efficiency were investigated. Model wastewater prepared with distilled water and phenol, was recirculated to the electrochemical reactor by a

Yusuf Yavuz; A. Sava? Koparal

2006-01-01

90

Electrochemical oxidation of organic pollutants at low electrolyte concentrations  

Microsoft Academic Search

The electrochemical oxidation of organic pollutants is a promising process for substances which are recalcitrant to biological degradation. The anodic oxidation of coumaric acid, which is a biorefractory organic pollutant of olive oil manufacturing waste waters, was evaluated on a Pt–Ti electrode. The operating test conditions were compatible with direct discharge of the after-treatment effluent in natural water basins or

Guido Saracco; Lisa Solarino; Riccardo Aigotti; Vito Specchia; Mario Maja

2000-01-01

91

Electrochemical supercapacitor material based on manganese oxide: preparation and characterization  

Microsoft Academic Search

A novel class of electrochemical supercapacitor electrode material has been electrochemically synthesized from a manganese halide complex in water-containing acetonitrile electrolyte at room temperature. This material has been physically and chemically characterized by scanning electron microscopy, X-ray photoelectron microscopy (XPS), FT-Raman microscopy and cyclic voltammetry. XPS and FT-Raman characterization suggest that this material is composed of manganese oxide with a

Junhua Jiang; Anthony Kucernak

2002-01-01

92

[Research on synergy of combining electrochemical oxidation and catalytic wet oxidation].  

PubMed

A new catalytic wet oxidation fixed-bed reactor combined with three-dimensional electric-field was developed to investigate catalytic wet oxidation, electrochemical oxidation and electroassisted catalytic wet oxidation of the solution containing phenol in the presence of a catalyst Mn-Sn-Sb-3/gamma-Al2O3. Good electroassisted catalytic wet oxidation efficiency was obtained in the setup for the combination system even at mild conditions (T = 130 degrees C, po2 = 1.0 MPa) that the phenol conversion and TOC reduction were up to 94.0% and 88.4% after 27 min treatment, respectively. The result also shows that the rate constants of electroassisted catalytic wet oxidation are much higher than that of not only both catalytic wet oxidation and electrochemical oxidation process alone but also additive efficiencies of catalytic wet oxidation and electrochemical oxidation processes, which indicates an apparent synergetic effect between CWO and ECO processes. PMID:19774986

Wang, Hua; Li, Guang-Ming; Zhang, Fang; Huang, Ju-Wen

2009-07-15

93

Advanced oxidation of phenolic compounds  

Microsoft Academic Search

Phenol degradation with a UV\\/H2O2 advanced oxidation process (AOP) was studied in a completely mixed, batch photolytic reactor. The UV irradiation source was a low-pressure mercury vapor lamp that was axially centered and was immersed in the phenol solution. The effects of hydrogen peroxide dosage, initial phenol concentration, H2O2\\/phenol molar ratio, pH, and temperature have been investigated. The experimental results

R. Alnaizy; A. Akgerman

2000-01-01

94

Electrochemical oxidation of benzene to phenol.  

PubMed

Gas-phase electrochemistry: The direct hydroxylation of benzene to phenol was investigated using an electrochemical cell. The production of phenol over a VO(x) anode was found to be significant at 50?°C. The resultant current efficiency for phenol production and selectivity toward phenol reached 76.5 and 94.7?%, respectively. PMID:22144229

Lee, Byungik; Naito, Hiroto; Hibino, Takashi

2011-12-05

95

Electrochemical study of DNA damaged by oxidation stress.  

PubMed

Many compounds can interact with DNA leading to changes of DNA structure as point mutation and bases excision, which could trigger some metabolic failures, which leads to the changes in DNA structure resulting in cancer. Oxidation of nucleic acid bases belongs to the one of the mostly occurred type of DNA damaging leading to the above mentioned phenomena. The investigation of processes of DNA oxidation damage is topical and electrochemical methods include a versatile and sensitive tool for these purposes. 8-hydroxydeoxyguanosine (8-OHdG) is the most widely accepted marker of DNA damage. Oxidative damage to DNA by free radicals and exposure to ionizing radiation generate several other products within the double helix besides mentioned oxidation products of nucleic acid bases. The basic electrochemical behaviour of nucleic acids bases on various types of carbon electrodes is reviewed. Further, we address our attention on description of oxidation mechanisms and on detection of the most important products of nucleic bases oxidation. The miniaturization of detector coupled with some microfluidic devices is suggested and discussed. The main aim of this review is to report the advantages and features of the electrochemical detection of guanine oxidation product as 8-OHdG and other similarly produced molecules as markers for DNA damage. PMID:23092167

Zitka, Ondrej; Krizkova, Sona; Skalickova, Sylvie; Kopel, Pavel; Babula, Petr; Adam, Vojtech; Kizek, Rene

2013-02-01

96

Treatment of Radioactive Organic Wastes by an Electrochemical Oxidation  

SciTech Connect

A waste treatment system by using an electrochemical oxidation (MEO, Mediated Electrochemical Oxidation) was installed at KAERI (Korea Atomic Energy Research Institute) for the treatment of radioactive organic wastes, especially EDTA (Ethylene Diamine Tetraacetic Acid) generated during the decontamination activity of nuclear installations. A cerium and silver mediated electrochemical oxidation technique method has been developed as an alternative for an incineration process. An experiment to evaluate the applicability of the above two processes and to establish the conditions to operate the pilot-scale system has been carried out by changing the concentration of the catalyst and EDTA, the operational current density, the operating temperature, and the electrolyte concentration. As for the results, silver mediated oxidation was more effective in destructing the EDTA wastes than the cerium mediated oxidation process. For a constant volume of the EDTA wastes, the treatment time for the cerium-mediated oxidation was 9 hours and its conversion ratio of EDTA to water and CO{sub 2} was 90.2 % at 80 deg. C, 10 A, but the treatment time for the silver-mediated oxidation was 3 hours and its conversion ratio was 89.2 % at 30 deg. C, 10 A. (authors)

Kim, K.H.; Ryue, Y.G.; Kwak, K.K.; Hong, K.P. [Korea Atomic Energy Research Institute, P.O. BOX 105, Taejon, 305-600 (Korea, Republic of); Kim, D.H. [Hanil Nuclear Co., Ltd., Dongyoung Venturestel 301, Anyang (Korea, Republic of)

2007-07-01

97

Corrosion and electrochemical oxidation of a pyrite by Thiobacillus ferrooxidans  

SciTech Connect

The oxidation of a pure pyrite by Thiobacillus Ferrooxidans is not really a constant phenomenon; it must be considered to be more like a succession of different steps which need characterization. Electrochemical studies using a combination of a platinum electrode and a specific pyrite electrode (packed-ground-pyrite electrode) revealed four steps in the bioleaching process. Each step can be identified by the electrochemical behavior (redox potentials) of pyrite, which in turn can be related to chemical (leachate content), bacterial (growth), and physical (corrosion patterns) parameters of the leaching process. A comparison of the oxidation rates of iron and sulfur indicated the nonstoichiometric bacterial oxidation of a pure pyrite in which superficial phenomena, aqueous oxidation, and deep crystal dissolution are successively involved.

Mustin, C.; Berthelin, J. (Univ. de Nancy I, Notre-Dame-des-Pauvres (France)); Marion, P.; Donato, P. de (Environnement et Mineralurgie, Vandaeuvre-les-Nancy (France))

1992-04-01

98

Surface Morphology of Si(111) during Electrochemical Oxidation  

NASA Astrophysics Data System (ADS)

Topographical changes of hydrogen terminated Si(111) during electrochemical oxidation in a 0.2 M H_2SO4 aqueous solution have been investigated using atomic force microscopy (AFM). The hydrogen terminated surface with atomically flat terraces was prepared by dipping into a NH_4F aqueous solution. Electrochemical oxidation has been performed by a potentiostatic (constant potential) or a galvanostatic (constant current) method. AFM images show that the oxidation occured on the terraces and proceeded homogeneously. The surface became rough as the oxidation proceeded. However, step edges were still observed even after the charge of 50 mC/cm^2 was applied. Quantitative analysis of a relation between the charge and surface morphology will be discussed. the address below:

Ando, A.; Miki, K.; Sakamoto, K.; Matsumoto, K.; Morita, Y.; Tokumoto, H.

1997-03-01

99

Corrosion and Electrochemical Oxidation of a Pyrite by Thiobacillus ferrooxidans  

PubMed Central

The oxidation of a pure pyrite by Thiobacillus ferrooxidans is not really a constant phenomenon; it must be considered to be more like a succession of different steps which need characterization. Electrochemical studies using a combination of a platinum electrode and a specific pyrite electrode (packed-ground-pyrite electrode) revealed four steps in the bioleaching process. Each step can be identified by the electrochemical behavior (redox potentials) of pyrite, which in turn can be related to chemical (leachate content), bacterial (growth), and physical (corrosion patterns) parameters of the leaching process. A comparison of the oxidation rates of iron and sulfur indicated the nonstoichiometric bacterial oxidation of a pure pyrite in which superficial phenomena, aqueous oxidation, and deep crystal dissolution are successively involved. Images

Mustin, C.; Berthelin, J.; Marion, P.; de Donato, P.

1992-01-01

100

Electrochemical detection of nitric oxide using polymer modified electrodes  

Microsoft Academic Search

Electrochemical sensors based on chemical surface modification are very attractive because they combine high sensitivity of amperometry with new dimensions of selectivity and stability provided by the surface modifier. This review shows a few strategies employed to facilitate the detection, determination and monitoring of nitric oxide using polymer modified electrodes. Conducting and nonconducting polymer films and composite films are considered.

Aleksander Ciszewski; Grzegorz Milczarek

2003-01-01

101

Fractional surface termination of diamond by electrochemical oxidation.  

PubMed

The crystalline form of sp(3)-hybridized carbon, diamond, offers various electrolyte-stable surface terminations. The H-termination-selective attachment of nitrophenyl diazonium, imaged by AFM, shows that electrochemical oxidation can control the fractional hydrogen/oxygen surface termination of diamond on the nanometer scale. This is of particular interest for all applications relying on interfacial electrochemistry, especially for biointerfaces. PMID:22172282

Hoffmann, René; Obloh, Harald; Tokuda, Norio; Yang, Nianjun; Nebel, Christoph E

2011-12-19

102

Hydrous ruthenium oxide as an electrode material for electrochemical capacitors  

Microsoft Academic Search

The hydrous ruthenium oxide has been formed by a sol-gel process. The precursor was obtained by mixing aqueous solutions of RuClâ·xHâO and alkalis. The hydrous ruthenium oxide powder was obtained by annealing the precursor at low temperatures. The crystalline structure and the electrochemical properties of the powder have been studied as a function of the annealing temperature. At lower annealing

J. P. Zheng; P. J. Cygan; T. R. Jow

1995-01-01

103

High-temperature and electrochemical oxidation of transition metal silicides  

Microsoft Academic Search

High-temperature and electrochemical oxidation of transition metal silicides, which are widely used in microelectronics as\\u000a ohmic contacts and protective coatings for high-temperature alloys, are discussed in this review. The process of oxide film\\u000a formation during annealing or anodizing is extremely important for both applications of silicides. It is discussed for three\\u000a disilicides: MoSi2, WSi2, and TiSi2. It has been shown

A. D. Chirkin; V. O. Lavrenko; V. M. Talash

2009-01-01

104

Electrochemical oxidation of alcohols and carboxylic acids with diamond anodes  

Microsoft Academic Search

In this work, the conductive-diamond electrochemical oxidation of several short-chain organics (2-propanol, ethanol, butyric acid and chloroacetic acid) has been studied. The results obtained have been compared with those obtained in the oxidation of these compounds with Fenton reagent and with ozone at pH 12. Significant differences have been observed among the three technologies and also between the two ranges

P. Cañizares; R. Paz; C. Sáez; M. A. Rodrigo

2008-01-01

105

Electrochemical dissolution of Cr III and Cr IV oxides  

Microsoft Academic Search

Oxidative dissolution of Cr oxides can be easily performed using voltammetry of immobilised microparticles. A combined procedure\\u000a based on the dependence of current on time and potential (chronoamperometry with potential jumps) is suitable for the determination\\u000a of the sensitivity of the dissolution rate to electrochemical potential. Applying this procedure, it was found that the rate\\u000a determining step is preceded by

Tomáš Grygar; Petr Bezdi?ka

1998-01-01

106

Silver ion catalyzed cerium(IV) mediated electrochemical oxidation of phenol in nitric acid medium  

Microsoft Academic Search

Mediated electrochemical oxidation (MEO) is one of the sustainable processes for organic pollutant destruction and has been employed for organic mineralization reactions by many researchers. In the MEO a metal ion capable of exhibiting redox behavior is oxidized from lower oxidation state to higher oxidation state by an electrochemical cell and subsequently used as an oxidant for mineralizing the toxic

Manickam Matheswaran; Subramanian Balaji; Sang Joon Chung; Il Shik Moon

2007-01-01

107

Electrochemical oxidation of carbon fibres in aqueous solutions and analysis of the surface oxides  

Microsoft Academic Search

Carbon fibres with notably different surface oxides can be prepared by varying the electrochemical oxidation conditions. Through correlation of voltammetric analysis and mass spectroscopy, interpretation of the reduction peaks of the surface oxides on the basis of their potential and width is possible. Narrow voltammetric reduction peaks at strongly negative potential are indicative of the predominance of -COOH type groups,

A. D. Jannakoudakis; P. D. Jannakoudakis; E. Theodoridou; J. O. Besenhard

1990-01-01

108

Method of electrode fabrication for solid oxide electrochemical cells  

DOEpatents

A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used. 5 figs.

Jensen, R.R.

1990-11-20

109

Method of electrode fabrication for solid oxide electrochemical cells  

DOEpatents

A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used.

Jensen, Russell R. (Murrysville, PA)

1990-01-01

110

Treatment of aqueous wastes contaminated with Congo Red dye by electrochemical oxidation and ozonation processes.  

PubMed

Synthetic aqueous wastes polluted with Congo Red (CR) have been treated by two advanced oxidation processes: electrochemical oxidation on boron doped diamond anodes (BDD-EO) and ozonation under alkaline conditions. For same concentrations, galvanostatic electrolyses have led to total COD and TOC removals but ozonation process can reach only 85% and 81% of COD and TOC removals, respectively. UV-vis qualitative analyses have shown different behaviors of CR molecules towards ozonation and electrochemical oxidation. Rapid discoloration has been observed during ozonation, whereas color persistence till the end of galvanostatic electrolyses has been seen during BDD-EO process. It seems that the oxidation mechanisms involved in the two processes are different: simultaneous destruction of azoic groups is suggested during ozonation process but consecutive destruction of these groups is proposed during BDD-EO. However, energetic study has evidenced that BDD-EO appears more efficient and more economic than ozonation in terms of TOC removals. These results have been explained by the fact that during BDD-EO, other strong oxidants electrogenerated from the electrolyte oxidation such as persulfates and direct-oxidation of CR and its byproducts on BDD anodes complement the hydroxyl radicals mediated oxidation to accomplish the total mineralization of organics. PMID:19394762

Faouzi Elahmadi, Mohammed; Bensalah, Nasr; Gadri, Abdellatif

2009-03-11

111

Electrochemical lithium intercalation in disordered manganese oxides  

Microsoft Academic Search

Four highly disordered manganese oxides were prepared by reduction of sodium permanganate by chloride, iodide, hydrogen peroxide or oxalate in aqueous medium containing a large excess of Li+ ions, yielding hydrated oxides with Mn valence in the range 3.80–3.92. Thermogravimetric studies showed that the iodide-reduced oxide can be dehydrated to 92% at 240°C, while the other three ones retain water

A Ibarra Palos; M Anne; P Strobel

2001-01-01

112

Electrochemical Oxidation of Cu(111) Surfaces  

Microsoft Academic Search

We have investigated aqueous oxide formation on Cu(111) single crystal surface using in situ surface x-ray diffraction technique. The sample surface was prepared by electropolishing and the electrolyte used was dilute perchloric acid at pH 4.5. The oxidation of the Cu(111) electrode led to the formation of the epitaxial oxide of cubic Cu_2O structure or cuprite. Two twin epitaxial structures

Ian Robinson; Yong Chu

1998-01-01

113

Generation of statin drug metabolites through electrochemical and enzymatic oxidations.  

PubMed

The generation of key drug metabolites for the purpose of their complete structural characterization, toxicity testing, as well as to serve as standards for quantitative studies, is a critical step in the pharmaceutical discovery and development cycle. Here, we utilized electrochemistry/mass spectrometry for the detection and subsequent generation of six phase I metabolites of simvastatin and lovastatin. Both simvastatin and lovastatin are widely used for the treatment of hypercholesterolemia. There are known drug-drug interaction issues of statin therapy, and it has been suggested that the oxidative metabolites may contribute to the cholesterol-lowering effect of both statins. Of the known phase I metabolites of simvastatin and lovastatin, none are commercially available, and chemical means for the synthesis of a very few of them have been previously reported. Here, we report that electrochemical oxidation of less than 1 mg each of simvastatin and lovastatin led to the generation of three oxidative metabolites of each parent to allow complete nuclear magnetic resonance characterization of all six metabolites. The yields obtained by the electrochemical approach were also compared with incubation of parent drug with commercially available bacterial mutant CYP102A1 enzymes, and it was found that the electrochemical approach gave higher yields than the enzymatic oxidations for the generation of most of the observed oxidative metabolites in this study. PMID:23760135

Khera, Smriti; Hu, Na

2013-06-13

114

Electrochemical Oxidation of Cu(111) Surfaces  

NASA Astrophysics Data System (ADS)

We have investigated aqueous oxide formation on Cu(111) single crystal surface using in situ surface x-ray diffraction technique. The sample surface was prepared by electropolishing and the electrolyte used was dilute perchloric acid at pH 4.5. The oxidation of the Cu(111) electrode led to the formation of the epitaxial oxide of cubic Cu_2O structure or cuprite. Two twin epitaxial structures were found; for the ``aligned'' cuprite, Cu_2O(111) allel Cu(111) and Cu_2O(1bar10) parallel Cu(1bar10), and for the ``reversed'' cuprite, Cu_2O(bar1bar1bar1) allel Cu(111) and Cu_2O(bar110) parallel Cu(1bar10). At the initial stage of the oxidation, both types of oxide were observed to grow at the comparable rates up to a few monolayers. However, the growth of the aligned cuprite was remained ``frozen'' even after further oxidation, whereas the reversed cuprite was oberved to grow into a thick film. The diffraction intensities of the oxides suggest that the oxide growth start out to be highly non-uniform film under large compressive strain and gradually turn into a uniform film with less strain.

Robinson, Ian; Chu, Yong

1998-03-01

115

Solid oxide materials research accelerated electrochemical testing  

SciTech Connect

The objectives of this work were to develop methods for accelerated testing of cathode material for solid oxide fuel cells under selected operating conditions. The methods would be used to evaluate the performance of LSM cathode material.

Armstrong, T.R.; Windisch, C.; Arey, B.

1995-12-31

116

Electrochemical Oxidation of Barrier-Layer Metals.  

National Technical Information Service (NTIS)

As it is well known, The oxide films which possess rectified conductivity in electrolytes are the barrier-layer metals. They include aluminum, tantalum, niobium, zirconium and certain other metals.. Silicon and certain semi metals possess analogous proper...

I. S. Zhukova L. L. Odynets

1964-01-01

117

Electrochemical deposition of conducting ruthenium oxide films from solution  

SciTech Connect

In the last decade, ruthenium oxide, RuO /sub x/ (x less than or equal to 2), has been used extensively as the active anode electrocatalyst constituent for Cl/sub 2/ and O/sub 2/ evolution reactions, in chlorate production, and in metal electrowinning from mixed chloride-sulfate solutions. More recently, this material has been incorporated in several light-induced water electrolysis schemes and apparently possesses the ability to inhibit CdS photocorrosion by acting as a hole scavenger. The numerous applications for this catalyst material certainly warrant further studies of its electrochemical properties on a variety of substrates, e.g., semiconductors. The lack of a simple technique for controlled deposition of ruthenium oxide onto conducting substrates prompted us to investigate an electrochemical approach to this problem. We describe here a new way to electrochemically deposit conducting films of hydrated ruthenium oxide from an aqueous solution of the benzeneruthenium (II)aqua complex. The films slowly dissolve in aqueous electrolytes upon potential cycling, yet appear to be catalytic with regards to water oxidation.

Anderson, D.P.; Warren, L.F.

1984-02-01

118

Direct electrochemical reduction of graphene oxide on ionic liquid doped screen-printed electrode and its electrochemical biosensing application  

Microsoft Academic Search

A novel electrochemical biosensing platform using electrochemically reduced graphene oxide (ER-GNO) modified electrode was proposed. This modified electrode was prepared by one-step electrodeposition of the exfoliated GNO sheets onto the ionic liquid doped screen-printed electrode (IL-SPE). The resulting ER-GNO\\/IL-SPE brought new capabilities for electrochemical devices by combining the advantages of ER-GNO and disposable electrode. Two important biomolecules, nicotinamide adenine dinucleotide

Jianfeng Ping; Yixian Wang; Kai Fan; Jian Wu; Yibin Ying

2011-01-01

119

Electrochemical Synthesis of Heterocyclic Compounds II. Synthesis of Some N-Heterocycles by Intramolecular Oxidative Cyclisation  

Microsoft Academic Search

Electrochemical intramolecular and intermolecular cyclisations as well as reactions occurring with expansion or contraction of rings have been reviewed. Sometimes, electrochemical oxidative or reductive cyclisations have considerable advantages when compared with other chemical methods

M. La?an; K. Jakop?i?; V. Rogi?; Sh. Damoni; O. Rogi?; I. Tabakovi?

1974-01-01

120

Electrochemical oxidation of phenol at boron-doped diamond electrode  

Microsoft Academic Search

The electrochemical oxidation of phenol at synthetic boron-doped diamond thin film electrode (BDD) has been studied in acid media by cyclic voltammetry, chronoamperometry and bulk electrolysis. The results have shown that in the potential region of water stability (E<2.3 V vs. SHE) they can occur direct electron transfer reactions on BDD surface that results in electrode fouling due to the

J. Iniesta; P. A. Michaud; M. Panizza; G. Cerisola; A. Aldaz; Ch. Comninellis

2001-01-01

121

Electrochemical Deposition of Conductive Superhydrophobic Zinc Oxide Thin Films  

Microsoft Academic Search

A simple method of electrochemical deposition was adopted to prepare conductive hydrophobic zinc oxide (ZnO) thin films. The surface structures were characterized by sanning electron microscopy (SEM) and atomic force microscopy (AFM). Wettability studies revealed that the surface of the as-prepared thin films showed a contact angle (CA) for water of 128.3 ( 1.7°, whereas the superhydrophobic surface with a

Mei Li; Jin Zhai; Huan Liu; Yanlin Song; Lei Jiang; Daoben Zhu

2003-01-01

122

Anodic oxidation of a direct dye in an electrochemical reactor  

Microsoft Academic Search

In this work, anodic oxidation of C.I. direct blue 21 was carried out in an electrochemical reactor at a constant temperature of 20°C. The technique was found successful in removing the color of the dye from aqueous solutions containing 0.5 M sodium sulfate. Variables studied were: initial dye concentration, solution flow rate to the reactor, anode area, current density and

M. S. E. Abdo

1987-01-01

123

Alkylation of nitroaromatics with tetraalkylborate ion via electrochemical oxidation.  

PubMed

Aromatic nucleophilic substitution reaction (S(N)Ar) is one of the most thoroughly studied reactions. Alkylation of nitroaromatics with Grignard reagents via chemical oxidation of the sigma(H)-complexes is the most general method to introduce an alkyl group into a nitroaromatic compound. This approach has considerable drawbacks, especially when more than one nitro group are present in the aromatic ring. In this article, we present an electrochemical approach, which offers a new very selective methodology for obtaining alkyl polynitroaromatic compounds. Different strategies based on the use of tetralkylborate anion as nucleophiles are used so as to increase efficiency and to reduce the drawbacks associated with this reaction. A wide list of dinitro- and trinitro-aromatic compounds are studied, the range of yields obtained being from fair (40%) to excellent (85%). The key to improvement in the process is the use of electrochemical techniques for the oxidation of the mixture sigma(H)-complexes/tetrabutylborate ion. The electroactive character of the nucleophile, which can be oxidized to an alkyl radical, means that the S(N)Ar of the hydrogen polar mechanism is not the only mechanism operating during the electroxidation process, since the hydrogen radical S(N)Ar mechanism is running at the same time. Electrochemical mechanistic studies allow the participation of each mechanism in the global product yield obtained to be quantified. PMID:12968884

Gallardo, Iluminada; Guirado, Gonzalo; Marquet, Jordi

2003-09-19

124

Electrochemical Oxidation of Synthetic Dyes in Simulated Wastewaters  

NASA Astrophysics Data System (ADS)

An electrochemical oxidation method for the degradation of synthetic reactive azodyes found in textile wastewaters is discussed. Four commercial synthetic dyes (black, blue, red and yellow) commonly used in dying operations were studied in single, binary and ternary mixtures. Low (100 mg/L) and high (500, 1,000 and 2,000 mg/L) initial dye concentrations were studied. The effect of various sodium chloride concentrations (as supporting electrolyte) on the effectiveness of electrochemical oxidation was examined. The effect of current intensity (1.5, 2.5 and 3.0 A) and pH (vales 3, 5, 7 and 10) was studied as well. The kinetics of the electrochemical oxidation for each dye were studied and compared. The conditions for effective dye degradation even from 2,000 mg/L initial concentration were established. The method was proved very effective even with binary and ternary mixtures of basic synthetic dyes. The Chemical Oxygen Demand (COD) and the Total Organic Carbon (TOC) were reduced by 60% and 25% respectively, meaning that the treated solutions were friendlier to the environment.

Gallios, G.; Violintzis, X.; Voinovskii, I.; Voulgaropoulos, A.

125

Amperometric detection of cholesterol using an indirect electrochemical oxidation method.  

PubMed

The indirect electrochemical oxidation method using bromine species in an organic media for measuring cholesterol was developed. The electrochemical behaviors of cholesterol were examined by cyclic voltammetry in a potential range of -0.5 to 2.0V (vs. Ag/AgCl/saturated KCl). The polarization curve of the steady-state current in the applied potential range of 0-2.0V is reported. The obtained kinetic parameters for the catalytic oxidation of cholesterol support the assumption that positive bromine species can be generated from bromine by undergoing two consecutive electrochemical oxidation steps. The positive bromine acts both as electron mediators and as electrocatalysts. Amperometric detection with an anodic current was investigated, and the calibration curve exhibited a linear relationship between the steady-state current and the concentration of cholesterol in the range of 30-200 ?M, from which the sensitivity was calculated to be about 0.2 ?A/cm2/?M. Moreover, the amperometric current followed Michaelis-Menten's enzymatic model for cholesterol concentrations in the range of 30 ?M to 5mM, which can be applied for cholesterol rapid detection in processed foods. PMID:21964246

Chiang, Wei-Hung; Chen, Po-Yen; Nien, Po-Chin; Ho, Kuo-Chuan

2011-09-21

126

Advanced materials for solid oxide fuel cells  

SciTech Connect

The purpose of this research is to improve the properties of the current state-of-the-art materials used for solid oxide fuel cells (SOFCs). The objectives are to: (1) develop materials based on modifications of the state-of-the-art materials; (2) minimize or eliminate stability problems in the cathode, anode, and interconnect; (3) Electrochemically evaluate (in reproducible and controlled laboratory tests) the current state-of-the-art air electrode materials and cathode/electrolyte interfacial properties; (4) Develop accelerated electrochemical test methods to evaluate the performance of SOFCs under controlled and reproducible conditions; and (5) Develop and test materials for use in low-temperature SOFCs.

Armstrong, T.; Stevenson, J.

1995-12-31

127

Sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells  

DOEpatents

An electrochemical apparatus is made containing an exterior electrode bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

Isenberg, Arnold O. (Pittsburgh, PA)

1987-01-01

128

Numerical simulation for electrochemical cultivation of iron oxidizing bacteria.  

PubMed

A numerical simulation model was constructed for electrochemical cultivation of iron oxidizing bacterium, Thiobacillus ferrooxidans, based on Monod's dual limitation equation. In this model, two limiting factors were examined, low supply of Fe(II) ion and dissolved oxygen, from empirical viewpoints. The simulation model was constructed taking into consideration the energy balance based on the amount of the electronic flow from the electrode to bacteria via an iron ion, and then to oxygen. The model consisted of a logarithmic bacterial growth phase during the first three days, followed by a plateau and growth limitation thereafter. The predicted results were in agreement with the actual growth under electrochemical cultivation. It was predicted the growth limiting factor would be changed from insufficient supply of Fe(II) ions to that of oxygen by decreasing the value of oxygen transfer constant K, which correlated with the aeration rate. The optimum aeration rate was determined for the ideal electrochemical cultivation. The algorithm described here can be used in any electrochemical cultivation by modifying the parameters for each system. PMID:11857276

Matsumoto, Norio; Yoshinaga, Hisao; Ohmura, Naoya; Ando, Akikazu; Saiki, Hiroshi

2002-04-01

129

Zinc oxide\\/redox mediator composite films-based sensor for electrochemical detection of important biomolecules  

Microsoft Academic Search

Electrochemical oxidation of serotonin (SN) onto zinc oxide (ZnO)-coated glassy carbon electrode (GCE) results in the generation of redox mediators (RMs) that are strongly adsorbed on electrode surface. The electrochemical properties of zinc oxide-electrogenerated redox mediator (ZnO\\/RM) (inorganic\\/organic) hybrid film-coated electrode has been studied using cyclic voltammetry (CV). The scanning electron microscope (SEM), atomic force microscope (AFM), and electrochemical techniques

Chun-Fang Tang; S. Ashok Kumar; Shen-Ming Chen

2008-01-01

130

The electrochemical deoxidation of metal oxides by calcium using a solid oxide membrane  

NASA Astrophysics Data System (ADS)

The reduction of a metal oxide by calcium in a CaCl2 melt produces metal and calcium oxide (CaO) dissolved in the molten chloride. To minimize waste salts, the reacted salts have to be regenerated. This can be done either by converting CaO to CaCl2 by chlorination with Cl2 and adding calcium metal or by electrochemical deoxidation of CaO. In the first method, the addition of calcium metal increases the amount of reacted salts, and consequently the waste salts, while in the second method the quantity of reacted salts remains constant. The electrochemical deoxidation of CaO occurs in one step and the produced oxygen is evacuated. This article describes a study of the electrochemical deoxidation of CaO using a solid oxide membrane.

Martin, A.; Lambertin, D.; Poignet, J.-C.; Allibert, M.; Bourges, G.; Pescayre, L.; Fouletier, J.

2003-10-01

131

Electrochemical sensing and biosensing platform based on chemically reduced graphene oxide.  

PubMed

In this paper, the characterization and application of a chemically reduced graphene oxide modified glassy carbon (CR-GO/GC) electrode, a novel electrode system, for the preparation of electrochemical sensing and biosensing platform are proposed. Different kinds of important inorganic and organic electroactive compounds (i.e., probe molecule (potassium ferricyanide), free bases of DNA (guanine (G), adenine (A), thymine (T), and cytosine (C)), oxidase/dehydrogenase-related molecules (hydrogen peroxide (H2O2)/beta-nicotinamide adenine dinucleotide (NADH)), neurotransmitters (dopamine (DA)), and other biological molecules (ascorbic acid (AA), uric acid (UA), and acetaminophen (APAP)) were employed to study their electrochemical responses at the CR-GO/GC electrode, which shows more favorable electron transfer kinetics than graphite modified glassy carbon (graphite/GC) and glassy carbon (GC) electrodes. The greatly enhanced electrochemical reactivity of the four free bases of DNA at the CR-GO/GC electrode compared with that at graphite/GC and GC electrodes makes the CR-GO/GC electrode a better choice for the electrochemical biosensing of four DNA bases in both the single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) at physiological pH without a prehydrolysis step. This allows us to detect a single-nucleotide polymorphism (SNP) site for short oligomers with a particular sequence at the CR-GO/GC electrode without any hybridization or labeling processes in this work, suggesting the potential applications of CR-GO in the label-free electrochemical detection of DNA hybridization or DNA damage for further research. Based on the greatly enhanced electrochemical reactivity of H2O2 and NADH at the CR-GO/GC electrode, CR-GO/GC electrode-based bioelectrodes (in connection with glucose oxidase (GOD) and alcohol dehydrogenase (ADH)) show a better analytical performance for the detection of glucose and ethanol compared with graphite/GC- or GC-based bioelectrodes. By comparing the electrochemical performance of CR-GO with that of the conventional graphite and GC, we reveal that CR-GO with the nature of a single sheet showing favorable electrochemical activity should be a kind of more robust and advanced carbon electrode material which may hold great promise for electrochemical sensors and biosensors design. PMID:19522529

Zhou, Ming; Zhai, Yueming; Dong, Shaojun

2009-07-15

132

Current status of environmental, health, and safety issues of electrochemical capacitors for advanced vehicle applications  

Microsoft Academic Search

Electrochemical capacitors are a candidate for traction power assists in hybrid electric vehicles (HEVs). Other advanced automotive applications, while not the primary focus of current development efforts, are also possible. These include load leveling high-energy batteries, power conditioning electronics, electrically hated catalysts, electric power steering, and engine starter power. Higher power and longer cycle life are expected for electrochemical capacitors

L. J. Vimmerstedt; C. J. Hammel

1997-01-01

133

Current status of environmental, health, and safety issues of electrochemical capacitors for advanced vehicle applications  

SciTech Connect

Electrochemical capacitors are a candidate for traction power assists in hybrid electric vehicles (HEVs). Other advanced automotive applications, while not the primary focus of current development efforts, are also possible. These include load leveling high-energy batteries, power conditioning electronics, electrically hated catalysts, electric power steering, and engine starter power. Higher power and longer cycle life are expected for electrochemical capacitors than for batteries. Evaluation of environmental, health, and safety (EH and S) issues of electrochemical capacitors is an essential part of the development and commercialization of electrochemical capacitors for advanced vehicles. This report provides an initial EH and S assessment. This report presents electrochemical capacitor electrochemistry, materials selection, intrinsic material hazards, mitigation of those hazards, environmental requirements, pollution control options, and shipping requirements. Most of the information available for this assessment pertains to commercial devices intended for application outside the advanced vehicle market and to experiment or prototype devices. Electrochemical capacitors for power assists in HEVs are not produced commercially now. Therefore, materials for advanced vehicle electrochemical capacitors may change, and so would the corresponding EH and S issues. Although changes are possible, this report describes issues for likely electrochemical capacitor designs.

Vimmerstedt, L.J.; Hammel, C.J.

1997-04-01

134

Oxidation of enrofloxacin with conductive-diamond electrochemical oxidation, ozonation and Fenton oxidation: a comparison.  

PubMed

The treatment of enrofloxacin synthetic wastewaters using conductive-diamond electrochemical oxidation (CDEO), ozonation and Fenton oxidation has been studied. Results show that the three technologies can reduce the organic content of enrofloxacin synthetic wastewaters but with different performances. CDEO was the most efficient technology in terms of mineralization but not on COD removal, which was more efficiently achieved by ozonation. This indicates that ozonation is efficient in the breakage of the complex molecules but not on the removal of final carboxylic acids. The high initial efficiency in terms of oxidant-use obtained by Fenton oxidation evidences that it is very efficient in the removal of the enrofloxacin, although it rapidly leads to the formation of refractory compounds to the treatment. This indicates the significance of other oxidation mechanisms (e.g. coagulation) that enhance the results obtained by the expected hydroxyl-mediated oxidation. Ammonium ions were the primary product species in CDEO and nitrate ions in ozonation, whereas Fenton effluents contained similar amounts of both nitrogen ionic species. PMID:19282017

Guinea, Elena; Brillas, Enric; Centellas, Francesc; Cañizares, Pablo; Rodrigo, Manuel A; Sáez, Cristina

2009-02-27

135

Electrochemical oxidation by square-wave potential pulses in the imitation of oxidative drug metabolism.  

PubMed

Electrochemistry combined with mass spectrometry (EC-MS) is an emerging analytical technique in the imitation of oxidative drug metabolism at the early stages of new drug development. Here, we present the benefits of electrochemical oxidation by square-wave potential pulses for the oxidation of lidocaine, a test drug compound, on a platinum electrode. Lidocaine was oxidized at constant potential and by square-wave potential pulses with different cycle times, and the reaction products were analyzed by liquid chromatography-mass spectrometry [LC-MS(/MS)]. Application of constant potentials of up to +5.0 V resulted in relatively low yields of N-dealkylation and 4-hydroxylation products, while oxidation by square-wave potential pulses generated up to 50 times more of the 4-hydroxylation product at cycle times between 0.2 and 12 s (estimated yield of 10%). The highest yield of the N-dealkylation product was obtained at cycle times shorter than 0.2 s. Tuning of the cycle time is thus an important parameter to modulate the selectivity of electrochemical oxidation reactions. The N-oxidation product was only obtained by electrochemical oxidation under air atmosphere due to reaction with electrogenerated hydrogen peroxide. Square-wave potential pulses may also be applicable to modulate the selectivity of electrochemical reactions with other drug compounds in order to generate oxidation products with greater selectivity and higher yield based on the optimization of cycle times and potentials. This considerably widens the scope of direct electrochemistry-based oxidation reactions for the imitation of in vivo oxidative drug metabolism. PMID:21644593

Nouri-Nigjeh, Eslam; Permentier, Hjalmar P; Bischoff, Rainer; Bruins, Andries P

2011-06-27

136

Electrochemical behavior of cobalt oxide coatings on cold-rolled steel in alkaline sodium sulfate  

Microsoft Academic Search

The electrochemical behavior of a coating of cobalt oxide on cold-rolled steel in alkaline sodium sulfate was studied using the electrochemical techniques of open-circuit potential measurements and electrochemical impedance spectroscopy. The coating was prepared at different annealing temperatures ranging from 350 to 750 °C and characterized by SEM, EDX and XRD. Below 550 °C the composition of the coating was

G. C. Silva; C. S. Fugivara; G. Tremiliosi Filho; P. T. A. Sumodjo; A. V. Benedetti

2002-01-01

137

Composite electrodes for advanced electrochemical applications. Quarterly report for the period July 1 - September 30, 1999.  

National Technical Information Service (NTIS)

The electrochemical industry is one of the most highly energy-intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a l...

C. Kovach

1999-01-01

138

Fabrication of solid oxide fuel cell by electrochemical vapor deposition  

DOEpatents

In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (/approximately/1100/degree/ /minus/ 1300/degree/C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20--50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

Riley, B.; Szreders, B.E.

1988-04-26

139

Fabrication of solid oxide fuel cell by electrochemical vapor deposition  

DOEpatents

In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approximately 1100.degree.-1300.degree. C.) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20-50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

Brian, Riley (Willimantic, CT); Szreders, Bernard E. (Oakdale, CT)

1989-01-01

140

Effect of base pairing on the electrochemical oxidation of guanine.  

PubMed

The effect of base pairing by cytosine on the electrochemical oxidation of guanine is examined by means of cyclic voltammetry on carefully purified reactants in a solvent, CHCl(3), which strongly favors the formation of an H-bonded pair. The thermodynamics and kinetics of the oxidation reaction are not strongly influenced by the formation of the pair. They are actually similar to those of the reaction in which 2,6-lutidine, an encumbered base that cannot form a pair with guanine, replaces cytosine. The reaction does not entail a concerted proton-electron mechanism, as attested by the absence of H/D isotope effect. It rather involves the rate-determining formation of the cation radical, followed by its deprotonation and dimerization of the resulting neutral radical in competition with its further oxidation. PMID:20597511

Costentin, Cyrille; Hajj, Viviane; Robert, Marc; Savéant, Jean-Michel; Tard, Cédric

2010-07-28

141

Stacked graphene nanofibers for electrochemical oxidation of DNA bases.  

PubMed

In this article, we show that stacked graphene nanofibers (SGNFs) demonstrate superior electrochemical performance for oxidation of DNA bases over carbon nanotubes (CNTs). This is due to an exceptionally high number of accessible graphene sheet edges on the surface of the nanofibers when compared to carbon nanotubes, as shown by transmission electron microscopy and Raman spectroscopy. The oxidation signals of adenine, guanine, cytosine, and thymine exhibit two to four times higher currents than on CNT-based electrodes. SGNFs also exhibit higher sensitivity than do edge-plane pyrolytic graphite, glassy carbon, or graphite microparticle-based electrodes. We also demonstrate that influenza A(H1N1)-related strands can be sensitively oxidized on SGNF-based electrodes, which could therefore be applied to label-free DNA analysis. PMID:20532301

Ambrosi, Adriano; Pumera, Martin

2010-06-07

142

The electrochemical oxidation of organic selenides and selenoxides  

SciTech Connect

The electrochemical oxidation of alkyl and aryl selenides was investigated in acetonitrile. The oxidation of diphenyl selenide and di(4-methylphenyl) selenide led primarily to the formation of their respective selenoxides, which were identified by exhaustive coulometric oxidation and {sup 1}H and {sup 13}C analysis of the products. The selenoxide itself was not observed in the cyclic voltammetry of the selenide for two reasons: first, the protonation of the selenoxide by the acid formed from the reaction of water with the cation radical and second, the formation of a selenoxide hydrate. The formation of the hydrate with diphenyl selenoxide was verified by isolation of the dimethoxy derivative. In addition to the selenoxide, selenonium compounds, formed by the coupling of the oxidized material, were also observed. The alkyl selenides were generally oxidized at a lower potential than the aryl selenides. This trend is different from the sulfur analogues, where the aryl sulfides are easier to oxidize than their alkyl counterparts. As a result, the difference in their redox potentials is relatively small. These differences may occur because the oxidation of aryl sulfides is more likely to take place on the aromatic ring, which leads to a greater yield of the coupled products (about 100%) when compared to the selenide analogue.

Ryan, M.D.; Yau, J.; Hack, M. [Marquette Univ., Milwaukee, WI (United States). Dept. of Chemistry

1997-06-01

143

Hydrothermally enhanced electrochemical oxidation of high concentration refractory perfluorooctanoic acid.  

PubMed

A green hydrothermally enhanced electrochemical oxidation (HTEO) technique is developed to treat the high concentration refractory perfluorooctanoic acid (PFOA) wastewater on boron-doped diamond (BDD) film electrode. Results show that HTEO can demonstrate higher degradation efficiency for PFOA than the normal electrochemical oxidation (EO) process, with the removal of PFOA, total organic carbon (TOC), and organic fluorine in the HTEO process increasing by 1.1, 1.8, and 2.1 times, respectively. The kinetics study indicates that the degradation of PFOA follows a first-order reaction in the HTEO process with the apparent reaction rate constant 3.1 times higher than that in the EO process. The higher degradation efficiency of PFOA is due to the hydrothermal enhancement in electrochemical properties of the electrode and solution. Compared with EO, during the HTEO process, the conductivity and ionic migration rate of the solution is improved by 540% and 60%, respectively. In addition, the Tafel slope is increased to 343 from 279 mV dec(-1), indicating an inhibition effect of oxygen evolution reaction and a more effective oxidation of PFOA. In particular, the hydrothermal condition promotes a high formation rate of hydroxyl radical with the concentration almost 2 times of that in EO, which is considered the inner factor leading to the higher degradation efficiency. The density functional theory simulations demonstrate that the nonterminal C-C bonds in the main carbon chain can be easily destructed in the hydrothermal condition, as confirmed by the experimental detection of intermediates of C(5)F(11)COOH, C(4)F(9)COOH, C(3)F(7)COOH, C(2)F(5)COOH, CF(3)COOH, and some dicarboxylic acids. As a result, a reaction pathway is tentatively proposed. PMID:22013988

Xiao, Hanshuang; Lv, Baoying; Zhao, Guohua; Wang, Yujing; Li, Mingfang; Li, Dongming

2011-11-04

144

Electrochemical detection of nitric oxide using polymer modified electrodes.  

PubMed

Electrochemical sensors based on chemical surface modification are very attractive because they combine high sensitivity of amperometry with new dimensions of selectivity and stability provided by the surface modifier. This review shows a few strategies employed to facilitate the detection, determination and monitoring of nitric oxide using polymer modified electrodes. Conducting and nonconducting polymer films and composite films are considered. The most significant achievements reached in this field, during the last decade, are critically reviewed. The collected data are also presented in three tables. PMID:18969158

Ciszewski, Aleksander; Milczarek, Grzegorz

2003-09-30

145

Electrochemical oxidation of reverse osmosis concentrate on mixed metal oxide (MMO) titanium coated electrodes  

Microsoft Academic Search

Reverse osmosis (RO) membranes have been successfully applied around the world for wastewater reuse applications. However, RO is a physical separation process, and besides the clean water stream (permeate) a reverse osmosis concentrate (ROC) is produced, usually representing 15–25% of the feed water flow and containing the organic and inorganic contaminants at higher concentrations. In this study, electrochemical oxidation was

Arseto Y. Bagastyo; Jelena Radjenovic; Yang Mu; René A. Rozendal; Damien J. Batstone; Korneel Rabaey

2011-01-01

146

Self-organized high-aspect-ratio nanoporous zirconium oxides prepared by electrochemical anodization  

Microsoft Academic Search

The preparation of self-organized high-aspect-ratio nanoporous zirconium oxides by the Electrochemical anodization was analyzed. The self-organized pore formation on Ti under optimized electrochemical conditions was achieved to grow Ti nanotubes with aspect ratio of more than 20. The electrochemical fabrication of highly ordered porous zirconium oxide layers of nanotubular shape with high aspect ratio was also reported. Result shows that

Hiroaki Tsuchiya; Irina Sieber; Patrik Schmuki

2005-01-01

147

Mediated Electrochemical Oxidation (MEO) based technology. Final report  

SciTech Connect

The goal of this CRADA was the continued research and development by LLNL, and the commercialization by EOSystems, Inc., of the waste treatment technology known as Mediated Electrochemical Oxidation. MEO is a non-thermal electrochemical technology developed in part at LLNL for the destruction of organic waste streams; this technology has wide applications in the government, manufacturing, biomedical and industrial sectors. The system uses an electrochemical cell to generate highly oxidizing {open_quote}mediators{close_quote} in an acidic aqueous solution, which subsequently react with organic waste and convert it to carbon dioxide and water. The broad research responsibilities of LLNL in this CRADA were the investigation of numerous cell electrode materials and materials of construction, the evaluation of the process chemistry, and the testing of a flow visualization cell and a functional prototype. Major deliverables included: a determination of suitable electrode materials, an investigation of the destruction efficiency for numerous organic substrates, the construction and testing of a flow visualization cell, and the testing of a functional prototype commercial cell. The responsibilities of EOSystems included the definition of the market and potential customers, the design and engineering of the flow visualization and prototype cells, and the commercialization of the MEO units. Deliverables included the selection of the process and ancillary systems, the design of a flow visualization cell, and the design and construction of a prototype cell. In general, most of the deliverables were met by both partners, although unexpected technical difficulties delayed some of the delivery dates and forced the adoption of a modified statement of work. However, the primary, original project goals were completed on-time and on-budget.

NONE

1996-07-18

148

Oxidation of organics in water in microfluidic electrochemical reactors: Theoretical model and experiments  

Microsoft Academic Search

The electrochemical oxidation of organics in water performed in micro reactors on boron doped diamond (BDD) anode was investigated both theoretically and experimentally in order to find the influence of various operative parameters on the conversion and the current efficiency CE of the process. The electrochemical oxidation of formic acid (FA) was selected as a model case. High conversions for

Onofrio Scialdone; Chiara Guarisco; Alessandro Galia

149

Atmospheric and electrochemical oxidation of the surface of chalcopyrite (CuFeS 2)  

Microsoft Academic Search

Atmospheric and electrochemical oxidation of the surface of chalcopyrite has been investigated using electrochemical techniques with subsequent surface analysis by X-ray photoelectron spectroscopy (XPS) and aqueous phase analysis by inductively coupled plasma-atomic emission spectrometry (ICPAES). The extent of atmospheric oxidation of chalcopyrite was assessed qualitatively by measuring the increase in the open circuit potential; quantitative estimation was made either by

Q. Yin; G. H. Kelsall; D. J. Vaughan; K. E. R. England

1995-01-01

150

Transformable Oxidation of Tantalum in Electrochemical Mechanical Polishing (ECMP)  

NASA Astrophysics Data System (ADS)

A new methodology has been developed to investigate the oxidation state and processing of tantalum (Ta) during an electrochemical mechanical polishing (ECMP) process. Polishing experiments under different mechanical forces were conducted at constant potential. Faraday's law was used to calculate the material removal rate (MRR), which was compared with measurements using an atomic force microscope (AFM). It was found that there were multiple valences of Ta and unknown types of its oxides formed during ECMP. The Preston equation was tailored to the current polishing conditions, showing that the MRR was a linear function of a mechanical force. It was found that, during ECMP, metastable oxides of Ta were formed. With higher mechanical force, more Ta suboxides were formed, while with lower mechanical force, more Ta pentoxide appeared. Such a mechano-oxidation process, from suboxides to the pentoxide, was illustrated using a physical model where the transition from suboxides to the pentoxide dominated. The present research demonstrates an effective ex situ method to study the in situ oxidation process of Ta. The present approach can be applied to other materials as well, and used to help researchers to understand and optimize the ECMP process.

Gao, F.; Liang, H.

2011-02-01

151

Electrochemical insertion of magnesium in open-ended vanadium oxide nanotubes  

Microsoft Academic Search

Vanadium oxide nanotubes were obtained as the main product in a sol–gel reaction followed by hydrothermal treatment from V2O5 precursors and octadecylamine. The tubes consist of concentric shells of highly crystalline vanadium oxide separated by alternation organic amine layers. The vanadium oxide nanotubes are redox-active and can electrochemically insert magnesium reversibly. The electrochemical insertion magnesium properties of vanadium oxide nanotubes

Lifang Jiao; Huatang Yuan; Yuchang Si; Yijing Wang; Jiansheng Cao; Xiuling Gao; Ming Zhao; Xingdi Zhou; Yongmei Wang

2006-01-01

152

Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode.  

PubMed

Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12h, the COD was decreased from 532 to 99 mg L(-1) (<100 mg L(-1), the National Discharge Standard of China). More importantly, the destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters. PMID:21377794

Zhu, Xiuping; Ni, Jinren; Wei, Junjun; Xing, Xuan; Li, Hongna

2011-03-05

153

Cyclic voltammetric deposition of hydrous ruthenium oxide for electrochemical capacitors: effects of codepositing iridium oxide  

Microsoft Academic Search

The electrochemical and textural characteristics of various hydrous ruthenium–iridium oxides (denoted as (Ru+Ir)Ox·nH2O) grown by cyclic voltammetry (CV) were systematically studied for the application of electrochemical (EC) capacitors. The faradaic pseudocapacitance of (Ru+Ir)Ox·nH2O reached the maximum when the depositing solution contained 5 mM RuCl3·xH2O and 1 mM IrCl3·xH2O. The linear dependence of Ccp on Cq* measured respectively by chronopotentiometry (CP)

Chi-Chang Hu; Kwang-Huei Chang

2000-01-01

154

DEVELOPMENT OF ELECTROCHEMICAL REDUCTION TECHNOLOGY FOR SPENT OXIDE FUELS  

Microsoft Academic Search

The Advanced Spent Fuel Conditioning Process (ACP) has been under development at Korea Atomic Energy Research Institute (KAERI) since 1997. The concept is to convert spent oxide fuel into metallic form and to remove high heat-load fission products such as Cs and Sr from the spent fuel. The heat power, volume, and radioactivity of spent fuel can decrease by a

Jin-Mok Hur; Chung-Seok Seo; Ik-Soo Kim; Sun-Seok Hong; Dae-Seung Kang; Seong-Won Park

2003-01-01

155

Effect of the current intensity in the electrochemical oxidation of aqueous phenol wastes at an activated carbon and steel anode  

Microsoft Academic Search

The effect of the current intensity in the electrochemical oxidation of aqueous phenol wastes at an activated carbon and steel anode was investigated. Results confirm that three reaction pathways were involved in the electrochemical process: direct degradation or electrochemical cold combustion, chemical oxidation, and polymerization. The chemical oxidation pathway was the most important for the range of current intensities studied.

P. Canizares; J. A. Dominguez; M. A. Rodrigo; J. Villasenor; J. Rodriguez

1999-01-01

156

Electrochemical oxidation of carbon fibers: Properties, surface chemistry and morphology  

NASA Astrophysics Data System (ADS)

A series of PAN-based T300 carbon fibers was continuously, electrochemically oxidized in aqueous and organic media. A 30% fiber weight loss was obtained at an extent of oxidation of 10,600 C/g. Acidic functional groups were produced on fiber surfaces in amounts from 0 to 2640 mumol/g as the extent of oxidation increased from 0 to 10600 C/g. These surface functions were further reacted with diethylenetriamine to introduce amine functions onto fibers. The oxidation extended far deeper than the XPS detection limit (<100 A). N 2 BET at 77K gave very low fiber specific surface area in contrast to CO2 DR measurements at 273 K which confirmed large increases in surface area with oxidation. No heavy damage or macro-/mesopores were found in scanning electron micrographs. An ultramicropore structure was characterized by the CO2 DR method combined with nonlocal density functional theory. The average pore diameter was about 1.2 nm with a dominant pore diameter of 0.4 nm. CCl4, methylene blue, I2, AgNO3, and Ni(NO3)2 adsorption studies were performed. A pH-dependent swelling model was discussed. In basic media, a solvation/swelling process allows small molecules to penetrate the microporous channels and react with fiber functional groups. A remote site silver reduction/adsorption model was confirmed based upon high AgNO3 adsorption and qualitative experiments. Single filament breaking and fragmentation tests and fiber/epoxy composite mechanical tests were conducted. Fiber/epoxy matrix adhesion was improved by oxidation although the fiber tensile strength decreased. Post-heat treatment causes further weight loss and the loss of oxygen-containing surface functional groups.

Jiang, Wenbo

1999-10-01

157

Electrochemical oxidation and reuse of tannery saline wastewater.  

PubMed

In this present work, electrochemical treatment of saline wastewater with organic (protein) load was studied. The influence of the critical parameters of electro-oxidation such as pH, period, salt concentration and current density on the reduction of organic load was studied using graphite electrodes. It was found that current density of 0.024 A/cm(2) for a period of 2 h at pH 9.0 rendered best results in terms of reduction in COD and TKN. The energy requirement for the reduction of 1 kg of TKN and 1 kg of COD are 22.45 kWh and 0.80 kWh respectively at pH 9 and 0.024 A/cm(2). Reuse experiments were conducted at commercial scale. One of the saline waste streams in leather manufacturing process, pickling was treated and reused continuously thrice. The characteristics of the waste stream and the quality of the leathers indicate that the reuse of saline streams with intermittent electrochemical treatment is feasible. PMID:20435417

Sundarapandiyan, S; Chandrasekar, R; Ramanaiah, B; Krishnan, S; Saravanan, P

2010-04-13

158

Electrochemical oxidation in solid oxide fuel cells -- Where does it occur and how?  

NASA Astrophysics Data System (ADS)

Electrochemical processes in solid-oxide fuel cells (SOFCs) are thought to occur at a ``triple phase boundary'' (TPB) -- that junction between a conducting anode, a solid oxide electrolyte and the gas phase fuel mixture. A quantitative, physical description of this boundary, however, remains elusive given difficulties associated with probing molecular species present in SOFCs under realistic operating conditions of high temperatures and reducing atmospheres. Recently, we have constructed an SOFC that has optical access to the anode assembly allowing us to probe with Raman spectroscopy the chemical intermediates present on anode and electrolyte surfaces as carbon containing fuels are electrochemically oxidized. Results show that chemistry occurs on both the anode and electrolyte surfaces as well as in the vicinity of the purported TPB. The reduced electrolyte surface is both catalytically active and, over micron distances, electrically conductive. The Ni anode shows strong evidence of adsorbed carboxylate intermediates. This talk will address mechanisms of electrochemical oxidation in SOFCs using direct and indirect experimental probes as well as the consequence of our findings for models of a well defined triple phase boundary.

Walker, Robert; Pomfret, Michael

2006-03-01

159

Advanced oxidation processes for the treatment of olive-oil mills wastewater.  

PubMed

In this work, the treatment of an actual industrial waste with three advanced oxidation processes (AOP) has been studied: conductive-diamond electrooxidation (CDEO), ozonation and Fenton oxidation. The wastewater comes from olive-oil mills (OMW) and contains a COD of nearly 3000 mg dm(-3). CDEO allowed achieving the complete mineralization of the waste with high current efficiencies. Likewise, both ozonation and Fenton oxidation were able to treat the wastes, but they obtained very different results in terms of efficiency and mineralization. The accumulation of oxidation-refractory compounds as final products excludes the use of ozonation and Fenton oxidation as a sole treatment technology. This confirms that besides the hydroxyl-radical mediated oxidation, CDEO combines other important oxidation processes such as the direct electro-oxidation on the diamond surface and the oxidation mediated by other electrochemically formed compounds generated on this electrode. PMID:17208280

Cañizares, P; Lobato, J; Paz, R; Rodrigo, M A; Sáez, C

2007-01-08

160

ELECTROCHEMICAL REDUCTION OF URANIUM OXIDES IN Li2O-LiCl MOLTEN-SALT  

Microsoft Academic Search

A concept of electrochemical reduction of spent oxide fuel in Li2O-LiCl molten-salt was proposed and several cold tests using fresh uranium oxides have been carried out at KAERI. In this new electrochemical reduction process, electrolysis of Li2O and reduction of uranium oxide are taking place simultaneously at the cathode part of electrolysis cell. Li produced via Li2O electrolysis reacts with

Jin-Mok Hur; Chung-Seok Seo; Sun-Seok Hong; Dae-Seung Kang; Seong-Won Park

161

Oxidation of alloys for advanced steam turbines  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections.

Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Ziomek-Moroz, M.; Alman, David E.

2005-01-01

162

Metal oxide nanoparticles for advanced energy applications  

Microsoft Academic Search

Hot-wire chemical vapor deposition (HWCVD) has been employed as an economically scalable method for the deposition of crystalline molybdenum oxide nanoparticles at high density. Under optimal synthesis conditions, only crystalline nanostructures with a smallest dimension of ~3–50 nm are observed with extensive transmission electron microscopy analyses. The incorporation of crystalline molybdenum oxide nanoparticles into battery electrodes has led to profound advancements

Se-Hee Lee; Rohit. Deshpande; Daniel Benhammou; Phil A. Parilla; A. Harv Mahan; Anne C. Dillon

2009-01-01

163

Microwave-electrochemical formation of colloidal zinc oxide at fluorine doped tin oxide electrodes  

Microsoft Academic Search

Colloidal ZnO is obtained during microwave-enhanced electrochemical deposition experiments from an aqueous solution containing 0 1 M Zn(NO(3))(2) and 0 02 M H(2)O(2) via repetitive negative going potential cycles from 03 to 0 8 V vs SCE The effects of temperature and temperature gradients on ZnO electro formation at fluorine doped tin oxide (FTO) electrodes are investigated with both a

Liza Rassaei; Robben Jaber; Stephen E. Flower; Karen J. Edler; Richard G. Compton; Tony D. James; Frank Marken

2010-01-01

164

Lithium assisted electrochemical reduction of uranium oxide in room temperature ionic liquid  

Microsoft Academic Search

Lithium assisted electrochemical reduction of U3O8 in the room temperature ionic liquid (RTIL), N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2), was studied to explore the feasibility of using RTILs for direct electrochemical reduction of uranium oxide at near ambient\\u000a temperature. The electrochemical behavior of Li+ in MPPiNTf2 at stainless steel electrode was investigated by cyclic voltammetry and chronoamperometry. The cyclic voltammogram of LiNTf2 in

Biju Joseph; K. A. Venkatesan; K. Nagarajan; T. G. Srinivasan; P. R. Vasudeva Rao

2011-01-01

165

Electrochemical oxidation by square-wave potential pulses in the imitation of phenacetin to acetaminophen biotransformation.  

PubMed

Electrochemistry in combination with mass spectrometry is emerging as a versatile analytical technique in the imitation of oxidative drug metabolism during the early stages of drug discovery and development. Here, we present electrochemical O-dealkylation of phenacetin to acetaminophen by square-wave potential pulses consisting of consecutive sub-second oxidation and reduction steps. This O-dealkylation could not be achieved by oxidation at constant potential or longer potential pulses because of the fast hydrolysis of the reactive intermediates. Electrochemical conversion by square-wave potential pulses can thus widen the scope of electrochemical synthesis of metabolites and imitation of in vivo drug metabolism. PMID:21984979

Nouri-Nigjeh, Eslam; Bischoff, Rainer; Bruins, Andries P; Permentier, Hjalmar P

2011-10-07

166

Electrochemical hydrogen property improved in nano-structured perovskite oxide LaFeO3 for Ni/MH battery  

NASA Astrophysics Data System (ADS)

Perovskite oxide LaFeO3, as a novel candidate for the electrode of Ni/MH battery, holds high specific capacity and good cyclical durability at elevated temperatures. However, the poor electrochemical kinetics is a bottleneck for the application of this type of material. By use of nano-structured materials, there are greatly enhanced values of exchange current density I0 and hydrogen diffusion coefficient D, which resulted in an improvement of electrochemical kinetics, a much higher specific capacity and excellent stability during cycling for nano-structured LaFeO3. In theory, there is a significant possibility of further advancing the hydrogen reaction kinetics of perovskite type oxides for Ni/MH battery.

Wang, Qiang; Deng, Gang; Chen, Zhiqian; Chen, Yungui; Cheng, Nanpu

2013-02-01

167

Treatment and toxicity evaluation of methylene blue using electrochemical oxidation, fly ash adsorption and combined electrochemical oxidation-fly ash adsorption.  

PubMed

Treatment of a basic dye, methylene blue, by electrochemical oxidation, fly ash adsorption, and combined electrochemical oxidation-fly ash adsorption was compared. Methylene blue at 100 mgL(-1) was used in this study. The toxicity was also monitored by the Vibrio fischeri light inhibition test. When electrochemical oxidation was used, 99% color and 84% COD were removed from the methylene blue solution in 20 min at a current density of 428 Am(-2), NaCl of 1000 mgL(-1), and pH(0) of 7. However, the decolorized solution showed high toxicity (100% light inhibition). For fly ash adsorption, a high dose of fly ash (>20,000 mgL(-1)) was needed to remove methylene blue, and the Freundlich isotherm described the adsorption behavior well. In the combined electrochemical oxidation-fly ash adsorption treatment, the addition of 4000 mgL(-1) fly ash effectively reduced intermediate toxicity and decreased the COD of the electrochemical oxidation-treated methylene blue solution. The results indicated that the combined process effectively removed color, COD, and intermediate toxicity of the methylene blue solution. PMID:20399000

Wang, Kai-sung; Wei, Ming-Chi; Peng, Tzu-Huan; Li, Heng-Ching; Chao, Shu-Ju; Hsu, Tzu-Fang; Lee, Hong-Shen; Chang, Shih-Hsien

2010-08-01

168

A reduced graphene oxide based electrochemical biosensor for tyrosine detection.  

PubMed

In this paper, a 'green' and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through ?-? interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10(-7) M to 2 × 10(-5) M with a detection limitation of 7.5 × 10(-8) M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs. PMID:22863907

Wei, Junhua; Qiu, Jingjing; Li, Li; Ren, Liqiang; Zhang, Xianwen; Chaudhuri, Jharna; Wang, Shiren

2012-08-03

169

A reduced graphene oxide based electrochemical biosensor for tyrosine detection  

NASA Astrophysics Data System (ADS)

In this paper, a ‘green’ and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through ?-? interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10-7 M to 2 × 10-5 M with a detection limitation of 7.5 × 10-8 M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.

Wei, Junhua; Qiu, Jingjing; Li, Li; Ren, Liqiang; Zhang, Xianwen; Chaudhuri, Jharna; Wang, Shiren

2012-08-01

170

Electrochemical oxidation of butein at glassy carbon electrodes.  

PubMed

The electrochemical oxidation of flavonoid butein is studied at glassy carbon electrodes in phosphate and citrate buffer solutions of different pH values, and 1M perchloric acid aqueous solutions by cyclic and square wave voltammetries. The oxidation peak corresponds to the 2e(-), 2H(+) oxidation of the 3,4-dihydroxy group in B ring of butein, given the corresponding quinone species. The overall electrode process shows a quasi-reversible behavior and an adsorption/diffusion mixed control at high butein bulk concentrations. At low butein concentrations, the electrode process shows mainly an adsorption control. Butein surface concentration values were obtained from the charge associated with the adsorbed butein oxidation peaks, which are in agreement with those values expected for the formation of a monolayer of adsorbate in the concentration range from 1 to 5?M. Square wave voltammetry was used to perform a full thermodynamic and kinetics characterization of the butein surface redox couple. Therefore, from the combination of the "quasi-reversible maximum" and the "splitting of the net square wave voltammetric peak" methods, values of (0.386±0.003) V, (0.46±0.04), and 2.7×10(2)s(-1) were calculated for the formal potential, the anodic transfer coefficient, and the formal rate constant, respectively, of the butein overall surface redox process in pH4.00 citrate buffer solutions. These results will be then used to study the interaction of butein, and other flavonoids with the deoxyribonucleic acid, in order to better understand the potential therapeutic applications of these compounds. PMID:23434740

Tesio, Alvaro Yamil; Robledo, Sebastián Noel; Fernández, Héctor; Zon, María Alicia

2013-01-23

171

HANDBOOK ON ADVANCED NONPHOTOCHEMICAL OXIDATION PROCESSES  

EPA Science Inventory

The purpose of this handbook is to summarize commercial-scale system performance and cost data for advanced nonphotochemical oxidation (ANPO) treatment of contaminated water, air, and soil. Similar information from pilot-and bench-scale evaluations of ANPO processes is also inclu...

172

HANDBOOK ON ADVANCED PHOTOCHEMICAL OXIDATION PROCESSES  

EPA Science Inventory

This handbook summarizes commercial-scale system performance and cost data for advanced photochemical oxidation (APO) treatment of contaminated water, air, and solids. Similar information from pilot- and bench-scale evaluations of APO processes is also included to supplement the...

173

Improved electrochemical biosensor response via metal oxide pre-oxidation of chemical interferents  

NASA Astrophysics Data System (ADS)

Typical biological samples are inherently complicated. They may contain a myriad of compounds that are electroactive at the same potential as that used in many electrochemical biosensors. Therefore, a biosensor design feature must be included that either eliminates or blocks the interferents from generating false positive signals. The ability to use an insoluble compound, that of MnO2, in order to oxidize interferents such as ascorbic acid, acetaminophen and uric acid, was investigated in a prototype sensor system at a bias potential of 0.6 V versus Ag/AgCl. Unlike previous work with these materials, a difference between the ability for the metal oxide to oxidize the interferents was observed. Most effective was the capability of MnO2 to oxidize uric acid. Alternatively, the MnO2 had little effect on acetaminophen. The study is both introduced and results are discussed within the context of an implantable glucose sensor.

Houseknecht, Jamie G.; Tapsak, Mark A.

2007-09-01

174

Electrochemical and Spectroscopic Studies of Some Less Stable Oxidation States of Selected Lanthanide and Actinide Elements.  

National Technical Information Service (NTIS)

Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltamm...

D. E. Hobart

1981-01-01

175

Electrochemical oxidation of a textile dye and finishing wastewater using a Pt\\/Ti electrode  

Microsoft Academic Search

Textile Dye and Finishing Wastewater (TDFW) from a reactive cellulosic azo dyeing and finishing process was treated by an electrochemical oxidation method using Ti\\/Pt as anode and Stainless Steel 304 as cathode. The strong oxidizing potential of the chemicals produced when the wastewater was passed through the electrolytic cell resulted in the oxidation of organic pollutants to carbon dioxide and

A. G. Vlyssides; C. J. Israilides

1998-01-01

176

Electrochemically Induced Oxidative Damage to Double-Stranded Calf Thymus DNA Adsorbed on Gold Electrodes  

Microsoft Academic Search

Electrochemically induced oxidative damage to DNA was studied with double-stranded calf thymus DNA immobilized directly on a gold electrode surface. Pre-polarization of the DNA-modified electrodes at +0.5 V versus Ag\\/AgCl reference electrode, in a free from DNA blank buffer solution, pH 7.4, allowed for subsequent detection of direct electrochemical oxidation of adsorbed on gold DNA, in the potential range from

E. E. Ferapontova; S. V. Shipovskov

2003-01-01

177

Direct electrochemical reduction of solid uranium oxide in molten fluoride salts  

Microsoft Academic Search

The direct electrochemical reduction of UO2 solid pellets was carried out in LiF–CaF2 (+2mass.% Li2O) at 850°C. An inert gold anode was used instead of the usual reactive sacrificial carbon anode. In this case, oxidation of oxide ions present in the melt yields O2 gas evolution on the anode. Electrochemical characterisations of UO2 pellets were performed by linear sweep voltammetry

Mathieu Gibilaro; Laurent Cassayre; Olivier Lemoine; Laurent Massot; Olivier Dugne; Rikard Malmbeck; Pierre Chamelot

2011-01-01

178

Influence of anode material on electrochemical oxidation for the treatment of tannery wastewater  

Microsoft Academic Search

The treatment of tannery wastewater by electrochemical oxidation, mediated by an electro-generated species was carried out under galvanostatic conditions in an electrochemical reactor equipped with anodes based on noble metals and metal oxides (Ti\\/Pt–Ir, Ti\\/PbO2, Ti\\/PdO–Co3O4 and Ti\\/RhOx–TiO2). The decrease in time of chemical oxygen demand, nitrogen (TKN and ammonia), Cr and sulphides was monitored. The study showed that the

Lidia Szpyrkowicz; Santosh N. Kaul; Rao N. Neti; Shanta Satyanarayan

2005-01-01

179

Facile and controllable electrochemical reduction of graphene oxide and its applications  

SciTech Connect

Graphene oxide is electrochemically reduced which is called electrochemically reduced graphene oxide (ER-G). ER-G is characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The oxygen content is significantly decreased and the sp 2 carbon is restored after electrochemical reduction. ER-G exhibits much higher electrochemical capacitance and cycling durability than carbon nanotubes (CNTs) and chemically reduced graphene; the specific capacitance measured with cyclic voltammetry (20 mV/s) is ~165 F/g, ~86 F/g, and ~100 F/g for ER-G, CNTs, and chemically reduced graphene,1 respectively. The electrochemical reduction of oxygen and hydrogen peroxide was greatly enhanced on ER-G electrodes as compared with CNTs. ER-G has shown a good potential for applications in energy storage, biosensors, and electrocatalysis.

Shao, Yuyan; Wang, Jun; Engelhard, Mark H.; Wang, Chong M.; Lin, Yuehe

2010-01-01

180

Electrochemical test methods for advanced battery and semiconductor technology  

Microsoft Academic Search

This dissertation consists of two studies. The first study was the evaluation of metallic materials for advanced lithium ion batteries and the second study was the determination of the dielectric constant k for the low-k materials. The advanced lithium ion battery is miniature for implantable medical devices and capable of being recharged from outside of the body using magnetic induction

Chao-Hung Hsu

2002-01-01

181

Advances in electrochemical detection for study of neurodegenerative disorders.  

PubMed

Several severe neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and prion-associated transmissible spongiform encephalopathies, have been linked to dysregulation of specific proteins capable of self-assembly into deleterious fibrillar aggregates termed amyloids. A wide range of analytical techniques has been used to clarify the mechanisms of these protein-misfolding processes, in the hope of developing effective therapeutic treatment. Most of these studies have relied heavily on conventional methods of protein characterization, notably circular dichroism spectroscopy, thioflavin T fluorescence, transmission electron microscopy, and atomic force microscopy, which are particularly suitable for monitoring later-stage aggregate formation. Although electrochemical methods of protein detection have existed for some time, they have only recently gained prominence as a powerful tool for studying the early stages of protein aggregation during which the more toxic soluble amyloid species form. Electrochemical detection methods include direct detection of intrinsic redox-active amino acid residues, protein-catalyzed hydrogen evolution, use of extrinsic ?-sheet binding mediators, and impedance spectroscopy. In this review, we evaluate the use of electrochemistry for study of protein aggregation related to neurodegenerative disorders. PMID:23529415

Veloso, Anthony; Kerman, Kagan

2013-03-26

182

Non-enzymatic electrochemical glucose sensor based on platinum nanoflowers supported on graphene oxide.  

PubMed

A non-enzymatic electrochemical method was developed for glucose detection using a glassy carbon electrode modified with platinum nanoflowers supported on graphene oxide (PtNFs-GO). PtNFs-GO was synthesized using a nontoxic, rapid, one-pot and template-free method. Low-cost, green solvent ethanol acted as the reductant, and the advanced and effective 2D carbon material-GO nanosheet acted as the stabilizing material. Their morphologies were characterized using transmission electron microscopy. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards glucose in neutral media. The modified electrode exhibited strong and sensitive amperometric responses to glucose even in the presence of a high concentration of chloride ions. The response time was within 5s. The interference effects from ascorbic acid and uric acid were comparatively small when operated at suitable potential. Under optimal detection potential (0.47 V with a saturated calomel reference electrode) the PtNFs-GO modified electrode performed a current response towards glucose at a broad concentration range from 2 ?M to 20.3mM. Two linear regions could be observed at 2 ?M to 10.3mM with a sensitivity of 1.26 ?A mM(-1)cm(-2) (correlation coefficient 0.9968), and at 10.3mM to 20.3mM with a sensitivity of 0.64 ?A mM(-1)cm(-2)(correlation coefficient 0.9969). The LOD of 2 ?M was lower than many non-enzymatic electrochemical glucose sensors. The modified electrode was also applied to the determination of glucose in glucose injection solutions, and the satisfactory results obtained indicated that it was promising for the development of a novel non-enzymatic electrochemical glucose sensor. PMID:23598034

Wu, Geng-huang; Song, Xin-hong; Wu, Yan-fan; Chen, Xiao-mei; Luo, Feng; Chen, Xi

2012-10-27

183

Electrochemical oxidation of stabilized landfill leachate on DSA electrodes.  

PubMed

The electrochemical oxidation of stabilized landfill leachate with 2960 mg L(-1) chemical oxygen demand (COD) over a Ti/IrO(2)-RuO(2) anode was investigated in the presence of HClO(4) as the supporting electrolyte. Emphasis was given on the effect of electrolysis time (up to 240 min) and temperature (30, 60 and 80°C), current density (8, 16 and 32 mA cm(-2)), initial effluent's pH (0.25, 3, 5 and 6), HClO(4) concentration (0.25 and 1M) and the addition of NaCl (20 and 100mM) or Na(2)SO(4) (20mM) as source of extra electrogenerated oxidants on performance; the latter was evaluated regarding COD, total carbon (TC), total phenols (TPh) and color removal. Moreover, the anode was studied by scanning electron microscopy and cyclic voltammetry. The main parameters affecting the process were the effluent's pH and the addition of salts. Treatment for 240 min at 32 mA cm(-2) current density, 80°C and the pH adjusted from its inherent value of 0.25 (i.e. after the addition of HClO(4)) to 3 yielded 90% COD, 65% TC and complete color and TPh removal at an electricity consumption of 35 kWh kg(-1) COD removed. Comparable performance (i.e. 75% COD reduction) could be achieved without pH adjustment but with the addition of 100mM NaCl consuming 20 kWh kg(-1) COD removed. PMID:21497996

Turro, Elisabetta; Giannis, Apostolos; Cossu, Raffaello; Gidarakos, Evangelos; Mantzavinos, Dionissios; Katsaounis, Alexandros

2011-03-29

184

Development of an Advanced Electrochemical DNA Biosensor for Bacterial Pathogen Detection  

PubMed Central

Electrochemical sensors have the capacity for rapid and accurate detection of a wide variety of target molecules in biological fluids. We have developed an electrochemical sensor assay involving hybridization of bacterial 16S rRNA to fluorescein-modified detector probes and to biotin-modified capture probes anchored to the sensor surface. Signal is generated by an oxidation-reduction current produced by the action of horseradish peroxidase conjugated to an anti-fluorescein monoclonal Fab. A previous study found that this electrochemical sensor strategy could identify uropathogens in clinical urine specimens. To improve assay sensitivity, we examined the key steps that affect the current amplitude of the electrochemical signal. Efficient lysis and release of 16S rRNA from both gram-negative and -positive bacteria was achieved with an initial treatment with Triton X-100 and lysozyme followed by alkaline lysis, resulting in a 12-fold increase in electrochemical signal compared with alkaline lysis alone. The distance in nucleotides between the target hybridization sites of the detector and capture probes and the location of fluorescein modification on the detector probe contributed to a 23-fold change in signal intensity. These results demonstrate the importance of target-probe and probe-probe interactions in the detection of bacterial 16S rRNA using an electrochemical DNA sensor approach.

Liao, Joseph C.; Mastali, Mitra; Li, Yang; Gau, Vincent; Suchard, Marc A.; Babbitt, Jane; Gornbein, Jeffrey; Landaw, Elliot M.; McCabe, Edward R.B.; Churchill, Bernard M.; Haake, David A.

2007-01-01

185

Advanced Launch System Advanced Development Oxidizer Turbopump Program: Technical Implementation Plan.  

National Technical Information Service (NTIS)

The Advanced Launch Systems (ALS) Advanced Development Oxidizer Turbopump Program has designed, fabricated and demonstrated a low cost, highly reliable oxidizer turbopump for the Space Transportation Engine that minimizes the recurring cost for the ALS en...

F. Ferlita

1989-01-01

186

Optimization for removal of ruthenium from nitric acid solution by volatilizing with electrochemical oxidation  

Microsoft Academic Search

Ruthenium is a major fission product element among the platinum group elements (PGEs) in high-level liquid waste (HLLW). Ru tetra-oxide, RuO4, has high vapor pressure, which is high enough to be run off from its solution even at room temperature. Electrochemical oxidation method, to oxidize nitrosyl ruthenium to the tetra-oxide and then to remove ruthenium from liquid phase to gas

Soichi Sato; Noboru Endo; Kazuhito Fukuda; Yasuji Morita

2012-01-01

187

Electrochemical oxidation of 2-naphthol with in situ electrogenerated active chlorine  

Microsoft Academic Search

The electrochemical oxidation of 2-naphthol mediated by active chlorine electrogenerated in situ on a Ti–Ru–Sn ternary oxide has been studied by galvanostatic electrolysis under different experimental conditions. Measurements of chemical oxygen demand (COD), HPLC and GC analyses have been used to follow the oxidation. In the absence of NaCl, only a small fraction of 2-naphthol was oxidized by direct electrolysis,

M Panizza; G Cerisola

2003-01-01

188

Studies on electrochemical recovery of silver from simulated waste water from Ag(II)\\/Ag(I) based mediated electrochemical oxidation process  

Microsoft Academic Search

In the Ag(II)\\/Ag(I) based mediated electrochemical oxidation (MEO) process, the spent waste from the electrochemical cell, which is integrated with the scrubber columns, contains high concentrations of precious silver as dissolved ions in both the anolyte and the catholyte. This work presents an electrochemical developmental study for the recovery of silver from simulated waste water from Ag(II)\\/Ag(I) based MEO process.

K. Chandrasekara Pillai; Sang Joon Chung; Il-Shik Moon

2008-01-01

189

Novel imazethapyr detoxification applying advanced oxidation processes.  

PubMed

Different degradation methods have been applied to assess the suitability of advanced oxidation process (AOPs) to promote mineralization of imazethapyr [(RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid], a widely used imidazolinone class herbicide, the persistence of which has been demonstrated in surface and ground waters destined to human uses. Independent of the oxidation process assessed, the decomposition of imazethapyr always followed a pseudo-first order kinetic. The direct UV-irradiation (UV) of the herbicide as well as its oxidation with ozone (O?), and hydrogen peroxide tied to UV-irradiation (H?O?/UV) were sufficiently slow to permit the identification of intermediate products, the formation pathway of which has been proposed. Ozonation joined to UV-irradiation (O?/UV), ozonation joined to titanium dioxide photo-catalysis (TiO?/UV+O?), sole photo-catalysis (TiO?/UV), and photo-catalysis reinforced with hydrogen peroxide-oxidation (TiO?/UV+H?O?) were characterized by a faster degradation and rapid formation of a lot of small molecules, which were quickly degraded to complete mineralization. The most effective oxidation methods were those using titanium dioxide photo-catalysis enhanced either by ozonation or hydrogen peroxide. Most of all, these last processes were useful to avoid the development of dangerous by-products. PMID:21726140

Stathis, Ioannis; Hela, Dimitra G; Scrano, Laura; Lelario, Filomena; Emanuele, Lucia; Bufo, Sabino A

2011-01-01

190

In situ transmission electron microscopy observations of electrochemical oxidation of Li2O2.  

PubMed

In this Letter, we report the first in situ transmission electron microscopy observation of electrochemical oxidation of Li2O2, providing insights into the rate limiting processes that govern charge in Li-O2 cells. In these studies, oxidation of electrochemically formed Li2O2 particles, supported on multiwall carbon nanotutubes (MWCNTs), was found to occur preferentially at the MWCNT/Li2O2 interface, suggesting that electron transport in Li2O2 ultimately limits the oxidation kinetics at high rates or overpotentials. PMID:23586606

Zhong, Li; Mitchell, Robert R; Liu, Yang; Gallant, Betar M; Thompson, Carl V; Huang, Jian Yu; Mao, Scott X; Shao-Horn, Yang

2013-04-25

191

Influence of Experimental Parameters in the Treatment of Distillery Effluent by Electrochemical Oxidation  

Microsoft Academic Search

The electrochemical oxidation of distillery effluent was studied in a batch reactor in the presence of supporting electrolyte NaCl using Mixed Metal Oxide (MMO) electrode. The effect of operating parameters such as current density, initial pH, and initial electrolyte concentration on the percentage of Chemical Oxygen Demand (COD) removal, power consumption, and current efficiency were studied. The maximum percentage removal

P. Asaithambi; Lakshminarayana Garlanka; N. Anantharaman; Manickam Matheswaran

2012-01-01

192

Influence of Experimental Parameters in the Treatment of Distillery Effluent by Electrochemical Oxidation  

Microsoft Academic Search

The electrochemical oxidation of distillery effluent was studied in a batch reactor in the presence of supporting electrolyte NaCl using Mixed Metal Oxide (MMO) electrode. The effect of operating parameters such as current density, initial pH and initial electrolyte concentration on percentage of Chemical Oxygen Demand (COD) removal, power consumption and current efficiency were studied. The maximum percentage removal of

P. Asaithambi; Lakshminarayana Garlanka; N. Anantharaman; Manickam Matheswaran

2011-01-01

193

Electrochemical oxidation of phenolic wastes with boron-doped diamond anodes  

Microsoft Academic Search

The electrochemical oxidation of several phenolic aqueous wastes has been studied using a bench-scale plant with a single-compartment electrochemical flow cell. Boron-doped diamond materials were used as the anode. Complete mineralization of the waste was obtained in the treatment of phenols not substituted with chlorine or nitrogen. Chlorinated phenolic compounds were transformed into carbon dioxide; volatile organochlorinated compounds and nitro-substituted

P. Cañizares; J. Lobato; R. Paz; M. A. Rodrigo; C. Sáez

2005-01-01

194

Electrochemical impedance spectroscopy studies of lithium diffusion in doped manganese oxide  

Microsoft Academic Search

Cathode performance is critical to lithium ion rechargeable battery performance; effects of doping lithium manganese oxide cathode materials on cathode performance are being investigated. In this paper, Li diffusion in Al-doped LiMnâOâ was studied and found to be controlled by the quantity of Al dopant. Electrochemical cycling was conducted at 0.5mA\\/cmâ; electrochemical impedance spectra were taken at open circuit potential,

B. J. Johnson; D. H. Doughty; J. A. Voigt; T. J. Boyle

1996-01-01

195

Synthesis of reduced graphene oxide and its electrochemical sensing of 4-nitrophenol  

NASA Astrophysics Data System (ADS)

Reduced graphene oxide (RGO) nanosheets were synthesized by chemical reduction followed by Hummer's method. The synthesized RGO nanosheets were characterized by XRD, HR-TEM and FT-IR spectroscopy. Cyclic voltammetry (CV) was used to study the electrochemical sensing of 4-nitrophenol (4-NP). The as synthesized RGO nanosheets modified glassy carbon electrode (RGO/GCE) showed a good electrochemical sensing property when compared with bare GCE.

Giribabu, K.; Suresh, R.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

2013-02-01

196

Electrochemical oxidation of several chlorophenols on diamond electrodes Part I. Reaction mechanism  

Microsoft Academic Search

The electrochemical oxidation of 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol aqueous wastes using boron-doped diamond electrodes was studied. This treatment led to complete mineralization of the wastes regardless of the operating conditions. A simple mechanistic model is consistent with the voltammetric and electrolysis results. According to this model, the electrochemical treatment of chlorophenol aqueous wastes involves the anodic and cathodic release of

P. Cañizares; J. García-Gómez; C. Sáez; M. A. Rodrigo

2003-01-01

197

Electrochemical oxidation of pyrite (FeS 2) in aqueous electrolytes  

Microsoft Academic Search

Electrochemical oxidation of pyrite (FeS2) in aqueous electrolytes has been investigated using electrochemical techniques, in situ Fourier transform infrared spectroscopy (FTIR), ex situ X-ray photoelectron spectroscopy (XPS) and ion chromatography (IC). The results show that when pyrite is polarised in the potential region of ?0.35 to 0.25 V versus SCE in 1 M HCl at sweep rates ?30 mV s?1,

G. H. Kelsall; Q. Yin; D. J. Vaughan; K. E. R. England; N. P. Brandon

1999-01-01

198

Studies on room temperature electrochemical oxidation and its effect on the transport properties of TBCCO films  

NASA Astrophysics Data System (ADS)

A novel room temperature electrochemical process for the synthesis of single-phase Tl2Ba2Ca2Cu3O10 (TBCCO/Tl-2223) superconducting films has been developed. Electrochemical parameters were optimized by studying linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) for the deposition of Tl-Ba-Ca-Cu alloy at room temperature. The superconducting films of the TBCCO were obtained by two oxidation techniques. In the first technique, the electrodeposited Tl-Ba-Ca-Cu alloyed films were oxidized at various temperatures in flowing oxygen atmosphere. In the second technique, stoichiometric electrocrystallization to get Tl2Ba2Ca2Cu3O10 (Tl-2223) was completed by electrochemically intercalating oxygen species into Tl-Ba-Ca-Cu alloy at room temperature for various lengths of time. The oxygen content in the samples was varied by varying the electrochemical oxidation period, and the changes in the crystal structure, superconducting transition temperature (Tc) and critical current density (Jc) were recorded. The high temperature furnace oxidation technique was replaced by the room temperature electrochemical oxidation technique. The dependence of superconducting parameters on oxygen content is correlated with structure-property relations.

Shirage, P. M.; Shivagan, D. D.; Pawar, S. H.

2004-07-01

199

Nanoporous metals: fabrication strategies and advanced electrochemical applications in catalysis, sensing and energy systems.  

PubMed

Nanoporous metals, a representative type of nanostructured material, possess intriguing properties to generate enormously promising potentials for various important applications. In particular, with the advances of fabrication strategies, nanoporous metals with a variety of superior properties including unique pore structure, large specific surface area and high electrical conductivity have fuelled up great interests to explore their electrocatalytic properties and greatly extend their emerging applications in electrochemical sensing and energy systems. This tutorial review attempts to summarize the recent important progress towards the development of nanoporous metals, with special emphasis on fabrication methods and advanced electrochemical applications, such as electrocatalysts, chemical sensors and energy systems. Key scientific issues and prospective directions of research are also discussed. PMID:22975622

Zhang, Jintao; Li, Chang Ming

2012-09-13

200

Development of Advanced Electrochemical Sensors for DNA Detection at the Point of Care  

NASA Astrophysics Data System (ADS)

In the post-genomic era, ever-advancing capabilities in DNA detection and analysis have become vital to the detection of infectious diseases and the diagnosis of genetic abnormalities and inheritable diseases. The benefit of such capabilities, however, has yet to reach patients outside of centralized facilities. There thus exists an increasing need to decentralize DNA detection methods and to administer such diagnostics at the "point of care." Electrochemical-based DNA sensors present a compelling approach, but have yet to deliver satisfactory sensitivity, specificity, miniaturization, and real-time monitoring capability to meet the demand of point-of-care diagnostics. Motivated by their potential and their current limitations, in this dissertation, we present a series of strategies that we have undertaken in order to address the key shortcomings of electrochemical DNA sensors and advance them toward point-of-care applications. First, we report a single-step, single reagent, label-free, isothermal electrochemical DNA sensor based on the phenomenon of enzyme catalyzed target recycling amplification. Using this technique, we achieve improved detection limit in comparison to hybridization-based sensors without amplification. We also demonstrate greater than 16-fold amplification of signal at low target concentrations. Next, we present a novel electrochemical DNA sensor that detects single-nucleotide mismatched targets with unprecedented "polarity-switching" responses. This "bipolar" sensor employs a surface-bound and redox-modified (methylene blue) DNA probe architecture, and outputs a decreased Faradaic current when hybridized to a perfectly matched (PM) target, but conversely reports an increased Faradaic current when hybridized to a single-base mismatched (SM) target. Third, we describe the microfluidic electrochemical dynamic allele specific hybridization (microE-DASH) platform for versatile and rapid detection of single-nucleotide polymorphisms. Implementing electrochemical-based melting curve analysis within the microfluidic device, this platform directly detects PCR amplicon-like targets and distinguishes perfectly matched target from single-base mismatched target and heterozygote combination of both targets in 20 minutes. Finally, we present the microfluidic electrochemical quantitative loop-mediated isothermal amplification (MEQ-LAMP) platform for rapid, sensitive, and quantitative detection of pathogen genomic DNA at the point of care. DNA amplification is electrochemically monitored in real time within a monolithic microfluidic device, enabling the detection of as few as 16 copies of Salmonella genomic DNA via a single-step process in under an hour.

Hsieh, Kuangwen

201

Lipid Advanced Glycosylation: Pathway for Lipid Oxidation in vivo  

Microsoft Academic Search

To address potential mechanisms for oxidative modification of lipids in vivo, we investigated the possibility that phospholipids react directly with glucose to form advanced glycosylation end products (AGEs) that then initiate lipid oxidation. Phospholipid-linked AGEs formed readily in vitro, mimicking the absorbance, fluorescence, and immunochemical properties of AGEs that result from advanced glycosylation of proteins. Oxidation of unsaturated fatty acid

Richard Bucala; Zenji Makita; Theodor Koschinsky; Anthony Cerami; Helen Vlassara

1993-01-01

202

Electrochemical behavior of antioxidants: I. Mechanistic study on electrochemical oxidation of gallic acid in aqueous solutions at glassy-carbon electrode  

Microsoft Academic Search

Mechanism of electrochemical oxidation of gallic acid in aqueous phosphate buffer solutions of different pH’s was studied at glassy-carbon electrode. The study was performed using cyclic, convolution–deconvolution sweep voltammetry, chronoamperometry and chronocoulometry. It gives two irreversible diffusion-controlled cyclic voltammetric waves at the entire range of pH. The electrochemical oxidation mechanism was proposed to be an ECEC-first order mechanism in which

Refat Abdel-Hamid; Emad F. Newair

2011-01-01

203

Influence of anode material on the electrochemical oxidation of 2-naphthol  

Microsoft Academic Search

The electrochemical oxidation of 2-naphthol has been studied by galvanostatic electrolysis, using a range of electrode materials such as lead dioxide, boron-doped diamond (BDD) and Ti–Ru–Sn ternary oxide anodes. The influence of some operating parameters, such as current density, flow-rate and chloride concentration on naphthol oxidation has been investigated in order to find the optimum experimental conditions. Measurements of chemical

M. Panizza; G. Cerisola

2004-01-01

204

Detailed parameter study on the mechanisms in electrochemical oxidation of p-nitrosodimethylaniline in chloride electrolyte  

Microsoft Academic Search

This paper studies the use of p-nitrosodimethylaniline (RNO) as a selective probe compound for hydroxyl radical detection in electrochemical oxidation studies. In the applied recirculation experimental setup with a Ti\\/Pt90-Ir10 anode, oxidation of RNO was found in both inert sulphate, phosphate, and nitrate electrolytes and electroactive chloride electrolytes, where the rate of oxidation was dramatically enhanced due to the indirect

205

A Comparative study on oxidation of disperse dyes by electrochemical process, ozone, hypochlorite and fenton reagent  

Microsoft Academic Search

The results of an experimental study on the destruction of disperse dyes by chemical oxidation using ozone, hypochlorite and Fenton reagent (H2O2+Fe2+) are compared with the data obtained by electrochemical oxidation. While the results obtained during hypochlorite oxidation were not satisfactory (only 35% reduction of colour was achieved at a dose of 6gdm?3), ozonation enabled colour to be reduced by

Lidia Szpyrkowicz; Claudia Juzzolino; Santosh N Kaul

2001-01-01

206

Photocatalytic oxidation of cyanide on TiO 2: An electrochemical approach  

Microsoft Academic Search

Photocatalytic oxidation of cyanide on TiO2 was studied by means of voltammetry, linear polarization resistance and Tafel polarization using TiO2–carbon paste electrodes (TiO2–CPEs). In all cases, a positive effect with UV–vis illumination on the oxidation current (i.e. oxidation rate) was observed, showing the convenience of this type of electrodes for the electrochemical evaluation of powdered semiconductor photocatalysts. Voltammetric results indicated

J. A. Pedraza-Avella; P. Acevedo-Peña; J. E. Pedraza-Rosas

2008-01-01

207

Pilot treatment of olive pomace leachate by vertical-flow constructed wetland and electrochemical oxidation: An efficient hybrid process  

Microsoft Academic Search

A hybrid process comprising biological degradation in a vertical-flow constructed wetland (CW) and electrochemical oxidation over boron-doped diamond electrodes to decolorize, mineralize and detoxify a leachate from olive pomace processing (OPL) was investigated. Two alternative treatment schemes were compared: According to the first treatment scheme, OPL was treated by electrochemical oxidation followed by treatment in a constructed wetland pilot unit

Petros Grafias; Nikolaos P. Xekoukoulotakis; Dionissios Mantzavinos; Evan Diamadopoulos

2010-01-01

208

Influence of Heat-Treatment and Physicochemical Properties on the Electrochemical Oxidation of Carbon Blacks in Phosphoric Acid.  

National Technical Information Service (NTIS)

Studies on the electrochemical oxidation of carbon blacks in concentrated phosphoric acid at 135 to 160 exp 0 C will be reviewed. The objective of the paper is to provide some understanding of the electrochemical-oxidation mechanism and the influence of p...

K. Kinoshita

1983-01-01

209

Electrochemical oxidation of bisphenol A. Application to the removal of bisphenol A using a carbon fiber electrode  

Microsoft Academic Search

The electrochemical behavior of bisphenol A was investigated by voltammetric techniques. The electrochemical oxidation of bisphenol A led to the inactivation of the glassy carbon electrode as the result of the deposition of the electropolymerized films. Although phenolate is oxidized more easily than the neutral phenol, an electropolymerized film of bisphenol A was formed in neutral media rather than in

Hideki Kuramitz; Yohsuke Nakata; Mikio Kawasaki; Shunitz Tanaka

2001-01-01

210

Theoretical calculations on dipyridamole structure allow to explain experimental properties associated to electrochemical oxidation and protonation  

NASA Astrophysics Data System (ADS)

PM3 calculations of charge distributions for dipyridamole (DIP) in the neutral, single- and double-ionized states allowed to estimate the first and second ionization potentials. Results are compared with electrochemical oxidation, a sequential two-step process. Single ionization produces a cation radical, the electron being removed from the nitrogen atoms in the substituent positions 2,4,6,8 with participation of the carbons in the pyrimido-pyrimidine ring. Protonation of one of the nitrogens is allowed energetically while a second protonation is forbidden due to the high energy required. Our calculations allow to explain some interesting experimental results related to electrochemical oxidation and protonation of the drug.

Alves, C. N.; Castilho, M.; Mazo, L. H.; Tabak, M.; da Silva, A. B. F.

2001-11-01

211

Local electrochemical oxidation/reduction: First step towards a new lithography?  

NASA Astrophysics Data System (ADS)

We have recently shown that it is possible to electrochemically oxidize c-axis La2CuO4 thin films grown on different substrates. The electrochemical oxidation was subsequently performed on a local scale, i.e. oxygen-rich regions were induced in an otherwise oxygen deficient matrix. This extra oxygen created superconducting regions in the insulating matrix. This new lithographic technique does not require the addition or removal of large amounts of material, nor does it induce significant height differences.

Locquet, J.-P.

1996-05-01

212

Electrochemical oxidation of wine polyphenols in the presence of sulfur dioxide.  

PubMed

Electrochemical oxidation of three representative wine polyphenols (catechin, caffeic acid, and quercetin) in the presence of sulfur dioxide in a model wine solution (pH = 3.3) was investigated. The oxidation was undertaken using chronoamperometry at a rotating glassy carbon rod electrode, and the reaction products were characterized by HPLC-MS. The mechanism of electrochemical oxidation of polyphenols in the presence of sulfur dioxide was proposed to be an ECEC mechanism. The polyphenols first underwent a one-electron oxidation to a semiquinone radical, which can be reduced back to the original polyphenol by sulfur dioxide, or further oxidized to the quinone form. In the cases of caffeic acid and catechin, the quinone combined with sulfur dioxide and produced new derivatives. The quercetin quinone underwent further chemical transformations, producing several new compounds. The proposed mechanisms were confirmed by digital simulation of cyclic voltammograms. PMID:23692398

Makhotkina, Olga; Kilmartin, Paul A

2013-06-03

213

Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products.  

PubMed

Electrochemical oxidation of the isoquinoline alkaloid berberine in aqueous medium was studied by cyclic and differential pulse voltammetry at a glassy carbon electrode (GCE). Two anodic peaks of the quaternary form of berberine were observed at +1.2V and +1.4V (vs. SCE) in acidic and neutral solutions. When the anodic polarization exceeded the value of +1.1 V, the redox active film is formed on the GCE surface. The formation of adsorbed film was well-documented by quasireversible redox couple at +0.25 V which was studied in redox cycling experiments. In alkaline medium, a new anodic peak at +0.5 V appeared due to oxidation of berberine pseudobase to 8-oxoberberine. Solutions of berberine at different pH were subjected to controlled potential electrolysis on platinum gauze electrode and analyzed using liquid chromatography (HPLC) equipped with electrospray ionization/quadrupole time-of-flight mass spectrometry. The main water soluble monomeric product of berberine oxidation under physiological-near experimental conditions, OP1, was identified as demethyleneberberine cation (2,3-dihydroxy-9,10-dimethoxy-5,6-dihydroisoquinolino[3,2-a]isoquinolin-7-ium). PMID:21963270

Skopalová, Jana; Vacek, Jan; Papoušková, Barbora; Jirovský, David; Maier, Vít?zslav; Ranc, Václav

2011-09-10

214

ADVANCED OXIDATION TECHNOLOGIES FOR THE TREATMENT OF CONTAMINATED GROUNDWATER  

EPA Science Inventory

This paper presents information on two pilot-field applications of advanced oxidation technologies for contaminated groundwater with organics. he two UV/oxidation technologies were developed by Ultrox International of Santa Ana, California and Peroxidation Systems, Inc. of Tucson...

215

ADVANCED OXIDATION TECHNOLOGIES FOR THE TREATMENT OF CONTAMINATED GROUNDWATER  

EPA Science Inventory

This paper presents information on two pilot-field appliations of advanced oxidation technologies for contaminated groundwater with organis. The two UV/oxidation technologies were developed by Ultrox International of Santa Ana, California and Peroxidatrion Systems, Inc. of Tucso...

216

Ultra-thin films on transparent conductor oxides for the development of spectro-electrochemical transducers  

NASA Astrophysics Data System (ADS)

Transparent C, Au and Pt films with thickness in the 5-10 nm range have been deposited by a DC magnetron sputtering system on commercial ITO (indium tin oxide) coated glass substrate for evaluation as electrode of spectro-electrochemical transducer. The transmission, over the investigated spectral range, is superior to 55% with the best transmission values obtained for C films (higher than 80%). The deposited films have been characterized by AFM, XPS and electrochemical methods. Results showed a low roughness, improved in comparison with uncoated electrodes. Electrochemical properties of the Au and Pt films evidenced a metallic behavior, which allowed qualifying them as conductive optically transparent electrodes for spectro-electrochemical devices.

Grigore, E.; Delacôte, C.; Thobie-Gautier, C.; Boujtita, M.; Tessier, P. Y.

2013-07-01

217

Mediated electrochemical oxidation of organic wastes without electrode separators  

DOEpatents

An electrochemical cell/electrolyte/mediator combination is described for the efficient destruction of organic contaminants using metal salt mediators in a sulfuric acid electrolyte, wherein the electrodes and mediator are chosen such that hydrogen gas is produced at the cathode and no cell membrane is required. 3 figs.

Farmer, J.C.; Wang, F.T.; Hickman, R.G.; Lewis, P.R.

1996-05-14

218

Mediated electrochemical oxidation of organic wastes without electrode separators  

DOEpatents

An electrochemical cell/electrolyte/mediator combination for the efficient destruction of organic contaminants using metal salt mediators in a sulfuric acid electrolyte, wherein the electrodes and mediator are chosen such that hydrogen gas is produced at the cathode and no cell membrane is required.

Farmer, Joseph C. (Newtown, PA); Wang, Francis T. (Danville, CA); Hickman, Robert G. (Livermore, CA); Lewis, Patricia R. (Livermore, CA)

1996-01-01

219

Application of advanced oxidation processes for TNT removal: A review.  

PubMed

Nowadays, there are increasingly stringent regulations requiring drastic treatment of 2,4,6-trinitrotoluene (TNT) contaminated waters to generate treated waters which could be easily reused or released into the environment without any harmful effects. TNT is among the most highly suspected explosive compounds that interfere with groundwater system due to its high toxicity and low biodegradability. The present work is an overview of the literature on TNT removal from polluted waters and soils and, more particularly, its treatability by advanced oxidation processes (AOPs). Among the remediation technologies, AOPs constitute a promising technology for the treatment of wastewaters containing non-easily biodegradable organic compounds. Data concerning the degradation of TNT reported during the period 1990-2009 are evaluated in this review. Among the AOPs, the following techniques are successively debated: processes based on hydrogen peroxide (H(2)O(2)+UV, Fenton, photo-Fenton and Fenton-like processes), photocatalysis, processes based on ozone (O(3), O(3)+UV) and electrochemical processes. Kinetic constants related to TNT degradation and the different mechanistic degradation pathways are discussed. Possible future treatment strategies, such as, coupling AOP with biological treatment is also considered as a mean to improve TNT remediation efficiency and kinetic. PMID:20347218

Ayoub, Kaidar; van Hullebusch, Eric D; Cassir, Michel; Bermond, Alain

2010-02-18

220

Mediated electrochemical oxidation process: Electrooxidation of cerium(III) to cerium(IV) in nitric acid medium and a study on phenol degradation by cerium(IV) oxidant  

Microsoft Academic Search

Cerium(III) in nitric acid medium was oxidized electrochemically using a flow type electrochemical cell fabricated in our laboratory. The variation of applied cell current, temperature and the concentration of the electrolyte were studied to determine the oxidation efficiency of Ce(III) in the electrochemical cell. The conversion yield of cerium(IV) in nitric acid was 97% in a short duration of 90min.

Subramanian Balaji; Sang Joon Chung; Ramesh Thiruvenkatachari; Il Shik Moon

2007-01-01

221

Synthesis and characterization of a nanocomposite of goethite nanorods and reduced graphene oxide for electrochemical capacitors  

SciTech Connect

We report a one-step synthesis of a nanocomposite of goethite ({alpha}-FeOOH) nanorods and reduced graphene oxide (RGO) using a solution method in which ferrous cations serve as a reducing agent of graphite oxide (GO) to graphene and a precursor to grow goethite nanorods. As-prepared goethite nanorods have an average length of 200 nm and a diameter of 30 nm and are densely attached on both sides of the RGO sheets. The electrochemical properties of the nanocomposite were characterized by cyclic voltammetry (CV) and chronopotentiometry (CP) charge-discharge tests. The results showed that goethite/RGO composites have a high electrochemical capacitance of 165.5 F g{sup -1} with an excellent recycling capability making the material promising for electrochemical capacitors. - Graphical abstract: The reduced graphene oxide sheets are decorated with goethite nanorods. The as-prepared composite exhibits a high electrochemical capacitance with good recycling capability, which is promising for supercapacitor applications. Higlights: Black-Right-Pointing-Pointer Ferrous ions act as reductant of graphite oxide and precursor of goethite nanorods. Black-Right-Pointing-Pointer Goethite nanorods are attached on both sides of the reduced graphene oxide sheets. Black-Right-Pointing-Pointer Composite exhibits a high specific capacitance and a good recycling capability. Black-Right-Pointing-Pointer Composite is promising for supercapacitor applications.

Shou Qingliang [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Cheng Jipeng, E-mail: chengjp@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang Li, E-mail: lizhang@ethz.ch [Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092 Zurich (Switzerland); Nelson, Bradley J. [Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092 Zurich (Switzerland); Zhang Xiaobin [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2012-01-15

222

Characterization of Schottky barrier diodes fabricated from electrochemical oxidation of ? phase brass  

NASA Astrophysics Data System (ADS)

By careful selection of chloride ion concentration in aqueous sodium chloride, electrochemical oxidation of ? phase brass is shown to permit fabrication of either p-type copper (I) oxide/metal or n-type zinc oxide/metal Schottky barrier diodes. X-ray photoelectron and Auger electron spectroscopies provide evidence that barrier formation and rectifying qualities depend on the relative surface abundance of copper (I) oxide and zinc oxide. X-ray diffraction of the resulting diodes shows polycrystalline oxides embedded in amorphous oxidation products that have a lower relative abundance than the diode forming oxide. Conventional I/V characteristics of these diodes show good rectifying qualities. When neither of the oxides dominate, the semiconductor/metal junction displays an absence of rectification.

Bond, John W.

2011-04-01

223

Nanostructured metal oxide-based materials as advanced anodes for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

The search for new electrode materials for lithium-ion batteries (LIBs) has been an important way to satisfy the ever-growing demands for better performance with higher energy/power densities, improved safety and longer cycle life. Nanostructured metal oxides exhibit good electrochemical properties, and they are regarded as promising anode materials for high-performance LIBs. In this feature article, we will focus on three different categories of metal oxides with distinct lithium storage mechanisms: tin dioxide (SnO2), which utilizes alloying/dealloying processes to reversibly store/release lithium ions during charge/discharge; titanium dioxide (TiO2), where lithium ions are inserted/deinserted into/out of the TiO2 crystal framework; and transition metal oxides including iron oxide and cobalt oxide, which react with lithium ions via an unusual conversion reaction. For all three systems, we will emphasize that creating nanomaterials with unique structures could effectively improve the lithium storage properties of these metal oxides. We will also highlight that the lithium storage capability can be further enhanced through designing advanced nanocomposite materials containing metal oxides and other carbonaceous supports. By providing such a rather systematic survey, we aim to stress the importance of proper nanostructuring and advanced compositing that would result in improved physicochemical properties of metal oxides, thus making them promising negative electrodes for next-generation LIBs.

Wu, Hao Bin; Chen, Jun Song; Hng, Huey Hoon; Wen (David) Lou, Xiong

2012-03-01

224

Kinetics of simazine advanced oxidation in water.  

PubMed

Comparison of the effects and kinetics of UV photolysis and four advanced oxidation systems (ozone, ozone/hydrogen peroxide, ozone/UV radiation and UV radiation/hydrogen peroxide) for the removal of simazine from water has been investigated. At the conditions applied, the order of reactivity was ozone < ozone/hydrogen peroxide < UV radiation < ozone/UV radiation and UV radiation/hydrogen peroxide. Rate constants of the reactions between ozone and simazine and hydroxyl radical and simazine were found to be 8.7 M-1s-1 and 2.1 x 10(9) M-1s-1, respectively. Also, a quantum yield of 0.06 mol.photon-1 was found for simazine at 254 nm UV radiation. The high value of the quantum yield corroborated the importance of the direct photolysis process. Percentage contributions of direct reaction with ozone, reaction with hydroxyl radicals and direct photolysis were also quantified. PMID:10874621

Beltrán, F J; García-Araya, J F; Rivas, J; Alvarez, P M; Rodríguez, E

2000-07-01

225

Highly efficient and energy-saving sectional treatment of landfill leachate with a synergistic system of biochemical treatment and electrochemical oxidation on a boron-doped diamond electrode  

Microsoft Academic Search

In this paper, a synergistic combination of the biochemical treatment and electrochemical oxidation (SBEO) of landfill leachate with sectional treatment on a boron-doped diamond (BDD) electrode is proposed. The first stage involves the synergistic system of biochemical treatment and electrochemical oxidation. Then, the second stage is followed by individual biochemical treatment. Comparisons among the SBEO, electrochemical oxidation, biochemical treatment and

Guohua Zhao; Yaning Pang; Lei Liu; Junxia Gao; Baoying Lv

2010-01-01

226

EFFECT OF X-RADIATION ON THE ELECTROCHEMICAL OXIDATION OF FORMIC ACID ON Pt ELECTRODE  

Microsoft Academic Search

Many electrochemical oxidation reactions are kinetically inhibited on Pt ; anodes and necessitate further work for the complete understanding of the ; inhibiting mechanism in order to eliminate it. In view of the known effect of ; ionizing radiation on dilute aqueous solutions, resulting in the formation of ; radiolytic products, such as Hâ and HâOâ together with short-; lived

P. I. Dolin; D. V. Kokoulina; S. A. Brusentseva; S. A. Kabakchi

1962-01-01

227

Direct electrodeposition of reduced graphene oxide on glassy carbon electrode and its electrochemical application  

Microsoft Academic Search

Graphene nanosheets were directly deposited onto a glassy carbon electrode through cyclic voltammetric reduction of a graphene oxide colloidal solution. The resulting electrodes were characterized by electrochemical methods and scanning electron microscopy. The application of the graphene modified electrodes in simultaneous determination of hydroquinone and catechol was investigated.

Liuyun Chen; Yanhong Tang; Ke Wang; Chengbin Liu; Shenglian Luo

2011-01-01

228

Unexpected Redox Rectification by an Electrochemically Prepared Iridium Oxide Electrode/Aqueous Acid Interface.  

National Technical Information Service (NTIS)

In highly acidic aqueous solutions, electrochemically prepared iridium oxide films behave as steady-state insulators and transient rectifiers towards the Ru(NH3)6 3+/2+ redox couple. In less acidic solutions the films show only partial transient rectifica...

C. S. Johnson J. T. Hupp

1992-01-01

229

Electrochemical performance of polypyrrole\\/silver vanadium oxide composite cathodes in lithium primary batteries  

Microsoft Academic Search

Polypyrrole (PPy)\\/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge

Yogesh K. Anguchamy; Jong-Won Lee; Branko N. Popov

2008-01-01

230

High-Volumetric Performance Aligned Nano-Porous Microwave Exfoliated Graphite Oxide-based Electrochemical Capacitors.  

PubMed

Ultra-high volumetric performance electrochemical double layer capacitors based on high density aligned nano-porous microwave exfoliated graphite oxide have been studied. Elimination of macro-, meso-, and larger micro-pores from electrodes and controlling the nano-morphology results in very high volumetric capacitance, energy, and power density values. PMID:23946189

Ghaffari, Mehdi; Zhou, Yue; Xu, Haiping; Lin, Minren; Kim, Tae Young; Ruoff, Rodney S; Zhang, Q M

2013-08-15

231

Electrochemical oxidation of o-aminophenol in aqueous acidic medium: formation of film and soluble products  

Microsoft Academic Search

The electrochemical oxidation of o-aminophenol (OAP) has been studied by cyclic voltammetry on platinum (Pt) and glassy carbon (GC) electrodes. Films formed on Pt exhibited a voltammetric response that is dependent on the final potential applied during the electropolymerization. Although a less electroactive film has been obtained on Pt electrodes cycled at higher potentials, modified GC electrodes showed a well-defined

D Gonçalves; R. C Faria; M Yonashiro; L. O. S Bulhões

2000-01-01

232

Synergistically enhanced electrochemical (ORR) activity of graphene oxide using boronic acid as an interlayer spacer.  

PubMed

Herein, boronic acid is incorporated into a graphene oxide (GO) structure in order to synthesise a graphene organic framework (GOF) with enhanced electrochemical performance. The results obtained indicate that the GOF favours a 4e(-) reduction pathway in the oxygen reduction reaction (ORR). PMID:24141877

Pourazadi, Ehsan; Haque, Enamul; Zhang, Weimin; Harris, Andrew T; Minett, Andrew I

2013-10-31

233

Electrochemical oxidation of aqueous phenol at a carbon black slurry electrode  

Microsoft Academic Search

The electrochemical oxidation of an aqueous phenol solution was studied via a novel process. Experiments were conducted by recirculating a slurry electrode made of the product to be treated (phenol) and a catalyst (carbon black) through a flow-by electrolyser with a vertical stack of perforated Ti\\/Pt electrodes. Both the capacity of high adsorption of organic compounds and gases and the

J. L. Boudenne; O. Cerclier; J. Galéa; E. Van der Vlist

1996-01-01

234

New effects in the kinetics of the electrochemical oxidation of silicon  

Microsoft Academic Search

The present work describes new effects in the kinetics of the electrochemical oxidation of silicon observed recently by the author. One is the observation of very large oscillations of anodic potential during anodization of silicon in H3PO4\\/HF electrolyte and another is the effect of externally applied mechanical stress onto the kinetics of the Si anodization in concentrated and diluted HF.

Vitali Parkhutik

2000-01-01

235

Electrochemical oxidation and detection of paeonol on modified electrode with acetylene black nanoparticles  

Microsoft Academic Search

With an aim to construct a sensing platform for the electrochemical detection of paeonol, we modified the glassy carbon electrode with acetylene black nanoparticle (AB). A sensitive oxidation peak of paeonol was observed with remarkably increased peak current on the modified electrode because the electrode has a big surface area due to three dimensional structure of AB nanoparticles. The optimization

Huajie Zhang; Miaomiao Gao; Xiaofeng Yang

2011-01-01

236

Chemical and electrochemical oxidation of C8-arylamine adducts of 2?-deoxyguanosine  

PubMed Central

The electrochemical and chemical oxidation of a series of C8-arylamine adducts of 2?-deoxyguanosine has been examined. The oxidations were found to be reversible by cyclic and square-wave voltammetry in both aqueous buffer and aprotic organic solvent. The mechanism of the oxidation in protic media was either one- or two-electron depending on the aryl group. The chemical oxidation resulted in guanidinohydantoin and spiroiminodihydantoin rearrangement products similar to those observed for 8-oxo-7,8-dihydro-2?-deoxyguanosine.

Stover, James S.; Ciobanu, Madalina; Cliffel, David E.; Rizzo, Carmelo J.

2008-01-01

237

Electrochemical oxidation of phenol for wastewater treatment using SnO 2 , anodes  

Microsoft Academic Search

The electrochemical oxidation of phenol for waste water treatment was studied on doped SnO2 anodes. Analysis of reaction intermediates and a carbon balance has shown that the main reaction is oxidation of phenol to CO2. This unexpected behaviour of the SnO2 anode is explained by a change of the chemical structure of the electrode surface during anodic polarization.

Ch. Comninellis; C. Pulgarin

1993-01-01

238

Kinetics of the electrochemical oxidation of organic compounds at BDD anodes: modelling of surface reactions  

Microsoft Academic Search

This paper presents the results of a numerical study of the kinetics of electrochemical oxidation of different organic substances\\u000a at boron doped diamond (BDD).\\u000a \\u000a It is well established that oxidation of organics at BDD anodes takes place in the potential region of oxygen evolution, through\\u000a reaction steps in which OH radicals are involved: these radicals can react with organic compounds

Michele Mascia; Annalisa Vacca; Simonetta Palmas; Anna Maria Polcaro

2007-01-01

239

Electrochemical treatment of dilute cyanide solutions containing zinc complexes by oxidation at carbon felt (Sigratherm)  

Microsoft Academic Search

The electrochemical oxidation of dilute solutions containing cyanide complexes of zinc using a carbon felt anode is described. The composition of the solution was determined using stability constants for particular complexes. The application of a GFA5 electrode enables the oxidation of cyanides (10 mmol dm-3) in 99.2% at 0.7 V and 30 C (1.5 Qt). Under these conditions, the electrical

A. Socha; E. Ku?mierek; E. Chrze?cija?ska

2002-01-01

240

Electrochemical investigation of polyhalide ion oxidation–reduction on carbon nanotube electrodes for redox flow batteries  

Microsoft Academic Search

Polyhalide ions, Br?\\/BrCl2-(ClBr2-), are an important redox couple for redox flow batteries. The oxidation–reduction behavior of polyhalide ions on carbon nanotube (CNT) electrodes has been investigated with cyclic voltammetry and electrochemical impedance spectroscopy. The onset oxidation potential of Br?\\/BrCl2-(ClBr2-) is negatively shifted by>100mV, and the redox current peaks are greatly enhanced on the CNT electrode compared with that on the

Yuyan Shao; Mark H. Engelhard; Yuehe Lin

2009-01-01

241

Enhanced electrochemical characteristics of lithium manganese oxide thin film cathodes for lithium-ion rechargeable microbatteries  

Microsoft Academic Search

Spinel LiMn2O4 (average oxidation state of Mn = 3.5) thin film has been introduced for a promising cathode of thin film lithium-ion microbatteries because of its advantages over other cathodes. Thus, many research groups have been investigating the thin film lithium manganese oxide cathode using several different techniques but only a few of them achieved acceptable electrochemical properties required for

Won-Seok Kim

2004-01-01

242

Destruction of EDTA by mediated electrochemical oxidation process: Monitoring by continuous CO 2 measurements  

Microsoft Academic Search

The mediated electrochemical oxidation (MEO) process with cerium(IV) in nitric acid as the oxidizing medium was employed for the destruction of ethylenediaminetetraacetic acid (EDTA) in batch and continuous feeding modes. A complete mineralization of EDTA to CO2 and water was achieved. The system parameters studied were the temperature (343, 353 and 368K), concentration of nitric acid (2, 3 and 4M),

S. Balaji; V. V. Kokovkin; S. J. Chung; I. S. Moon

2007-01-01

243

Boron-doped diamond electrodes for the electrochemical oxidation and cleavage of peptides.  

PubMed

Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy carbon (GC) electrodes for the electrochemical oxidation and cleavage of peptides. An optimal working potential of 2000 mV was chosen to ensure oxidation of peptides on BDD by electron transfer processes only. Oxidation by electrogenerated OH radicals took place above 2500 mV on BDD, which is undesirable if cleavage of a peptide is to be achieved. BDD showed improved cleavage yield and reduced adsorption for a set of small peptides, some of which had been previously shown to undergo electrochemical cleavage C-terminal to tyrosine (Tyr) and tryptophan (Trp) on porous carbon electrodes. Repeated oxidation with BDD electrodes resulted in progressively lower conversion yields due to a change in surface termination. Cathodic pretreatment of BDD at a negative potential in an acidic environment successfully regenerated the electrode surface and allowed for repeatable reactions over extended periods of time. BDD electrodes are a promising alternative to GC electrodes in terms of reduced adsorption and fouling and the possibility to regenerate them for consistent high-yield electrochemical cleavage of peptides. The fact that OH-radicals can be produced by anodic oxidation of water at elevated positive potentials is an additional advantage as they allow another set of oxidative reactions in analogy to the Fenton reaction, thus widening the scope of electrochemistry in protein and peptide chemistry and analytics. PMID:23763302

Roeser, Julien; Alting, Niels F A; Permentier, Hjalmar P; Bruins, Andries P; Bischoff, Rainer

2013-06-25

244

A disposable immunosensor for Enterobacter sakazakii based on an electrochemically reduced graphene oxide-modified electrode.  

PubMed

A disposable immunosensor based on electrochemically reduced graphene oxide (ERGO) was developed for the detection of Enterobacter sakazakii. First, the graphene was deposited on a screen-printed carbon electrode (SPCE) by an electrochemical method. Second, the horseradish peroxidase-labeled bacteria-specific antibody was assembled onto the modified electrode to enhance the sensitivity of the immunosensor. The immunosensor constructed in this study can sensitively and rapidly detect E. sakazakii, and this method may contribute to further foodborne pathogen detection. In addition, this ERGO-modified SPCE could also provide new insights into the development of immunosensors for other bacteria to facilitate rapid detection. PMID:23219558

Hu, Xue; Dou, Wenchao; Fu, Linglin; Zhao, Guangying

2012-12-03

245

Electrochemical oxidation of purine and pyrimidine bases based on the boron-doped nanotubes modified electrode.  

PubMed

Based on the excellent physicochemical properties of boron-doped carbon nanotubes (BCNTs), the electrochemical analysis of four free DNA bases at the BCNTs modified glassy carbon (GC) electrode was investigated. Herein, the BCNTs/GC electrode exhibited remarkable electrocatalytic activity towards the oxidation of purine bases (guanine (G), adenine (A)). More significantly, the direct oxidation of pyrimidine bases (thymine (T), cytosine (C)) was realized. It may be due to that BCNTs have the advantages of high electron transfer kinetics, large surface area, prominent antifouling ability and electrode activity. On basis of this, a novel and simple strategy for the determination of G, A, T and C was proposed. The BCNTs/GC electrode showed high sensitivity, wide linear range and capability of detection for the electrochemical determination of G, A, T, and C. On the other hand, the electrochemical oxidation of quaternary mixture of G, A, T, and C at the BCNTs/GC electrode was investigated. It was obtained that the peak separation between G and A, A and T, T and C were large enough for their potential recognition in mixture without any separation or pretreatment. The BCNTs/GC electrode also displayed good stability, reproducibility and excellent anti-interferent ability. Therefore, it can be believed that the BCNTs/GC electrode would provide a potential application for the electrochemical detection of DNA in the field of genetic-disease diagnosis. PMID:22154402

Deng, Chunyan; Xia, Yalin; Xiao, Chunhui; Nie, Zhou; Yang, Minghui; Si, Shihui

2011-11-20

246

Ammonium nitrogen removal from wastewater with a three-dimensional electrochemical oxidation system.  

PubMed

Ammonium-containing wastewater could cause the promotion of eutrophication and a hindrance to the disinfection of water supplies. In this study, the feasibility of removing low-concentration ammonium nitrogen from synthetic and real wastewater by electrochemical oxidation was investigated. Using laboratory-scale electrochemical systems, the effects of chloride concentration, current density, anode materials, cathode materials, electrode gap, initial ammonium concentration and three-dimensional particles on the removal of ammonium nitrogen and current efficiency (CE) were evaluated. Ammonium nitrogen removal was mainly dependent upon anode materials and current density. The performance of two- and three-dimensional electrochemical oxidation systems was comparatively discussed. Both particle electrodes could enhance ammonium nitrogen removal and increase CE. However, the mechanism of the process seemed to be different. Moreover, the interaction of zeolites adsorption and electrochemical oxidation on the anode in a three-dimensional system could favor the regeneration of zeolites. Surface morphology of the used Ru-Ir-Sn/Ti anode revealed its longer working life of electrocatalysis. The result of ammonium degradation for a real wastewater treatment plant effluent showed the degradation rates in a three-dimensional system increased by 1.4 times those in a two-dimensional system. PMID:23925182

Ding, Jing; Zhao, Qing-Liang; Wei, Liang-Liang; Chen, Yang; Shu, Xin

2013-01-01

247

Measuring fundamental properties in operating solid oxide electrochemical cells by using in situ X-ray photoelectron spectroscopy  

Microsoft Academic Search

Photoelectron spectroscopic measurements have the potential to provide detailed mechanistic insight by resolving chemical states, electrochemically active regions and local potentials or potential losses in operating solid oxide electrochemical cells (SOCs), such as fuel cells. However, high-vacuum requirements have limited X-ray photoelectron spectroscopy (XPS) analysis of electrochemical cells to ex situ investigations. Using a combination of ambient-pressure XPS and CeO2-x\\/YSZ\\/Pt

Chunjuan Zhang; Michael E. Grass; Anthony H. McDaniel; Steven C. Decaluwe; Farid El Gabaly; Zhi Liu; Kevin F. McCarty; Roger L. Farrow; Mark A. Linne; Zahid Hussain; Gregory S. Jackson; Hendrik Bluhm; Bryan W. Eichhorn

2010-01-01

248

Microcystin-LR and chemically degraded microcystin-LR electrochemical oxidation.  

PubMed

Microcystins (MCs) are cyclic hepatotoxic heptapeptides produced by certain strains of freshwater cyanobacteria toxic for humans and animals. The electrochemical behaviour of microcystin-LR (MC-LR) at a glassy carbon electrode (GCE) was investigated using cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). The oxidation of MC-LR is a diffusion-controlled irreversible and pH-independent process that occurs with the transfer of only one electron and does not involve the formation of any electroactive oxidation product. Upon incubation in different pH electrolytes, homogeneous degradation of MC-LR in solution was electrochemically detected by the appearance of a new oxidation peak at a lower potential. The electrochemical behaviour of chemically degraded MC-LR is an irreversible, pH-dependent process, and involves the formation of two redox products that undergo reversible oxidation. The formation of degradation products of MC-LR was confirmed by HPLC with UV detection at room temperature. Experiments were also carried out in solutions containing constituent MC-LR amino acids, which enabled the understanding of the MC-LR electron transfer reaction and degradation. An oxidation mechanism for MC-LR is proposed. PMID:22377975

Lopes, Ilanna C; Santos, Paulina V F; Diculescu, Victor C; Peixoto, Francisco M P; Araújo, Mário C U; Tanaka, Auro A; Oliveira-Brett, Ana Maria

2012-03-01

249

Advanced oxidation technologies for chemical demilitarization  

SciTech Connect

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory. The main project objective was to establish a technical basis for future program development in the area of chemical warfare agent destruction using a Los Alamos-developed advanced oxidation process: a two-stage device consisting of thermal packed-bed reactor (PBR) and a nonthermal plasma (NTP) reactor. Various compounds were evaluated as potential surrogates for chemical warfare (CW) agents. Representative effluent mass balances were projected for future comparisons with incinerators. The design and construction of lab-scale PBR/NTP reactors (consisting of a liquid injection and metering system, electric furnace, condensers, chemical traps, plasma reactors, power supplies, and chemical diagnostics) has been completed. This equipment, the experience gained from chemical-processing experiments, process modeling, and an initial demonstration of the feasibility of closed-loop operation, have provided a technical basis for further demonstrations and program development efforts.

Rosocha, L.A.; Korzekwa, R.A.; Monagle, M.; Coogan, J.J.; Tennant, R.A.; Brown, L.F.; Currier, R.P.

1996-12-31

250

Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides.  

PubMed

Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K(3)[Fe(CN)(6)] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO(3) form. PMID:20886983

Salerno, Marco

2010-09-01

251

Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides  

NASA Astrophysics Data System (ADS)

Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K3[Fe(CN)6] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO3 form.

Salerno, Marco

2010-09-01

252

Mechanism of glucose electrochemical oxidation on gold surface  

Microsoft Academic Search

The complex oxidation of glucose at the surface of gold electrodes was studied in detail in different conditions of pH, buffer and halide concentration. As observed in previous studies, an oxidative current peak occurs during the cathodic sweep showing a highly linear dependence on glucose concentration, when other electrolyte conditions are unchanged. The effect of the different conditions on the

Mauro Pasta; Fabio La Mantia; Yi Cui

2010-01-01

253

Electrochemical preparation of cuprous oxid powder: Part II. Process conditions  

Microsoft Academic Search

Practical electrosynthesis of cuprous oxide powder was carried out on a laboratory scale in a cell specially constructed both with and without a diaphragm under the various operating conditions guided by the authors' previous research. The electrolysis was appraised in terms of the quality of the cuprous oxide product, the electrodissolution of the copper anode, and the SEM microstructure of

J. Ji

1990-01-01

254

Catalytic activity of NiMnO3 for visible light-driven and electrochemical water oxidation.  

PubMed

NiMnO3 was found to be an efficient catalyst for light-driven water oxidation using [Ru(bpy)3](2+) and S2O8(2-) as a photosensitiser and a sacrificial oxidant, respectively. NiMnO3 exhibited remarkably high catalytic activity in comparison with manganese oxides and nickel oxide. For electrochemical water oxidation, the highest catalytic current was also obtained with NiMnO3 among the manganese oxides. PMID:24113542

Hong, Dachao; Yamada, Yusuke; Nomura, Akifumi; Fukuzumi, Shunichi

2013-10-23

255

Enhancing electrochemical detection on graphene oxide-CNT nanostructured electrodes using magneto-nanobioprobes  

PubMed Central

Graphene and related materials have come to the forefront of research in electrochemical sensors during recent years due to the promising properties of these nanomaterials. Further applications of these nanomaterials have been hampered by insufficient sensitivity offered by these nanohybrids for the type of molecules requiring lower detection ranges. Here, we report a signal amplification strategy based on magneto-electrochemical immunoassay which combines the advantages of carbon nanotube and reduced graphene oxide together with electrochemical bursting of magnetic nanoparticles into a large number of metal ions. Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration. We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples. The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples.

Sharma, Priyanka; Bhalla, Vijayender; Dravid, Vinayak; Shekhawat, Gajendera; Jinsong-Wu, J W; Prasad, E. Senthil; Suri, C. Raman

2012-01-01

256

Boosting supercapacitor performance of carbon fibres using electrochemically reduced graphene oxide additives.  

PubMed

Modifying conventional materials with new recipes represents a straightforward yet efficient way to realize large-scale applications of new materials. Electrochemically reduced graphene oxide (ERGO) coated carbon fibres (CFs), prepared as fibre-like supercapacitor electrodes, exhibited excellent electrochemical energy storage performance. Upon addition of only a small amount (?1 wt%) of ERGO, the hybrid fibres showed superior electrochemical capacitances (nearly three orders of magnitude enhanced) compared to pure CFs in both aqueous and gel electrolytes. Meanwhile, the energy density did not decrease notably as the power density increased. The superior capacitive performance could be attributed to the synergistic effect between wrinkled and porous ERGO sheets and highly conductive CFs. This fibre electrode material also offered advantages such as easy operation, mass production capability, mechanical flexibility and robustness, and could have an impact on a wide variety of potential applications in energy and electronic fields. PMID:24141749

Cao, Yachang; Zhu, Miao; Li, Peixu; Zhang, Rujing; Li, Xinming; Gong, Qianming; Wang, Kunling; Zhong, Minlin; Wu, Dehai; Lin, Feng; Zhu, Hongwei

2013-10-21

257

Performance Evaluation of SOFC System usingElectrochemical Direct Oxidation of Methane  

NASA Astrophysics Data System (ADS)

We evaluated the performance of systems composed of a solid oxide fuel cell (SOFC) using electrochemical direct oxidation of methane and a conventional steam-reforming-type SOFC (SRSOFC). Net thermal efficiency in an atmospheric partial-oxidation-type SOFC (POSOFC)-SRSOFC system was 8% higher than that in a simple SRSOFC system in the output range of more than 35 kW. The efficiency in a pressurized POSOFC-SRSOFC-gas-turbine (GT) system was slightly higher than that in a pressurized SRSOFC-GT system.

Yokoo, Masayuki; Take, Tetsuo; Ohtsu, Satoshi

258

Electrochemical Deposition of Iron Nanoneedles on Titanium Oxide Nanotubes  

SciTech Connect

Iron as a catalyst has wide applications for hydrogen generation from ammonia, photodecomposition of organics, and carbon nanotube growth. Tuning the size and shape of iron is meaningful for improving the catalysis efficiency. It is the objective of this work to prepare nanostructured iron with high surface area via electrochemical deposition. Iron nanoneedles were successfully electrodeposited on Ti supported TiO2 nanotube arrays in a chlorine-based electrolyte containing 0.15 M FeCl2 {center_dot} 4H2O and 2.0 M HCl. Transmission electron microscopic analysis reveals that the average length of the nanoneedles is about 200 nm and the thickness is about 10 nm. It has been found that a high overpotential at the cathode made of Ti/TiO2 nanotube arrays is necessary for the formation of the nanoneedles. Cyclic voltammetry test indicates that the electrodeposition of iron nanoneedles is a concentration-limited process.

Gan Y. X.; Zhang L.; Gan B.J.

2011-10-01

259

[Degradation of aniline by a dual-electrode electrochemical oxidation process].  

PubMed

The efficiency and the mechanism of aniline degradation by an electrochemical oxidation process using a Ti/SnO2-Sb2O5 electrode as the anode and a graphite electrode as the cathode, were studied in two aqueous electrolytes with/without Fe2+. The results showed that the reasonable anodic potential was about 2.0 V +/- 0.1 V for Ti/SnO2-Sb2O5 electrode to oxidize organic compounds, while the optimum cathodic potential was -0.65 V for graphite electrode to reduce O2 generating H2O2. The oxidation degradation of aniline could not take place only by the single action of H2O2. Anodic oxidation was accounted for the degradation of aniline in the absence of Fe2+, while in the presence of Fe2+ both electro-Fenton oxidation and anodic oxidation (dual-electrode electrochemical oxidation) could degradate aniline effectively, and in this case the former was the main mechanism. Under the conditions of -0.65 V cathodic potential, pH 3.0 and 0.5 mmol x L(-1) Fe2+, the removal rate of COD was 77.5% after 10 h treatment and a current efficiency of 97.8% for COD removal could be obtained. This work indicates that the dual-electrode electrochemical oxidation is feasible for the degradation of organic compounds with a high current efficiency by using Ti/SnO2-Sb2O5 as anode as well as the reasonable anodic and cathodic potentials. PMID:22619954

Cen, Shi-Hong; Song, Xiao-Yan; Chu, Yan-Yang

2011-08-01

260

Electroless deposition of conformal nanoscale iron oxide on carbon nanoarchitectures for electrochemical charge storage.  

PubMed

We describe a simple self-limiting electroless deposition process whereby conformal, nanoscale iron oxide (FeO(x)) coatings are generated at the interior and exterior surfaces of macroscopically thick ( approximately 90 microm) carbon nanofoam paper substrates via redox reaction with aqueous K(2)FeO(4). The resulting FeO(x)-carbon nanofoams are characterized as device-ready electrode structures for aqueous electrochemical capacitors and they demonstrate a 3-to-7 fold increase in charge-storage capacity relative to the native carbon nanofoam when cycled in a mild aqueous electrolyte (2.5 M Li(2)SO(4)), yielding mass-, volume-, and footprint-normalized capacitances of 84 F g(-1), 121 F cm(-3), and 0.85 F cm(-2), respectively, even at modest FeO(x) loadings (27 wt %). The additional charge-storage capacity arises from faradaic pseudocapacitance of the FeO(x) coating, delivering specific capacitance >300 F g(-1) normalized to the content of FeO(x) as FeOOH, as verified by electrochemical measurements and in situ X-ray absorption spectroscopy. The additional capacitance is electrochemically addressable within tens of seconds, a time scale of relevance for high-rate electrochemical charge storage. We also demonstrate that the addition of borate to buffer the Li(2)SO(4) electrolyte effectively suppresses the electrochemical dissolution of the FeO(x) coating, resulting in <20% capacitance fade over 1000 consecutive cycles. PMID:20731433

Sassin, Megan B; Mansour, Azzam N; Pettigrew, Katherine A; Rolison, Debra R; Long, Jeffrey W

2010-08-24

261

Electrochemical behavior of reactively sputtered iron-doped nickel oxide  

Microsoft Academic Search

Iron-doped nickel oxide films were deposited by reactive sputtering from elemental and alloy targets in a 20% oxygen\\/argon atmosphere and were characterized for use as oxygen evolution catalysts. The incorporation of iron reduced the overpotential required for oxygen evolution by as much as 300 mV at a current density of 100 mA\\/cm² compared to undoped nickel oxide deposited under similar

Eric L. Miller; R. E. Rocheleau

1997-01-01

262

Treatment of methyl orange dye wastewater by cooperative electrochemical oxidation in anodic-cathodic compartment.  

PubMed

Electrochemical oxidation of methyl orange wastewater was studied using Ti/IrO(2)/RuO(2) anode and a self-made Pd/C O(2)-fed cathode in the divided cell with a terylene diaphragm. The result indicated that the appropriate rate of feeding air improved the methyl orange removal efficiency. The discoloration efficiency of methyl orange in the divided cell increased with increasing current density. The initial pH value had some effect on the discoloration of methyl orange, which became not obvious when the pH ranged from 2 to 10. However, the average removal efficiency of methyl orange wastewater in terms of total organic carbon (TOC) can reach 89.3%. The methyl orange structure had changed in the electrolytic process, and the characteristic absorption peak of methyl orange was about 470 nm. With the extension of electrolysis time, the concentration of methyl orange gradually reduced; wastewater discoloration rate increased gradually. The degradation of methyl orange was assumed to be cooperative oxidation by direct or indirect electrochemical oxidation at the anode and H(2)O(2), ·OH, O(2)(-)· produced by oxygen reduction at the cathode in the divided cell. Therefore, the cooperative electrochemical oxidation of methyl orange wastewater in the anodic-cathodic compartment had better degradation effects. PMID:23202555

Pang, L; Wang, H; Bian, Z Y

2013-01-01

263

Microfluidic Electrochemical Sensor for On-line Monitoring of Aerosol Oxidative Activity  

PubMed Central

Particulate matter (PM) air pollution has a significant impact on human morbidity and mortality; however, the mechanisms of PM-induced toxicity are poorly defined. A leading hypothesis states that airborne PM induces harm by generating reactive oxygen species (ROS) in and around human tissues, leading to oxidative stress. We report here, a system employing a microfluidic electrochemical sensor coupled directly to a Particle-into-Liquid-Sampler (PILS) system to measure aerosol oxidative activity in an on-line format. The oxidative activity measurement is based on the dithiothreitol assay (DTT assay) where after oxidized by PM, the remaining reduced DTT was analyzed by the microfluidic sensor. The sensor consists of an array of working, reference, and auxiliary electrodes fabricated in a poly(dimethylsiloxane) (PDMS)-based microfluidic device. Cobalt (II) phthalocyanine (CoPC)-modified carbon paste was used as the working electrode material allowing selective detection of reduced DTT. The electrochemical sensor was validated off-line against the traditional DTT assay using filter samples taken from urban environments and biomass burning events. After off-line characterization, the sensor was coupled to a PILS to enable on-line sampling/analysis of aerosol oxidative activity. Urban dust and industrial incinerator ash samples were aerosolized in an aerosol chamber and analyzed for their oxidative activity. The on-line sensor reported DTT consumption rates (oxidative activity) in good correlation with aerosol concentration (R2 from 0.86–.97) with a time-resolution of approximately 3 minutes.

Sameenoi, Yupaporn; Koehler, Kirsten; Shapiro, Jeff; Boonsong, Kanokporn; Sun, Yele; Collett, Jeffrey; Volckens, John; Henry, Charles S.

2012-01-01

264

Peptide methionine sulfoxide reductase A (MsrA): direct electrochemical oxidation on carbon electrodes.  

PubMed

The direct electrochemical behaviour of peptide methionine sulfoxide reductase A (MsrA) adsorbed on glassy carbon and boron doped diamond electrodes surface, was studied over a wide pH range by cyclic and differential pulse voltammetry. MsrA oxidation mechanism occurs in three consecutive, pH dependent steps, corresponding to the oxidation of tyrosine, tryptophan and histidine amino acid residues. At the glassy carbon electrode, the first step corresponds to the oxidation of tyrosine and tryptophan residues and occurs for the same potential. The advantage of boron doped diamond electrode was to enable the separation of tyrosine and tryptophan oxidation peaks. On the second step occurs the histidine oxidation, and on the third, at higher potentials, the second tryptophan oxidation. MsrA adsorbs on the hydrophobic carbon electrode surface preferentially through the three hydrophobic domains, C1, C2 and C3, which contain the tyrosine, tryptophan and histidine residues, and tryptophan exists only in these regions, and undergo electrochemical oxidation. PMID:22967951

Enache, T A; Oliveira-Brett, A M

2012-08-21

265

Electrolytic destruction of spent tributylphosphate extractant using silver catalyzed electrochemical oxidation  

SciTech Connect

Silver catalyzed electrochemical oxidation of organic species is examined in analytical detail. This paper describes the mechanisms, reactions rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantity laboratory waste is described. The 200 mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and non-radioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II) which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene {sup 1,2}. This paper focuses on the destruction of tributylphosphate (TBP) although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids. The process has the potential for RCRA (Resource Conservation and Recovery Act) waste treatment as well as disposal of large amounts of radioactive organic waste.

Almon, A.C.; Buchanan, B.R.

1990-01-01

266

Synthesis and Microstructural Characterization of Manganese Oxide Electrodes for Application as Electrochemical Supercapacitors  

NASA Astrophysics Data System (ADS)

The aim of this thesis work was to synthesize Mn-based oxide electrodes with high surface area structures by anodic electrodeposition for application as electrochemical capacitors. Rod-like structures provide large surface areas leading to high specific capacitances. Since templated electrosynthesis of rods is not easy to use in practical applications, it is more desirable to form rod-like structures without using any templates. In this work, Mn oxide electrodes with rod-like structures (˜1.5 µm in diameter) were synthesized from a solution of 0.01 M Mn acetate under galvanostatic control without any templates, on Au coated Si substrates. The electrochemical properties of the synthesized nanocrystalline electrodes were investigated to determine the effect of morphology, chemistry and crystal structure on the corresponding electrochemical behavior of Mn oxide electrodes. Mn oxides prepared at different current densities showed a defective antifluoritetype crystal structure. The rod-like Mn oxide electrodes synthesized at low current densities (5 mAcm.2) exhibited a high specific capacitance due to their large surface areas. Also, specific capacity retention after 250 cycles in an aqueous solution of 0.5 M Na2SO4 at 100 mVs -1 was about 78% of the initial capacity (203 Fg-1 ). To improve the electrochemical capacitive behavior of Mn oxide electrodes, a sequential approach and a one-step method were adopted to synthesize Mn oxide/PEDOT electrodes through anodic deposition on Au coated Si substrates from aqueous solutions. In the former case, free standing Mn oxide rods (about 10 µm long and less than 1.5 µm in diameter) were first synthesized, then coated by electro-polymerization of a conducting polymer (PEDOT) giving coaxial rods. The one-step, co-electrodeposition method produced agglomerated Mn oxide/PEDOT particles. The electrochemical behavior of the deposits depended on the morphology and crystal structure of the fabricated electrodes, which were affected by the composition and pH of the electrolyte, temperature, current density and polymer deposition time. Mn oxide/PEDOT coaxial core/shell rods consisted of MnO2 with an antifluorite-type structure coated with amorphous PEDOT. The Mn oxide/PEDOT coaxial core/shell electrodes prepared by the sequential method showed significantly better specific capacity and redox performance properties relative to both uncoated Mn oxide rods and co- electrodeposited Mn oxide/PEDOT electrodes. The best specific capacitance for Mn oxide/PEDOT rods produced sequentially was ˜295 F g-1 with ˜92% retention after 250 cycles in 0.5 M Na2SO4 at 100 mV s-1. To further improve the electrochemical capacitive behavior of Mn oxide electrodes, Co-doped and Fe-doped Mn oxide electrodes with a rod-like morphology and antifluorite-type crystal structure were synthesized by anodic electrodeposition, on Au coated Si substrates, from dilute solutions of Mn acetate and Co sulphate and Mn acetate and Fe chloride. Also, Mn-Co oxide/PEDOT coaxial core/shell rods were synthesized by applying a shell of PEDOT on Mn-Co oxide electrodes. Mn-Co oxide/PEDOT electrodes consisted of MnO2, with partial Co 2+ and Co3+ ion substitution for Mn4+, and amorphous PEDOT. Mn-Fe oxide electrodes consisted of MnO2, with partial Fe2+ and Fe3+ ion substitution for Mn4+. Electrochemical analysis showed that the capacitance values for all deposits increased with increasing scan rate to 100 mVs -1, and then decreased after 100 mVs-1. The Mn-Co oxide/PEDOT electrodes showed improved specific capacity and electrochemical cyclability relative to uncoated Mn-Co oxides and Mn-Fe oxides. Mn-Co oxide/PEDOT electrodes with rod-like structures had high capacitances (up to 310 Fg -1) at a scan rate of 100 mVs-1 and maintained their capacitance after 500 cycles in 0.5 M Na2SO4 (91% retention). Capacitance reduction for the deposits was mainly due to the loss of Mn ions by dissolution in the electrolyte solution. To better understand the nucleation and growth mechanisms of Mn oxide electrodes, the effects of supersaturation ratio on the

Babakhani, Banafsheh

267

Selective Separation of Cs and Sr from LiCl-Based Salt for Electrochemical Processing of Oxide Spent Nuclear Fuel  

Microsoft Academic Search

Electrochemical processing technology is currently being used for the treatment of metallic spent fuel from the Experimental Breeder Reactor-II at Idaho National Laboratory. The treatment of oxide-based spent nuclear fuel via electrochemical processing is possible provided there is a front-end oxide reduction step. During this reduction process, certain fission products, including Cs and Sr, partition into the salt phase and

P. Sachdev; M. F. Simpson; S. M. Frank; K. Yano; V. Utgikar

2008-01-01

268

Applicability of electrochemical methods to carwash wastewaters for reuse. Part 2: Electrocoagulation and anodic oxidation integrated process  

Microsoft Academic Search

In this work a combined two-step process consisting in the electrochemical coagulation with iron anodes and the electrochemical oxidation with boron-doped diamond anode (BDD) was developed for the treatment of a real carwash wastewater. The effects of important operating parameters such as current density, electrolysis time and pH on the surfactants oxidation, COD removal and energy consumptions during electrocoagulation have

Marco Panizza; Giacomo Cerisola

2010-01-01

269

Nano-Ag-Nafion modified Pt electrode for oxidation of volatile organic compounds: an electrochemical study.  

PubMed

In this work, we describe Nano-Ag-Nafion coated pt electrode for oxidation of volatile organic compound (VOC), here acetaldehyde. Electrochemically synthesized Nano-Ag-Nafion film on Pt was analyzed by electrochemically in various electrolyte solutions like nitric acid, sulfuric acid, potassium nitrate, and potassium hydroxide for its stability. High stability of Nano-Ag-Nafion film appeared in potassium hydroxide medium among electrolyte solutions studied. Electrocatalysis of acetaldehyde was occurred only in acid and neutral medium. A catalytic oxidative peak during cathodic voltammetric reduction scan was observed at 1.75 V, which, unusual redox behavior, follows EC' reaction path way between electrogenerated Ag(II) and acetaldehyde. For Nano-Ag potential applicability, a calibration plot was drawn from various concentration range of acetaldehyde to check the maximum concentration level of acetaldehyde degradation in air. PMID:22103205

Muthuraman, G; Chung, Sang Joon; Moon, Il Shik

2011-08-01

270

Electrochemical oxidation and reduction of chemisorbed ligninsulfonic acid species and aromatic compounds simulating lignin  

SciTech Connect

The electrochemical oxidation and reduction of chemisorbed ligninsulfonic acid species and of aromatic compounds simulating lignin (4-hydroxy-3-methoxybenzylsulfonic acid, vanillic alcohol) were examined at the platinum electrode. It was shown that the slow step of the oxidation and reduction processes is the reaction of the chemisorbed organic species with H/sub ads/ and OH/sub ads/ species generated electrochemically from the solvent. The drop in steady-state coverage which is found to occur with all the materials studied at E/sub r/ < 0.2 V is due to hydrogenation of the chemisorbed species, but the drop which is found to occur at E/sub r/ > 0.2 v is not due to any electrooxidation process, since electrooxidation of the chemisorbed species only starts to occur with noticeable rates at E/sub r/ > 0.7 V.

Shchukin, I.V.; Vasil'ev, Yu.B.; Kazarinov, V.E.; Babkin, V.A.

1987-09-01

271

A molecularly imprinted polymer with incorporated graphene oxide for electrochemical determination of quercetin.  

PubMed

The molecularly imprinted polymer based on polypyrrole film with incorporated graphene oxide was fabricated and used for electrochemical determination of quercetin. The electrochemical behavior of quercetin on the modified electrode was studied in detail using differential pulse voltammetry. The oxidation peak current of quercetin in B-R buffer solution (pH = 3.5) at the modified electrode was regressed with the concentration in the range from 6.0 × 10(-7) to 1.5 × 10(-5) mol/L (r2 = 0.997) with a detection limit of 4.8 × 10(-8) mol/L (S/N = 3). This electrode showed good stability and reproducibility. In the above mentioned range, rutin or morin which has similar structures and at the same concentration as quercetin did not interfere with the determination of quercetin. The applicability of the method for complex matrix analysis was also evaluated. PMID:23698263

Sun, Si; Zhang, Mengqi; Li, Yijun; He, Xiwen

2013-04-25

272

Electrochemical impedance spectroscopy studies of lithium diffusion in doped manganese oxide  

SciTech Connect

Cathode performance is critical to lithium ion rechargeable battery performance; effects of doping lithium manganese oxide cathode materials on cathode performance are being investigated. In this paper, Li diffusion in Al-doped LiMn{sub 2}O{sub 4} was studied and found to be controlled by the quantity of Al dopant. Electrochemical cycling was conducted at 0.5mA/cm{sub 2}; electrochemical impedance spectra were taken at open circuit potential, with impedance being measured at 65 kHz-0.01 Hz. As the Al dopant level was increased, the Li diffusion rate decreased; this was attributed to the decreased lattice parameter of the doped oxide.

Johnson, B.J.; Doughty, D.H.; Voigt, J.A.; Boyle, T.J.

1996-06-01

273

A Molecularly Imprinted Polymer with Incorporated Graphene Oxide for Electrochemical Determination of Quercetin  

PubMed Central

The molecularly imprinted polymer based on polypyrrole film with incorporated graphene oxide was fabricated and used for electrochemical determination of quercetin. The electrochemical behavior of quercetin on the modified electrode was studied in detail using differential pulse voltammetry. The oxidation peak current of quercetin in B-R buffer solution (pH = 3.5) at the modified electrode was regressed with the concentration in the range from 6.0 × 10?7 to 1.5 × 10?5 mol/L (r2 = 0.997) with a detection limit of 4.8 × 10?8 mol/L (S/N = 3). This electrode showed good stability and reproducibility. In the above mentioned range, rutin or morin which has similar structures and at the same concentration as quercetin did not interfere with the determination of quercetin. The applicability of the method for complex matrix analysis was also evaluated.

Sun, Si; Zhang, Mengqi; Li, Yijun; He, Xiwen

2013-01-01

274

Platinum catalyst on ordered mesoporous carbon with controlled morphology for methanol electrochemical oxidation  

NASA Astrophysics Data System (ADS)

Ordered mesoporous carbons CMK-3 with various morphologies are synthesized by using various mesoporous silica SBA-15 as template and then support to prepare Pt/CMK-3 catalyst. The obtained catalysts are compared in terms of the electrocatalytic activity for methanol oxidation in sulfuric acidic solutions. The structure characterizations and electrochemical analysis reveal that Pt catalysts with the CMK-3 support of large particle size and long channel lengths possess larger electrochemical active surface area (ECSA) and higher activity toward methanol oxidation than those with the other two supports. The better performance of Pt/CMK-3 catalyst may be due to the larger area of electrode/electrolyte interface and larger ECSA value of Pt catalyst, which will provide better structure in favor of the mass transport and the electron transport.

Kong, Ling-Bin; Li, Heng; Zhang, Jing; Luo, Yong-Chun; Kang, Long

2010-09-01

275

Biological applications of the electrochemical sensing of nitric oxide: fundamentals and recent developments.  

PubMed

Nitric oxide (NO) is a unique cellular messenger linked to a number of important biological processes. Its free radical nature, small size and fast diffusivity make it highly reactive and membrane permeable. Unfortunately, its reactivity, coupled with the inherent complexity of in situ biological measurements, makes it a challenge to detect. For the past 20 years, electrochemical methods have been used to investigate the role of NO in a number of biological processes, including vascular physiology, immune response, neuronal mediation, tissue growth and oxidative stress. This review examines the biological applications of electrochemical NO sensors and the technologies used to elucidate different physiological phenomena associated with this unique biomolecule with a specific focus on the developments and innovations reported in the last 3 years. PMID:23096755

Trouillon, Raphaël

2013-01-01

276

Electrochemical properties of iodine-containing lithium manganese oxide spinel  

Microsoft Academic Search

Iodine-containing, cation-deficient, lithium manganese oxides (ICCD-LMO) are prepared by reaction of MnO2 with LiI. The MnO2 is completely transformed into spinel-structured compounds with a nominal composition of Li1??Mn2?2?O4Ix. A sample prepared at 800°C, viz. Li0.99Mn1.98O4I0.02, exhibits an initial discharge capacity of 113mAhg?1 with good cycleability and rate capability in the 4-V region. Iodine-containing, lithium-rich lithium manganese oxides (ICLR-LMO) are also

Chi-Hwan Han; Young-Sik Hong; Hyun-Sil Hong; Keon Kim

2002-01-01

277

Chemical and electrochemical oxidation of small organic molecules  

NASA Astrophysics Data System (ADS)

Direct oxidation fuel cells using proton-exchange membrane electrolytes have long been recognized as being an attractive mode of power generation. The current work addresses the electro-oxidation characteristics of a number of potential fuels on Pt-based electrodes which can be used in direct oxidation fuel cells, including hydrocarbons and oxygenated molecules, such as alcohols, formates, ethers, and acetals. Promising alternative fuels which were identified, such as trimethoxymethane and dimethoxymethane, were then investigated in liquid-feed PEM-based fuel cells. In addition to investigating the nature of the anodic electro-oxidation of organic fuels, effort was also devoted to developing novel polymer electrolyte membranes which have low permeability to organic molecules, such as methanol. This research was initiated with the expectation of reducing the extent of fuel crossover from the anode to the cathode in the liquid-feed design fuel cell which results in lower fuel efficiency and performance. Other work involving efforts to improve the performance of direct oxidation fuel cell includes research focused upon improving the kinetics of oxygen reduction. There is continued interest in the identification of new, safe, non-toxic, and inexpensive reagents which can be used in the oxidation of organic compounds. Urea-hydrogen peroxide (UHP), a hydrogen bonded adduct, has been shown to serve as a valuable source of hydrogen peroxide in a range of reactions. UHP has been shown to be ideal for the monohydroxylation of aromatics, including toluene, ethylbenzene, p-xylene, m-xylene, and mesitylene, as well as benzene, in the presence of trifluoromethanesulfonic acid. It was also found that aniline was converted to a mixture containing primarily azobenzene, azoxybenzene and nitrobenzene when reacted with UHP in glacial acetic acid. A number of aniline derivatives have been investigated and it was observed that the corresponding azoxybenzene derivatives could be generated as the major products in good to excellent yields. The oxidation of other organic substrates was also investigated using urea-hydrogen peroxide as an oxidation reagent, including cyclohexylamine, 1-adamantaneamine, and adamantane.

Smart, Marshall C.

278

Effects of natural and electrochemical oxidation processes on acoustic waves in porous silicon films  

NASA Astrophysics Data System (ADS)

Brillouin scattering has been performed to study the effects of natural and electrochemical oxidation on the surface and bulk acoustic mode properties of porous silicon films. The acoustic mode frequencies are observed to decrease with increasing oxidation time and this is attributed to the progressive transformation of silicon-silicon bonds on the inner pore walls into SiO2. The dependence of the surface and bulk acoustic mode frequencies on the natural oxidation time allows the evaluation of these wave frequencies for a porous-SiO2 glass film, and hence the estimation of its bulk modulus. Both Brillouin and Raman data confirm the expectation that oxidation leads to a reduction in silicon nanoparticle size, and provide a correlation between the redsifted acoustic mode frequency and the oxidation period.

Fan, H. J.; Kuok, M. H.; Ng, S. C.; Lim, H. S.; Liu, N. N.; Boukherroub, R.; Lockwood, D. J.

2003-07-01

279

New Advanced Oxidation Technologies for Destruction of Pollutants in Water.  

National Technical Information Service (NTIS)

The use of the set of advanced oxidation technologies (plasma, bio- and photochemical) for the purification and disinfection of the heavy contaminated water is proposed. The plasma and photochemical techniques are used for the destruction of complicated o...

A. Kravchenko A. Trokhymchuk V. Chernyak Y. Tarasova

2001-01-01

280

ADVANCED OXIDATION PROCESSES (AOP'S FOR THE TREATMENT OF CCL CHEMICALS  

EPA Science Inventory

Research on treatment of Contaminant Candidate List (CCL) chemicals is being conducted. Specific groups of contaminants on the CCL will be evaluated using numerous advanced oxidation processes (AOPs). Initially, these CCL contaminants will be evaluated in groups based on chemical...

281

Advanced oxidation processes coupled with electrocoagulation for the exhaustive abatement of Cr-EDTA  

Microsoft Academic Search

Using Cr-EDTA as a model system, a two-step method has been investigated for the abatement of persistent chromium complexes in water. The treatment consists of an oxidative decomposition of the organic ligands by means of ozonization or electrochemical oxidation at a boron doped diamond (BDD) electrode, followed by removal of the metal via electrochemical coagulation. In the designed synthetic waste,

Christian Durante; Marco Cuscov; Abdirisak Ahmed Isse; Giancarlo Sandonà; Armando Gennaro

2011-01-01

282

Electrochemical synthesis and sintering of nanocrystalline cerium(IV) oxide powders  

Microsoft Academic Search

Nanocrystalline CeOâ powders were prepared electrochemically by the cathodic electrogeneration of base, and their sintering behavior was investigated. X-ray diffraction and transmission electron microscopy revealed that the as-prepared powders were crystalline cerium(IV) oxide with the cubic fluorite structure. The lattice parameter of the electrogenerated material was 0.5419 nm. The powders consisted of nonaggregated, faceted particles. The average crystallite size was

Z. Zhou; Richard J. Phillips; Jay A. Switzer

1995-01-01

283

Treatment of coking wastewater by coupling electrochemical oxidation and flocculation technology  

Microsoft Academic Search

The coking wastewater drainage will bring severe water environmental pollution, so reuse of post-treatment coking wastewater as make-up water for circulating cooling system is an important way. Electrochemical oxidation combined flocculation technology was proposed for treating coking wastewater. The effects of the electrolytic voltage, current density, electrode distance, pH value, electrolytic time, concentration of electrolyte and the dosage of flocculent

Lei Zhang; Gaifeng Xue; Shangchao Liu; Nan Zhang; Aimin Duan; Lina Wang; Gang Liu

2011-01-01

284

Electrochemical impedance spectroscopy of oxidized and hydrogen-terminated nitrogen-induced conductive ultrananocrystalline diamond  

Microsoft Academic Search

We have studied the electrochemical impedance spectroscopy of conductive ultrananocrystalline diamond (UNCD) modified by either oxidation or hydrogenation surface treatments. The impedance was measured in the frequency range from 0.1Hz to 40kHz at different DC voltages and the results fitted to an equivalent electrical circuit. Despite the complexity of the conductive UNCD surface, composed of sp3-bonded grains and grain boundaries

Jorge Hernando; Simon Q. Lud; Paola Bruno; Dieter M. Gruen; Martin Stutzmann; Jose A. Garrido

2009-01-01

285

Electrochemical oxidation of industrial wastewater with the tube type electrolysis module system  

Microsoft Academic Search

Electrochemical oxidation effects of the tube type electrolysis module system were investigated for the treatment of industrial wastewater. The tube type electrolysis module consisted of a rod anode and an outer tube cathode. Materials used for the anode were titanium electroplated with RuO2 and IrO2 respectively. Stainless steel was used for the cathode. Chlorate production was one of major factors

Jongsik Jeong; Jaebok Lee

286

Electrochemical immunosensors for cancer biomarker with signal amplification based on ferrocene functionalized iron oxide nanoparticles  

Microsoft Academic Search

Ultrasensitive sandwich type electrochemical immunosensors for the detection of cancer biomarker prostate specific antigen (PSA) is described which uses graphene sheet (GS) sensor platform and ferrocene functionalized iron oxide (Fe3O4) as label. To fabricate the labels, dopamine (DA) was first anchored onto Fe3O4 surface followed by conjugating ferrocene monocarboxylic acid (FC) and secondary-antibody (Ab2) onto Fe3O4 through the amino groups

He Li; Qin Wei; Jing He; Ting Li; Yanfang Zhao; Yanyan Cai; Bin Du; Zhiyong Qian; Minghui Yang

2011-01-01

287

Electrochemical oxidation of bisphenol-A from aqueous solution using graphite electrodes  

Microsoft Academic Search

Electrochemical oxidation of bisphenol-A (BPA) from aqueous solution using graphite electrodes has been investigated. The effect of the types and concentration of supporting electrolytes, initial pH and applied current density on the performance of the process were examined. During electrolysis, concentration of BPA has been monitored and determined using UV-vis spectra, chemical oxygen demand (COD) and energy consumption. NaCl has

M. Govindaraj; R. Rathinam; C. Sukumar; M. Uthayasankar; S. Pattabhi

2012-01-01

288

One step hydrothermal synthesis of a carbon nanotube/cerium oxide nanocomposite and its electrochemical properties  

NASA Astrophysics Data System (ADS)

A carbon nanotube (CNT)/cerium oxide composite was prepared by a one-pot hydrothermal reaction in the presence of KOH and capping agent polyvinylpyrrolidone. The nanocomposite displayed pronounced capacitive behaviour with very small diffusion resistance. The electrochemical performance of the composite electrode in a symmetric supercapacitor displayed a high energy density of 35.9 Wh kg-1 corresponding to a specific capacitance of 289 F g-1. These composite electrodes also demonstrated a long cycle life with better capacity retention.

Kalubarme, Ramchandra S.; Kim, Yong-Han; Park, Chan-Jin

2013-09-01

289

Electrochemical reduction of niobium from oxide-fluoride melts upon electroslag melting  

Microsoft Academic Search

Some regularities of electrochemical reduction of niobium from oxide-fluoride melts upon electroslag melting (ESM) have been\\u000a established for various electrical regimes. It has been found that the use of an asymmetric electric current during ESM substantially\\u000a improves the technological parameters of the electrolysis process. Based on the experimental data obtained, a special program\\u000a has been developed for correcting the electrical

S. A. Istomin; E. A. Pastukhov; S. A. Krasikov; V. V. Ryabov

2007-01-01

290

Fabrication and electrochemical performance of solid oxide fuel cell components by atmospheric and suspension plasma spray  

Microsoft Academic Search

The theory of functionally graded material (FGM) was applied in the fabrication process of PEN (Positive-Electrolyte-Negative), the core component of solid oxide fuel cell (SOFC). To enhance its electrochemical performance, the functionally graded PEN of planar SOFC was prepared by atmospheric plasma spray (APS). The cross-sectional SEM micrograph and element energy spectrum of the resultant PEN were analyzed. Its interface

Wei-sheng XIA; Yun-zhen YANG; Hai-ou ZHANG; Gui-lan WANG

2009-01-01

291

Synthesis of cadmium oxide doped ZnO nanostructures using electrochemical deposition  

Microsoft Academic Search

Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. Crystalline nanostructures\\/nanorods with cadmium concentration ranging from 4 to 16at% in the initial solution were electrodeposited on tin doped indium oxide (ITO) conducting glass substrates at a constant cathodic potential ?0.9V and subsequently annealed in air at 300°C. X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and

Trilok Singh; D. K. Pandya; R. Singh

2011-01-01

292

Controllable synthesis of metal hydroxide and oxide nanostructures by ionic liquids assisted electrochemical corrosion method  

Microsoft Academic Search

Cu(OH)2 nanowires have been synthesized by anodic oxidation of copper through a simple electrolysis process employing ionic liquid as an electrolyte. Controlling the electrochemical conditions can qualitatively modulate the lengths, amounts, and shapes of Cu(OH)2 nanostructures. A rational mechanism based on coordination self-assembly and oriented attachment is proposed for the selective formation of the polycrystalline Cu(OH)2 nanowires. In addition, the

N. Liu; D. Wu; Haoxi Wu; Fang Luo; J. Chen

2008-01-01

293

Effect of oxygen non-stoichiometry on the electrochemical performance of lithium manganese oxide spinels  

Microsoft Academic Search

The effect of oxygen non-stoichiometry on the electrochemical performance of lithium manganese oxide spinels is investigated. Spinels with different oxygen contents are obtained from citrate gel synthesis followed by calcination in air in the temperature range 200–850°C. Spinels that were formed at low temperatures are found suitable for 3V applications, whereas those formed at high temperatures perform better at 4V.

A. R Naghash; Jim Y Lee

2001-01-01

294

Electrochemical properties of lithium manganese oxides with different surface areas for lithium ion batteries  

Microsoft Academic Search

Two lithium manganese oxides, Li1.03Mn1.96O4, with different surface areas of 3.55 and 0.68m2\\/g were prepared and their electrochemical properties were studied as positive electrodes for lithium ion batteries. Cycle performance tests gave capacity losses of 9 and 18% at 25°C, and 28 and 33% at 55°C for the samples with larger and smaller surface areas, respectively. The recovery of capacity

Koh Takahashi; Motoharu Saitoh; Norimitsu Asakura; Takashi Hibino; Mitsuru Sano; Miho Fujita; Koich Kifune

2004-01-01

295

Kinetics of ultrasound-enhanced electrochemical oxidation of diuron on boron-doped diamond electrodes  

Microsoft Academic Search

Freshwater polluted with herbicides is an environmental problem of concern due to the high toxicity and non-biodegradability of these compounds. This work analyses for the first time the degradation and mineralization of diuron (N-(3,4-dichlorophenyl)-N,N-dimethyl-urea), considered priority substance by the European Commission, by electrochemical oxidation (EO) at a boron-doped diamond anode enhanced by low frequency (20kHz) ultrasound (US). A synergistic analysis

Eugenio Bringas; Juan Saiz; Inmaculada Ortiz

2011-01-01

296

Observation of ferromagnetic order in electrochemically oxidated La2CuO4+?  

NASA Astrophysics Data System (ADS)

Direct magnetization studies by a SQUID magnetometer of electrochemically oxidated La2CuO4+? were performed. It has been found that enrichment of the samples by excess oxygen leads to appearence of weak ferromagnetic order. It is shown that the ferromagnetic vector is perpendicular to the CuO planes. Evolution of magnetic properties upon variation of the excess oxygen content was investigated.

Garif'yanov, N. N.; Vavilova, E. L.

1997-08-01

297

Electrochemical oxidation behavior of nitrite on a chitosan-carboxylated multiwall carbon nanotube modified electrode  

Microsoft Academic Search

A novel chitosan-carboxylated multiwall carbon nanotube modified glassy carbon electrode (MC\\/GCE) was developed to investigate the oxidation behavior of nitrite using cyclic voltammetry and differential pulse voltammetry modes. The electrochemical mechanism of the MC\\/GCE towards nitrite was discussed. The MC\\/GCE exhibited fast response towards nitrite with a detection limit of 1×10?7moll?1 and a linear range of 5×10?7–1×10?4moll?1. The possible interference

Lingyan Jiang; Ruixia Wang; Xinming Li; Liping Jiang; Guanghan Lu

2005-01-01

298

Electrochemical oxidation of poly(3,4-ethylenedioxythiophene) — “in situ” conductivity and spectroscopic investigations  

Microsoft Academic Search

Electrochemical oxidation of poly(3,4-ethylenedioxythiophene) (PEDOT) is investigated by cyclic voltammetry combined with “in situ” conductivity measurements, UV-vis–NIR and Raman spectroelectrochemical studies. The results seem to indicate that the doping can be adequately described by a heterogeneous “two-phase” model in which the doped conducting phase grows on the expense of the undoped, neutral phase. The extension of the scanning potential to

M. ?apkowski; A. Pro?

2000-01-01

299

Anodic oxidation of titanium and TA6V alloy in chromic media. An electrochemical approach  

Microsoft Academic Search

In order to optimise anodisation surface treatment of titanium alloys, the electrochemical conditions of anodic oxidation of pure titanium and of a TA6V (Ti-6% Al-4% V) alloy were investigated. Both voltametric (potentio-dynamic) and chrono-amperometric (constant voltage, either applied directly or progressively increased during the first steps of the treatment) experiments are conducted. The electrolyte is a chromic acid (CA) (0.5

V Zwilling; M Aucouturier; E Darque-Ceretti

1999-01-01

300

Planar electrochemical sensors based on tape-cast YSZ layers and oxide electrodes  

Microsoft Academic Search

Electrochemical planar sensors based on yttria-stabilized zirconia (YSZ) with semiconducting oxides (WO3 and LaFeO3) and mixed conductors (La0.8Sr0.2FeO3) as sensing electrodes were investigated. The electromotive force (EMF) of the sensors was measured at fixed temperature (450–700 °C) and different concentrations of NO2 and CO in air in the range 20–1000 ppm. The sensors were wholly exposed to the same gas

Elisabetta Di Bartolomeo; Narin Kaabbuathong; Maria Luisa Grilli; Enrico Traversa

2004-01-01

301

Electrochemical and electrochromic behavior of reactively sputtered nickel oxide  

Microsoft Academic Search

Nickel oxide thin films were deposited by reactive sputtering in a 20% oxygen\\/argon atmosphere for use as oxygen evolution catalysts in the photoelectrochemical production of hydrogen. The optical properties of the films were also characterized to evaluate their application as window layers. The polycrystalline films deposited at residual gas pressures of 6 or 10 mTorr exhibited moderate activity for oxygen

Eric L. Miller; R. E. Rocheleau

1997-01-01

302

Comparative study of the destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans during Fenton and electrochemical oxidation of landfill leachates.  

PubMed

Two advanced oxidation processes (AOPs) that provide a broad-spectrum contaminant destruction option were applied to the treatment of the leachates, namely electrochemical and Fenton oxidation. Despite the similar efficiency in the oxidation of major organic contaminants, approximately 90% reduction of chemical oxygen demand after 180 min, our results showed a different behaviour of both AOPs in the oxidation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). A concentration reduction of 73% for 1,2,3,4,6,7,8-HpCDD and of 71% for OCDD was reached after 180 min of electrochemical oxidation and the total toxic equivalent of the sample was reduced in 58%. However, Fenton oxidation followed a different trend and for similar operation times, it was detected an increase in the concentration of several PCDD/Fs congeners, specially stressed for the major congeners 1,2,3,4,6,7,8-HpCDD, OCDD and OCDF, and in the total toxicity of the sample between 12.5% and 128%. Comparison of the results and the rationale behind their difference are finally discussed. PMID:22939898

Vallejo, M; San Román, M F; Irabien, A; Ortiz, I

2012-08-30

303

Iridium and ruthenium complexes covalently bonded to carbon surfaces by means of electrochemical oxidation of aromatic amines  

Microsoft Academic Search

Bis(2-phenylpyridinate-C2,N)-(4-(4-aminophenyl)-2,2?-bipyridine) iridium(III) hexafluorophosphate and bis(2,2?-bipyridine-N,N?)-(4-(4-aminophenyl)-2,2?-bipyridine) ruthenium(II) hexafluorophosphate were synthesized and characterized. In particular, electrochemical analyses showed irreversible amine-centred oxidations, which were exploited to functionalize a glassy carbon electrode. The functionalization was achieved by electrochemical oxidation of the amino group.Surface modification was observed and studied via electrochemical techniques (cyclic voltammetry, square wave voltammetry).The functionalization was performed at different potential values, and

Martina Sandroni; Giorgio Volpi; Jan Fiedler; Roberto Buscaino; Guido Viscardi; Luciano Milone; Roberto Gobetto; Carlo Nervi

2010-01-01

304

A new class of electrochemically and thermally stable lithium salts for lithium battery electrolytes. 4: Investigations of the electrochemical oxidation of lithium organoborates  

SciTech Connect

Synthesis, analysis, and purification of lithium bis[2,2{prime}-biphenyldiolato(2-)-O,O{prime}]borate, lithium bis[salicylato(2-)]-borate, lithium phenolate, and dilithium-2,2{prime}-biphenyldiolate are described. Electrochemical studies show that lithium organoborates are subject to anodic decomposition mechanisms, which depend on their chemical structure. The anodic decomposition of lithium benzenediolatoborates results in the formation of soluble products including chinones, whereas the anodic oxidation of lithium bis[2,2{prime}-biphenyldiolato(2-)-O,O{prime}]borate, lithium bis[salicylato(2-)]borate, and lithium phenolates entails the formation of thin electronically insulating lithium ion-conducting polymer films, preventing further anion decomposition as well as anodic decomposition of solvents which are sensitive to oxidation. These film-forming materials are useful to enlarge the electrochemical window of electrolyte solutions for lithium batteries and electrochemical capacitors.

Barthel, J.; Buestrich, R.; Gores, H.J.; Schmidt, M.; Wuehr, M. [Univ. Regensburg (Germany). Inst. fuer Theoretische und Physikalische Chemie

1997-11-01

305

Electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices  

NASA Astrophysics Data System (ADS)

The focus of this dissertation is the electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices. The electrochemical reduction of metal oxides to metals has been studied for decades as an alternative to pyrometallurgical processes for the metallurgy industry. However, the previous work was conducted on bulk polycrystalline metal oxides. Paper I in this dissertation shows that epitaxial face-centered cubic magnetite (Fe3O4 ) thin films can be electrochemically reduced to epitaxial body-centered cubic iron (Fe) thin films in aqueous solution on single-crystalline Au substrates at room temperature. This technique opens new possibilities to produce special epitaxial metal/metal oxide heterojunctions and a wide range of epitaxial metallic alloy films from the corresponding mixed metal oxides. Electrodeposition, like biomineralization, is a soft solution processing method which can produce functional materials with special properties onto conducting or semiconducting solid surfaces. Paper II in this dissertation presents the electrodeposition of cobalt-substituted magnetite (CoxFe3-xO4, 0 of cobalt-substituted magnetite (CoxFe3-xO4, 0oxide (Co3O4) thin films on stainless steel and Au single-crystalline substrates. The crystalline Co3O4 thin films exhibit high catalytic activity towards the oxygen evolution reaction in an alkaline solution. A possible application of the electrodeposited Co 3O4 is the fabrication of highly active and low-cost photoanodes for photoelectrochemical water-splitting cells.

He, Zhen

306

Electrochemical oxidation and protein adduct formation of aniline: a liquid chromatography/mass spectrometry study.  

PubMed

Historically, skin sensitization tests are typically based on in vivo animal tests. However, for substances used in cosmetic products, these tests have to be replaced according to the European Commission regulation no. 1223/2009. Modification of skin proteins by electrophilic chemicals is a key process associated with the induction of skin sensitization. The present study investigates the capabilities of a purely instrumental setup to determine the potential of commonly used non-electrophilic chemicals to cause skin sensitization by the generation of electrophilic species from the parent compound. In this work, the electrophiles were generated by the electrochemical oxidation of aniline, a basic industrial chemical which may also be released from azo dyes in cosmetics. The compound is a known sensitizer and was oxidized in an electrochemical thin-layer cell which was coupled online to electrospray ionization-mass spectrometry. The electrochemical oxidation was performed on a boron-doped diamond working electrode, which is able to generate hydroxyl radicals in aqueous solutions at high potentials. Without any pretreatment, the oxidation products were identified by electrospray ionization/time-of-flight mass spectrometry (ESI-ToF-MS) using their exact masses. A mass voltammogram was generated by plotting the obtained mass spectra against the applied potential. Oligomerization states with up to six monomeric units in different redox states of aniline were observed using this setup. This approach was extended to generate adducts between the oxidation products of aniline and the tripeptide glutathione. Two adducts were identified with this trapping experiment. Protein modification was carried out subsequently: Aniline was oxidized at a constant potential and was allowed to react with ?-lactoglobulin A (?-LGA) or human serum albumin (HSA), respectively. The generated adducts were analyzed by liquid chromatography coupled to ESI-ToF-MS. For both ?-LGA and HSA, aniline adducts were successfully generated and identified. PMID:22227746

Melles, Daniel; Vielhaber, Torsten; Baumann, Anne; Zazzeroni, Raniero; Karst, Uwe

2012-01-08

307

The electrochemical oxidation of chalcopyrite in ammoniacal solutions  

NASA Astrophysics Data System (ADS)

The anodic dissolution of chalcopyrite in ammoniacal solutions was investigated using electrochemical methods. At low overvoltages, the formation of a copper deficient sulfide layer, Cu1-xFeS2 through a charge transfer reaction is proposed based upon the dependence of the rest or open circuit potential on solution composition and the presence of a Tafel region of appropriate slope. In addition, a current peak that occurs at 10-4 A/cm2 is a function of the square root of the voltage scanning speed and is explained in terms of a charge transfer reaction. At larger overvoltages, constant potential experiments and mass balances performed at various anodic potentials indicate that the dissolution is consistent with the overall reaction, CuFeS2 + 4NH3 + 9OH- = Cu(NH3){4/+2} + Fe(OH)3 + S2O{3/=} + 3H2O + 9e -, although some copper may be released to solution in the cuprous state and some ferrous iron has been identified in the product film. Current vs time data taken during constant potential experiments were found to obey a linear rate relationship. This was interpreted in terms of the formation of a layer of constant thickness which is corroded at the outer interface at the same rate it is formed at the inner interface.. The model proposed is typical of the corrosion of some metals. An examination of the polarization curves shows the dissolution reaction to be first order with respect to [OH-]. The lack of dependence on [Cu2+] indicates that the catalytic effect of cupric ion during oxygen pressure leaching is related only to the cathodic reduction of O2 in agreement with the results of previous investigations.

Warren, G. W.; Wadsworth, M. E.

1984-06-01

308

Electrochemical oxidation of cyanide in the hydrocyclone cell  

SciTech Connect

A diluted electroplating cyanide rinse water has been used to test the use of the hydrocyclone cell (HCC) in batch recycle mode of operation for the simultaneous oxidation of cyanide during the electrodeposition of silver. The results obtained in this work with regard to the final products, current efficiency and the number of transferred electrons per CN{sup {minus}} helped to establish a probable reaction scheme. According to this, the process occurs mainly with one-electron transfer, through cyanate and cyanogen as intermediate species. Meanwhile, under conditions where the electrolyte circulates in an open bath and flows successively through the cathodic and the anodic compartments, as in the case of the HCC system, the cyanate could be produced by the direct oxidation through air and/or generated peroxide and CN could be lost as HCN (g).

Dhamo, N. [TU Berlin (Germany). Inst. fuer Metallurgie

1996-12-31

309

Method of making sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells  

DOEpatents

An electrochemical apparatus is made containing an exterior electorde bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

Isenberg, Arnold O. (Pittsburgh, PA)

1989-01-01

310

Electrochemical oxidation of the carbide wastes of hard alloys using alternating current  

NASA Astrophysics Data System (ADS)

The electrochemical oxidation of the carbide wastes of a W-Co alloy has been studied by gas, electron-probe microanalysis, and X-ray diffraction analyses. The experiments are carried out using halfwave sinusoidal alternating current. It is established that a CO2 + CO mixture forms under such conditions in a gaseous phase in volumetric ratio of 2: 1 and that a tungsten deposit forms in an anode sludge mainly in the form of hydrated tungsten oxide WO2(OH)2. Marketable products are obtained in the form of pure CO3O4 and WO3.

Bryukvin, V. A.; Palant, A. A.; Levchuk, O. M.; Tsybin, O. I.

2012-03-01

311

An electrochemical study of the surface oxidation of arsenopyrite in alkaline media  

Microsoft Academic Search

The electrochemical behavior of arsenopyrite (FeAsS) electrodes in alkaline cyanide solutions has been investigated in an\\u000a attempt to gain a better understanding of its dissolution chemistry. Surface oxidation reactions of arsenopyrite have been\\u000a studied using cyclic voltammetry for pH values between 8.1 and 12.0 and for cyanide concentration from 10-4 to 10-2 M. Anodic oxidation of FeAsS appears to be

Victor Sanchez; J. Brent Hiskey

1988-01-01

312

Electrochemical oxidation of titanium by pulsed discharge in electrolyte  

Microsoft Academic Search

We propose a high-voltage (>1000V) pulsed discharge method of preparation of thin anodic films on valve metals under conditions of extremely high rates of the film growth. The peculiarities of this method have been demonstrated on the anodic oxidation of titanium in sulfuric acid solutions.A light flash at the electrode was generated upon the pulsed anodization of titanium. The emission

S. K. Poznyak; D. V. Talapin; A. I. Kulak

2005-01-01

313

Electrochemical regeneration of Fe 2+ in Fenton oxidation processes  

Microsoft Academic Search

This study is to establish optimal conditions for the minimization of iron sludge produced in Fenton oxidation processes by electro-regenerating Fe2+ with constant potential (CPM) or constant current mode (CCM). Results indicate that the optimal cathodic potential for Fe2+ regeneration is ?0.1V vs. the saturated calomel electrode (SCE) in terms of current efficiency. Keeping the initial Fe3+ concentration ([Fe3+]0) constant,

Zhimin Qiang; Jih-Hsing Chang; Chin-Pao Huang

2003-01-01

314

Electrochemical characterization of commercial lithium manganese oxide powders  

Microsoft Academic Search

Five commercial lithium manganese oxide powders have been studied. The XRD spectra showed all samples to exhibit the spinel structure. The composition and morphology were analyzed by Jaeger–Vetter titration and scanning electron microscopy. The lithium intercalation\\/de-intercalation characteristics and the cycleability have been studied using state-of-the-art cells. The morphology of the particles and crystallites, as well as the defect structure of

H. Huang; C. H. Chen; R. C. Perego; E. M. Kelder; L. Chen; J. Schoonman; W. J. Weydanz; D. W. Nielsen

2000-01-01

315

Development of advanced mixed oxide fuels for plutonium management  

Microsoft Academic Search

A number of advanced Mixed Oxide (MOX) fuel forms are currently being investigated at Los Alamos National Laboratory that have the potential to be effective plutonium management tools. Evolutionary Mixed Oxide (EMOX) fuel is a slight perturbation on standard MOX fuel, but achieves greater plutonium destruction rates by employing a fractional nonfertile component. A pure nonfertile fuel is also being

S. Eaton; C. Beard; J. Buksa; D. Butt; K. Chidester; G. Havrilla; K. Ramsey

1997-01-01

316

Advanced oxidation processes (AOP) for water purification and recovery  

Microsoft Academic Search

All advanced oxidation processes (AOP) are characterised by a common chemical feature: the capability of exploiting the high reactivity of HO radicals in driving oxidation processes which are suitable for achieving the complete abatement and through mineralization of even less reactive pollutants. The different AOP are considered and critically presented according to their specific features with reference, whenever possible, to

Roberto Andreozzi; Vincenzo Caprio; Amedeo Insola; Raffaele Marotta

1999-01-01

317

An entirely electrochemical preparation of a nano-structured cobalt oxide electrode with superior redox activity  

NASA Astrophysics Data System (ADS)

A nano-structured Co oxide electrode (with a Ni substrate) was successfully prepared using an entirely electrochemical process, which included the co-deposition of a Ni-Cu alloy film, selective etching of Cu from the film, and anodic deposition of Co oxide on the obtained nano-porous Ni substrate which had an average pore size of approximately 100 nm and a pore density of about 1013 m-2. The excellent electrochemical activity of the prepared electrode was demonstrated in terms of its pseudocapacitive performance, which was evaluated using cyclic voltammetry (CV) in 1 M KOH solution. The specific capacitance of the nano-structured Co oxide measured at a potential scan rate of 10 mV s-1 was as high as 2200 F g-1, which is over ten times higher than that of a flat oxide electrode (209 F g-1). The highly porous Co oxide also had superior kinetic performance as compared to a flat electrode. At a high CV scan rate of 50 mV s-1, the two electrodes retained 94% and 59%, respectively, of their specific capacitances measured at 5 mV s-1.

Deng, Ming-Jay; Huang, Fu-Lu; Sun, I.-Wen; Tsai, Wen-Ta; Chang, Jeng-Kuei

2009-04-01

318

A new preparation method of LaMnO3 perovskite using electrochemical oxidation  

NASA Astrophysics Data System (ADS)

LaMnO3 perovskite was prepared by heat treatment of an oxide film which was electrochemically deposited on a Pt electrode in solutions containing both La3+ and Mn2+ ions. The La/Mn ratio in the deposited oxide films increased with an increase in the [La3+]/[Mn2+] ratio in solution and with a positive shift of electrode potential. The maximum value in this ratio was about one, and was obtained in solution with [La3+]/[Mn2+] > 500 and/or in a potential region more positive than about 1.9 V vs. Ag/AgCl. It was presumed from IR, TG, XRD, and XPS measurements that the incorporation of La3+ ion into the oxide film during electrochemical deposition is based on a specific adsorption of La3+ ions onto the surface of amorphous and hydrous ?-MnO2, which has some oxygen deficiencies, and that the La3+ ion exists as a hydroxide in the oxide. A single phase of LaMnO3 perovskite was obtained by heat-treatment of the deposited oxide film with La/Mn ? 1.0 at a temperature higher than about 750°C, which was always lower than the preparation temperature in the ceramic technique (about 1200°C). The crystallization process in the heat treatment was also discussed from TG and XRD analysis.

Sasaki, Takeshi; Matsumoto, Yasumichi; Hombo, Jukichi; Ogawa, Yoriyuki

1991-03-01

319

A comparative study on oxidation of disperse dyes by electrochemical process, ozone, hypochlorite and Fenton reagent.  

PubMed

The results of an experimental study on the destruction of disperse dyes by chemical oxidation using ozone, hypochlorite and Fenton reagent (H2O2 + Fe2+) are compared with the data obtained by electrochemical oxidation. While the results obtained during hypochlorite oxidation were not satisfactory (only 35% reduction of colour was achieved at a dose of 6 g dm(-3)), ozonation enabled colour to be reduced by up to 90% (ozone dose 0.5 g dm(-3)). A high decolourisation degree was however accompanied by a low removal (10% efficiency) of chemical oxygen demand (COD). Trials of electrochemical oxidation proved this process much more efficient. Under the conditions of an acidic pH in 40 min of electrolysis a 79% elimination of COD was achieved at the Ti/Pt-Ir anode, which proved the best of seven different tested materials. Simultaneously 90% colour was removed. Indirect oxidation, by means of chlorine-deriving compounds, was the predominating process leading to the pollutants depletion. The best treatment results were obtained with the Fenton process, which under the optimal pH equal to 3 and hydrogen peroxide and ferrous sulphide dose of 600 and 550 mg dm(-3), respectively, resulted in a final effluent being colourless and with the residual COD equal to 100 mg dm(-3). PMID:11358291

Szpyrkowicz, L; Juzzolino, C; Kaul, S N

2001-06-01

320

Charge Transport Properties of P3HT-PEO block copolymers that are Electrochemically Oxidized in the Solid-State  

NASA Astrophysics Data System (ADS)

We report on the relationship between morphology and electronic/ionic charge transport of Poly(3-hexylthiophene)-b-Poly(ethylene oxide) (P3HT-b-PEO) and lithium bis-(trifluoromethanesulfonyl) imide (LiTFSI) mixtures. Using ac impedance spectroscopy, we show that P3HT-b-PEO/LiTFSI mixtures can conduct electronic and ionic charges simultaneously. The electronic resistance of P3HT-b-PEO can be controlled through the electrochemical oxidation of P3HT with LiTFSI. We designed an all solid-state electrochemical cell with three terminals to measure the electronic conductivity of P3HT-b-PEO under applied potentials. The addition of a third terminal within the P3HT-b-PEO layer allows for the in-situ measurement of the electronic conductivity as a function of the P3HT electrochemical oxidation level. Our experimental setup is unique in that electrochemical oxidation occurs in the presence of solid-polymer electrolyte. Previous studies on the electrochemical oxidation of polythiophenes have been done in the presence of a liquid electrolyte. The results of the in-situ electronic conductivity measurements as a function of electrochemical doping level and block copolymer composition will be presented.

Patel, Shrayesh; Javier, Anna; Balsara, Nitash

2013-03-01

321

Zinc oxide/redox mediator composite films-based sensor for electrochemical detection of important biomolecules.  

PubMed

Electrochemical oxidation of serotonin (SN) onto zinc oxide (ZnO)-coated glassy carbon electrode (GCE) results in the generation of redox mediators (RMs) that are strongly adsorbed on electrode surface. The electrochemical properties of zinc oxide-electrogenerated redox mediator (ZnO/RM) (inorganic/organic) hybrid film-coated electrode has been studied using cyclic voltammetry (CV). The scanning electron microscope (SEM), atomic force microscope (AFM), and electrochemical techniques proved the immobilization of ZnO/RM core/shell microparticles on the electrode surface. The GCE modified with ZnO/RM hybrid film showed two reversible redox peaks in acidic solution, and the redox peaks were found to be pH dependent with slopes of -62 and -60 mV/pH, which are very close to the Nernst behavior. The GCE/ZnO/RM-modified electrode exhibited excellent electrocatalytic activity toward the oxidations of ascorbic acid (AA), dopamine (DA), and uric acid (UA) in 0.1M phosphate buffer solution (PBS, pH 7.0). Indeed, ZnO/RM-coated GCE separated the anodic oxidation waves of DA, AA, and UA with well-defined peak separations in their mixture solution. Consequently, the GCE/ZnO/RMs were used for simultaneous detection of DA, AA, and UA in their mixture solution. Using CV, calibration curves for DA, AA, and UA were obtained over the range of 6.0 x 10(-6) to 9.6 x 10(-4)M, 1.5 x 10(-5) to 2.4 x 10(-4)M, and 5.0 x 10(-5) to 8 x 10(-4)M with correlation coefficients of 0.992, 0.991, and 0.989, respectively. Moreover, ZnO/RM-modified GCE had good stability and antifouling properties. PMID:18577367

Tang, Chun-Fang; Kumar, S Ashok; Chen, Shen-Ming

2008-06-07

322

Electrochemical carbon nanotube filter oxidative performance as a function of surface chemistry.  

PubMed

An electrochemical carbon nanotube filter has been reported to be effective for the removal and electrooxidation of aqueous chemicals and microorganisms. Here, we investigate how carbon nanotube (CNT) chemical surface treatments including calcination to remove amorphous carbon, acid treatment to remove internal residual metal oxide, formation of surficial oxy-functional groups, and addition of Sb-doped SnO(2) particles affect the electrooxidative filter performance. The various CNT samples are characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) and electrochemically evaluated by cyclic voltammetry, open circuit potential versus time analysis, and electrochemical impedance spectroscopy. Voltammetry results indicate that the near CNT surface pH is at least two units lower than the bulk pH. The electrooxidative performance of the various CNT samples is evaluated with 1 mM of methyl orange (MO) in 100 mM sodium sulfate at a flow rate of 1.5 mL min(-1). At both 2 and 3 V, the efficacy of electrochemical filtration is observed to be function of CNT surface chemistry. The samples with the greatest electrooxidation were the calcinated then HCl-treated CNTs, i.e., the CNTs with the most surficial sp(2)-bonded carbon, and the Sb-SnO(2)-coated CNTs, i.e., the CNTs with the most electrocatalytic surface area. At 3 V applied voltage, these CNT samples are able to oxidize 95% of the influent MO within the liquid residence time of <1.2 s. The broader applicability of electrochemical filtration is evaluated by challenging the C-CNT-HCl and C-CNT-HNO(3) networks with various organics including methylene blue, phenol, methanol, and formaldehyde. At 3 V applied voltage, both CNTs are able to degrade a fraction of all the organics with the extent organic degradation dependent on both CNT and organic properties. The C-CNT-HCl network generally had the better oxidative performance than the C-CNT-HNO(3) network with an exception being the positively charged methylene blue. The extent of MO degradation, steady-state current, anode potential, effluent pH, and back pressure are also measured as a function of applied voltage (1-3 V) and CNT surface chemistry. Mass spectrometry of electrochemical CNT filter effluent at 2 and 3 V is utilized to evaluate plausible electrooxidation products. Energy consumption as compared to state-of-the-art electrodes and strategies to tailor the CNT surface for a specific target molecule are discussed. PMID:21967752

Gao, Guandao; Vecitis, Chad D

2011-10-24

323

Localized electrochemical oxidation of thin Nb Films in microscopic and nanoscopic dimensions  

NASA Astrophysics Data System (ADS)

The mechanism and kinetics of localized anodic oxidation of thin Nb films are investigated by measurements in an electrochemical microcell and in the so-called nanocell, which is formed by water condensation between an AFM-tip and the Nb-substrate in humid air. In both, the microscopic and nanoscopic oxidation, the thickness of generated oxide structures increases linearly with the applied potential in accordance with the so-called high field growth model. The oxide growth factor depends on the polarization time and reaches in both cases for long times a value of about 2.8 nm/V. In the case of AFM tip-induced oxidation at constant voltage the oxide growth rate decreases rapidly with the polarization time, which is in good agreement with the proposed models including a rapid build-up of space charge within the oxide in the initial oxidation stages. The increase of the oxide thickness is limited by the thickness of the thin Nb layer. An experimental procedure for checking the complete local nanooxidation of thin Nb films is proposed and the possibility for preparation of lateral metal insulator metal (MIM) structures is demonstrated.

Heidelberg, A.; Rozenkranz, C.; Schultze, J. W.; Schäpers, Th.; Staikov, G.

2005-12-01

324

Electrochemically-Controlled Compositional Oscillations of Oxide Surfaces  

SciTech Connect

Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically and/or ionically conducting, and thus they have been used in a number of solid-state devices such as solid oxide fuel cells and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface chemistries is crucial to enhance device performance. In this study, we demonstrate that the surface strontium (Sr) and cobalt (Co) concentrations of perovskite-based thin films can be controlled reversibly at elevated temperatures by applying small electrical potential biases. The surface chemistry changes of La0.8Sr0.2CoO3 (LSC113), LaSrCoO4 (LSC214), and LSC214-decorated LSC113 films (LSC113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr was found for the LSC113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites.

Mutoro, Eva [Massachusetts Institute of Technology (MIT); Crumlin, Ethan [Massachusetts Institute of Technology (MIT); Pöpke, Hendrik [Institute of Physical Chemistry, Justus-Liebig-University Giessen; Luerssen, Bjoern [Institute of Physical Chemistry, Justus-Liebig-University Giessen; Amati, Matteo [Sincrotrone Trieste Elettra; Abyaneh, Majid [Sincrotrone Trieste, Basovizza, Italy; Biegalski, Michael D [ORNL; Christen, Hans M [ORNL; Gregoratti, Luca [Sincrotrone Trieste, Basovizza, Italy; Janek, Jürgen [Institute of Physical Chemistry, Justus-Liebig-University Giessen; Shao-Horn, Yang [Massachusetts Institute of Technology (MIT)

2012-01-01

325

Efficient electrochemical oxidation of perfluorooctanoate using a Ti/SnO2-Sb-Bi anode.  

PubMed

The electrochemical decomposition of persistent perfluorooctanoate (PFOA) with a Ti/SnO2-Sb-Bi electrode was demonstrated in this study. After 2 h electrolysis, over 99% of PFOA (25 mL of 50 mg·L(-1)) was degraded with a first-order kinetic constant of 1.93 h(-1). The intermediate products including short-chain perfluorocarboxyl anions (CF3COO-, C2F5COO-, C3F7COO-, C4F9COO-, C5F11COO-, and C6F13COO-) and F- were detected in the aqueous solution. The electrochemical oxidation mechanism was revealed, that PFOA decomposition first occurred through a direct one electron transfer from the carboxyl group in PFOA to the anode at the potential of 3.37 V (vs saturated calomel electrode, SCE). After that, the PFOA radical was decarboxylated to form perfluoroheptyl radical which allowed a defluorination reaction between perfluoroheptyl radical and hydroxyl radical/O2. Electrospray ionization (ESI) mass spectrum further confirmed that the oxidation of PFOA on the Ti/SnO2-Sb-Bi electrode proceeded from the carboxyl group in PFOA rather than C-C cleavage, and the decomposition processes followed the CF2 unzipping cycle. The electrochemical technique with the Ti/SnO2-Sb-Bi electrode provided a potential method for PFOA degradation in the aqueous solution. PMID:21361321

Zhuo, Qiongfang; Deng, Shubo; Yang, Bo; Huang, Jun; Yu, Gang

2011-03-01

326

Electrochemical oxidation of amides of type Ph2CHCONHAr.  

PubMed

Anodic oxidation of N-aryl-2,2-diphenylacetamides in acetonitrile undergoes three types of bond-cleavage, one between the benzylic carbon and the carbonyl group, the second between a carbonyl and 'N', and the third between the 'N' atom and aryl group. The selectivity of the cleavage and nature of emerged products is highly dependent on the nature of substituent attached to the aryl group. For example, electron-withdrawing groups direct the benzyl-carbonyl bond-breaking whereas electron-donating substituents favor the N-aryl bond cleavage. The type of products obtained involve benzophenone, 2,2-diphenylacetamide, N-(diphenylmethylene)acetamide, N-(diphenylmethyl)acetamide, ?-lactam (1-acetyl-3,3-diphenylaziridin-2-one, as a 1 : 1 complex with 2,4-dinitroaniline) and aniline derivatives. PMID:22476115

Golub, Tatiana; Becker, James Y

2012-04-04

327

Competitive electrochemical oxidation of p-chlorophenol and p-nitrophenol on Bi-doped PbO 2  

Microsoft Academic Search

The initial stages of oxidation of aqueous solutions of p-chlorophenol (pcp) and p-nitrophenol (pnp) on Bi-doped PbO2 electrodes have been studied. From deconvolution and analysis of UV–Vis spectra of the solutions obtained during electrochemical oxidation, benzoquinone and aliphatic acids were identified as the primary oxidation intermediates; oxidation of benzoquinone was found to be the slow step during the early stages

C. Borras; T. Laredo; B. R. Scharifker

2003-01-01

328

Tetradentate Schiff base ligands and their complexes: synthesis, structural characterization, thermal, electrochemical and alkane oxidation.  

PubMed

Three Schiff base ligands (H(2)L(1)-H(2)L(3)) with N(2)O(2) donor sites were synthesized by condensation of 1,5-diaminonapthalene with benzaldehyde derivatives. A series of Cu(II), Co(II), Ni(II), Mn(II) and Cr(III) complexes were prepared and characterized by spectroscopic and analytical methods. Thermal, electrochemical and alkane oxidation reactions of the ligands and their metal complexes were investigated. Extensive application of 1D ((1)H, (13)C NMR) and 2D (COSY, HETCOR, HMBC and TOSCY) NMR techniques were used to characterize the structures of the ligands and establish the (1)H and (13)C resonance assignments of the three ligands. Ligands H(2)L(1) and H(2)L(3) were obtained as single crystals from THF solution and characterized by X-ray diffraction. Both molecules are centrosymmetric and asymmetric unit contains one half of the molecule. Catalytic alkane oxidation reactions with the transition metal complexes investigated using cyclohexane and cyclooctane as substrates. The Cu(II) and Cr(III) complexes showed good catalytic activity in the oxidation of cyclohexane and cyclooctane to desired oxidized products. Electrochemical and thermal properties of the compounds were also investigated. PMID:22571942

Ceyhan, Gökhan; Köse, Muhammet; McKee, Vickie; Uru?, Serhan; Gölcü, Ay?egül; Tümer, Mehmet

2012-04-21

329

Tetrathiafulvalene-oligo(para-phenyleneethynylene) conjugates: formation of multiple mixed-valence complexes upon electrochemical oxidation.  

PubMed

Short monodisperse oligo- (para-phenyleneethynylene) (pOPE) units bearing laterally attached tetrathio-substituted tetrathiofulvalene (TTF) units have been synthesised from functionalised aromatic building blocks by using the Sonogashira cross-coupling methodology. The unusual redox properties of these TTF-pOPE conjugates were observed by employing electrochemical methods, such as cyclic voltammetry and exhaustive electrolysis. We found that formally one half of the TTF units in the pOPE monomer 1, dimer 2, and trimer 3 (with 2, 4, and 6 TTF units, respectively) are electrochemically silent during the first-step oxidation at 0.49?V. We propose the formation of persistent mixed-valence complexes from the TTF and TTF(+·) units present in an equal ratio. Such mixed-valence dyads (single or multiple in the partially oxidised 1-3) exhibit an unusual stability towards oxidation until the potential of the second oxidation at 0.84?V is achieved. This finding suggests that below this potential the oxidation of the respective mix-valence complexes is extremely slow. PMID:23495131

Lipnická, Šárka; B?lohradský, Martin; Kolivoška, Viliam; Pospíšil, Lubomír; Hromadová, Magdaléna; Pohl, Radek; Chocholoušová, Jana Vacek; Vacek, Jaroslav; Fiedler, Jan; Stará, Irena G; Starý, Ivo

2013-03-13

330

Development of an Electrochemical Oxidation Method for Probing Higher Order Protein Structure with Mass Spectrometry  

SciTech Connect

We report here the novel use of electrochemistry to generate covalent oxidative labels on intact proteins in both non-native and physiologically relevant solutions as a surface mapping probe of higher order protein structure. Two different electrodes were tested across a range of experimental parameters including voltage, flow rate, and solution electrolyte composition to affect the extent of oxidation on intact proteins, as measured both on-line and off-line with mass spectrometry. Oxidized proteins were collected off-line for proteolytic digestion followed by LC-MS/MS analysis. Peptide MS/MS data were searched with the InsPecT scoring algorithm for forty-six oxidative mass shifts previously reported in the literature. Preliminary data showed agreement between solvent accessibility and the oxidation status of many ubiquitin residues in aqueous buffer, while more buried residues were found to be oxidized in non-native solution. Our results indicate that electrochemical oxidation using a boron-doped diamond electrode has the potential to become a useful and easily accessible tool for conducting oxidative surface mapping experiments.

McClintock, Carlee [ORNL; Kertesz, Vilmos [ORNL; Hettich, Robert {Bob} L [ORNL

2008-01-01

331

Electroless Deposition of Conformed Nanoscale Iron Oxide on Carbon Nanoarchitectures for Electrochemical Charge Storage  

SciTech Connect

We describe a simple self-limiting electroless deposition process whereby conformal, nanoscale iron oxide (FeO{sub x}) coatings are generated at the interior and exterior surfaces of macroscopically thick ({approx}90 {micro}m) carbon nanofoam paper substrates via redox reaction with aqueous K{sub 2}FeO{sub 4}. The resulting FeO{sub x}-carbon nanofoams are characterized as device-ready electrode structures for aqueous electrochemical capacitors and they demonstrate a 3-to-7 fold increase in charge-storage capacity relative to the native carbon nanofoam when cycled in a mild aqueous electrolyte (2.5 M Li{sub 2}SO{sub 4}), yielding mass-, volume-, and footprint-normalized capacitances of 84 F g{sup -1}, 121 F cm{sup -3}, and 0.85 F cm{sup -2}, respectively, even at modest FeO{sub x} loadings (27 wt %). The additional charge-storage capacity arises from faradaic pseudocapacitance of the FeO{sub x} coating, delivering specific capacitance >300 F g{sup -1} normalized to the content of FeO{sub x} as FeOOH, as verified by electrochemical measurements and in situ X-ray absorption spectroscopy. The additional capacitance is electrochemically addressable within tens of seconds, a time scale of relevance for high-rate electrochemical charge storage. We also demonstrate that the addition of borate to buffer the Li{sub 2}SO{sub 4} electrolyte effectively suppresses the electrochemical dissolution of the FeO{sub x} coating, resulting in <20% capacitance fade over 1000 consecutive cycles.

Sassin, M.; Mansour, A; Pettigrew, K; Rolison, D; Long, J

2010-01-01

332

High performance solid oxide fuel cell cathode fabricated by electrochemical vapor deposition  

SciTech Connect

La(Sr)MnO[sub 3] cathodes have been investigated as high temperature oxygen reduction electrodes in the solid oxide fuel cells (SOFCs). The cathodes consist of 10 mole percent of yttria stabilized zirconia (YSZ) thin film electrolyte layer deposited on a porous La[sub 0.81]Sr[sub 0.09]MnO[sub 3] tube using the electrochemical vapor deposition method. The La(Sr)MnO[sub 3]/YSZ cathodes have different electrochemical properties from those fabricated with the sintering method. The cathode polarization was about 1 mV at a current density of 1.5 A/cm[sup 2] in oxygen at 1,000 C. This type of cathode has an extremely large phase boundary and large interfacial capacitance (more than 1 F/cm[sup 2]) which is approximately proportional to the oxygen partial pressure.

Suzuki, Minoru; Sasaki, Hirokazu; Otoshi, Shoji; Kajimura, Atsuko; Sugiura, Nozomi; Ippommatsu, Masamichi (Osaka Gas Co. Ltd. (Japan). Fundamental Research Labs.)

1994-07-01

333

Electrochemical Regeneration of a Spent Oxidizing Solution: Example of a Clean Chemical Process  

NASA Astrophysics Data System (ADS)

This paper describes a simple laboratory experiment suitable for degree courses in chemistry or chemical engineering. It is very easy to carry out and provides a simple demonstration of the utility of the electrochemical methodology. It consists of two stages. The first is obtaining benzaldehyde by oxidation of benzyl alcohol using a solution of potassium dichromate in sulfuric acid. Analysis by gas chromatography is used to monitor the reaction. After work-up, the second stage, the electrochemical regeneration of the chromium(VI) solution, using a filter press type reactor, is accomplished. Visible spectrophotometry is used to monitor the chromium species solution. A 96% material yield in electrolysis for the regeneration of the chromium(VI) solution was obtained. This means that at the end of the experiment, the initial chromium(VI) solution is nearly recovered and shows the possibility of using chromium(VI) in a closed cycle without generating hazardous effluents.

Ingles, M.; Bonete, P.; Expósito, E.; García-García, V.; González-Garcia, J.; Iniesta, J.; Montiel, V.

1999-10-01

334

Changes in the redox state of iridium oxide clusters and their relation to catalytic water oxidation. Radiolytic and electrochemical studies  

SciTech Connect

Radiolytically prepared iridium oxide (IrO{sub x}{center dot}nH{sub 2}O) clusters have been shown to catalyze the photochemical oxidation of water. These catalysts have been oxidized by radiolytic or electrochemical methods and the changes in their optical absorptions and redox states have been studied. The clusters contain four or five Ir atoms in a mixture of Ir{sup III} and Ir{sup IV} states, formally described as Ir{sup 3.2+}. Time-resolved pulse-radiolytic studies revealed three processes in the subsecond time scale. The first step produces a short-lived intermediate ({lambda}{sub max} {approximately} 360 nm), possibly an OH adduct, that is transformed to more stable oxidized species ({lambda}{sub max} 340 and 580 nm). In the third step, there is a rise in the 580-nm absorption. The same species were observed in {gamma}-radiolysis and in spectroelectrochemical experiments. Cyclic voltammetric and coulometric measurements suggest that the initial IrO{sub x} cluster is oxidized in two stages, from Ir{sup 3.2+} to Ir{sup 3.8+} and then to Ir{sup 4+}. Further oxidation of the cluster leads to oxidation of water to O{sub 2}.

Nahor, G.S.; Hapiot, P.; Neta, P. (National Institute of Standards and Technology, Gaithersburg, MD (USA)); Harriman, A. (Univ. of Texas, Austin (USA))

1991-01-24

335

Advanced oxidation processes coupled with electrocoagulation for the exhaustive abatement of Cr-EDTA.  

PubMed

Using Cr-EDTA as a model system, a two-step method has been investigated for the abatement of persistent chromium complexes in water. The treatment consists of an oxidative decomposition of the organic ligands by means of ozonization or electrochemical oxidation at a boron doped diamond (BDD) electrode, followed by removal of the metal via electrochemical coagulation. In the designed synthetic waste, EDTA has been used both as a chelating agent and as a mimic of the organic content of a typical wastewater provided by a purification leather plant. A crucial point evaluated is the influence of the oxidative pretreatment on the chemical modification of the synthetic waste and hence on the electrocoagulation efficacy. Because of the great stability of Cr complexes, such as Cr-EDTA, the classical coagulation methods, based on ligand exchange between Cr(III) and Fe(II) or Fe(III), are ineffective toward Cr abatement in the presence of organic substances. On the contrary, when advanced oxidation processes (AOPs), such as ozonization or electrooxidation at a BDD anode are applied in series with electrocoagulation (EC), complete abatement of the recalcitrant Cr fraction can be achieved. ECs have been carried out by using Fe sacrificial anodes, with alternating polarization and complete Cr abatement (over 99%) has been obtained with modest charge consumption. It has been found that Cr(III) is first oxidized to Cr(VI) in the AOP preceding EC. Then, during EC, Cr(VI) is mainly reduced back to Cr(III) by electrogenerated Fe(II). Thus, Cr is mainly eliminated as Cr(III). However, a small fraction of Cr(VI) goes with the precipitate as confirmed by XPS analysis of the sludge. PMID:21255817

Durante, Christian; Cuscov, Marco; Isse, Abdirisak Ahmed; Sandonà, Giancarlo; Gennaro, Armando

2010-12-28

336

The kinetics of the oxidation of pyrite by ferric ions and dissolved oxygen: an electrochemical study  

NASA Astrophysics Data System (ADS)

The dissolution of pyrite is important in the geochemical cycling of iron and sulphur, in the formation of acid mine drainage, and in the extraction of metals by bacterial leaching. Many researchers have studied the kinetics of dissolution, and the rate of dissolution has often been found to be half-order in ferric ions or oxygen. Previous work has not adequately explained the kinetics of dissolution of pyrite. The dissolution of pyrite is an oxidation-reduction reaction. The kinetics of the oxidation and reduction half-reactions was studied independently using electrochemical techniques of voltammetry. The kinetics of the overall reaction was studied by the electrochemical technique of potentiometry, which consisted of measuring the mixed potential of a sample of corroding pyrite in solutions of different compositions. The kinetics of the half reactions are related to the kinetics of the overall dissolution reaction by the condition that there is no accumulation of charge. This principle is used to derive expressions for the mixed potential and the rate of dissolution, which successfully describe the mixed potential measurements and the kinetics of dissolution reported in the literature. It is shown that the observations of half-order kinetics and that the oxygen in the sulphate product arises from water are both a direct consequence of the electrochemical mechanism. Thus it is concluded that the electrochemical reaction steps occurring at the mineral-solution interface control the rate of dissolution. Raman spectroscopy was used to analyze reaction products formed on the pyrite surface. The results indicated that small amounts of polysulphides form on the surface of the pyrite. However, it was also found that the mixed (corrosion) potential does not change over a 14-day leaching period. This indicates that even though polysulphide material is present on the surface, it does not influence the rate of the reactions occurring at the surface. Measurements of the sulphur yields as a function of electrode potential indicate that thiosulphate is not the only source of the sulphur product.

Holmes, Paul R.; Crundwell, Frank K.

2000-01-01

337

Electrochemical synthesis of magnetic iron oxide nanoparticles with controlled size.  

PubMed

We present a novel and facile method enabling synthesis of iron oxide nanoparticles, which are composed mainly of maghemite according to X-ray diffraction (XRD) and Mössbauer spectroscopy studies. The proposed process is realized by anodic iron polarization in deaerated LiCl solutions containing both water and ethanol. Water seems to play an important role in the synthesis. Morphology of the product was studied by means of transmission electron microscopy and XRD. In the solution containing almost 100% of water a black suspension of round shaped maghemite nanoparticles of 20-40 nm size is obtained. Regulating water concentration allows to control nanoparticle size, which is reduced to 4-6 nm for 5% of water with a possibility to reach intermediate sizes. For 3% or lower water concentration nanoparticles are of a needle-like shape and form a reddish suspension. In this case phase determination is problematic due to a small particle size with the thickness of roughly 3 nm. However, XRD studies indicate the presence of ferrihydrite. Coercivities of the materials are similar to those reported for nanoparticle magnetite powders, whereas the saturation magnetization values are considerably smaller. PMID:22207821

Starowicz, Maria; Starowicz, Pawe?; Zukrowski, Jan; Przewo?nik, Janusz; Lema?ski, Andrzej; Kapusta, Czes?aw; Bana?, Jacek

2011-11-27

338

Assessment of detoxification of microcystin extracts using electrochemical oxidation.  

PubMed

Microcystins, cyclic heptapeptide toxins produced by cyanobacteria, possess tumor-promoting activity, which act through inhibition of protein phosphatases 1 and 2A. In this study, the variation in toxicity of microcystins from Microcystis aeruginosa during electrooxidation was assessed using bioassays. The microcystin-LR samples (MCLR) were prepared by crude extracts dissolved in electrolytes, e.g., 0.02 mol L(-1) Na(2)SO(4), 0.02 mol L(-1) Na(2)SO(4) containing 0.5 mmol L(-1) NaCl, and tap water. Electrooxidation was conducted at a current density of 4 mA cm(-2) at room temperature (20-26°C), using Ti/RuO(2) anodes. Toxicological profiles for acute toxic effects (Vibrio fischeri) and genotoxic effects (Vicia faba micronucleus assay and single cell gel electrophoresis assay of mice lymphocytes) were determined for both untreated and treated MCLR samples. Results showed that acute toxicity during treatment was caused mainly by residual oxidants from electrooxidation. The by-products from the degradation of MCLR samples showed very weak acute toxicity to V. fischeri. Before electrooxidation, MCLR samples could induce obvious cell damage to V. faba root tips and mice lymphocytes. Electrooxidation degradation significantly decreased the genotoxicity of MCLR samples until the final by-products showed no toxicity. Thus, electrooxidation can detoxify MCLR samples via degradation processes. PMID:21806454

Liang, Wenyan; Chen, Li; Sui, Lili; Yu, Jian; Wang, Li; Shi, Hongxing

2011-01-01

339

Evaluation by electrochemical impedance spectroscopy of a process of removal of iron oxides deposited on a heat exchanger tubing  

Microsoft Academic Search

The formation of iron oxides layers over the tubes of a heat exchanger is a phenomenon that can make heat transfer difficult. A chemical process has been proposed for removing these iron oxides layers formed on Inconel 600 tubes. Electrochemical impedance spectroscopy is used as a tool for studying the different experimental conditions of this process. In this paper, the

J AbellÀ; J BarcelÓ; L Victori

1998-01-01

340

Determination of photo conversion efficiency of nanotubular titanium oxide photo-electrochemical cell for solar hydrogen generation  

Microsoft Academic Search

Anodized and annealed titanium oxide nanotubes show enhanced photo activity and can be used as photo anodes for water electrolysis in hydrogen generation. Application of an external potential to the photo anode is required for enhancement of the photocurrent. This additional electrical energy input complicates the photo conversion efficiency calculation. In this investigation, the photo-electrochemical behavior of anodized titanium oxide

K. S. Raja; V. K. Mahajan; M. Misra

2006-01-01

341

Zinc oxide quantum dots synthesized by electrochemical etching of metallic zinc in organic electrolyte and their electrochemiluminescent properties  

Microsoft Academic Search

A universal and facile electrochemical etching method for synthesizing nanosized metal oxide semiconductors has been presented by taking the synthesis of ZnO quantum dots (QDs) from metallic zinc as an example. By applying an appropriate potential, metallic zinc was controllably oxidized to Zn2+ ion, the latter (Zn2+) was released into an organic electrolyte and hydrolyzed by trace dissolved water therein,

Lichan Chen; Nengna Xu; Haiyan Yang; Chen Zhou; Yuwu Chi

2011-01-01

342

Materials for electrochemical capacitors  

NASA Astrophysics Data System (ADS)

Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

Simon, Patrice; Gogotsi, Yury

2008-11-01

343

Cobalt (hydro)oxide electrodes under electrochemical conditions: a first principle study  

NASA Astrophysics Data System (ADS)

There is currently much interest in photoelectrochemical water splitting as a promising pathway towards sustainable energy production. A major issue of such photoelectrochemical devices is the limited efficiency of the anode, where the oxygen evolution reaction (OER) takes place. Cobalt (hydro)oxides, particularly Co3O4 and Co(OH)2, have emerged as promising candidates for use as OER anode materials. Interestingly, recent in-situ Raman spectroscopy studies have shown that Co3O4 electrodes undergo progressive oxidation and transform into oxyhydroxide, CoO(OH), under electrochemical working conditions. (Journal of the American Chemical Society 133, 5587 (2011))Using first principle electronic structure calculations, we provide insight into these findings by presenting results on the structural, thermodynamic, and electronic properties of cobalt oxide, hydroxide and oxydroxide CoO(OH), and on their relative stabilities when in contact with water under external voltage.

Chen, Jia; Selloni, Annabella

2013-03-01

344

New advanced surface modification technique: titanium oxide ceramic surface implants: long-term clinical results  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to discuss the background to advanced surface modification technologies and to present a new technique, involving the formation of a titanium oxide ceramic coating, with relatively long-term results of its clinical utilization. Three general techniques are used to modify surfaces: the addition or removal of material and the change of material already present. Surface properties can also be changed without the addition or removal of material, through the laser or electron beam thermal treatment. The new technique outlined in this paper relates to the production of a corrosion-resistant 2000-2500 A thick, ceramic oxide layer with a coherent crystalline structure on the surface of titanium implants. The layer is grown electrochemically from the bulk of the metal and is modified by heat treatment. Such oxide ceramic-coated implants have a number of advantageous properties relative to implants covered with various other coatings: a higher external hardness, a greater force of adherence between the titanium and the oxide ceramic coating, a virtually perfect insulation between the organism and the metal (no possibility of metal allergy), etc. The coated implants were subjected to various physical, chemical, electronmicroscopic, etc. tests for a qualitative characterization. Finally, these implants (plates, screws for maxillofacial osteosynthesis and dental root implants) were applied in surgical practice for a period of 10 years. Tests and the experience acquired demonstrated the good properties of the titanium oxide ceramic-coated implants.

Szabo, Gyorgy; Kovacs, Lajos; Barabas, Jozsef; Nemeth, Zsolt; Maironna, Carlo

2001-11-01

345

Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy  

Microsoft Academic Search

The effect of the SnO2 nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified

Mihrican Muti; Arzum Erdem; Ayfer Caliskan; Ali S?nag; Tugrul Yumak

2011-01-01

346

Electrochemical oxidation and cleavage of tyrosine- and tryptophan-containing tripeptides.  

PubMed

Electrochemical oxidation of peptides and proteins has been shown to lead to specific cleavage next to tyrosine (Tyr) and tryptophan (Trp) residues which makes the coupling of electrochemistry to mass spectrometry (EC-MS) a potential instrumental alternative to chemical and enzymatic cleavage. A set of Tyr and Trp-containing tripeptides has been studied to investigate the mechanistic aspects of electrochemical oxidation and the subsequent chemical reactions including peptide bond cleavage, making this the first detailed study of the electrochemistry of Trp-containing peptides. The effect of adjacent amino acids was studied leading to the conclusion that the ratios of oxidation and cleavage products are peptide-dependent and that the adjacent amino acid can influence the secondary chemical reactions occurring after the initial oxidation step. The effect of parameters such as potential and solvent conditions showed that control of the oxidation potential is crucial to avoid dimer formation for Tyr and an increasing number of oxygen insertions (hydroxylations) for Trp, which occur above 1000 mV (vs Pd/H(2)). While the formation of reactive intermediates after the first oxidation step is not strongly dependent on experimental conditions, an acidic pH is required for good cleavage yields. Working under strongly acidic conditions (pH 1.9-3.1) led to optimal cleavage yields (40-80%), whereas no or little cleavage occurred under basic conditions. Online EC-MS allowed determining the optimal potential for maximum cleavage yields, whereas EC-LC-MS/MS revealed the nature and distribution of the reaction products. PMID:20726506

Roeser, Julien; Permentier, Hjalmar P; Bruins, Andries P; Bischoff, Rainer

2010-09-15

347

Complete treatment of olive pomace leachate by coagulation, activated-carbon adsorption and electrochemical oxidation.  

PubMed

A battery scheme comprising sequential alum coagulation, activated-carbon adsorption and electrochemical oxidation over boron-doped diamond electrodes to mineralize a leachate from olive pomace processing is demonstrated. The effect of coagulant and adsorbent concentration on treatment efficiency was assessed in the range 0.1-50 mM Al(3+) and 2.5-50 g/L activated-carbon and optimal conditions were established. Coagulation at 7.5mM Al(3+) resulted in substantial solids and color removal (i.e. 80% and 93%, respectively). This was accompanied by only 30% chemical oxygen demand (COD) reduction (initial COD was about 3,500 mg/L). The latter increased to 80% though when coagulation was coupled with adsorption at 25 g/L activated carbon. Electrochemical oxidation of the original effluent for 360 min led to 63% and 82% COD reduction at 10 and 20A current intensity, respectively. When this process was tested as a polishing stage following coagulation and adsorption, overall COD removal reached values of 92% and 97%, respectively. The final effluent was also colorless and solids free. However, the treated effluent still exhibited ecotoxicity possibly due to the formation of ecotoxic oxidation products. PMID:18396309

Mavros, Michael; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios; Diamadopoulos, Evan

2008-03-04

348

Structure and Electrochemical Properties of Cobalt Oxide Films Grown by Pulsed Laser Deposition (PLD)  

NASA Astrophysics Data System (ADS)

We report the growth of amorphous and high quality crystalline CoO and Co_3O4 thin films by PLD from a CoO target. A phase diagram for PLD growth of cobalt oxide from a CoO target has been mapped out using X-ray diffraction and Raman spectroscopy. The films have also been evaluated as cathodes for high energy density Li batteries. Unlike LiCoO_2, an excellent cathode, these materials do not lithiate effectively. Electrochemical lithiation of an amorphous cobalt oxide film yields a maximum Li intercalation ratio of Li:Co=0.08. In the crystalline Co_3O4 and CoO films, the Li:Co ratio is 0.004 or smaller. Typical LiCoO2 cathodes have a reversible Li intercalation ratio of Li:Co=1.0. For crystalline CoO and Co_3O_4, a lack of appropriate channels may explain the low Li intercalation levels. As a contrast, Li intercalation ratios of 1.09 are obtainable for V_2O5 which has larger channels(J.G. Zhang, J.M.McGraw, J.A. Turner, D.S. Ginley, J. Electrochem. Soc., submitted (1996)). Current work focuses on the in-situ growth and evaluation of additional cobalt oxide phases as well as LiCoO_2.

Fu, M. L.; Rogers, C. T.; Perkins, J. D.; McGraw, J. M.; Ginley, D. S.; Parilla, P. A.; Zhang, J. G.; Turner, J. A.

1997-03-01

349

Electrochemical sulfide oxidation from domestic wastewater using mixed metal-coated titanium electrodes.  

PubMed

Hydrogen sulfide generation is a major issue in sewer management. A novel method based on electrochemical sulfide oxidation was recently shown to be highly effective for sulfide removal from synthetic and real sewage. Here, we compare the performance of five different mixed metal oxide (MMO) coated titanium electrode materials for the electrochemical removal of sulfide from domestic wastewater. All electrode materials performed similarly in terms of sulfide removal, removing 78±5%, 77±1%, 85±4%, 84±1%, and 83±2% at a current density of 10 mA/cm(2) using Ta/Ir, Ru/Ir, Pt/Ir, SnO(2) and PbO(2), respectively. Elevated chloride concentrations, often observed in coastal areas, did not entail any significant difference in performance. Independent of the electrode material used, sulfide oxidation by in situ generated oxygen was the predominant reaction mechanism. Passivation of the electrode surface by deposition of elemental sulfur did not occur. However, scaling was observed in the cathode compartment. This study shows that all the MMO coated titanium electrode materials studied are suitable anodic materials for sulfide removal from wastewater. Ta/Ir and Pt/Ir coated titanium electrodes seem the most suitable electrodes since they possess the lowest overpotential for oxygen evolution, are stable at low chloride concentration and are already used in full scale applications. PMID:21885081

Pikaar, Ilje; Rozendal, René A; Yuan, Zhiguo; Keller, Jürg; Rabaey, Korneel

2011-08-06

350

Monitoring charge storage processes in nanoscale oxides using electrochemical scanning probe microscopy.  

SciTech Connect

Advances in electrochemical energy storage science require the development of new or the refinement of existing in situ probes that can be used to establish structure - activity relationships for technologically relevant materials. The drive to develop reversible, high capacity electrodes from nanoscale building blocks creates an additional requirement for high spatial resolution probes to yield information of local structural, compositional, and electronic property changes as a function of the storage state of a material. In this paper, we describe a method for deconstructing a lithium ion battery positive electrode into its basic constituents of ion insertion host particles and a carbon current collector. This model system is then probed in an electrochemical environment using a combination of atomic force microscopy and tunneling spectroscopy to correlate local activity with morphological and electronic configurational changes. Cubic spinel Li{sub 1+x}Mn{sub 2-x}O{sub 4} nanoparticles are grown on graphite surfaces using vacuum deposition methods. The structure and composition of these particles are determined using transmission electron microscopy and Auger microprobe analysis. The response of these particles to initial de-lithiation, along with subsequent electrochemical cycling, is tracked using scanning probe microscopy techniques in polar aprotic electrolytes (lithium hexafluorophosphate in ethylene carbonate:diethylcarbonate). The relationship between nanoparticle size and reversible ion insertion activity will be a specific focus of this paper.

Zavadil, Kevin Robert; Lu, Ping; Huang, Jian Yu

2010-11-01

351

Electrochemical oxidation of saline industrial wastewaters using boron-doped diamond anodes  

Microsoft Academic Search

Similarly to other catalytic advanced oxidation processes electro-oxidation by means of boron-doped diamond (BDD) anodes generates a very efficient oxidant media containing, among others, hydroxyl radicals. In this work BDD electro-oxidation is demonstrated to be an efficient alternative to treat a wide variety of saline industrial effluents, which main properties were as follows: TOC=266–4479mg\\/L; [N-NH3]=61–1150mg\\/L; [Cl?]=1996–37,645mg\\/L; conductivity=5.6–64mS\\/cm. Experiments were conducted

Angela Anglada; Raquel Ibañez; Ane Urtiaga; Inmaculada Ortiz

2010-01-01

352

Combinatorial electrochemical synthesis and characterization of tungsten-molybdenum mixed metal oxides  

Microsoft Academic Search

Automated systems for electrochemical synthesis and high throughput screening of photoelectrochemical materials were developed\\u000a and used to prepare tungsten-molybdenum mixed metal oxides, WO3-MoO3. Two-dimensional arrays (library) of diverse composition were synthesized by automated cathodic electrodeposition on Ti foil\\u000a substrate. Electrolytes were prepared by mixing W-peroxo complex and Mo-peroxo complex. The compositions in films were found\\u000a to strongly depend on the

Sung Hyeon Baeck; Eric W. McFarland

2002-01-01

353

Characteristics of sealed plasma electrolytic oxidation coatings with electrochemical impedance spectroscopy  

NASA Astrophysics Data System (ADS)

Plasma electrolytic oxidation (PEO) coatings are prepared on aluminium with graphite powders added into the electrolyte. The scanning electron microscopy (SEM) coupled with an energy dispersive x-ray analysis system (EDX) is used to characterize the surface and the cross-section morphologies of the coatings. The electrochemical impedance spectroscopy (EIS) is used not only to evaluate the corrosion resistance but also to analyse the structure of the coating. Results show that graphite powders are embedded in the PEO coating. The corrosion resistances of both the inner barrier and the outer porous layer are greatly improved, and the EIS could give some valuable detailed information about the coating structure.

Lü, Guo-Hua; Chen, Huan; Wang, Xing-Quan; Pang, Hua; Zhang, Gu-Ling; Zou, Bin; Lee, Heon-Ju; Yang, Si-Ze

2010-08-01

354

Complete treatment of olive pomace leachate by coagulation, activated-carbon adsorption and electrochemical oxidation  

Microsoft Academic Search

A battery scheme comprising sequential alum coagulation, activated-carbon adsorption and electrochemical oxidation over boron-doped diamond electrodes to mineralize a leachate from olive pomace processing is demonstrated. The effect of coagulant and adsorbent concentration on treatment efficiency was assessed in the range 0.1–50mM Al3+ and 2.5–50g\\/L activated-carbon and optimal conditions were established. Coagulation at 7.5mM Al3+ resulted in substantial solids and

Michael Mavros; Nikolaos P. Xekoukoulotakis; Dionissios Mantzavinos; Evan Diamadopoulos

2008-01-01

355

Reduced graphene oxide paper by supercritical ethanol treatment and its electrochemical properties  

NASA Astrophysics Data System (ADS)

Graphene oxide (GO) paper was treated in supercritical ethanol as a green route for its reduction, which was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis and conductivity measurements. The reduced GO paper showed good electrochemical properties. As a sole component of the anode in lithium ion batteries, its specific capacity was comparable to those of free standing GO papers reduced by hydrazine or carbon nanotube paper. The GO paper reduced by supercritical ethanol can be a potential candidate for a binder-free anode in high performance lithium batteries.

Liu, Siyang; Chen, Ke; Fu, You; Yu, Suyang; Bao, Zhihao

2012-04-01

356

Aqua-Biomant: integrated biological and electrochemical oxidation for industrial wastewater treatment.  

PubMed

An innovative technology for industrial wastewater treatment has been developed. The main focus of the new system is a transformation of persistent organic compounds (biorecalcitrant COD) into a biodegradable fraction, followed by high efficient biological elimination using specialised bacteria's. To fulfill these targets the Aqua-Biomant process integrates two treatment steps: an aerated biological upflow filter and a electrochemical oxidation technique using boron doped-diamond electrodes. The advantages of the process are high efficient COD removal with reduced energy consumption combined with low total residence time. PMID:17674848

Rüdiger, A; Rüdiger, I; Jurisevic, L

2007-01-01

357

Nonlinear dynamical analysis of spike generation in electrochemical oxidation of formic acid on Pt  

NASA Astrophysics Data System (ADS)

A nonlinear dynamical analysis is made for the generation of potential spikes in response to the change in the current in the electrochemical oxidation of formic acid on Pt, based on a mechanistic model. This model assumes the potential-dependent adsorption, desorption, and reaction of the adsorbed water and carbon monoxide. The model is found to reproduce the spikes observed experimentally in a previous report. The trajectory of the state point in the state space shows how and why the system generates spikes.

Naito, Masayoshi; Okamoto, Hiroshi; Tanaka, Naoki

2000-03-01

358

Oscillations and period-doubling bifurcations in the electrochemical oxidation of thiourea  

NASA Astrophysics Data System (ADS)

The electrochemical oxidation of thiourea on a Pt electrode was found to exhibit both simple and period-doubled oscillations. Measurements of the potentiostatic I/Ø behavior and impedance spectra suggest that the studied system belongs to the hidden negative differential resistance (HNDR) oscillator. The dependence of complex oscillations on initial compositions of the reaction mixture and temperature has also been characterized, which showed that: (1) lowering the reaction temperature facilitates the occurrence of complex oscillations; (2) the frequency of oscillation increases linearly with respect to the temperature; and (3) hydrochloric acid exhibits stronger influence on the reaction behavior than nitric acid.

Xu, Liangqin; Gao, Qingyu; Feng, Jiamin; Wang, Jichang

2004-10-01

359

The cooperative electrochemical oxidation of chlorophenols in anode–cathode compartments  

Microsoft Academic Search

By using a self-made carbon\\/polytetrafluoroethylene (C\\/PTFE) O2-fed as the cathode and Ti\\/IrO2\\/RuO2 as the anode, the degradation of three organic compounds (phenol, 4-chlorophenol, and 2,4-dichlorophenol) was investigated in the diaphragm (with terylene as diaphragm material) electrolysis device by electrochemical oxidation process. The result indicated that the concentration of hydrogen peroxide (H2O2) was 8.3mg\\/L, and hydroxyl radical (HO) was determined in

Hui Wang; Jian Long Wang

2008-01-01

360

TREATMENT OF COMPLEX SYSTEMS ADVANCED OXIDATION PROCESSES  

Microsoft Academic Search

\\u000a Many water streams, both wastewater effluents and drinking8 water sources, contain pollutants that cannot be removed or destroyed\\u000a by conventional physical or biological treatment processes. In such cases it is necessary to seek alternatives. One approach\\u000a is to destroy the pollutant by application of a strong oxidizing agent. Chlorine is one candidate reagent, but it can produce\\u000a undesirable reaction products,

THOMAS W. CHAPMAN

361

Characterization of electro-oxidation catalysts using scanning electrochemical and mass spectral methods  

NASA Astrophysics Data System (ADS)

Low temperature fuel cells have many potential benefits, including high efficiency, high energy density and environmental friendliness. However, logistically appealing fuels for this system, such as reformed hydrocarbons or alcohols, exhibit poor performance because of catalyst poisoning that occurs during oxidation at the anode. This research focuses on the analysis of several model fuels and catalyst materials to understand the impact of catalyst poisoning on reactivity. Two novel experimental tools were developed based upon the local measurement of catalyst performance using scanning, reactivity mapping probes. The Scanning Electrochemical Microscope (SECM) was used to directly measure the rate constant for hydrogen oxidation in the presence and absence of dissolved CO. The Scanning Differential Electrochemical Mass Spectrometer (SDEMS) was exploited to measure the partial and complete oxidation products of methanol and ethanol oxidation. The reactivity of Pt and Pt/Ru catalysts towards the hydrogen oxidation reaction in the absence and presence of adsorbed CO was elucidated using the SECM. Steady state rate constant measurements in the absence of CO showed that the rate of hydrogen oxidation reaction exceeded 1 cms-1 . Steady state rate constant measurements in the presence of CO indicated that the platinum surface is completely inactive due to adsorbed CO. Addition of as little as 6% Ru to the Pt electrode was found to significantly improve the activity of the electrode towards CO removal. SDEMS was used to study the electro-oxidation of methanol on Pt xRuy electrodes at different electrode potentials and temperatures. Screening measurements performed with the SDEMS showed that PtxRu y electrodes containing 6--40% Ru had the highest activity for methanol oxidation. Current efficiencies for CO2 were also calculated under different conditions. SDEMS was also used to study the electro-oxidation of ethanol on Pt xRuy electrodes. The reaction was found to occur more slowly than the methanol oxidation reaction. Addition of 22%--40% Ru to the Pt electrode was found to increase the current densities and lower the onset potentials. The reaction was found to occur though a parallel path mechanism, which was confirmed by the detection of ethanol and acetic acid apart from CO2.

Jambunathan, Krishnakumar

362

An electrochemical capacitor electrode based on porous carbon spheres hybrided with polyaniline and nanoscale ruthenium oxide.  

PubMed

Nanoscopic ruthenium oxide (RuO(2))/polyaniline (PANI)/carbon double-shelled hollow spheres (CS) composites, RuO(2)/PANI/CS, have been prepared via electro-polymerization of aniline and redox deposition of RuO(2) on the surface of CS. The structures and morphologies of the resulting ternary composites are characterized using scanning electron microscopy (SEM), infrared spectroscopy (IR), energy-dispersive X-ray spectroscopy (EDX). The electrochemical properties of the ternary composites as active electrode materials for electrochemical capacitors have been investigated by different electrochemical techniques including cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy. The results show that the specific capacitance of RuO(2)/PANI/CS composites is 531 F g(-1) at 1 mA cm(-2) in 1.0 M H(2)SO(4) electrolyte, which is higher than many other currently available ternary composites based on RuO(2)/PANI. At the same time, the composites display a good rate capability and 70% of the initial specific capacitance is retained with the charge-discharge current density up to 10 mA cm(-2). PMID:22988980

Zhao, Dan; Guo, Xinying; Gao, Yue; Gao, Feng

2012-10-02

363

Graphene oxide sheet-mediated silver enhancement for application to electrochemical biosensors.  

PubMed

Functionalized graphene oxide (GO) sheets coupled with a signal amplification method based on the nanomaterial-promoted reduction of silver ions for the sensitive and selective detection of bacteria. This paper aims to develop an electrochemical route combined with GO sheet-mediated Ag enhancement for biological/chemical analyte detection. A linear relationship between the stripping response and the logarithm of the bacterial concentration was obtained using an electrochemical technique for concentrations ranging from 1.8 × 10(2) to 1.8 × 10(8) cfu mL(-1), with a slope of 15.28 and a correlation coefficient of 0.995. Dot blot assay was used as a conventional immunoassay method for comparison with the electrochemical method, as well as to observe the quality of the anti-sulfate-reducing bacteria (SRB) antibody (Ab) used in the immunosensor. The GO sheet-mediated silver enhancement holds great potential for the rapid analysis of protein, DNA, and pathogens. PMID:21175166

Wan, Yi; Wang, Yi; Wu, Jiajia; Zhang, Dun

2010-12-22

364

Rapid online nonenzymatic protein digestion combining microwave heating acid hydrolysis and electrochemical oxidation.  

PubMed

We report an online nonenzymatic method for site-specific digestion of proteins to yield peptides that are well suited for collision-induced dissociation tandem mass spectrometry. The method combines online microwave heating acid hydrolysis at aspartic acid and online electrochemical oxidation at tryptophan and tyrosine. The combined microwave/electrochemical digestion is reproducible and produces peptides with an average sequence length of 10 amino acids. This peptide length is similar to the average peptide length of 9 amino acids obtained by digestion of proteins with the enzyme trypsin. As a result, the peptides produced by this novel nonenzymatic digestion method, when analyzed by electrospray ionization mass spectrometry, produce protonated molecules with mostly +1 and +2 charge states. The combination of these two nonenzymatic methods overcomes shortcomings with each individual method in that (i) peptides generated by the microwave-hydrolysis method have an average amino acid length of 16 amino acids and (ii) the electrochemical-cleavage method is unable to reproducibly digest proteins with molecular masses above 4 kDa. Preliminary results are presented on the application and utility of this rapid online digestion (total of 6 min of digestion time) on a series of standard peptides and proteins as well as an Escherichia coli protein extract. PMID:21138252

Basile, Franco; Hauser, Nicolas

2010-12-07

365

Rapid Online Non-Enzymatic Protein Digestion Combining Microwave Heating Acid Hydrolysis and Electrochemical Oxidation  

PubMed Central

We report an online non-enzymatic method for site-specific digestion of proteins to yield peptides that are well suited for collision induced dissociation (CID) tandem mass spectrometry (MS/MS). The method combines online microwave heating acid hydrolysis at aspartic acid and online electrochemical oxidation at tryptophan and tyrosine. The combined microwave/electrochemical (microwave/echem) digestion is reproducible and produces peptides with an average sequence length of 10 amino acids. This peptide length is similar to the average peptide length of 9 amino acids obtained by digestion of proteins with the enzyme trypsin. As a result, the peptides produced by this novel non-enzymatic digestion method, when analyzed by ESI-MS, produce protonated molecules with mostly +1 and +2 charge states. The combination of these two non-enzymatic methods overcomes shortcomings with each individual method in that: i) peptides generated by the microwave-hydrolysis method have an average amino acid length of 16 amino acids, and ii) the inability of the electrochemical-cleavage method to reproducibly digest proteins with molecular masses above 4 kDa. Preliminary results are presented on the application and utility of this rapid online digestion (total of 6 min digestion time) on a series of standard peptides and proteins as well as an E. coli protein extract.

Basile, Franco; Hauser, Nicolas

2010-01-01

366

Treatment of gasoline-contaminated waters by advanced oxidation processes  

Microsoft Academic Search

In this study, the efficiency of advanced oxidative processes (AOPs) was investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX) and gasoline-contaminated waters. The results indicated that BTX can be effectively oxidized by near UV-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolic intermediates at

Elaine Regina Lopes Tiburtius; Patricio Peralta-Zamora; Alexandre Emmel

2005-01-01

367

Electrochemical oxidation of La2CuO4 in fused nitrates  

NASA Astrophysics Data System (ADS)

La2CuO4 has been electrochemically oxidized in fused alkali nitrates, a medium that stabilizes peroxo and superoxo groups. The oxidation takes place either in neutral (NaClO4 electrolyte) or basic (KOH, Na2O electrolytes) media, in the presence or absence of protons, and in the presence or absence of added oxo groups (e.g. NaClO4). The oxidation potentials are lower as the basicity of the medium increases (NaClO4 > KOH > Na2O). The resulting La2CuO4+? materials have large superconductivity fractions when the oxidation is performed at 150°C, and very small fractions (along with phase decomposition into CuO) when it is performed at 235°C. The oxidized materials are totally unreactive versus iodide. That, along with the reported existence of peroxo and superoxo groups in this media, suggests that intercalation of oxygen in intermediate -1 and/or - oxidation states takes place. However, the existence of such reaction in the absence of protons eliminates the possibility of a mechanism by which OH- groups are being intercalated. Potentiostatic experiments yield a phase-segregated material with phases of Tc 45 and 35 K, while galvanostatic experiments allow to prepare the 35 K phase by itself.

Michel, C. R.; Casañ-Pastor, N.

1997-02-01

368

Electrochemical oxidation behavior of colchicine on a graphene oxide-Nafion composite film modified glassy carbon electrode.  

PubMed

An electrochemical sensor, based on a graphene oxide (GO)-Nafion composite film modified glassy carbon electrode (GCE), was developed and used for detection of trace amounts of colchicine. Owing to the large surface area, good conductivity of GO and good affinity of Nafion, the sensor exhibited excellent electrocatalytic activity for the oxidation of colchicine, displaying a wide linear response from 5.0 × 10(-8) to 2.0 × 10(-5) mol L(-1) and a low detection limit of 1.5 × 10(-8) mol L(-1) in 0.1 mol L(-1) H(2)SO(4) solution. And this modified electrode exhibited a superior immunity from epinephrine, dopamine and ascorbic acid interference. The method was also applied successfully to detect colchicine in medicinal tablets. PMID:21808780

Wang, Fei; Zhou, Jing; Liu, Yang; Wu, ShengJiang; Song, Ge; Ye, Baoxian

2011-08-02

369

Preliminary evaluation of hybrid electrochemical-thermochemical cycles for the production of hydrogen from water. [Lead oxide cycle  

Microsoft Academic Search

Water decomposition cycles, of the hybrid type, involving an electrochemical cell producing hydrogen, and an oxide, and a subsequent thermochemical process loop which liberates oxygen and regenerates the lower oxide (or metal), are evaluated. A prototype cycle based on the oxides of lead: HO + PbO H + PbO (electrolysis) PbO PbO + ¹\\/O (thermal decomposition) is presented. In principle,

Munger

1976-01-01

370

Electrochemical reduction of porous 17 kg uranium oxide pellets by selection of an optimal cathode\\/anode surface area ratio  

Microsoft Academic Search

This study examines how the cathode\\/anode surface area ratio affects the electrochemical reduction of uranium oxide in a molten Li2O–LiCl electrolyte. A bench-scale test showed that a low cathode\\/anode surface area ratio is helpful for efficiently attaining a high current density and producing metallic uranium from uranium oxide in an Li2O–LiCl electrolyte. A 17kg uranium oxide electrolysis cell was set

Eun-Young Choi; Jin-Mok Hur; In-Kyu Choi; Seon Gil Kwon; Dae-Seung Kang; Sun Seok Hong; Ho-Sup Shin; Min A. Yoo; Sang Mun Jeong

2011-01-01

371

Electrochemical oxidation of PAN and pitch-based carbon fibers and deposition of palladium on the obtained materials  

Microsoft Academic Search

The electrochemical oxidation of polyacrylonitrile (PAN)- and pitch-based carbon fibers and the deposition of palladium on the electro-oxidized materials are comparatively studied. Electrooxidation of both kinds of carbon fibers is achieved by application of alternate anodic and cathodic pulses. Through this procedure cation-exchangeable groups are created on the carbon support. Under the same oxidation conditions the quantity of the cation

E. Theodoridou; A. D. Jannakoudakis; P. D. Jannakoudakis; Ph. Andonoglou; J. O. Besenhard

1997-01-01

372

Effect of oxidation–reduction surface treatment on the electrochemical behavior of PAN-based carbon fibers  

Microsoft Academic Search

The relationship between surface functionality and electrochemical properties of polyacrylonitrile (PAN)-based carbon fibers (CFs) differentiated by the modification treatment was studied. Oxidative and non-oxidative treatments (i.e. oxidation with ammonium peroxydisulfate (1 M (NH4)2S2O8), and heating in hydrogen and argon atmosphere) were used for the modification. The chemical character of the CF surface was estimated by using the titration method and

Yu. V. Basova; H. Hatori; Y. Yamada; K. Miyashita

1999-01-01

373

Pretreatment of whole blood using hydrogen peroxide and UV irradiation. Design of the advanced oxidation process  

PubMed Central

A new process to pretreat blood samples has been developed. This process combines the Advanced Oxidation Process (AOP) treatment (using H2O2 and UV irradiation) with acid deactivation of the enzyme catalase in blood. A four-cell reactor has been designed and built in house. The effect of pH on the AOP process has been investigated. The kinetics of the pretreatment process shows that at high CH2O2,t = 0, the reaction is zeroth order with respect to CH2O2 and first order with respect to Cblood. The rate limiting process is photon flux from the UV lamp. Degradation of whole blood has been compared with that of pure hemoglobin samples. The AOP pretreatment of the blood samples has led to the subsequent determination of chromium and zinc concentrations in the samples using electrochemical methods.

Bragg, Stefanie A.; Armstrong, Kristie C.; Xue, Zi-Ling

2013-01-01

374

Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste  

SciTech Connect

Fracture of AISI 4340 steel in concentrated sodium hydroxide solution has been monitored by measuring the coupling current that flows between the crack and the external surfaces. The results clearly demonstrate that positive current flows from the crack to the external cathodes (through the solution) during crack growth of AISI 4340 steel in concentrated (6 to12 M) sodium hydroxide solution at 70 C. The (electron) coupling current contains periodic noise that is attributed to fracture events occurring at the crack front, with the amplitude of the noise and the mean current increasing with crack growth rate. The characteristic shape of the individual transients in the noise at lower SCC crack growth rate is a rapid drop followed by slow recovery. The form of the noise in the coupling current during SCC at high NaOH concentration (8 M and 12 M) is attributed to overlap of many cracks propagating simultaneously through micro fracture events along grain boundaries. The discrete events, which have a dimension of about 49 {micro}m, are postulated to be hydrogen induced, and the mechanism of caustic cracking of AISI 4340 steel is considered to be hydrogen embrittlement along grain boundaries. Measurement of the electrochemical noise is shown to be capable of detecting and distinguishing between uniform corrosion and stress corrosion cracking in the steel/NaOH system. The coupling current data are consistent with a hydrogen embrittlement mechanism for crack advance.

Macdonald, Digby D.; Liu, Sue; Sikora, Elizbieta; Liu, Jun

2001-06-01

375

Composite electrodes for advanced electrochemical applications. Quarterly report for the period July 1 - September 30, 1999  

SciTech Connect

The electrochemical industry is one of the most highly energy-intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating cost, and the proprietary nature of the technology. In addition, DSAs experience problems that include contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from under attack, generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy-efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.

Kovach, Chris

1999-10-01

376

Composite electrodes for advanced electrochemical applications. Quarterly report for the period October 1, - December 31, 1999  

SciTech Connect

The electrochemical industry is one of the most highly energy intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating costs, and the proprietary nature of the technology. In addition, DSAs experience problems that include: contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from underattack, generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.

Kovach, Chris

2000-01-01

377

Determination of oxide barrier-film thickness of anodized aluminum by electrochemical impedance spectroscopy at the nanometer scale  

NASA Astrophysics Data System (ADS)

In this study, the effect of the annealing treatment on electrochemical behavior and the oxide barrier-film thickness of anodized aluminum-magnesium (Al-Mg) alloy was investigated. Electrochemical parameters such as the polarization resistance (RP), solution resistance (RSol), alternating current impedance (Z), and the double layer capacitance (CdL) of the anodized Al-Mg alloy were determined in sulfuric acid solutions ranged from 0-10% H2SO4 by electrochemical impedance spectroscopy (EIS) methods. Then, the oxide film thickness of the anodized Al-Mg alloy was determined from the obtained electrochemical parameters as a function of the sulfuric acid concentration (0-10% H2SO4), in the as received sample and annealed sample conditions. The optimum thickness of the oxide film was determined for the as received samples (4.2nm) and for the annealed samples (0.63nm) in sulfuric acid concentrations of 4% and 2% H2SO4, respectively. The reason behind the oxide film thickness of the as received samples is greater than the one for the annealed samples, because the former samples are thermodynamically unstable (more chemically active) as compared to the annealed samples. A mathematical model was developed to interpret the mechanism of the oxide film build up on the aluminum substrate. The mathematical model of the oxide film build up on the aluminum substrate was proposed for the next challenge of the present work.

Habib, K.

2010-03-01

378

Electrochemical deposition of iridium (IV) oxide from alkaline solutions of iridium(III) oxide  

Microsoft Academic Search

Cyclic voltammetry is used to deposit films of hydrous iridium oxide onto glassy carbon electrodes from a basic solution of saturated iridium(III) oxide. An acidic solution of Ir(OH2)2Cl4? is first prepared from either IrCl63 or IrCl62?. When this solution is made basic, iridium (IV) oxide is deposited by oxygen generated from oxidation of hydroxide. A strongly adherent, bright blue deposit

John E. Baur; Thomas W. Spaine

1998-01-01

379

Pilot treatment of olive pomace leachate by vertical-flow constructed wetland and electrochemical oxidation: an efficient hybrid process.  

PubMed

A hybrid process comprising biological degradation in a vertical-flow constructed wetland (CW) and electrochemical oxidation over boron-doped diamond electrodes to decolorize, mineralize and detoxify a leachate from olive pomace processing (OPL) was investigated. Two alternative treatment schemes were compared: According to the first treatment scheme, OPL was treated by electrochemical oxidation followed by treatment in a constructed wetland pilot unit (CW-A). The second scheme comprised of treatment in a constructed wetland followed by electrochemical treatment (CW-B). The constructed wetlands units were planted with Phragmites australis (reeds) and were fed intermittently at organic loadings between 5 and 15 g COD m(-2) d(-1) and a residence time of 3 d. Electrochemical oxidation (EO) was performed for 360 min at 20 A. Treatment of OPL in the wetland at 15 g COD m(-2) d(-1) led to mean COD and color reduction of 86% and 77%, respectively; the wetland effluent with a COD of about 800 mg L(-1) was polished electrochemically for 360 min after which the overall COD and color removal of the combined process (i.e. CW-B/EO) was around 95%, while the final effluent was not toxic against the marine bacteria Vibrio fischeri. Electrochemical oxidation of the original OPL at COD values between 6250 and 14 100 mg L(-1) led to moderate COD and color reduction (i.e. less than 40%) through zero order kinetics. When this was coupled to constructed wetland post-treatment (i.e. EO/CW-A), the overall COD and color removal was 81% and 58%, respectively. The decreased efficiency may be assigned to the increased toxicity of the electrochemically treated effluent which was only partially removed in the natural treatment system. PMID:20199791

Grafias, Petros; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios; Diamadopoulos, Evan

2010-02-16

380

Electrochemical and spontaneous deposition of ruthenium at platinum electrodes for methanol oxidation: an electrochemical quartz crystal microbalance study  

Microsoft Academic Search

PtRu electrodes with Ru surface concentration ranging from 20 to 50% were prepared by electrolysis of Ru(NO)(NO3)3 at a constant potential and\\/or by spontaneous Ru deposition performed at open circuit potential from a RuCl3 solution. The amount of either spontaneously or electrochemically deposited ruthenium on the platinum electrode was determined by means of an electrochemical quartz crystal microbalance (EQCM). The

F. Vigier; F. Gloaguen; J.-M. Léger; C. Lamy

2001-01-01

381

Laboratory and pilot plant scale study on the electrochemical oxidation of landfill leachate.  

PubMed

Kinetic data regarding COD oxidation were measured in a laboratory scale cell and used to scale-up an electro-oxidation process for landfill leachate treatment by means of boron-doped diamond anodes. A pilot-scale reactor with a total BDD anode area of 1.05 m(2) was designed. Different electrode gaps in the laboratory and pilot plant cells resulted in dissimilar reactor hydrodynamics. Consequently, generalised dimensionless correlations concerning mass transfer were developed in order to define the mass transfer conditions in both electrochemical systems. These correlations were then used in the design equations to validate the scale-up procedure. A series of experiments with biologically pre-treated landfill leachate were done to accomplish this goal. The evolution of ammonia and COD concentration could be well predicted. PMID:20542632

Anglada, Angela; Urtiaga, Ana M; Ortiz, Inmaculada

2010-06-09

382

Great diversity in stability of perovskite-type oxides studied by electrochemical hydrogen charging  

Microsoft Academic Search

Single crystals of 0.91Pb(Zn1\\/3Nb2\\/3)O3-0.09PbTiO3, SrTiO3 and BaTiO3, and ceramic pellets of CaCu3Ti4O12 and BiFeO3 have been studied and compared through electrochemical hydrogen charging, in which the oxides were coated with silver electrodes\\u000a to electrolyze water as the cathode. Great diversity has been observed in the stability of the oxides: 0.91Pb(Zn1\\/3Nb2\\/3)O3-0.09PbTiO3 was quickly decomposed; hydrogen could enter the lattice of the

Yuchong Pei; Wanping Chen

2011-01-01

383

Electrochemical and electrochromic properties of niobium oxide thin films fabricated by pulsed laser deposition  

SciTech Connect

Niobium oxide thin films have been successfully fabricated on the indium-tin oxide coated glasses by pulsed laser deposition in an O{sub 3}/O{sub 2} gas mixture. Films are characterized by X-ray diffraction and Raman spectrometry. Electrochemical and electrochromic properties of Nb{sub 2}O{sub 5} films are examined by cyclic voltammogram and potential step coupled with an in situ charge-coupled device spectrophotometer. The unique characteristics of absorption spectra of Nb{sub 2}O{sub 5} films are observed for the first time, and the optical absorption from the trapped electrons in the surface states plays an important role in the electrochromic phenomenon.

Fu, Z.W.; Kong, J.J.; Qin, Q.Z.

1999-10-01

384

Evidence of benzilic rearrangement during the electrochemical oxidation of D-glucose to D-glucaric acid.  

PubMed

During the course of the 2,2,6,6-tetramethyl-1-piperidinyloxy free radical-catalyzed electrochemical oxidation of D-glucose to D-glucaric acid a new side-product was observed. This compound was isolated and identified as a tricarboxylic acid of unique structure, which was named maribersonic acid. Its structure was proven by different experiments coupled with several analytical methods, and its appearance during the electrochemical oxidation of D-glucose was rationalized through a thorough study. PMID:21269605

Ibert, Mathias; Fuertès, Patrick; Merbouh, Nabyl; Feasson, Christian; Marsais, Francis

2010-12-30

385

Oxidation of zinc in alkaline solutions studied by electrochemical impedance spectroscopy  

SciTech Connect

Electrochemical dissolution and passivation reactions of zinc have been studied in 1.0 M KOH solutions by electrochemical impedance spectroscopy. Equivalent circuits have been worked out by simulating the impedance data and using the results to model the dissolution and passivation reactions. A Tafel plot constructed from the charge-transfer resistances provides an exchange current of 0.11 A/cm{sup 2} and an {alpha} value of 0.36 for zinc oxidation. The maximum rate of zinc oxidation is observed at about {minus}1.30 V vs. the Hg/HgO reference electrode as judged from the charge-transfer resistance minimum obtained from impedance measurements. A negative polarization resistance with a reverse semicircle on the Nyquist plot illustrates the transition process from an active to passive potential region at {minus}1.10 V. At high anodic over-potentials, the zinc electrode behaved as a semiconductor electrode due to a compact ZnO passive film formed on the electrode surface.

Cai, M.; Park, S.M. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry

1996-12-01

386

Electrochemical oxidation of polyethylene glycol in electroplating solution using paraffin composite copper hexacyanoferrate modified (PCCHM) anode.  

PubMed

Electrochemical oxidation of polyethylene glycol (PEG) in an acidic (pH 0.18 to 0.42) and high ionic strength electroplating solution was investigated. The electroplating solution is a major source of wastewater in the printing wiring board industry. A paraffin composite copper hexacyanoferrate modified (PCCHM) electrode was used as the anode and a bare graphite electrode was used as the cathode. The changes in PEG and total organic carbon (TOC) concentrations during the course of the reaction were monitored. The efficiency of the PCCHM anode was compared with bare graphite anode and it was found that the former showed significant electrocatalytic property for PEG and TOC removal. Chlorides present in the solution were found to contribute significantly in the overall organic removal process. Short chain organic compounds like acetic acid, oxalic acid, formic acid and ethylene glycol formed during electrolysis were identified by HPLC method. Anode surface area and applied current density were found to influence the electro-oxidation process, in which the former was found to be dominating. Investigations of the kinetics for the present electrochemical reaction suggested that the two stage first-order kinetic model provides a much better representation of the overall mechanism of the process if compared to the generalized kinetic model. PMID:15559827

Bejankiwar, Rajesh S; Basu, Abir; Cementi, Max

2004-01-01

387

Electrochemical oxidation of an azo dye in aqueous media investigation of operational parameters and kinetics.  

PubMed

In this research two types of electrochemical reactors for the treatment of simulated wastewaters containing Direct blue 71 azo dye (DB71) were used: (1) Laboratory scale undivided electrolysis cell system (450 mL volume) with one 2 cm x 2 cm platinum plate as the anode placed in the middle of the cell and two 2 cm x 8 cm steel plates (SS-304) as cathodes placed in the sides of the cell 2 cm from the central anode. (2) Pilot scale reactor (9L volume), equipped with two 3 cm x 23 cm stainless steel plates as anode and cathode, with distance of 3 cm apart. The influence of supporting electrolyte, applied voltage and pH were studied. The UV-vis spectra of samples during the electrochemical oxidation showed the rapid decolorization of the dye solution. During the process, the COD and current were measured in order to evaluate the degree of mineralization, energy consumption, current and anode efficiencies. The optimum supporting electrolyte and applied voltage were NaCl (5 g L(-1)) and 15 V. Using the lab scale reactor resulted in complete decolorization and mineralization of the dye solutions after ca. 90 and 120 min, respectively. Similar results were obtained using the pilot plant reactor under the same conditions. The good fit of the data to pseudo-first-order kinetics for COD removal at all applied voltages (except 20 V) was taken as proof of the involvement of indirect oxidation pathways in the process. PMID:19345003

Parsa, J Basiri; Rezaei, M; Soleymani, A R

2009-03-09

388

Anodic oxidation with doped diamond electrodes: a new advanced oxidation process  

Microsoft Academic Search

Boron-doped diamond anodes allow to directly produce OH radicals from water electrolysis with very high current efficiencies. This has been explained by the very high overvoltage for oxygen production and many other anodic electrode processes on diamond anodes. Additionally, the boron-doped diamond electrodes exhibit a high mechanical and chemical stability. Anodic oxidation with diamond anodes is a new advanced oxidation

Alexander Kraft; Manuela Stadelmann; Manfred Blaschke

2003-01-01

389

Nanoporous zeolite and solid-state electrochemical devices for nitrogen-oxide sensing  

NASA Astrophysics Data System (ADS)

Solid-state electrochemical gas sensing devices composed of stabilized-zirconia electrolyte have used extensively in the automobile and chemical industry. Two types of electrochemical devices, potentiometric and amperometric, were developed in this thesis for total NOx (NO + NO2) detection in harsh environments. In potentiometric devices, Pt covered with Pt containing zeolite Y (PtY) and WO3 were examined as the two electrode materials. Significant reactivity differences toward NOx between PtY and WO 3 led to the difference in non-electrochemical reactions and resulted in a electrode potential. With gases passing through a PtY filter, it was possible to remove interferences from 2000 ppm CO, 800 ppm propane, 10 ppm NH3, as well as to minimize effects of 1˜13% O2, CO2, and H2O. Total NOx concentration was measured by maintaining a temperature difference between the filter and the sensor. The sensitivity was significantly improved by connecting sensors in series. Amperometic devices were also developed to detect NOx passing through the PtY filter. By applying a low anodic potential of 80 mV, NO in the NOx equilibrated mixture can be oxidized at a Pt working electrode on the YSZ electrolyte at 500°C. The PtY can be held separate from the YSZ or coated onto the YSZ as a film. This design was demonstrated to exhibit total-NOx detection capability, a low NOx detection limit (< 1 ppm), high NOx selectivity relative to CO and oxygen, and linear dependence on NOx concentration. The non-electrochemical reactions around the triple-phase boundary were studied to understand the origin of the superior performance of WO3 on potentiometric NOx sensing. From TPD, DRIFTS, XRD, Raman, and catalytic activity measurements, the interfacial reactions between WO 3 and YSZ were found to dramatically reduce the NOx catalytic activity of YSZ. WO3 reacted with surface Y2O3 on YSZ and formed less catalytically active yttrium tungsten oxides and monoclinic ZrO2, which suppressed the non-electrochemical reactions around the triple-phase boundary. These two products also decreased the oxygen vacancy density around the triple-phase boundary, slowed down the electrochemical oxygen reduction reaction, and in turn increased the NOx signal. The surface nanostructure of electrodes was modified by wet chemical processes to change the non-electrochemical NOx reactions. A thin WO3 coating prepared from the peroxytungstate solution with well-defined triple-phase boundaries resulted in higher sensitivity and better response times than the electrode fabricated from commercial WO3 powders. The electrodeposited porous Pt layer greatly increased the surface area and led to a similar catalytic activity with PtY on NOx sensing. The modified electrodes demonstrated the importance of the surface nanostructure and interfacial species for potentiometric NOx sensing. The sensors composed of tungsten/H2O2 deposited sensing electrodes and more hydrothermal stable Pt-loaded siliceous zeolite Y (PtSY) reference electrodes have stable NO2 signal at 5-10% water in 600°C.

Yang, Jiun-Chan

390

Highly efficient and energy-saving sectional treatment of landfill leachate with a synergistic system of biochemical treatment and electrochemical oxidation on a boron-doped diamond electrode.  

PubMed

In this paper, a synergistic combination of the biochemical treatment and electrochemical oxidation (SBEO) of landfill leachate with sectional treatment on a boron-doped diamond (BDD) electrode is proposed. The first stage involves the synergistic system of biochemical treatment and electrochemical oxidation. Then, the second stage is followed by individual biochemical treatment. Comparisons among the SBEO, electrochemical oxidation, biochemical treatment and biochemical treatment with the pretreatment of electrochemical oxidation are made systematically, which show that this method is both highly efficient and energy-saving. The higher TOC removal and low energy cost on the BDD electrode can be explained by the conversion of the bio-refractory pollutants to biodegradable organics in the electrochemical oxidation process, improving the current efficiency and reducing the energy cost. The treated wastewater is degraded only with biochemical treatment in the second stage, which further improves efficiency and reduced the energy cost. PMID:20413218

Zhao, Guohua; Pang, Yaning; Liu, Lei; Gao, Junxia; Lv, Baoying

2010-04-02

391

Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste  

SciTech Connect

The different tasks that have been carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA), which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals, and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples in order to exactly predict the corrosion mechanisms; (7) Wavelet analysis of EC noise data from steel samples undergoing corrosion in an environment similar to that of the high level waste storage containers, to extract data pertaining to general, pitting and stress corrosion processes, from the overall data. The work has yielded a number of important findings, including an unequivocal demonstration of the role of chloride ion in passivity breakdown on nickel in terms of cation vacancy generation within the passive film, the first detection and characterization of individual micro fracture events in stress corrosion cracking, and the determination of kinetic parameters for the generation and annihilation of point defects in the passive film on iron. The existence of coupling between the internal crack environment and the external cathodic environment, as predicted by the coupled environment fracture model (CEFM), has also been indisputably established for the AISI 4340/NaOH system. It is evident from the studies that analysis of coupling current noise is a very sensitive tool for studying the crack tip processes in relation to the chemical, mechanical, electrochemical, and microstructural properties of the system. Experiments are currently being carried out to explore these crack tip processes by simultaneous measurement of the acoustic activity at the crack tip in an effort to validate the coupling current data. These latter data are now being used to deterministically predict the accumulation of general and localized corrosion damage on carbon in prototypical DOE liquid waste storage tanks. Computer simulation of the cathodic and anodic activity on the steel surfaces is also being carried out in an effort to simulate the actual corrosion process. Wavelet analysis of the coupling current data promises to be a useful tool to differentiate between the different corrosion mechanisms. Hence, wavelet analysis of the coupling current data from the DOE waste containers is also being carried out to extract data pertaining to general, pitting and stress corrosion processes, from the overall data which is bound to contain noise fluctuations due to any or all of the above mentioned processes.

Digby Macdonald; Brian Marx; Balaji Soundararajan; Morgan Smith

2005-07-28

392

Treatment of ink effluents from flexographic printing by lime precipitation and boron-doped diamond (BDD) electrochemical oxidation.  

PubMed

Effluent treatment from flexographic printing was investigated by precipitation/coagulation and electrochemical oxidation over boron-doped diamond electrodes. Precipitation with 3 g/L of lime led to complete removal of effluent turbidity (initial value of about 410 NTU) but only about 20% chemical oxygen demand (COD) decrease (initial value of about 1,900 mg/L). Higher lime dosages (up to 15 g/L) had no effect on separation. On the other hand, coagulation with alum in the range 0.05-1 mM failed to enhance the extent of solids separation achieved by gravity settling alone (i.e. about 60%). Preliminary electrochemical oxidation experiments in the presence of sulphuric acid as supporting electrolyte showed that treatment performance (in terms of COD removal and decrease in sample absorbance at 300 nm) increased with increasing applied current. The latter was more efficiently utilized at shorter treatment times and lower currents with efficiency reaching 30%. Following lime precipitation, the effluent was electrochemically oxidized at alkaline conditions for 360 min yielding 64% absorbance reduction and 50% COD removal (this corresponds to 60% overall COD removal for the combined process). The rather low electrochemical treatment performance may be attributed to limestone deposition and fouling of electrodes and other electrochemical reactor components as evidenced by the gradual drop in conductivity/current throughout the operation. PMID:19923752

Diamadopoulos, Evan; Barndõk, Helen; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios

2009-01-01

393

Enhanced electrochemical characteristics of lithium manganese oxide thin film cathodes for lithium-ion rechargeable microbatteries  

NASA Astrophysics Data System (ADS)

Spinel LiMn2O4 (average oxidation state of Mn = 3.5) thin film has been introduced for a promising cathode of thin film lithium-ion microbatteries because of its advantages over other cathodes. Thus, many research groups have been investigating the thin film lithium manganese oxide cathode using several different techniques but only a few of them achieved acceptable electrochemical properties required for a thin film cathode for 4 V region. However, for 3 V application the wide applications of LiMn2O 4 film as a cathode in rechargeable microbatteries have been restricted by electrochemically unfavorable facts such as capacity fade on cycling and poor rate capability at high rates. In this study, we examined the mechanisms responsible for capacity fade on cycling and rate capability of LiMn 2O4 thin film cathodes with the help of pulsed laser deposition (PLD) technique. In an attempt to address these issues, a three-part experimental procedure has been designed to look at the effect of structure and compositions of the thin film cathodes on their electrochemical characteristics. First, the effect of growth temperature of the thin film cathodes has been investigated. Next, LiMn2O4 thin film cathodes doped with aluminum, which replaces Mn3+ in the spinet structure, have been synthesized and characterized as a function of the amount of aluminum substituted. Finally, ultraviolet radiation was added to a PLD system for in situ ultraviolet-assisted PLD (UVPLD) growth of cathode films. Through the addition of ultraviolet radiation, highly reactive oxygen species are generated which alter the oxygenation conditions and dynamically alter the films properties such as crystallinity and composition. A variety of characterization techniques indicate that LiMn2O 4 thin film cathodes grown at 400˜500°C exhibit the optimized electrochemical characteristics in terms of capacity, capacity retention, and rate capability. Al-doped LiMn2O4 thin films show a more stable structure, leading to higher capacity retention with some sacrifice of discharge capacity and rate capability. Oxygen-rich spinel (LiMn2O4+delta, delta > 0) thin film cathodes produced by UVPLD result in very high capacity and better rechargeability but lower rate capability.

Kim, Won-Seok

394

Metal-mediated electrochemical oxidation of DNA-wrapped carbon nanotubes.  

PubMed

As part of the ongoing effort to describe electron transfer reactions of carbon nanotubes (CNTs), we studied the mediated electrochemical oxidation of CNTs solubilized by wrapping with a T(60) deoxyribooligonucleotide. Cyclic voltammetry revealed that the oxidation of this CNT-DNA material by electrogenerated ML(3)(3+) mediators completes a catalytic cycle that increases the oxidative current compared to that obtained by voltammetry of the mediator alone (M = Fe(III), Ru(III), or Os(III); L = 2,2'-bipyridine or 4,4'-dimethyl-2,2'-bipyridine). We observed a greater increase in current at higher nanotube concentration, slower experimental scan rate, and higher mediator redox potential (E(0)'). Using computer simulation, these observations were shown to be consistent with CNT oxidation involving the removal of multiple electrons from each CNT-DNA moiety (the T(60) oligonucleotide was chosen because it is not oxidized by any of the mediators). The data are well-described by a simulation model based on the classical catalytic mechanism (EC') with the following embellishment: three populations of CNT-DNA redox-active sites with different E(0)' and therefore different oxidation rates are employed to represent the varying redox potentials of different valence band electrons within one CNT chiral type and within the distribution of CNT types present in our sample. This modeling suggests the number of CNT-DNA sites available for oxidation increases with the E(0)' of the mediator. This result can be qualitatively interpreted in terms of CNT band theory. PMID:20565119

Campbell, Jennifer F; Napier, Mary E; Feldberg, Stephen W; Thorp, H Holden

2010-07-15

395

Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen  

NASA Astrophysics Data System (ADS)

A laboratory-scale solid oxide membrane (SOM) steam electrolyzer that can potentially use energy value in waste or any source of carbon or hydrocarbon to produce high-purity hydrogen has been fabricated and evaluated. The SOM electrolyzer comprises an oxygen-ion-conducting yttria-stabilized zirconia (YSZ) electrolyte with a Ni-YSZ cermet cathode coated on one side and liquid-metal anode on the other side. The SOM electrolyzer is operated at 1000 °C by providing a steam-rich gas feed to the Ni-YSZ cermet cathode and feeding a reductant source into the liquid-metal anode. The steam is reduced over the cathode, and oxygen ions are transported through the YSZ electrolyte and are oxidized at the molten metal electrode by the reductant feed. The advantage of SOM electrolyzer over the state-of-the-art solid oxide electrolyzer is its ability to use solid, liquid, and gaseous reductant feed in the liquid-metal anode to reduce the oxygen chemical potential and drive the reaction for hydrogen production. In this study, an electrochemical process model for a SOM electrolyzer was developed. The condition of the liquid-metal anode with reductant was simulated by bubbling humidified hydrogen (3 pct H2O) in the liquid metal, and the electrochemical performance of the SOM electrolyzer was modeled. The experimental data were curve-fitted into the model to identify the various polarization losses. It showed that the performance of the SOM electrolyzer was dominated by the ohmic resistance of the YSZ membrane. Based on the results of this study, future work is needed toward increasing the performance efficiency of the SOM electrolyzer.

Pati, Soobhankar; Yoon, Kyung Joong; Gopalan, Srikanth; Pal, Uday B.

2009-12-01

396

Modification of indium tin oxide electrodes with repeat polynucleotides: electrochemical detection of trinucleotide repeat expansion.  

PubMed

Genomic expansion of the triplet repeat sequences 5'-(CTG)n and 5'-(CGG)n leads to myotonic dystrophy and fragile X syndrome, respectively. Methods for determining the number of repeats in unprocessed nucleic acids would be useful in diagnosing diseases based on triplet repeat expansion. Electrochemical reactions based on the oxidation of guanine were expected to give larger signals per strand for expansion of repeats containing guanine. A novel PCR reaction was used to generate fragments containing 150, 230, 400, and 830 repeats of (CTG)n, which codes for myotonic dystrophy, and 130 and 600 repeats of (CGG)n, which codes for fragile X syndrome. These PCR fragments were immobilized to indium tin oxide electrodes, and oxidation of guanine in the fragments was realized using electrocatalysis by Ru(bpy)3(2+) (bpy = 2,2'-bipyridine). The catalytic currents due to oxidation of the immobilized guanines by Ru(bpy)3(3+) increased with the number of repeats and were a linear function of the repeat number when normalized to the number of strands immobilized. These results suggest a sensing strategy for repeat length based on the combination of the electrocatalytic strategy for determining the repeat length combined with existing methods for determining the number of strands. PMID:11721935

Yang, I V; Thorp, H H

2001-11-01

397

Influences of graphene oxide support on the electrochemical performances of graphene oxide-MnO2 nanocomposites  

PubMed Central

MnO2 supported on graphene oxide (GO) made from different graphite materials has been synthesized and further investigated as electrode materials for supercapacitors. The structure and morphology of MnO2-GO nanocomposites are characterized by X-ray diffraction, X-ray photoemission spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and Nitrogen adsorption-desorption. As demonstrated, the GO fabricated from commercial expanded graphite (denoted as GO(1)) possesses more functional groups and larger interplane gap compared to the GO from commercial graphite powder (denoted as GO(2)). The surface area and functionalities of GO have significant effects on the morphology and electrochemical activity of MnO2, which lead to the fact that the loading amount of MnO2 on GO(1) is much higher than that on GO(2). Elemental analysis performed via inductively coupled plasma optical emission spectroscopy confirmed higher amounts of MnO2 loading on GO(1). As the electrode of supercapacitor, MnO2-GO(1) nanocomposites show larger capacitance (307.7 F g-1) and better electrochemical activity than MnO2-GO(2) possibly due to the high loading, good uniformity, and homogeneous distribution of MnO2 on GO(1) support.

2011-01-01

398

Quantitative structure-reactivity study of electrochemical oxidation of phenolic compounds at the SnO2-based electrode.  

PubMed

In the present study, the electrochemical oxidation of 22 phenolic compounds was systemically examined at the RuO(2)-SnO(2)-Sb(2)O(5) electrode to elucidate the inherent structure-reactivity correlation. The oxidation process was monitored in situ by UV-vis spectroscopy. A variety of substituents (e.g., -CH(3), -NH(2), -Cl, -OH, -COOH, -NO(2), -CHO) were employed in order to cover various possible electronic effects. Our experimental results revealed that the relationship between the Hammett constant and rate constant for the electrochemical oxidation of phenolic compounds at the RuO(2)-SnO(2)-Sb(2)O(5) electrode was different from the results obtained at a platinum electrode. The substituted phenols with electron-withdrawing groups were electrochemically oxidized more rapidly than those with electron-donating groups. To decipher the effects of physiochemical properties on the electrochemical reactivity of phenolic compounds, 140 molecular descriptors were calculated and assessed for each phenolic compound; a quantitative structure property relationship (QSPR) model was developed. Correlations between the rate constants and quantum properties of the phenolic compounds were achieved using partial least-squares (PLS) analysis. The most crucial quantum descriptors responsible for the electrochemical reactivity of phenolic compounds were determined to be E(HOMO), chemical potential, total dipole, quadrupoles, subgraph counts, relative positive charged surface area, and pK(a). The proposed QSPR model was based on the quantum descriptors derived from the whole molecule, providing lucid explanation and effective prediction of the electrochemical reactivity of various phenolic compounds. PMID:22364571

Tian, Min; Thind, Sapanbir S; Simko, Matthew; Gao, Faming; Chen, Aicheng

2012-03-09

399

Integration of Advanced Oxidation Technologies and Biological Processes: Recent Developments, Trends, and Advances  

Microsoft Academic Search

The greatest challenge of today's wastewater treatment technology is to optimize the use of biological and chemical wastewater treatment processes. The choice of the process and\\/or integration of the processes depend strongly on the wastewater characteristics, concentrations, and the desired efficiencies. It has been observed by many investigators that the coupling of a bioreactor and advanced oxidation processes (AOPs) could

Gelareh Bankian Tabrizi; Mehrab Mehrvar

2004-01-01

400

Electrochemical oxidation of synthetic tannery wastewater in chloride-free aqueous media.  

PubMed

The electrochemical treatment of a synthetic tannery wastewater, prepared with several compounds used by finishing tanneries, was studied in chloride-free media. Boron-doped diamond (Si/BDD), antimony-doped tin dioxide (Ti/SnO(2)-Sb), and iridium-antimony-doped tin dioxide (Ti/SnO(2)-Sb-Ir) were evaluated as anode. The influence of pH and current density on the treatment was assessed by means of the parameters used to measure the level of organic contaminants in the wastewater; i.e., total phenols, chemical oxygen demand (COD), total organic carbon (TOC), and absorbance. Results showed that faster decrease in these parameters occurred when the Si/BDD anode was used. Good results were obtained with the Ti/SnO(2)-Sb anode, but its complete deactivation was reached after 4h of electrolysis at 25 mA cm(-2), indicating that the service life of this electrode is short. The Ti/SnO(2)-Sb-Ir anode is chemically and electrochemically more stable than the Ti/SnO(2)-Sb anode, but it is not suitable for the electrochemical treatment under the studied conditions. No significant changes were observed for electrolyses performed at different pH conditions with Si/BDD, and this electrode led to almost complete mineralization after 4h of electrolysis at 100 mA cm(-2). The increase in current density resulted in faster wastewater oxidation, with lower current efficiency and higher energy consumption. Si/BBD proved to be the best electrodic material for the direct electrooxidation of tannery wastewaters. PMID:20452722

Costa, Carla Regina; Montilla, Francisco; Morallón, Emilia; Olivi, Paulo

2010-04-18

401

Mediated electrochemical oxidation treatment for Rocky Flats combustible low-level mixed waste. Final report, FY 1993 and 1994  

SciTech Connect

Mediated Electrochemical Oxidation (MEO) is an aqueous process which destroys hazardous organics by oxidizing a mediator at the anode of an electrochemical cell; the mediator in turn oxidizes the organics within the bulk of the electrolyte. With this process organics can be nearly completely destroyed, that is, the carbon and hydrogen present in the hydrocarbon are almost entirely mineralized to carbon dioxide and water. The MEO process is also capable of dissolving radioactive materials, including difficult-to-dissolve compounds such as plutonium oxide. Hence, this process can treat mixed wastes, by destroying the hazardous organic components of the waste, and dissolving the radioactive components. The radioactive material can be recovered if desired, or disposed of as non-mixed radioactive waste. The process is inherently safe, since the hazardous and radioactive materials are completely contained in the aqueous phase, and the system operates at low temperatures (below 80{degree}C) and at ambient pressures.

Chiba, Z.; Lewis, P.R.; Murguia, L.C.

1994-09-01

402

The kinetics and electrochemical rate-determining step of aqueous pyrite oxidation  

NASA Astrophysics Data System (ADS)

Rate data available in the literature have been compiled for the reaction of pyrite with dissolved oxygen (DO) to produce a rate law that is applicable over four orders of magnitude in DO concentration over the pH range 2-10. The valid rate law is ? where r is the rate of pyrite destruction in units of mol m -2 s -1. A series of batch and mixed flow reactor experiments were performed to determine the effect of SO 42-, Cl -, ionic strength, and dissolved oxygen on the rate of reaction of pyrite with ferric iron. Of these, only dissolved oxygen was found to have any appreciable effect. Experimental results of the present study were combined with kinetic data reported in the literature to formulate rate laws that are applicable over a six order of magnitude range in Fe 3+ and Fe 2+ concentration for the pH range ~0.5-3.0. In N 2-purged solution, the rate law is ? and when dissolved oxygen is present, ? where r is the rate of pyrite destruction in mol m -2 s -1. Experiments were also performed in which a single pyrite sample was repeatedly reacted with ferric iron solutions of the same composition and identical surface area to mass of solution ratio ( A/ M). For each subsequent experiment, the rate of reaction slowed and the original behavior of the pyrite could not be reestablished by washing the pyrite with concentrated HNO 3 or EDTA. This behavior was interpreted as representative of a change in the electrochemical properties of the solid pyrite. Pretreating pyrite samples with aqueous solutions of ferrous iron and EDTA did not change the reaction rate with ferric iron; however, pretreatment with hydroxylamine hydrochloride lowered the rate significantly. The data presented are best modeled by a nonsite-specific Freundlich multilayer isotherm. Good correlation was found between Eh and rate for the aqueous oxidation of pyrite with DO and ferric iron. Because the fractional orders of reaction are difficult to explain with a purely molecular-based mechanism, a cathodic-anodic electrochemical mechanism is favored to explain the transfer of the electron from pyrite to the aqueous oxidant. Mechanistically, the results of this study suggest a nonsite specific interaction between dissolved oxidants and the pyrite surface. Rate correlates strongly with Eh ( Fe 3+/Fe 2+ ratio or DO concentration) and is consistent with an electrochemical mechanism where anodic and cathodic reactions occur at different places on the pyrite surface.

Williamson, Mark A.; Rimstidt, J. Donald

1994-12-01

403

Single pot synthesis of polyaniline protected silver nanoparticles by interfacial polymerization and study its application on electrochemical oxidation of hydrazine  

Microsoft Academic Search

PANI–Ag nanocomposites were successfully synthesized by interfacial polymerization processes using aniline dimer (4-aminophenyldiphenylamine, APDA) as starting material in chloroform in contact with an aqueous solution of silver nitrate at different molar ratios. Synthesized PANI–Ag nanocomposites were characterized through various instrumental techniques. The electrocatalytic behavior of the nanocomposite was tested for the electrochemical oxidation of hydrazine.

P. Paulraj; N. Janaki; S. Sandhya; K. Pandian

2011-01-01

404

Facilely prepared polypyrrole-reduced graphite oxide core-shell microspheres with high dispersibility for electrochemical detection of dopamine.  

PubMed

Polypyrrole-reduced graphite oxide core-shell microspheres with high dispersibility were facilely fabricated and were demonstrated to be excellently sensitive for electrochemical detection of nanomolar concentrations of dopamine in the presence of a large excess of uric acid and ascorbic acid. PMID:23527381

Qian, Tao; Wu, Shishan; Shen, Jian

2013-05-21

405

Relation between reactivity and electrochemical oxidation reduction potentials of organomercury compounds. I. Symmetrization of substituted ethyl. cap alpha. -bromomercuriophenylacetates  

Microsoft Academic Search

An approximate correlation equation relating the logarithms of the reaction rate constants for the symmetrization of para-substituted ethyl ..cap alpha..-bromomercuriophenylacetates simultaneously with the electrochemical reduction and oxidation potentials of these compounds was obtained on the basis of molecular orbital perturbation theory and was confirmed by experimental data. This equation makes it possible to assess the degree of concertedness of the

K. P. Butin; R. D. Rakhimov; O. A. Reutov

1987-01-01

406

In vivo and In vitro Differences in the Charge-injection and Electrochemical Properties of Iridium Oxide Electrodes  

Microsoft Academic Search

The electrochemical response of activated iridium oxide (AIROF) electrodes implanted acutely in the subretinal space of the rabbit is compared with in vitro measurements in model electrolytes. Voltage transients during current pulsing, cyclic voltammetry, impedance spectroscopy and open-circuit potential measurements were compared. Subretinal charge injection by constant current pulsing required significantly greater driving voltages due to both higher access resistances

Stuart F. Cogan

2006-01-01

407

Measurement of oxide barrier-film thickness of Al alloy by electrochemical impedance spectroscopy at the nanometre scale  

NASA Astrophysics Data System (ADS)

In this study, the effect of the annealing treatment on electrochemical behaviour and the oxide barrier-film thickness of anodized aluminium-magnesium (Al-Mg) alloy was investigated. Electrochemical parameters such as the polarization resistance (RP), solution resistance (RSol), alternating current impedance (Z), and the double layer capacitance (CdL) of the anodized Al-Mg alloy were determined in sulphuric acid solutions ranged from 0-10% H2SO4 by electrochemical impedance spectroscopy (EIS) methods. Then, the oxide film thickness of the anodized Al-Mg alloy was measured from the obtained electrochemical parameters as a function of the sulphuric acid concentration (0-10% H2SO4), in the as received sample and annealed sample conditions. The optimum thickness of the oxide film was detected for the as received samples (4.2nm) and for the annealed samples (0.63nm) in sulphuric acid concentrations of 4% and 2% H2SO4, respectively. The reason behind the oxide film thickness of the as received samples is greater than the one for the annealed samples, because the former samples are thermodynamically unstable (more chemically active) as compared to the annealed samples.

Habib, K.

2008-08-01

408

Electrochemical oxidation of 3-methylpyridine at a boron-doped diamond electrode: application to electroorganic synthesis and wastewater treatment  

Microsoft Academic Search

The electrochemical oxidation of 3-methylpyridine (3-MP) at synthetic boron-doped diamond (BDD) thin film electrode has been studied in acid media by cyclic voltammetry and bulk electrolysis. The results have shown that in the potential region of water stability there can occur direct electron transfer reactions on BDD surface that result in electrode fouling due to the formation of a polymeric

J. Iniesta; P. A. Michaud; M. Panizza; Ch. Comninellis

2001-01-01

409

Analysis of the solid state transport involved in the electrochemical vapor deposition of binary and ternary oxides  

SciTech Connect

In the electrochemical vapor deposition (EVD) process, gaseous cation precursors are passed over one side of a porous substrate, and oxygen is passed on the other side of the substrate. The gases diffuse and react within the porous substrate, and the pores get filled with the desired solid oxide. Subsequent solid state electrochemical transport through the solid oxide in the pores continues the reaction and the film grows over the porous substrate. In an ideal EVD process the deposition conditions are selected in such a way that the solid state electrochemical transport becomes the slowest step and it controls the deposition process. Therefore, the success in depositing an oxide by this process will depend on its solid state transport properties. In this paper, the overall equation that describes this solid state electrochemical transport has been derived and the way the various transport properties influence the deposit structure and growth is discussed. Using generalized equations, it has been shown that the EVD growth rate measurements can also be used to determine the defect structure and solid state transport properties of the rate controlling minority species in the oxide.

Pal, U.B.; Chou, K.C. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering)

1991-08-01

410

Comparison of different advanced oxidation processes for phenol degradation  

Microsoft Academic Search

Advanced Oxidation Processes (O3, O3\\/H2O2, UV, UV\\/O3, UV\\/H2O2, O3\\/UV\\/H2O2, Fe2+\\/H2O2 and photocatalysis) for degradation of phenol in aqueous solution have been studied in earlier works. In this paper, a comparison of these techniques is undertaken: pH influence, kinetic constants, stoichiometric coefficient and optimum oxidant\\/pollutant ratio. Of the tested processes, Fenton reagent was found to the fastest one for phenol degradation.

Santiago Esplugas; Jaime Giménez; Sandra Contreras; Esther Pascual; Miguel Rodr??guez

2002-01-01

411

Electrochemical and structural characterizations of electrodeposited iridium oxide thin-film electrodes applied to neurostimulating electrical signal  

Microsoft Academic Search

Thin-film technology takes more and more importance in the development of biomedical devices dedicated to functional neurostimulation. Our research about the design of implantable neurostimulating electrode is oriented toward thin-film cuff electrodes based on PTFE substrate covered by a gold\\/iridium oxide film. A gold-sputtered film serves as adhesion layer and current collector whereas iridium oxide acts as an electrochemical actuator.

S. C Mailley; M Hyland; P Mailley; J. M McLaughlin; E. T McAdams

2002-01-01

412

Scanning electrochemical microscopy of hydrogen electro-oxidation. Rate constant measurements and carbon monoxide poisoning on platinum  

Microsoft Academic Search

We describe an application of the scanning electrochemical microscope that uses tip–sample feedback to characterize the electro-oxidation of hydrogen on a polycrystalline platinum electrode in sulfuric acid solutions in the presence and absence of adsorbed carbon monoxide. The hydrogen oxidation reaction is probed by reducing protons at a diffusion-limited rate at the microscope's tip electrode while it is positioned near

Krishnakumar Jambunathan; Biren C. Shah; John L. Hudson; Andrew C. Hillier

2001-01-01

413

Electrochemical behavior of a platinum anode for reduction of uranium oxide in a LiCl molten salt  

Microsoft Academic Search

The electrochemical behavior of a platinum anode has been investigated during the electrolysis of uranium oxide in a LiCl molten salt. Pt is oxidized to Pt2+ at 2.6V (vs. Li–Pb reference electrode) in the absence of O2? ion. The platinum dissolution takes place at a more anodic potential with an increase of O2? ion. Although the main anodic process in

Sang Mun Jeong; Ho-Sup Shin; Soo-Haeng Cho; Jin-Mok Hur; Han Soo Lee

2009-01-01

414

Anodic, cathodic and combined treatments for the electrochemical oxidation of an effluent from the flame retardant industry  

Microsoft Academic Search

The electrochemical oxidation of an effluent from the manufacture of phosphorus based flame retardants was studied. To reach\\u000a a residual concentration of reduced phosphorus lower than 10 mg L?1, in compliance with Italian law for industrial wastewater disposal, anodic oxidation using a boron-doped diamond (BDD) anode\\u000a and electro-Fenton (EF) treatment were tested. The effects of some factors are optimised and a comparison

Daniele Montanaro; Elisabetta Petrucci; Carlo Merli

2008-01-01

415

Electrochemical performance of LBO-coated spinel lithium manganese oxide as cathode material for Li-ion battery  

Microsoft Academic Search

Surface treatment of the lithium manganese oxide cathode material coated by lithium borate glass (Li2O–2B2O3) with improved electrochemical cyclability and structural stability was conducted in this study. The lithium manganese oxide powder doped with various weight percentages of LBO glass was calcined to form a fine powder with single spinel phase, exhibiting different particle size, size distribution and morphology. The

Hung-Wei Chan; Jenq-Gong Duh; Shyang-Roeng Sheen

2004-01-01

416

Electrochemical oxidation and determination of ceftriaxone on a glassy carbon and carbon-nanotube-modified glassy carbon electrodes  

Microsoft Academic Search

The electrochemical behavior of ceftriaxone was investigated on a carbon-nanotube-modified glassy carbon (GC-CNT) electrode\\u000a in a phosphate buffer solution, pH?=?7.40, and the results were compared with those obtained using the unmodified one [glassy\\u000a carbon (GC) electrode]. During oxidation of ceftriaxone, an irreversible anodic peak appeared, using both modified and unmodified\\u000a electrodes. Cyclic voltammetric studies indicated that the oxidation process is

S. Majdi; A. Jabbari; H. Heli; H. Yadegari; A. A. Moosavi-Movahedi; S. Haghgoo

2009-01-01

417

Electrochemical oxidation of esters of ethane-1,1,2,2-tetracarboxylic acid in the presence of electron carrier catalysts  

Microsoft Academic Search

1.Electrochemical oxidation of esters of ethane-1,1,2,2-tetracarboxylic acid in the presence of hydrohalic acid salts in acetonitrile leads to esters of ethylenetetracarboxylic acid; in alcohols not only an oxidative dehydrogenation takes place, but also esters of 1-alkoxyethane-1,1,2,2-tetracarboxylic acid are formed.2.When the reaction is carried out in methanol, the yield of the ester of ethylenetetracarboxylic acid and the ester of 1-methoxyethane-1,1,2,2-tetracarboxylic acid

M. N. Élinson; S. K. Fedukovich; G. I. Nikishin

1988-01-01

418

Comparison of TiN, ZrN and CrN hard nitride coatings: Electrochemical and thermal oxidation  

Microsoft Academic Search

Although TiN has hitherto been the most extensively investigated hard coating, other binary and ternary nitrides are the subject of ever-increasing interest. In this work the behaviour of TiN, ZrN and CrN coatings is compared, concentrating on the mechanism of their oxidation. The sequence of the processes included in the electrochemical and thermal oxidation was followed by X-ray photoelectron spectroscopy

I. Milošev; H.-H. Strehblow; B. Navinsek

1997-01-01

419

Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors.  

PubMed

Fractional exhaled nitric oxide (F(E)NO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring F(E)NO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for the detection of NO at the sub-part-per-billion by volume (ppbv, 110(-9)) level. The characteristics and diagnostic performance of the sensor were assessed. A detection limit of 0.5 ppbv was demonstrated with a relatively simple design. The QCL-based sensor was compared with two market sensors, a chemiluminescent analyzer (NOA 280, Sievers) and a portable hand-held electrochemical analyzer (MINO, Aerocrine AB, Sweden). F(E)NO from 20 children diagnosed with asthma and treated with inhaled corticosteroids were measured. Data were found to be clinically acceptable within 1.1 ppbv between the QCL-based sensor and chemiluminescent sensor and within 1.7 ppbv when compared to the electrochemical sensor. The QCL-based sensor was tested on healthy subjects at various expiratory flow rates for both online and offline sampling procedures. The extended NO parameters, i.e. the alveolar region, airway wall, diffusing capacity, and flux were calculated and showed a good agreement with the previously reported values. PMID:22352669

Mandon, Julien; Högman, Marieann; Merkus, Peter J F M; van Amsterdam, Jan; Harren, Frans J M; Cristescu, Simona M

2012-01-01

420

Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors  

NASA Astrophysics Data System (ADS)

Fractional exhaled nitric oxide (FENO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring FENO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for the detection of NO at the sub-part-per-billion by volume (ppbv, 1?10-9) level. The characteristics and diagnostic performance of the sensor were assessed. A detection limit of 0.5 ppbv was demonstrated with a relatively simple design. The QCL-based sensor was compared with two market sensors, a chemiluminescent analyzer (NOA 280, Sievers) and a portable hand-held electrochemical analyzer (MINO®, Aerocrine AB, Sweden). FENO from 20 children diagnosed with asthma and treated with inhaled corticosteroids were measured. Data were found to be clinically acceptable within 1.1 ppbv between the QCL-based sensor and chemiluminescent sensor and within 1.7 ppbv when compared to the electrochemical sensor. The QCL-based sensor was tested on healthy subjects at various expiratory flow rates for both online and offline sampling procedures. The extended NO parameters, i.e. the alveolar region, airway wall, diffusing capacity, and flux were calculated and showed a good agreement with the previously reported values.

Mandon, Julien; Högman, Marieann; Merkus, Peter J. F. M.; van Amsterdam, Jan; Harren, Frans J. M.; Cristescu, Simona M.

2012-01-01

421

Behavior of molybdenum nitrides as materials for electrochemical capacitors: Comparison with ruthenium oxide  

SciTech Connect

Ruthenium oxide (RuO{sub 2}), formed as a thin film on a Ru or Ti metal substrate, exhibits a large specific (cm{sup {minus}2}) and almost constant, electrochemical capacitance over a 1.35 V range in aqueous H{sub 2}SO{sub 4}. This behavior has led to its investigation and use as a material for fabrication of supercapacitor devices. However, its cost has encouraged search for other materials exhibiting similar behavior. Work reported in the present paper evaluates two nitrides of Mo, Mo{sub 2}N and MoN, as substitutes for RuO{sub 2}. It is shown that very similar capacitance behavior to that of RuO{sub 2} films arises, e.g., in cyclic voltammetry and dc charging curves; in the former, almost mirror-image anodic and cathodic current-response profiles, characteristic of a capacitor, arise. However, the nitride materials have a substantially smaller voltage operating range of only some 0.7 V due to electrochemical decomposition above ca. 0.7 V vs. RHE. This limits their usefulness as a substitute for RuO{sub 2}. Of interest is that the nitride films exhibit potential-decay and potential-recovery on open circuit after respective charge and forced discharge. The decay and recovery processes are logarithmic in time, indicating the role of internal faradaic charge redistribution processes.

Liu, T.C.; Pell, W.G.; Conway, B.E. [Univ. of Ottawa, Ontario (Canada). Dept. of Chemistry; Roberson, S.L. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering

1998-06-01

422

Electrochemical incineration of dimethyl phthalate by anodic oxidation with boron-doped diamond electrode.  

PubMed

The anodic oxidation of aqueous solutions containing dimethyl phthalate (DMP) up to 125 mg/L with sodium sulfate (Na2SO4) as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond (BDD) as anode. Electrolyses were carried out at constant current density (1.5-4.5 mA/cm2). Complete mineralization was always achieved owing to the great concentration of hydroxyl radical (*OH) generated at the BDD surface. The effects of pH, apparent current density and initial DMP concentration on the degradation rate of DMP, the specific charge required for its total mineralization and mineralization current efficiency were investigated systematically. The mineralization rate of DMP was found to be pH-independent and to increase with increasing applied current density. Results indicated that this electrochemical process was subjected, at least partially, to the mass transfer of organics onto the BDD surface. Kinetic analysis of the temporal change of DMP concentration during electrolysis determined by High Performance Liquid Chromatography (HPLC) revealed that DMP decay under all tested conditions followed a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and a general pathway for the electrochemical incineration of DMP on BDD was proposed. PMID:19999984

Hou, Yining; Qu, Jiuhui; Zhao, Xu; Liu, Huijuan

2009-01-01

423

Synthesis, X-ray structure and electrochemical oxidation of palladium(II) complexes of ferrocenyldiphenylphosphine.  

PubMed

Four new complexes, [PdX(?(2)-2-C(6)R(4)PPh(2))(PPh(2)Fc)] [X = Br, R = H (1), R = F (2); X = I, R = H (3), R = F (4)], containing ferrocenyldiphenylphosphine (PPh(2)Fc) have been prepared and fully characterised. The X-ray structures of complexes trans-1, cis-2 and cis-4, and that of a decomposition product of 4, [Pd(?(2)-2-C(6)F(4)PPh(2))(?-I)(?-2-C(6)F(4)PPh(2))PdI(PPh(2)Fc)] (5), have been determined. These complexes show a distorted square planar geometry about the metal atom, the bite angles of the chelate ligands being about 69°, as expected. The cis/trans ratio of 1-4 in solution is strongly dependent on solvent. The new complexes and the uncoordinated PPh(2)Fc ligand were electrochemically characterised by cyclic and rotating disk voltammetry, UV-visible spectroelectrochemistry, and bulk electrolysis in dichloromethane and acetonitrile. In both cases, oxidation occurs at both the ferrocene and phosphine centres, but the complexes oxidise at more positive potentials than uncoordinated PPh(2)Fc; subsequently, the metal-phosphorus bond is cleaved, leading to free PPh(2)Fc(+), which undergoes further chemical and electrochemical reactions. PMID:20730243

Bennett, Martin A; Bhargava, Suresh K; Bond, Alan M; Burgar, Iko M; Guo, Si-Xuan; Kar, Gopa; Privér, Steven H; Wagler, Jörg; Willis, Anthony C; Torriero, Angel A J

2010-08-23

424

Enhanced electrochemical oxidation of phenol by introducing ferric ions and UV radiation.  

PubMed

The mineralization of phenol in aerated electrochemical oxidation has been investigated. The results show that a cathodic Fenton process can occur when the Ti-0.3Mo-0.8Ni alloy material is used as cathode in solution containing ferric or ferrous ions; moreover, the reinforcement of cathodic Fenton process on the total organic carbon (TOC) removal rate of phenol is quite distinct. Among the metallic ions investigated, the ferric ion is the best catalyst for the electrochemical mineralization of phenol at initial pH 2.0, and the optimal concentration range is from 50 to 200 mg/L. The favorable pH range and supporting electrolyte (Na2SO4) concentration for mineralization of phenol in solution containing ferrous ions are 1.8-2.3 and below 0.10 mol/L, respectively. UV radiation can improve the TOC removal rate of phenol, but the enhanced effect varies in different solutions. In the solution containing ferric ions, an equal sum or synergetic effect can be observed. The optimal effect of electrolysis system under UV radiation is achieved in the solution containing 50 mg/L Fe3+ with a final removal percentage of 81.3%. PMID:19202880

Mao, Xuhui; Wei, Lin; Hong, Song; Zhu, Hua; Lin, An; Gan, Fuxing

2008-01-01

425

Mechanism for resistive switching in an oxide-based electrochemical metallization memory  

NASA Astrophysics Data System (ADS)

A comparison of the asymmetric OFF-state current-voltage characteristics between Cu/ZnO/Pt and Cu/ZnO/Al-doped ZnO (AZO) electrochemical metallization memory (ECM) cells demonstrates that the Cu filament rupture and rejuvenation occur at the ZnO/Pt (or AZO) interface, i.e., the cathodic interface. Therefore, the filament is most likely to have a conical shape, with wider and narrower diameters formed at the anodic and cathodic interfaces, respectively. It is inferred that the filament growth starts at the anode surface and stops at the cathode surface. Our results indicate that oxide-based ECM cells strongly differ from sulfide- and selenide-based ones in the resistive switching mechanism.

Peng, Shanshan; Zhuge, Fei; Chen, Xinxin; Zhu, Xiaojian; Hu, Benlin; Pan, Liang; Chen, Bin; Li, Run-Wei

2012-02-01

426

?-Fe2O3 nanotubes-reduced graphene oxide composites as synergistic electrochemical capacitor materials.  

PubMed

We present a facile approach for the fabrication of a nanocomposite comprising ?-Fe(2)O(3) nanotubes (NTs) anchored on reduced graphene oxide (rGO) for electrochemical capacitors (ECs). The hollow tubular structure of the ?-Fe(2)O(3) NTs presents a high surface area for reaction, while the incorporation of rGO provides an efficient two-dimensional conductive pathway to allow fast, reversible redox reaction. As a result, the nanocomposite materials exhibit a specific capacitance which is remarkably higher (~7 times) than ?-Fe(2)O(3) NTs alone. In addition, the nanocomposites show excellent cycling life and large negative potential window. These findings suggest that such nanocomposites are a promising candidate as negative electrodes in asymmetrical capacitors with neutral electrolytes. PMID:22441701

Lee, K K; Deng, S; Fan, H M; Mhaisalkar, S; Tan, H R; Tok, E S; Loh, K P; Chin, W S; Sow, C H

2012-03-23

427

Electrochemical regeneration of sodium hypochlorite in the absorption-oxidation method of desorbing waste gases  

SciTech Connect

The electrochemical synthesis of sodium hypochlorite from a solution with a reduced concentration of sodium chloride is efficiently carried out with the use of ruthenium oxide-titanium anodes (ROTA). In this context they investigated the electrolysis of a solution of sodium chloride with concentrations equal to 20 and 50 kg/m/sup 3/ in a single cell flow-type electrolyzer with an ROTA and, for comparison, with a graphite anode under laboratory conditions. A flow-type electrolyzer was selected in view of the fact that it most closely satisfies the purposes of gas purification. The current efficiency with respect to sodium hypochlorite was almost two times higher, and the specific consumption of electrical energy was 1.6-1.8 times lower in the case of the ROTA than in the case of the graphite electrode. The yield of sodium chlorate remained on the same level in both cases.

Znamenskii, Yu.D.; Perchugov, G.Ya.

1988-07-10

428

Electrochemical oxidation of methanol on Pt nanoparticles composited MnO 2 nanowire arrayed electrode  

NASA Astrophysics Data System (ADS)

By use of the membrane-template synthesis route, MnO 2 nanowire arrayed electrodes are successfully synthesized by means of the anodic deposition technique. The Pt nanoparticles composited MnO 2 nanowire arrayed electrodes (PME) are obtained through depositing Pt on MnO 2 nanowire arrayed electrode by cathode deposition technique. For comparison of electrochemical performance, Pt nanowire arrayed electrodes which have the same amount of Pt with PME are also prepared. The electro-oxidation of methanol on PME and Pt nanowire arrayed electrodes is investigated at room temperature by cyclic voltammetry, which show that about 110 mV decreased overpotential and 2.1-fold enhanced votammetric current are achieved on PME. The chronoamperometry result demonstrates that the resistance to carbon monoxide for PME is improved.

Zhao, Guang-Yu; Li, Hu-Lin

2008-03-01

429

Giant cationic polyelectrolytes generated via electrochemical oxidation of single-walled carbon nanotubes.  

PubMed

Previously, reduced single-walled carbon nanotube anions have been used for effective processing and functionalization. Here we report individually separate and distinct (that is, discrete) single-walled carbon nanotube cations, directly generated from a pure anode using a non-aqueous electrochemical technique. Cyclic voltammetry provides evidence for the reversibility of this nanoion electrochemisty, and can be related to the complex electronic density of states of the single-walled carbon nanotubes. Fixed potentiostatic oxidation allows spontaneous dissolution of nanotube cations ('nanotubium'); Raman spectroscopy and transmission electron microscopy show that sequential fractions are purified, separating amorphous carbon and short, defective single-walled carbon nanotubes, initially. The preparation of nanotubium, in principle, enables a new family of nucleophilic grafting reactions for single-walled carbon nanotubes, exploited here, to assemble nanotubes on amine-modified Si surfaces. Other nanoparticle polyelectrolyte cations may be anticipated. PMID:23764646

Hodge, Stephen A; Bayazit, Mustafa K; Tay, Hui Huang; Shaffer, Milo S P

2013-01-01

430

Impurities within carbon nanotubes govern the electrochemical oxidation of substituted hydrazines.  

PubMed

Electrochemistry and electrocatalysis on carbon nanomaterials is at the forefront of research. The presence of carbonaceous and metallic impurities within carbon nanotubes (CNTs) is a persistent problem. Here we show that the electrochemistry of the entire group of hydrazine compounds is governed by impurities within single-walled, double-walled and few-walled CNTs. The oxidation of organic substituted hydrazines at CNTs is driven by nanographitic impurities, in contrast to unsubstituted hydrazine, for which the electrochemistry is driven by metallic impurities within CNTs. This finding is unexpected, as one would assume that a whole group of compounds would be susceptible to "electrocatalysis" by only one type of impurity. This discovery should be taken into account when predicting the susceptibility of whole groups of compounds to electrocatalysis by metallic or nanographitic impurities. Our findings have strong implications on the electrochemical sensing of hydrazines and on the use of hydrazines as fuels for nanomotors. PMID:21556440

Stuart, Emma J E; Pumera, Martin

2011-05-10

431

Advanced Oxidation Processes for Wastewater Treatment: State of the Art  

Microsoft Academic Search

The protection and conservation of natural resources is one of the main priorities of modern society. Water is perhaps our\\u000a most valuable resource, and thus should be recycled. Many of the current recycling techniques for polluted water only concentrate\\u000a the pollutant without degrading it or eliminating it. In this sense, advanced oxidation processes are possibly one of the\\u000a most effective

J. M. Poyatos; M. M. Muñio; M. C. Almecija; J. C. Torres; E. Hontoria; F. Osorio

2010-01-01

432

Homogenous and Heterogenous Advanced Oxidation of Two Commercial Reactive Dyes  

Microsoft Academic Search

Two commercial reactive dyes, the azo dye Reactive Black 5 and the copper phythalocyanine dye Reactive Blue 21, have been treated at a concentration of 75 mg l-1 by titanium dioxide mediated photocatalytic (TiO2\\/UV), dark and UV-light assisted Fenton (Fe2+\\/H2O2) and Fenton-like (Fe3+\\/H2O2) processes in acidic medium. For the treatment of Reactive Black 5, all investigated advanced oxidation processes were

I. A. Balcioglu; I. Arslan; M. T. Sacan

2001-01-01

433

Oxidation of alloys targeted for advanced steam turbines  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines.

Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Ziomek-Moroz, M.; Alman, D.E.

2006-03-12

434

High Dielectric Constant Oxides for Advanced Micro-Electronic Applications.  

National Technical Information Service (NTIS)

A series of mixed oxide compounds have been manufactured and studied with a view to assessing their suitability for applications in advanced microelectronics: ZrO2, Ta2O5, LaAlO3, Sm2O3, Pr2O3, Nd2O3, TiO2, Ti(x)Si(1- x)O2. Although each material has dist...

R. A. Devine

2006-01-01

435

Facile electrochemical oxidation of polyaromatic hydrocarbons to surface-confined redox-active quinone species on a multiwalled carbon nanotube surface.  

PubMed

Polyaromatic hydrocarbon (PAH) oxidation: PAHs, which are considered major environmental pollutants, are carcinogenic, and cannot be electrochemically oxidized on conventional electrodes (gold, platinum, and glassy carbon), can be electrochemically oxidized on multiwalled carbon nanotube surfaces at a potential of 1?V versus Ag/AgCl at pH?7. This results in the formation of stable surface-confined quinone systems (see scheme; AN = anthracene; AQ = anthraquinone). PMID:23296450

Barathi, Palani; Kumar, Annamalai Senthil

2013-01-07

436

An electrochemical impedance study of the oxygen evolution reaction at hydrous iron oxide in base.  

PubMed

The oxygen evolution reaction at multi-cycled iron oxy-hydroxide films in aqueous alkaline solution is discussed. Steady-state Tafel plot analysis and electrochemical impedance spectroscopy have been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slopes of ca. 60 mV dec(-1) and 40 mV dec(-1) are found at low overpotentials depending on the oxide growth conditions, with an apparent Tafel slope of ca. 120 mV dec(-1) at high overpotentials. Reaction orders of ca. 0.5 and 1.0 are observed at low and high overpotentials, again depending on the oxide growth conditions. A mechanistic scheme involving the active participation of octahedrally coordinated anionic iron oxyhydroxide surfaquo complexes, which form the porous hydrous layer, is proposed. The latter structure contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution. This work brings together current research in heterogeneous electrocatalysis and homogeneous molecular catalysis for water oxidation. PMID:23348122

Doyle, Richard L; Lyons, Michael E G

2013-04-14

437

Electrochemical oxide nanotube formation on the Ti-35Ta-xHf alloys for dental materials.  

PubMed

In this study, we investigated the electrochemical oxide nanotube formation on the Ti-35Ta-xHf alloys for dental materials. The Ti-35Ta-xHf alloys contained from 3 wt.% to 15 wt.% Hf were manufactured by arc melting furnace. The nanotube oxide layers were formed on Ti-35Ta-xHf alloy by anodic oxidation method in 1 M H3PO4 electrolytes containing 0.5 wt.% NaF and 0.8 wt.% NaF at room temperature. The surface characteristics of Ti-35Ta-xHf alloy and nanotube morphology were determined by FE-SEM, STEM, and XRD. The nano-porous surface of Ti-35Ta-xHf alloys showed in 0.5 wt% NaF solution and nanotubular surface showed in 0.8 wt% NaF solution, respectively. The highly ordered nanotube layer without regular knots was formed on the Ti-35Ta-15Hf alloy in the 0.5 wt% NaF solution compared to on Ti-35Ta-3Hf and Ti-35Ta-7Hf alloys in 0.8 wt% NaF solution. Also, the nanotube length of Ti-35Ta-xHf alloys increased as Hf content increased. PMID:22103212

Moon, Byung-Hak; Jeong, Yong-Hoon; Choe, Han-Cheol

2011-08-01

438

An electrochemical study of the surface oxidation of arsenopyrite in alkaline media  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of arsenopyrite (FeAsS) electrodes in alkaline cyanide solutions has been investigated in an attempt to gain a better understanding of its dissolution chemistry. Surface oxidation reactions of arsenopyrite have been studied using cyclic voltammetry for pH values between 8.1 and 12.0 and for cyanide concentration from 10-4 to 10-2 M. Anodic oxidation of FeAsS appears to be sensitive to both pH and cyanide, as indicated by a characteristic peak at 0.30 V vs SHE for pH 11.3 and 10-2 M CN-. The anodic process corresponding to the main peak is described by the reaction: FeAsS + 9H2O = FeOOH + H2AsO3 - + SO4 2- + 15H+ + 12 e - The oxidation of the H2AsO3 -to HAsO4 2- is detected by a second wave at higher potentials under quiescent conditions. At high pH, the main peak is insensitive to the presence of cyanide, whereas at low-alkalinity this peak is sensitive to cyanide.

Sanchez, Victor; Hiskey, J. Brent

1988-12-01

439

Effect of preadsorbed sulfur on the electrochemical reduction of nitric oxide  

SciTech Connect

The effect of adsorbed sulfur on platinum black/Teflon gas diffusion electrodes has been studied. The controlled deposition and characterization of intermediate coverages of sulfur (fractional sulfur coverages, {Theta}, between 0 and 1.0, based on the total number of Pt surface sites) was first studied, followed by an investigation of the effects of this preadsorbed sulfur on the electrogenerative (i.e. galvanic) reduction of pure and dilute (3%) NO feeds. These effects are discussed in terms of possible applications for electrogenerative NO reduction, especially hydroxylamine production and flue gas scrubbing applications. Sulfur was deposited through electrochemical reduction of sulfur dioxide which had bene previously adsorbed from SO{sub 2}-containing aqueous sulfuric acid solutions. The sulfur layers deposited in this manner were electrochemically characterized using linear sweep and cyclic voltammetry. Sulfur/hydrogen coadsorption coverage plots constructed from coulometric measurements were studied and yielded evidence that a sulfur bilayer is formed on the electrode. In the presence of adsorbed sulfur (0.2 < {Theta} < 1.0) the current generated by the nitric oxide-hydrogen electrogenerative cell was diminished. This effect was more pronounced with pure NO feeds. The decreased cell current involved not only diminished NO conversion, but also a change in product distribution brought about by adsorbed sulfur. At low sulfur coverages and low cell potentials ammonia is the predominant product, but at higher sulfur coverages selectivity shifts to favor hydroxylamine production. Nitrous oxide is formed only at high cell potentials at all sulfur coverages, and nitrogen formation is allowed at lower sulfur coverages but inhibited at higher coverages.

Foral, M.J.

1988-01-01

440

Chiral conducting surfaces via electrochemical oxidation of L-leucine-oligothiophenes.  

PubMed

Polythiophenes bearing a specific chiral center such as L-leucine have been prepared via the electrochemical oxidation of a series of L-leucine functionalized oligothiophenes (monothiophenes and terthiophenes). These oligothiophenes have been prepared through the condensation of L-leucine methyl ester and the corresponding thiophene monomers in the presence of hydroxybenzotriazole (HOBt) and N,N'-dicyclohexylcarbodiimide (DCC) followed by hydrolysis of the esters. The electroactive polymers are electrochemically stable and exhibit excellent adhesive properties on electrode surfaces (platinum, gold, and glassy carbon) as well as interesting optical properties in both doped and undoped states. Hydrogen bonds between a free amino acid (L-leucine, D-leucine, L-alanine, D-alanine, and D/L-alanine) and the L-leucine based polythiophenes (chiral conducting surface) were probed using cyclic voltammetry. Preliminary results show that the capacitive current of a modified L-leucine-polythiophene electrode decreases as a result of the formation of a hydrogen bond barrier on the surface of the chiral conducting surface accompanied with a shift of the oxidation potential. Cyclic voltammetry responses resulting from the interaction of the chiral conducting surface with L and Dfree amino acid isomers are similar. The formation of hydrogen bonds between the chiral conducting surfaces and the free amino acids was characterized by (1)H NMR. A chemical shift was observed for the N-H group in monomer 6 as a result of the hydrogen bond formation between the L-leucine methyl ester (D-leucine methyl ester, D/L-leucine methyl ester) and monomer 6. PMID:20718451

McTiernan, Christopher D; Omri, Karim; Chahma, M'hamed

2010-09-17

441

Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste  

SciTech Connect

Various forms of general and localized corrosion represent principal threats to the integrity of DOE liquid waste storage tanks. These tanks, which are of a single wall or double wall design, depending upon their age, are fabricated from welded carbon steel and contain a complex waste-form comprised of NaOH and NaNO{sub 3}, along with trace amounts of phosphate, sulfate, carbonate, and chloride. Because waste leakage can have a profound environmental impact, considerable interest exists in predicting the accumulation of corrosion damage, so as to more effectively schedule maintenance and repair. The different tasks that are being carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA) which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples in order to exactly predict the corrosion mechanisms; (7) Wavelet analysis of EC noise data from steel samples undergoing corrosion in an environment similar to that of the high level waste storage containers, to extract data pertaining to general, pitting and stress corrosion processes, from the overall data. The Point Defect Model (PDM) is directly applied as the theoretical assessment method for describing the passive film formed on iron/steels. The PDM is used to describe general corrosion in the passive region of iron. In addition, previous work suggests that pit formation is due to the coalescence of cation vacancies at the metal/film interface which would make it possible to use the PDM parameters to predict the onset of pitting. This previous work suggests that once the critical vacancy density is reached, the film ruptures to form a pit. Based upon the kinetic parameters derived for the general corrosion case, two parameters relating to the cation vacancy formation and annihilation can be calculated. These two parameters can then be applied to predict the transition from general to pitting corrosion for iron/mild steels. If cation vacancy coalescence is shown to lead to pitting, it can have a profound effect on the direction of future studies involving the onset of pitting corrosion. The work has yielded a number of important findings, including an unequivocal demonstration of the role of chloride ion in passivity breakdown on nickel in terms of cation vacancy generation within the passive film, the first detection and characterization of individual micro fracture events in stress corrosion cracking, and the determination of kinetic parameters for the generation and annihilation of point defects in the passive film on iron. The existence of coupling between the internal crack environment and the external cathodic environment, as predicted by the coupled environment fracture model (CEFM), has also been indisputably established for the AISI 4340/NaOH system. It is evident from the studies that analysis of coupling current noise is a very sensitive tool f

Digby D. Macdonald; Brian M. Marx; Sejin Ahn; Julio de Ruiz; Balaji Soundararaja; Morgan Smith; and Wendy Coulson

2008-01-15