Oxidative-Alkaline Leaching of Washed 241-SY-102 and 241-SX-101 Tank Sludges and Its Impact on Immobilized High-Level Waste

International Nuclear Information System (INIS)

Rapko, Brian M.; Geeting, John GH; Sinkov, Sergei I.; Vienna, John D.

2006-01-01

This report describes work designed to evaluate the effectiveness of alkaline permanganate contacts at selectively removing chromium from the Hanford tank sludges 241-SY-102 and 241-SX-101. The key variables examined in this study, as compared to contact with the standard conditions of stoichiometric permanganate in 3 M hydroxide at elevated temperature, were: (a) excess permanganate and hydroxide at elevated temperature, (b) the separation of an elevated temperature 3 M hydroxide leach with either a room temperature permanganate contact or an elevated temperature permanganate contact at 0.25 M hydroxide. It was determined that sequential permanganate and caustic leaching can provide as effective removal of Cr as the combined high hydroxide permanganate contact at elevated temperature while minimizing concomitant Pu dissolution

Inhibiting and healing effects of potassium permanganate for silane films

Energy Technology Data Exchange (ETDEWEB)

She, Zuxin; Li, Qing, E-mail: liqingswu@yeah.net; Wang, Shaoyin; Luo, Fei; Chen, Funan; Li, Longqin

2013-07-31

In this study, the inhibiting and healing effects of potassium permanganate for silane films were investigated, and the optimal mole ratio of MnO{sub 4}{sup −}/Cl{sup −} was also obtained. The inhibiting process and healing mechanism were studied by electrochemical measurements and scanning electron microcopy coupled with energy dispersive spectroscopy. Results demonstrated that the introduction of potassium permanganate to electrolyte could stop the development of corrosion process and the optimal inhibiting mole ratio of MnO{sub 4}{sup −}/Cl{sup −} is 2 × 10{sup −1} with a protective efficiency about 99.24%. According to its high protective efficiency and the nice results of long-term immersion test, potassium permanganate as an inhibitor could prolong the lifetime of silane films and expand its scope of application. - Highlights: • Healing sol–gel film was obtained by adding KMnO{sub 4} into electrolyte. • An optimal inhibitor mole ratio of MnO{sub 4}{sup −}/Cl{sup −} for Si sol–gel was 2 × 10{sup −1}. • The best protective efficiency was approximately 99.24%. • The inhibiting effect may be due to production of insoluble manganese hydroxide/oxide.

The impact of electrochemical reduction potentials on the electrocatalytic activity of graphene oxide toward the oxygen reduction reaction in an alkaline medium

International Nuclear Information System (INIS)

Toh, Shaw Yong; Loh, Kee Shyuan; Kamarudin, Siti Kartom; Daud, Wan Ramli Wan

2016-01-01

We report the synthesis of graphene via the electrochemical reduction of graphene oxide (GO). In this study, GO nanosheets from aqueous dispersion were pre-assembled on a glassy carbon (GC) electrode and then electrochemically reduced in 1 M KOH under various constant reduction potentials in the range of −0.6 V to −1.5 V (vs. Ag/AgCl). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses revealed that the graphitic structure was substantially restored in the resulting electrochemically reduced graphene oxide (ERGO). The ERGO electrodes exhibited significantly enhanced catalytic activity toward the oxygen reduction reaction (ORR) in an alkaline medium compared with the initial GO electrode. Of the ERGO electrodes produced at various cathodic potentials, the ERGO-1.2 V electrode, which was produced at a reduction potential of −1.2 V, demonstrated the best catalytic activity toward the ORR in an alkaline medium. The ORR on GO and ERGO electrodes was shown to proceed via a two-electron mechanism at low overpotentials. The agreement between the spectroscopy results and electrochemical measurements provide strong evidence that the enhanced ORR catalytic activity is mainly attributed to the restoration of GO’s graphitic structure. Furthermore, the ERGO-1.2 V electrode showed excellent tolerance to the methanol poisoning effect compared with a Pt/C catalyst electrode.

Reinvestigation of the role of humic acid in the oxidation of phenols by permanganate.

Science.gov (United States)

Sun, Bo; Zhang, Jing; Du, Juanshan; Qiao, Junlian; Guan, Xiaohong

2013-12-17

Humic acid (HA) affects the oxidation of phenolic compounds by permanganate, but the role of HA in the oxidation of phenols by permanganate is far from clear. The mechanisms by which HA influences the oxidation of phenols by permanganate at pH 5.0-9.0 were systematically examined in this study. The presence of HA enhanced the oxidation of phenolic compounds by permanganate at pH ≤7.0, with greater enhancement at lower pH values. The presence of HA facilitated the in situ formation of MnO2, implying the importance of reductive moieties of HA in this reaction. This was supported by the finding that HA preoxidized by ozone showed enhancements in the oxidation of phenols by permanganate at pH 5.0-6.0 smaller than those seen with pristine HA. The good correlation between HA-induced improvement in the oxidation rates of phenols by permanganate and those by preformed colloidal MnO2 at pH 5.0 confirmed that contribution of MnO2 formed in situ for the oxidation of phenols under this condition. The differences in the influence of Na2S2O3 and HA on the oxidation of phenol by permanganate revealed the fact that the continuous generation of fresh MnO2 and stabilization of the MnO2 formed in situ by HA were crucial for the HA-induced enhancement of the oxidation of phenols by permanganate at pH ≤7.0. The consumption of permanganate by HA and the poor oxidation ability of in situ-generated MnO2 under alkaline conditions resulted in the slightly negative effect of HA on the degradation rates of phenols by permanganate at pH >7.0.

Permanganate Degradation of Reillex HPQ Ion Exchange Resin for Use in HB-Line

International Nuclear Information System (INIS)

Walker, B.W.

1999-01-01

This study evaluated the use of Reillex TM HPQ resin as a replacement for the Ionac A-641 resin currently authorized for use in H B-Line. The study concentrated on the ability of the existing alkaline permanganate digestion process to convert spent resin for disposal

Corrosion behaviour of chemical conversion treatments on as-cast Mg-Al alloys: Electrochemical and non-electrochemical methods

Energy Technology Data Exchange (ETDEWEB)

Rocca, E. [Institut Jean Lamour UMR CNRS 7198, Nancy Universite - Corrosion Group, B.P. 70239, 54506 Vandoeuvre-Les-Nancy (France)], E-mail: emmanuel.rocca@lcsm.uhp-nancy.fr; Juers, C.; Steinmetz, J. [Institut Jean Lamour UMR CNRS 7198, Nancy Universite - Corrosion Group, B.P. 70239, 54506 Vandoeuvre-Les-Nancy (France)

2010-06-15

Magnesium alloys are often used in as-cast conditions. So, the aim of this work is to characterize the corrosion protection of as-cast AZ91D alloys coated with simple chemical conversion (phosphate-permanganate, and cerium-based coatings). With the two coatings, the electrochemical measurements show that the corrosion protection is due to both the inhibition of cathodic and anodic reactions, because of the presence of stable CeO{sub 2} or manganese oxides in basic pH. Nevertheless, the non-electrochemical tests of corrosion are required to bring to light the healing effect of phosphate-permanganate coating compared to Ce-coating and to describe the corrosion behaviour completely. Finally phosphoric and soda pickling associated to phosphate-permanganate conversion treatment or cerium coating are ecologically efficient alternatives to fluoride-based pickling and the chromating treatment.

Molybdate and molybdate/permanganate conversion coatings on Mg-8.5Li alloy

International Nuclear Information System (INIS)

Wang Guixiang; Zhang Milin; Wu Ruizhi

2012-01-01

A novel environment-friendly conversion coating for Mg-8.5Li alloy was obtained by immersing in a solution of molybdate. The concentration of ammonium molybdate and the addition of potassium permanganate were discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg-8.5Li alloy and conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The results showed that the coatings with cracked morphology were homogeneous and uniform. The conversion coatings were mainly composed of metal-oxide as detected by XPS. The results of electrochemical measurement and weight loss measurement revealed that the molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating, and the molybdate/permanganate conversion coating had lower corrosion current density and higher coating resistance than the molybdate conversion coating.

Molybdate and molybdate/permanganate conversion coatings on Mg-8.5Li alloy

Energy Technology Data Exchange (ETDEWEB)

Wang Guixiang, E-mail: wgx0357@126.com [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang Milin; Wu Ruizhi [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

2012-01-15

A novel environment-friendly conversion coating for Mg-8.5Li alloy was obtained by immersing in a solution of molybdate. The concentration of ammonium molybdate and the addition of potassium permanganate were discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg-8.5Li alloy and conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The results showed that the coatings with cracked morphology were homogeneous and uniform. The conversion coatings were mainly composed of metal-oxide as detected by XPS. The results of electrochemical measurement and weight loss measurement revealed that the molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating, and the molybdate/permanganate conversion coating had lower corrosion current density and higher coating resistance than the molybdate conversion coating.

75 FR 51112 - Potassium Permanganate From China

Science.gov (United States)

2010-08-18

... Permanganate From China AGENCY: United States International Trade Commission. ACTION: Scheduling of an expedited five-year review concerning the antidumping duty order on potassium permanganate from China... of the antidumping duty order on potassium permanganate from China would be likely to lead to...

Determination of cyanide using a chemiluminescence system composed of permanganate, rhodamine B, and gold nanoparticles

International Nuclear Information System (INIS)

Amjadi, Mohammad; Hassanzadeh, Javad; Manzoori, Jamshid L.

2014-01-01

We describe a new chemiluminescence (CL) system based on the oxidation of rhodamine B (RhoB) with alkaline potassium permanganate in the presence of gold nanoparticles (Au-NPs) and anionic detergent sodium dodecyl sulfate. Free RhoB is weakly chemiluminescent when oxidized with permanganate at alkaline pH values. However, a remarkably strong enhancement of CL is observed in the presence of Au-NPs, probably due to a strong interaction between RhoB and the NPs. The possible mechanism was studied via recording the CL emission. It is also found that the intensity of CL gradually decreases in the presence of cyanide due to its interaction with the Au-NPs. The relation between the decreased CL intensity and cyanide concentration was exploited to develop a method for the determination of cyanide in the 0.01–0.5 μM concentration range, with a detection limit of 2.8 nM. The method was used to determine cyanide in spiked water, urine, and serum. (author)

Degradation of progestagens by oxidation with potassium permanganate in wastewater effluents.

Science.gov (United States)

Fayad, Paul B; Zamyadi, Arash; Broseus, Romain; Prévost, Michèle; Sauvé, Sébastien

2013-01-01

This study investigated the oxidation of selected progestagenic steroid hormones by potassium permanganate at pH 6.0 and 8.0 in ultrapure water and wastewater effluents, using bench-scale assays. Second order rate constants for the reaction of potassium permanganate with progestagens (levonorgestrel, medroxyprogesterone, norethindrone and progesterone) was determined as a function of pH, presence of natural organic matter and temperature. This work also illustrates the advantages of using a novel analytical method, the laser diode thermal desorption (LDTD-APCI) interface coupled to tandem mass spectrometry apparatus, allowing for the quick determination of oxidation rate constants and increasing sample throughput. The second-order rate constants for progestagens with permanganate determined in bench-scale experiments ranged from 23 to 368 M(-1) sec(-1) in both wastewater and ultrapure waters with pH values of 6.0 and 8.0. Two pairs of progestagens exhibited similar reaction rate constants, i.e. progesterone and medroxyprogesterone (23 to 80 M(-1) sec(-1) in ultrapure water and 26 to 149 M(-1) sec(-1) in wastewaters, at pH 6.0 and 8.0) and levonorgestrel and norethindrone (179 to 224 M(-1) sec(-1) in ultrapure water and 180 to 368 M(-1) sec(-1) in wastewaters, at pH 6.0 and 8.0). The presence of dissolved natural organic matter and the pH conditions improved the oxidation rate constants for progestagens with potassium permanganate only at alkaline pH. Reaction rates measured in Milli-Q water could therefore be used to provide conservative estimates for the oxidation rates of the four selected progestagens in wastewaters when exposed to potassium permanganate. The progestagen removal efficiencies was lower for progesterone and medroxyprogesterone (48 to 87 %) than for levonorgestrel and norethindrone (78 to 97%) in Milli-Q and wastewaters at pH 6.0-8.2 using potassium permanganate dosages of 1 to 5 mg L(-1) after contact times of 10 to 60 min. This

Potassium Permanganate as an Alternative for Gold Mining Wastewater Treatment

Science.gov (United States)

Ordiales, M.; Fernández, D.; Verdeja, L. F.; Sancho, J.

2015-09-01

The feasibility of using potassium permanganate as a reagent for cyanide oxidation in wastewater was experimentally studied. Both artificial and production wastewater from two different gold mines were tested. The experiments had three goals: determine the optimum reagent concentration and reaction time required to achieve total cyanide removal, obtain knowledge of the reaction kinetics, and improve the management of the amount of reagent. The results indicate that potassium permanganate is an effective and reliable oxidizing agent for the removal of cyanide from gold mining wastewater.

Development of an Alternative Treatment Scheme for Sr/TRU Removal: Permanganate Treatment of AN-107 Waste

International Nuclear Information System (INIS)

Hallen, R.T.; Bryan, S.A.; Hoopes, F.V.

2000-01-01

A number of Hanford tanks received waste containing organic complexants, which increase the volubility of Sr-90 and transuranic (TRU) elements. Wastes from these tanks require additional pretreatment to remove Sr-90 and TRU for immobilization as low activity waste (Waste Envelope C). The baseline pretreatment process for Sr/TRU removal was isotopic exchange and precipitation with added strontium and iron. However, studies at both Battelle and Savannah River Technology Center (SRTC) have shown that the Sr/Fe precipitates were very difficult to filter. This was a result of the formation of poor filtering iron solids. An alternate treatment technology was needed for Sr/TRU removal. Battelle had demonstrated that permanganate treatment was effective for decontaminating waste samples from Hanford Tank SY-101 and proposed that permanganate be examined as an alternative Sr/TRU removal scheme for complexant-containing tank wastes such as AW107. Battelle conducted preliminary small-scale experiments to determine the effectiveness of permanganate treatment with AN-107 waste samples that had been archived at Battelle from earlier studies. Three series of experiments were performed to evaluate conditions that provided adequate Sr/TRU decontamination using permanganate treatment. The final series included experiments with actual AN-107 diluted feed that had been obtained specifically for BNFL process testing. Conditions that provided adequate Sr/TRU decontamination were identified. A free hydroxide concentration of 0.5M provided adequate decontamination with added Sr of 0.05M and permanganate of 0.03M for archived AN-107. The best results were obtained when reagents were added in the sequence Sr followed by permanganate with the waste at ambient temperature. The reaction conditions for Sr/TRU removal will be further evaluated with a 1-L batch of archived AN-107, which will provide a large enough volume of waste to conduct crossflow filtration studies (Hallen et al. 2000a)

Development of an Alternative Treatment Scheme for Sr/TRU Removal: Permanganate Treatment of AN-107 Waste

Energy Technology Data Exchange (ETDEWEB)

RT Hallen; SA Bryan; FV Hoopes

2000-08-04

A number of Hanford tanks received waste containing organic complexants, which increase the volubility of Sr-90 and transuranic (TRU) elements. Wastes from these tanks require additional pretreatment to remove Sr-90 and TRU for immobilization as low activity waste (Waste Envelope C). The baseline pretreatment process for Sr/TRU removal was isotopic exchange and precipitation with added strontium and iron. However, studies at both Battelle and Savannah River Technology Center (SRTC) have shown that the Sr/Fe precipitates were very difficult to filter. This was a result of the formation of poor filtering iron solids. An alternate treatment technology was needed for Sr/TRU removal. Battelle had demonstrated that permanganate treatment was effective for decontaminating waste samples from Hanford Tank SY-101 and proposed that permanganate be examined as an alternative Sr/TRU removal scheme for complexant-containing tank wastes such as AW107. Battelle conducted preliminary small-scale experiments to determine the effectiveness of permanganate treatment with AN-107 waste samples that had been archived at Battelle from earlier studies. Three series of experiments were performed to evaluate conditions that provided adequate Sr/TRU decontamination using permanganate treatment. The final series included experiments with actual AN-107 diluted feed that had been obtained specifically for BNFL process testing. Conditions that provided adequate Sr/TRU decontamination were identified. A free hydroxide concentration of 0.5M provided adequate decontamination with added Sr of 0.05M and permanganate of 0.03M for archived AN-107. The best results were obtained when reagents were added in the sequence Sr followed by permanganate with the waste at ambient temperature. The reaction conditions for Sr/TRU removal will be further evaluated with a 1-L batch of archived AN-107, which will provide a large enough volume of waste to conduct crossflow filtration studies (Hallen et al. 2000a).

Electrochemical Performance of Low-Carbon Steel in Alkaline Model Solutions Containing Hybrid Aggregates

NARCIS (Netherlands)

Koleva, D.A.; Hu, J.; De Wit, J.H.W.; Boshkov, N.; Radeva, T.; Milkova, V.; Van Breugel, K.

2010-01-01

This work reports on the electrochemical performance of low-carbon steel electrodes in model alkaline solutions in the presence of 4.9.10-4 g/l hybrid aggregates i.e. cement extract, containing PDADMAC (poly (diallyl, dimethyl ammonium chloride) / PAA (Poly (acrylic acid)/ PDADMAC over a CaO core.

Alkaline electrochemical advanced oxidation process for chromium oxidation at graphitized multi-walled carbon nanotubes.

Science.gov (United States)

Xue, Yudong; Zheng, Shili; Sun, Zhi; Zhang, Yi; Jin, Wei

2017-09-01

Alkaline electrochemical advanced oxidation processes for chromium oxidation and Cr-contaminated waste disposal were reported in this study. The highly graphitized multi-walled carbon nanotubes g-MWCNTs modified electrode was prepared for the in-situ electrochemical generation of HO 2 - . RRDE test results illustrated that g-MWCNTs exhibited much higher two-electron oxygen reduction activity than other nanocarbon materials with peak current density of 1.24 mA cm -2 , %HO 2 - of 77.0% and onset potential of -0.15 V (vs. Hg/HgO). It was originated from the highly graphitized structure and good electrical conductivity as illustrated from the Raman, XRD and EIS characterizations, respectively. Large amount of reactive oxygen species (HO 2 - and ·OH) were in-situ electro-generated from the two-electron oxygen reduction and chromium-induced alkaline electro-Fenton-like reaction. The oxidation of Cr(III) was efficiently achieved within 90 min and the conversion ratio maintained more than 95% of the original value after stability test, offering an efficient and green approach for the utilization of Cr-containing wastes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Flowsheet Validation For The Permanganate Digestion Of REILLEX(trademark) HPQ Anion Resin

International Nuclear Information System (INIS)

Kyser, E.

2009-01-01

The flowsheet for the digestion of Reillex(trademark) HPQ was validated both under the traditional alkaline conditions and under strongly acidic conditions. Due to difficulty in performing a pH adjustment in the large tank where this flowsheet must be performed, the recommended digestion conditions were changed from pH 8-10 to 8 M HNO 3 . Thus, no pH adjustment of the solution is required prior to performing the permanganate addition and digestion and the need to sample the digestion tank to confirm appropriate pH range for digestion may be avoided. Neutralization of the acidic digestion solution will be performed after completion of the resin digestion cycle. The amount of permanganate required for this type of resin (Reillex(trademark) HPQ) was increased from 1 kg/L resin to 4 kg/L resin to reduce the amount of residual resin solids to a minimal amount ( 2 ) solids (1.71 kg/L resin) and involves the generation of a significant liquid volume due to the low solubility of permanganate. However, since only two batches of resin (40 L each) are expected to be digested, the total waste generated is limited.

A study of the decomposition of silver permanganate at high temperatures with an x-ray diffractometer

International Nuclear Information System (INIS)

De Witt, B.

1978-12-01

A study is made of the thermal decay products of silver permanganate at temperatures between 100 degrees Celsius and 800 degrees Celsius. Previous studies have shown that silver permanganate and the decomposition of silver permanganate decay into an amorphous product and remains in that state until the temperature is higher than 350 degrees Celsius. The amorphous phase is tested at different temperatures

Chemical effects of nuclear transformations in metal permanganates

International Nuclear Information System (INIS)

Lee, Byung Hun; Kim, Bong Whan

1986-01-01

The chemical effects resulting from the capture of the thermal neutrons by manganese in different crystalline permanganates, that is, potassium permanganate,sodium permanganate, silver permanganate, barium permanganate and ammonium permanganate, have been investigated. The distribution of radioactive manganese formed has been determined by using different absorbents and ion-exchangers, that is,manganese dioxide, alumina, Zeolite A-3, Kaolinite and Dowex-50. The distribution of radioactive manganese in various adsorbents and ion-exchangers has almost similar result for each permanganate. The affinity for radioactive manganous ion is greatest for Dewex-50. A significant increase of retention is shown through the thermal annealing and the retention depends on the first ionization potential of metal ion in permanganates. (Author)

Kinetics and Mechanistic Study of the Ruthenium(III Catalysed Oxidative Decarboxylation of L-Proline by Alkaline Heptavalent Manganese (Stopped flow technique

Directory of Open Access Journals (Sweden)

R. S. Shettar

2005-01-01

Full Text Available The kinetics of ruthenium(III catalysed oxidation of L-Proline by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically using a rapid kinetic accessory. The reaction between permanganate and L-Proline in alkaline medium exhibits 2:1 stoichiometry (KMnO4: L-Proline. The reaction shows first order dependence on [permanganate] and [ruthenium(III] and apparent less than unit order dependence each in L-Proline and alkali concentrations. Reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Initial addition of reaction products did not affect the rate significantly. A mechanism involving the formation of a complex between catalyst and substrate has been proposed. The activation parameters were computed with respect to the slow step of the mechanism and discussed

Reaction of lithium, sodium and potassium polyphosphates with potassium permanganate at elevated temperatures

International Nuclear Information System (INIS)

Paderova, L.V.; Onuchina, T.V.; Kochergin, V.P.

1996-01-01

A study was made on destruction of molten polyphosphates of alkaline metals by potassium permanganate during change of KMnO 4 content, test time and temperature. Ortho-, di, tri- and tetraphosphate-anions, as well as manganese compounds with different oxidation degree were revealed in products of component interaction. Empirical equations of the dependence of the value of average molecular mass on change of melt temperature were derived. 11 refs.; 2 figs.; 2 tabs

21 CFR 250.108 - Potassium permanganate preparations as prescription drugs.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Potassium permanganate preparations as... or Prescription Status of Specific Drugs § 250.108 Potassium permanganate preparations as... women resulting from the misuse of potassium permanganate in an effort to induce abortion. Reports from...

Summary technical report on the electrochemical treatment of alkaline nuclear wastes

International Nuclear Information System (INIS)

Hobbs, D.T.

1994-01-01

This report summarizes the laboratory studies investigating the electrolytic treatment of alkaline solutions carried out under the direction of the Savannah River Technology Center from 1985-1992. Electrolytic treatment has been demonstrated at the laboratory scale to be feasible for the destruction of nitrate and nitrite and the removal of radioactive species such as 99 Tc and 106 Ru from Savannah River Site (SRS) decontaminated salt solution and other alkaline wastes. The reaction rate and current efficiency for the removal of these species are dependent on cell configuration, electrode material, nature of electrode surface, waste composition, current density, and temperature. Nitrogen, ammonia, and nitrous oxide have been identified as the nitrogen-containing reaction products from the electrochemical reduction of nitrate and nitrite under alkaline conditions. The reaction mechanism for the reduction is very complex. Voltammetric studies indicated that the electrode reactions involve surface phenomena and are not necessarily mass transfer controlled. In an undivided cell, results suggest an electrocatalytic role for oxygen via the generation of the superoxide anion. In general, more efficient reduction of nitrite and nitrate occurs at cathode materials with higher overpotentials for hydrogen evolution. Nitrate and nitrite destruction has also been demonstrated in engineering-scale flow reactors. In flow reactors, the nitrate/nitrite destruction efficiency is improved with an increase in the current density, temperature, and when the cell is operated in a divided cell configuration. Nafion reg-sign cation exchange membranes have exhibited good stability and consistent performance as separators in the divided-cell tests. The membranes were also shown to be unaffected by radiation at doses approximating four years of cell operation in treating decontaminated salt solution

75 FR 23298 - Potassium Permanganate From China

Science.gov (United States)

2010-05-03

... Permanganate From China AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on potassium permanganate from China. SUMMARY: The... on potassium permanganate from China would be likely to lead to continuation or recurrence of...

Oxygen isotope effect on 55Mn nuclear magnetic shielding in permanganate

International Nuclear Information System (INIS)

Haase, A.R.; Lutz, O.; Mueller, M.; Nolle, A.

1976-01-01

By Fourier transform NMR spectroscopy the 55 Mn resonance lines of the different permanganate species 55 Mn 16 Osub(4-n) 18 Osub(n) - (n=0,1,2,3,4) have been resolved in aqueous solutions of potassium permanganate. An isotope effect on the Larmor frequency of 55 Mn of (0.599 +- 0.015)ppm to lower frequency was found for the substition of an 16 O atom by an 18 O atom in the permanganate ion. An oxygen exchange rate in the permanganate-water system is given. (orig.) [de

Growth of permanganate conversion coating on 2024-Al alloy

International Nuclear Information System (INIS)

Kulinich, S.A.; Akhtar, A.S.; Wong, P.C.; Wong, K.C.; Mitchell, K.A.R.

2007-01-01

The growth of permanganate conversion coating on aluminum 2024-T3 alloy has been studied by characterizing, with scanning Auger microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy, the coatings formed by immersion of the alloy in the coating bath (containing KMnO 4 and Na 2 B 4 O 7 , pH 9.1) for different periods of time and at different temperatures. At room temperature, during the first 1-5 min of immersion, MnO 2 deposits are formed only on the second-phase intermetallic particles (of Al-Cu-Mg and Al-Cu-Fe-Mn types), but the coating starts to develop on the Al matrix surface after 5-10 min. The coating slows down and stops after about 150 min, with a thinner deposit over the alloy matrix. The process is accelerated at higher temperatures, for example at 68 deg. C it self-limits after about 3 min. The electrochemical growth process appears to follow that established for the chromate conversion coatings, although XPS does not detect significant MnO 4 - incorporation into the permanganate coatings

Microbial Community Response of an Organohalide Respiring Enrichment Culture to Permanganate Oxidation.

Science.gov (United States)

Sutton, Nora B; Atashgahi, Siavash; Saccenti, Edoardo; Grotenhuis, Tim; Smidt, Hauke; Rijnaarts, Huub H M

2015-01-01

While in situ chemical oxidation is often used to remediate tetrachloroethene (PCE) contaminated locations, very little is known about its influence on microbial composition and organohalide respiration (OHR) activity. Here, we investigate the impact of oxidation with permanganate on OHR rates, the abundance of organohalide respiring bacteria (OHRB) and reductive dehalogenase (rdh) genes using quantitative PCR, and microbial community composition through sequencing of 16S rRNA genes. A PCE degrading enrichment was repeatedly treated with low (25 μmol), medium (50 μmol), or high (100 μmol) permanganate doses, or no oxidant treatment (biotic control). Low and medium treatments led to higher OHR rates and enrichment of several OHRB and rdh genes, as compared to the biotic control. Improved degradation rates can be attributed to enrichment of (1) OHRB able to also utilize Mn oxides as a terminal electron acceptor and (2) non-dechlorinating community members of the Clostridiales and Deltaproteobacteria possibly supporting OHRB by providing essential co-factors. In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2-4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control. High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB. Although OTUs classified within the OHR-supportive order Clostridiales and OHRB increased in abundance over the course of 213 days following the final 100 μmol permanganate treatment, only limited regeneration of PCE dechlorination was observed in one of three microcosms, suggesting strong chemical oxidation treatments can irreversibly disrupt OHR. Overall, this detailed investigation into dose

Suicidal ingestion of potassium permanganate crystals: a rare encounter.

Science.gov (United States)

Karthik, Ravikanti; Veerendranath, Hari Prasad Kanakapura; Wali, Siddraj; Mohan, Murali N T; Kumar, Praveen A C; Trimurty, Gaganam

2014-01-01

Potassium permanganate poisoning is not common. Although Symptoms of potassium permanganate ingestion are gastrointestinal and Complications due to ingestion of potassium permanganate include cardiovascular depression, hepatic and renal damage, upper airway obstruction, bleeding tendency and methemoglobinemia. Gastric damage due to potassium permanganate has rarely been reported previously. We are reporting a 34-year old female patient who presented to our Emergency Department after suicidal ingestion of potassium permanganate crystals. After treatment, the patient was discharged home on the 8(th) day after admission. So we conclude that Emergency endoscopy has a significant role in diagnosis and management of potassium permanganate ingestion.

Two-phase titration of cerium(III) by permanganate

International Nuclear Information System (INIS)

Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

1987-01-01

This paper presents a method for the two-phase titrimetric determination of cerium(III) with permanganate which does not require an expenditure of sugar and preliminary removal of chlorides and nitrates. The interaction of cerium(III) with permanganate at room temperature was studied as a function of the pH, the concentration of pyrophosphate, tetraphenylphosphonium (TPP), permanganate, and extraneous compounds, the rate of titration, and the time of stay of the solution in air before titration. The investigations were conducted according to the following methodology: water, solution of cerium(III) pyrophosphate, and TPP were introduced into an Erlenmeyer flask with a side branch near the bottom for clearer observation of the color of the chloroform phase. The authors established the given pH value, poured the water into a volume of 50 ml, and added chloroform. The result was titrated with permanganate solutions of various concentrations until a violet color appeared in the chloroform phase

Permanganate diffusion and reaction in sedimentary rocks.

Science.gov (United States)

Huang, Qiuyuan; Dong, Hailiang; Towne, Rachael M; Fischer, Timothy B; Schaefer, Charles E

2014-04-01

In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate. Copyright © 2014 Elsevier B.V. All rights reserved.

Crystal structures and thermal decomposition of permanganates AE[MnO_4]_2 . n H_2O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

International Nuclear Information System (INIS)

Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas

2017-01-01

Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO_4]_2 . 4 H_2O, Sr[MnO_4]_2 . 3 H_2O and Ba[MnO_4]_2 are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO_4]_2 a long time ago, we employed a cation-exchange column loaded with Ba"2"+ cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO_4]_2 . 4 H_2O exhibiting [CaO_8] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO_4]_2 . 3 H_2O with [SrO_1_0] polyhedra adopts the cubic space group P2_13 with a=964.19(7) pm and Z=4. So the harder the AE"2"+ cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO_4]_2 in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO_1_2] polyhedra. During the thermal decomposition of Ca[MnO_4]_2 . 4 H_2O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H_2O molecule at 157 C. The crystal structure of Sr[MnO_4]_2 . 3 H_2O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn_2O_3 and the oxomanganates(III,IV) AEMn_3O_6 (AE=Ca and Sr) remain as final decomposition products at 800 C next to amorphous phases. On the other hand, the already anhydrous Ba[MnO_4]_2 thermally decomposes to hollandite-type BaMn_8O_1_6 and BaMnO_3 at 800 C.

An electrochemical method to prepare of Pd/Cu2O/MWCNT nanostructure as an anode electrocatalyst for alkaline direct ethanol fuel cells

International Nuclear Information System (INIS)

Rostami, Hussein; Rostami, Abbas Ali; Omrani, Abdollah

2016-01-01

This study reports an electrochemical method to fabrication of palladium nanoparticles (Pd NPs) promoted with cuprous oxide (Cu 2 O) supported on multi-walled carbon nanotube (Pd/Cu 2 O/MWCNT). First, Cu 2 O is electrodeposited on treated MWCNTs in the optimum deposition conditions. Then, the Pd nanostructure is electrochemically fabricated on Cu 2 O/MWCNT electrode by cycling the potential between +0.5 to −1.0 V in negative direction. The prepared electrodes are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The electrocatalytic performance of Pd/Cu 2 O/MWCNT electrocatalyst for ethanol oxidation reaction (EOR) is investigated by cyclic voltammetric (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) measurements. The formation of the Pd/Cu 2 O/MWCNT is confirmed by EDX and XRD techniques. The onset potential of Pd/Cu 2 O/MWCNT shifts to negative values by 120 mV compared to the onset potential of Pd/MWCNT. Much higher I f /I b value is obtained for Pd/Cu 2 O/MWCNT compared to other Pd-based catalysts indicating Cu 2 O could significantly enhance the stability and CO poisoning tolerance of the Pd towards ethanol electrooxidation. The results revealed that the prepared Pd/Cu 2 O/MWCNT catalyst can be a promising anode catalyst for alkaline direct ethanol fuel cells.

75 FR 63856 - Potassium Permanganate From China Determination

Science.gov (United States)

2010-10-18

... Permanganate From China Determination On the basis of the record \\1\\ developed in the subject five-year review... potassium permanganate from China would be likely to lead to continuation or recurrence of material injury... Commission are contained in USITC Publication 4183 (September 2010), entitled Potassium Permanganate from...

Suicidal Ingestion of Potassium Permanganate Crystals: A Rare Encounter

OpenAIRE

Karthik, Ravikanti; Veerendranath, Hari Prasad Kanakapura; Wali, Siddraj; Mohan, Murali N T; Kumar, Praveen A. C.; Trimurty, Gaganam

2014-01-01

Potassium permanganate poisoning is not common. Although Symptoms of potassium permanganate ingestion are gastrointestinal and Complications due to ingestion of potassium permanganate include cardiovascular depression, hepatic and renal damage, upper airway obstruction, bleeding tendency and methemoglobinemia. Gastric damage due to potassium permanganate has rarely been reported previously. We are reporting a 34-year old female patient who presented to our Emergency Department after suicidal ...

Electrochemical catalytic treatment of phenol wastewater

International Nuclear Information System (INIS)

Ma Hongzhu; Zhang Xinhai; Ma Qingliang; Wang Bo

2009-01-01

The slurry bed catalytic treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. In this paper, the electrochemical oxidation of phenol in synthetic wastewater catalyzed by ferric sulfate and potassium permanganate adsorbed onto active bentonite in slurry bed electrolytic reactor with graphite electrode has been investigated. In order to determine the optimum operating condition, the orthogonal experiments were devised and the results revealed that the system of ferric sulfate, potassium permanganate and active bentonite showed a high catalytic efficiency on the process of electrochemical oxidation phenol in initial pH 5. When the initial concentration of phenol was 0.52 g/L (the initial COD 1214 mg/L), up to 99% chemical oxygen demand (COD) removal was obtained in 40 min. According to the experimental results, a possible mechanism of catalytic degradation of phenol was proposed. Environmental estimation was also done and the results showed that the treated wastewater have little impact on plant growth and could totally be applied to irrigation.

Electrochemical catalytic treatment of phenol wastewater

Energy Technology Data Exchange (ETDEWEB)

Ma Hongzhu, E-mail: hzmachem@snnu.edu.cn [Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Zhang Xinhai [Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Ma Qingliang [Department of Applied Physics, College of Sciences, Taiyuan University of Technology, 030024 Taiyuan (China); Wang Bo [Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

2009-06-15

The slurry bed catalytic treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. In this paper, the electrochemical oxidation of phenol in synthetic wastewater catalyzed by ferric sulfate and potassium permanganate adsorbed onto active bentonite in slurry bed electrolytic reactor with graphite electrode has been investigated. In order to determine the optimum operating condition, the orthogonal experiments were devised and the results revealed that the system of ferric sulfate, potassium permanganate and active bentonite showed a high catalytic efficiency on the process of electrochemical oxidation phenol in initial pH 5. When the initial concentration of phenol was 0.52 g/L (the initial COD 1214 mg/L), up to 99% chemical oxygen demand (COD) removal was obtained in 40 min. According to the experimental results, a possible mechanism of catalytic degradation of phenol was proposed. Environmental estimation was also done and the results showed that the treated wastewater have little impact on plant growth and could totally be applied to irrigation.

Oxidative degradation of pentachlorophenol by permanganate for ISCO application.

Science.gov (United States)

Matta, Roger; Chiron, Serge

2018-03-01

Potassium permanganate (KMnO 4 ) has been an effective technology for the in situ chemical oxidation (ISCO) of many organic compounds including chlorinated alkanes and alkenes, but it has rarely been applied for oxidizing aromatic organochlorines. This study confirms the ability of permanganate to oxidize an aromatic chlorinated compound, pentachlorophenol (PCP), in an efficient manner at neutral pH. The rate of the reaction between KMnO 4 and PCP was calculated and the results indicated that the reaction between PCP and permanganate is relatively fast with a second-order rate constant k″ ∼ 30 M -1  s -1 . Besides the kinetic aspect, the authors identified the main reaction by-products, and proposed a possible reaction mechanism scheme. The general pathway shows the formation of chlorinated intermediates, and ultimately, the complete mineralization to chloride, water, and CO 2 confirmed by total organic carbon and chloride measurement in solution. Flow-through column experiments, consisting of flushing a PCP-contaminated sandy or natural soil with oxidant, showed the good ability of permanganate to eliminate the pollutant. After 24 h of treatment, 77% and 56% of PCP abatement were obtained for sandy and natural soil, respectively. These findings show the high potential of permanganate for the in situ remediation of aromatic organochlorine contaminated soils.

Electrochemical kinetic and mass transfer model for direct ethanol alkaline fuel cell (DEAFC)

Science.gov (United States)

Abdullah, S.; Kamarudin, S. K.; Hasran, U. A.; Masdar, M. S.; Daud, W. R. W.

2016-07-01

A mathematical model is developed for a liquid-feed DEAFC incorporating an alkaline anion-exchange membrane. The one-dimensional mass transport of chemical species is modelled using isothermal, single-phase and steady-state assumptions. The anode and cathode electrochemical reactions use the Tafel kinetics approach, with two limiting cases, for the reaction order. The model fully accounts for the mixed potential effects of ethanol oxidation at the cathode due to ethanol crossover via an alkaline anion-exchange membrane. In contrast to a polymer electrolyte membrane model, the current model considers the flux of ethanol at the membrane as the difference between diffusive and electroosmotic effects. The model is used to investigate the effects of the ethanol and alkali inlet feed concentrations at the anode. The model predicts that the cell performance is almost identical for different ethanol concentrations at a low current density. Moreover, the model results show that feeding the DEAFC with 5 M NaOH and 3 M ethanol at specific operating conditions yields a better performance at a higher current density. Furthermore, the model indicates that crossover effects on the DEAFC performance are significant. The cell performance decrease from its theoretical value when a parasitic current is enabled in the model.

The electrochemical behaviour of stainless steel AISI 304 in alkaline solutions with different pH in the presence of chlorides

International Nuclear Information System (INIS)

Freire, L.; Carmezim, M.J.; Ferreira, M.G.S.; Montemor, M.F.

2011-01-01

Highlights: → The passivation and passivation breakdown of AISI 304 in alkaline solutions with different pH was studied. → The electrochemical behaviour and the corrosion resistance in chloride environments were evaluated using d.c. potentiodynamic polarization and electrochemical impedance spectroscopy. → The results were modelled using a hierarchically distributed circuit and revealed a more susceptible surface at pH 9. → The passive film characterization was carried out by SEM and EDS analysis, revealing the existence of MnS inclusions and the increase of Cr/Fe ratio in the attacked areas, preferably the vicinity of those inclusions. - Abstract: Nowadays, stainless steel reinforcements appear as an effective solution to increase the durability of reinforced concrete structures exposed to very aggressive environments. AISI 304 is widely used for this purpose. Although the improved durability of reinforcing AISI 304, when compared to carbon steel, there is a high probability of pitting susceptibility in the presence of chlorides. Thus, the present work aims at studying the passivation and passivation breakdown of AISI 304 in alkaline solutions of different pH (pH from 13 to 9), simulating the interstitial concrete electrolyte. These solutions were contaminated with different concentrations of chloride ions (3% and 10%, as NaCl). The electrochemical behaviour was evaluated by d.c. potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The morphological features and the changes observed in the surface composition were evaluated by Scanning Electron Microscopy (SEM) together with EDS chemical analysis. The results evidence that pH plays an important role in the evolution of the film resistance and charge transfer processes. Moreover, the effect is highly dependent upon the chloride content and immersion time.

The state of permanganate with relation to in situ chemical oxidation

International Nuclear Information System (INIS)

Veronda, Brenda; Dingens, Matthew

2007-01-01

In Situ Chemical Oxidation (ISCO) with permanganate had its beginnings over 10 years ago. Since that time, many sites have been successfully treated for organic compounds including chlorinated ethenes (perchloroethylene, trichloroethylene, etc.) phenols, explosives such as RDX, and many other organics. The successful application of ISCO with permanganate requires the integration of many site-specific factors into the remedial design. ISCO with permanganate is an effective technology, not only for its oxidative properties and persistence, but also for its application flexibility to remediate soil and groundwater. The merits of any type of treatment technology can be assessed in terms of effectiveness, ease of use, reaction rate, and cost. The use of permanganate for in situ chemical oxidation results in the complete mineralization of TCE and PCE and can result in treatment levels below detection limits. Permanganate is a single component oxidizer, which is easily handled, mixed and distributed to the subsurface. Permanganate is also inexpensive to design and implement as compared to other technologies. This presentation will provide a general overview of the application and safety aspects of ISCO with permanganate. This paper will discuss the advantages and limitations of this technology, typical cost ranges, site evaluation and application technologies. (authors)

Ru(III) catalyzed permanganate oxidation of aniline at environmentally relevant pH.

Science.gov (United States)

Zhang, Jing; Zhang, Ying; Wang, Hui; Guan, Xiaohong

2014-07-01

Ru(III) was employed as catalyst for aniline oxidation by permanganate at environmentally relevant pH for the first time. Ru(III) could significantly improve the oxidation rate of aniline by 5-24 times with its concentration increasing from 2.5 to 15 μmol/L. The reaction of Ru(III) catalyzed permanganate oxidation of aniline was first-order with respect to aniline, permanganate and Ru(III), respectively. Thus the oxidation kinetics can be described by a third-order rate law. Aniline degradation by Ru(III) catalyzed permanganate oxidation was markedly influenced by pH, and the second-order rate constant (ktapp) decreased from 643.20 to 2.67 (mol/L)⁻¹sec⁻¹ with increasing pH from 4.0 to 9.0, which was possibly due to the decrease of permanganate oxidation potential with increasing pH. In both the uncatalytic and catalytic permanganate oxidation, six byproducts of aniline were identified in UPLC-MS/MS analysis. Ru(III), as an electron shuttle, was oxidized by permanganate to Ru(VI) and Ru(VII), which acted the co-oxidants for decomposition of aniline. Although Ru(III) could catalyze permanganate oxidation of aniline effectively, dosing homogeneous Ru(III) into water would lead to a second pollution. Therefore, efforts would be made to investigate the catalytic performance of supported Ru(III) toward permanganate oxidation in our future study. Copyright © 2014. Published by Elsevier B.V.

Potassium permanganate ingestion as a suicide attempt

Directory of Open Access Journals (Sweden)

Sebnem Eren Cevik

2012-02-01

Full Text Available Potassium permanganate is a highly corrosive, water-soluble oxidizing antiseptic. A 68- year-old female patient was admitted to our Emergency Department after ingestion of 3 tablets of 250 mg potassium permanganate as a suicide attempt. The physical exam revealed brown stained lesions in the oropharynx. Emergency endoscopy was performed by the gastroenterologist after the third hour of ingestion. Emergency endoscopy revealed multiple superficial (Grade I-II lesions on the esophagus and cardia, which were considered secondary to the caustic substance. The mainstay in the treatment of potassium permanganate is supportive and the immediate priority is to secure the airway. Emergency endoscopy is an important tool used to evaluate the location and severity of injury to the esophagus, stomach and duodenum after caustic ingestion. Patients with signs and symptoms of intentional ingestion should undergo endoscopy within 12 to 24 h to define the extent of the disease.

Potassium permanganate ingestion as a suicide attempt

Directory of Open Access Journals (Sweden)

Tuba Cimilli Ozturk

2012-01-01

Full Text Available Potassium permanganate is a highly corrosive, water-soluble oxidizing antiseptic. A 68- year-old female patient was admitted to our Emergency Department after ingestion of 3 tablets of 250 mg potassium permanganate as a suicide attempt. The physical exam revealed brown stained lesions in the oropharynx. Emergency endoscopy was performed by the gastroenterologist after the third hour of ingestion. Emergency endoscopy revealed multiple superficial (Grade I-II lesions on the esophagus and cardia, which were considered secondary to the caustic substance. The mainstay in the treatment of potassium permanganate is supportive and the immediate priority is to secure the airway. Emergency endoscopy is an important tool used to evaluate the location and severity of injury to the esophagus, stomach and duodenum after caustic ingestion. Patients with signs and symptoms of intentional ingestion should undergo endoscopy within 12 to 24 h to define the extent of the disease.

Acid-permanganate oxidation of potassium tetraphenylboron

International Nuclear Information System (INIS)

Smith, J.R.

1993-02-01

Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO 2 , highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO 4 /2.5M H 3 PO 4 solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO 2 (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation

Szilard-Chalmers Effect in Permanganate Solutions

Energy Technology Data Exchange (ETDEWEB)

Broda, E.

1944-07-01

This report was written by E. Broda at the Cavendish Laboratory (Cambridge) in January 1944 by Engelbert Broda and is about the Szilard-Chalmers effect in Permanganate Solutions. The Szilard-Chalmers effect in permanganate was studied in order to see what extent it is quantitative, or at least reproducible, in different conditions. The measurement description and results are discussed in this report. (nowak)

Effect of Rap1 binding on DNA distortion and potassium permanganate hypersensitivity.

Science.gov (United States)

Le Bihan, Yann-Vaï; Matot, Béatrice; Pietrement, Olivier; Giraud-Panis, Marie-Josèphe; Gasparini, Sylvaine; Le Cam, Eric; Gilson, Eric; Sclavi, Bianca; Miron, Simona; Le Du, Marie-Hélène

2013-03-01

Repressor activator protein 1 (Rap1) is an essential factor involved in transcription and telomere stability in the budding yeast Saccharomyces cerevisiae. Its interaction with DNA causes hypersensitivity to potassium permanganate, suggesting local DNA melting and/or distortion. In this study, various Rap1-DNA crystal forms were obtained using specifically designed crystal screens. Analysis of the DNA conformation showed that its distortion was not sufficient to explain the permanganate reactivity. However, anomalous data collected at the Mn edge using a Rap1-DNA crystal soaked in potassium permanganate solution indicated that the DNA conformation in the crystal was compatible with interaction with permanganate ions. Sequence-conservation analysis revealed that double-Myb-containing Rap1 proteins all carry a fully conserved Arg580 at a position that may favour interaction with permanganate ions, although it is not involved in the hypersensitive cytosine distortion. Permanganate reactivity assays with wild-type Rap1 and the Rap1[R580A] mutant demonstrated that Arg580 is essential for hypersensitivity. AFM experiments showed that wild-type Rap1 and the Rap1[R580A] mutant interact with DNA over 16 successive binding sites, leading to local DNA stiffening but not to accumulation of the observed local distortion. Therefore, Rap1 may cause permanganate hypersensitivity of DNA by forming a pocket between the reactive cytosine and Arg580, driving the permanganate ion towards the C5-C6 bond of the cytosine.

A long-term bench-scale investigation of permanganate consumption by aquifer materials.

Science.gov (United States)

Xu, Xiuyuan; Thomson, Neil R

2009-11-20

In situ chemical oxidation (ISCO) applications using permanganate involve the injection or release of permanganate into the subsurface to destroy various target contaminants. Naturally occurring reduced components associated with aquifer materials can exert a significant oxidant demand thereby reducing the amount of permanganate available for the destruction of contaminants as well as reducing the overall rate of oxidation. Quantification of this natural oxidant demand (NOD) is a requirement for site-specific assessment and the design of cost-effective oxidant delivery systems. To further our understanding of the interaction between permanganate and aquifer materials, aerobic and anaerobic aquifer materials from eight representative sites throughout North America were tested in a series of systematic bench-scale experiments. Various permanganate to aquifer solids mass loading ratios at different initial permanganate concentrations in well-mixed batch reactors were monitored for >300 days. All NOD temporal profiles demonstrated an initial fast consumption rate followed by a persistent slower consumption rate. The data generated show that the mass loading ratio, the initial permanganate concentration, and the nature and quantity of reduced aquifer material species are the main factors controlling permanganate consumption rates. A higher initial permanganate concentration or a larger mass loading ratio produced a larger fast NOD consumption rate and generated a corresponding higher maximum NOD value. Hence, both the NOD temporal profile and the maximum NOD are not single-valued but are heavily dependent on the experimental conditions. Predictive relationships were developed to estimate the maximum NOD and the NOD at 7 days based on aquifer material properties. The concentration of manganese oxides deposited on the aquifer solids was highly correlated with the mass of permanganate consumed suggesting that passivation of NOD reaction sites occurred due to the formation

Ruthenium nanoparticles supported on CeO2 for catalytic permanganate oxidation of butylparaben.

Science.gov (United States)

Zhang, Jing; Sun, Bo; Guan, Xiaohong; Wang, Hui; Bao, Hongliang; Huang, Yuying; Qiao, Junlian; Zhou, Gongming

2013-11-19

This study developed a heterogeneous catalytic permanganate oxidation system with ceria supported ruthenium, Ru/CeO2 (0.8‰ as Ru), as catalyst for the first time. The catalytic performance of Ru/CeO2 toward butylparaben (BP) oxidation by permanganate was strongly dependent on its dosage, pH, permanganate concentration and temperature. The presence of 1.0 g L(-1) Ru/CeO2 increased the oxidation rate of BP by permanganate at pH 4.0-8.0 by 3-96 times. The increase in Ru/CeO2 dosage led to a progressive enhancement in the oxidation rate of BP by permanganate at neutral pH. The XANES analysis revealed that (1) Ru was deposited on the surface of CeO2 as Ru(III); (2) Ru(III) was oxidized by permanganate to its higher oxidation state Ru(VI) and Ru(VII), which acted as the co-oxidants in BP oxidation; (3) Ru(VI) and Ru(VII) were reduced by BP to its initial state of Ru(III). Therefore, Ru/CeO2 acted as an electron shuttle in catalytic permanganate oxidation process. LC-MS/MS analysis implied that BP was initially attacked by permanganate or Ru(VI) and Ru(VII) at the aromatic ring, leading to the formation of various hydroxyl-substituted and ring-opening products. Ru/CeO2 could maintain its catalytic activity during the six successive runs. In conclusion, catalyzing permanganate oxidation with Ru/CeO2 is a promising technology for degrading phenolic pollutants in water treatment.

Chemically and compositionally modified solid solution disordered multiphase nickel hydroxide positive electrode for alkaline rechargeable electrochemical cells

Science.gov (United States)

Ovshinsky, Stanford R.; Corrigan, Dennis; Venkatesan, Srini; Young, Rosa; Fierro, Christian; Fetcenko, Michael A.

1994-01-01

A high capacity, long cycle life positive electrode for use in an alkaline rechargeable electrochemical cell comprising: a solid solution nickel hydroxide material having a multiphase structure that comprises at least one polycrystalline .gamma.-phase including a polycrystalline .gamma.-phase unit cell comprising spacedly disposed plates with at least one chemical modifier incorporated around the plates, the plates having a range of stable intersheet distances corresponding to a 2.sup.+ oxidation state and a 3.5.sup.+, or greater, oxidation state; and at least one compositional modifier incorporated into the solid solution nickel hydroxide material to promote the multiphase structure.

Using slow-release permanganate candles to remediate PAH-contaminated water

International Nuclear Information System (INIS)

Rauscher, Lindy; Sakulthaew, Chainarong; Comfort, Steve

2012-01-01

Highlights: ► We quantified the efficacy of slow-release permanganate-paraffin candles to degrade and mineralize PAHs. ► 14 C-labeled PAHs were used to quantify both adsorption and transformation. ► Permanganate-treated PAHs were more biodegradable in soil microcosms. ► A flow-through candle system was used to quantify PAH removal in urban runoff. - Abstract: Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin–KMnO 4 ) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results showed most of the 16 PAHs tested were degraded within 2–4 h. Using 14 C-labled phenanthrene and benzo(a)pyrene, we demonstrated that the wax matrix of the candle initially adsorbs the PAH, but then releases the PAH back into solution as transformed, more water soluble products. While permanganate was unable to mineralize the PAHs (i.e., convert to CO 2 ), we found that the permanganate-treated PAHs were much more biodegradable in soil microcosms. To test the concept of using candles to treat PAHs in multiple runoff events, we used a flow-through system where urban runoff water was pumped over a miniature candle in repetitive wet–dry, 24-h cycles. Results showed that the candle was robust in removing PAHs by repeatedly releasing permanganate and degrading the PAHs. These results provide proof-of-concept that permanganate candles could potentially provide a low-cost, low-maintenance approach to

Using slow-release permanganate candles to remediate PAH-contaminated water

Energy Technology Data Exchange (ETDEWEB)

Rauscher, Lindy, E-mail: purplerauscher@neb.rr.com [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Sakulthaew, Chainarong, E-mail: chainarong@huskers.unl.edu [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Department of Veterinary Technology, Kasetsart University, Bangkok 10900 (Thailand); Comfort, Steve, E-mail: scomfort1@unl.edu [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States)

2012-11-30

Highlights: Black-Right-Pointing-Pointer We quantified the efficacy of slow-release permanganate-paraffin candles to degrade and mineralize PAHs. Black-Right-Pointing-Pointer {sup 14}C-labeled PAHs were used to quantify both adsorption and transformation. Black-Right-Pointing-Pointer Permanganate-treated PAHs were more biodegradable in soil microcosms. Black-Right-Pointing-Pointer A flow-through candle system was used to quantify PAH removal in urban runoff. - Abstract: Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin-KMnO{sub 4}) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results showed most of the 16 PAHs tested were degraded within 2-4 h. Using {sup 14}C-labled phenanthrene and benzo(a)pyrene, we demonstrated that the wax matrix of the candle initially adsorbs the PAH, but then releases the PAH back into solution as transformed, more water soluble products. While permanganate was unable to mineralize the PAHs (i.e., convert to CO{sub 2}), we found that the permanganate-treated PAHs were much more biodegradable in soil microcosms. To test the concept of using candles to treat PAHs in multiple runoff events, we used a flow-through system where urban runoff water was pumped over a miniature candle in repetitive wet-dry, 24-h cycles. Results showed that the candle was robust in removing PAHs by repeatedly releasing permanganate and degrading the PAHs. These results provide

Oxidation kinetics of crystal violet by potassium permanganate in acidic medium

Science.gov (United States)

Khan, Sameera Razi; Ashfaq, Maria; Mubashir; Masood, Summyia

2016-05-01

The oxidation kinetics of crystal violet (a triphenylmethane dye) by potassium permanganate was focused in an acidic medium by the spectrophotometric method at 584 nm. The oxidation reaction of crystal violet by potassium permanganate is carried out in an acidic medium at different temperatures ranging within 298-318 K. The kinetic study was carried out to investigate the effect of the concentration, ionic strength and temperature. The reaction followed first order kinetics with respect to potassium permanganate and crystal violet and the overall rate of the reaction was found to be second order. Thermodynamic activation parameters like the activation energy ( E a), enthalpy change (Δ H*), free energy change (Δ G*), and entropy change (Δ S*) have also been evaluated.

Potassium Permanganate Poisoning: A Nonfatal Outcome

Directory of Open Access Journals (Sweden)

Suzan M. Eteiwi

2015-07-01

Full Text Available Acute poisoning by potassium permanganate is a rare condition with high morbidity and mortality. Diagnosis of the condition relies on a history of exposure or ingestion and a high degree of clinical suspicion. Oxygen desaturation and the presence of methemoglobin are also helpful indicators. Since no specific antidote is available, treatment is mainly supportive. Few cases have been reported in the literature following potassium permanganate ingestion, whether intentional or accidental, and most of the patients in these cases had unfavorable outcomes, which was not the case in our patient. Our patient, a 73-year-old male, purchased potassium permanganate over the counter mistaking it for magnesium salt, which he frequently used as a laxative. Several hours after he ingested it, he was admitted to the endocrine department at King Hussein Medical Center, Jordan, with acute rapidly evolving shortness of breath. During hospitalization, his liver function tests deteriorated. Since he was diagnosed early and managed promptly he had a favorable outcome.

Investigation of electrochemical synthesis of ferrate, Part I: Electrochemical behavior of iron and its several alloys in concentrated alkaline solutions

Directory of Open Access Journals (Sweden)

Čekerevac Milan I.

2009-01-01

Full Text Available In recent years, considerable attention has been paid to various applications of Fe(VI due to its unique properties such as oxidizing power, selective reactivity, stability of the salt, and non-toxic decomposition by-products of ferric ion. In environmental remediation processes, Fe(VI has been proposed as green oxidant, coagulant, disinfectant, and antifoulant. Therefore, it is considered as a promising multi-purpose water treatment chemical. Fe(VI has also potential applications in electrochemical energy source, as 'green cathode'. The effectiveness of ferrate as a powerful oxidant in the entire pH range, and its use in environmental applications for the removal of wide range of contaminants has been well documented by several researchers. There is scientific evidence that ferrate can effectively remove arsenic, algae, viruses, pharmaceutical waste, and other toxic heavy metals. Although Fe(VI was first discovered in early eighteen century, detailed studies on physical and chemical properties of Fe(VI had to wait until efficient synthetic and analytical methods of Fe(VI were developed by Schreyer et al. in the 1950s. Actually, there have been developed three ways for the preparation of Fe(VI compounds : the wet oxidation of Fe(II and Fe(III compounds, the dry oxidation of the same, and the electrochemistry method, mainly based on the trans passive oxidation of iron. High purity ferrates Fe(VI can be generated when electrode of the pure iron metal or its alloys are anodized in concentrated alkaline solution. It is known that the efficiency of electrochemical process of Fe(VI production depends on many factors such as current density, composition of anode material, types of electrolyte etc. In this paper, the electrochemical synthesis of ferrate(VI solution by the anodic dissolution of iron and its alloys in concentrated water solution of NaOH and KOH is investigated. The process of transpassive dissolution of iron to ferrate(VI was studied by

Oxidation of non-steroidal anti-inflammatory drugs with aqueous permanganate.

Science.gov (United States)

Rodríguez-Álvarez, Tania; Rodil, Rosario; Quintana, José Benito; Triñanes, Sara; Cela, Rafael

2013-06-01

Potassium permanganate is a strong oxidant widely used in drinking water treatment, that can react with organic micropollutants. Thus, the oxidation kinetics and transformation route of seven non-steroidal anti-inflammatory drugs (NSAIDs) upon reaction with potassium permanganate was investigated. A liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) system was used to follow the time course of pharmaceuticals concentrations and for the identification of their by-products. Under strong oxidation conditions (2 mg L(-1) KMnO4, 24 h), only two NSAIDs were significantly degraded: indomethacine and diclofenac. The degradation kinetics of these two drugs was investigated at different concentrations of permanganate, chlorides, phosphates and sample pH by means of a full factorial experimental design. Depending on these factors, half-lives were in the range: 2-270 h for indomethacine and 3-558 h for diclofenac, equivalent to apparent second order constants between 0.65 and 9.5 M(-1) s(-1) and 0.27 and 7.4 M(-1) s(-1), respectively. Permanganate concentration was the most significant factor on NSAIDs oxidation kinetics, but the pH also played a significant role in diclofenac reaction, being faster at acidic pH. In the case of indomethacine, the dose of permanganate seemed also to play an autocatalytic effect. The use of an accurate-mass high resolution LC-Q-TOF-MS system permitted the identification of a total of 13 by-products. The transformation path of these drugs consisted mainly of hydroxylations, decarboxylations and oxidation of aromatic double bonds, with ring opening. The software predicted toxicity of these products indicates that they are expected not to be more toxic than the NSAIDs, with the exception of two indomethacine by-products. Reaction in real samples was slower and/or incomplete for both pharmaceuticals, depending on the organic matter content of the sample. However, still all transformation products could be detected for

Effect of decontamination on oxidation of austenitic stainless steel in reactor conditions

International Nuclear Information System (INIS)

Starkman, T.

1984-07-01

Austenitic stainless steels were oxidized in static autoclaves in light water reactor conditions. After the autoclave treatments the specimens were decontaminated with the aid of alkaline potassium permanganate (AP) and oxalic and citric acid (CITROX) as well as electrochemically in H 3 PO 4 . Alternating oxidation and decontamination tests were performed. An elemental analysis of the surfaces of the specimens was carried out by electron spectroscopy. Changes in structures and thicknesses of the oxide layers were observed. (author)

Potassium permanganate poisoning--a rare cause of fatal self poisoning.

OpenAIRE

Ong, K L; Tan, T H; Cheung, W L

1997-01-01

Attempted suicide by self poisoning is common because of the ready availability of drugs, whether prescribed or bought over the counter. In some cases, the ingestion of seemingly innocuous household products or chemicals can result in death. Potassium permanganate is an example. Poisoning with potassium permanganate can be fatal when a significant amount is ingested, as shown by a patient who suffered both the corrosive and systemic toxic effects of this chemical.

Microwave- and Ultrasound-Accelerated Green Permanganate Oxidation of Thioethers

DEFF Research Database (Denmark)

Luu, Thi Xuan Thi; Le, Huu Tan; Le, Thach Ngoc

2015-01-01

Product formation from the solvent-free oxidation of aliphatic, cyclic or aromatic thioethers by permanganate supported on copper sulfate pentahydrate has been investigated in detail with respect to the importance of the nature of thioethers, the molar ratio of potassium permanganate absorbed...

Oxidative desulfurization of Cayirhan lignites by permanganate solution

Energy Technology Data Exchange (ETDEWEB)

Guru, M.; Tuzun, F.N.; Murathan, A.S.; Asan, A.; Kiyak, T. [Gazi University, Ankara (Turkey). Dept. for Chemical Engineering

2008-07-01

Unless important developments record new and renewable energy sources, the role of fossil fuels as an energy resource goes on. It is possible to detect sulfur, heavy metals, and tracer elements such as arsenic and selenium by decreasing calorific value of coals. Sulfur oxides, which are the main pollutants in atmosphere, are irritative to humans and plants, and erosion occurs on buildings. Although there are high lignite reservoirs, high sulfur content limits the efficient use of them. In this research, it is aimed to convert combustible sulfur in coal to non-combustible sulfur form in the ash by oxidizing it with permanganate solution. During this research, the effect of two different parameters of potassium permanganate concentration, processing time, and mean particle size were investigated at constant room temperature and shaking rate. The conversion of combustible sulfur to non-combustible sulfur form was achieved optimally with 0.14 M potassium permanganate solution, 0.1 mm mean particle size at 16 h of treatment time, and the combustible sulfur amount was decreased by 46.37% compared to undoped conditions.

Role of ligands in permanganate oxidation of organics.

Science.gov (United States)

Jiang, Jin; Pang, Su-Yan; Ma, Jun

2010-06-01

We previously demonstrated that several ligands such as phosphate, pyrophosphate, EDTA, and humic acid could significantly enhance permanganate oxidation of triclosan (one phenolic biocide), which was explained by the contribution of ligand-stabilized reactive manganese intermediates in situ formed upon permanganate reduction. To further understand the underlying mechanism, we comparatively investigated the influence of ligands on permanganate oxidation of bisphenol A (BPA, one phenolic endocrine-disrupting chemical), carbamazepine (CBZ, a pharmaceutical containing the olefinic group), and methyl p-tolyl sulfoxide (TMSO, a typical oxygen-atom acceptor). Selected ligands exerted oxidation enhancement for BPA but had negligible influence for CBZ and TMSO. This was mainly attributed to the effects of identified Mn(III) complexes, which would otherwise disproportionate spontaneously in the absence of ligands. The one-electron oxidant Mn(III) species exhibited no reactivity toward CBZ and TMSO for which the two-electron oxygen donation may be the primary oxidation mechanism but readily oxidized BPA. The latter case was a function of pH, the complexing ligand, and the molar [Mn(III)]:[ligand] ratio, generally consistent with the patterns of ligand-affected permanganate oxidation. Moreover, the combination of the one-electron reduction of Mn(III) (Mn(III) + e(-) -->Mn(II)) and the Mn(VII)/Mn(II) reaction in excess ligands (Mn(VII) + 4Mn(II) ----> (ligands) 5Mn(III)) suggested a catalytic role of the Mn(III)/Mn(II) pair in permanganate oxidation of some phenolics in the presence of ligands.

Time dependence of the natural passivation process on AISI 304 in an alkaline medium: Atomic force microscopy and scanning Kelvin probe force microscopy as additional tools to electrochemical impedance spectroscopy

Science.gov (United States)

Benaioun, N. E.; Maafa, I.; Florentin, A.; Denys, E.; Hakiki, N. E.; Moulayat, N.; Bubendorff, J. L.

2018-04-01

Thin surface films formed on AISI 304 samples in an alkaline solution of pH = 13 are studied by atomic force microscopy (AFM), scanning Kelvin probe force microscopy (SKPFM) and electrochemical impedance spectroscopy (EIS) as a function of immersion time. The results reveal that changes on EIS diagrams correspond to topographical modifications on the sample surface as shown by AFM. Both techniques are therefore complementary. The oxide layer is chemically homogenous as shown by SKPFM imaging and our ultra-thin passive layer is an efficient barrier against corrosion.

Using slow-release permanganate candles to remediate PAH-contaminated water.

Science.gov (United States)

Rauscher, Lindy; Sakulthaew, Chainarong; Comfort, Steve

2012-11-30

Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin-KMnO(4)) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs. Our objective was to determine if slow-release permanganate candles could be used to degrade and mineralize PAHs. Batch experiments quantified PAH degradation rates in the presence of the oxidant candles. Results showed most of the 16 PAHs tested were degraded within 2-4 h. Using (14)C-labled phenanthrene and benzo(a)pyrene, we demonstrated that the wax matrix of the candle initially adsorbs the PAH, but then releases the PAH back into solution as transformed, more water soluble products. While permanganate was unable to mineralize the PAHs (i.e., convert to CO(2)), we found that the permanganate-treated PAHs were much more biodegradable in soil microcosms. To test the concept of using candles to treat PAHs in multiple runoff events, we used a flow-through system where urban runoff water was pumped over a miniature candle in repetitive wet-dry, 24-h cycles. Results showed that the candle was robust in removing PAHs by repeatedly releasing permanganate and degrading the PAHs. These results provide proof-of-concept that permanganate candles could potentially provide a low-cost, low-maintenance approach to remediating PAH-contaminated water. Copyright © 2012 Elsevier B.V. All rights reserved.

Thermodynamic and electrochemical study on the mechanism of formation of Ag(OH)4− in alkaline media

International Nuclear Information System (INIS)

Zamora-Garcia, I.R.; Alatorre-Ordaz, A.; Ibanez, J.G.; Garcia-Jimenez, M.G.; Nosaka, Y.; Kobayashi, T.; Sugita, S.

2013-01-01

Highlights: • Sensitive electrochemical techniques were used to evidence the formation of Ag(III). • The required potential for the generation of Ag(III) was found by using UV–vis to monitor species being formed. • A mechanism for the production of Ag(III) in the form of Ag(OH) 4 − is proposed. -- Abstract: A mechanism based on electrochemical, spectrophotometric and scanning electron microscopy (SEM) data in alkaline media is proposed for the generation of Ag(III) in the form of Ag(OH) 4 − . The formation of Ag(III) from Ag 0 is a rather complex multistep process that involves several steps. The presence of soluble Ag(I) species as Ag(OH) 2 − is of paramount importance for the production of soluble Ag(OH) 4 − , whose decomposition time is shown to exceed 8 h

Crystal structures and thermal decomposition of permanganates AE[MnO{sub 4}]{sub 2} . n H{sub 2}O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

Energy Technology Data Exchange (ETDEWEB)

Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

2017-10-01

Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O and Ba[MnO{sub 4}]{sub 2} are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO{sub 4}]{sub 2} a long time ago, we employed a cation-exchange column loaded with Ba{sup 2+} cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O exhibiting [CaO{sub 8}] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O with [SrO{sub 10}] polyhedra adopts the cubic space group P2{sub 1}3 with a=964.19(7) pm and Z=4. So the harder the AE{sup 2+} cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO{sub 4}]{sub 2} in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO{sub 12}] polyhedra. During the thermal decomposition of Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H{sub 2}O molecule at 157 C. The crystal structure of Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn{sub 2}O{sub 3} and the oxomanganates(III,IV) AEMn{sub 3}O{sub 6} (AE=Ca and Sr) remain as final decomposition products at 800 C

Removal of emerging pollutants by Ru/TiO2-catalyzed permanganate oxidation.

Science.gov (United States)

Zhang, Jing; Sun, Bo; Xiong, Xinmei; Gao, Naiyun; Song, Weihua; Du, Erdeng; Guan, Xiaohong; Zhou, Gongming

2014-10-15

TiO2 supported ruthenium nanoparticles, Ru/TiO2 (0.94‰ as Ru), was synthesized to catalyze permanganate oxidation for degrading emerging pollutants (EPs) with diverse organic moieties. The presence of 1.0 g L(-1) Ru/TiO2 increased the second order reaction rate constants of bisphenol A, diclofenac, acetaminophen, sulfamethoxazole, benzotriazole, carbamazepine, butylparaben, diclofenac, ciprofloxacin and aniline at mg L(-1) level (5.0 μM) by permanganate oxidation at pH 7.0 by 0.3-119 times. The second order reaction rate constants of EPs with permanganate or Ru/TiO2-catalyzed permanganate oxidation obtained at EPs concentration of mg L(-1) level (5.0 μM) underestimated those obtained at EPs concentration of μg L(-1) level (0.050 μM). Ru/TiO2-catalyzed permanganate could decompose a mixture of nine EPs at μg L(-1) level efficiently and the second order rate constant for each EP was not decreased due to the competition of other EPs. The toxicity tests revealed that Ru/TiO2-catalyzed permanganate oxidation was effective not only for elimination of EPs but also for detoxification. The removal rates of sulfamethoxazole by Ru/TiO2-catalyzed permanganate oxidation in ten successive cycles remained almost constant in ultrapure water and slightly decreased in Songhua river water since the sixth run, indicating the satisfactory stability of Ru/TiO2. Ru/TiO2-catalyzed permanganate oxidation was selective and could remove selected EPs spiked in real waters more efficiently than chlorination. Therefore, Ru/TiO2-catalyzed permanganate oxidation is promising for removing EPs with electron-rich moieties. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study by acoustic emission and electrochemical methods of the corrosion and the protection of the copper-zinc alloy (60/40) in neutral and alkaline media

International Nuclear Information System (INIS)

Assouli, B.

2002-12-01

The aim of this work is to study and characterize, by electrochemical methods and acoustic emission, the corrosion and the protection of the copper-zinc alloy (60/40) having a metallographic structure αβ'. The electrochemical measurements, in neutral, chlorinated or alkaline medium have allowed, to study the corrosion resistance of the copper-zinc and to show that the corrosion of this alloy, in the used media, is determined by a diffusional mechanism. The observations to the optical and scanning electron microscopes and the EDX analyzes have confirmed that this corrosion phenomenon is mainly due to the selective dissolution of the β' phase. The acoustic emission has shown, during this corrosion, the presence of two emissive sources whose initiation has been attributed to the relaxation of the micro- and macro- residual stresses of the α phase. These stresses have been characterized by X-ray diffraction and the salvoes emitted during the relaxation of these stresses have been discriminated by the characteristic frequencies and by the barycenter of their spectral density. The protection of this alloy has been carried out by the 2-mercapto-benzimidazole (MBI). This last compound has been tested both as inhibitor added directly in the corrosive medium and/or as polymer film previously deposited by an electrochemical way (p-MBI). The MBI is very efficient for an inhibition in a chlorinated alkaline medium. It is an interphase inhibitor. The p-MBI is efficient too in a neutral chlorinated medium and is moreover non pollutant for the environment. (O.M.)

Studies on direct and indirect electrochemical immunoassays

OpenAIRE

Buckley, Eileen

1989-01-01

Two approaches to electrochemical immunoassay are reported. The first approach was an indirect method, involving an electroactive, enzyme-catalysed, substrate to product reaction. Conditions were optimised for the amperometric detection of para-aminophenol, the electroactive product of the alkaline phosphatase catalysed hydrolysis of a new substrate, p-aminophenylphosphate, after separation by HPLC. The second approach involved the direct electrochemical detection of an immunoglo...

Alkaline Leaching of Key, Non-Radioactive Components from Simulants and Hanford Tank Sludge 241-S-110: Results of FY01 Studies

Energy Technology Data Exchange (ETDEWEB)

Rapko, Brian M.; Vienna, John D.; Sinkov, Serguei I.; Kim, Jinseong; Cisar, Alan J.

2002-09-10

This study addressed three aspects in selected alkaline leaching: first, the use of oxidants persulfate, permanganate, and ferrate as selective chromium-leaching agents from washed Hanford Tank S-110 solids under varying conditions of hydroxide concentration, temperature, and time was investigated. Second, the selective dissolution of solids containing mercury(II) oxide under alkaline conditions was examined. Various compounds were studied for their effectiveness in dissolving mercury under varying conditions of time, temperature, and hydroxide concentration in the leachate. Three compounds were studied: cysteine, iodide, and diethyldithiophosphoric acid (DEDTPA). Finally, the possibility of whether an oxidant bound to an anion-exchange resin can be used to effectively oxidize chromium(III) in alkaline solutions was addressed. The experimental results remain ambiguous to date; further work is required to reach any definitive conclusions as to the effectiveness of this approach.

[Influence of pH on Kinetics of Anilines Oxidation by Permanganate].

Science.gov (United States)

Wang, Hui; Sun, Bo; Guan, Xiao-hong

2016-02-15

To investigate the effect of pH on the oxidation of anilines by potassium permanganate, aniline and p-Chloroaniline were taken as the target contaminants, and the experiments were conducted under the condition with potassium permanganate in excess over a wide pH range. The reaction displayed remarkable autocatalysis, which was presumably ascribed to the formation of complexes by the in situ generated MnOx and the target contaminants on its surface, and thereby improved the oxidation rate of the target contaminants by permanganate. The reaction kinetics was fitted with the pseudo-first-order kinetics at different pH to obtain the pseudo-first-order reaction constants (k(obs)). The second-order rate constants calculated from permanganate concentration and k,b, increased with the increase of pH and reached the maximum near their respective pKa, after which they decreased gradually. This tendency is called parabola-like shaped pH-rate profile. The second-order rate constants between permanganate and anilines were well fitted by the proton transfer model proposed by us in previous work.

Parabola-like shaped pH-rate profile for phenols oxidation by aqueous permanganate.

Science.gov (United States)

Du, Juanshan; Sun, Bo; Zhang, Jing; Guan, Xiaohong

2012-08-21

Oxidation of phenols by permanganate in the pH range of 5.0-9.0 generally exhibits a parabola-like shape with the maximum reaction rate obtained at pH close to phenols' pK(a). However, a monotonic increase or decrease is observed if phenols' pK(a) is beyond the pH range of 5.0-9.0. A proton transfer mechanism is proposed in which the undissociated phenol is directly oxidized by permanganate to generate products while a phenolate-permanganate adduct, intermediate, is formed between dissociated phenol and permanganate ion and this is the rate-limiting step for phenolates oxidation by permanganate. The intermediate combines with H(+) and then decomposes to products. Rate equations derived based on the steady-state approximation can well simulate the experimentally derived pH-rate profiles. Linear free energy relationships (LFERs) were established among the parameters obtained from the modeling, Hammett constants, and oxygen natural charges in phenols and phenolates. LFERs reveal that chlorine substituents have opposite influence on the susceptibility of phenols and phenolates to permanganate oxidation and phenolates are not necessarily more easily oxidized than their neutral counterparts. The chlorine substituents regulate the reaction rate of chlorophenolates with permanganate mainly by influencing the natural charges of the oxygen atoms of dissociated phenols while they influence the oxidation of undissociated chlorophenols by permanganate primarily by forming intramolecular hydrogen bonding with the phenolic group.

Two-phase titration of cerium(3) by permanganate

International Nuclear Information System (INIS)

Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

1986-01-01

Reaction of cerium (3) and permanganate was investigated at a room temperature depending on PH, concentrations of pyrophosphate, cerium (3), tetraphenylphosphonium and foreign compounds. Selective method of two-phase titration determination of cerium (3) by permanganate without using silver compounds, preliminary separation of chlorides, nitrates, was developed. The method was tested using alloys based on iron, nickel, REE, copper, cobalt (S r ≤0.008). Correctness is proved with method of standard additives

Potassium permanganate is not an effective pond disinfectant to control Dero digitata

Science.gov (United States)

Proliferative gill disease (PGD) is a major problem in cultured channel catfish, Ictalurus punctatus. This parasite requires Dero digitata to complete its life cycle. It is believed potassium permanganate disinfects ponds and reduces D. digitata populations, but this practice has not been verified...

Microbial Community Response of an Organohalide Respiring Enrichment Culture to Permanganate Oxidation

NARCIS (Netherlands)

Sutton, N.B.; Atashgahi, S.; Saccenti, E.; Grotenhuis, J.T.C.; Smidt, H.; Rijnaarts, H.H.M.

2015-01-01

While in situ chemical oxidation is often used to remediate tetrachloroethene (PCE) contaminated locations, very little is known about its influence on microbial composition and organohalide respiration (OHR) activity. Here, we investigate the impact of oxidation with permanganate on OHR rates, the

Influence of different nominal molecular weight fractions of humic acids on phenol oxidation by permanganate.

Science.gov (United States)

He, Di; Guan, Xiaohong; Ma, Jun; Yu, Min

2009-11-01

The effects of humic acid (HA) and its different nominal molecular weight (NMW) fractions on the phenol oxidation by permanganate were studied. Phenol oxidation by permanganate was enhanced by the presence of HA at pH 4-8, while slightly inhibited at pH 9-10. The effects of HA on phenol oxidation by permanganate were dependent on HA concentration and permanganate/phenol molar ratios. The high NMW fractions of HA enhanced phenol oxidation by permanganate at pH 7 more significantly than the low fractions of HA. The apparent second-order rate constants of phenol oxidation by permanganate in the presence of HA correlated well with their specific ultraviolet absorption (SUVA) at 254 nm and specific violet absorption (SVA) at 465 or 665 nm. High positive correlation coefficients (R(2) > 0.72) implied that pi-electrons of HA strongly influenced the reactivity of phenol towards permanganate oxidation which agreed well with the information provided by fluorescence spectroscopy. The FTIR analysis indicated that the HA fractions rich in aliphatic character, polysaccharide-like substances, and the amount of carboxylate groups had less effect on phenol oxidation by permanganate. The negative correlation between the rate constants of phenol oxidation by permanganate and O/C ratios suggested that the oxidation of phenol increased with a decrease in the content of oxygen-containing functional groups.

Study of niobium corrosion in alkaline medium

International Nuclear Information System (INIS)

Almeida, S.H. de.

1987-01-01

A comparative study of niobium electrochemical behaviour in NaOH and KOH solution, with concentrations between 0,5 and 6,1M is presented. The studies were done through electrochemicals assays, consisting in the corrosion potential and anodic and cathodic polarization curves, complemented by loss of mass experiments. The niobium anodic behaviour in alkaline medium is characterized by passivation occurrence, with a stable film formation. The Na oH solution in alkaline medium are more corrosible to niobium than the KOH solution. The loss of mass assays showed that the corrosion velocit is more dependente of hydroxide concentration in KOH medium than the NaOH medium. (C.G.C.) [pt

Beware of the Permanganate Volcano.

Science.gov (United States)

Snyder, Ellie

1980-01-01

Discusses hazards associated with the permanganate demonstration of volcanic eruptions. Alternate demonstrations are described, including the ammonium dichromate reaction, lava flow demonstration with baking soda and vinegar, and punk to illustrate air pollution from volcanic ash and cinders. (CS)

Effect of γ-exposure on retention of recoil 56Mn in permanganates

International Nuclear Information System (INIS)

Mishra, S.P.; Vijaya

2002-01-01

Full text: γ-exposure effect on recombination of recoil 56 Mn atom in La, Sr and Ba permanganates were studied with a special emphasis to pre-and post-activation γ-ray irradiation treatment using 60 Co source. Permanganates were inactivated by ionizing radiation as a function of γ-dose without neutron irradiation, however, pronounced effects were seen after neutron activation. Pre-irradiation increase the initial retention and promotes the annealing phenomenon as the introduction of defect into the lattice though on the other hand radiolytic phenomenon may also appear. Pre-activated sample gave higher retention value for lanthanum and barium permanganates in comparison to strontium permanganate at different γ-doses for desired period of gamma annealing than those obtained at corresponding γ-doses for similar length of time in case of post-activated targets. Kinetics of annealing by γ-radiolytic effects follow first order rate law. The observed results are discussed in the light of existing ideas for understanding the recoil stabilization phenomenon of parent reformation and the nature of precursors in permanganates

Nickel hydroxide positive electrode for alkaline rechargeable battery

Science.gov (United States)

Young, Kwo; Wang, Lixin; Mays, William; Reichman, Benjamin; Chao-Ian, Hu; Wong, Diana; Nei, Jean

2018-02-20

Certain nickel hydroxide active cathode materials for use in alkaline rechargeable batteries are capable of transferring >1.3 electrons per Ni atom under reversible electrochemical conditions. The specific capacity of the nickel hydroxide active materials is for example .gtoreq.325 mAh/g. The cathode active materials exhibit an additional discharge plateau near 0.8 V vs. a metal hydride (MH) anode. Ni in an oxidation state of less than 2, such as Ni.sup.1+, is able to participate in electrochemical reactions when using the present cathode active materials. It is possible that up to 2.3 electrons, up to 2.5 electrons or more may be transferred per Ni atom under electrochemical conditions.

Nickel hydroxide positive electrode for alkaline rechargeable battery

Science.gov (United States)

Young, Kwo; Wang, Lixin; Mays, William; Reichman, Benjamin; Chao-Ian, Hu; Wong, Diana; Nei, Jean

2018-04-03

Certain nickel hydroxide active cathode materials for use in alkaline rechargeable batteries are capable of transferring >1.3 electrons per Ni atom under reversible electrochemical conditions. The specific capacity of the nickel hydroxide active materials is for example .gtoreq.325 mAh/g. The cathode active materials exhibit an additional discharge plateau near 0.8 V vs. a metal hydride (MH) anode. Ni in an oxidation state of less than 2, such as Ni.sup.1+, is able to participate in electrochemical reactions when using the present cathode active materials. It is possible that up to 2.3 electrons, up to 2.5 electrons or more may be transferred per Ni atom under electrochemical conditions.

Control of manganese dioxide particles resulting from in situ chemical oxidation using permanganate.

Science.gov (United States)

Crimi, Michelle; Ko, Saebom

2009-02-01

In situ chemical oxidation using permanganate is an approach to organic contaminant site remediation. Manganese dioxide particles are products of permanganate reactions. These particles have the potential to deposit in the subsurface and impact the flow-regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport and contact between the oxidant and contaminants of concern. The goals of this research were to determine if MnO(2) can be stabilized/controlled in an aqueous phase, and to determine the dependence of particle stabilization on groundwater characteristics. Bench-scale experiments were conducted to study the ability of four stabilization aids (sodium hexametaphosphate (HMP), Dowfax 8390, xanthan gum, and gum arabic) in maintaining particles suspended in solution under varied reaction conditions and time. Variations included particle and stabilization aid concentrations, ionic content, and pH. HMP demonstrated the most promising results, as compared to xanthan gum, gum arabic, and Dowfax 8390 based on results of spectrophotometric studies of particle behavior, particle filtration, and optical measurements of particle size and zeta potential. HMP inhibited particle settling, provided for greater particle stability, and resulted in particles of a smaller average size over the range of experimental conditions evaluated compared to results for systems that did not include HMP. Additionally, HMP did not react unfavorably with permanganate. These results indicate that the inclusion of HMP in a permanganate oxidation system improves conditions that may facilitate particle transport.

Corrosion of cupronickel alloy in permanganate under acidic condition

International Nuclear Information System (INIS)

Subramanian, Veena; Chandramohan, P.; Srinivasan, M.P.; Velmurugan, S.; Narasimhan, S.V.

2007-01-01

Cupronickel alloys are used as heat exchanger tube materials in nuclear power plant auxiliary coolant systems. In this work, the corrosion behaviour of cupronickel (70:30) alloy in permanganic acid medium was studied. Corrosion rate was found to follow logarithmic kinetics. Cyclic polarization studies showed that cupronickel did not undergo pitting in permanganic acid medium but uniform corrosion was observed. Presence of 0.43 mol/m 3 chromate in 2.5 mol/m 3 permanganic acid was found to decrease the corrosion rate of cupronickel by 50%. EIS and XPS studies revealed that the film formed on cupronickel was protective in nature and contained oxides of copper, nickel and manganese (mainly MnOOH). The composition of the film on cupronickel that had undergone chromate treatment also showed similar film except that it contained some chromium (III)

Evaluating Effects from Contacting Superlig(R) 644 Resin with Sodium Permanganate

International Nuclear Information System (INIS)

Crooks, W.J. III

2002-01-01

This work simulates the inadvertent transfer of 1M sodium permanganate solution into the lead cesium ion exchange column containing SuperLig(R) 644 resin. The effects of contacting 1 molar sodium permanganate with SuperLig(R) 644 are characterized using the Advanced Reactive System Screening Tool

Potassium permanganate cleansing is an effective sanitary method for the reduction of bacterial bioload on raw Coriandrum sativum.

Science.gov (United States)

Subramanya, Supram Hosuru; Pai, Vasudha; Bairy, Indira; Nayak, Niranjan; Gokhale, Shishir; Sathian, Brijesh

2018-02-13

Raw vegetables including flowers, leaves, stems, and roots are important carriers of food borne pathogens. We evaluated the bacteriological contamination of unwashed coriander leaves, and effectiveness of cleansing with 0.1% potassium permanganate solution as decontamination method. Significant bacterial contamination including pathogens like Salmonella species and Aeromonas species were isolated from unwashed coriander leaves. Decontamination with 0.1% potassium permanganate was found to be more effective than three steps wash with sterile water.

N-nitrosodimethylamine (NDMA) as a product of potassium permanganate reaction with aqueous solutions of dimethylamine (DMA).

Science.gov (United States)

Andrzejewski, Przemysław; Nawrocki, Jacek

2009-03-01

The reactivity of permanganate with dimethylamine, as possible path of NDMA formation, has been investigated. The results have shown that potassium permanganate reaction with aqueous solutions of dimethylamine (DMA) leads to the formation of N-nitrosodimethylamine (NDMA). The contact time, the molar ratio of permanganate and DMA, pH and presence of nitrite are the key factors influencing the efficiency of NDMA formation. Significant conversion rates of DMA to NDMA were observed only for the high doses of permanganate, which were many times higher than those typically used in water treatment. This reaction however is of importance for water treatment technology, since it shows the possibility of NDMA formation as a result of oxidation of DMA. It is likely that nitrosation is the main path of the reaction. An important role of MnO2 suspension, formed as a result of permanganate reduction in NDMA formation is emphasized. Significant influence of MnO2 suspension on NDMA formation should draw our attention to the potential impact of MnO2 activated filtration beds on NDMA formation.

Potassium permanganate for mercury vapor environmental control

Science.gov (United States)

Kuivinen, D. E.

1972-01-01

Potassium permanganate (KMnO4) was evaluated for application in removing mercury vapor from exhaust air systems. The KMnO4 may be used in water solution with a liquid spray scrubber system or as a solid adsorber bed material when impregnated onto a zeolite. Air samples contaminated with as much as 112 mg/cu m of mercury were scrubbed to 0.06mg/cum with the KMnO4-impregnated zeolite (molecular sieve material). The water spray solution of permanganate was also found to be as effective as the impregnated zeolite. The KMnO4-impregnated zeolite was applied as a solid adsorber material to (1) a hardware decontamination system, (2) a model incinerator, and (3) a high vacuum chamber for ion engine testing with mercury as the propellant. A liquid scrubber system was also applied in an incinerator system. Based on the results of these experiments, it is concluded that the use of KMnO4 can be an effective method for controlling noxious mercury vapor.

Anditalea andensis ANESC-ST--An Alkaliphilic Halotolerant Bacterium Capable of Electricity Generation under Alkaline-Saline Conditions.

Directory of Open Access Journals (Sweden)

Wei Shi

Full Text Available A great challenge in wastewater bioremediation is the sustained activity of viable microorganisms, which can contribute to the breakdown of waste contaminants, especially in alkaline pH conditions. Identification of extremophiles with bioremediation capability can improve the efficiency of wastewater treatment. Here, we report the discovery of an electrochemically active alkaliphilic halotolerant bacterium, Anditalea andensis ANESC-ST (=CICC10485T=NCCB 100412T, which is capable of generating bioelectricity in alkaline-saline conditions. A. andensis ANESC-ST was shown to grow in alkaline conditions between pH 7.0-11.0 and also under high salt condition (up to 4 wt% NaCl. Electrical output was further demonstrated in microbial fuel cells (MFCs with an average current density of ~0.5 µA/cm2, even under the harsh condition of 4 wt% NaCl and pH 9.0. Subsequent introduction of secreted extracellular metabolites into MFCs inoculated with Escherichia coli or Pseudomonas aeruginosa yielded enhanced electrical output. The ability of A. andensis ANESC-ST to generate energy under alkaline-saline conditions points towards a solution for bioelectricity recovery from alkaline-saline wastewater. This is the first report of A.andensis ANESC-ST producing bioelectricity at high salt concentration and pH.

Extracting silica from rice husk treated with potassium permanganate

International Nuclear Information System (INIS)

Javed, S.H.; Naveed, S.

2008-01-01

As an agro-waste material the rice husk is abundantly available is rice growing areas. In many areas rice husk after burning involves disposal problems because of higher quantities of silica present in it. Rice husk contains about 20 per cent silica, which is present in hydrated amorphous form. On thermal treatment the silica converts into crystobalite, which is a crystalline form of silica. However amorphous silica can be produced under controlled conditions ensuring high reactivity and large surface area. Leaching the rice husk with organic acids and alkalies removes the metallic impurities from its surface. How a dilute solution of potassium permanganate affects the rice husk is the subject of this research paper. The rice husk was treated with the dilute solution of potassium permanganate at room temperature and then analyzed by SEM, TGA and the ash by analytical treatment after burning under controlled temperature. The SEM results revealed that the protuberances of the rice husk were eaten away by the solution of potassium permanganate. Pyrolysis of rice husks showed that the thermal degradation of the treated rice husk was faster than the untreated rice husk where as analytical results confirmed the presence of more amorphous silica than untreated rice husk. (author)

Status of potassium permanganate - 2008

Science.gov (United States)

This is a brief overview of the Technical Sections completed and being worked on for the New Animal Drug Application (NADA) for potassium permanganate will be presented. Initial Label Claim (Columnaris on catfish/HSB): 1) Human Food Safety - Complete for all fin fish (June 1999). A hazard charac...

Electrochemical alkaline Fe(VI) water purification and remediation.

Science.gov (United States)

Licht, Stuart; Yu, Xingwen

2005-10-15

Fe(VI) is an unusual and strongly oxidizing form of iron, which provides a potentially less hazardous water-purifying agent than chlorine. A novel on-line electrochemical Fe(VI) water purification methodology is introduced. Fe(VI) addition had been a barrier to its effective use in water remediation, because solid Fe(VI) salts require complex (costly) syntheses steps and solutions of Fe(VI) decompose. Online electrochemical Fe(VI) water purification avoids these limitations, in which Fe(VI) is directly prepared in solution from an iron anode as the FeO42- ion, and is added to the contaminant stream. Added FeO42- decomposes, by oxidizing a wide range of water contaminants including sulfides (demonstrated in this study) and other sulfur-containing compounds, cyanides (demonstrated in this study), arsenic (demonstrated in this study), ammonia and other nitrogen-containing compounds (previously demonstrated), a wide range of organics (phenol demonstrated in this study), algae, and viruses (each previously demonstrated).

Solid-phase electrochemical reduction of graphene oxide films in alkaline solution

Science.gov (United States)

Basirun, Wan J.; Sookhakian, Mehran; Baradaran, Saeid; Mahmoudian, Mohammad R.; Ebadi, Mehdi

2013-09-01

Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO.

Oxidative dissolution of chromium from Hanford tank sludges under alkaline conditions

International Nuclear Information System (INIS)

Rapko, B.M.; Delegard, C.H.; Wagner, M.J.

1997-08-01

Alkaline oxidative leaching has been performed on caustic leached sludges from the three following Hanford waste tanks: BY-110, S-107, and SX-108. These samples were chosen because they represent types of waste where significant amounts of Cr are located and show relatively poor dissolution of Cr during standard caustic leaching. The experiments involved tests with three chemical oxidants, permanganate, ozone and oxygen, and a blank, argon. The effects of varying the hydroxide concentration of the leachate (from 0.1 M to 3 M) and of time and temperature (from room temperature to 80 degrees C) were also examined

75 FR 65448 - Potassium Permanganate From the People's Republic of China: Continuation of Antidumping Duty Order

Science.gov (United States)

2010-10-25

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-001] Potassium Permanganate From... Trade Commission (``ITC'') that revocation of the antidumping duty order on potassium permanganate from... order on potassium permanganate from the PRC pursuant to section 751(c) of the Tariff Act of 1930, as...

75 FR 52509 - Potassium Permanganate from the People's Republic of China: Final Results of Expedited Sunset...

Science.gov (United States)

2010-08-26

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-001] Potassium Permanganate from...'') initiated a sunset review of the antidumping duty order on potassium permanganate from the People's Republic... antidumping duty order on potassium permanganate from the PRC pursuant to section 751(c) of the Tariff Act of...

"Too good to be true": the controversy over the use of permanganate of potash as an antidote to snake poison and the circulation of Brazilian physiology in the nineteenth century.

Science.gov (United States)

Vimieiro Gomes, Ana Carolina

2012-01-01

This article examines an international controversy over the most visible scientific event of Brazilian physiology in the nineteenth century. In 1881, Brazilian scientist João Baptista Lacerda stated that he had found an efficient antidote to the poison of Brazilian snakes: permanganate of potash (nowadays, potassium permanganate). His findings were given great publicity in Brazil and traveled rapidly around the world. Scientists, especially in France, contradicted Lacerda's claims. They argued that permanganate of potash could not be a genuine antidote to snake bites since it could not neutralize snake venom when diffused in the body. Lacerda turned down such criticism, claiming that clinical observation provided solid evidence for the drug's local action, on the spot surrounding the bite. The controversy over the use of permanganate of potash as an antidote to snake bite illustrates different regimes of proof that could be mobilized in favor of a physiological discovery.

A Rare Case of Anal and Perianal Chemical Burn in a Child due to Potassium Permanganate Crystals.

Science.gov (United States)

Dash, Suvashis; Bhojani, Jatin; Sharma, Sharadendu

2018-02-09

Many chemicals used as medical treatments can cause chemical burns as an untoward side effect. One of such chemicals is potassium permanganate. It is a caustic chemical used as a disinfectant. The most common sites of burn by potassium permanganate are exposed sites like the face and hands. Chemical burns in the perianal and anal region are rare in clinical practice and even sparser in the pediatric age group. In this article, we report a case of perianal and anal chemical burn in an 18-month-old, male child, caused by potassium permanganate crystal applied wrongly for the treatment of pinworm infestation. As a chemical burn in this region can have serious complications, it is necessary to be vigilant when using such chemicals in these cases. Early and timely management in such cases leads to good outcomes. This is the first of such cases of chemical burn caused by potassium permanganate in the anal and perianal region.

A Review of Surface Analysis Techniques for the Investigation of the Phenomenon of Electrochemical Promotion of Catalysis with Alkaline Ionic Conductors

Directory of Open Access Journals (Sweden)

Jesús González-Cobos

2016-01-01

Full Text Available Electrochemical Promotion of Catalysis (EPOC with alkali ionic conductors has been widely studied in literature due to its operational advantages vs. alkali classical promotion. This phenomenon allows to electrochemically control the alkali promoter coverage on a catalyst surface in the course of the catalytic reaction. Along the study of this phenomenon, a large variety of in situ and ex situ surface analysis techniques have been used to investigate the origin and mechanism of this kind of promotion. In this review, we analyze the most important contributions made on this field which have clearly evidenced the presence of adsorbed alkali surface species on the catalyst films deposited on alkaline solid electrolyte materials during EPOC experiments. Hence, the use of different surface analysis techniques such as scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDX, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, scanning photoelectron microscopy (SPEM, or scanning tunneling microscopy (STM, led to a better understanding of the alkali promoting effect, and served to confirm the theory of electrochemical promotion on this kind of catalytic systems. Given the functional similarities between alkali electrochemical and chemical promotion, this review aims to bring closer this phenomenon to the catalysis scientific community.

Electrokinetic Enhanced Permanganate Delivery for Low Permeability Soil Remediation

Science.gov (United States)

Chowdhury, A. I.; Gerhard, J.; Reynolds, D. A.; Sleep, B. E.; O'Carroll, D. M.

2016-12-01

Contaminant mass sequestered in low permeability zones (LPZ) in the subsurface has become a significant concern due to back diffusion of contaminants, leading to contaminant rebound following treatment of the high permeability strata. In-situ remediation technologies such as in-situ chemical oxidation (ISCO) are promising, however, successful delivery of oxidants into silts and clays remains a challenge. Electrokinetics (EK) has been proposed as a technique that can overcome this challenge by delivering oxidants into low permeability soils. This study demonstrates the ability of EK to facilitate permanganate delivery into silt for treatment of trichloroethene (TCE). A two-dimensional sandbox was packed with alternate vertical layers of coarse sand and silt contaminated with high concentrations of aqueous phase TCE. Nine experiments were conducted to compare EK-enhanced in-situ chemical oxidation (EK-ISCO) to ISCO alone or EK alone. Frequent groundwater sampling at multiple locations combined with image analysis provided detailed mapping of TCE, permanganate, and manganese dioxide mass distributions. EK-ISCO successfully delivered the permanganate throughout the silt cross-section while ISCO without EK resulted in permanganate delivery only to the edges of the silt layer. EK-ISCO resulted in a 4.4 order-of-magnitude (OoM) reduction in TCE concentrations in the coarse sand compared to a 3.5 OoM reduction for ISCO alone. This study suggests that electrokinetics coupled with ISCO can achieve enhanced remediation of lower permeability strata, where remediation technologies for successful contaminant mass removal would otherwise be limited.

Oxygen isotope effect in 55Mn and 95Mo NMR spectra of the permanganate and molybdate ion

International Nuclear Information System (INIS)

Buckler, K.U.; Haase, A.R.; Lutz, O.; Mueller, M.; Nolle, A.

1977-01-01

By Fourier transform NMR spectroscopy the 55 Mn and 95 Mo resonance lines in the different permanganate and molybdate species Mn 16 Osub(4-n) 18 Osub(n) - and Mo 16 Osub(4-n) 18 Osub(n) 2- (n = 0,1,2,3,4) have been resolved in aqueous solutions of potassium permanganate and sodium molybdate. An isotopic effect on the Larmor frequency for 55 Mn of (0.59+-0.02)ppm and for 95 Mo of (0.25+-0.01)ppm to lower frequency has been found for the substitution of one 16 O atom by one 18 O atom. The relaxation rates 1/T 1 of 55 Mn in the different lines of the permanganate solution are equal within the limits of error. The oxygen exchange rate for the water-permanganate system has been evaluated. (orig.) [de

Kinetics and mechanism for degradation of dichlorvos by permanganate in drinking water treatment.

Science.gov (United States)

Liu, Chao; Qiang, Zhimin; Adams, Craig; Tian, Fang; Zhang, Tao

2009-08-01

The degradation kinetics and mechanism of dichlorvos by permanganate during drinking water treatment were investigated. The reaction of dichlorvos with permanganate was of second-order overall with negligible pH dependence and an activation energy of 29.5 kJ x mol(-1). At pH 7.0 and 25 degrees C, the rate constant was 25.2+/-0.4M(-1)s(-1). Dichlorvos was first degraded to trimethyl phosphate (TMP) and dimethyl phosphate (DMP) simultaneously which approximately accounted for or=95% with respect to phosphorus mass, respectively. Further oxidation of DMP generated a final byproduct, monomethyl phosphate (MMP). MMP was for the first time identified as a major byproduct in chemical oxidation of dichlorvos. The kinetic model based on degradation mechanism and determined reaction rate constants allowed us to predict the evolution of dichlorvos and its byproduct concentrations during permanganate pre-oxidation process at water treatment plants. These results suggest that even though the dichlorvos concentration in surface water complies with the surface water quality standards of China (50 microg L(-1)), its concentration after conventional water treatment will most probably exceed the drinking water quality standards (1 microg L(-1)). Moreover, luminescent bacteria test shows that the acute toxicity of dichlorvos solution evidently increased after permanganate oxidation.

Towards a stable ion-solvating polymer electrolyte for advanced alkaline water electrolysis

DEFF Research Database (Denmark)

Aili, David; Wright, Andrew G.; Kraglund, Mikkel Rykær

2017-01-01

Advanced alkaline water electrolysis using ion-solvating polymer membranes as electrolytes represents a new direction in the field of electrochemical hydrogen production. Polybenzimidazole membranes equilibrated in aqueous KOH combine the mechanical robustness and gas-tightness of a polymer...... stability in alkaline environments. The novel electrolytes are extensively characterized with respect to physicochemical and electrochemical properties and the chemical stability is assessed in 0-50 wt% aqueous KOH for more than 6 months at 88 degrees C. In water electrolysis tests using porous 3...

Oxidation of sulfamethoxazole (SMX) by chlorine, ozone and permanganate--a comparative study.

Science.gov (United States)

Gao, Shanshan; Zhao, Zhiwei; Xu, Yongpeng; Tian, Jiayu; Qi, Hong; Lin, Wei; Cui, Fuyi

2014-06-15

Sulfamethoxazole (SMX), a typical sulfonamide antibiotic, has been widely detected in secondary wastewater effluents and surface waters. In this work we investigated the oxidative degradation of SMX by commonly used oxidants of chlorine, ozone and permanganate. Chlorine and ozone were shown to be more effective for the removal of SMX (0.05-5.0mg/L), as compared with permanganate. Higher pH enhanced the oxidation of SMX by ozone and permanganate, but decreased the removal by chlorine. Moreover, the ozonation of SMX was significantly influenced by the presence of humic acid (HA), which exhibited negligible influence on the oxidation by chlorine and permanganate. Fairly lower mineralization of SMX occurred during the oxidation reactions, with the highest dissolved organic carbon (DOC) removal of 13% (for ozone). By using LC-MS/MS, 7, 5 and 5 oxidation products were identified for chlorine, ozone and permanganate and possible transformation pathways were proposed. It was shown that different oxidants shared some common pathways, such as the cleavage of SN bond, the hydroxylation of the benzene ring, etc. On the other hand, each of the oxidants also exhibited exclusive degradation mechanisms, leading to the formation of different transformation products (TPs). This work may provide useful information for the selection of oxidants in water treatment processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of Smallmouth Buffalo and Potassium Permanganate Treatment on Plankton ans Pond Water Quality

Science.gov (United States)

Removal of intermediate hosts is one option for control of disease in channel catfish production systems. We evaluated use of predaceous fish (smallmouth buffalo) and chemical treatment (potassium permanganate) to remove snails that serve as hosts protecting Dero worms. Both methods of treatment r...

Status of test results of electrochemical organic oxidation of a tank 241-SY-101 simulated waste

International Nuclear Information System (INIS)

Colby, S.A.

1994-06-01

This report presents scoping test results of an electrochemical waste pretreatment process to oxidize organic compounds contained in the Hanford Site's radioactive waste storage tanks. Electrochemical oxidation was tested on laboratory scale to destroy organics that are thought to pose safety concerns, using a nonradioactive, simulated tank waste. Minimal development work has been applied to alkaline electrochemical organic destruction. Most electrochemical work has been directed towards acidic electrolysis, as in the metal purification industry, and silver catalyzed oxidation. Alkaline electrochemistry has traditionally been associated with the following: (1) inefficient power use, (2) electrode fouling, and (3) solids handling problems. Tests using a laboratory scale electrochemical cell oxidized surrogate organics by applying a DC electrical current to the simulated tank waste via anode and cathode electrodes. The analytical data suggest that alkaline electrolysis oxidizes the organics into inorganic carbonate and smaller carbon chain refractory organics. Electrolysis treats the waste without adding chemical reagents and at ambient conditions of temperature and pressure. Cell performance was not affected by varying operating conditions and supplemental electrolyte additions

Oxidation kinetics of polycyclic aromatic hydrocarbons by permanganate

Energy Technology Data Exchange (ETDEWEB)

Forsey, S.P.; Thomson, N.R.; Barker, J.F. [University of Waterloo, Waterloo, ON (Canada). Dept. of Civil & Environmental Engineering

2010-04-15

The reactivity of permanganate towards polycyclic aromatics hydrocarbons (PAHs) is well known but little kinetic information is available. This study investigated the oxidation kinetics of a selected group of coal tar creosote compounds and alkylbenzenes in water using permanganate, and the correlation between compound reactivity and physical/chemical properties. The oxidation of naphthalene, phenanthrene, chrysene, 1-methylnaphthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole isopropylbenzene, ethylbenzene and methylbenzene closely followed pseudo first-order reaction kinetics. The oxidation of pyrene was initially very rapid and did not follow pseudo first-order kinetics at early times. Fluoranthene was only partially oxidized and the oxidation of anthracene was too fast to be captured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene were non-reactive under the study conditions. The oxidation rate was shown to increase with increasing number of polycyclic rings because less energy is required to overcome the aromatic character of a polycyclic ring than is required for benzene. Thus the rate of oxidation increased in the series naphthalene < phenanthrene < pyrene. The rate of side chain reactivity is controlled by the C-H bond strength. For the alkyl substituted benzenes an excellent correlation was observed between the reaction rate coefficients and bond dissociation energies, but for the substituted PAHs the relationship was poor. A trend was found between the reaction rate coefficients and the calculated heats of complexation indicating that significant ring oxidation occurred in addition to side chain oxidation. Clar's aromatic sextet theory was used to predict the relative stability of arenes towards ring oxidation by permanganate.

The impact of pre-oxidation with potassium permanganate on cyanobacterial organic matter removal by coagulation.

Science.gov (United States)

Naceradska, Jana; Pivokonsky, Martin; Pivokonska, Lenka; Baresova, Magdalena; Henderson, Rita K; Zamyadi, Arash; Janda, Vaclav

2017-05-01

The study investigates the effect of permanganate pre-oxidation on the coagulation of peptides/proteins of Microcystis aeruginosa which comprise a major proportion of the organic matter during cyanobacterial bloom decay. Four different permanganate dosages (0.1, 0.2, 0.4 and 0.6 mg KMnO 4 mg -1 DOC) were applied prior to coagulation by ferric sulphate. Moreover, changes in sample characteristics, such as UV 254 , DOC content and molecular weight distribution, after pre-oxidation were monitored. The results showed that permanganate pre-oxidation led to a reduction in coagulant dose, increased organic matter removals by coagulation (by 5-12% depending on permanganate dose), microcystin removal (with reductions of 91-96%) and a shift of the optimum pH range from 4.3 to 6 without to 5.5-7.3 with pre-oxidation. Degradation of organic matter into inorganic carbon and adsorption of organic matter onto hydrous MnO 2 are suggested as the main processes responsible for coagulation improvement. Moreover, permanganate prevented the formation of Fe-peptide/protein complexes that inhibit coagulation at pH about 6.2 without pre-oxidation. The study showed that carefully optimized dosing of permanganate improves cyanobacterial peptide/protein removal, with the benefit of microcystin elimination. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of crystal orientation on the aluminum anodes of the aluminum-air batteries in alkaline electrolytes

Science.gov (United States)

Fan, Liang; Lu, Huimin; Leng, Jing; Sun, Zegao; Chen, Chunbo

2015-12-01

Recently, aluminum-air (Al-air) batteries have received attention from researchers as an exciting option for safe and efficient batteries. The electrochemical performance of Aluminum anode remains an active area of investigation. In this paper, the electrochemical properties of polycrystalline Al, Al (001), (110) and (111) single crystals are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 4 M NaOH and KOH. Hydrogen corrosion rates of the Al anodes are determined by hydrogen collection. Battery performance using the anodes is tested by constant current discharge at 10 mA cm-2. This is the first report showing that the electrochemical properties of Al are closely related to the crystallographic orientation in alkaline electrolytes. The (001) crystallographic plane has good corrosion resistance but (110) is more sensitive. Al (001) single crystals display higher anode efficiency and capacity density. Controlling the crystallographic orientation of the Al anode is another way to improve the performance of Al-air batteries in alkaline electrolytes.

Block Copolymers for Alkaline Fuel Cell Membrane Materials

Science.gov (United States)

2014-07-30

temperature fuel cells including proton exchange membrane fuel cell ( PEMFC ) and alkaline fuel cell (AFC) with operation temperature usually lower than 120...advantages over proton exchange membrane fuel cells ( PEMFCs ) resulting in the popularity of AFCs in the US space program.[8-11] The primary benefit AFC...offered over PEMFC is better electrochemical kinetics on the anode and cathode under the alkaline environment, which results in the ability to use

Oxidation of volatile organic vapours in air by solid potassium permanganate.

Science.gov (United States)

Mahmoodlu, Mojtaba Ghareh; Hartog, Niels; Majid Hassanizadeh, S; Raoof, Amir

2013-06-01

Volatile organic compounds (VOCs) may frequently contaminate groundwater and pose threat to human health when migrating into the unsaturated soil zone and upward to the indoor air. The kinetic of chemical oxidation has been investigated widely for dissolved VOCs in the saturated zone. But, so far there have been few studies on the use of in situ chemical oxidation (ISCO) of vapour phase contaminants. In this study, batch experiments were carried out to evaluate the oxidation of trichloroethylene (TCE), ethanol, and toluene vapours by solid potassium permanganate. Results revealed that solid potassium permanganate is able to transform the vapour of these compounds into harmless oxidation products. The degradation rates for TCE and ethanol were higher than for toluene. The degradation process was modelled using a kinetic model, linear in the gas concentration of VOC [ML(-3)] and relative surface area of potassium permanganate grains (surface area of potassium permanganate divided by gas volume) [L(-1)]. The second-order reaction rate constants for TCE, ethanol, and toluene were found to be equal to 2.0×10(-6) cm s(-1), 1.7×10(-7) cm s(-1), and 7.0×10(-8) cm s(-1), respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimization of permanganic etching of polyethylenes for scanning electron microscopy

International Nuclear Information System (INIS)

Naylor, K.L.; Phillips, P.J.

1983-01-01

The permanganic etching technique has been studied as a function of time, temperature, and concentration for a series of polyethylenes. Kinetic studies show that a film of reaction products builds up on the surface, impeding further etching, an effect which is greatest for the lowest-crystallinity polymers. SEM studies combined with EDS show that the film contains sulfur, potassium and some manganese. An artifact is produced by the etching process which is impossible to remove by washing procedures if certain limits of time, temperature, and concentration are exceeded. For lower-crystallinity polyethylenes multiple etching and washing steps were required for optimal resolution. Plastic deformation during specimen preparation, whether from scratches or freeze fracturing, enhances artifact formation. When appropriate procedures are used, virtually artifact-free surfaces can be produced allowing a combination of permanganic etching and scanning electron microscopy to give a rapid method for detailed morphological characterization of bulk specimens

Thermal annealing of recoil 56Mn in strontium permanganate under (n,γ) process

International Nuclear Information System (INIS)

Mishra, Shuddhodan P.; Vijaya

2002-01-01

Chemical stabilization of recoil 56 Mn in strontium permanganate (hydrous and anhydrous) has been investigated with a special reference to pre-and post-activation thermal annealing treatments. The retention of 56 Mn in neutron irradiated strontium permanganate showed significant variation on thermal annealing in both pre-and post-activation heated target. The recoil re-entry process obeys simple first order kinetics and the activation energy deduced for thermal annealing process is very low as computed by classical Arrhenius plots. The results observed are discussed in the light of existing ideas for understanding the recoil stabilization mechanism of parent reformation and the nature of precursors in permanganates. (author)

Permanganate oxidation of sulfur compounds to prevent poisoning of Pd catalysts in water treatment processes.

Science.gov (United States)

Angeles-Wedler, Dalia; Mackenzie, Katrin; Kopinke, Frank-Dieter

2008-08-01

The practical application of Pd-catalyzed water treatment processes is impeded by catalyst poisoning by reduced sulfur compounds (RSCs). In this study, the potential of permanganate as a selective oxidant for the removal of microbially generated RSCs in water and as a regeneration agent for S-poisoned catalysts was evaluated. Hydrodechlorination using Pd/Al2O3 was carried out as a probe reaction in permanganate-pretreated water. The activity of the Pd catalysts in the successfully pretreated reaction medium was similar to that in deionized water. The catalyst showed no deactivation behavior in the presence of permanganate at a concentration level or = 0.08 mM, a significant but temporary inhibition of the catalytic dechlorination was observed. Unprotected Pd/Al2O3, which had been completely poisoned by sulfide, was reactivated by a combined treatment with permanganate and hydrazine. However, the anthropogenic water pollutants thiophene and carbon disulfide were resistant against permanganate. Together with the preoxidation of catalyst poisons, hydrophobic protection of the catalysts was studied. Pd/zeolite and various hydrophobically coated catalysts showed a higher stability against ionic poisons and permanganate than the uncoated catalyst. By means of a combination of oxidative water pretreatment and hydrophobic catalyst protection, we provide a new tool to harness the potential of Pd-catalyzed hydrodehalogenation for the treatment of real waters.

Passivation behavior of a ferritic stainless steel in concentrated alkaline solutions

Directory of Open Access Journals (Sweden)

Arash Fattah-alhosseini

2015-10-01

Full Text Available The passivation behavior of AISI 430 ferritic stainless steel was investigated in concentrated alkaline solutions in relation to several test parameters, using electrochemical techniques. Increasing solution pH (varying from 11.5 to 14.0 leads to an increase in the corrosion rate of the alloy. Mott–Schottky analysis revealed that passive films formed on AISI 430 ferritic stainless steel behave as n-type semiconductor and the donor densities increased with pH. Electrochemical impedance spectroscopy (EIS results showed that the reciprocal capacitance of the passive film is directly proportional to its thickness, which decreases with pH increase. The results revealed that for this ferritic stainless steel in concentrated alkaline solutions, decreasing the solution pH offers better conditions for forming passive films with higher protection behavior, due to the growth of a much thicker and less defective film.

Electrochemical behavior of NixW1−x materials as catalyst for hydrogen evolution reaction in alkaline media

International Nuclear Information System (INIS)

Oliver-Tolentino, Miguel A.; Arce-Estrada, Elsa M.; Cortés-Escobedo, Claudia A.; Bolarín-Miro, Ana M.; Sánchez-De Jesús, Félix; González-Huerta, Rosa de G.; Manzo-Robledo, Arturo

2012-01-01

Highlights: ► The electrochemical techniques used in this study elucidated the Ni–W surface state. ► The Ni–W materials were effective for the hydrogen evolution reaction. ► The prepared alloys exhibited higher catalytic activity than their precursors. ► The preparation method is relatively simple and effective procedure. - Abstract: In the present work, results of electrochemical evaluation, as well as morphological and structural characterization of Ni x W 1−x materials with x = 0.77, 0.64, 0.4, 0.19 and 0.07 processed by means of high energy ball milling from high purity powders are presented. Also, the electrocatalytic performance on the hydrogen evolution reaction (HER) of the Ni x W 1−x materials evaluated by linear polarization and cyclic voltammetry techniques in alkaline media at room temperature is discussed. The structural and morphological characterization of the as-prepared materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated a small-particle clusters and solid solution formation. According to the kinetics parameters the best electrocatalytic activity was observed at Ni 64 W 36 .

The use of permanganate as a sequencing reagent for identification of 5-methylcytosine residues in DNA.

OpenAIRE

Fritzsche, E; Hayatsu, H; Igloi, G L; Iida, S; Kössel, H

1987-01-01

The use of permanganate as a reagent for DNA sequencing by chemical degradation has been studied with respect to its specificity for 5-methylcytosine residues. At weakly acidic pH and room temperature, 0.2 mM potassium permanganate reacts preferentially with thymine, 5-methylcytosine, and to a lesser extent with purine residues, while cytosine remains essentially intact. Permanganate oxidation is, therefore, a suitable DNA sequencing reaction for positive discrimination between 5-methylcytosi...

Electrochemical oxidation of ethanol using PtRh/C electrocatalysts in alkaline medium and synthesized by sodium borohydride and alcohol reduction

International Nuclear Information System (INIS)

Fontes, Eric Hossein

2017-01-01

PtRh/C were prepared by the following atomic proportions: (100,0), (0,100), (90,10), (70,30) and (50,50). The methods employed in the synthesis of these materials were reduction by sodium borohydride and reduction by alcohol. The metal salts used were H 2 PtCl 6 3•6H 2 0 and (RhNO 3 ) 3 , the support used was Carbon black XC72 and the bulk metal composition was 20% and 80% of support. The electrocatalysts were characterized by Energy Dispersive X-ray spectroscopy, X-ray diffraction and Transmission electron microscopy. The ethanol electrochemical oxidation mechanism was investigated by in situ Fourier Transform Infrared Spectroscopy couple to an Attenuated Total Reflection technique. The electrocatalytic activity were evaluated by Cyclic Voltammetry, Linear Sweep Voltammetry and Chronoamperometry techniques. The Fuel Cells tests were made in a single direct alcohol fuel cell with alkaline membrane. The working electrodes were prepared by a thin porous coating technique. X-ray diffraction allowed to verify metallic alloys, segregate phases and to calculate the percentage of metallic alloys. It was else possible to identify crystallographic phases. Infrared Spectroscopy allowed to verify that the electrochemical oxidation of ethanol was carried out by an incomplete mechanism. PtRh(70:30)/C prepared by sodium borohydride produced large amounts of carbon dioxide and acetaldehyde. Rh/C showed electrocatalytic activity when compared with other materials studied.

Reactions of hypoiodous acid with model compounds and the formation of iodoform in absence/presence of permanganate.

Science.gov (United States)

Zhao, Xiaodan; Ma, Jun; von Gunten, Urs

2017-08-01

The kinetics for the reactions of hypoiodous acid (HOI) with various phenols (phenol, 4-nitrophenol, 4-hydroxybenzoic acid), 3-oxopentanedioic acid (3-OPA) and flavone were investigated in the pH range of 6.0-11.0. The apparent second order rate constants for the reactions of HOI with phenolic compounds, 3-OPA, flavone and citric acid at pH 8.0 are 10-10 7  M -1 s -1 , (4.0 ± 0.3) × 10 3  M -1 s -1 , (2.5 ± 0.2) × 10 3  M -1 s -1 and permanganate/HOI/3-OPA and permanganate/iodide/3-OPA system at pH permanganate. For pH > 8.0, in presence of permanganate, iodoform formation is significantly inhibited and iodate formation enhanced, which is due to a faster permanganate-mediated HOI disproportionation to iodate compared to the iodination process. The production of reactive iodine in real waters containing iodide in contact with permanganate may lead to the formation of iodinated organic compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of Anabaena spiroides by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution.

Science.gov (United States)

Qiao, Junlian; Zhang, Xiaodong; Lv, Liping

2017-11-01

Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate

International Nuclear Information System (INIS)

He Di; Guan Xiaohong; Ma Jun; Yang Xue; Cui Chongwei

2010-01-01

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai) > soil HAs > commercial HA (Fluka) > aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of C=C moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R 2 > 0.75) implied that π-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The π-π interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH = 7.0.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate.

Science.gov (United States)

He, Di; Guan, Xiaohong; Ma, Jun; Yang, Xue; Cui, Chongwei

2010-10-15

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai)>soil HAs>commercial HA (Fluka)>aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of CC moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R(2)>0.75) implied that pi-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The pi-pi interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH=7.0. 2010 Elsevier B.V. All rights reserved.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate

Energy Technology Data Exchange (ETDEWEB)

He Di, E-mail: hedy1997@hotmail.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Guan Xiaohong, E-mail: hitgxh@126.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Ma Jun, E-mail: majun@hit.edu.cn [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Yang Xue, E-mail: yangxue1_ok@163.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Cui Chongwei, E-mail: cuichongwei1991@126.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China)

2010-10-15

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai) > soil HAs > commercial HA (Fluka) > aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of C=C moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R{sup 2} > 0.75) implied that {pi}-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The {pi}-{pi} interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH = 7.0.

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

International Nuclear Information System (INIS)

Liu Ling; Zhao Yaomin; Jia Nengqin; Zhou Qin; Zhao Chongjun; Yan Manming; Jiang Zhiyu

2006-01-01

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium-tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

Energy Technology Data Exchange (ETDEWEB)

Ling, Liu [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Yaomin, Zhao [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Nengqin, Jia [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Qin, Zhou [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Chongjun, Zhao [Photon Craft Project, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences and Japan Science and Technology Agency, Shanghai 201800 (China); Manming, Yan [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Zhiyu, Jiang [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China)

2006-05-01

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium-tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers.

Kinetic and Mechanistic Aspects of the Reactions of Iodide and Hypoiodous Acid with Permanganate: Oxidation and Disproportionation.

Science.gov (United States)

Zhao, Xiaodan; Salhi, Elisabeth; Liu, Huiling; Ma, Jun; von Gunten, Urs

2016-04-19

Oxidation kinetics of iodide and HOI/OI(-) by permanganate were studied in the pH range of 5.0-10.0. Iodide oxidation and iodate formation were faster at lower pH. The apparent second-order rate constants (k(obs)) for iodide oxidation by permanganate decrease with increasing pH from 29 M(-1) s(-1) at pH 5.0 and 6.9 M(-1) s(-1) at pH 7.0 to 2.7 M(-1) s(-1) at pH 10.0. k(obs) for HOI abatement are 56 M(-1) s(-1) at pH 5.0, 2.5 M(-1) s(-1) at pH 7.0, and 173 M(-1) s(-1) at pH 10.0. Iodate yields over HOI abatement decrease from 98% at pH 6.0 to 33% for pH ≥ 9.5, demonstrating that HOI disproportionation dominates HOI transformation by permanganate at pH ≥ 8.0. MnO2 formed as a product from permanganate reduction, oxidizes HOI to iodate for pH oxidation or disproportionation induced by MnO2 is much lower than for permanganate. During treatment of iodide-containing waters, the potential for iodinated disinfection byproducts (I-DBPs) formation is highest at pH 7.0-8.0 due to the long lifetime of HOI. For pH oxidized by permanganate to iodate, whereas for pH ≥ 8.0, HOI/OI(-) undergoes a fast permanganate-mediated disproportionation.

Manganese Dioxide Coated Graphene Nanoribbons Supported Palladium Nanoparticles as an Efficient Catalyst for Ethanol Electrooxidation in Alkaline Media

International Nuclear Information System (INIS)

Liu, Qi; Jiang, Kun; Fan, Jinchen; Lin, Yan; Min, Yulin; Xu, Qunjie; Cai, Wen-Bin

2016-01-01

Design of appropriate supporting materials is an alternative route to yield efficient Pt-free catalysts for ethanol oxidation reaction, which in practice may determine the conversion efficiency of direct alkaline ethanol fuel cells. In this work, graphene nanoribbons (GNRs) coated with MnO_2 are used as a unique supporting material for loading and dispersing Pd nanoparticles. XRD, TEM and XPS are applied to characterize the structure of as-synthesized Pd/MnO_2/GNRs nanocomposite catalyst, revealing a good dispersion as well as a modification of electronic property of Pd nanoparticles. Electrochemical measurements demonstrate that the as-synthesized nanocomposite displays largely enhanced electrocatalytic activity and durability toward ethanol oxidation in alkaline media as compared to the other tested Pd-based catalysts with various supports.

The Alkaline Diet: Is There Evidence That an Alkaline ph Diet Benefits Health?

International Nuclear Information System (INIS)

Schwalfenberg, G.K.

2012-01-01

This review looks at the role of an alkaline diet in health. Pub med was searched looking for articles on ph, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine

[Reactivity of several classes of pesticides with UV, ozone and permanganate].

Science.gov (United States)

Liu, Chao; Qiang, Zhi-min; Tian, Fang; Zhang, Tao

2009-01-01

The reactivity of eight classes of 26 extensively used pesticides, namely, organochlorines, thiadiazole, dinitroanaline, acetamides, triazines, uracil and carbamates, with three common disinfectants or oxidants including UV254 (average intensity of 10.8 mW x cm(-2)), ozone (dosage of 4.1 - 6.2 mg x L(-1)) and permanganate (dosage of 15.8 mg x L(-1)) was investigated. The reactions were allowed to proceed for 30 min at pH 7.0 and ambient temperature (25 degrees C +/- 3 degrees C). Results indicate that under the applied experimental conditions, more than 95% of chlorobenzilate, etridiazole, alachlor, butachlor, metolachlor, propachlor, atrazine, simazine, aldicarb, oxamyl and methiocarb could be effectively removed by UV254; and the removal efficiencies of other pesticides were in a range of 12.9%-77.7%. Ozone could completely degrade chloroneb, dichlorvos, bromacil, aldicarb, carbaryl, carbofuran, oxamyl and methiocarb; prometon and aldicarb sulfone were resistant to ozonation; and the removal efficiencies of other pesticides varied from 19.0% to 93.1%. Permanganate could fully degrade dichlorvos, aldicarb and methiocarb; organochlorines, dinitroanaline, thiadiazole, acetamides and other carbamates were resistant to permanganate oxidation; and the removal efficiencies of other pesticides ranged from 16.0% to 88.2%. If the practical dosage applied in drinking water treatment is considered, it is expected that most of the pesticides will be completely degraded by ozone, a few by permanganate, but probably none by UV254 .

Study and optimisation of manganese oxide-based electrodes for electrochemical supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Staiti, P.; Lufrano, F. [CNR-ITAE, Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' , Via Salita S. Lucia n. 5, 98126 S. Lucia, Messina (Italy)

2009-02-01

A manganese oxide material was synthesised by an easy precipitation method based on reduction of potassium permanganate(VII) with a manganese(II) salt. The material was treated at different temperatures to study the effect of thermal treatment on capacitive property. The best capacitive performance was obtained with the material treated at 200 C. This material was used to prepare electrodes with different amounts of polymer binder, carbon black and graphite fibres to individuate the optimal composition that gave the best electrochemical performances. It was found that graphite fibres improve the electrochemical performance of electrodes. The highest specific capacitance (267 F g{sup -1} MnO{sub x}) was obtained with an electrode containing 70% of MnO{sub x}, 15% of carbon black, 10% of graphite fibres and 5% of PVDF. This electrode, with CB/GF ratio of 1.5, showed a higher utilization of manganese oxide. The results reported in the present paper further confirmed that manganese oxide is a very interesting material for supercapacitor application. (author)

Evaluation of electrochemical ion exchange for cesium elution

International Nuclear Information System (INIS)

Bontha, J.D.; Kurath, D.E.; Surma, J.E.; Buehler, M.F.

1996-04-01

Electrochemical elution was investigated as an alternative method to acid elution for the desorption of cesium from loaded ion exchange resins. The approach was found to have several potential advantages over existing technologies, in particular, electrochemical elution eliminates the need for addition of chemicals to elute cesium from the ion exchange resin. Also, since, in the electrochemical elution process the eluting solution is not in direct contact with the ion exchange material, very small volumes of the eluting solution can be used in a complete recycle mode in order to minimize the total volume of the cesium elute. In addition, the cesium is eluted as an alkaline solution that does not require neutralization with caustic to meet the tank farm specifications. Other advantages include easy incorporation of the electrochemical elution process into the present cesium recovery schemes

Mode of corrosion monitoring by electrochemical measurements in alkaline water solutions at 310 degC using a new type of industrial probes with high radiation stability

International Nuclear Information System (INIS)

Beran, J.

1977-01-01

Application of the linear polarization method to Zr-alloys and low-alloy steel was successfully verified by autoclave tests in alkaline water solutions, pH=10.3 max. The new type of industrial probes for electrochemical measurements worked 5500 hours at temperatures within 250 and 310 degC. Contrary to usual practice, the corrosion rate was evaluated applying the criterion T/Rsub(p) instead of criterion 1/Rsub(p). A single calibration curve T/Rsub(p) versus corrosion rate, which is independent of test temperature, was introduced in this way. The probes, developed by SKODA-Works, Nuclear Power Construction Division for electrochemical measurements in nuclear reactor environment, do not contain organic compounds (for sealing, insulation etc.) in order to prevent radiation damage. (author)

Cyanobacterial Treatment Options: Permanganate and Powdered Activated Carbon

Science.gov (United States)

This presentation will begin with a brief overview of drinking water treatment options for cyanobacteria and their toxins. The treatment discussion will focus on the impacts of permanganate addition to suspensions of toxin-producing Microcystis aeruginosa, followed by powdered ac...

Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate.

Science.gov (United States)

Hort, Ryan D; Revil, André; Munakata-Marr, Junko

2014-09-01

Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA

Science.gov (United States)

Harte, Philip T.; Smith, Thor E.; Williams, John H.; Degnan, James R.

2012-01-01

In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment.

Design Tool for Planning Permanganate Injection Systems

Science.gov (United States)

2010-08-01

Chemical Spill 10 CSTR continuously stirred tank reactors CT contact time EDB ethylene dibromide ESTCP Environmental Security Technology...63 6.2 Simulating Oxidant Distribution Using a Series of CSTRs ...ER- 0625. 6.2 SIMULATING OXIDANT DISTRIBUTION USING A SERIES OF CSTRS 6.2.1 MODEL DEVELOPMENT The transport and consumption of permanganate

Evaluation of the kinetic oxidation of aqueous volatile organic compounds by permanganate

NARCIS (Netherlands)

Mahmoodlu, M.G.; Hassanizadeh, S.M.; Hartog, Niels

2014-01-01

The use of permanganate solutions for in-situ chemical oxidation (ISCO) is a well-established groundwater remediation technology, particularly for targeting chlorinated ethenes. The kinetics of oxidation reactions is an important ISCO remediation design aspect that affects the efficiency and oxidant

Evaluation of potassium permanganate against an experimental subacute infection of Flavobacterium columnare in channel catfish, Icatlurus punctatus

Science.gov (United States)

The efficacy of potassium permanganate (KMnO4) as a prophylactic and therapeutic treatment for subacute infection of Flavobacterium columnare was demonstrated in experimentally infected channel catfish, Ictalurus punctatus. Catfish experimentally infected with F. columnare to mimic a subacute infec...

Chemically durable polymer electrolytes for solid-state alkaline water electrolysis

Science.gov (United States)

Park, Eun Joo; Capuano, Christopher B.; Ayers, Katherine E.; Bae, Chulsung

2018-01-01

Generation of high purity hydrogen using electrochemical splitting of water is one of the most promising methods for sustainable fuel production. The materials to be used as solid-state electrolytes for alkaline water electrolyzer require high thermochemical stability against hydroxide ion attack in alkaline environment during the operation of electrolysis. In this study, two quaternary ammonium-tethered aromatic polymers were synthesized and investigated for anion exchange membrane (AEM)-based alkaline water electrolyzer. The membranes properties including ion exchange capacity (IEC), water uptake, swelling degree, and anion conductivity were studied. The membranes composed of all C-C bond polymer backbones and flexible side chain terminated by cation head groups exhibited remarkably good chemical stability by maintaining structural integrity in 1 M NaOH solution at 95 °C for 60 days. Initial electrochemical performance and steady-state operation performance were evaluated, and both membranes showed a good stabilization of the cell voltage during the steady-state operation at the constant current density at 200 mA/cm2. Although both membranes in current form require improvement in mechanical stability to afford better durability in electrolysis operation, the next generation AEMs based on this report could lead to potentially viable AEM candidates which can provide high electrolysis performance under alkaline operating condition.

A Comparative Electrochemical-Ozone Treatment for Removal of Phenolphthalein

Directory of Open Access Journals (Sweden)

V. M. García-Orozco

2016-01-01

Full Text Available The degradation of aqueous solutions containing phenolphthalein was carried out using ozone and electrochemical processes; the two different treatments were performed for 60 min at pH 3, pH 7, and pH 9. The electrochemical oxidation using boron-doped diamond electrodes processes was carried out using three current density values: 3.11 mA·cm−2, 6.22 mA·cm−2, and 9.33 mA·cm−2, whereas the ozone dose was constantly supplied at 5±0.5 mgL−1. An optimal degradation condition for the ozonation treatment is at alkaline pH, while the electrochemical treatment works better at acidic pH. The electrochemical process is twice better compared with ozonation.

Electrochemical reduction of oxygen on lead-silver alloys in an alkaline medium

International Nuclear Information System (INIS)

Seliverstov, S.D.; Arkhangel'skaya, Z.P.; Lyzlov, N.Y.

1986-01-01

The use of lead-silver alloys as materials for the gas-absorbing electrode in sealed silver-cadmium alkaline storage batteries is desirable primarily from the stanpoint of saving the costly silver. The authors studied reduction of oxygen with the aim of optimizing the composition of the Pb-Ag alloy and of the porous structure of the electrodes. The alloys were made in a muffle furnace in corundum crucibles under a layer of VI-2 flux. Curves are shown which represent the dependence of the ionization current of molecular oxygen on smooth partially immersed electrodes made from alloys differing in composition on the length of the part of the electrode withdrawn from the solution. It is shown that decrease of the corrosion resistance of the alloy in the porous electrode causes partial loss of its mechanical strength. Worsening of the electric contact between the particles of active material is also possible. An alloy of the composition (mass %) 60 Pb-40 Ag is the most suitable from the practical standpoint

Electrochemical Oxidation of Glycerol Using Gold Electrode

International Nuclear Information System (INIS)

Mohamed Rozali Othman; Amirah Ahmad

2015-01-01

Cyclic voltammetry, potential linear V and chronocuolometry methods were carried out to gain electrochemical behavior of glycerol at a gold electrode. Potassium hydroxide and sulfuric acid were chosen to be the electrolyte for the electro-oxidation of this organic compound. Besides gold plate electrode, gold composite electrode (Au-PVC) was also used as the working electrode. The Au-PVC composite electrode was characterized by Scanning Electron Microscopy (SEM) to determine its morphological aspects before and after used in electrochemical oxidation of glycerol. In alkaline solution, the adsorption of hydroxide species onto the surface of both gold plate and composite Au-PVC electrodes occurs at potential around 500 mV vs SCE. However, at gold plate electrode, there was a small, broad peak before the drastic escalation of current densities which indicates the charge transfer of the chemisorbed OH - anion. In acidic media, the gold oxide was formed after potential 1.0 V. From the cyclic voltammogram glycerol undergo oxidation twice in potassium hydroxide at gold plate and Au-PVC composite electrodes, while in sulfuric acid, oxidation reaction happened once for glycerol on the gold plate electrode. Overall, electrochemical oxidation of glycerol was more effective in alkaline media. Tafel graph which plotted from potential linear V method shows that Au-PVC composite electrode is better than gold plate electrode for the electro-oxidation of glycerol in alkaline solution. Electrochemical oxidation of glycerol products as analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) produced several carboxylic acids and phenolic compounds. (author)

Chemiluminescence evidence supporting the selective role of ligands in the permanganate oxidation of micropollutants.

Science.gov (United States)

Roderick, Mark S; Adcock, Jacqui L; Terry, Jessica M; Smith, Zoe M; Parry, Samuel; Linton, Stuart M; Thornton, Megan T; Barrow, Colin J; Francis, Paul S

2013-10-10

The selective increase in the oxidation rate of certain organic compounds with permanganate in the presence of environmental "ligands" and reduced species has been ascribed to the different reactivity of the target compounds toward Mn(III), which bears striking similarities to recent independent investigations into the use of permanganate as a chemiluminescence reagent. In spite of the importance of Mn(III) in the light-producing pathway, the dependence of the oxidation mechanism for any given compound on this intermediate could not be determined solely through the emission intensity. However, target compounds susceptible to single-electron oxidation by Mn(III) (such as bisphenol A and triclosan) can be easily distinguished by the dramatic increase in chemiluminescence intensity when a permanganate reagent containing high, stable concentrations of Mn(III) is used. The differences are accentuated under the low pH conditions that favor the chemiluminescence emission due to the greater reactivity of Mn(III) and the greater influence of complexing agents. This study supports the previously postulated selective role of ligands and reducing agents in permanganate oxidations and demonstrates a new approach to explore the chemistry of environmental manganese redox processes.

Radioactive Demonstration of Caustic Recovery from Low-Level Alkaline Nuclear Waste by an Electrochemical Separation Process

International Nuclear Information System (INIS)

Hobbs, D.T.

1998-04-01

Bench-scale radioactive tests successfully demonstrated an electrochemical process for the recovery of sodium hydroxide (caustic) from Decontaminated Salt Solution produced from the In-Tank Precipitation and Effluent Treatment Processes at the Savannah River Site (SRS). This testing evaluated two membranes: an organic-based membrane, Nafion Type 350, manufactured by E. I. duPont de Nemours ampersand Company, Inc. (DuPont) and an inorganic-based membrane, NAS D, being developed by Ceramatec. Both membranes successfully separated caustic from radioactive SRS waste.Key findings of the testing indicate the following attributes and disadvantages of each membrane. The commercially-available Nafion membrane proved highly conductive. Thus, the electrochemical cell can operate at high current density minimizing the number of cells at the desired volumetric processing rate. Testing indicated cesium transported across the Nafion membrane into the caustic product. Therefore, the caustic product will contain low-levels of radioactive cesium due to the presence of 134,137 Cs in the waste feed. To meet customer requirements, a post treatment stage may prove necessary to remove radioactive cesium resulting in increased overall process costs and decreased cost savings. In contrast to the Nafion membrane, the NAS D membrane demonstrated the production of caustic with much lower levels of gamma radioactivity ( 137 Cs activity was < 51 dpm/g). Therefore, the caustic product could possibly release for onsite/offsite use without further treatment. The NAS D membrane remains in the development stage and does not exist as a commercial product. Operating costs and long-term membrane durability remain unknown.Caustic recovery has been successfully demonstrated in a bench-scale, 2-compartment electrochemical reactor operated for brief periods of time with simulated and radioactive waste solutions and two different types of membranes. The next phase of testing should be directed at (1

[An application of electrochemical detector to dental pharmacology].

Science.gov (United States)

Sakai, J

1990-03-01

The electrochemical detection (ECD) is highly sensitive and can distinguish selectively electrochemically active materials. A sensitive and selective ECD is widely used for high-performance liquid chromatography (HPLC) of phenolic compounds, such as catecholamines, indoleamines and phenolic steroids in biological materials. In the present study, the HPLC/ECD system was applied for the simultaneous determination of various dental drugs, such as phenol, guaiacol, m-cresol, o-chlorophenol, p-chlorophenol, m-chlorophenol, eugenol, pyrogallol and resorcin. As a compromise between sensitivity and stability, the applied voltage was set at 1.2 V vs the reference electrode. These drugs were rapidly and selectively separated on a reversed-phase column using 10 mM acetate buffer (pH 4.0)-methanol (7:3, v/v) as a mobile phase. The detection limits of these drugs were determined to be 0.25 pmol per injection. These results imply that the HPLC/ECD method should be capable of determining these dental drugs with high sensitivity. The ECD was also applied to determine the enzyme activity. A highly sensitive and specific assay for alkaline and acid phosphatases and N-acetyl-beta-glucosaminidase in biological materials, such as plasma, saliva and bone, has been established. Phenol, formed enzymatically from the substrate, was determined by HPLC/ECD. The retention time of phenol was 7 min and no other peaks were observed. The method is rapid and sensitive with a detection limit for phenol of as little as 0.5 pmol. Thus, as little as 0.5 microliters of rat plasma or 10 microliters of human saliva is all that is required for both alkaline and acid phosphatase assays. The assay is accurate and reproducible. Using this assay, alkaline and acid phosphatase activities in human saliva and in rat saliva elicited by pilocarpine and isoproterenol were determined. It will be possible to apply this new assay method to extremely small biological samples. Thus, the application of the HPLC

Electrochemical behavior of Ni{sub x}W{sub 1-x} materials as catalyst for hydrogen evolution reaction in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Oliver-Tolentino, Miguel A. [UPIBI-IPN, Departamento de Ciencias Basicas, Av. Acueducto s/n, Barrio La Laguna, Col. Ticoman, Mexico D.F. 07340 (Mexico); Arce-Estrada, Elsa M. [ESIQIE-IPN Departamento de Ingenieria en Metalurgia y Materiales, UPALM, UPALM, Mexico D.F. 07738 (Mexico); Cortes-Escobedo, Claudia A. [Centro de Investigacion e Innovacion Tecnologica del IPN, Cda. Cecati s/n, Col. Sta. Catarina, CP 02250 Azcapotzalco D.F. (Mexico); Bolarin-Miro, Ana M.; Sanchez-De Jesus, Felix [Area Academica de Ciencias de la Tierra y Materiales, Universidad Autonoma del Estado de Hidalgo, CU, Carr. Pachuca-Tulancingo Km. 4.5, Mineral de la Reforma, CP 42184 Hidalgo (Mexico); Gonzalez-Huerta, Rosa de G. [ESIQIE-IPN, Departamento de Ingenieria Quimica - Laboratorio de Electroquimica y Corrosion, Edif. Z-5 3er piso, UPALM, Mexico D.F. 07738 (Mexico); Manzo-Robledo, Arturo, E-mail: amanzor@ipn.mx [ESIQIE-IPN, Departamento de Ingenieria Quimica - Laboratorio de Electroquimica y Corrosion, Edif. Z-5 3er piso, UPALM, Mexico D.F. 07738 (Mexico)

2012-09-25

Highlights: Black-Right-Pointing-Pointer The electrochemical techniques used in this study elucidated the Ni-W surface state. Black-Right-Pointing-Pointer The Ni-W materials were effective for the hydrogen evolution reaction. Black-Right-Pointing-Pointer The prepared alloys exhibited higher catalytic activity than their precursors. Black-Right-Pointing-Pointer The preparation method is relatively simple and effective procedure. - Abstract: In the present work, results of electrochemical evaluation, as well as morphological and structural characterization of Ni{sub x}W{sub 1-x} materials with x = 0.77, 0.64, 0.4, 0.19 and 0.07 processed by means of high energy ball milling from high purity powders are presented. Also, the electrocatalytic performance on the hydrogen evolution reaction (HER) of the Ni{sub x}W{sub 1-x} materials evaluated by linear polarization and cyclic voltammetry techniques in alkaline media at room temperature is discussed. The structural and morphological characterization of the as-prepared materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated a small-particle clusters and solid solution formation. According to the kinetics parameters the best electrocatalytic activity was observed at Ni{sub 64}W{sub 36}.

Oxidative elimination of cyanotoxins: comparison of ozone, chlorine, chlorine dioxide and permanganate.

Science.gov (United States)

Rodríguez, Eva; Onstad, Gretchen D; Kull, Tomas P J; Metcalf, James S; Acero, Juan L; von Gunten, Urs

2007-08-01

As the World Health Organization (WHO) progresses with provisional Drinking Water Guidelines of 1 microg/L for microcystin-LR and a proposed Guideline of 1 microg/L for cylindrospermopsin, efficient treatment strategies are needed to prevent cyanotoxins such as these from reaching consumers. A kinetic database has been compiled for the oxidative treatment of three cyanotoxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-a (ANTX) with ozone, chlorine, chlorine dioxide and permanganate. This kinetic database contains rate constants not previously reported and determined in the present work (e.g. for permanganate oxidation of ANTX and chlorine dioxide oxidation of CYN and ANTX), together with previously published rate constants for the remaining oxidation processes. Second-order rate constants measured in pure aqueous solutions of these toxins could be used in a kinetic model to predict the toxin oxidation efficiency of ozone, chlorine, chlorine dioxide and permanganate when applied to natural waters. Oxidants were applied to water from a eutrophic Swiss lake (Lake Greifensee) in static-dose testing and dynamic time-resolved experiments to confirm predictions from the kinetic database, and to investigate the effects of a natural matrix on toxin oxidation and by-product formation. Overall, permanganate can effectively oxidize ANTX and MC-LR, while chlorine will oxidize CYN and MC-LR and ozone is capable of oxidizing all three toxins with the highest rate. The formation of trihalomethanes (THMs) in the treated water may be a restriction to the application of sufficiently high-chlorine doses.

Degradation of amaranth dye in alkaline medium by ultrasonic cavitation coupled with electrochemical oxidation using a boron-doped diamond anode

International Nuclear Information System (INIS)

Barros, Willyam R.P.; Steter, Juliana R.; Lanza, Marcos R.V.; Motheo, Artur J.

2014-01-01

Amaranth dye is used widely in the processing of paper, textiles, foods, cosmetics, beverages and medicines, and effluents contaminated with this compound are discharged daily into the environment. Recent studies have shown that azo dyes, especially those such as amaranth dye that have been classified as endocrine disruptors, may cause adverse effects to animal and human health. This paper describes the application of electrochemical oxidation (with a boron-doped diamond BDD thin-film anode) coupled with ultrasound sonolysis (20 kHz and 523 W cm −2 ) to the removal of amaranth dye from dilute alkaline solution. The electrochemical and sonoelectrochemical processes (ECh and SECh, respectively) were carried out at constant current density (10 to 50 mA cm −2 ) in a single compartment cylindrical cell. Sonolysis was virtually less useful for the decolorization and degradation of amaranth dye, whilst ECh and SECh were more effective in degrading the dye with almost complete removal (90 - 95%) attained after 90 min of experiment at an applied current density of 50 mA cm −2 . Degradation of the dye followed pseudo first-order kinetics in both processes, but the rate of reaction was faster with the SECh treatment confirming a synergistic effect between the cavitation process and the electrochemical system. Additionally, at low applied current densities (10 and 25 mA cm −2 ), SECh was considerably more effective than ECh for the amaranth dye mineralization. Although at 35 and 50 mA cm −2 , the two processes showed the respective removal of total organic carbon values: (i) 85% for the ECh and 90% for the SECh at 35 mA cm −2 ; (ii) 96% for the ECh and 98% for the SECh at 50 mA cm −2 . It is concluded that SECh presented the most favorable results for the decontamination of wastewaters containing azo dye compounds

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate

International Nuclear Information System (INIS)

Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

2014-01-01

Graphical abstract: - Highlights: • Transport experiments used transmissive and low permeability zones (LPZs). • 14 C-labeled TCE was used to quantify oxidation of DNAPL in LPZs by permanganate. • Stabilization aids prevented MnO 2 rind formation. • DNAPL oxidation improved when xanthan and stabilization aids were used. - Abstract: Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO 4 − ) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase 14 C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO 2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with 14 C-TCE. Transport experiments showed that MnO 4 − alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO 2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO 4 − , the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP + MnO 4 − improved TCE destruction by ∼16% over MnO 4 − alone (56.5% vs. 40.1%). These results support

The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?

Directory of Open Access Journals (Sweden)

Gerry K. Schwalfenberg

2012-01-01

Full Text Available This review looks at the role of an alkaline diet in health. Pubmed was searched looking for articles on pH, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine.

Cyanobacterial Treatment Options: Permanganate and ...

Science.gov (United States)

This presentation will begin with a brief overview of drinking water treatment options for cyanobacteria and their toxins. The treatment discussion will focus on the impacts of permanganate addition to suspensions of toxin-producing Microcystis aeruginosa, followed by powdered activated carbon (PAC) addition. Results will be presented that show changes in toxin concentrations, chlorophyll-a concentrations and cell membrane integrity. The EPA Small Systems Webinar Presentations allow the dissemination of the latest Agency guidance and research to a large geographically dispersed audience while minimizing taxpayer expense

Time series geophysical monitoring of permanganate injections and in situ chemical oxidation of PCE, OU1 area, Savage Superfund Site, Milford, NH, USA.

Science.gov (United States)

Harte, Philip T; Smith, Thor E; Williams, John H; Degnan, James R

2012-05-01

In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated aquifer. Therefore, monitoring tools that provide enhanced tracking capability of the injectate offer considerable benefit to guide subsequent ISCO injections. Time-series geophysical surveys were performed at a superfund site in New Hampshire, USA over a one-year period to identify temporal changes in the bulk electrical conductivity of a tetrachloroethylene (PCE; also called tetrachloroethene) contaminated, glacially deposited aquifer due to the injection of sodium permanganate. The ISCO treatment involved a series of pulse injections of sodium permanganate from multiple injection wells within a contained area of the aquifer. After the initial injection, the permanganate was allowed to disperse under ambient groundwater velocities. Time series geophysical surveys identified the downward sinking and pooling of the sodium permanganate atop of the underlying till or bedrock surface caused by density-driven flow, and the limited horizontal spread of the sodium permanganate in the shallow parts of the aquifer during this injection period. When coupled with conventional monitoring, the surveys allowed for an assessment of ISCO treatment effectiveness in targeting the PCE plume and helped target areas for subsequent treatment. Published by Elsevier B.V.

Chrono-amperometric studies in melt alkaline nitrates and chlorides

International Nuclear Information System (INIS)

Stemmelin, Jean-Claude

1969-01-01

This research thesis proposes a large overview of the electrochemical behaviour of a number of metals and alloys in melt alkaline chlorides and nitrates at various temperatures. These salts are generally pure but, in some experiments, contain humidity or gases. The author addresses and discusses all the reactions which may occur at the electrode between the salt decomposition potentials. After having recalled and commented some definitions and fundamental principles of thermodynamics and electrochemical kinetics, presented the methods (polarization curves, measurements and additional analysis), the experimental apparatus and the reference electrodes in melt salts, the author reports the results obtained with the studied melt salts, and proposes an interpretation of Log i/U curves

Electrochemical impedance spectroscopic investigation of the role of alkaline pre-treatment in corrosion resistance of a silane coating on magnesium alloy, ZE41

Energy Technology Data Exchange (ETDEWEB)

Chakraborty Banerjee, P. [Department of Chemical Engineering, Monash University, Clayton, VIC-3800 (Australia); CAST Cooperative Research Centre, Hawthorn, VIC-3122 (Australia); Singh Raman, R.K., E-mail: raman.singh@eng.monash.edu.a [Department of Chemical Engineering, Monash University, Clayton, VIC-3800 (Australia); Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC-3800 (Australia)

2011-04-15

The protective performance of the coatings of bis-1,2-(triethoxysilyl) ethane (BTSE) on ZE41 magnesium alloy with different surface pre-treatments were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 0.1 M sodium chloride solution. Electrical equivalent circuits were developed based upon hypothetical corrosion mechanisms and simulated to correspond to the experimental data. The morphology and cross section of the alloy subjected to different pre-treatments and coatings were characterized using scanning electron microscope. A specific alkaline pre-treatment of the substrate prior to the coating has been found to improve the corrosion resistance of the alloy.

Electrochemical impedance spectroscopic investigation of the role of alkaline pre-treatment in corrosion resistance of a silane coating on magnesium alloy, ZE41

International Nuclear Information System (INIS)

Chakraborty Banerjee, P.; Singh Raman, R.K.

2011-01-01

The protective performance of the coatings of bis-1,2-(triethoxysilyl) ethane (BTSE) on ZE41 magnesium alloy with different surface pre-treatments were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 0.1 M sodium chloride solution. Electrical equivalent circuits were developed based upon hypothetical corrosion mechanisms and simulated to correspond to the experimental data. The morphology and cross section of the alloy subjected to different pre-treatments and coatings were characterized using scanning electron microscope. A specific alkaline pre-treatment of the substrate prior to the coating has been found to improve the corrosion resistance of the alloy.

Evaluation of the therapeutic effect of potassium permanganate at early stages of an experimental acute infection of Flavobacterium columnare in channel catfish (Ictalurus punctatus)

Science.gov (United States)

The efficacy of potassium permanganate (KMnO4) against early stages of an experimental acute infection of Flavobacterium columnare in channel catfish (Ictalurus punctatus) was evaluated. Fish were experimentally challenged, by waterborne exposure for 2 h to F. columnare after cutaneous abrasion, an...

Technology-base research project for electrochemical storage report for 1981

Science.gov (United States)

McLarnon, F.

1982-06-01

The technology base research (TBR) project which provides the applied reseach base that supports all electrochemical energy storage applications: electric vehicles, electric load leveling, storage of solar electricity, and energy and resource conservation is described. The TBR identifies electrochemical technologies with the potential to satisfy stringent performance and economic requirements and transfer them to industry for further development and scale up. The TBR project consists of four major elements: electrochemical systems research, supporting research, electrochemical processes, and fuel cells for transportation. Activities in these four project elements during 1981 are summarized. Information is included on: iron-air batteries; aluminum-air batteries; lithium-metal sulfide cells; materials development for various batteries; and the characteristics of an NH3-air alkaline fuel cell in a vehicle.

ELECTROCHEMICAL OXIDATION OF ETHANOL USING Ni-Co-PVC COMPOSITE ELECTRODE

Directory of Open Access Journals (Sweden)

Riyanto Riyanto

2011-07-01

Full Text Available The morphological characteristics and electrochemical behavior of nickel metal foil (Ni, nickel-polyvinyl chloride (Ni-PVC and nickel-cobalt-polyvinyl chloride (Ni-Co-PVC electrodes in alkaline solution has been investigated. The morphological characteristics of the electrode surface were studied using SEM and EDS, while the electrochemical behavior of the electrodes was studied using cyclic voltammetry (CV. It was found that composite electrodes (Ni-PVC and Ni-Co-PVC have a porous, irregular and rough surface. In situ studies using electrochemical technique using those three electrodes exhibited electrochemical activity for redox system, as well as selectivity in the electrooxidation of ethanol to acetic acid. The studies also found that an electrokinetics and electrocatalytic activity behaviors of the electrodes prepared were Ni metal foil

Effect of Permanganate Preoxidation to Natural Organic Matter and Disinfection by-Products Formation Potential Removal

Science.gov (United States)

Hidayah, E. N.; Yeh, H. H.

2018-01-01

Laboratory scale experiments was conducted to examine effect of permanganate (KMnO4) peroxidation in characterizing and to remove natural organic matter (NOM) in source water. The experimental results shows that increasing permanganate dosage could decreased aromatic matter, as indicated by decreasing UV254 and SUVA value about 23% and 28%, respectively. It seems that permanganate preoxidation caused the breakdown of high molecular weight (MW) organics into low MW ones, as represented by increasing NPDOC about 10%. Further, disinfection by-products formation potential (DBPFP) in terms of trihalomethanes formation potential (THMFP) and haloacetic acid formation potential (HAAP) decreased about 15% and 23%, respectively. HAAFP removal is higher than THMFP removal and that DPBFP removal is consistent with UV254 and NPDOC removal.

Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium

International Nuclear Information System (INIS)

Brandalise, Michele

2012-01-01

In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

The crystal structures of some alkyldiaminium perchlorates, permanganates and hexachlouranates (IV)

International Nuclear Information System (INIS)

Marais, M.A.

1984-12-01

The diquaternary nitrogen cations N,N,N,N 1 ,N 1 ,N 1 -hexaalkyl-1,2-ethane-diaminium and N,N,N,N 1 ,N 1 ,N 1 -hexaalkyl-1,6-hexanediaminium (alkyl = n-octyl for example) are important potential solvent extractants for the extraction of transition metals (Co, Cu) and uranium from HCl medium. Since the alkyldiaminium skeleton constitutes the active centre in solution, the conformations of the cations in association with typical metallate counter-ions were of interest. The crystal structures of the hexachloro-uranate (IV) and permanganate salts of the hexamethyl ethanediaminium ion, as well as the hexachlorouranate (IV) and perchlorate salts of the hexamethyl hexanediaminium ion were therefore determined by X-ray crystallography. No evidence of any deformation of the cation skeleton from their previously well-established conformations were, however, found. The structures can all be understood as typical ionic salts in which the packing and structural features are dominated by the relatively large cations. In the permanganate salt of the N,N,N,N 1 ,N 1 ,N 1 -1,2-ethanediaminium cation the bridging methylene groups display an unusual type of positional disorder, for which there is only one precedent (also discovered in this laboratory). The values of the Mn-O and U-Cl bond lengths in the permanganate and hexachlorouranate ions were determined with a precision comparable to that of the most accurate values obtained so far in other salts. These distances are also in excellent agreement with previous values, and provide further confirmation for two bond lengths for which very few estimates were previously available

Characteristics of permanganate oxidation of TCE at low reagent concentrations.

Science.gov (United States)

Woo, N C; Hyun, S G; Park, W W; Lee, E S; Schwartz, F W

2009-12-01

A controlled-release technique using potassium permanganate (KMnO4) has been recently developed as a long-term and semi-passive remediation scheme for dilute groundwater plumes of chlorinated solvents such as trichloroethylene (TCE) and perchloroethylene. Batch experiments were performed to evaluate TCE removal efficiencies of a low concentration of permanganate (MnO4-) solution and to estimate the optimum dose of permanganate required to remove low levels of TCE from groundwater plumes without leaving intermediate organic forms. Experimental results indicated that when the molar ratio of [MnO4-]0/[TCE]0 was about 10, 95% of the TCE in the plume was removed within less than 90 min, and about 90% of the chloride in the organic forms was converted into inorganic ions, while the TCE removal rates and the chloride conversion rates were considerably lower when the [TCE]0/ [MnO4-]0 values were lower. These data suggested that the [MnO4-]0 and the [MnO4-]0/[TCE]0 values would have strong effects on the efficiency and completeness of TCE oxidation. Further detailed investigations of the effect of [MnO4-]0 and [MnO4-]0/[TCE]0 values on the removal efficiencies and completeness of the TCE oxidation are warranted for successful application of the controlled-release KMnO4 technique in practice.

Comparison of permanganate preoxidation and preozonation on algae containing water: cell integrity, characteristics, and chlorinated disinfection byproduct formation.

Science.gov (United States)

Xie, Pengchao; Ma, Jun; Fang, Jingyun; Guan, Yinghong; Yue, Siyang; Li, Xuchun; Chen, Liwei

2013-12-17

Aqueous suspensions of Microcystis aeruginosa were preoxidized with either ozone or permanganate and then subjected to chlorination under conditions simulating drinking water purification. The impacts of the two oxidants on the algal cells and on the subsequent production of dissolved organic matter and disinfection byproducts were investigated. Preozonation dramatically increased disinfection byproduct formation during chlorination, especially the formation of haloaldehydes, haloacetonitriles, and halonitromethanes. Preoxidation with permanganate had much less effect on disinfection byproduct formation. Preozonation destroyed algal cell walls and cell membranes to release intracellular organic matter (IOM), and less than 2.0% integrated cells were left after preozonation with the dosage as low as 0.4 mg/L. Preoxidation with permanganate mainly released organic matter adsorbed on the cells' surface without causing any damage to the cells' integrity, so the increase in byproduct formation was much less. More organic nitrogen and lower molecular weight precursors were produced in a dissolved phase after preozonation than permanganate preoxidation, which contributes to the significant increase of disinfection byproducts after preozonation. The results suggest that permanganate is a better choice than ozone for controlling algae derived pollutants and disinfection byproducts.

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate

Energy Technology Data Exchange (ETDEWEB)

Chokejaroenrat, Chanat, E-mail: chanat@sut.ac.th [Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-0531 (United States); School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Comfort, Steve, E-mail: scomfort1@unl.edu [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Sakulthaew, Chainarong, E-mail: cvtcns@ku.ac.th [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Department of Veterinary Technology, Kasetsart University, Bangkok 10900 (Thailand); Dvorak, Bruce, E-mail: bdvorak1@unl.edu [Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-0531 (United States)

2014-03-01

Graphical abstract: - Highlights: • Transport experiments used transmissive and low permeability zones (LPZs). • {sup 14}C-labeled TCE was used to quantify oxidation of DNAPL in LPZs by permanganate. • Stabilization aids prevented MnO{sub 2} rind formation. • DNAPL oxidation improved when xanthan and stabilization aids were used. - Abstract: Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO{sub 4}{sup −}) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase {sup 14}C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO{sub 2} rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with {sup 14}C-TCE. Transport experiments showed that MnO{sub 4}{sup −} alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO{sub 2} rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO{sub 4}{sup −}, the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP + MnO{sub 4}{sup −} improved TCE destruction by �

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate.

Science.gov (United States)

Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

2014-03-15

Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO4(-)) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase (14)C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with (14)C-TCE. Transport experiments showed that MnO4(-) alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO4(-), the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP+MnO4(-) improved TCE destruction by ∼16% over MnO4(-) alone (56.5% vs. 40.1%). These results support combining permanganate with SHMP or SHMP and xanthan as a means of treating high concentrations of TCE in low permeable zones. Copyright © 2014 Elsevier B.V. All rights reserved.

Gas Generation during Sodium Permanganate Addition to HB-Line Phase II Filtrate Tank

International Nuclear Information System (INIS)

Hill, B.C.

2002-01-01

HB-Line Phase II process requires the addition of sodium permanganate followed by a sodium nitrite addition to prevent the precipitation of plutonium solids in a non-geometrically safe vessel. Previous experimental work has shown this method effective. Current concerns are related to the gas generated by the reaction. Potential difficulties include tank over-pressurization and tank overflow due to foaming or eructation. It is also necessary to verify that the quantity of permanganate specified by the facility is sufficient to reach the desired endpoint in a single addition

Topical 5% potassium permanganate solution accelerates the healing process in chronic diabetic foot ulcers.

Science.gov (United States)

Delgado-Enciso, Iván; Madrigal-Perez, Violeta M; Lara-Esqueda, Agustin; Diaz-Sanchez, Martha G; Guzman-Esquivel, Jose; Rosas-Vizcaino, Luis E; Virgen-Jimenez, Oscar O; Kleiman-Trujillo, Juleny; Lagarda-Canales, Maria R; Ceja-Espiritu, Gabriel; Rangel-Salgado, Viridiana; Lopez-Lemus, Uriel A; Delgado-Enciso, Josuel; Lara-Basulto, Agustin D; Soriano Hernández, Alejandro D

2018-02-01

Potassium permanganate has been reported to be an effective treatment for certain types of wounds. The aim of the present study was to evaluate the use of potassium permanganate in the treatment of diabetic foot ulcers. A single-blind, randomized, controlled clinical trial was conducted on patients with type 2 diabetes mellitus that presented with a foot ulcer persisting for >3 months. The control group (n=10) was treated with the current standard treatment, which comprises of measures for reducing pressure in the ulcerated area, daily cleansing of the ulcer with potable water and antiseptic wash solution, and the application of a disinfectant solution on the entire surface area of the ulcer; while the intervention group (n=15) received the standard treatment plus 5% topical potassium permanganate solution applied once a day for 21 days. In the intervention group, 1 patient did not tolerate the treatment and was eliminated from the study on the first day. The remaining patients tolerated the interventions well. At the end of the treatment period, ulcers in the control group had decreased by 38% whereas those in the intervention group decreased by 73% (Ppermanganate is well tolerated and significantly accelerates the healing process of diabetic foot ulcers.

Oxidation kinetics of polycyclic aromatic hydrocarbons by permanganate.

Science.gov (United States)

Forsey, Steven P; Thomson, Neil R; Barker, James F

2010-04-01

The reactivity of permanganate towards polycyclic aromatics hydrocarbons (PAHs) is well known but little kinetic information is available. This study investigated the oxidation kinetics of a selected group of coal tar creosote compounds and alkylbenzenes in water using permanganate, and the correlation between compound reactivity and physical/chemical properties. The oxidation of naphthalene, phenanthrene, chrysene, 1-methylnaphthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole isopropylbenzene, ethylbenzene and methylbenzene closely followed pseudo first-order reaction kinetics. The oxidation of pyrene was initially very rapid and did not follow pseudo first-order kinetics at early times. Fluoranthene was only partially oxidized and the oxidation of anthracene was too fast to be captured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene were non-reactive under the study conditions. The oxidation rate was shown to increase with increasing number of polycyclic rings because less energy is required to overcome the aromatic character of a polycyclic ring than is required for benzene. Thus the rate of oxidation increased in the series naphthalenepermanganate. 2010 Elsevier Ltd. All rights reserved.

Application of Alkaline Ionic Liquids in the Pretreatment Process of Eucalyptus Kraft Pulping

Directory of Open Access Journals (Sweden)

Yi Hou

2016-09-01

Full Text Available In order to explore the potential application of green solvent ionic liquids (ILs in the kraft pulping process, eucalyptus wood was pretreated by [Mmim]DMP before normal pulping. The results showed that materials pretreated shortly by the ionic liquid had a higher yield and viscosity coupled with a lower potassium permanganate value and residual lignin content in the pulp, as a result of the cooking process. It was also inferred that alkaline [Mmim]DMP pretreatment could dissolve lignin effectively from fiber to result in a stronger binding force and more entangled properties. Paper tensile and burst strength were improved by about 40% and 60%, respectively. These results provide a new way for eucalyptus to be utilized in the kraft pulping process.

Chemical effects induced by dissolving γ-irradiated alkali halides in aqueous nitrate, permanganate and chromate solutions

International Nuclear Information System (INIS)

Phansalkar, V.K.; Bapat, L.; Ravishankar, D.

1982-01-01

Dissolution of γ-irradiated alkali halides in aqueous solutions of sodium nitrate, potassium permanganate and potassium chromate at neutral pH induces chemical changes leading to the formation of NO 2 - in nitrate, Mn(IV) and Cr(III) species in permanganate and chromate solutions, respectively. Further, the studies on nitrate and permanganate systems show that the amount of NO 2 - and Mn(IV) formed grows by increasing the dose of γ-irradiation of the salt and the amount of irradiated salt. Moreover, the extent of chemical changes effected by irradiated chlorides has been found to be more than that of bromides. The mesh size of the irradiated salt and the presence of scavengers like I - and methanol in the system, affects the yield of NO 2 - . (author)

Consumption of potassium permanganate by impurities in deuterium oxide

International Nuclear Information System (INIS)

Anon.

1981-01-01

The titrimetric measurement of the consumption of potassium permanganate by impurities in deuterium oxide is one of the required methods intended for use in establishing whether the deuterium oxide is of sufficient purity to meet specifications. The method includes a discussion of reagents, procedure, and calculation

Characterization of electrochemically modified polycrystalline platinum surfaces

Energy Technology Data Exchange (ETDEWEB)

Krebs, L.C.; Ishida, Takanobu.

1991-12-01

The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

Characterization of electrochemically modified polycrystalline platinum surfaces

Energy Technology Data Exchange (ETDEWEB)

Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

1991-12-01

The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 V_SCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

Coupling surfactants with permanganate for DNAPL removal : coinjection or sequential application as delivery methods

Energy Technology Data Exchange (ETDEWEB)

Dugan, P.J. [Carus Corp., Peru, IL (United States); Siegrist, R.L. [Colorado School of Mines, Golden, CO (United States); Crimi, M.L. [Clarkson Univ., Potsdam, NY (United States)

2010-07-01

This PowerPoint presentation described a study conducted to test the effectiveness of surfactant-enhanced permanganate for the remediation of dense nonaqueous phase liquids (DNAPL). When DNAPL enters the environment, it can pollute millions of gallons of ground water and create huge dissolved plumes that act as long-term sources of contamination. Surfactants were used to enhance the solubilization and mobilization of DNAPL during the remediation process. In situ chemical oxidation (ISCO) was then used to deliver oxidants into the sub-surface to destroy organic contaminants in the soil and ground water. Experimental 2-D flow-through cell studies of 72 surfactants were conducted with the permanganate to evaluate delivery methods and determine compatible co-solvents for the surfactant process. Delivery methods included co-injection and sequential application. Four compatible surfactants were found to be compatible with the permanganate. A 90 percent DNAPL remediation rate was achieved using relatively low surfactant and oxidant concentrations. tabs., figs.

Investigation of the Alkaline Electrochemical Interface and Development of Composite Metal/Metal-Oxides for Hydrogen and Oxygen Electrodes

Science.gov (United States)

Bates, Michael

Understanding the fundamentals of electrochemical interfaces will undoubtedly reveal a path forward towards a society based on clean and renewable energy. In particular, it has been proposed that hydrogen can play a major role as an energy carrier of the future. To fully utilize the clean energy potential of a hydrogen economy, it is vital to produce hydrogen via water electrolysis, thus avoiding co-production of CO2 inherent to reformate hydrogen. While significant research efforts elsewhere are focused on photo-chemical hydrogen production from water, the inherent low efficiency of this method would require a massive land-use footprint to achieve sufficient hydrogen production rates to integrate hydrogen into energy markets. Thus, this research has primarily focused on the water splitting reactions on base-metal catalysts in the alkaline environment. Development of high-performance base-metal catalysts will help move alkaline water electrolysis to the forefront of hydrogen production methods, and when paired with solar and wind energy production, represents a clean and renewable energy economy. In addition to the water electrolysis reactions, research was conducted to understand the de-activation of reversible hydrogen electrodes in the corrosive environment of the hydrogen-bromine redox flow battery. Redox flow batteries represent a promising energy storage option to overcome the intermittency challenge of wind and solar energy production methods. Optimization of modular and scalable energy storage technology will allow higher penetration of renewable wind and solar energy into the grid. In Chapter 1, an overview of renewable energy production methods and energy storage options is presented. In addition, the fundamentals of electrochemical analysis and physical characterization of the catalysts are discussed. Chapter 2 reports the development of a Ni-Cr/C electrocatalyst with unprecedented mass-activity for the hydrogen evolution reaction (HER) in alkaline

Electrochemical Oxidation and Detection of Sodium Urate in ...

African Journals Online (AJOL)

DR. MIKE HORSFALL

3 Delft University of Technology, 2600 GA Delft, The Netherlands. ABSTRACT: ... both sodium urate and mixture of urate and tartrate as a cumulative response, in alkaline media, the target ..... electrochemical oxygen demand (EOD) using a.

Acute toxicity of potassium permanganate to fingerlings of the ...

African Journals Online (AJOL)

STORAGESEVER

2008-07-18

Jul 18, 2008 ... Key words: Potassium permanganate, acute toxicity, LC50, LT50, behaviour, Clarias gariepinus, Nigeria. ... soft waters where other chemicals, such as copper sulphate, were too .... The temperature (oC) was measured by dipping a dry bulb thermo- .... (KMnO4) interferes with the respiratory mechanisms of.

Histopathological and bacterial study of skin and gill of grass carp, Ceteopharyngodon idella, (Valenciennes 1844) exposed to copper sulfate and potassium permanganate.

Science.gov (United States)

Jooyandeh, Fatemeh; Sadeghpour, Ali; Khara, Hossein; Pajand, Zabihollah

2016-09-01

The gill histology and bacterial load of skin of the grass carp juveniles were investigated in relation to various concentrations of copper sulfate and potassium permanganate. For this purpose, the sublethal doses were determined after a pre-test and then the experiment was done in five treatments (for copper sulfate: 1, 1.94, 3.71, 7.07 and 15 mg/l and for potassium permanganate: 0.25, 0.52, 1.91, 2.27 and 5 mg/l) with three replicates inside the glass aquaria. Also, one group without disinfecting product was considered as control for each experiment. The microbial and histopathological investigations were done after 96 h exposure. According to results, the lowest bacterial load (CFU/g) of skin was observed in 15 mg/l copper sulfate treatment and 0.25 mg/l potassium permanganate treatment (P permanganate. In this regard, the highest histological damages were observed in 15 mg/l copper sulfate and 5 mg/l potassium permanganate respectively. Our results showed that low dosage of potassium permanganate has best effect on reducing of bacterial load of skin with lowest adverse effects on gill tissue.

Electrochemical-metallothermic reduction of zirconium in molten salt solutions

International Nuclear Information System (INIS)

McLaughlin, D.F.; Talko, F.

1990-01-01

This patent describes a method for separating hafnium from zirconium of the type wherein a feed containing zirconium and hafnium chlorides is prepared from zirconium-hafnium chloride and the feed is introduced into a distillation column, which distillation column has a reboiler connected at the bottom and a reflux condenser connected at the top and wherein a hafnium chloride enriched stream is taken from the top of the column and a zirconium enriched chloride stream is taken from the bottom of the column. It comprises: reducing the zirconium enriched chloride stream taken from the distillation column to metal by electrochemically reducing an alkaline earth metal in a molten salt bath with the molten salt in the molten salt bath consisting essentially of a mixture of at least one alkali metal chloride and at least one alkaline earth metal chloride and zirconium chloride, with the reduced alkaline earth metal reacting with the zirconium chloride to produce zirconium metal and alkaline earth metal chloride

New phenomenon of potassium permanganate treatment effect in polymer irradiated with heavy ions

International Nuclear Information System (INIS)

Zhou Mi; Liu Yibao; Wei Qianglin; Fu Yuanyong; Ju Wei; Chen Dongfeng; Wu Zhendong; Liang Haiying

2014-01-01

Background: Nuclear track membranes offer distinct advantages over conventional membranes due to their precisely determined structure. Their pore size, shape and density can be controlled intentionally so that a membrane with the required characteristics can be produced. The track etching technology plays an important role in the production of nuclear track membranes. Purpose: The effect of potassium permanganate solution pretreatment on the etching rate for polyethylene terephthalate film (PET) is studied in this work. Methods: The conductivity method is used in this research. Under different conditions, the PET films were pretreated for 1 h, 2 h, 3 h, 4 h, 5 h and 6 h by potassium permanganate solution. 5%, 15%, 25%, 35% of 2-mol·L -1 sulfuric acid solutions were added in 0.1 mol·L -1 potassium permanganate solution. Results: Track etching rate reached a peak at 2 h, Afterwards, with the pretreatment time increasing, the track etching rate declined, and the longer of the pretreatment time, the smaller of the bulk etching rate. Half cone angle either. Adding to sulfuric solution, the experimental results show that the effect on track etching rate is small, with the amount of sulfuric acid increasing, bulk etching rate becomes larger, the same change with half cone angle. In addition, the DC voltage used in the conductivity method also has impact on the track etching rate. Conclusion: The experiment has provided a method to improve the etching rate. (authors)

Histopathological and bacterial study of Persian sturgeon fry, Acipenser persicus (Borodin, 1897) exposed to copper sulfate and potassium permanganate.

Science.gov (United States)

Moshtaghi, Batol; Khara, Hossein; Pazhan, Zabiyollah; Shenavar, Alireza

2016-09-01

Persian sturgeon frys were exposed to different concentrations of copper sulfate and potassium permanganate in order to the evaluation of their impacts on bacterial load of skin, gill and surrounding water and also the histopathological alternations of gill tissue. For this purpose, the sublethal doses were determined after a pre-test and then the experiment was done in 4 (for copper sulfate: 0.07, 0.14, 026 and 0.5 mg/l) and 5 (for potassium permanganate: 0.07, 0.14, 026, 0.5 and 1 mg/l) treatments with three replicates inside the glass aquaria. Also, one group without disinfecting drug was considered as control for each experiment. The microbial and histopathological investigations were done after 96 h exposure. According to our results, a range of histopathological alternations were observed in gills tissue including mucus coagulation and secretion, hyperplasia, lamellar necrosis, hyperplasia, lamellar adhesion, haemorrhage, thickening of secondary lamellae, hypertrophy of supporter cartilage, clubbing of gill lamellae and sliming of primary lamellae. The severity of these alternations increased with increasing of the doses of the copper sulfate and potassium permanganate. The bacterial load (CFU/g) of gill, skin and surrounding water was lower in 0.07 mg/l copper sulfate treatment and 1 mg/l potassium permanganate treatment (P permanganate have disinfecting effects on bacterial load of gill, skin and surrounding water, although this is along with some histopathological alternations. Also, it seems that the copper sulfate has higher disinfecting power than potassium permanganate.

Simultaneous removal of SO{sub 2} and NOx by microwave with potassium permanganate over zeolite

Energy Technology Data Exchange (ETDEWEB)

Zai-shan Wei; He-jingying Niu; Yong-feng Ji [Sun Yat-sen University, Guangzhou (China). School of Environmental Science and Engineering

2009-02-15

Simultaneous sulfur dioxide (SO{sub 2}) and nitrogen oxides (NOx) removal from flue gas can be achieved with high efficiency by microwave with potassium permanganate (KMnO{sub 4}) over zeolite. The experimental results showed that the microwave reactor could be used to oxidation of SO{sub 2} to sulfate with the best desulfurization efficiency of 96.8% and oxidize NOx to nitrates with the best NOx removal efficiency of 98.4%. Microwave accentuates catalytic oxidation treatment, and microwave addition can increase the SO{sub 2} and NOx removal efficiency by 7.2% and 12.2% separately. The addition of zeolite to microwave potassium permanganate increases from 16.5% to 43.5% the microwave removal efficiency for SO{sub 2}, and the NOx removal efficiency from 85.6% to 98.2%. The additional use of potassium permanganate to the microwave zeolite leads to the enhancement of SO{sub 2} removal efficiency up from 53.9% to 95%, and denitrification efficiency up from 85.6% to 98.2%. The optimal microwave power and empty bed residence time (EBRT) on simultaneous desulfurization and denitrification are 259 W and 0.357 s, respectively. SO{sub 2} and NOx were rapidly oxidized in microwave induced catalytic oxidation reaction using potassium permanganate with zeolite being the catalyst and microwave absorbent. 13 refs., 6 figs.

Stress-life interrelationships associated with alkaline fuel cells

Science.gov (United States)

Thaller, Lawrence H.; Martin, Ronald E.; Stedman, James K.

1987-01-01

A review is presented concerning the interrelationships between applied stress and the expected service life of alkaline fuel cells. Only the physical, chemical, and electrochemical phenomena that take place within the fuel cell stack portion of an overall fuel cell system will be discussed. A brief review will be given covering the significant improvements in performance and life over the past two decades as well as summarizing the more recent advances in understanding which can be used to predict the performance and life characteristics of fuel cell systems that have yet to be built.

Characterization of an anionic-exchange membranes for direct methanol alkaline fuel cells

Energy Technology Data Exchange (ETDEWEB)

Abuin, Graciela C. [Centro de Procesos Superficiales, Instituto Nacional de Tecnologia Industrial (INTI), Av. Gral. Paz 5445, B1650KNA, San Martin, Buenos Aires (Argentina); Nonjola, Patrick; Mathe, Mkhulu K. [Council for Scientific and Industrial Research (CSIR), Material Science and Manufacturing, PO Box 395, Brumeria, Pretoria 0001 (South Africa); Franceschini, Esteban A.; Izraelevitch, Federico H.; Corti, Horacio R. [Departamento de Fisica de la Materia Condensada, Comision Nacional de Energia Atomica (CNEA), Av. Gral. Paz 1499, B1650KNA, San Martin, Buenos Aires (Argentina)

2010-06-15

Ammonium quaternized polymers such as poly (arylene ether sulfones) are being developed and studied as candidates of ionomeric materials for application in alkaline fuel cells, due to their low cost and promising electrochemical properties. In this work, a quaternary ammonium polymer was synthesized by chloromethylation of a commercial polysulfone followed by amination process. Quaternized polysulfone membrane properties such us water and water-methanol uptake, electrical conductivity and Young's modulus were evaluated and compared to Nafion 117, commonly employed in direct methanol fuel cells. The anionic polysulfone membrane sorbs more water than Nafion all over the whole range of water activities, but it uptakes much less methanol as compared to Nafion. The specific conductivity of the fully hydrated polysulfone membrane equilibrated with KOH solutions at ambient temperature increases with the KOH concentration, reaching a maximum of 0.083 S cm{sup -1} for 2 M KOH, slightly less conductive than Nafion 117. The elastic modulus of the polysulfone membranes inmersed in water is similar to that reported for Nafion membranes under the same conditions. We concluded that quaternized polysulfone membrane are good candidates as electrolytes in alkaline direct methanol fuel cells. (author)

Treating a natural outbreak of columnaris in channel catfish with copper sulfate and potassium permanganate

Science.gov (United States)

An F. Columnare-exclusive epizootic occurred in fingerling channel catfish (Ictalurus punctatus) during normal tank culture practices at SNARC. Fish were transferred to the ultra low-flow system and 2.1 mg/L copper sulfate or 3 mg/L potassium permanganate was administered; an untreated control was ...

High-performance alkaline direct methanol fuel cell using a nitrogen-postdoped anode.

Science.gov (United States)

Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Bender, Guido; O'Hayre, Ryan

2014-07-01

A commercial PtRu/C catalyst postdoped with nitrogen demonstrates a significantly higher performance (~10-20% improvement) in the anode of an alkaline direct methanol fuel cell than an unmodified commercial PtRu/C catalyst control. The enhanced performance shown herein is attributed at least partially to the increased electrochemical surface area of the PtRu/C after postdoping with nitrogen. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrosynthesized Ni-Al Layered Double Hydroxide-Pt Nanoparticles as an Inorganic Nanocomposite and Potentate Anodic Material for Methanol Electrooxidation in Alkaline Media

Directory of Open Access Journals (Sweden)

Biuck Habibi

2017-04-01

Full Text Available In this study, Ni-Al layered double hydroxide (LDH-Pt nanoparticles (PtNPs as an inorganic nano-composite was electrosynthesized on the glassy carbon electrode (GCE by a facile and fast two-step electrochemical process. Structure and physicochemical properties of PtNPs/Ni-Al LDH/GCE were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry and electrochemical methods. Then, electrocatalytic and stability characterizations of the PtNPs/Ni-Al LDH/GCE for methanol oxidation in alkaline media were investigated in detail by cyclic voltammetry, chronoamperometry, and chronopotentiometry measurements. PtNPs/Ni-Al LDH/GCE exhibited higher electrocatalytic activity than PtNPs/GCE and Ni-Al LDH/GCE. Also, the resulted chronoam-perograms indicated that the PtNPs/Ni-Al LDH/GCE has a better stability. Copyright © 2017 BCREC GROUP. All rights reserved Received: 30th March 2016; Revised: 29th July 2016; Accepted: 9th September 2016 How to Cite: Habibi, B., Ghaderi, S. (2017. Electro Synthesized Ni-Al Layered Double Hydroxide-Pt Nanoparticles as an Inorganic Nanocomposite and Potentate Anodic Material for Methanol Electro-Oxidation in Alkaline Media. Bulletin of Chemical Reaction Engineering & Catalysis, 12(1: 1-13 (doi:10.9767/bcrec.12.1.460.1-13 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.460.1-13

Hot 56Mn reactions in permanganate solutions: a quasi solution state study [Paper No. NC-6

International Nuclear Information System (INIS)

Dedgaonkar, V.G.; Mitra, S.

1982-01-01

Neutron activation of aqueous solutions of transition metal and ammonium permanganates over the concentration range 1-10 -3 M has been performed. Retentions for concentrated solutions were much higher than the solid state values, and upon dilution, a limiting value of approx. 4 per cent was attained. Activation of 1-10 -1 M permanganate quasi solutions containing either alumina or a polystyrene cation exchanger allowed continuous extraction of the recoil species before their recombination. (author)

Impact of anode substrates on electrodeposited zinc over cycling in zinc-anode rechargeable alkaline batteries

International Nuclear Information System (INIS)

Wei, Xia; Desai, Divyaraj; Yadav, Gautam G.; Turney, Damon E.; Couzis, Alexander; Banerjee, Sanjoy

2016-01-01

Electrochemical behavior of Ag, Bi, Cu, Fe, Ni and Sn substrates on zinc deposition was evaluated over battery cycling by cyclic voltammetry and electrochemical impedance spectroscopy. The effect of Bi, Cu, Ni, and Sn substrates on zinc electrodeposition during battery cycling was investigated using scanning electron microscopy and X-ray diffraction. The corrosion behavior of each metal in 9 M KOH and the corrosion rates of zinc plated on each substrate were analyzed by Tafel extrapolation method from the potentiodynamic polarization curves and electrochemical impedance spectroscopy. Although the charge-transfer resistance (R_c_t) of zinc electrodeposition is lowest on Sn, Sn eventually corrodes on cycling in alkaline media. Use of Ni as a substrate causes zinc to deteriorate on account of rapid hydrogen evolution. Bi and Cu substrates are more suitable for use as current collectors in zinc-anode alkaline rechargeable batteries because of their low corrosion rate and compact zinc deposition over battery cycling.

Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

Science.gov (United States)

Megawati, Monica; Chua, Chun Kiang; Sofer, Zdenek; Klímová, Kateřina; Pumera, Martin

2017-06-21

Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.

Grain size effect in corrosion behavior of electrodeposited nanocrystalline Ni coatings in alkaline solution

International Nuclear Information System (INIS)

Wang Liping; Zhang Junyan; Gao Yan; Xue Qunji; Hu Litian; Xu Tao

2006-01-01

Effects of grain size reduction on the electrochemical corrosion behavior of nanocrystalline Ni produced by pulse electrodeposition were characterized using potentiodynamic polarization testing and electrochemical impedance spectroscopy; X-ray photoelectron spectroscopy were used to confirm the electrochemical measurements and the suggested mechanisms. The corrosion resistance of Ni coatings in alkaline solutions considerably increased as the grain size decreased from microcrystalline to nanocrystalline. The higher corrosion resistance of NC Ni may be due to the more rapid formation of continuous Ni(OH) 2 passive films compared with coarse-grained Ni coatings

High-Efficiency Artificial Photosynthesis Using a Novel Alkaline Membrane Cell

Science.gov (United States)

Narayan, Sri; Haines, Brennan; Blosiu, Julian; Marzwell, Neville

2009-01-01

A new cell designed to mimic the photosynthetic processes of plants to convert carbon dioxide into carbonaceous products and oxygen at high efficiency, has an improved configuration using a polymer membrane electrolyte and an alkaline medium. This increases efficiency of the artificial photosynthetic process, achieves high conversion rates, permits the use of inexpensive catalysts, and widens the range of products generated by this type of process. The alkaline membrane electrolyte allows for the continuous generation of sodium formate without the need for any additional separation system. The electrolyte type, pH, electrocatalyst type, and cell voltage were found to have a strong effect on the efficiency of conversion of carbon dioxide to formate. Indium electrodes were found to have higher conversion efficiency compared to lead. Bicarbonate electrolyte offers higher conversion efficiency and higher rates than water solutions saturated with carbon dioxide. pH values between 8 and 9 lead to the maximum values of efficiency. The operating cell voltage of 2.5 V, or higher, ensures conversion of the carbon dioxide to formate, although the hydrogen evolution reaction begins to compete strongly with the formate production reaction at higher cell voltages. Formate is produced at indium and lead electrodes at a conversion efficiency of 48 mg of CO2/kilojoule of energy input. This efficiency is about eight times that of natural photosynthesis in green plants. The electrochemical method of artificial photosynthesis is a promising approach for the conversion, separation and sequestration of carbon dioxide for confined environments as in space habitats, and also for carbon dioxide management in the terrestrial context. The heart of the reactor is a membrane cell fabricated from an alkaline polymer electrolyte membrane and catalyst- coated electrodes. This cell is assembled and held in compression in gold-plated hardware. The cathode side of the cell is supplied with carbon

Acute toxicity of potassium permanganate to fingerlings of the ...

African Journals Online (AJOL)

Laboratory static bioassays were conducted to determine the 96-h LC50 and the lethal levels of concentrations of the aquaculture therapeutant, potassium permanganate (KMnO4) on fingerlings (mean weight, 6.24 ± 0.15 g and mean length, 4.25 ± 0.07 cm) of the African catfish, Clarias gariepinus. A total number of one ...

Nanoporous carbon for electrochemical capacitors.

Energy Technology Data Exchange (ETDEWEB)

Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

2010-05-01

Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

Nanoporous carbon for electrochemical capacitors.

Energy Technology Data Exchange (ETDEWEB)

Overmyer, Donald L.; Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

2010-04-01

Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

Oxidising alternative species to chromium VI in zinc-galvanised steel surface treatment. Part 2. An electrochemical study

International Nuclear Information System (INIS)

Almeida, E.; Fedrizzi, L.; Diamantinio, T.C.

1998-01-01

In the first part of this work, the authors present the main results and conclusions of a morphological and chemical study carried out on zinc conversion layers (ZCLs) obtained with oxidising alternative passivation baths, that includes molybdates, permanganates, van[ates and tungstates. A good chromate-based bath was used as reference. In this second part of the work, the authors present the main results obtained on selected zinc conversion layers (ZCLs), using a.c. electrochemical impedance spectroscopy (EIS). The results obtained were correlated with the morphological and chemical data obtained with the same ZCLs in the first part of this work. Finally, it is concluded that the alternative ZCLs studied, does not seem to be as efficient as that obtained with a chromate-based passivation bath used as reference. It is believed that a better understanding of the mechanisms involved in the ZCL's formation, can be useful for studying, in the very near future, possible synergetic effects between molybdates and other chemical species. (orig.)

Gold nanorods-enhanced rhodamine B-permanganate chemiluminescence and its analytical application.

Science.gov (United States)

Hassanzadeh, Javad; Amjadi, Mohammad; Manzoori, Jamshid L; Sorouraddin, Mohammad Hossein

2013-04-15

A novel enhanced chemiluminescence system was developed by applying gold nanorods (Au NRs) as catalysts in rhodamine B-permanganate reaction. Au NRs with three different aspect ratios were synthesized by seed mediated growth method and characterized by UV-Vis spectra and transmission electron microscopy. It was demonstrated that Au NRs have much higher catalytic effect than spherical nanoparticles on rhodamine B-permanganate chemiluminescence reaction. Among various sizes of Au NRs, those with average aspect ratio of 3.0 were found to have the most remarkable catalytic activity. As an analytical application of the new chemiluminescence system, albumin as a model protein was quantified based on its interaction with NRs. Albumin binds to Au NRs active surfaces and inhibits their catalytic action and therefore decreases the intensity of chemiluminescence. This diminution effect is linearly related to the concentration of the human and bovine serum albumin over the ranges of 0.45-90 and 0.75-123 nmol L(-1), respectively with the corresponding limits of detection of 0.18 and 0.30 nmol L(-1). The method was successfully applied to the determination of albumin in human and bovine serum samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrochemical processing of high-Tc Bi (Pb)–Sr–Ca–CuO thin films

Indian Academy of Sciences (India)

The different preparative parameters such as deposition potential, deposition time were studied and optimized. These films were then oxidized electrochemically at room temperature in an alkaline (1 N KOH) solution, and also at 600°C temperature in an oxygen atmosphere. The films showed the superconducting behaviour ...

The use of potassium permanganate for eliminating smells in the purification of urban sewage. Permanganate potasico para eliminacion de olores en depuracion de aguas residuales urbanas

Energy Technology Data Exchange (ETDEWEB)

Domingo Valdes, L. (Industrial Quimica del Nalon, S.A. (Spain))

1993-03-01

Chemical oxidation is an effective way to eliminate bad odors in wastewater treatment facilities at reasonable cost. Potassium permangate is one of the strongest oxidants commercially available. Its application in wastewater treatment- simple and safe- constitutes a very effective means to remove hydrogen sulfide, the main component responsible of offensive odors, whose presence is also undesirable due to its toxic and corrosive properties. Additionally, the use of potassium permanganate has a positive effect in sludge processing. (Author)

Potentiodynamic characteristics of cadmium and silver in alkaline solutions

International Nuclear Information System (INIS)

Saidman, S.B.; Vilche, J.R.; Arvia, A.J.; Lopes Teijelo, M.

1984-01-01

The potentiodynamic and ellipsometric characteristics of cadmium and silver in alkaline solutions are studied. The phenomenology of both electrodes shows some common features which are interpreted in termo of a complex hydrated oxide anodic film structure resulting from simultaneous electrochemical and chemical reactions. The kinetics of film growth fits the predictions of nucleation and growth models. (C.L.B.) [pt

Enhanced degradation of Orange G by permanganate with the employment of iron anode.

Science.gov (United States)

Bu, Lingjun; Shi, Zhou; Zhou, Shiqing

2017-01-01

Iron anode was employed to enhance the degradation of Orange G (OG) by permanganate (EC/KMnO 4 ). Continuously generated Fe 2+ from iron anode facilitated the formation of fresh MnO 2 , which plays a role in catalyzing permanganate oxidation. The EC/KMnO 4 system also showed a better performance to remove OG than Fe 2+ /KMnO 4 , indicating the importance of in situ formed fresh MnO 2 . Besides, the effects of applied current, KMnO 4 dosage, solution pH, and natural organics were evaluated and results demonstrated that high current and oxidant dosage are favorable for OG removal. And the application of iron anode has a promoting effect on the KMnO 4 oxidation over a wide pH range (5.0-9.0), while the Fe 2+ /KMnO 4 process does not. For natural organics, its presence could inhibit OG removal due to its competitive role. And the promoting effect of OG removal by the EC/KMnO 4 process in natural water was confirmed. At last, the EC/KMnO 4 process showed a satisfying performance on the decolorization and mineralization of OG. This study provides a potential technology to enhance permanganate oxidation and broadens the knowledge of azo dye removal.

Formation of assimilable organic carbon during oxidation of natural waters with ozone, chlorine dioxide, chlorine, permanganate, and ferrate.

Science.gov (United States)

Ramseier, Maaike K; Peter, Andreas; Traber, Jacqueline; von Gunten, Urs

2011-02-01

Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Advances in the use of acidic potassium permanganate as a chemiluminescence reagent: A review

International Nuclear Information System (INIS)

Adcock, Jacqui L.; Barnett, Neil W.; Barrow, Colin J.; Francis, Paul S.

2014-01-01

Graphical abstract: -- Highlights: •Analytical applications of acidic potassium permanganate chemiluminescence. •Discussion of emitting species and light-producing reaction pathways. •Influence of enhancers such as polyphosphates, formaldehyde and sulfite. •Clinical, forensic, food science, agricultural and environmental applications. -- Abstract: We review the analytical applications of acidic potassium permanganate chemiluminescence published since our previous comprehensive review in mid-2007 to early 2013. This includes a critical evaluation of evidence for the emitting species, the influence of additives such as polyphosphates, formaldehyde, sulfite, thiosulfate, lanthanide complexes and nanoparticles, the development of a generalized reaction mechanism, and the use of this chemistry in pharmaceutical, clinical, forensic, food science, agricultural and environmental applications

Advances in the use of acidic potassium permanganate as a chemiluminescence reagent: A review

Energy Technology Data Exchange (ETDEWEB)

Adcock, Jacqui L.; Barnett, Neil W.; Barrow, Colin J.; Francis, Paul S., E-mail: psf@deakin.edu.au

2014-01-07

Graphical abstract: -- Highlights: •Analytical applications of acidic potassium permanganate chemiluminescence. •Discussion of emitting species and light-producing reaction pathways. •Influence of enhancers such as polyphosphates, formaldehyde and sulfite. •Clinical, forensic, food science, agricultural and environmental applications. -- Abstract: We review the analytical applications of acidic potassium permanganate chemiluminescence published since our previous comprehensive review in mid-2007 to early 2013. This includes a critical evaluation of evidence for the emitting species, the influence of additives such as polyphosphates, formaldehyde, sulfite, thiosulfate, lanthanide complexes and nanoparticles, the development of a generalized reaction mechanism, and the use of this chemistry in pharmaceutical, clinical, forensic, food science, agricultural and environmental applications.

Spectrophotometric assay of pioglitazone hydrochloride using permanganate in acidic and basic media

Directory of Open Access Journals (Sweden)

Kanakapura Basavaiah

2018-04-01

Full Text Available Pioglitazone hydrochloride (PGH is an oral anti-hyperglycemic agent used in the treatment of type-2 diabetes mellitus. Potassium permanganate was found to oxidize PGH both in acidic and basic conditions, based on which two simple and sensitive methods were developed for its determination in bulk sample and tablets, and validated. In the first method (indirect method, PGH was reacted with a measured excess of standard permanganate in H2SO4 medium, and the residual oxidant was determined by measuring its absorbance at 550 nm. The second method (Direct method entails treating PGH with permanganate in NaOH medium, followed by the measurement of the resulting bluish-green manganite at 610 nm. Experimental variables affecting the reactions were studied and optimized. Under optimum conditions, linear relationships with good correlation coefficients were found between absorbance and concentration in the ranges, 1.25 – 25 µg mL-1 (Indirect method and 1-12 µg mL-1 (Direct method with respective molar absorptivity values of 1.10 × 104 and 2.77 × 104 l mol-1 cm-1. The limits of detection (LOD and quantification (LOQ were 0.36 and 1.08 (Indirect method and 0.23 and 0.69 µg mL-1 (Direct method. Intra-day and inter-day precisions were satisfactory, with %RSD values of ≤2.11, and the respective accuracies were excellent with %RE values of ≤2. The methods were also validated for robustness, ruggedness and selectivity. The methods were applied to the determination of PGH in its tablets with good accuracy and precision, and no interference from the tablet additives was encountered. The results were also compared with those obtained by a reference method.

One-step electrosynthesis of ethylene and ethanol from CO2 in an alkaline electrolyzer

Science.gov (United States)

Ma, Sichao; Sadakiyo, Masaaki; Luo, Raymond; Heima, Minako; Yamauchi, Miho; Kenis, Paul J. A.

2016-01-01

Electroreduction of CO2 has potential for storing otherwise wasted intermittent renewable energy, while reducing emission of CO2 into the atmosphere. Identifying robust and efficient electrocatalysts and associated optimum operating conditions to produce hydrocarbons at high energetic efficiency (low overpotential) remains a challenge. In this study, four Cu nanoparticle catalysts of different morphology and composition (amount of surface oxide) are synthesized and their activities towards CO2 reduction are characterized in an alkaline electrolyzer. Use of catalysts with large surface roughness results in a combined Faradaic efficiency (46%) for the electroreduction of CO2 to ethylene and ethanol in combination with current densities of ∼200 mA cm-2, a 10-fold increase in performance achieved at much lower overpotential (only catalysts bring electrochemical reduction processes such as presented here closer to practical application.

Sensitive spectrophotometric assay of simvastatin in pharmaceuticals using permanganate

Directory of Open Access Journals (Sweden)

Kalsang Tharpa

2010-03-01

Full Text Available Two simple, sensitive, selective and inexpensive spectrophotometric methods are described for the determination of simvastatin (SMT in bulk drug and in tablets using permanganate as the oxidimetric reagent. In method A, SMT is treated with a measured excess of permanganate in acetic acid medium and the unreacted oxidant is measured at 550 nm, whereas in method B the reaction is carried out in alkaline medium and the resulting manganate is measured at 610 nm. In method A, the amount of permanganate reacted corresponds to the SMT content and the absorbance is found to decrease linearly with the concentration; and in method B, the absorbance increases with concentration. The working conditions of assays were optimized, and the methods were validated according to the current ICH guidelines. Under optimum conditions, SMT could be assayed in the concentration ranges, 1.47 - 17.67x10-5 and 2.27 - 27.18 x10-6 mol/L by method A and method B, respectively. The calculated molar absorptivities are 3.2 x 10³ and 2.5 x 10(4 L/mol/cm for method A and method B, respectively with corresponding Sandell sensitivity values of 0.0387 and 0.0178 μg/cm². The limits of detection (LOD and quantification (LOQ have also been reported. Accuracy and precision for the assay were determined by calculating the intra-day and inter-day at three concentrations; the intra-day RSD was Dois métodos espectrofotométricos simples, sensíveis, seletivos e baratos são descritos para a determinação de sinvastatina (SMT a granel e em comprimidos, utilizando permanganato como reagente oxidimétrico. No método A, a SMT é tratada com excesso conhecido de permanganato em meio de ácido acético e o oxidante que não reage é medido a 550 nm, enquanto no método B, a reação é efetuada em meio alcalino e o manganato resultante é medido a 610 nm. No método A, a quantidade de permanganato que reage corresponde ao conteúdo de SMT e a absorbância diminui linearmente com o aumento da

Binary Mixtures of Permanganate and Chlorinated Volatile Organic Compounds in Groundwater Samples: Sample Preservation and Analysis

Science.gov (United States)

Ground water samples collected at sites where in-situ chemical oxidation (ISCO) has been deployed may contain binary mixtures of ground water contaminants and permanganate (MnO4-), an oxidant injected into the subsurface to destroy the contaminant. Commingling of the oxidant and ...

Permanganate-assisted removal of PCR inhibitors during the DNA Chelex extraction from stained denim samples.

Science.gov (United States)

Pîrlea, Sorina; Puiu, Mihaela; Răducan, Adina; Oancea, Dumitru

2017-03-01

In this study, it was demonstrated that the DNA Chelex extraction combined with the permanganate assisted-oxidation is highly efficient in removing the PCR inhibitors often found in clothing materials, such as phthalocyanine. The extraction assays were conducted in saliva, blood and epithelial cells samples mixed with three oxidation-resistant dye copper(II) α-phthalocyanine, copper(II) β-phthalocyanine and tetrasulfonated copper(II) β-phthalocyanine. After DNA amplification, all samples were able to provide full DNA profiles. The permanganate/Chelex system was tested further on denim-stained samples and displayed the same ability to remove the PCR inhibitors from the commercial textile materials.

Bussing Structure In An Electrochemical Cell

Science.gov (United States)

Romero, Antonio L.

2001-06-12

A bussing structure for bussing current within an electrochemical cell. The bussing structure includes a first plate and a second plate, each having a central aperture therein. Current collection tabs, extending from an electrode stack in the electrochemical cell, extend through the central aperture in the first plate, and are then sandwiched between the first plate and second plate. The second plate is then connected to a terminal on the outside of the case of the electrochemical cell. Each of the first and second plates includes a second aperture which is positioned beneath a safety vent in the case of the electrochemical cell to promote turbulent flow of gasses through the vent upon its opening. The second plate also includes protrusions for spacing the bussing structure from the case, as well as plateaus for connecting the bussing structure to the terminal on the case of the electrochemical cell.

Kinetics and selectivity of permanganate chemiluminescence: a study of hydroxyl and amino disubstituted benzene positional isomers.

Science.gov (United States)

Slezak, Teo; Smith, Zoe M; Adcock, Jacqui L; Hindson, Christopher M; Barnett, Neil W; Nesterenko, Pavel N; Francis, Paul S

2011-11-30

Examination of the chemiluminescence reactions of dihydroxybenzenes, aminophenols and phenylenediamines with acidic potassium permanganate has provided a new understanding of the relationships between analyte structure, reaction conditions, kinetics of the light-producing pathway and emission intensity, with broad implications for this widely utilised chemiluminescence detection system. Using a permanganate reagent prepared in a polyphosphate solution and adjusted to pH 2.5, large differences in the rate of reaction with different positional isomers were observed, with the meta-substituted forms reacting far slower and therefore exhibiting much lower chemiluminescence intensities in flow analysis systems. The preliminary partial reduction of permanganate to form significant concentrations of Mn(III) increased the rate of reaction with all analytes tested, resulting in comparable or (in the case of aminophenol and phenylenediamine) even greater emission intensities for the meta-isomers, demonstrating the opportunity to tune the selectivity of the reagent towards certain classes of compound or even specific positional isomers of the same compound. Using more acidic permanganate reagents, in which polyphosphates are not required, the discrepancy between the chemiluminescence intensities was still observed, but was less prominent due to the generally faster rates of reaction. The enhancement of these chemiluminescence reactions by on-line addition of formic acid or formaldehyde can in part also be attributed to the generation of significant pools of the key Mn(III) precursor to the emitting species. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of the kinetic oxidation of aqueous volatile organic compounds by permanganate.

Science.gov (United States)

Mahmoodlu, Mojtaba G; Hassanizadeh, S Majid; Hartog, Niels

2014-07-01

The use of permanganate solutions for in-situ chemical oxidation (ISCO) is a well-established groundwater remediation technology, particularly for targeting chlorinated ethenes. The kinetics of oxidation reactions is an important ISCO remediation design aspect that affects the efficiency and oxidant persistence. The overall rate of the ISCO reaction between oxidant and contaminant is typically described using a second-order kinetic model while the second-order rate constant is determined experimentally by means of a pseudo first order approach. However, earlier studies of chlorinated hydrocarbons have yielded a wide range of values for the second-order rate constants. Also, there is limited insight in the kinetics of permanganate reactions with fuel-derived groundwater contaminants such as toluene and ethanol. In this study, batch experiments were carried out to investigate and compare the oxidation kinetics of aqueous trichloroethylene (TCE), ethanol, and toluene in an aqueous potassium permanganate solution. The overall second-order rate constants were determined directly by fitting a second-order model to the data, instead of typically using the pseudo-first-order approach. The second-order reaction rate constants (M(-1) s(-1)) for TCE, toluene, and ethanol were 8.0×10(-1), 2.5×10(-4), and 6.5×10(-4), respectively. Results showed that the inappropriate use of the pseudo-first-order approach in several previous studies produced biased estimates of the second-order rate constants. In our study, this error was expressed as a function of the extent (P/N) in which the reactant concentrations deviated from the stoichiometric ratio of each oxidation reaction. The error associated with the inappropriate use of the pseudo-first-order approach is negatively correlated with the P/N ratio and reached up to 25% of the estimated second-order rate constant in some previous studies of TCE oxidation. Based on our results, a similar relation is valid for the other volatile

Simultaneous removal of SO{sub 2} and NO{sub x} by microwave with potassium permanganate over zeolite

Energy Technology Data Exchange (ETDEWEB)

Wei, Zai-shan; Niu, He-jingying; Ji, Yong-feng [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

2009-02-15

Simultaneous sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) removal from flue gas can be achieved with high efficiency by microwave with potassium permanganate (KMnO{sub 4}) over zeolite. The experimental results showed that the microwave reactor could be used to oxidation of SO{sub 2} to sulfate with the best desulfurization efficiency of 96.8% and oxidize NO{sub x} to nitrates with the best NO{sub x} removal efficiency of 98.4%. Microwave accentuates catalytic oxidation treatment, and microwave addition can increase the SO{sub 2} and NO{sub x} removal efficiency by 7.2% and 12.2% separately. The addition of zeolite to microwave potassium permanganate increases from 16.5% to 43.5% the microwave removal efficiency for SO{sub 2}, and the NO{sub x} removal efficiency from 85.6% to 98.2%. The additional use of potassium permanganate to the microwave zeolite leads to the enhancement of SO{sub 2} removal efficiency up from 53.9% to 95%, and denitrification efficiency up from 85.6% to 98.2%. The optimal microwave power and empty bed residence time (EBRT) on simultaneous desulfurization and denitrification are 259 W and 0.357 s, respectively. SO{sub 2} and NO{sub x} were rapidly oxidized in microwave induced catalytic oxidation reaction using potassium permanganate with zeolite being the catalyst and microwave absorbent. (author)

A simple model of the batch electrochemical reduction of nitrate/nitrite waste

International Nuclear Information System (INIS)

Wingard, D.A.; Weidner, J.W.; Van Zee, J.W.

1994-01-01

A model of a divided parallel plate electrochemical cell operated in a batch mode for the destruction of NO 3 - /NO 2 - in alkaline waste streams is presented. The model uses boundary layer approximations at each electrode and at the separator to minimize computation time. Five competing electrochemical reactions are included at the cathode. The model uses either an explicit Runge-Kutta routine with empirically determined current efficiencies or an implicit stepping routine for each electrode if the current efficiencies are to be predicted. Tim dependent changes of the concentration, temperature, and cell voltage are predicted for constant current operation. Model predictions are compared with experimental data

Three Rate-Constant Kinetic Model for Permanganate Reactions Autocatalyzed by Colloidal Manganese Dioxide: The Oxidation of L-Phenylalanine.

Science.gov (United States)

Perez-Benito, Joaquin F; Ferrando, Jordi

2014-12-26

The reduction of permanganate ion to MnO(2)-Mn(2)O(3) soluble colloidal mixed oxide by l-phenylalanine in aqueous phosphate-buffered neutral solutions has been followed by a spectrophotometric method, monitoring the decay of permanganate ion at 525 nm and the formation of the colloidal oxide at 420 nm. The reaction is autocatalyzed by the manganese product, and three rate constants have been required to fit the experimental absorbance-time kinetic data. The reaction shows base catalysis, and the values of the activation parameters at different pHs have been determined. A mechanism including both the nonautocatalytic and the autocatalytic reaction pathways, and in agreement with the available experimental data, has been proposed. Some key features of this mechanism are the following: (i) of the two predominant forms of the amino acid, the anionic form exhibits a stronger reducing power than the zwitterionic form; (ii) the nonautocatalytic reaction pathway starts with the transfer of the hydrogen atom in the α position of the amino acid to permanganate ion; and (iii) the autocatalytic reaction pathway involves the reduction of Mn(IV) to Mn(II) by the amino acid and the posterior reoxidation of Mn(II) to Mn(IV) by permanganate ion.

Comparison of anti-corrosive properties between hot alkaline nitrate blackening and hydrothermal blackening routes

Energy Technology Data Exchange (ETDEWEB)

Fattah-alhosseini, A. [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Yazdani Khan, H., E-mail: hamid.yazdanikhan@gmail.com [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Heidarpour, A. [Department of Metallurgy and Materials Engineering, Hamedan University of Technology, Hamedan, 65155-579 (Iran, Islamic Republic of)

2016-08-15

In this study, the oxide films were formed on carbon steel by using hot alkaline nitrate and hydrothermal treatments. A dense and protective oxide film was obtained by hydrothermal method due to application of high pressure and by increasing solution temperature from boiling temperature (155 °C) to 250 °C. Oxide films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical tests including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). These analyses showed that the magnetite film which was formed on carbon steel surface by hydrothermal treatment offers the best resistance in 3.5 wt.% NaCl solution. Although thicker oxide film could be obtained via hot alkaline nitrate black oxidizing, corrosion resistance was lower as a result of being highly porous and the presence of hematite. - Highlights: • Oxide films have been formed on steel by using of hot alkaline nitrate and hydrothermal treatments. • A dense and protective oxide film was obtained by hydrothermal treatment. • SEM micrographs showed that a dense and protective oxide film was obtained by hydrothermal treatment. • Film formed by hydrothermal treatment could have the best resistance in 3.5 wt.% NaCl solution.

Electrochemical behavior of meso-substituted iron porphyrins in alkaline aqueous media

Science.gov (United States)

Berezina, N. M.; Bazanov, M. I.; Maksimova, A. A.; Semeikin, A. S.

2017-12-01

The effect meso-substitution in iron porphyrin complexes has on their redox behavior in alkaline aqueous solutions is studied via cyclic voltammetry. The voltammetric features of the reduction of iron pyridylporphyrins suggest that the sites of electron transfer lie at the ligand, the metal ion, and the pyridyl moieties. The electron transfer reactions between the different forms of these compounds, including the oxygen reduction reaction they mediate, are outlined to show the sequence and potential ranges in which they occur in alkaline aqueous media. Under our experimental conditions, the iron porphyrins exist as μ-oxo dimmers whose activity for the electrocatalytic reduction of oxygen displays a considerable dependence on the nature of the substitutents and nitrogen isomerization (for pyridylporphyrins) and grows in the order (Fe( ms-Ph)4P)2O, (Fe[ ms-(Py-3)Ph3]P)2O, (Fe[ ms-(Py-4)4]P)2O, and (Fe[ ms-(Py-3)4]P)2O.

Fast and efficient green synthesis of thiosulfonate S-esters by microwave-supported permanganate oxidation of symmetrical disulfides

DEFF Research Database (Denmark)

Thi, Luu Thi Xuan; Thi Nguyen, Thao-Tran; Le, Thach Ngoc

2015-01-01

Potassium permanganate absorbed on copper(II) sulfate pentahydrate has been found to be an efficient, inexpensive, and green oxidation agent for the synthesis of “symmetrical” thiosulfonate S-esters by oxidation of the corresponding symmetrical disulfides. The oxidation reactions were carried out...

Electrochemical cell structure including an ionomeric barrier

Science.gov (United States)

Lambert, Timothy N.; Hibbs, Michael

2017-06-20

An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

Reaction of iodine oxidation by potassium permanganate in tributyl phosphate

International Nuclear Information System (INIS)

Khokhlov, M.L.; Legin, E.K.

1990-01-01

Stoichiometry was determined and kinetics of iodine oxidation by potassium permanganate in tributylphosphate was studied. Kinetic scheme, which agrees with stoichiometry and experimental kinetic equation of the reaction, is suggested. A mixture is the reaction product. It is ascertained that when the mixture is heated, thermal decomposition of iodate to iodide occurs without elementary iodine separation, which is catalyzed by polymanganate

Experimental and analytical analysis of polarization and water transport behaviors of hydrogen alkaline membrane fuel cell

Science.gov (United States)

Huo, Sen; Zhou, Jiaxun; Wang, Tianyou; Chen, Rui; Jiao, Kui

2018-04-01

Experimental test and analytical modeling are conducted to investigate the operating behavior of an alkaline electrolyte membrane (AEM) fuel cell fed by H2/air (or O2) and explore the effect of various operating pressures on the water transfer mechanism. According to the experimental test, the cell performance is greatly improved through increasing the operating pressure gradient from anode to cathode which leads to significant liquid water permeation through the membrane. The high frequency resistance of the A901 alkaline membrane is observed to be relatively stable as the operating pressure varies based on the electrochemical impedance spectroscopy (EIS) method. Correspondingly, based on the modeling prediction, the averaged water content in the membrane electrode assembly (MEA) does not change too much which leads to the weak variation of membrane ohmic resistance. This reveals that the performance enhancement should give the credit to better electro-chemical reaction kinetics for both the anode and cathode, also prone by the EIS results. The reversion of water back diffusion direction across the membrane is also observed through analytical solution.

Alkaline-Acid Zn-H2 O Fuel Cell for the Simultaneous Generation of Hydrogen and Electricity.

Science.gov (United States)

Cai, Pingwei; Li, Yan; Wang, Genxiang; Wen, Zhenhai

2018-04-03

An alkaline-acid Zn-H 2 O fuel cell is proposed for the simultaneous generation of electricity with an open circuit voltage of about 1.25 V and production of H 2 with almost 100 % Faradic efficiency. We demonstrate that, as a result of harvesting energy from both electrochemical neutralization and electrochemical Zn oxidation, the as-developed hybrid cell can deliver a power density of up to 80 mW cm -2 and an energy density of 934 Wh kg -1 and maintain long-term stability for H 2 production with an output voltage of 1.16 V at a current density of 10 mA cm -2 . © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An electrochemical analysis of AZ91 Mg alloy processed by plasma electrolytic oxidation followed by static annealing

Energy Technology Data Exchange (ETDEWEB)

Ko, Y.G. [School of Materials Science and Engineering, Yeungnam University, 214-1 Dae-Dong, Gyeongsan 712-749, Gyeongbuk (Korea, Republic of); Lee, K.M.; Lee, B.U. [Department of Metallurgy and Materials Engineering, Hanyang University, Ansan 425-791 (Korea, Republic of); Shin, D.H., E-mail: dhshin@hanyang.ac.kr [Department of Metallurgy and Materials Engineering, Hanyang University, Ansan 425-791 (Korea, Republic of)

2011-06-15

Research highlights: > The amount of MgO in the oxide film increased with increasing annealing temperature. > The dehydration reaction resulted in the formation of micro-cracks in the oxide film. > Electrochemical response of the PEO-treated sample annealed at 150 deg. C was improved. - Abstract: In this study, the effect of subsequent annealing on the electrochemical response of AZ91 Mg alloy coated via plasma electrolytic oxidation (PEO) was investigated. PEO coating was carried out on the Mg alloy under AC condition in an alkaline silicate electrolyte, and the PEO-coated samples underwent several subsequent annealing treatments at three different temperatures of 100, 150, and 200 deg. C. The surface morphologies of the coating layers were observed via a scanning electron microscope (SEM) and their constituent compounds were characterized by qualitative observation based on X-ray photoelectron spectroscopy (XPS). In addition, the corrosion protection properties of the PEO-coated sample were examined by electrochemical impedance spectroscopy (EIS) in a 3.5 wt% NaCl solution with a focus on exploring the effect of subsequent annealing on the electrochemical response in a quantitative manner. SEM and XPS observations evidenced that the subsequent annealing at temperatures higher than 150 deg. C resulted in significant morphological changes due to the dehydration reaction of Mg(OH){sub 2} to form MgO. Thus, it was found that the sample annealed at 150 deg. C exhibited a better corrosion resistance than the other samples, which were analyzed by taking an equivalent circuit model into account.

Decontamination by water jet, chemical and electrochemical methods

International Nuclear Information System (INIS)

Gauchon, J.P.; Mordenti, P.; Bezia, C.; Fuentes, P.; Kervegant, Y.; Munoz, C.; Pierlas, C.

1986-01-01

The decontamination tests have been carried out on samples coming from representative specimens from primary circuit of the PWR and on samples coming from the emergency feed water piping of the German BWR (Isar). The oxide found in PWR primary loops can only be removed by a two steps process. The initial embrittling step is particularly effective in hot alkaline permanganate medium. Oxidation by ozone treatment is less effective. The second step involves chemical erosion of the metal in nitrofluoric acid in conjonction with ultrasonic agitation. Among the reagents used, only oxalic acid is suitable for electrolytic decontamination. Among the reagents possible for decontamination of the Isar specimens (ferritic steel lined with hematite) halogenous acid in mixture without or with oxygenated water, sulfuric acid, the formic acid/formaldehyde mixture are chosen. Metal erosion with high pressure jet as well as the decontamination efficiency on parts lined with hematite have made possible to determine the best conditions. 33 figs, 29 refs

Potassium permanganate in drinking water treatment: reduction of organic matter and disinfection by-products; Permanganato potasico en potabilizacion de aguas : Reduccion de materias organicas y subproductos de desinfeccion

Energy Technology Data Exchange (ETDEWEB)

Marin Galvin, R. [Universidad de Cordoba (Spain)

1997-09-01

This paper deals on the results obtained with the use of potassium permanganate (KMnO{sub 4}) in drinking water treatment. Thus, permanganization of water before chlorination implied the reduction of 50% in odors. Moreover, oxidation with KMnO{sub 4} reduced UV absorbency of water (UV-254nm) by a 17% more as compared with that obtained by chlorine. Finally as far as the production of organo-chlorinated compounds, the treatment with (potassium permanganate+chlorine) allowed an important reduction vs the conventional chlorination: only a 65% of total THMs were generated (between 58% and 80% of specific THM) and between 30 % and 68% of tri-and tetra-phenolchlorinated, as compared with only chlorination. (Author)

Estimation of the nitric oxide formed from hydroxylamine by Nitrosomonas

Science.gov (United States)

Anderson, J. H.

1965-01-01

1. Nitric oxide that was produced by reducing nitrite with an excess of acidified potassium iodide under nitrogen in Warburg respirometer flasks was rapidly absorbed by a solution of permanganate in sodium hydroxide held in the side arm. A small amount of nitrous oxide (or nitrogen) that was also produced was not absorbed. 2. By using a quantitative method for the recovery of nitrite from samples of the alkaline permanganate, it was found that the sum of the nitrite N formed and the residual nitrous oxide N was equivalent to the nitrite N used to generate the gases. These results showed that alkaline permanganate completely oxidized nitric oxide to nitrite. The method was suitable for determining 0·4–20 μmoles of nitric oxide. 3. The technique was used to determine the nitric oxide content of the nitrogenous gas that was produced anaerobically from hydroxylamine by an extract of the autotrophic nitrifying micro-organism Nitrosomonas in the presence of methylene blue as electron acceptor. PMID:14342235

Assessing ocean alkalinity for carbon sequestration

Science.gov (United States)

Renforth, Phil; Henderson, Gideon

2017-09-01

Over the coming century humanity may need to find reservoirs to store several trillions of tons of carbon dioxide (CO2) emitted from fossil fuel combustion, which would otherwise cause dangerous climate change if it were left in the atmosphere. Carbon storage in the ocean as bicarbonate ions (by increasing ocean alkalinity) has received very little attention. Yet recent work suggests sufficient capacity to sequester copious quantities of CO2. It may be possible to sequester hundreds of billions to trillions of tons of C without surpassing postindustrial average carbonate saturation states in the surface ocean. When globally distributed, the impact of elevated alkalinity is potentially small and may help ameliorate the effects of ocean acidification. However, the local impact around addition sites may be more acute but is specific to the mineral and technology. The alkalinity of the ocean increases naturally because of rock weathering in which >1.5 mol of carbon are removed from the atmosphere for every mole of magnesium or calcium dissolved from silicate minerals (e.g., wollastonite, olivine, and anorthite) and 0.5 mol for carbonate minerals (e.g., calcite and dolomite). These processes are responsible for naturally sequestering 0.5 billion tons of CO2 per year. Alkalinity is reduced in the ocean through carbonate mineral precipitation, which is almost exclusively formed from biological activity. Most of the previous work on the biological response to changes in carbonate chemistry have focused on acidifying conditions. More research is required to understand carbonate precipitation at elevated alkalinity to constrain the longevity of carbon storage. A range of technologies have been proposed to increase ocean alkalinity (accelerated weathering of limestone, enhanced weathering, electrochemical promoted weathering, and ocean liming), the cost of which may be comparable to alternative carbon sequestration proposals (e.g., $20-100 tCO2-1). There are still many

Permanganate Treatment of Savannah River Site Simulant Wastes for Strontium and Actinide Removal

International Nuclear Information System (INIS)

Wilmarth, W.R.

2003-01-01

This study examined the use of sodium permanganate and strontium nitrate to remove the actinides and radio-strontium from Savannah River Site (SRS) waste supernate. We examined the quantities of chemical feed reagents along with increased mixing and the excess of organic reductant. Additionally, we examined two processing schemes including that applicable to either the Salt Waste Processing Facility or the Alpha Removal Process (ARP) (5.6 M sodium ion concentration) conditions and the conditions for an In-Tank application (7.5 M sodium ion concentration). Our results support the following conclusions: The process met minimum required decontamination factors (DFs) within the tested parameter sets for strontium and plutonium in both the ARP and In-Tank application. The strontium DFs far exceeded the required values within the tested parameter sets. Within the ARP application, the use of peroxide as the reductant for permanganate produced higher plutonium DFs than the use of sodium formate. Reductant concentration and degree of mixing strongly influenced radionuclide decontamination. In the formate application under the ARP process, increasing the reductant concentration and mixing energy resulted in higher Sr and Pu decontamination

To postpone the precipitation of manganese oxides in the degradation of tetrachloroethylene by controlling the permanganate concentration.

Science.gov (United States)

Yang, Weiwei; Qiu, Zhaofu; Zhao, Zhexuan; Lu, Shuguang; Sui, Qian; Gu, Xiaogang

2017-01-01

Controlled-release permanganate (CRP) is a relatively new technology used to treat contaminated groundwater. This study tested the encapsulation of permanganate using stearic acid to realize controlled-release properties. Batch experiments were conducted to investigate the performance of manganese oxides (MnO 2 ) in the reaction between CRP and the contaminant of interest: tetrachloroethylene (PCE). The results showed that higher ionic strengths (I = 0.1 mol/L) cause earlier precipitation of MnO 2 colloids. Using CRP to degrade PCE could decrease the amount of MnO 2 colloids produced and postpone precipitation compared to raw potassium permanganate (KMnO 4 ) under high ionic strength conditions by controlling the KMnO 4 concentration in the solution. The amount of MnO 2 colloids produced and the time of precipitation depended more on the CRP grain size than on the CRP mass ratio. Controlling the KMnO 4 concentration used in the reaction could control the formation of MnO 2 precipitates in the premise of guarantee the removal rate of PCE.

Electrochemical and in-situ Surface-Enhanced Raman Spectroscopic (SERS) study of passive films formed on low-carbon steel in highly alkaline environments

Science.gov (United States)

Mancio, Mauricio

In reinforced concrete, a passive layer forms because of the alkaline conditions in the pores of the cement paste, where large concentrations of hydroxides create a solution with pH typically between 12 and 14. The corrosion resistance of the material depends on the characteristics and integrity of the passive film; however, currently very limited information is available about the passive films formed on carbon steel under such conditions. This work presents an electrochemical and in-situ Surface-Enhanced Raman Spectroscopic (SERS) study of passive films formed on low-carbon steel in highly alkaline environments. More specifically, the study focuses on the characterization of the films formed on ASTM A36 steel reinforcing bar exposed to aqueous solutions that aim to reproduce the chemistry of the environment typically found within the cement paste. Electrochemical techniques such as cyclic potentiodynamic polarization curves, galvanostatic cathodic polarization and linear polarization resistance were employed, in addition to in-situ Surface Enhanced Raman Spectroscopy (SERS). The experimental setup was built in a way that SERS experiments could be performed simultaneously with potentiodynamic polarization curves, enabling a detailed analysis of the formation and reduction of the surface films as a function of applied potential. Three solutions with different pH levels were used for the polarization and SERS experiments, namely 0.55M KOH + 0.16M NaOH ([OH-]=0.71), 0.08M KOH + 0.02M NaOH ([OH-]=0.10) and 0.008M KOH + 0.002M NaOH ([OH-]=0.01). Additional NaOH solutions in which the pH was varied from 13 to 9 and the ionic strength from 10 -5 to 10-1 were prepared for a pilot study using linear polarization resistance. Results show that the features observed in the cyclic potentiodynamic polarization curves correlated well with the potential arrests observed in the GCP plots as well as with the changes observed in the SERS spectra, providing valuable information about

BENCH-SCALE VISUALIZATION OF DNAPL REMEDIATION PROCESSES IN ANALOG HETEROGENEOUS AQUIFERS: SURFACTANT FLOODS, AND IN SITU OXIDATION USING PERMANGANATE

Science.gov (United States)

We have conducted well-controlled DNAPL remediation experiments using surfactants (Aerosol MA and Tween 80) to increase solubility and an oxidant (permanganate) to chemically degrade the DNAPL. Photographs and digital image analysis illustrate previously unobserved interactions b...

Preparation of anionic clay–birnessite manganese oxide composites by interlayer oxidation of oxalate ions by permanganate

International Nuclear Information System (INIS)

Arulraj, James; Rajamathi, Michael

2013-01-01

Oxalate intercalated anionic clay-like nickel zinc hydroxysalt was obtained starting from nickel zinc hydroxyacetate, Ni 3 Zn 2 (OH) 8 (OAc) 2 ·2H 2 O, by anion exchange. The intercalated oxalate species was reacted with potassium permanganate in such a way that the layered manganese oxide formed was within the interlayer region of the anionic clay resulting in a layered composite in which the negative charges on the birnessite type manganese oxide layers compensate the positive charges on the anionic clay layers. Birnessite to anionic clay ratio could be varied by varying the reaction time or the amount of potassium permanganate used. - Graphical abstract: Nickel zinc hydroxyoxalate was reacted with potassium permanganate to get nickel zinc hydroxide birnessite composites in which the positive charges on the hydroxide layers are neutralized by the negative charges on birnessite layers. Highlights: ► Anionic and cationic layered solid composites prepared. ► Ni–Zn hydroxyoxalate reacted with KMnO 4 to deposit MnO 2 in the interlayer. ► Birnessite layers coexist with anionic clay layers in the composites. ► Birnessite/anionic clay ratio controlled by amount of KMnO 4 used and reaction time

Modification of radiation-induced oxic and anoxic damage by caffeine and potassium permanganate in barley seeds

International Nuclear Information System (INIS)

Kesavan, P.C.; Dodd, N.J.F.

1976-01-01

It has been demonstrated that both the immediate and post-irradiation oxygen effects in barley seeds decrease in magnitude in the presence of potassium permanganate and caffeine. This implied that these two types of oxygen effect have features in common. With the removal of the radiation-induced oxygen-sensitive sites, by anoxic hydration, caffeine potentiated the oxygen-independent component of damage, in seeds irradiated in a dry or pre-soaked state. Potassium permanganate, on the other hand, enhanced the anoxic radiation damage only in seeds irradiated in a dry state. The possible mode of action of KMnO 4 and caffeine in barley seeds is discussed. (author)

[Study of relationship between consumption of potassium permanganate and total organic carbon on plastic kitchen utensils, food packages and toys].

Science.gov (United States)

Ohno, Hiroyuki; Suzuki, Masako; Mutsuga, Motoh; Kawamura, Yoko

2009-10-01

Consumption of potassium permanganate and total organic carbon (TOC) were investigated as indices of total organic matter migrated into water from plastic kitchen utensils, food packages and toys for children. The samples were soaked in water at 60 or 95 degrees C for 30 min for kitchen utensils and food packages, and at 40 degrees C for 30 min for toys and the eluates were examined, using the two indices. The quantitation limits were both 0.5 microg/mL. Among 97 kitchen utensils and food packages tested, consumption of potassium permanganate and TOC were 0.5-10.9 microg/mL and ND-18.9 microg/mL for polyvinyl chloride (PVC) tea-pot spouts and nylon kitchen utensils, respectively. Among 32 toys tested, the levels were 0.8-45.5 microg/mL and 0.5-8.9 microg/mL from PVC toys and block toys made by ethylene vinyl acetate resin. The levels for other samples were very low. There were large discrepancies between consumption of potassium permanganate and TOC for some PVC products and nylon kitchen utensils. The cause may be a marked difference of the oxidation decomposition rate by potassium permanganate, depending on the kind of organic matter that migrated from the plastics.

ADVANTAGES/DISADVANTAGES FOR ISCO METHODS IN-SITU FENTON OXIDATION IN-SITU PERMANGANATE OXIDATION

Science.gov (United States)

The advantages and disadvantages of in-situ Fenton oxidation and in-situ permanganate oxidation will be presented. This presentation will provide a brief overview of each technology and a detailed analysis of the advantages and disadvantages of each technology. Included in the ...

Safety of an alkalinizing buffer designed for inhaled medications in humans.

Science.gov (United States)

Davis, Michael D; Walsh, Brian K; Dwyer, Scott T; Combs, Casey; Vehse, Nico; Paget-Brown, Alix; Pajewski, Thomas; Hunt, John F

2013-07-01

Airway acidification plays a role in disorders of the pulmonary tract. We hypothesized that the inhalation of alkalinized glycine buffer would measurably alkalinize the airways without compromising lung function or causing adverse events. We evaluated the safety of an inhaled alkaline glycine buffer in both healthy subjects and in subjects with stable obstructive airway disease. This work includes 2 open-label safety studies. The healthy controls were part of a phase 1 safety study of multiple inhalations of low-dose alkaline glycine buffer; nebulized saline was used as a comparator in 8 of the healthy controls. Subsequently, a phase 2 study in subjects with stable obstructive airway disease was completed using a single nebulized higher-dose strategy of the alkaline inhalation. We studied 20 non-smoking adults (10 healthy controls and 10 subjects with obstructive airway disease), both at baseline and after inhalation of alkaline buffer. We used spirometry and vital signs as markers of clinical safety. We used changes in fraction of exhaled nitric oxide (NO) and exhaled breath condensate (EBC) pH as surrogate markers of airway pH modification. Alkaline glycine inhalation was tolerated by all subjects in both studies, with no adverse effects on spirometric parameters or vital signs. Airway alkalinization was confirmed by a median increase in EBC pH of 0.235 pH units (IQR 0.56-0.03, P = .03) in subjects after inhalation of the higher-dose alkaline buffer (2.5 mL of 100 mmol/L glycine). Alkalinization of airway lining fluid is accomplished with inhalation of alkaline glycine buffer and causes no adverse effects on pulmonary function or vital signs.

Investigation of an alkaline direct ethanol fuel cell with non Pt-catalyst

Energy Technology Data Exchange (ETDEWEB)

Beyer, M.; Guelzow, E.; Uhm, S. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Technische Thermodynamik

2010-07-01

This paper focuses on the characterisation of an alkaline direct ethanol fuel cell (ADEFC). Ethanol and for comparison also methanol was fed to the anode in a caustic potash solution at different concentrations and temperatures. An anion exchange membrane (Tokuyama) sandwiched between two Hypermec electrodes (Acta SpA.) was investigated in a single cell. Current-voltage-measurements (U(I) characteristics), short term operation under load, electrochemical impedance spectroscopy (EIS) and pH recording were carried out to characterize fuel cell performance. The long term objective is to investigate the mechanism of ethanol electro oxidation reaction (EOR). 18 mW/cm{sup 2} was reached at room temperature with a technically oriented 50 cm{sup 2} cell with ethanol. However, poor long term stability under load of the fuel cell is observed. Furthermore in the U(I) characteristics a negative hysteresis is present in the forward and backward scan at room temperature which indicates poisoning intermediates of electrode reactions. A pH decline appears during operation indicating a development of either acetic acid or acetates or acetaldehyde as main products of the ethanol oxidation, which may be responsible for rate decrease of ethanol oxidation with time. EIS measurement shows an increased membrane resistance. (orig.)

Permanganate oxidizable carbon reflects a processed soil fraction that is sensitive to management

Science.gov (United States)

Permanganate oxidizable C (POXC; i.e., active C) is a relatively new method that can quantify labile soil C rapidly and inexpensively. Despite limited reports of positive correlations with particulate organic carbon (POC), microbial biomass carbon (MBC) and other soil carbon (C) fractions, little i...

Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M.P.; Hihn, J.Y., E-mail: jean-yves.hihn@univ-fcomte.fr

2015-11-15

Graphical abstract: Result of an etching step in ultrasound presence on intermetallic particles on a 2024 aluminum alloy. - Highlights: • Etching step prior to anodization on 2024 aluminum alloy. • Etching rate measurement and hydroxide film characterization by GDOES and SEM. • Various etching parameters (temperature, presence or absence of ultrasound). • Improvement of corrosion resistance show by electrochemical tests. - Abstract: Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

International Nuclear Information System (INIS)

Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M.P.; Hihn, J.Y.

2015-01-01

Graphical abstract: Result of an etching step in ultrasound presence on intermetallic particles on a 2024 aluminum alloy. - Highlights: • Etching step prior to anodization on 2024 aluminum alloy. • Etching rate measurement and hydroxide film characterization by GDOES and SEM. • Various etching parameters (temperature, presence or absence of ultrasound). • Improvement of corrosion resistance show by electrochemical tests. - Abstract: Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

Hollow raspberry-like PdAg alloy nanospheres: High electrocatalytic activity for ethanol oxidation in alkaline media

Science.gov (United States)

Peng, Cheng; Hu, Yongli; Liu, Mingrui; Zheng, Yixiong

2015-03-01

Palladium-silver (PdAg) alloy nanospheres with unique structure were prepared using a one-pot procedure based on the galvanic replacement reaction. Their electrocatalytic activity for ethanol oxidation in alkaline media was evaluated. The morphology and crystal structure of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical characterization techniques, including cyclic voltammetry (CV) and chronoamperometry (CA) measurements were used to analyze the electrochemical performance of the PdAg alloy nanospheres. The SEM and TEM images showed that the PdAg alloy nanospheres exhibit a hierarchical nanostructure with hollow interiors and porous walls. Compared to the commercial Pd/C catalyst, the as-prepared PdAg alloy nanospheres exhibit superior electrocatalytic activity and stability towards ethanol electro-oxidation in alkaline media, showing its potential as a new non-Pt electro-catalyst for direct alcohol fuel cells (DAFCs).

Formate detection by potassium permanganate for enhanced hydrogen production in Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Maeda, Toshinari [Artie McFerrin Department of Chemical Engineering, 220 Jack E. Brown Building, Texas A and M University, College Station, TX 77843-3122 (United States); Wood, Thomas K. [Artie McFerrin Department of Chemical Engineering, 220 Jack E. Brown Building, Texas A and M University, College Station, TX 77843-3122 (United States); Department of Biology, Texas A and M University, College Station, TX 77843-3258 (United States); Zachry Department of Civil and Environmental Engineering, Texas A and M University, College Station, TX 77843-3136 (United States)

2008-05-15

Mutagenesis of Escherichia coli for hydrogen production is difficult since there is no high-throughput screen. Here we describe a method for rapid detection of enhanced hydrogen production by engineered strains by detecting formate via potassium permanganate; in E. coli, hydrogen is synthesized from formate using the formate hydrogen lyase system. (author)

Radiolysis of nitrite, bromate and permanganate ions and their binary mixtures in aqueous solutions at pH 10

International Nuclear Information System (INIS)

Dedgaonkar, V.G.; Kulkarni, S.A.; Mahajan, C.T.

1981-01-01

#betta#-radiolysis of pure systems viz. nitrite, bromate and permanganate and their binary mixtures (MNO 4- /NO 2- , MnO 4- /BrO 3- ) in aqueous solution at pH 10 is studied as a function of dose and concentration. In pure systems the G(NO 3- ), G(Br - ) and G(-MnO 4- ) increase with increasing concentration. The first two show an identical limiting value of approximately 0.5 while the last increases from 0.68 below 10 4 M and reaches 2.5 at 10 - 2 M concentration. Presence of 10 - 1 M BrO 3- or 10 - 2 M NO 2- reduces the G(-MnO 4- ) from 1.07 for the pure 10 - 3 M permanganate solution to 0.2 and 0.7 respectively. A mechanism based on the competitive kinetics is envisaged to explain the observed results. (author)

Selective Leaching of Chromium from Hanford Tank Sludge 241-U-108

International Nuclear Information System (INIS)

Rapko, Brian M.; Vienna, John D.

2002-01-01

This study evaluated the oxidants permanganate, MnO4-, and peroxynitrite, ONOO-, as selective chromium-leaching agents from washed 241-U-108 tank sludge under varying conditions of hydroxide concentration, temperature, and time. The mass changes and final sludge compositions were evaluated using glass-property models to ascertain the relative impacts of the various oxidative alkaline leach conditions on the amount of borosilicate glass required to immobilize a given amount of washed 241-U-108 Hanford tank sludge. Only permanganate leaching removes sufficient chromium to make the chromium concentration in the oxidatively alkaline leached solids non-limiting. In the absence of added oxidants, continued washing or caustic leaching have no beneficial effects. Peroxynitrite addition reduces the amount of glass required to immobilize a given amount of washed 241-U-108 tank sludge by approximately a factor of two. Depending on the leach conditions and the exact chromium concentration limits, contact with alkaline permanganate solutions reduces the amount of immobilized high-level waste glass by a factor of 10 to 30

Selective Leaching of Chromium from Hanford Tank Sludge 241-U-108

Energy Technology Data Exchange (ETDEWEB)

Rapko, Brian M.; Vienna, John D.

2002-09-09

This study evaluated the oxidants permanganate, MnO4-, and peroxynitrite, ONOO-, as selective chromium-leaching agents from washed 241-U-108 tank sludge under varying conditions of hydroxide concentration, temperature, and time. The mass changes and final sludge compositions were evaluated using glass-property models to ascertain the relative impacts of the various oxidative alkaline leach conditions on the amount of borosilicate glass required to immobilize a given amount of washed 241-U-108 Hanford tank sludge. Only permanganate leaching removes sufficient chromium to make the chromium concentration in the oxidatively alkaline leached solids non-limiting. In the absence of added oxidants, continued washing or caustic leaching have no beneficial effects. Peroxynitrite addition reduces the amount of glass required to immobilize a given amount of washed 241-U-108 tank sludge by approximately a factor of two. Depending on the leach conditions and the exact chromium concentration limits, contact with alkaline permanganate solutions reduces the amount of immobilized high-level waste glass by a factor of 10 to 30.

Kinetics of the oxidation of cylindrospermopsin and anatoxin-a with chlorine, monochloramine and permanganate.

Science.gov (United States)

Rodríguez, Eva; Sordo, Ana; Metcalf, James S; Acero, Juan L

2007-05-01

Cyanobacteria produce toxins that may contaminate drinking water sources. Among others, the presence of the alkaloid toxins cylindrospermopsin (CYN) and anatoxin-a (ANTX) constitutes a considerable threat to human health due to the acute and chronic toxicity of these compounds. In the present study, not previously reported second-order rate constants for the reactions of CYN and ANTX with chlorine and monochloramine and of CYN with potassium permanganate were determined and the influence of pH and temperature was established for the most reactive cases. It was found that the reactivity of CYN with chlorine presents a maximum at pH 7 (rate constant of 1265 M(-1)s(-1)). However, the oxidation of CYN with chloramine and permanganate are rather slow processes, with rate constants chlorination product of CYN was found to be 5-chloro-CYN (5-Cl-CYN), which reacts with chlorine 10-20 times slower than the parent compound. The reactivity of ANTX with chlorine and chloramines is also very low (kchlorine dose of 1.5 mg l(-1) was enough to oxidize CYN almost completely. However, 3 mg l(-1) of chlorine was able to remove only 8% of ANTX, leading to a total formation of trihalomethanes (TTHM) at a concentration of 150 microg l(-1). Therefore, chlorination is a feasible option for CYN degradation during oxidation and disinfection processes but not for ANTX removal. The permanganate dose required for CYN oxidation is very high and not applicable in waterworks.

Application of electrochemically generated ozone to the discoloration and degradation of solutions containing the dye Reactive Orange 122

International Nuclear Information System (INIS)

Santana, Mario H.P.; Da Silva, Leonardo M.; Freitas, Admildo C.; Boodts, Julien F.C.; Fernandes, Karla C.; De Faria, Luiz A.

2009-01-01

Aqueous solutions containing the commercial azo dye Reactive Orange 122 (RO122) were ozonated in acid and alkaline conditions. Ozone was electrochemically generated using a laboratory-made electrochemical reactor and applied using semi-batch conditions and a column bubble reactor. A constant ozone application rate of 0.25 g h -1 was used throughout. Color removal and degradation efficiency were evaluated as function of ozonation time, pH and initial dye concentration by means of discoloration kinetics and COD-TOC removal. Experimental findings revealed that pH affects both discoloration kinetics and COD-TOC removal. A single pseudo-first-order kinetic rate constant, k obs , for discoloration was found for ozonation carried out in alkaline solutions, contrary to acidic solutions where k obs depends on ozonation time. COD-TOC removal supports degradation of RO122 is more pronounced for alkaline conditions. Evaluation of the oxidation feasibility by means of the COD/TOC ratio indicates that the ozonation process in both acid and alkaline conditions leads to a reduction in recalcitrance of the soluble organic matter

Comparative effects of copper sulfate or potassium permanganate on channel catfish concurrently infected with Flavobacterium columnare and Ichthyobodo necator

Science.gov (United States)

An opportunistic study was conducted to determine the effects of two chemical therapeutants on channel catfish (CCF) Ictalurus punctatus concurrently infected Flavobacterium columnare and Ichthyobodo necator. Copper sulfate (CuSO4) and potassium permanganate (KMnO4) were investigated for their abil...

Outstanding resistance and passivation behaviour of new Fe-Co metal-metal glassy alloys in alkaline media.

Directory of Open Access Journals (Sweden)

Khadijah M Emran

Full Text Available The electrochemical behavior of the oxide layers on two metal-metal glassy alloys, Fe78Co9Cr10Mo2Al1 (VX9and Fe49Co49V2 (VX50 (at.%, were studied using electrochemical techniques including electrochemical frequency modulation (EFM, electrochemical impedance spectroscopy (EIS and cyclic polarization (CP measurements. The morphology and composition of the alloy surfaces were investigated using X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM and atomic force microscopy (AFM. The corrosion rate and surface roughness of both alloys increased as the concentration of NaOH in aqueous solution was raised. The presence of some protective elements in the composition of the alloys led to the formation of a spontaneous passive layer on the alloy surface. The higher resistance values of both alloys were associated with the magnitude of the dielectric properties of the passive films formed on their surfaces. Both alloys are classified as having outstanding resistance to corrosion, which results from the formation of a passive film that acts as an efficient barrier to corrosion in alkaline solution.

Reduction of trihalomethane (THM) formation with potassium permanganate in potable water treatment; Aplicacion del permanganato potasico y la formacion de trihalometanos (THM) en los procesos de potabilizacion del agua

Energy Technology Data Exchange (ETDEWEB)

Aguirre Pascual, G.; Monforte de Monleon, L.; Tos Boix, s.

1996-04-01

Replacing prechlorination with a preoxidation with potassium permanganate in potable water treatment has proved to be an effective way to reduce the formation of THM, organochlorinated compounds known to be carcinogenic. It has been proved that the use of potassium permanganate to reduce the formation of THM is a simple and economic treatment process, having the added affect of improving the taste of the treated water. (Author) 21 refs.

Preparation of anionic clay-birnessite manganese oxide composites by interlayer oxidation of oxalate ions by permanganate

Energy Technology Data Exchange (ETDEWEB)

Arulraj, James [Materials Research Group, Department of Chemistry, St. Joseph' s College, 36 Langford Road, Bangalore 560 027 (India); Rajamathi, Michael, E-mail: mikerajamathi@rediffmail.com [Materials Research Group, Department of Chemistry, St. Joseph' s College, 36 Langford Road, Bangalore 560 027 (India)

2013-02-15

Oxalate intercalated anionic clay-like nickel zinc hydroxysalt was obtained starting from nickel zinc hydroxyacetate, Ni{sub 3}Zn{sub 2}(OH){sub 8}(OAc){sub 2}{center_dot}2H{sub 2}O, by anion exchange. The intercalated oxalate species was reacted with potassium permanganate in such a way that the layered manganese oxide formed was within the interlayer region of the anionic clay resulting in a layered composite in which the negative charges on the birnessite type manganese oxide layers compensate the positive charges on the anionic clay layers. Birnessite to anionic clay ratio could be varied by varying the reaction time or the amount of potassium permanganate used. - Graphical abstract: Nickel zinc hydroxyoxalate was reacted with potassium permanganate to get nickel zinc hydroxide birnessite composites in which the positive charges on the hydroxide layers are neutralized by the negative charges on birnessite layers. Highlights: Black-Right-Pointing-Pointer Anionic and cationic layered solid composites prepared. Black-Right-Pointing-Pointer Ni-Zn hydroxyoxalate reacted with KMnO{sub 4} to deposit MnO{sub 2} in the interlayer. Black-Right-Pointing-Pointer Birnessite layers coexist with anionic clay layers in the composites. Black-Right-Pointing-Pointer Birnessite/anionic clay ratio controlled by amount of KMnO{sub 4} used and reaction time.

A facile approach to prepare crumpled CoTMPyP/electrochemically reduced graphene oxide nanohybrid as an efficient electrocatalyst for hydrogen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Ma, Juanjuan, E-mail: majj0518@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore); Liu, Lin; Chen, Qian; Yang, Min [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Wang, Danping [School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore); Tong, Zhiwei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Chen, Zhong, E-mail: aszchen@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore)

2017-03-31

Highlights: • Crumpled CoTMPyP/ERGO hybrid was successfully prepared by a facile two-step process. • CoTMPyP nanoaggregates are homogeneously distributed over the graphene surface. • CoTMPyP/ERGO hybrid film shows good electrocatalytic activity and stability for HER. - Abstract: Elaborate design and synthesis of efficient and stable non-Pt electrocatalysts for some renewable energy related conversion/storage processes are one of the major goals of sustainable chemistry. Herein, we report a facile method to fabricate Co porphyrin functionalized electrochemically reduced graphene oxide (CoTMPyP/ERGO) thin film by direct assembly of oppositely charged tetrakis(N-methylpyridyl) porphyrinato cobalt (CoTMPyP) and GO nanosheets under mild conditions followed by an electrochemical reduction procedure. STEM analysis confirms that CoTMPyP nanoaggregates are homogeneously distributed over the graphene surface. The electrochemical properties of CoTMPyP/ERGO were investigated by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy. The results demonstrate that CoTMPyP/ERGO nanohybrid film can serve as excellent electrocatalyst for hydrogen evolution in alkaline solution with high activity and stability. The intimate contact and efficient electron transfer between CoTMPyP and ERGO, as well as the crumpled structure, contribute to the improvement of the electrocatalytic performance.

Enhanced permanganate in situ chemical oxidation through MnO2 particle stabilization: evaluation in 1-D transport systems.

Science.gov (United States)

Crimi, Michelle; Quickel, Mark; Ko, Saebom

2009-02-27

In situ chemical oxidation using permanganate is an increasingly employed approach to organic contaminant remediation at hazardous waste sites. Manganese dioxide (MnO2) particles form as a by-product of the reaction of permanganate with contaminants and naturally-reduced subsurface materials. These particles are of interest because they have the potential to deposit in the subsurface and impact the flow regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport, and contact between the oxidant and contaminants of concern. Sodium hexametaphosphate (HMP) has previously been identified as a promising aid to stabilize MnO2 in solution when included in the oxidizing solution, increasing the potential to inhibit particle deposition and impact subsurface flow. The goal of the experimental studies described herein was to investigate the ability of HMP to prevent particle deposition in transport studies using four different types of porous media. Permanganate was delivered to a contaminant source zone (trichloroethylene) located within four different media types with variations in sand, clay, organic carbon, and iron oxides (as goethite) content. Deposition of MnO2 within the columns was quantified with distance from the source zone. Experiments were repeated in replicate columns with the inclusion of HMP directly with the oxidant delivery solution, and MnO2 deposition was again quantified. While total MnO2 deposition within the 60 cm columns did not change significantly with the addition of HMP, deposition within the contaminant source zone decreased by 25-85%, depending on the specific media type. The greatest differences in deposition were observed in the goethite-containing and clay-containing columns. Columns containing these two media types experienced completely plugged flow in the oxidant-only delivery systems; however

A highly reversible anthraquinone-based anolyte for alkaline aqueous redox flow batteries

Science.gov (United States)

Cao, Jianyu; Tao, Meng; Chen, Hongping; Xu, Juan; Chen, Zhidong

2018-05-01

The development of electroactive organic materials for use in aqueous redox flow battery (RFB) electrolytes is highly attractive because of their structural flexibility, low cost and sustainability. Here, we report on a highly reversible anthraquinone-based anolyte (1,8-dihydroxyanthraquinone, 1,8-DHAQ) for alkaline aqueous RFB applications. Electrochemical measurements reveal the substituent position of hydroxyl groups for DHAQ isomers has a significant impact on the redox potential, electrochemical reversibility and water-solubility. 1,8-DHAQ shows the highest redox reversibility and rapidest mass diffusion among five isomeric DHAQs. The alkaline aqueous RFB using 1,8-DHAQ as the anolyte and potassium ferrocyanide as the catholyte yields open-circuit voltage approaching 1.1 V and current efficiency and capacity retention exceeding 99.3% and 99.88% per cycle, respectively. This aqueous RFB produces a maximum power density of 152 mW cm-2 at 100% SOC and 45 °C. Choline hydroxide was used as a hydrotropic agent to enhance the water-solubility of 1,8-DHAQ. 1,8-DHAQ has a maximum solubility of 3 M in 1 M KOH with 4 M choline hydroxide.

In Situ Chemical Oxidation Using Potassium Permanganate. Innovative Technology Summary Report

International Nuclear Information System (INIS)

1999-01-01

The In Situ Chemical Oxidation Using Potassium Permanganate [KMnO4] treats soils or groundwater contaminated with a range of organic chemicals, including trichlorethylene. Potential application to metal and radionuclide contaminants, including oxidation/immobilization of uranium, is being investigated. This technology is designed for use with efficient delivery systems, such as the Multi-Point Injection System and Deep Soil Mixing, to treat contaminants in low permeability soils

Synthesis of CoO/Reduced Graphene Oxide Composite as an Alternative Additive for the Nickel Electrode in Alkaline Secondary Batteries

International Nuclear Information System (INIS)

Fu, Gaoliang; Chang, Kun; Shangguan, Enbo; Tang, Hongwei; Li, Bao; Chang, Zhaorong; Yuan, Xiao-Zi; Wang, Haijiang

2015-01-01

Highlights: • CoO/RGO nanosheets with sandwiched structures were synthesized by hydrothermal method. • CoO/RGO composite can be as a good additive for Ni-MH battery. • Using CoO/RGO as the additive can greatly reduce the utilization of CoO in the commercial battery. • Particularly, the high rate capability of the electrode was enhanced significantly. - Abstract: A series of CoO/reduced graphene oxide (CoO/RGO) composites with different proportions are successfully synthesized via a hydrothermal method. As an additive for the nickel-based alkaline secondary battery cathode, the electrochemical performances of the proposed CoO/RGO composite are systematically investigated on its cyclic stability, rate capability, capacity recovery performance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), in comparison with commercial CoO. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images show that the CoO nanoparticles are in-situ anchored on the surface of soft and flexible graphene sheets. Electrochemical results indicate that the CoO/RGO composites exhibite the highest performance when the weight ratio of CoO and RGO is 5:5. The optimized CoO/RGO composites as an additive for the nickel electrode not only can substantially reduce the CoO additive but also possess good electrochemical performances, especially for the high-rate capability. The discharge capacity of the nickel electrode with 5 wt% of CoO/RGO (5:5) addition deliver a high discharge capacity of 284.3, 264.6,235.4 and 208.6 mAh g"−"1 at 0.2, 1.0, 5.0 and 10.0 C, respectively. The capacity recovery rate at 0.2 C can reach 98.4%. CV and EIS test indicate that the incorporation of RGO can significantly enhance the reversible property, current density of cathodic peak, proton diffusion and conductivity of the nickel electrode.

An electrochemical methanol sensor based on a Pd-Ni/SiNWs catalytic electrode

International Nuclear Information System (INIS)

Tao Bairui; Zhang Jian; Hui Shichao; Chen Xuejiao; Wan Lijuan

2010-01-01

A novel electrochemical methanol sensor based on a catalytic electrode of palladium-nickel/silicon nanowires (Pd-Ni/SiNWs) is presented in this paper. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical methods are employed to investigate the Pd-Ni/SiNWs electrode materials. These nanocomposite materials exhibit a highly ordered, wire-like structure with a wire length of ∼50 μm and a wire diameter ranging from 100 to 300 nm. The substrate has good electrocatalytic activity towards the oxidation of methanol in alkaline solutions. The performances of the prototype sensor are characterized by cyclic voltammetry and fixed potential amperometry techniques. In a 1 mol L -1 KOH solution containing different methanol concentrations, the sensor exhibits a good sensitivity of 1.96 mA mmol -1 L cm -2 with R 2 = 0.99 and the corresponding detection limit of 18 μmol L -1 (signal-to-noise ratio = 3, S/N = 3) for cyclic voltammetry. Meanwhile, the electrode also displays a sensitivity of 0.48 mA mmol -1 L cm -2 with R 2 = 0.98 and the corresponding detection limit of 25 μmol L -1 (S/N = 3) for a fixed potential amperometry at -0.3 V versus an Ag/AgCl reference electrode. The results demonstrate that the Pd-Ni/SiNWs catalytic electrode has potential as an efficient and integrated sensor for methanol detection.

Electrochemical investigations of Co3Fe-RGO as a bifunctional catalyst for oxygen reduction and evolution reactions in alkaline media

Science.gov (United States)

Kumar, Surender; Kumar, Divyaratan; Kishore, Brij; Ranganatha, Sudhakar; Munichandraiah, Nookala; Venkataramanan, Natarajan S.

2017-10-01

Nanoparticles of Co3Fe alloy is prepared on reduced graphene oxide (RGO) sheets by modified polyol method. Synthesized alloy particles are characterized by various physicochemical techniques. TEM and SEM pictures showed homogeneously dispersed alloy nanoparticles on the RGO sheets. Electrochemistry of alloy nanoparticles is investigated in alkaline medium. The result shows that oxygen evaluation reaction (OER) activity of Co3Fe-RGO is higher than Pt-black particles. RDE studies in alkaline medium shows that oxygen reduction reaction (ORR) follow four electron pathway. It is suggest that Co3Fe-RGO is an efficient non-precious catalyst for oxygen (ORR/OER) reactions in alkaline electrolyte for PEMFC applications.

On performance capabilities of alkaline anolyte in wastewater management

International Nuclear Information System (INIS)

Shimkevich, Alexander

2014-01-01

A concept for electric converting a saline wastewater into basic solution (pH > 7) with a positive RedOx potential (alkaline anolyte) is considered. Such the medium can be obtained in situ at flowing wastewater via a special electrochemical cell with strongly polarized cathode (generating hydroxide anions) and quasi-equilibrium anode which intensively discharges hydroxide ions to hydroxyl radicals into the wastewater. The radicals will oxidize anions of strong acid and convert them into weak-acid micro precipitates in the flowing basic solution. These renewable nano-sorbents will uninterruptedly co-precipitate radioactive contamination from wastewater and be agglomerated as corrosion by-products in the felt-like anode. The consideration of liquid water as a chemical compound with a wide band gap shows that the anolyte (as a hyper-stoichiometric water, H 2 O 1+|x| ) is a simple and effective tool for varying physical and chemical properties of the aqueous solution due to forced changing its RedOx potential as one needs. This potential as Fermi level in the band gap of liquid water is the most convenient parameter for monitoring and managing the electrochemical potential of the aqueous medium. Its hyper-stoichiometric state is realized when Fermi level is shifted to the top of a valence band. This electro-oxidized state as the alkaline anolyte is characterized by an acceptor level, OH/OH - , partially occupied by electrons. Then, the hydroxyl radical (OH • ) as the strongest oxidizer will oxidize intensively the metal anode and renew its surface for great removal of radio-nuclides from the wastewater due to their large specific area of renewable surface of hydroxide absorber on the felt-like anode. (author)

Development and characterization of colloidal silica-based slow-release permanganate gel (SRP-G): laboratory investigations.

Science.gov (United States)

Lee, Eung Seok; Gupta, Neha

2014-08-01

Slow-release permanganate (MnO4(-)) gel (SRP-G) is a hyper-saline KMnO4 solution that can be used for treating large, dilute, or deep plumes of chlorinated solvents in groundwater. Ideally, the SRP-G injected into aquifers will slowly gelate to form MnO4(-) gel in situ, and the gel will slowly releases MnO4(-). Objectives of this study were to develop SRP-G using colloidal silica as gelling solution, characterize its gelation and release kinetics, and delineate its dynamics in a saturated sandy media. The SRP-G exhibited a two-phase increase in viscosity: a lag phase characterized by little increase in viscosity followed by a short gelation phase. Gelation lag times of SRP-G solutions increased (from 0.5h to 13d) with decreasing KMnO4 concentrations (from 25 to 8 g L(-1)). Permanganate release from gelated SRP-G increased with increasing KMnO4 concentrations, and was characterized as asymptotic release with initial peak (0.9-2.2 mg min(-1)) followed by more attenuated release. Gelation lag times of SRP-G flowing in sands (linear velocity=2.1md(-1)) increased (1, 3, and 6h) with decreasing KMnO4 concentrations (25.0, 23.0, and 22.9 g L(-1)). Permanganate release from gelated SRP-Gs continued for up to 3d and was characterized as asymptotic release with an initial peak release (∼1.2 g min(-1)) followed by more attenuated release over 70h. Dilution of SRP-G by dispersion in porous media affects gelation and release kinetics. Increasing the silica concentration in the SRP-G may facilitate gelation and extend the duration of MnO4(-) release from emplaced SRP-G in porous media. Copyright © 2014. Published by Elsevier Ltd.

Combined chemical and EIS study of the reaction of zinc coatings under alkaline conditions

International Nuclear Information System (INIS)

Walkner, Sarah; Hassel, Achim Walter

2014-01-01

Graphical abstract: - Highlights: • An electrochemical unit for automatic EIS and pH modulation is used. • ZnMg2Al2 and ZnAl53 are studied in alkaline solutions. • Amount of consumed sodium hydroxide allows following hydroxide formation and film thickness. • Cross sections of 13 μm show excellent agreement with consumed hydroxide. • ZnAl53 consumes more hydroxide due to soluble aluminate formation. - Abstract: Two different zinc coatings of composition ZnMg2Al2 (Zn + 2 wt.% Mg + 2 wt.% Al) and ZnAl53 (Zn + 53 wt.% Al) were investigated in aqueous solution at pH 12.0 with a novel setup, the so-called impedance titrator. This device is able to perform electrochemical measurements including, but not limited to, impedance spectroscopy in dependency of different pH-values. The setup allows holding the pH-value with a precision of at least 0.05 by dosing the required amount of titrating agent to the system. If the alkaline pH region is investigated, hydroxide ions are consumed in the course of passive layer formation. The amount of consumed hydroxide allows to quantitatively follow the formation of the hydroxide film and its thickness. Cross section SEM shows an excellent agreement of 13 μm after 7 h for ZnMg2Al2. At a constant pH value, the hydroxide concentration is constant and film formation is well defined and kinetically characterised. The consumption of hydroxide by the ZnAl53 coating is higher resulting from the solubility of the Al as aluminate under alkaline conditions. The composition of the precipitates contains less than 3 wt.% of Al. The observed processes and the formation of corrosion products are recorded and differences in the behaviour of the two coatings are discussed

Oxidizing purification of liquid radioactive waste from organic substances and radionuclides by K permanganate

International Nuclear Information System (INIS)

Rudenko, L.I.; Dzhuzha, O.V.; Khan, V.E.

2007-01-01

The basic opportunity of the oxidizing purification of liquid radioactive waste (LRW) with the use of a water solution of potassium permanganate for the preliminary preparation of LRW at a stage prior to the evaporating devices of the Chernobyl NPP is shown

Investigation of aluminum gate CMP in a novel alkaline solution

International Nuclear Information System (INIS)

Feng Cuiyue; Liu Yuling; Sun Ming; Zhang Wenqian; Zhang Jin; Wang Shuai

2016-01-01

Beyond 45 nm, due to the superior CMP performance requirements with the metal gate of aluminum in the advanced CMOS process, a novel alkaline slurry for an aluminum gate CMP with poly-amine alkali slurry is investigated. The aluminum gate CMP under alkaline conditions has two steps: stock polishing and fine polishing. A controllable removal rate, the uniformity of aluminum gate and low corrosion are the key challenges for the alkaline polishing slurry of the aluminum gate CMP. This work utilizes the complexation-soluble function of FA/O II and the preference adsorption mechanism of FA/O I nonionic surfactant to improve the uniformity of the surface chemistry function with the electrochemical corrosion research, such as OCP-TIME curves, Tafel curves and AC impedance. The result is that the stock polishing slurry (with SiO 2 abrasive) contains 1 wt.% H 2 O 2 ,0.5 wt.% FA/O II and 1.0 wt.% FA/O I nonionic surfactant. For a fine polishing process, 1.5 wt.% H 2 O 2 , 0.4 wt.% FA/O II and 2.0 wt.% FA/O I nonionic surfactant are added. The polishing experiments show that the removal rates are 3000 ± 50 Å/min and 1600 ± 60 Å/min, respectively. The surface roughnesses are 2.05 ± 0.128 nm and 1.59 ± 0.081 nm, respectively. A combination of the functions of FA/O II and FA/O I nonionic surfactant obtains a controllable removal rate and a better surface roughness in alkaline solution. (paper)

Effect of γ radiation on the solution of potassium permanganate complex with di-tert.-butyl-dibenzo-18-crown-6 in benzene

International Nuclear Information System (INIS)

Makhlyarchuk, V.V.; Zatonskij, S.V.; Mikhajlenko, I.E.; Saraeva, V.V.

1987-01-01

Effect of 60 Co gamma-radiation on benzene containing KMnO 4 solubilized with crown-ether is studied. Radiation was carried out at room temperature with doses up to 28 kGy at dose rate of 3.9 Gy/s. Sharp increase of diphenyl yield and absence of phenylcyclohexadiene (PCH) in radiolysis products points out interaction of permanganate-ion with predecessors of PCH formation. High yield of permanganate decomposition results from reactions with excited molecules of the solvent

Effectiveness of copper sulfate and potassium permanganate on channel catfish infected with Flavobacterium columnare

Science.gov (United States)

Copper sulfate (CuSO4) and potassium permanganate (KMnO4) were evaluated for their effectiveness to curtail mortality and decrease bacterial load in fish tissues and water in channel catfish Ictalurus punctatus naturally infected with Flavobacterium columnare, the causative agent of columnaris. Fis...

Hot atom chemistry in oxyanion targets: Part 3. Some theoretical aspects of reincorporation of parent form in permanganates

International Nuclear Information System (INIS)

Mishra, S.P.; Singh, J.

1988-01-01

An attempt is made to advance qualitative and quantitative interpretations for the observed data on retention of recoil 56 Mn in potassium and ammonium permanganates in the light of following physical models; (a) extreme back-diffusion model, (b) billiard-ball collision model and (c) hot zone model. (author). 6 tables, 22 refs

Potassium permanganate and tetraethylammonium chloride are a safe and effective substitute for osmium tetroxide in solid-phase fluorescent chemical cleavage of mismatch.

OpenAIRE

Roberts, E; Deeble, V J; Woods, C G; Taylor, G R

1997-01-01

Whilst chemical cleavage of mismatch (CCM) detects all point mutations in DNA, its widespread use has been hampered by the complex multistage methodology and the need for toxic chemicals, in particular osmium tetroxide. Here we show that osmium tetroxide can be replaced by potassium permanganate, giving the same spectrum of mutation detection, but with greater sensitivity. The use of potassium permanganate is compatible with solid phase capture and fluorescent detection, giving a safer method...

Intricate Estimation and Assessment of Surface Conditioning of Posts to improve Interfacial Adhesion in Post-core Restorations: An in vitro Study.

Science.gov (United States)

Gupta, Priyanka; Sharma, Amil; Pathak, Vivek K; Mankeliya, Saurabh; Bhardwaj, Shivanshu; Dhanare, Poorvasha

2017-12-01

Post and core restorations are routinely used for restoring grossly decayed tooth structures. Various chemical agents are known to affect the interfacial adhesions between the post and the core. Hence, we planned the present study to evaluate the effect of various post-surface treatments on the interfacial strength between the posts and composite materials that are used for building up the core portion. The present study included assessment of the effect of surface conditioning of posts on the interfacial adhesion in post-core restorations. A total of 80 clear post-tapers were included and were divided broadly into four study groups based on the type of chemical testing protocols used. Various chemical treatments included alkaline potassium permanganate, hydrogen peroxide, and phosphoric acid. The fourth group was the control group. The composite core material was used for building up the core. Testing of the tensile load was done on a universal testing machine. All the results were analyzed by the Statistical Package for the Social Sciences (SPSS) software. The highest bond strength was observed in the study group treated with alkaline potassium permanganate, while the lowest was observed in the control group followed by the hydrogen peroxide group. While comparing the mean bond strength in between various study groups, significant results were obtained. Chemical treatment protocol significantly alters the mean bond strength of the post and core restoration. Potassium permanganate significantly increases the bond strength between the fiber post and core restoration.

XPERT DESIGN AND DIAGNOSTICS' (XDD) IN-SITU CHEMICAL OXIDATION PROCESS USING POTASSIUM PERMANGANATE (KMNO4)

Science.gov (United States)

Xpert Design and Diagnostic's (XDD)potassium permanganate in situ chemical oxidation (ISCO) process was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program at the former MEC Building site located in Hudson, New Hampshire. At this site, both soil and ...

Antioxidant capacity of cornelian cherry (Cornus mas L.) - comparison between permanganate reducing antioxidant capacity and other antioxidant methods.

Science.gov (United States)

Popović, Boris M; Stajner, Dubravka; Slavko, Kevrešan; Sandra, Bijelić

2012-09-15

Ethanol extracts (80% in water) of 10 cornelian cherry (Cornus mas L.) genotypes were studied for antioxidant properties, using methods including DPPH(), ()NO, O(2)(-) and ()OH antiradical powers, FRAP, total phenolic and anthocyanin content (TPC and ACC) and also one relatively new, permanganate method (permanganate reducing antioxidant capacity-PRAC). Lipid peroxidation (LP) was also determined as an indicator of oxidative stress. The data from different procedures were compared and analysed by multivariate techniques (correlation matrix calculation and principal component analysis (PCA)). Significant positive correlations were obtained between TPC, ACC and DPPH(), ()NO, O(2)(-), and ()OH antiradical powers, and also between PRAC and TPC, ACC and FRAP. PCA found two major clusters of cornelian cherry, based on antiradical power, FRAP and PRAC and also on chemical composition. Chemometric evaluation showed close interdependence between PRAC method and FRAP and ACC. There was a huge variation between C. mas genotypes in terms of antioxidant activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

The effect of conditioning by permanganate on the dissolution behavior of stellite particles in organic complexing acid medium

International Nuclear Information System (INIS)

Subramanian, V.; Chandramohan, P.; Srinivasan, M.P.; Sukumar, A.A.; Raju, V.S.; Velmurugan, S.; Narasimhan, S.V.

2004-01-01

Radioactive hotspots found either in the primary heat transport circuit or auxiliary circuits of nuclear reactors are mainly due to particles containing activated cobalt. The main source of these particles are stellite alloys that are rich in cobalt and are used in primary cooling circuits in valves, pumps, etc. Due to either mechanical erosion or erosion coupled with corrosion under flow conditions (known as tribocorrosion), these stellite particles are released into the system. They are then activated by neutron absorption in the reactor core before being deposited on out-of-core surfaces, causing radiation exposure problems. In this paper, the possibility of dissolving stellite particles by using an oxidation-complexation process has been explored. Permanganate based reagents were evaluated for their efficiency in conditioning the stellite particles for their dissolution with organic acids. Permanganic acid was found to be the superior conditioning agent. Two alloys of stellite, viz. stellites no. 3 and no. 6, were studied with respect to their dissolution behavior

Preparation and performance evaluation of novel alkaline stable anion exchange membranes

Science.gov (United States)

Irfan, Muhammad; Bakangura, Erigene; Afsar, Noor Ul; Hossain, Md. Masem; Ran, Jin; Xu, Tongwen

2017-07-01

Novel alkaline stable anion exchange membranes are prepared from various amounts of N-methyl dipicolylamine (MDPA) and brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). The dipicolylamine and MDPA are synthesized through condensation reaction and confirmed by 1H NMR spectroscopy. The morphologies of prepared membranes are investigated by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy and scanning electron microscopy (SEM). The electrochemical and physical properties of AEMs are tested comprising water uptake (WU), ion exchange capacity (IEC), alkaline stability, linear expansion ratio (LER), thermal stability and mechanical stability. The obtained hydroxide conductivity of MDPA-4 is 66.5 mS/cm at 80 °C. The MDPA-4 membrane shows good alkaline stability, high hydroxide conductivity, low methanol permeability (3.43 × 10-7 cm2/s), higher selectivity (8.26 × 107 mS s/cm3), less water uptake (41.1%) and lower linear expansion (11.1%) despite of high IEC value (1.62 mmol/g). The results prove that MDPA membranes have great potential application in anion exchange membrane fuel cell.

Research factors of the electrochemical remediation clay soils from the nitrates

Energy Technology Data Exchange (ETDEWEB)

Korolev, V.A.; Babakina, O.A. [Moscow State Univ. (Russian Federation)

2001-07-01

The electrokinetic's methods are prevalent [1, 2], but abilities of the method for remediation nitrates contaminated soils are studied insufficiently. The investigations of effectiveness electrochemical remediation are complicated by processes of reduction nitrates to nitrites (that are more toxic) and then to nitrogen in soil under the constant electric current. Therefore, the objectives of the research was following: - Evaluate mechanism of electrokinetic's removing nitrates from soil; - Evaluate basic value of moisture and alkalinity influence for electrochemical remediation of soil from nitrates; - Determine flow-through regime effect on electrokinetic's treating. (orig.)

Continuous electrochemical oxidation of biomass derived 5-(hydroxymethyl)furfural into 2,5-furandicarboxylic acid

NARCIS (Netherlands)

Latsuzbaia, R.; Bisselink, R.; Anastasopol, A.; Meer, van der H.; Heck, van R.; Yagüe, M.S.; Zijlstra, M.; Roelands, M.; Crockatt, M.; Goetheer, E.; Giling, E.

2018-01-01

Abstract: A continuous electrochemical process with integrated product separation has been developed for production of 2,5-furandicarboxylic acid (FDCA) by oxidation of 5-(hydroxymethyl)furfural (HMF) in aqueous alkaline media on non-noble Ni/NiOOH foam electrodes at ambient conditions. Initially,

Novel application of vacuum sealing drainage with continuous irrigation of potassium permanganate for managing infective wounds of gas gangrene.

Science.gov (United States)

Hu, Ning; Wu, Xing-Huo; Liu, Rong; Yang, Shu-Hua; Huang, Wei; Jiang, Dian-Ming; Wu, Qiang; Xia, Tian; Shao, Zeng-Wu; Ye, Zhe-Wei

2015-08-01

Traumatic gas gangrene is a fatal infection mainly caused by Clostridium perfringens. It is a challenge to manage gas gangrene in open wounds and control infection after debridement or amputation. The aim of the present study was to use vacuum sealing drainage (VSD) with continuous irrigation of potassium permanganate to manage infective wounds of gas gangrene and observe its clinical efficacy. A total of 48 patients with open traumatic gas gangrene infection were included in this study. Amputations were done for 27 patients, and limb salvage procedures were performed for the others. After amputation or aggressive debridement, the VSD system, including polyvinyl alcohol (PVA) foam dressing and polyurethane (PU) film, with continuous irrigation of 1:5000 potassium permanganate solutions, was applied to the wounds. During the follow-up, all the patients healed without recurrence within 8-18 months. There were four complications. Cardiac arrest during amputation surgery occurred in one patient who suffered from severe septic shock. Emergent resuscitation was performed and the patient returned to stable condition. One patient suffered from mixed infection of Staphylococcal aureus, and a second-stage debridement was performed. One patient suffered from severe pain of the limb after the debridement. Exploratory operation was done and the possible reason was trauma of a local peripheral nerve. Three cases of crush syndrome had dialysis treatment for concomitant renal failure. In conclusion, VSD can convert open wound to closed wound, and evacuate necrotic tissues. Furthermore, potassium permanganate solutions help eliminate anaerobic microenvironment and achieve good therapeutic effect on gas gangrene and mixed infection. VSD with continuous irrigation of potassium permanganate is a novel, simple and feasible alternative for severe traumatic open wounds with gas gangrene infection.

Modification of cyanobacterial bloom-derived biomass using potassium permanganate enhanced the removal of microcystins and adsorption capacity toward cadmium (II)

International Nuclear Information System (INIS)

Shao, Jihai; Gu, Ji-Dong; Peng, Liang; Luo, Si; Luo, Huili; Yan, Zhiyong; Wu, Genyi

2014-01-01

Highlights: • Potassium permanganate removed microcystins in the cyanobacterial bloom-derived biomass (CBDB). • Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB. • Manganese dioxide was formed on the surface of CBDB. • Potassium permanganate oxidation process increased the adsorption capacity of CBDB toward Cd(II). - Abstract: Cyanobacterial biomass shows high adsorption capacity toward heavy metal ions. However, the cyanotoxins in the cyanobacterial biomass inhibit its application in heavy metals removal. In order to safely and effectively remove Cd(II) from water using cyanobacterial bloom-derived biomass (CBDB), KMnO 4 was used to modify CBDB. The results indicated that the microcystins in the CBDB were successfully removed by KMnO 4 . Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB, and formed manganese dioxide on the surface of CBDB. The oxidized CBDB showed higher adsorption capacity toward Cd(II) than that of unoxidized treatment. The optimal KMnO 4 concentration for increasing the adsorption capacity of CBDB toward Cd(II) was 0.2 g/L. The adsorption isotherm of Cd(II) by oxidized- or unoxidized-CBDB was well fitted by Langmuir model, indicating that the adsorption of Cd(II) by CBDB was monolayer adsorption. The desorption ratio of Cd(II) from oxidized CBDB was higher than that from unoxidized CBDB in the desorption process using NH 4 NO 3 and EDTA as desorbent. The results presented in this study suggest that KMnO 4 modified CBDB may be used as a safe and high efficient adsorbent in Cd(II) removal from water

Spectrophotometric methods for the determination of ampicillin by potassium permanganate and 1-chloro-2,4-dinitrobenzene in pharmaceutical preparations

Directory of Open Access Journals (Sweden)

Aftab Aslam Parwaz Khan

2015-03-01

Full Text Available Two simple and sensitive kinetic methods for the determination of ampicillin (AMP are described. The first method is based on kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 25 min. The absorbance of the colored manganate ions is measured at 610 nm. The second method is based on the reaction of AMP with 1-chloro-2,4-dinitrobenzene (CDNB in the presence of 0.1 mol L−1 sodium bicarbonate. Spectrophotometric measurement was achieved by recording the absorbance at 490 nm for a fixed time of 60 min. All variables affecting the development of the color were investigated and the conditions were optimized. Plots of absorbance against concentration in both procedures were rectilinear over the ranges 5–30 and 50–260 μg mL−1, with mean recoveries 99.80 and 99.91, respectively. The proposed methods were successfully applied for the determination of AMP in bulk powder and in capsule dosage form. The determination of AMP by the fixed concentration method is feasible with the calibration equations obtained, but the fixed time method proves to be more applicable.

Highly sensitive electrochemical detection of methyl salicylate using electroactive gold nanoparticles.

Science.gov (United States)

Umasankar, Yogeswaran; Ramasamy, Ramaraja P

2013-11-07

Electrochemical sensing of methyl salicylate, a key plant volatile has been achieved using a gold nanoparticle (AuNP) modified screen printed carbon electrode (SPCE). The electrochemical response of planar gold electrodes, SPCE and AuNP-SPCE in alkaline electrolyte in the presence and absence of methyl salicylate were studied to understand the amperometric response of various electrochemical reactions. The reaction mechanism includes hydrolysis of methyl salicylate and the oxidation of negative species. The electrochemical responses were recorded using cyclic voltammetry and differential pulse voltammetry techniques, where the results showed characteristic signals for methyl salicylate oxidation. Among the examined electrodes, AuNP-SPCE possessed three fold better sensitivity than planar gold and 35 times better sensitivity than SPCE (at 0.5 V). The methyl salicylate sensing by AuNP-SPCE possessed 95% of its methyl salicylate response. The electroanalytical results of soybean extract showed that AuNP-SPCE can be employed for the determination of methyl salicylate in real samples.

A survey of decontamination processes applicable to DOE nuclear facilities

International Nuclear Information System (INIS)

Chen, L.; Chamberlain, D.B.; Conner, C.; Vandegrift, G.F.

1997-05-01

The objective of this survey was to select an appropriate technology for in situ decontamination of equipment interiors as part of the decommissioning of U.S. Department of Energy nuclear facilities. This selection depends on knowledge of existing chemical decontamination methods. This report provides an up-to-date review of chemical decontamination methods. According to available information, aqueous systems are probably the most universally used method for decontaminating and cleaning metal surfaces. We have subdivided the technologies, on the basis of the types of chemical solvents, into acid, alkaline permanganate, highly oxidizing, peroxide, and miscellaneous systems. Two miscellaneous chemical decontamination methods (electrochemical processes and foam and gel systems) are also described. A concise technical description of various processes is given, and the report also outlines technical considerations in the choice of technologies, including decontamination effectiveness, waste handing, fields of application, and the advantages and limitations in application. On the basis of this survey, six processes were identified for further evaluation. 144 refs., 2 tabs

A survey of decontamination processes applicable to DOE nuclear facilities

Energy Technology Data Exchange (ETDEWEB)

Chen, L.; Chamberlain, D.B.; Conner, C.; Vandegrift, G.F.

1997-05-01

The objective of this survey was to select an appropriate technology for in situ decontamination of equipment interiors as part of the decommissioning of U.S. Department of Energy nuclear facilities. This selection depends on knowledge of existing chemical decontamination methods. This report provides an up-to-date review of chemical decontamination methods. According to available information, aqueous systems are probably the most universally used method for decontaminating and cleaning metal surfaces. We have subdivided the technologies, on the basis of the types of chemical solvents, into acid, alkaline permanganate, highly oxidizing, peroxide, and miscellaneous systems. Two miscellaneous chemical decontamination methods (electrochemical processes and foam and gel systems) are also described. A concise technical description of various processes is given, and the report also outlines technical considerations in the choice of technologies, including decontamination effectiveness, waste handing, fields of application, and the advantages and limitations in application. On the basis of this survey, six processes were identified for further evaluation. 144 refs., 2 tabs.

Crystal size effect on the electrochemical oxidation of formate on carbon-supported palladium nanoparticles

International Nuclear Information System (INIS)

Santos, Rayana Marcela Izidoro da Silva; Nakazato, Roberto Zenhei; Ciapina, Eduardo Goncalves

2016-01-01

Full text: The electrochemical oxidation of formate in alkaline electrolytes has emerged an a promising anodic reaction in the Direct Formate Fuel Cells[1]. Although palladium is considered to be one of the best electro catalyst for the oxidation of formate, important structure-activity relationships are still not understood. In the present work, we investigated the effect of the size of the palladium crystals in the electrochemical oxidation of formate in 0.1 mol L -1 KOH. Carbon-supported palladium nanoparticles (Pd/C) were prepared by chemical reduction of palladium (II) chloride in aqueous media by sodium borohydride in the presence of varying quantities of sodium citrate in the reaction media to obtain metallic crystals with distinct sizes. Analysis of the X-ray diffraction profile revealed the presence of palladium crystals in the range of 6 to 19 nm. Potentiostatic oxidation of formate on the distinct Pd/C samples revealed a volcano-like dependence of the specific activity with the size of the palladium crystals, presenting the highest activity for crystals around 7.5 nm. Reference: [1] A.M. Bartrom, J.L. Haan, The direct formate fuel cell with an alkaline anion exchange membrane, J. Power Sources. 214 (2012) 68-74. (author)

Carbon quantum dots directly generated from electrochemical oxidation of graphite electrodes in alkaline alcohols and the applications for specific ferric ion detection and cell imaging.

Science.gov (United States)

Liu, Mengli; Xu, Yuanhong; Niu, Fushuang; Gooding, J Justin; Liu, Jingquan

2016-04-25

Carbon quantum dots (CQDs) are attracting tremendous interest owing to their low toxicity, water dispersibility, biocompatibility, optical properties and wide applicability. Herein, CQDs with an average diameter of (4.0 ± 0.2) nm and high crystallinity were produced simply from the electrochemical oxidation of a graphite electrode in alkaline alcohols. The as-formed CQDs dispersion was colourless but the dispersion gradually changed to bright yellow when stored in ambient conditions. Based on UV-Vis absorption, fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM), this colour change appeared to be due to oxygenation of surface species over time. Furthermore, the CQDs were used in specific and sensitive detection of ferric ion (Fe(3+)) with broad linear ranges of 10-200 μM with a low limit of detection of 1.8 μM (S/N = 3). The application of the CQDs for Fe(3+) detection in tap water was demonstrated and the possible mechanism was also discussed. Finally, based on their good characteristics of low cytotoxicity and excellent biocompatibility, the CQDs were successfully applied to cell imaging.

Hydrogen production by alkaline water electrolysis

Directory of Open Access Journals (Sweden)

Diogo M. F. Santos

2013-01-01

Full Text Available Water electrolysis is one of the simplest methods used for hydrogen production. It has the advantage of being able to produce hydrogen using only renewable energy. To expand the use of water electrolysis, it is mandatory to reduce energy consumption, cost, and maintenance of current electrolyzers, and, on the other hand, to increase their efficiency, durability, and safety. In this study, modern technologies for hydrogen production by water electrolysis have been investigated. In this article, the electrochemical fundamentals of alkaline water electrolysis are explained and the main process constraints (e.g., electrical, reaction, and transport are analyzed. The historical background of water electrolysis is described, different technologies are compared, and main research needs for the development of water electrolysis technologies are discussed.

The electrochemical property of the electrodeposited magnetite electrode with different pH values

International Nuclear Information System (INIS)

Kim, Myong-Jin; Kim, Dong Jin; Kim, Hong Pyo

2014-01-01

Flow accelerated corrosion (FAC) is influenced by many factors such as the water chemistry (temperature, pH, dissolved oxygen (D.O.) in a solution, and etc.), chemical composition of carbon steel, and fluid dynamics. Magnetite is formed at the inner surface of carbon steel, and protects the integrity of pipes from damage. The magnetite has a stable state at each equilibrium condition, so that it can be dissolved into the fluid under conditions that satisfy the equilibrium state. The iron solubility can be calculated by considering the reaction equilibrium constants for prediction of the change in the magnetite layer. On the other hand, it is necessary to measure the experimental solubility to compare the theoretical data and the experimental data. In addition, the solubility of magnetite can be predicted by measuring the electrochemical experiments. However, there are few studies related to the electrochemical property of magnetite owing to the difficulty of the electrode fabrication. In the present work, a magnetite electrode was prepared using the electrochemical-assisted precipitation method, and the electrochemical property of the fabricated magnetite electrode was measured in an alkaline solution. The magnetite electrode was fabricated by using the electrochemical-assisted precipitation method for the measurement of the solubility of the magnetite. The prepared magnetite electrode showed the characteristic of the magnetite by an XRD spectrum

pH in atomic scale simulations of electrochemical interfaces

DEFF Research Database (Denmark)

Rossmeisl, Jan; Chan, Karen; Ahmed, Rizwan

2013-01-01

Electrochemical reaction rates can strongly depend on pH, and there is increasing interest in electrocatalysis in alkaline solution. To date, no method has been devised to address pH in atomic scale simulations. We present a simple method to determine the atomic structure of the metal......|solution interface at a given pH and electrode potential. Using Pt(111)|water as an example, we show the effect of pH on the interfacial structure, and discuss its impact on reaction energies and barriers. This method paves the way for ab initio studies of pH effects on the structure and electrocatalytic activity...

Non-Enzymatic Wearable Sensor for Electrochemical Analysis of Perspiration Glucose.

Science.gov (United States)

Zhu, Xiaofei; Ju, Yinhui; Chen, Jian; Liu, Deye; Liu, Hong

2018-05-16

We report a non-enzymatic wearable sensor for electrochemical analysis of perspiration glucose. Multi-potential steps are applied on a Au electrode, including a high negative pretreatment potential step for proton reduction which produc-es a localized alkaline condition, a moderate potential step for electrocatalytic oxidation of glucose under the alkaline condi-tion, and a positive potential step to clean and reactivate the electrode surface for the next detection. Fluorocarbon-based materials were coated on the Au electrode for improving the selectivity and robustness of the sensor. A fully integrated wrist-band is developed for continuous real-time monitoring of perspiration glucose during physical activities, and uploading the test result to a Smartphone App via Bluetooth.

Radiolysis of permanganate and its mixtures with bromate and nitrate ions in solution at pH 10

International Nuclear Information System (INIS)

Dedgaonkar, V.G.; Kulkarni, S.A.; Mahajan, C.T.

1981-01-01

γ-radiolysis of aqueous solutions of pure permanganate and its binary mixture with nitrite and bromate ions at pH 10 is studied as a function of concentration and dose. In pure system G(-MnO 4 - ) increases with the increase in initial concentration from 0.68 to a maximum of 25. The rise is sharp above 10 -2 M concentration which indicates the occurrence of a chain mechanism. In the presence of bromate or nitrite the G value decreases: the G(-MnO 4 - ) in 10 -3 M permanganate solution is 1.07, with 10 -1 M bromate it is 0.2 and with 10 -2 M nitrite it is 0.7. A mechanism based on the cometitive kinetics is envisaged to explain the observed results. (author)

The chemical and electrochemical anisotropic etching of silicon

International Nuclear Information System (INIS)

Dixon, E.

1997-06-01

The success of silicon IC technology in producing a wide variety of microstructures relies heavily on the orientation dependant etching observed for silicon in alkaline media. Despite the rapid growth of this industry, the chemical and electrochemical mechanisms by which anisotropic etching occurs remain poorly understood. The most common etchant systems in use are ethylenediamine-pyrocatechol-water (EPW) and potassium hydroxide-isopropanol-water (KOH-IPA), and whilst these systems are highly plane selective they each have distinct disadvantages. The occurrence of inhomogeneities such as micropyramids and pits on the surface of etched substrates is a particularly disadvantageous characteristic of many alkaline etching systems. A complete understanding of the chemical and electrochemical anisotropic etching mechanisms is essential in order to obtain more reproducible etching, improved etch rate ratios and the development of more reliable etching baths. Wet chemical etching experiments to evaluate the etching rates for the different alkali metal cations have shown that similar etch rates are observed for LiOH, NaOH and KOH but those of RbOH and CsOH are significantly lower. The presence of impurities was shown to worsen the etched wafer's surface finish obtained in these etching baths. Additives have been shown to dramatically improve the surface finish with the presence of IPA in conjunction with etchant oxygenation virtually eliminating all surface defects. Electrochemical experiments were used to assess the electrochemical behaviour of Si p-(100) in of a wide variety of etchants and variations were seen according to the etchant used. A.C impedance spectroscopy showed a variation in the flat-band potential (V FB ) according to alkali metal hydroxide etchant used. These trends were similarly observed in the presence of isopropanol. Oxygenation was observed to reproducibly alter the flat-band potentials. A.c impedance spectroscopic studies additionally confirmed the

Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium; Preparacao e caracterizacao de eletrocatalisadores a base de paladio para oxidacao eletroquimica de alcoois em meio alcalino

Energy Technology Data Exchange (ETDEWEB)

Brandalise, Michele

2012-07-01

In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

Oxidative removal of quinclorac by permanganate through a rate-limiting [3 + 2] cycloaddition reaction.

Science.gov (United States)

Song, Dean; Cheng, Hanyang; Jiang, Xiaohua; Sun, Huiqing; Kong, Fanyu; Liang, Rongning; Qiang, Zhimin; Liu, Huijuan; Qu, Jiuhui

2018-04-05

Quinclorac, a widely used herbicide in agriculture, has been recognized as an emerging environmental pollutant owing to its long persistence and potential risk to humans. However, no related information is available on the degradation of quinclorac by employing oxidants. Herein, the reactivity of quinclorac with permanganate was systematically investigated in water by combining experimental and computational approaches. The reaction followed overall second-order kinetics pointing to a bimolecular rate-limiting step. The second-order rate constant was found to be 3.47 × 10-3 M-1 s-1 at 25 °C, which was independent of pH over the range from 5 to 9 and was dependent on temperature over the range from 19 to 35 °C. The initial product was identified by UPLC-Q-TOF-MS to be mono-hydroxylated quinclorac, which was more susceptible to further oxidation. The result could be supported by the complete simulation of the reaction process in DFT calculations, indicating the [3 + 2] cycloaddition oxidation of the benzene ring in the rate-limiting step. The plausible mechanism was then proposed, accompanied by the analysis of the HOMO indicating the hydroxylation position and of the ESP suggesting a more electron-rich moiety. Considering the high effectiveness and low toxicity, permanganate oxidation was considered to be a very promising technique for removing quinclorac from aquatic environments.

Oxidation of alkylarenes to the corresponding acids using aqueous potassium permanganate by hydrodynamic cavitation.

Science.gov (United States)

Ambulgekar, G V; Samant, S D; Pandit, A B

2004-05-01

Oxidation of toluene using aqueous potassium permanganate was studied under heterogeneous condition in the presence of hydrodynamic cavitation and compared with the results of the reaction under acoustic cavitation. Various parameters, such as quantity of potassium permanganate, toluene to aqueous phase ratio, reaction time and cavitation parameters such as orifice plate, and pump discharge pressure were optimized. The reaction was found to be considerably accelerated at ambient temperature in the presence of cavitation. On comparison, it was found that when 1 kJ of energy was passed to the reaction mixture in the case of acoustic cavitation, the product obtained was 4.63 x 10(-6) mol, whereas when 1 kJ of energy was passed to the reaction mixture in the case of hydrodynamic cavitation the product obtained was 2.70 x 10(-5) mol. Hence, about six times more product would be obtained in the case of hydrodynamic cavitation than in the case of acoustic cavitation at same energy dissipation. It has been observed that further optimization is possible.

Method of cleaning alkaline metal

International Nuclear Information System (INIS)

Kawakami, Yukio; Naito, Kesahiro; Iizawa, Katsuyuki; Nakasuji, Takashi

1981-01-01

Purpose: To prevent scattering of used sodium and aqueous alkaline solution when cleaning used sodium and metallic sodium adhering to equipment with an aqueous alkaline solution. Method: A sodium treating container is filled with an aqueous alkaline solution, and stainless steel gauze is sunk in the container. Equipment to be cleaned such as equipment with sodium adhering to it are retained under the gauze and are thus cleaned. On the other hand, the surface of the aqueous alkaline solution is covered with a fluid paraffin liquid covering material. Thus, the hydrogen produced by the reaction of the sodium and the aqueous alkaline solution will float up, pass through the liquid covering material and be discharged. The sodium will pass through the gauze and float upwardly while reacting with the aqueous alkaline solution in a partic ulate state to the boundary between the aqueous alkaline solution and up to the covering material, and thus the theratment reaction will continue. Thus, the cover material prevents the sodium and the aqueous alkaline solution from scattering. (Kamimura, M.)

Electrochemical hydrogen Storage Systems

International Nuclear Information System (INIS)

Macdonald, Digby

2010-01-01

As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the

Electrochemical hydrogen Storage Systems

Energy Technology Data Exchange (ETDEWEB)

Dr. Digby Macdonald

2010-08-09

As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

Modification of cyanobacterial bloom-derived biomass using potassium permanganate enhanced the removal of microcystins and adsorption capacity toward cadmium (II)

Energy Technology Data Exchange (ETDEWEB)

Shao, Jihai [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha 410128 (China); Gu, Ji-Dong [Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha 410128 (China); Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Peng, Liang; Luo, Si; Luo, Huili [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Yan, Zhiyong, E-mail: zhyyan111@163.com [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Wu, Genyi, E-mail: wugenyi99@163.com [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China)

2014-05-01

Highlights: • Potassium permanganate removed microcystins in the cyanobacterial bloom-derived biomass (CBDB). • Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB. • Manganese dioxide was formed on the surface of CBDB. • Potassium permanganate oxidation process increased the adsorption capacity of CBDB toward Cd(II). - Abstract: Cyanobacterial biomass shows high adsorption capacity toward heavy metal ions. However, the cyanotoxins in the cyanobacterial biomass inhibit its application in heavy metals removal. In order to safely and effectively remove Cd(II) from water using cyanobacterial bloom-derived biomass (CBDB), KMnO{sub 4} was used to modify CBDB. The results indicated that the microcystins in the CBDB were successfully removed by KMnO{sub 4}. Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB, and formed manganese dioxide on the surface of CBDB. The oxidized CBDB showed higher adsorption capacity toward Cd(II) than that of unoxidized treatment. The optimal KMnO{sub 4} concentration for increasing the adsorption capacity of CBDB toward Cd(II) was 0.2 g/L. The adsorption isotherm of Cd(II) by oxidized- or unoxidized-CBDB was well fitted by Langmuir model, indicating that the adsorption of Cd(II) by CBDB was monolayer adsorption. The desorption ratio of Cd(II) from oxidized CBDB was higher than that from unoxidized CBDB in the desorption process using NH{sub 4}NO{sub 3} and EDTA as desorbent. The results presented in this study suggest that KMnO{sub 4} modified CBDB may be used as a safe and high efficient adsorbent in Cd(II) removal from water.

The effect of copper sulfate, potassium permanganate, and peracetic acid on Ichthyobodo necator in channel catfish

Science.gov (United States)

Ichthyobodo necator is a single celled biflagellate that can cause significant mortalities in fish, particularly young, tank-reared fish. Copper sulfate (CuSO4), potassium permanganate (KMnO4) and peracetic acid (PAA) were evaluated for effectiveness against Ichthybodosis in juvenile channel catfis...

Durability of template-free Fe-N-C foams for electrochemical oxygen reduction in alkaline solution

Science.gov (United States)

Mufundirwa, Albert; Harrington, George F.; Smid, Břetislav; Cunning, Benjamin V.; Sasaki, Kazunari; Lyth, Stephen M.

2018-01-01

Due to the high cost and limited availability of platinum, the development of non-platinum-group metals (non-PGM) catalysts is of paramount importance. A promising alternative to Pt are Fe-N-C-based materials. Here we present the synthesis, characterization and electrochemistry of a template-free nitrogen-doped carbon foam, impregnated with iron. This low-cost and gram-scale method results in materials with micron-scale pore size and large surface area (1600 m2g-1). When applied as an oxygen reduction reaction (ORR) electrocatalyst in alkaline solution, the Fe-N-C foams display extremely high initial activity, slightly out-performing commercially available non-PGM catalysts (NCP-2000, Pajarito Powder). The load-cycle durability in alkaline solution is investigated, and the performance steadily degrades over 60,000 potential cycles, whilst the commercial catalyst is remarkably stable. The post-operation catalyst microstructure is elucidated by transmission electron microscopy (TEM), to provide insight into the degradation processes. The resulting images suggest that potential cycling leads to leaching of atomically dispersed Fe-N2/4 sites in all the catalysts, whereas encapsulated iron nanoparticles are protected.

Potentiometric flow injection system for determination of reductants using a polymeric membrane permanganate ion-selective electrode based on current-controlled reagent delivery.

Science.gov (United States)

Song, Wenjing; Ding, Jiawang; Liang, Rongning; Qin, Wei

2011-10-17

A polymeric membrane permanganate-selective electrode has been developed as a current-controlled reagent release system for potentiometric detection of reductants in flow injection analysis. By applying an external current, diffusion of permanganate ions across the polymeric membrane can be controlled precisely. The permanganate ions released at the sample-membrane interface from the inner filling solution of the electrode are consumed by reaction with a reductant in the sample solution thus changing the measured membrane potential, by which the reductant can be sensed potentiometrically. Ascorbate, dopamine and norepinephrine have been employed as the model reductants. Under the optimized conditions, the potential peak heights are proportional to the reductant concentrations in the ranges of 1.0×10(-5) to 2.5×10(-7)M for ascorbate, of 1.0×10(-5) to 5.0×10(-7)M for dopamine, and of 1.0×10(-5) to 5.0×10(-7)M for norepinephrine, respectively with the corresponding detection limits of 7.8×10(-8), 1.0×10(-7) and 1.0×10(-7)M. The proposed system has been successfully applied to the determination of reductants in pharmaceutical preparations and vegetables, and the results agree well with those of iodimetric analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Reduction of potassium permanganate solution by γ-irradiated sodium chloride [Paper No. RD-21

International Nuclear Information System (INIS)

Phansalkar, V.K.; Ravishankar, D.

1982-01-01

The dissolution of γ-irradiated sodium chloride in potassium permanganate solution results in the reduction of MnO 4 - ions. This has been inferred from spectrophotometric studies. This has been explained on the basis of interaction of colour centres with MnO 4 - ions. The extent to which MnO 4 - ions are reduced are found to vary with

Development of a Design Tool for Planning Aqueous Amendment Injection Systems Permanganate Design Tool

Science.gov (United States)

2010-08-01

CSTR continuously stirred tank reactors CT contact time EDB ethylene dibromide ESTCP Environmental Security Technology Certification Program...63 6.2 Simulating Oxidant Distribution Using a Series of CSTRs -------------------- 63 6.2.1 Model...SIMULATING OXIDANT DISTRIBUTION USING A SERIES OF CSTRS 6.2.1 MODEL DEVELOPMENT The transport and consumption of permanganate are simulated within the

Electrochemical and corrosion properties of carbon steel in simulated geological disposal environments

International Nuclear Information System (INIS)

Sugimoto, Katsuhisa

2011-01-01

This paper reviews electrochemical and corrosion studies on the application of carbon steel to an overpack container, which is used for the geological disposal of radioactive wastes. Deaerated alkaline Na 2 SO 4 -NaHCO 3 - NaCl solutions and bentonite soaked with the solutions are used as simulated geological disposal environments. Electrochemical studies show the corrosion of the steel in an early stage is the activation control. Corrosion rates are controlled by the composition of the solutions, alloying elements, and the structure of the steel. The rates decrease with time due to the formation of FeCO 3 (siderite) film on the steel. Immersion corrosion tests show general corrosion morphology. Average corrosion rates of long duration have been evaluated. Clear proofs of the initiation of localized corrosion, such as pitting, crevice corrosion, hydrogen embrittlement and stress-corrosion cracking, have not been reported. (author)

Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts

DEFF Research Database (Denmark)

Zhong, Lijie; Jensen, Jens Oluf; Cleemann, Lars Nilausen

2018-01-01

is still unclear compared with the well-recognized surface coordinated FeNx/C structure. Using the strong complexing effect of the iron component with anions, cyanide (CN−) in alkaline and thiocyanate (SCN−) in acidic media, the metal containing active sites are electrochemically probed. Three...

Synthesis and crystal structure of the cesium silver permanganate Cs_3Ag[MnO_4]_4

International Nuclear Information System (INIS)

Bauchert, Joerg M.; Henning, Harald; Schleid, Thomas

2012-01-01

After successful syntheses and structural refinements of the already known permanganates of cesium (Cs[MnO_4]) and silver (Ag[MnO_4]) we started to blend aqueous solutions of both components in various molar ratios. From crystallization experiments of these mixtures only three species of crystals with different chemical compositions were obtained: tricesium monosilver tetrakispermanganate (Cs_3Ag[MnO_4]_4) and, depending upon the respective ratio, either additional silver permanganate or surplus cesium permanganate, namely. The new title compound crystallizes in the orthorhombic space group Pnnm (no. 58) with two formula units per unit cell and cell dimensions of a = 764.53(4), b = 1883.57(9) and c = 584.34(3) pm. The crystal structure of Cs_3Ag[MnO_4]_4 consists of two crystallographically distinguishable cesium cations. (Cs1)"+ is surrounded by fourteen oxygen atoms constructing a slightly distorted bicapped hexagonal prism. These polyhedra are connected through edge-sharing with two other polyhedra of this kind to form chains along [001]. The chains are linked to each other via sixfold coordinated Ag"+ cations (d(Ag-O) = 238-246 pm), arranged in such a manner that they link three oxygen atoms of two cesium polyhedra, leading to a two-dimensional layer spreading out parallel to the (001) plane. Together with the two crystallographically different tetrahedral oxomanganate(VII) anions [MnO_4]"- (d(Mn-O) = 161-162 pm) the other kind of cesium cations ((Cs2)"+ with CN = 13) finally connect these layers three-dimensionally. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis, spectroscopic and electrochemical performance of pasted β-nickel hydroxide electrode in alkaline electrolyte

Science.gov (United States)

Shruthi, B.; Bheema Raju, V.; Madhu, B. J.

2015-01-01

β-Nickel hydroxide (β-Ni(OH)2) was successfully synthesized using precipitation method. The structure and property of the β-Ni(OH)2 were characterized by X-ray diffraction (XRD), Fourier Transform infra-red (FT-IR), Raman spectra and thermal gravimetric-differential thermal analysis (TG-DTA). The results of the FTIR spectroscopy and TG-DTA studies indicate that the β-Ni(OH)2 contains water molecules and anions. The microstructural and composition studies have been performed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. A pasted-type electrode is prepared using β-Ni(OH)2 powder as the active material on a nickel sheet as a current collector. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) studies were performed to evaluate the electrochemical performance of the β-Ni(OH)2 electrode in 6 M KOH electrolyte. CV curves showed a pair of strong redox peaks as a result of the Faradaic redox reactions of β-Ni(OH)2. The proton diffusion coefficient (D) for the present β-Ni(OH)2 electrode material is found to be 1.44 × 10-12 cm2 s-1. Further, electrochemical impedance studies confirmed that the β-Ni(OH)2 electrode reaction processes are diffusion controlled.

The improvement of boron-doped diamond anode system in electrochemical degradation of p-nitrophenol by zero-valent iron

International Nuclear Information System (INIS)

Zhu Xiuping; Ni Jinren

2011-01-01

Boron-doped diamond (BDD) electrodes are promising anode materials in electrochemical treatment of wastewaters containing bio-refractory organic compounds due to their strong oxidation capability and remarkable corrosion stability. In order to further improve the performance of BDD anode system, electrochemical degradation of p-nitrophenol were initially investigated at the BDD anode in the presence of zero-valent iron (ZVI). The results showed that under acidic condition, the performance of BDD anode system containing zero-valent iron (BDD-ZVI system) could be improved with the joint actions of electrochemical oxidation at the BDD anode (39.1%), Fenton's reaction (28.5%), oxidation–reduction at zero-valent iron (17.8%) and coagulation of iron hydroxides (14.6%). Moreover, it was found that under alkaline condition the performance of BDD-ZVI system was significantly enhanced, mainly due to the accelerated release of Fe(II) ions from ZVI and the enhanced oxidation of Fe(II) ions. The dissolved oxygen concentration was significantly reduced by reduction at the cathode, and consequently zero-valent iron corroded to Fe(II) ions in anaerobic highly alkaline environments. Furthermore, the oxidation of released Fe(II) ions to Fe(III) ions and high-valent iron species (e.g., FeO 2+ , FeO 4 2− ) was enhanced by direct electrochemical oxidation at BDD anode.

High performance nano-Ni/Graphite electrode for electro-oxidation in direct alkaline ethanol fuel cells

Science.gov (United States)

Soliman, Ahmed B.; Abdel-Samad, Hesham S.; Abdel Rehim, Sayed S.; Ahmed, Mohamed A.; Hassan, Hamdy H.

2016-09-01

Ni/Graphite electrocatalysts (Ni/G) are successfully prepared through electrodeposition of Ni from acidic (pH = 0.8) and feebly acidic (pH = 5.5) aqueous Ni (II) baths. The efficiencies of such electrodes are investigated as anodes for direct alkaline ethanol fuel cells through their ethanol electrooxidation cyclic voltammetric (CV) response in alkaline medium. A direct proportionality between the amount of the electrodeposited Ni and its CV response is found. The amounts of the deposited Ni from the two baths are recorded using the Electrochemical Quartz Crystal Microbalance (eQCM). The Ni/G electrodes prepared from the feebly acidic bath show a higher electrocatalytic response than those prepared from the acidic bath. Surface morphology of the Ni particles electrodeposited from feebly acidic bath appears in a nano-scale dimension. Various electrochemical experiments are conducted to confirm that the Ni/G ethanol electrooxidation CV response greatly depends on the pH rather than nickel ion concentration of the deposition bath. The eQCM technique is used to detect the crystalline phases of nickel as α-Ni(OH)2/γ-NiOOH and β-Ni(OH)2/β-NiOOH and their in-situ inter-transformations during the potentiodynamic polarization.

Study of poly(vinyl alcohol)/titanium oxide composite polymer membranes and their application on alkaline direct alcohol fuel cell

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lee, Kuo-Tong; Chien, Wen-Chen; Lin, Che-Tseng; Huang, Ching-An

The novel poly(vinyl alcohol)/titanium oxide (PVA/TiO 2) composite polymer membrane was prepared using a solution casting method. The characteristic properties of the PVA/TiO 2 composite polymer membrane were investigated by thermal gravimetric analysis (TGA), a scanning electron microscopy (SEM), a micro-Raman spectroscopy, a methanol permeability measurement and the AC impedance method. An alkaline direct alcohol (methanol, ethanol and isopropanol) fuel cell (DAFC), consisting of an air cathode based on MnO 2/C inks, an anode based on PtRu (1:1) black and a PVA/TiO 2 composite polymer membrane, was assembled and examined for the first time. The results indicate that the alkaline DAFC comprised of a cheap, non-perfluorinated PVA/TiO 2 composite polymer membrane shows an improved electrochemical performances. The maximum power densities of alkaline DAFCs with 4 M KOH + 2 M CH 3OH, 2 M C 2H 5OH and 2 M isopropanol (IPA) solutions at room temperature and ambient air are 9.25, 8.00, and 5.45 mW cm -2, respectively. As a result, methanol shows the highest maximum power density among three alcohols. The PVA/TiO 2 composite polymer membrane with the permeability values in the order of 10 -7 to 10 -8 cm 2 s -1 is a potential candidate for use on alkaline DAFCs.

Electrochemical DNA biosensor based on MNAzyme-mediated signal amplification

International Nuclear Information System (INIS)

Diao, Wei; Tang, Min; Ding, Xiaojuan; Zhang, Ye; Yang, Jianru; Cheng, Wenbin; Mo, Fei; Wen, Bo; Xu, Lulu; Yan, Yurong

2016-01-01

The authors describe an electrochemical sensing strategy for highly sensitive and specific detection of target (analyte) DNA based on an amplification scheme mediated by a multicomponent nucleic acid enzyme (MNAzyme). MNAzymes were formed by multicomponent complexes which produce amplified “output” signals in response to specific “input” signal. In the presence of target nucleic acid, multiple partial enzymes (partzymes) oligonucleotides are assembled to form active MNAzymes. These can cleave H0 substrate into two pieces, thereby releasing the activated MNAzyme to undergo an additional cycle of amplification. Here, the two pieces contain a biotin-tagged sequence and a byproduct. The biotin-tagged sequences are specifically captured by the detection probes immobilized on the gold electrode. By employing streptavidinylated alkaline phosphatase as an enzyme label, an electrochemical signal is obtained. The electrode, if operated at a working potential of 0.25 V (vs. Ag/AgCl) in solution of pH 7.5, covers the 100 pM to 0.25 μM DNA concentration range, with a 79 pM detection limit. In our perception, the strategy introduced here has a wider potential in that it may be applied to molecular diagnostics and pathogen detection. (author)

The impact of pre-oxidation with potassium permanganate on cyanobacterial organic matter removal by coagulation

Czech Academy of Sciences Publication Activity Database

Načeradská, Jana; Pivokonský, Martin; Pivokonská, Lenka; Barešová, Magdalena; Henderson, R.K.; Zamyadi, A.; Janda, V.

2017-01-01

Roč. 114, May (2017), s. 42-49 ISSN 0043-1354 Institutional support: RVO:67985874 Keywords : algal organic matter * coagulation * Microcystis aeruginosa * peptides/proteins * permanganate pre-oxidation * water treatment Subject RIV: DJ - Water Pollution ; Quality OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 6.942, year: 2016

Rebound of a coal tar creosote plume following partial source zone treatment with permanganate.

Science.gov (United States)

Thomson, N R; Fraser, M J; Lamarche, C; Barker, J F; Forsey, S P

2008-11-14

The long-term management of dissolved plumes originating from a coal tar creosote source is a technical challenge. For some sites stabilization of the source may be the best practical solution to decrease the contaminant mass loading to the plume and associated off-site migration. At the bench-scale, the deposition of manganese oxides, a permanganate reaction byproduct, has been shown to cause pore plugging and the formation of a manganese oxide layer adjacent to the non-aqueous phase liquid creosote which reduces post-treatment mass transfer and hence mass loading from the source. The objective of this study was to investigate the potential of partial permanganate treatment to reduce the ability of a coal tar creosote source zone to generate a multi-component plume at the pilot-scale over both the short-term (weeks to months) and the long-term (years) at a site where there is >10 years of comprehensive synoptic plume baseline data available. A series of preliminary bench-scale experiments were conducted to support this pilot-scale investigation. The results from the bench-scale experiments indicated that if sufficient mass removal of the reactive compounds is achieved then the effective solubility, aqueous concentration and rate of mass removal of the more abundant non-reactive coal tar creosote compounds such as biphenyl and dibenzofuran can be increased. Manganese oxide formation and deposition caused an order-of-magnitude decrease in hydraulic conductivity. Approximately 125 kg of permanganate were delivered into the pilot-scale source zone over 35 days, and based on mass balance estimates 35% reduction for all monitored compounds except for biphenyl, dibenzofuran and fluoranthene 150 days after treatment, which is consistent with the bench-scale experimental results. Pre- and post-treatment soil core data indicated a highly variable and random spatial distribution of mass within the source zone and provided no insight into the mass removed of any of the

Low temperature thermal annealing in fast neutron-irradiated potassium permanganate

Energy Technology Data Exchange (ETDEWEB)

Owens, C W; Lecington, W C [New Hampshire Univ., Durham (USA). Dept. of Chemistry

1975-01-01

The effect of thermal annealing on the retention of recoil /sup 54/Mn as permanganate in crystalline KMnO/sub 4/ irradiated with fast neutrons at liquid nitrogen temperature has been studied. The retention after 4 hrs of annealing increases from about 8% at -196/sup 0/ to a maximum of 61% at 180/sup 0/, then decreases at higher temperatures. A single activation energy (approximately 0.01 eV) applies to the thermal annealing process between -196/sup 0/ and -40/sup 0/. Extrapolation of the data suggests that below -229/sup 0/ no thermal annealing would occur.

A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

Science.gov (United States)

Kelland, Malcolm A.

2011-01-01

Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

Nitrate removal from alkaline high nitrate effluent by in situ generation of hydrogen using zinc dust

International Nuclear Information System (INIS)

Rajagopal, S.; Chitra, S.; Paul, Biplob

2016-01-01

Alkaline radioactive low level waste generated in Nuclear Fuel Cycle contains substantial amount of nitrate and needs to be treated to meet Central Pollution Control Board discharge limits of 90 mg/L in marine coastal area. Several denitrification methods like chemical treatment, electrochemical reduction, biological denitrification, ion exchange, reverse osmosis, photochemical reduction etc are followed for removal of nitrate. In effluent treatment plants where chemical treatment is carried out, chemical denitrification can be easily adapted without any additional set up. Reducing agents like zinc and aluminum are suitable for reducing nitrate in alkaline solution. Study on denitrification with zinc dust was taken up in this work. Not much work has been done with zinc dust on reduction of nitrate to nitrogen in alkaline waste with high nitrate content. In the present work, nitrate is reduced by nascent hydrogen generated in situ, caused by reaction between zinc dust and sodium hydroxide

A disposable electrochemical immunosensor for prolactin involving affinity reaction on streptavidin-functionalized magnetic particles

International Nuclear Information System (INIS)

Moreno-Guzman, Maria; Gonzalez-Cortes, Araceli; Yanez-Sedeno, Paloma; Pingarron, Jose M.

2011-01-01

A novel electrochemical immunosensor was developed for the determination of the hormone prolactin. The design involved the use of screen-printed carbon electrodes and streptavidin-functionalized magnetic particles. Biotinylated anti-prolactin antibodies were immobilized onto the functionalized magnetic particles and a sandwich-type immunoassay involving prolactin and anti-prolactin antibody labelled with alkaline phosphatase was employed. The resulting bio-conjugate was trapped on the surface of the screen-printed electrode with a small magnet and prolactin quantification was accomplished by differential pulse voltammetry of 1-naphtol formed in the enzyme reaction using 1-naphtyl phosphate as alkaline phosphatase substrate. All variables involved in the preparation of the immunosensor and in the electrochemical detection step were optimized. The calibration plot for prolactin exhibited a linear range between 10 and 2000 ng mL -1 with a slope value of 7.0 nA mL ng -1 . The limit of detection was 3.74 ng mL -1 . Furthermore, the modified magnetic beads-antiprolactin conjugates showed an excellent stability. The immunosensor exhibited also a high selectivity with respect to other hormones. The analytical usefulness of the immnunosensor was demonstrated by analyzing human sera spiked with prolactin at three different concentration levels.

A disposable electrochemical immunosensor for prolactin involving affinity reaction on streptavidin-functionalized magnetic particles

Energy Technology Data Exchange (ETDEWEB)

Moreno-Guzman, Maria; Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, 28040 Madrid (Spain); Yanez-Sedeno, Paloma, E-mail: yseo@quim.ucm.es [Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, 28040 Madrid (Spain); Pingarron, Jose M. [Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, 28040 Madrid (Spain)

2011-04-29

A novel electrochemical immunosensor was developed for the determination of the hormone prolactin. The design involved the use of screen-printed carbon electrodes and streptavidin-functionalized magnetic particles. Biotinylated anti-prolactin antibodies were immobilized onto the functionalized magnetic particles and a sandwich-type immunoassay involving prolactin and anti-prolactin antibody labelled with alkaline phosphatase was employed. The resulting bio-conjugate was trapped on the surface of the screen-printed electrode with a small magnet and prolactin quantification was accomplished by differential pulse voltammetry of 1-naphtol formed in the enzyme reaction using 1-naphtyl phosphate as alkaline phosphatase substrate. All variables involved in the preparation of the immunosensor and in the electrochemical detection step were optimized. The calibration plot for prolactin exhibited a linear range between 10 and 2000 ng mL{sup -1} with a slope value of 7.0 nA mL ng{sup -1}. The limit of detection was 3.74 ng mL{sup -1}. Furthermore, the modified magnetic beads-antiprolactin conjugates showed an excellent stability. The immunosensor exhibited also a high selectivity with respect to other hormones. The analytical usefulness of the immnunosensor was demonstrated by analyzing human sera spiked with prolactin at three different concentration levels.

Corrosion of conductive polypyrrole: Effects of environmental factors, electrochemical stimulation, and doping anions

International Nuclear Information System (INIS)

Qi Kai; Qiu Yubing; Chen Zhenyu; Guo Xingpeng

2012-01-01

Highlights: ► Corrosive galvanic cells form on PPy film with the electrochemical reduction of O 2. ► Suitable electrochemical stimulation can inhibit the PPy’s corrosion. ► PPy film doped with larger sized anions has better corrosion resistance performance. - Abstract: The effects of environmental factors, electrochemical stimulation, and doping anions on the corrosion behaviour of conductive polypyrrole (PPy) films in alkaline aqueous media were studied with cyclic voltammetry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. High concentrations of electrolyte, low dissolved oxygen and low temperatures enhance the stability of PPy. Polarising PPy at a negative potential inhibits its corrosion obviously. PPy doped with large counter anions shows better corrosion resistance than PPy doped with small counter ions. The possible mechanism involved in PPy corrosion process is discussed.

Properties of cathode materials in alkaline cells

International Nuclear Information System (INIS)

Salkind, A.J.; McBreen, J.; Freeman, R.; Parkhurst, W.A.

1985-01-01

Conventional and new cathode materials in primary and secondary alkaline cells were investigated for stability, structure, electrochemical reversibility and efficiency. Included were various forms of AgO for reserve-type silver-zinc batteries, a new material - AgNiO/sub 2/ - and several nickel electrodes for nickel-cadmium and nickel-hydrogen cells for aerospace applications. A comparative study was made of the stability of electroformed and chemically prepared AgO. Stability was correlated with impurities detected by XPS and SAM. After the first discharge AgNiO/sub 2/ can be recharged to the monovalent level. The discharge product is predominantly silver. Plastic-bonded nickel electrodes display a second plateau on discharge. Additions of Co(OH)/sub 2/ largely eliminate this

Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media

Directory of Open Access Journals (Sweden)

Nagappan Ramaswamy

2012-01-01

Full Text Available Complex electrochemical reactions such as Oxygen Reduction Reaction (ORR involving multi-electron transfer is an electrocatalytic inner-sphere electron transfer process that exhibit strong dependence on the nature of the electrode surface. This criterion (along with required stability in acidic electrolytes has largely limited ORR catalysts to the platinum-based surfaces. New evidence in alkaline media, discussed here, throws light on the involvement of surface-independent outer-sphere electron transfer component in the overall electrocatalytic process. This surface non-specificity gives rise to the possibility of using a wide-range of non-noble metal surfaces as electrode materials for ORR in alkaline media. However, this outer-sphere process predominantly leads only to peroxide intermediate as the final product. The importance of promoting the electrocatalytic inner-sphere electron transfer by facilitation of direct adsorption of molecular oxygen on the active site is emphasized by using pyrolyzed metal porphyrins as electrocatalysts. A comparison of ORR reaction mechanisms between acidic and alkaline conditions is elucidated here. The primary advantage of performing ORR in alkaline media is found to be the enhanced activation of the peroxide intermediate on the active site that enables the complete four-electron transfer. ORR reaction schemes involving both outer- and inner-sphere electron transfer mechanisms are proposed.

Kinetic studies of potassium permanganate adsorption by activated carbon and its ability as ethylene oxidation material

Science.gov (United States)

Aprilliani, F.; Warsiki, E.; Iskandar, A.

2018-03-01

Generally, ethylene production in many horticultural products has been seen to be detrimental to the quality during storage and distribution process. For this reason, removing ethylene from storage or distribution atmosphere is needed to maintain the quality. One of the technologies that can be applied is the use of potassium permanganate (KMnO4). KMnO4 is an active compound that can be used as an oxidizing agent on ethylene removal process. KMnO4 is not recommended for direct used application. As the result, additional material is required to impregnate the potassium permanganate. The inert materials used are commercial activated carbon. Activated carbon is chosen because it has high surface area. The purpose of this research is to determine kinetics adsorption and oxidation model of ethylene removal material. The kinetics adsorption was determined using the pseudo-first and second-order kinetic models. The data on adsorption process show that the second-order equation is more suitable to express the adsorption process on this research. The analyzing of the ethylene oxidation capacity increased with time until it reaches an optimal value. The ethylene oxidation rate is able to be estimated by the formula r = 0.1967 [C2H4]0.99 [KMnO4]0.01; MSE = 0.44 %. The actual and estimation data of ethylene oxidation show that the model is fitted to describe the actual ethylene oxidation under same experimental conditions.

Spectrophotometric Determination of Aminoglycoside Antibiotics Based on their Oxidation by Potassium Permanganate

International Nuclear Information System (INIS)

El-Didamony, A. M.; Ghoneim, A. K.; Telebany, A. M.; Amin, A. S.

2006-01-01

A rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of neomycin and streptomycin either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C), and methylene blue (method D), in the same acid medium at a suitable λ max =521, 485, 610 and 664 nm, respectively. Beer's law is obeyed in the concentration range of 5-10 and 2-7 mg mL -1 for neomycin and streptomycin, respectively. The apparent molar absorptivity and sandell sensitivity values are in the range 5.47-6.20x10 4 , 2.35-2.91x10 5 L mol -1 cm -1 and 7.57-8.59, 5.01-6.2 ng cm -2 for neomycin and streptomycin, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs either in a pure or pharmaceutical dosage forms with good accuracy and precision. No interferences were observed from excipients and the results obtained were in good agreement with those obtained using the official methods

One–pot synthesis and electrochemical properties of polyaniline nanofibers through simply tuning acid–base environment of reaction medium

International Nuclear Information System (INIS)

Li, Tao; Zhou, Yi; Liang, Banglei; Jin, Dandan; Liu, Na; Qin, Zongyi; Zhu, Meifang

2017-01-01

Highlights: •Presenting a facile one–pot approach to prepare polyaniline nanofibers through simply tuning acid–base environment of reaction medium. •Determining the role of aniline oligomers play in the formation of polyaniline nanofibers. •Demonstrating the feasibility of polyaniline nanofibers as high–performance electrode materials for supercapacitors. -- Abstract: A facile and efficient one–pot approach was presented to prepare polyaniline (PANi) nanofibers through simply tuning acid–base environment of reaction medium without the assistance of templates or use of organic solvents, in which aniline oligomers formed in the alkaline solution were used as “seeds” for the oriented growth of PANi chains under acidic conditions. The as–prepared PANi nanofibers were investigated by field–emission scanning electron microscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy and X–ray diffraction technology. Furthermore, the electrochemical properties were evaluated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy. More attentions were paid to the influence of aniline concentrations in alkaline and acidic reaction medium on the morphology, microstructure and properties of PANi nanofibers. It can be found that aniline concentration in alkaline medium has a stronger impact on the electrical and electrochemical properties of final products, however, their morphologies obviously depend on aniline concentration in acidic solution. Moreover, PANi nanofibers prepared at aniline concentrations of 48 mM in alkaline medium and 0.2 M in acidic medium exhibits the largest specific capacitance of 857.2 F g −1 at the scan rate of 5 mV s −1 , and capacitance retention of 63.8% after 500 cycles. It is demonstrated that such one–pot approach can present a low cost and environmental friendly route to fabricate PANi nanofibers in fully aqueous solution as high�

Electrochemical performance of an air-breathing direct methanol fuel cell using poly(vinyl alcohol)/hydroxyapatite composite polymer membrane

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lin, Che-Tseng

A novel composite polymer membrane based on poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) was successfully prepared by a solution casting method. The characteristic properties of the PVA/HAP composite polymer membranes were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and AC impedance method. An air-breathing DMFC, comprised of an air cathode electrode with MnO 2/BP2000 carbon inks on Ni-foam, an anode electrode with PtRu black on Ti-mesh, and the PVA/HAP composite polymer membrane, was assembled and studied. It was found that this alkaline DMFC showed an improved electrochemical performance at ambient temperature and pressure; the maximum peak power density of an air-breathing DMFC in 8 M KOH + 2 M CH 3OH solution is about 11.48 mW cm -2. From the application point of view, these composite polymer membranes show a high potential for the DMFC applications.

Electrochemical performance of an air-breathing direct methanol fuel cell using poly(vinyl alcohol)/hydroxyapatite composite polymer membrane

Energy Technology Data Exchange (ETDEWEB)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lin, Che-Tseng [Department of Chemical Engineering, Mingchi University of Technology, Taipei Hsien 243 (China)

2008-02-15

A novel composite polymer membrane based on poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) was successfully prepared by a solution casting method. The characteristic properties of the PVA/HAP composite polymer membranes were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and AC impedance method. An air-breathing DMFC, comprised of an air cathode electrode with MnO{sub 2}/BP2000 carbon inks on Ni-foam, an anode electrode with PtRu black on Ti-mesh, and the PVA/HAP composite polymer membrane, was assembled and studied. It was found that this alkaline DMFC showed an improved electrochemical performance at ambient temperature and pressure; the maximum peak power density of an air-breathing DMFC in 8 M KOH + 2 M CH{sub 3}OH solution is about 11.48 mW cm{sup -2}. From the application point of view, these composite polymer membranes show a high potential for the DMFC applications. (author)

Alkalinity in oil field waters - what alkalinity is and how it is measured

International Nuclear Information System (INIS)

Kaasa, B.; Oestvold, T.

1996-01-01

The alkalinity is an important parameter in the description of pH-behaviour, buffer capacity and scaling potentials in oil field waters. Although the alkalinity is widely used, it seems to be considerable confusion in connection with the concept. It is often used incorrectly and different authors define the concept in different ways. Several different methods for the determination of alkalinity can be found in the literature. This paper discusses the definition of alkalinity and how to use alkalinity in oil field waters to obtain data of importance for scale and pH predictions. There is also shown how a simple titration of oil field waters can give both the alkalinity and the content of organic acids in these waters. It is obvious from these findings that most of the methods used to day may give considerable errors when applied to oil field waters with high contents of organic acids. 8 refs., 8 figs., 5 tabs

Flow-injection chemiluminescent determination of estrogen benzoate using the tris(1,10-phenanthroline) ruthenium(II)-permanganate system.

Science.gov (United States)

Ma, Yan; Cao, Wei; Qiao, Shuang; Liu, Wenwen; Yang, Jinghe

2011-01-01

Chemiluminescence (CL) detection for the determination of estrogen benzoate, using the reaction of tris(1,10-phenanthroline)ruthenium(II)-Na(2)SO(3)-permanganate, is described. This method is based on the CL reaction of estrogen benzoate (EB) with acidic potassium permanganate and tris(1,10-phenanthroline)ruthenium(II). The CL intensity is greatly enhanced when Na(2)SO(3) is added. After optimization of the different experimental parameters, a calibration graph for estrogen benzoate is linear in the range 0.05-10 µg/mL. The 3 s limit of detection is 0.024 µg/mL and the relative standard deviation was 1.3% for 1.0 µg/mL estrogen benzoate (n = 11). This proposed method was successfully applied to commercial injection samples and emulsion cosmetics. The mechanism of CL reaction was also studied. Copyright © 2011 John Wiley & Sons, Ltd.

Technological development and prospect of alkaline fuel cells

International Nuclear Information System (INIS)

Meng Ni; Michael KH Leung; Dennis YC Leung

2006-01-01

This paper reviewed the technological development of alkaline fuel cell (AFC). Although the technology was popular in 1970's and 1980's, there has been a decline in AFC research over the past decade, mainly due to the poisoning of CO 2 . Continuous efforts have demonstrated that CO 2 concentration could be reduced to an acceptable level by a number of viable methods such as absorption, adsorption, electrochemical process, electrolyte circulation, use of liquid hydrogen, and use of solid anionic exchange membranes. Literature survey showed that AFC lifetime could achieve up to 5000 hours. In addition, the use of ammonia as a fuel for AFC was identified as a promising technology. Comparison between AFC and proton exchange membrane fuel cell (PEMFC) was presented to evaluate the AFC technology and its economics. The present review and assessment showed the promise of AFC for the coming hydrogen economy and sustainable development. (authors)

The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence.

Science.gov (United States)

Holland, Brendan J; Adcock, Jacqui L; Nesterenko, Pavel N; Peristyy, Anton; Stevenson, Paul G; Barnett, Neil W; Conlan, Xavier A; Francis, Paul S

2014-09-09

Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV). Copyright © 2014 Elsevier B.V. All rights reserved.

Alkaline protease production on date waste by an alkalophilic ...

African Journals Online (AJOL)

STORAGESEVER

2008-05-16

May 16, 2008 ... After 72 h incubation in a shaker incubator ... different incubation times (0 to 72 h) were investigated. Alkaline .... of alkaline protease (75%) and 24% of total protein is precipitated. ... starches and wheat flour as carbon source on protease production .... JP 395, method of making and detergent composition.

Experimental investigations on potassium permanganate doped polyvinyl alcohol - polyvinyl pyrrolidone blend

Science.gov (United States)

Veena, G.; Lobo, Blaise

2018-04-01

Potassium permanganate (KMnO4) doped polyvinyl alcohol (PVA) - polyvinyl pyrrolidone (PVP) blend films were prepared by solution casting technique, in the doping range varying from 0.01 wt % up to 4.70 wt %. The microstructural changes caused by doping, and the modified properties of these films were studied using Atomic Force Microscope (AFM) and temperature dependent direct current (DC) electrical measurements. Temperature variation of electrical resistivity was found to obey Arrhenius relation, from which activation energy was determined. The study was supported by AFM scans, which showed an increase in surface roughness and the presence of spike-like structures, due to interaction of dopant with the polymeric blend. Differential Scanning Calorimetry (DSC) scans revealed two stages of degradation in KMnO4 doped PVA - PVP blend films.

Indirect spectrophotometric determination of piroxicam and tenoxicam through oxidation with potassium permanganate

OpenAIRE

A.S. Amin; H.A. Dessouki; K.M. Khalil

2010-01-01

Three rapid, simple, accurate and selective validated spectrophtometric methods (A, B and C) for the determination of piroxicam (PX) and tenoxicam (TX) in bulk sample and in dosage forms are described. The methods are based on the oxidation of the studied drugs by a known excess of potassium permanganate in sulfuric acid medium and subsequent determination of unreacted oxidant by reacting it with Methylene Blue (Basic Blue 9) dye (method A), Acid Red 27 (Amaranth) dye (method B) and Acid Oran...

Impact of Strontium Nitrate and Sodium Permanganate Addition on Solid-Liquid Separation of SRS High Level Waste

International Nuclear Information System (INIS)

Poirier, M.R.

2002-01-01

As a pretreatment step for the caustic side solvent extraction (CSSX) flowsheet, the process contacts the incoming salt solution containing entrained sludge with monosodium titanate (MST) to adsorb strontium and actinides. An operation filters the resulting slurry to remove the sludge and MST. Previous work for the River Protection Program at Hanford suggests that addition of strontium nitrate and sodium permanganate for strontium and actinide removal, rather than MST, improves the filtration rate for comparable waste streams

An alkaline separation method for detection of small amount of DNA damage

International Nuclear Information System (INIS)

Sakai, Kazuo; Okada, Shigefumi

1981-01-01

An alkaline separation technique originally established by Ahnstroem is modified to detect small amount of DNA damage in X-irradiated mouse leukemic L5178Y cells. It is made quantitative by calibration with an alkaline sucrose gradient centrifugation. The present method would make it possible to study DNA damage and its repair within a dose range of X-rays where cell survival and mutation are usually investigated. It is also useful for detecting DNA damage caused by chemicals. (author)

Electrochemical power sources batteries, fuel cells, and supercapacitors

CERN Document Server

Bagotsky, Vladimir S; Volfkovich, Yurij M

2015-01-01

Electrochemical Power Sources (EPS) provides in a concise way theoperational features, major types, and applications of batteries,fuel cells, and supercapacitors Details the design, operational features, andapplications of batteries, fuel cells, and supercapacitors Covers improvements of existing EPSs and thedevelopment of new kinds of EPS as the results of intense R&Dwork Provides outlook for future trends in fuel cells andbatteries Covers the most typical battery types, fuel cells andsupercapacitors; such as zinc-carbon batteries, alkaline manganesedioxide batteries, mercury-zinc cells, lead

Electrochemical oxidation of iron and alkalinity generation for efficient sulfide control in sewers.

Science.gov (United States)

Lin, Hui-Wen; Kustermans, Caroline; Vaiopoulou, Eleni; Prévoteau, Antonin; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

2017-07-01

The addition of iron salts is one of the most commonly used dosing strategies for sulfide control in sewers. However, iron salts decrease the sewage pH which not only reduces the effectiveness of sulfide precipitation but also enhances the release of residual sulfide to the sewer atmosphere. Equally important, concentrated iron salt solutions are corrosive and their frequent transport, handling, and on-site storage often come with Occupational Health and Safety (OH&S) concerns. Here, we experimentally demonstrated a novel sulfide control approach using electrochemical systems with parallel placed iron electrodes. This enabled combining anodic dissolved iron species release with cathodic hydroxyl anion production, which alleviates all the aforementioned concerns. A long-term experiment was successfully carried out achieving an average sulfide removal efficiency of 95.4 ± 4.4% at low voltage input of 2.90 ± 0.54 V over the course of 8 weeks. This electrochemical method was demonstrated to successfully achieve efficient sulfide control. In addition, it increases the sewage pH, thereby overcoming the drawbacks associated with the pH decrease in the case of conventional iron salt dosing. Ferrous ions were produced at an overall coulombic efficiency (CE) of 98.2 ± 1.2%, whereas oxygen evolution and direct sulfide oxidation were not observed. Short-term experiments showed that increasing either inter-electrode gap or current density increased the cell voltage associated with the increase in the ohmic drop of the system. Overall, this study highlights the practical potential of in-situ generation of dissolved iron species and simultaneous hydroxyl anion generation for efficient sulfide control in sewers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of steel passivation in inhibited cooling waters by electrochemical impedance spectroscopy

International Nuclear Information System (INIS)

Gusmano, G.; Montesperelli, G.; Traversa, E.

1992-01-01

The corrosion of mild steel, which is one of the main problems in industrial cooling equipments, is greatly influenced by total alkalinity, pH and oxygen concentration. The low concentration of oxygen present in natural waters and the low solubility of CaCO 3 greatly affect the passivation mechanism, hindering the growth of a compact and protective film. The all-organic inhibitors, which have the property of supersaturating waters with CaCO 3 , overcome this problem. In this paper the electrical characteristics of the protective film formed by this kind of inhibitors in the presence of different levels of carbonatic alkalinity and at different pH values is studied by Electrochemical Impedance Spectroscopy

Electrochemical Behavior Assessment of As-Cast Mg-Y-RE-Zr Alloy in Phosphate Buffer Solutions (X Na3PO4 + Y Na2HPO4) Using Electrochemical Impedance Spectroscopy and Mott-Schottky Techniques

Science.gov (United States)

Fattah-alhosseini, Arash; Asgari, Hamed

2018-05-01

In the present study, electrochemical behavior of as-cast Mg-Y-RE-Zr alloy (RE: rare-earth alloying elements) was investigated using electrochemical tests in phosphate buffer solutions (X Na3PO4 + Y Na2HPO4). X-ray diffraction techniques and Scanning electron microscopy equipped with energy dispersive x-ray spectroscopy were used to investigate the microstructure and phases of the experimental alloy. Different electrochemical tests such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis were carried out in order to study the electrochemical behavior of the experimental alloy in phosphate buffer solutions. The PDP curves and EIS measurements indicated that the passive behavior of the as-cast Mg-Y-RE-Zr alloy in phosphate buffer solutions was weakened by an increase in the pH, which is related to formation of an imperfect and less protective passive layer on the alloy surface. The presence of the insoluble zirconium particles along with high number of intermetallic phases of RE elements mainly Mg24Y5 in the magnesium matrix can deteriorate the corrosion performance of the alloy by disrupting the protective passive layer that is formed at pH values over 11. These insoluble zirconium particles embedded in the matrix can detrimentally influence the passivation. The M-S analysis revealed that the formed passive layers on Mg-Y-RE-Zr alloy behaved as an n-type semiconductor. An increase in donor concentration accompanying solutions of higher alkalinity is thought to result in the formation of a less resistive passive layer.

Cobalt hydroxide film on Pt as co-catalyst for oxidation of polyhydric alcohols in alkaline medium

International Nuclear Information System (INIS)

Das, Debasmita; Das, Kaushik

2010-01-01

Electrochemical behavior of chemically prepared Co(OH) 2 film on Pt has been studied in alkaline medium using cyclic voltammetry and chronoamperometry. Amount of Co(OH) 2 deposited increases linearly with the number of times of deposition. The deposit is of fibrous structure, as shown by scanning electron microphotograph. There is evidence of Co II /Co III and Co III /Co IV redox transitions during the cyclic potential scan. The former oxidation proceeds under diffusion control. The Co(OH) 2 deposit acts as an efficient co-catalyst for anodic oxidation of ethanediol, propanediol and glycerol on Pt in alkaline medium. This is demonstrated by appreciable enhancement of the alcohol oxidation currents upon deposition of Co(OH) 2 on Pt. Among the alcohols studied, the highest oxidation currents are obtained for ethanediol, both on Co(OH) 2 /Pt and bare Pt. Co(OH) 2 alone also acts as a redox mediator for alcohol oxidation at more positive potentials.

Method of bonding an interconnection layer on an electrode of an electrochemical cell

Science.gov (United States)

Pal, Uday B.; Isenberg, Arnold O.; Folser, George R.

1992-01-01

An electrochemical cell containing an air electrode (16), contacting electrolyte and electronically conductive interconnection layer (26), and a fuel electrode, has the interconnection layer (26) attached by: (A) applying a thin, closely packed, discrete layer of LaCrO.sub.3 particles (30), doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg and their mixtures on a portion of the air electrode, and then (B) electrochemical vapor depositing a dense skeletal structure (32) between and around the doped LaCrO.sub.3 particles (30).

An in situ Fourier transform infrared spectroelectrochemical study on ethanol electrooxidation on Pd in alkaline solution

Energy Technology Data Exchange (ETDEWEB)

Fang, Xiang; Wang, Lianqin; Shen, Pei Kang [The State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Cui, Guofeng [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Bianchini, Claudio [Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy)

2010-03-01

The mechanism of ethanol electrooxidation on a palladium electrode in alkaline solution (from 0.01 to 5 M NaOH) has been investigated by cyclic voltammetry and in situ Fourier transform infrared spectroelectrochemistry. The electrode performance has been found to depend on the pH of the fuel solution. The best performance was observed in 1 M NaOH solution (pH = 14), while the electrochemical activity decreased by either increasing or decreasing the NaOH concentration. In situ FTIR spectroscopic measurements showed the main oxidation product to be sodium acetate at NaOH concentrations higher than 0.5 M. The C-C bond cleavage of ethanol, put in evidence by the formation of CO{sub 2}, occurred at pH values {<=}13. In these conditions, however, the catalytic activity for ethanol oxidation was quite low. No CO formation was detected along the oxidation of ethanol by FTIR spectroscopy. (author)

Electrochemical depth profiling of multilayer metallic structures: An aluminum brazing sheet

International Nuclear Information System (INIS)

Afshar, F. Norouzi; Ambat, R.; Kwakernaak, C.; Wit, J.H.W. de; Mol, J.M.C.; Terryn, H.

2012-01-01

Highlights: ► Localized electrochemical cell and glow discharge optical emission spectrometry were used. ► An electrochemical depth profile of an aluminum brazing sheet was obtained. ► The electrochemical responses were correlated to the microstructural features. - Abstract: Combinatory localized electrochemical cell and glow discharge optical emission spectrometry (GDOES) measurements were performed to obtain a thorough in depth electrochemical characterization of an aluminum brazing sheet. By defining electrochemical criteria i.e. breakdown potential, corrosion potential, cathodic and anodic reactivities, and tracking their changes as a function of depth, the evolution of electrochemical responses through out the material thickness were analyzed and correlated to the corresponding microstructural features. Polarization curves in 1 wt% NaCl solution at pH 2.8 were obtained at different depths from the surface using controlled sputtering in a glow discharge optical emission spectrometer as a sample preparation technique. The anodic and cathodic reactivity of the top surface areas were significantly higher than that of the bulk, thus indicating these areas to be more susceptible to localized attack. Consistent with this, optical microscopy and scanning electron microscope analysis revealed a relatively high density of fine intermetallic and silicon particles at these areas. The corrosion mechanism of the top layers was identified to be intergranular and pitting corrosion, while lower sensitivity to these localized attacks were detected toward the brazing sheet core. The results highlight the successful application of the electrochemical depth profiling approach in prediction of the corrosion behavior of the aluminum brazing sheet and the importance of the electrochemical activity of the outer 10 μm in controlling the corrosion performance of the aluminum brazing sheet.

Application of ascorbic acid 2-phosphate as a new voltammetric substrate for alkaline phosphatase determination in human serum

Directory of Open Access Journals (Sweden)

Wei Sun

2005-12-01

Full Text Available An electrochemical assay of the enzyme alkaline phosphatase (ALP using ascorbic acid 2-phosphate (AAP as a new voltammetric substrate has been described in this paper. In the alkaline buffer solution the ALP enzymatic hydrolysis product of AAP was ascorbic acid (AA, which was an electro-active substance and had a sensitive differential pulse voltammetric (DPV oxidative response on glassy carbon electrode (GCE at +380 mV (versus Ag/AgCl, so the activity of ALP could be monitored voltammetrically of the oxidative peak current of AA. The electrochemical behaviours of AA were carefully studied and the AA standard solution could be measured by DPV method in the linear range from 10.0 to 1000.0 μmol/L with the detection limit of 8.0 μmol/L. The optimal conditions for ALP enzymatic reaction and the voltammetric detection were optimized. Under the optimal conditions the calibration curve for ALP assay exhibited a linear range from 0.4 to 2000.0 U/L with a detection limit of 0.3 U/L. This proposed method was further applied to determine the ALP content in healthy human serum and the results were in good agreement with the traditional p-nitrophenyl phosphate spectrophotometric method. The kinetic constants of enzymatic reaction were also investigated with the apparent kinetic constant Km as 2.77 mmol/L and the maximum velocity Vmax as 0.33 mol/min.

Layer-by-layer self-assembled two-dimensional MXene/layered double hydroxide composites as cathode for alkaline hybrid batteries

Science.gov (United States)

Dong, Xiaowan; Zhang, Yadi; Ding, Bing; Hao, Xiaodong; Dou, Hui; Zhang, Xiaogang

2018-06-01

Multifarious layered materials have received extensive concern in the field of energy storage due to their distinctive two-dimensional (2D) structure. However, the natural tendency to be re-superimposed and the inherent disadvantages of a single 2D material significantly limit their performance. In this work, the delaminated Ti3C2Tx (d-Ti3C2Tx)/cobalt-aluminum layered double hydroxide (Ti3C2Tx/CoAl-LDH) composites are prepared by layer-by-layer self-assembly driven by electrostatic interaction. The alternate Ti3C2Tx and CoAl-LDH layers prevent each other from restacking and the obtained Ti3C2Tx/CoAl-LDH heterostructure combine the advantages of high electron conductivity of Ti3C2Tx and high electrochemical activity of CoAl-LDH, thus effectively improving the electrochemical reactivity of electrode materials and accelerating the kinetics of Faraday reaction. As a consequence, as a cathode for alkaline hybrid battery, the Ti3C2Tx/CoAl-LDH electrode exhibits a high specific capacity of 106 mAh g-1 at a current density of 0.5 A g-1 and excellent rate capability (78% at 10 A g-1), with an excellent cycling stability of 90% retention after 5000 cycles at 4 A g-1. This work provides an alternative route to design advanced 2D electrode materials, thus exploiting their full potentials for alkaline hybrid batteries.

Oxidative Degradation of Phenol containing Wastewater using Fenton Reagent, Permanganate and Ultraviolet Radiation

International Nuclear Information System (INIS)

Abd El-Rahman, N.M.; Talaat, H.A.; Sorour, M.H.

1999-01-01

Phenol containing wastewaters are generated by numerous industrial units including integrated steel mills, textile mills, plastic production, etc. The present work is targeted to explore the viable oxidation techniques for degradation of phenolic wastewater. Three modes of treatment have been adopted in this study, namely, sole oxidant mode using Fenton reagent or permanganate, UV-assisted oxidation and two consequent chemical oxidation steps. Results indicated the superiority of fenton reagent over KMnO 4 oxidation in the sole oxidant mode. On the other hand, UV-assisted KMnO 4 oxidation enables almost complete COD reduction. Dual chemical oxidation mode employing KMnO 4 oxidation followed by Fenton reagent is also an efficient oxidative degradation system

Novel inorganic materials for polymer electrolyte and alkaline fuel cells

Science.gov (United States)

Tadanaga, Kiyoharu

2012-06-01

Inorganic materials with high ionic conductivity must have big advantages for the thermal and long term stability when the materials are used as the electrolyte of fuel cells. In the present paper, novel ionic conductive inorganic materials for polymer electrolyte fuel cells (PEFCs) and all solid state alkaline fuel cells (AFCs) that have been developed by our group have been reviewed. PEFCs which can operate in temperature range from 100 to 200 °C are intensively studied because of some advantages such as reduction of CO poisoning of Pt catalyst and acceleration of electrode reactions. We showed that the fuel cells using the composite membranes prepared from phosphosilicate gel powder and polyimide precursor can operate in the temperature range from 30 to 180 °C. We also found that the inorganic-organic hybrid membranes with acid-base pairs from 3-aminopropyl triethoxy silane and H2SO4 or H3PO4 show high proton conductivity under dry atmosphere, and the membranes are thermally stable at intermediate temperatures. On the other hand, because the use of noble platinum is the serious problem for the commercialization of PEFCs and because oxidation reactions are usually faster than those of acid-type fuel cells, alkaline type fuel cells, in which a nonplatinum catalyst can be used, are attractive. Recently, we have proposed an alkaline-type direct ethanol fuel cell (DEFC) using a natural clay electrolyte with non-platinum catalysts. So-called hydrotalcite clay, Mg-Al layered double hydroxide intercalated with CO32- (Mg-Al CO32- LDH), has been proved to be a hydroxide ion conductor. An alkalinetype DEFC using Mg-Al CO32- LDH as the electrolyte and aqueous solution of ethanol and potassium hydroxide as a source of fuel exhibited excellent electrochemical performance.

Electrochemically reduced graphene-oxide supported bimetallic nanoparticles highly efficient for oxygen reduction reaction with excellent methanol tolerance

Science.gov (United States)

Yasmin, Sabina; Cho, Sung; Jeon, Seungwon

2018-03-01

We report a simple and facile method for the fabrication of bimetallic nanoparticles on electrochemically reduced graphene oxide (ErGO) for electrocatalytic oxygen reduction reaction (ORR) in alkaline media. First, reduced graphene oxide supported palladium and manganese oxide nanoparticle (rGO/Pd-Mn2O3) catalyst was synthesized via a simple chemical method at room temperature; then, it was electrochemically reduced for oxidation reduction reaction (ORR) in alkaline media. The chemical composition and morphological properties of ErGO/Pd-Mn2O3 was characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). The TEM images reveals that, nano-sized Pd and Mn2O3 particles were disperse on the ErGO sheet without aggregation. The as-prepared ErGO/Pd-Mn2O3 was employed for ORR in alkaline media which shows higher ORR activity with more positive onset and half-wave potential, respectively. Remarkably, ErGO/Pd-Mn2O3 reduced oxygen via four-electron transfer pathway with negligible amount of intermediate peroxide species (HO2-). Furthermore, the higher stability and excellent methanol tolerance of the ErGO/Pd-Mn2O3 compared to commercial Pt/C (20 wt%) catalyst, indicating its suitability for fuel cells.

Study of passive films formed on mild steel in alkaline media by the application of anodic potentials

Energy Technology Data Exchange (ETDEWEB)

Freire, L. [Universidade de Vigo, E.T.S.E.I., Campus Universitario, 36310 Vigo (Spain)], E-mail: lorenafp@uvigo.es; Novoa, X.R. [Universidade de Vigo, E.T.S.E.I., Campus Universitario, 36310 Vigo (Spain); Montemor, M.F. [ICEMS - Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049 - 001 Lisboa (Portugal); Carmezim, M.J. [ICEMS - Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049 - 001 Lisboa (Portugal); EST Setubal, DEM, Instituto Politecnico de Setubal, Campus IPS, 2910 Setubal (Portugal)

2009-04-15

In this paper, iron oxide thin layers formed on mild steel substrates in alkaline media by the application of different anodic potentials were studied in order to characterize their morphology, composition and electrochemical behaviour, in particular under conditions of cathodic protection. The surface composition was evaluated by X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). The morphology of the surface oxides was studied via Atomic Force Microscopy (AFM). The electrochemical behaviour of the surface oxides was studied using Electrochemical Impedance Spectroscopy (EIS). The results showed that the surface film is composed by Fe{sup 2+}oxides and Fe{sup 3+} oxides and/or hydroxides. The contribution of Fe{sup 2+} species vanishes when the potential of film formation increases in the passive domain. Two distinct phases were differentiated in the outer layers of the surface film, which proves that film growing is topotactic in nature.

Study of passive films formed on mild steel in alkaline media by the application of anodic potentials

International Nuclear Information System (INIS)

Freire, L.; Novoa, X.R.; Montemor, M.F.; Carmezim, M.J.

2009-01-01

In this paper, iron oxide thin layers formed on mild steel substrates in alkaline media by the application of different anodic potentials were studied in order to characterize their morphology, composition and electrochemical behaviour, in particular under conditions of cathodic protection. The surface composition was evaluated by X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). The morphology of the surface oxides was studied via Atomic Force Microscopy (AFM). The electrochemical behaviour of the surface oxides was studied using Electrochemical Impedance Spectroscopy (EIS). The results showed that the surface film is composed by Fe 2+ oxides and Fe 3+ oxides and/or hydroxides. The contribution of Fe 2+ species vanishes when the potential of film formation increases in the passive domain. Two distinct phases were differentiated in the outer layers of the surface film, which proves that film growing is topotactic in nature

Electrochemical behavior of cysteine at a CuGeO3 nanowires modified glassy carbon electrode

International Nuclear Information System (INIS)

Dong Yongping; Pei Lizhai; Chu Xiangfeng; Zhang Wangbing; Zhang Qianfeng

2010-01-01

A CuGeO 3 nanowire modified glassy carbon electrode was fabricated and characterized by scanning electron microscopy. The results of electrochemical impedance spectroscopy reveal that electron transfer through nanowire film is facile compared with that of bare glassy carbon electrode. The modified electrode exhibited a novel electrocatalytic behavior to the electrochemical reactions of L-cysteine in neutral solution, which was not reported previously. Two pairs of semi-reversible electrochemical peaks were observed and assigned to the processes of oxidation/reduction and adsorption/desorption of cysteine at the modified electrode, respectively. The electrochemical response of cysteine is poor in alkaline condition and is enhanced greatly in acidic solution, suggesting that hydrogen ions participate in the electrochemical oxidation process of cysteine. The intensities of two anodic peaks varied linearly with the concentration of cysteine in the range of 1 x 10 -6 to 1 x 10 -3 mol L -1 , which make it possible to sensitive detection of cysteine with the CuGeO 3 nanowire modified electrode. Furthermore, the modified electrode exhibited good reproducibility and stability.

Poly (pyrrole-co-aniline) hollow nanosphere supported Pd nanoflowers as high-performance catalyst for methanol electrooxidation in alkaline media

International Nuclear Information System (INIS)

Fard, Leyla Abolghasemi; Ojani, Reza; Raoof, Jahan Bakhsh; Zare, Ehsan Nazarzadeh; Lakouraj, Moslem Mansour

2017-01-01

In this work, first poly (pyrrole-co-aniline) (PPCA) hollow nanosphere (HN) as a catalyst support material is fabricated through in-situ emulsion polymerization. Then we reported a one-step and template-free approach to fabricate Pd NFs on a PPCA HN coated glassy carbon electrode by a facile electrochemical approach. Several techniques such as FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy) and EDS (energy dispersive spectroscopy) were utilized for the characterization of the synthesized materials. The catalytic performance of Pd NFs/PPCA HN catalyst is evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy toward methanol oxidation as a model reaction in alkaline media. The comparison of specific activities for Pd NFs/PPCA HN (1.79 mA cm"−"2), Pd NFs/PPy (1.28 mA cm"−"2), Pd NFs/PANI (0.93 mA cm"−"2) and Pd NFs (0.78 mA cm"−"2) shows that the PPCA supported Pd NFs with high surface area exhibits the excellent electrocatalytic activity than other electrodes for the electro-oxidation reaction in alkaline media. This might be due to the easier charge transfer at conductive copolymer interfaces, higher electrochemically accessible surface areas and electronic conductivity. This strategy provides a promising platform for direct methanol fuel cells. - Highlights: • Pd nanoflowers supported on poly (pyrrole-co-aniline) hollow nanosphere is prepared by a facile electrochemical approach. • The as-prepared nanocatalyst displays the enhanced electrocatalytic activity and stability for methanol oxidation. • The high performance is attributed to facile electron transfer on poly (pyrrole-co-aniline) hollow nanosphere substrate.

Porous Silicon–Carbon Composite Materials Engineered by Simultaneous Alkaline Etching for High-Capacity Lithium Storage Anodes

International Nuclear Information System (INIS)

Sohn, Myungbeom; Kim, Dae Sik; Park, Hyeong-Il; Kim, Jae-Hun; Kim, Hansu

2016-01-01

Highlights: • A porous Si–C anode is obtained by alkaline etching of a non-porous Si–C composite. • The pores in the carbon frame are created by simultaneous etching of Si and carbon. • The cycle life is greatly improved after the alkaline treatment. • The porous Si–C composite electrode shows high dimensional stability during cycling. - Abstract: Porous silicon–carbon (Si–C) composite materials have attracted a great deal of attention as high-performance anode materials for Li-ion batteries (LIBs), but their use suffers from the complex and limited synthetic routes for their preparation. Herein we demonstrate a scalable and nontoxic method to synthesize porous Si–C composite materials by means of simultaneous chemical etching of Si and carbon phases using alkaline solution. The resulting porous Si–C composite material showed greatly improved cycle performance, good rate capability, and high dimensional stability during cycling. Porous Si–C electrode showed an expansion of the height by about 22% after the first lithiation and only 16% after the first cycle. The material synthesis concept and scalable simultaneous etching approach presented here represent a means of improving the electrochemical properties of Si-based porous anode materials for use in commercial LIBs.

An efficient route for catalytic activity promotion via hybrid electro-depositional modification on commercial nickel foam for hydrogen evolution reaction in alkaline water electrolysis

Energy Technology Data Exchange (ETDEWEB)

Ma, Guanshui; He, Yongwei; Wang, Mei; Zhu, Fuchun; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Yingze West Road 79, Taiyuan 030024 (China); Wang, Xiaoguang, E-mail: wangxiaog1982@163.com [Research Institute of Surface Engineering, Taiyuan University of Technology, Yingze West Road 79, Taiyuan 030024 (China); International Iberian Nanotechnology Laboratory (INL), 4715-330 Braga (Portugal)

2014-09-15

Highlights: • Mono-Cu surface modification depress the HER activity of Ni-foam. • Hybrid Ni-foam/Cu0.01/Co0.05 exhibits superior HER performance. • Layer-by-layer structure may contribute to a synergistic promoting effect. - Abstract: In this paper, the single- and hybrid-layered Cu, Ni and Co thin films were electrochemically deposited onto the three-dimensional nickel foam as composite cathode catalyst for hydrogen evolution reaction in alkaline water electrolysis. The morphology, structure and chemical composition of the electrodeposited composite catalysts were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Electrochemical measurement depicted that, for the case of the monometallic layered samples, the general activity for hydrogen evolution reaction followed the sequence: Ni-foam/Ni > Ni-foam/Co > bare Ni-foam > Ni-foam/Cu. It is noteworthy that, the hybrid-layered Ni-foam/Cu0.01/Co0.05 exhibited the highest catalytic activity towards hydrogen evolution reaction with the current density as high as 2.82 times that of the bare Ni-foam. Moreover, both excellent electrochemical and physical stabilities can also be acquired on the Ni-foam/Cu0.01/Co0.05, making this hybrid-layered composite structure as a promising HER electro-catalyst.

Kinetics and mechanism of permanganate oxidation of iota- and lambda-carrageenan polysaccharides as sulfated carbohydrates in acid perchlorate solutions.

Science.gov (United States)

Hassan, Refat M; Fawzy, Ahmed; Ahmed, Gamal A; Zaafarany, Ishaq A; Asghar, Basim H; Takagi, Hideo D; Ikeda, Yasuhisa

2011-10-18

The kinetics of oxidation of iota- and lambda-carrageenan as sulfated carbohydrates by permanganate ion in aqueous perchlorate solutions at a constant ionic strength of 2.0 mol dm(-3) have been investigated spectrophotometrically. The pseudo-first-order plots were found to be of inverted S-shape throughout the entire courses of reactions. The initial rates were found to be relatively slow in the early stages, followed by an increase in the oxidation rates over longer time periods. The experimental observations showed first-order dependences in permanganate and fractional first-order kinetics with respect to both carrageenans concentration for both the induction and autoacceleration periods. The results obtained at various hydrogen ion concentrations showed that the oxidation processes in these redox systems are acid-catalyzed throughout the two stages of oxidation reactions. The added salts lead to the prediction that Mn(III) is the reactive species throughout the autoacceleration periods. Kinetic evidence for the formation of 1:1 intermediate complexes was revealed. The kinetic parameters have been evaluated and tentative reaction mechanisms in good agreement with the kinetic results are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

Mineralogical, petrological and geochemical aspects of alkaline and alkaline-carbonatite associations from Brazil

Science.gov (United States)

Morbidelli, L.; Gomes, C. B.; Beccaluva, L.; Brotzu, P.; Conte, A. M.; Ruberti, E.; Traversa, G.

1995-12-01

A general description of Mesozoic and Tertiary (Fortaleza) Brazilian alkaline and alkaline-carbonatite districts is presented with reference to mineralogy, petrology, geochemistry and geochronology. It mainly refers to scientific results obtained during the last decade by an Italo-Brazilian research team. Alkaline occurrences are distributed across Brazilian territory from the southern (Piratini, Rio Grande do Sul State) to the northeastern (Fortaleza, Ceará State) regions and are mainly concentrated along the borders of the Paraná Basin generally coinciding with important tectonic lineaments. The most noteworthy characteristics of these alkaline and alkaline-carbonatite suites are: (i) prevalence of intrusive forms; (ii) abundance of cumulate assemblages (minor dunites, frequent clinopyroxenites and members of the ijolite series) and (iii) abundance of evolved rock-types. Many data demonstrate that crystal fractionation was the main process responsible for magma evolution of all Brazilian alkaline rocks. A hypothesis is proposed for the genesis of carbonatite liquids by immiscibility processes. The incidence of REE and trace elements for different major groups of lithotypes, belonging both to carbonatite-bearing and carbonatite-free districts, are documented. Sr and preliminary Nd isotopic data are indicative of a mantle origin for the least evolved magmas of all the studied occurrences. Mantle source material and melting models for the generation of the Brazilian alkaline magma types are also discussed.

Alkaline solution/binder ratio as a determining factor in the alkaline activation of aluminosilicates

Energy Technology Data Exchange (ETDEWEB)

Ruiz-Santaquiteria, C., E-mail: ruiz.cs@ietcc.csic.es [Eduardo Torroja Institute (CSIC), c/Serrano Galvache, n Degree-Sign 4, 28033 Madrid (Spain); Skibsted, J. [Instrument Centre for Solid-State NMR Spectroscopy, Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Fernandez-Jimenez, A.; Palomo, A. [Eduardo Torroja Institute (CSIC), c/Serrano Galvache, n Degree-Sign 4, 28033 Madrid (Spain)

2012-09-15

This study investigates the effect of the alkaline solution/binder (S/B) ratio on the composition and nanostructure of the reaction products generated in the alkaline activation of aluminosilicates. The experiments used two mixtures of fly ash and dehydroxylated white clay and for each of these, varying proportions of the solution components. The alkali activator was an 8 M NaOH solution (with and without sodium silicate) used at three S/B ratios: 0.50, 0.75 and 1.25. The {sup 29}Si, {sup 27}Al MAS NMR and XRD characterisation of the reaction products reveal that for ratios nearest the value delivering suitable paste workability, the reaction-product composition and structure depend primarily on the nature and composition of the starting materials and the alkaline activator used. However, when an excess alkaline activator is present in the system, the reaction products tend to exhibit SiO{sub 2}/Al{sub 2}O{sub 3} ratios of approximately 1, irrespective of the composition of the starting binder or the alkaline activator.

Permanganate-based synthesis of manganese oxide nanoparticles in ferritin

Science.gov (United States)

Olsen, Cameron R.; Smith, Trevor J.; Embley, Jacob S.; Maxfield, Jake H.; Hansen, Kameron R.; Peterson, J. Ryan; Henrichsen, Andrew M.; Erickson, Stephen D.; Buck, David C.; Colton, John S.; Watt, Richard K.

2017-05-01

This paper investigates the comproportionation reaction of MnII with {{{{MnO}}}4}- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that {{{{MnO}}}4}- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

Permanganate Fixation of Plant Cells

Science.gov (United States)

Mollenhauer, Hilton H.

1959-01-01

In an evaluation of procedures explored to circumvent some of the problems of osmium tetroxide-fixation and methacrylate embedding of plant materials, excised segments of root tips of Zea mays were fixed for electron microscopy in potassium permanganate in the following treatment variations: unbuffered and veronal-acetate buffered solutions of 0.6, 2.0, and 5.0 per cent KMnO4 at pH 5.0, 6.0, 6.7, and 7.5, and temperatures of 2–4°C. and 22°C. After fixation the segments were dehydrated, embedded in epoxy resin, sectioned, and observed or photographed. The cells of the central region of the rootcap are described. The fixation procedures employing unbuffered solutions containing 2.0 to 5.0 per cent KMnO4 at a temperature of 22°C. gave particularly good preservation of cell structure and all membrane systems. Similar results were obtained using a solution containing 2.0 per cent KMnO4, buffered with veronal-acetate to pH 6.0, and a fixation time of 2 hours at 22°C. The fixation procedure utilizing veronal-acetate buffered, 0.6 per cent KMnO4 at 2–4°C. and pH 6.7 also gave relatively good preservation of most cellular constituents. However, preservation of the plasma membrane was not so good, nor was the intensity of staining so great, as that with the group of fixatives containing greater concentrations of KMnO4. The other fixation procedures did not give satisfactory preservation of fine structure. A comparison is made of cell structures as fixed in KMnO4 or OsO4. PMID:14423414

Electro-oxidation of methanol on gold in alkaline media: Adsorption characteristics of reaction intermediates studied using time resolved electro-chemical impedance and surface plasmon resonance techniques

Science.gov (United States)

Assiongbon, K. A.; Roy, D.

2005-12-01

Electro-catalytic oxidation of methanol is the anode reaction in direct methanol fuel cells. We have studied the adsorption characteristics of the intermediate reactants of this multistep reaction on a gold film electrode in alkaline solutions by combining surface plasmon resonance (SPR) measurements with Fourier transform electro-chemical impedance spectroscopy (FT-EIS). Methanol oxidation in this system shows no significant effects of "site poisoning" by chemisorbed CO. Our results suggest that OH - chemisorbed onto Au acts as a stabilizing agent for the surface species of electro-active methanol. Double layer charging/discharging and adsorption/desorption of OH - show more pronounced effects than adsorption/oxidation of methanol in controlling the surface charge density of the Au substrate. These effects are manifested in both the EIS and the SPR data, and serve as key indicators of the surface reaction kinetics. The data presented here describe the important role of adsorbed OH - in electro-catalysis of methanol on Au, and demonstrate how SPR and FT-EIS can be combined for quantitative probing of catalytically active metal-solution interfaces.

Alkaline sulfide pretreatment of an antimonial refractory Au-Ag ore for improved cyanidation

Science.gov (United States)

Alp, Ibrahim; Celep, Oktay; Deveci, Haci

2010-11-01

This paper presents the alkaline sulfide pretreatment of an antimonial refractory gold and silver ore. In the ore, gold occurs mainly as gold-silver alloys and as associated with quartz and framboidal pyrite grains, and, to a small extent, as the inclusions within antimonial sulfides. Silver is present extensively as antimonial sulfides such as andorite. Alkaline sulfide pretreatment was shown to allow the decomposition of the antimonial sulfide minerals (up to 98% Sb removal) and to remarkably improve the amenability of gold (e.g., from leaching. An increase in reagent concentration (1-4 mol/L Na2S or NaOH) and temperature (20-80°C), and a decrease in particle size seem to produce an enhancing effect on metal extraction. These findings suggest that alkaline sulfide leaching can be suitably used as a chemical pretreatment method prior to the conventional cyanidation for antimonial refractory gold and silver ores.

The construction of a magnetite electrode for measurement of the electrochemical property

Energy Technology Data Exchange (ETDEWEB)

Kim, Myongjin; Kim, Hong Pyo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Flow accelerated corrosion (FAC) causes severe damage to secondary piping systems. An accident from FAC occurred at the Oyster Creek nuclear power plant (NPP) in 1978. Other NPPs such as Surry 2 and Mihama 3 have also experienced an FAC that induced damage to the carbon steel piping. FAC is influenced by many factors such as the water chemistry (temperature, pH, dissolved oxygen (D. O.) in a solution, and etc.), chemical composition of carbon steel, and fluid dynamics. Magnetite is formed at the inner surface of carbon steel, and protects the integrity of pipes from damage. The magnetite has a stable state at each equilibrium condition, so that it can be dissolved into the fluid under conditions that satisfy the equilibrium state. The iron solubility can be calculated by considering the reaction equilibrium constants for prediction of the change in the magnetite layer. On the other hand, it is necessary to measure the experimental solubility to compare the theoretical data and the experimental data. In addition, the solubility of magnetite can be predicted by measuring the electrochemical experiments. However, there are few studies related to the electrochemical property of magnetite owing to the difficulty of the electrode fabrication. In the present work, a magnetite electrode was prepared using a dipping method, and the electrochemical property of the magnetite electrode was measured in an alkaline solution.

Evaluation of an alkaline fuel cell system as a micro-CHP

International Nuclear Information System (INIS)

Verhaert, Ivan; Mulder, Grietus; De Paepe, Michel

2016-01-01

Highlights: • Sensitivity analysis on system configuration of the AFC as a micro-CHP. • Flow rate in the secondary heating circuit can be used to control water management. • Part load behavior of fuel cells is compared to other micro-CHP technologies. • For future energy demand in buildings fuel cells have the best performance. - Abstract: Micro-cogeneration is an emerging technology to reduce the non-renewable energy demand in buildings and reduce peak load in the grid. Fuel cell based cogeneration (CHP) has interesting prospects for building applications, even at relatively low heat demand. This is due to their partial load behavior which is completely different, compared to other micro-CHP technologies. Within the fuel cell technologies suitable for small scale CHP or micro-CHP, the existing configuration of an alkaline fuel cell system is analyzed. This analysis is based on validated models and offers a control strategy to optimize both water management and energy performance of the alkaline fuel cell system. Finally, the model of the alkaline fuel cell system with optimized control strategy is used to compare its part load behavior to other micro-CHP technologies.

Development of the electrochemically regenerable carbon dioxide absorber for portable life support system application

Science.gov (United States)

Woods, R. R.; Heppner, D. B.; Marshall, R. D.; Quattrone, P. D.

1979-01-01

As the length of manned space missions increase, more ambitious extravehicular activities (EVAs) are required. For the projected longer mission the use of expendables in the portable life support system (PLSS) will become prohibited due to high launch weight and volume requirements. Therefore, the development of a regenerable CO2 absorber for the PLSS application is highly desirable. The paper discusses the concept, regeneration mechanism, performance, system design, and absorption/regeneration cycle testing of a most promising concept known as ERCA (Electrochemically Regenerable CO2 Absorber). This concept is based on absorbing CO2 into an alkaline absorbent similar to LiOH. The absorbent is an aqueous solution supported in a porous matrix which can be electrochemically regenerated on board the primary space vehicle. With the metabolic CO2 recovery the ERCA concept results in a totally regenerable CO2 scrubber. The ERCA test hardware has passed 200 absorption/regeneration cycles without performance degradation.

Passive behavior of magnesium alloys (Mg-Zr) containing rare-earth elements in alkaline media

International Nuclear Information System (INIS)

Pinto, R.; Ferreira, M.G.S.; Carmezim, M.J.; Montemor, M.F.

2010-01-01

The passive behavior of magnesium alloys ZK31, EZ33 and WE54 was studied in alkaline media (NaOH - pH 13) in the presence and absence of chloride ions. The electrochemical properties were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and capacitance measurements. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed for the study of the chemical composition and surface morphology of the surface films, respectively. The electrochemical impedance results revealed that the film formed on the surface of the three alloys is characterized by an increasing resistance, which stabilized with time. In the absence of chloride the film resistance was identical for all the three alloys. However, in the presence of chloride, the resistance of the film formed on the EZ33 alloy dropped nearly one order of magnitude comparatively to the other alloys. Generally, in the presence of chloride there was a decrease of the conductive character of the film. The films are homogeneous and, according to the XPS results, the outer layer seemed mainly composed of Mg(OH) 2 and the internal layer composed of MgO, independently of the presence of chloride. The AFM study revealed that the presence of chloride affected film morphology, namely nano-crystallites dimensions and aggregates size that increased.

Potassium permanganate effects on the quality and post-harvest conservation of sapodilla (Manilkara zapota (L. P.Royen fruits under modified atmosphere

Directory of Open Access Journals (Sweden)

Wallace Edelky de Souza Freitas

2017-07-01

Full Text Available Sapodilla (Manilkara zapota (L. P. Royen is a climacteric fruit, very perishable, with high metabolic activity, rapid ripening and reduced storage time at room temperature, thus making difficult its commercialization. However, this research aimed to evaluate the effect of potassium permanganate (KMnO4 on the quality and post-harvest conservation of sapodilla fruit under modified atmosphere at room temperature. The sapodilla fruits were harvested when they reached physiological maturity and then accommodated in Styrofoam trays with PVC film coating. Within each package, KMnO4 were placed at different concentrations (0, 0.250, 0.375, and 0.500 g of KMnO4 per kg of fruit, respectively, impregnated in vermiculite. In addition, were kept in storage at room temperature (25 ± 1 °C and 54 ± 5% RU for fifteen days, with fruit quality analysis every five days. The potassium permanganate doses influenced the sapodilla fruit quality, wherein the concentration of 0.375 g of KMnO4 per kg of fruit was the most efficient, retarding the loss of firmness and vitamin C degradation of sapodilla fruits throughout five days storage under modified atmosphere at room temperature. The sapodilla fruit postharvest life stored under modified atmosphere with potassium permanganate 25 ± 1 °C and 54 ± 5% RU, is ten days.

A new way for preparing superconducting materials: the electrochemical oxidation of La2CuO4

International Nuclear Information System (INIS)

Wattiaux, A.; Park, J.C.; Grenier, J.C.; Pouchard, M.

1990-01-01

The electrochemical oxidation in alkaline medium is described as a new way for preparing superconducting oxides at room temperature. The application of this method to La 2 CuO 4 gave rise to a metallic material with a superconducting behaviour below 39 K and whose physical and chemical features appear as quite promising [fr

High Temperature and Pressure Alkaline Electrochemical Reactor for Conversion of Power to Chemicals

DEFF Research Database (Denmark)

Chatzichristodoulou, Christodoulos

2016-01-01

forces. Raising the operating temperature offers a means to boost performance, as both ionic transport and reaction kinetics are exponentially activated with temperature. Indeed, we have demonstrated alkaline electrolysis cells operating at 200-250 °C and 20-50 bar at very high efficiencies and power...... been established enabling experiments with gaseous or liquids reactants/products at cell sizes of up to 25 cm2. Efforts are currently directed towards the investigation of the intrinsic activity of mixed oxides for the oxygen evolution reaction at elevated temperatures and pressures...

The influence of current collector corrosion on the performance of electrochemical capacitors

Science.gov (United States)

Wojciechowski, Jarosław; Kolanowski, Łukasz; Bund, Andreas; Lota, Grzegorz

2017-11-01

This paper discusses the effect of current collector (stainless steel 316L) corrosion on the performance of electrochemical capacitors operated in aqueous electrolytes. This topic seems to be often neglected in scientific research. The studied electrolytes were 1 M H2SO4, 1 M KI, 1 M Na2SO4, 1 M KOH and 6 M KOH. The corrosion process was investigated by means of selected direct and alternating current techniques. The surface of the current collectors as well as the corrosion products were characterised using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and atomic force microscopy. Stainless steel 316L in alkaline solutions is characterised by the lowest values of corrosion potentials whereas the potentials in acidic media become the most noble. Our studies show that corrosion potentials increase with decreasing pH value. This phenomenon can be explained with the formation of passive oxide films on the stainless steel current collectors. The passive oxide films are usually thicker and more porous in alkaline solutions than that in the other electrolytes. The processes occurring at the electrode/electrolyte interfaces strongly influence the working parameters of electrochemical capacitors such as voltage, working potentials of single electrodes, self-discharge as well as the internal resistance and cycling stability.

On the Electrochemical Behavior of PVD Ti-Coated AISI 304 Stainless Steel in Borate Buffer Solution

Science.gov (United States)

Fattah-alhosseini, Arash; Elmkhah, Hassan; Attarzadeh, Farid Reza

2017-04-01

This work aims at studying the electrochemical behavior of annealed pure titanium (Ti) and nano-structured (NS) Ti coating in borate buffer solutions. Cathodic arc evaporation was successfully applied to deposit NS Ti coating. Samples were characterized by means of scanning electron microscope and x-ray diffraction. Potentiodynamic polarization tests, electrochemical impedance spectroscopy, and Mott-Schottky analysis were employed to discuss the electrochemical behavior of samples thoroughly. Electrochemical measurements showed that the deposited NS Ti coating offers a superior passivity in borate buffer solutions of pH 9.0 and 9.5. Mott-Schottky analysis revealed that all passive films are of n-type semiconducting nature in these alkaline solutions and the deposition process did not alter the semiconducting type of passive films formed on samples. Additionally, this analysis showed that the NS Ti coating possessed lower levels of donor densities. Finally, all electrochemical tests showed that passive behavior of the NS Ti samples was superior, mainly due to the formation of thicker and less defective passive films.

Microcystis aeruginosa-laden water treatment using enhanced coagulation by persulfate/Fe(II), ozone and permanganate: Comparison of the simultaneous and successive oxidant dosing strategy.

Science.gov (United States)

Liu, Bin; Qu, Fangshu; Chen, Wei; Liang, Heng; Wang, Tianyu; Cheng, Xiaoxiang; Yu, Huarong; Li, Guibai; Van der Bruggen, Bart

2017-11-15

In this study, the application of enhanced coagulation with persulfate/Fe(II), permanganate and ozone for Microcystis-laden water treatment was investigated. Two oxidant dosage strategies were compared in terms of the organic removal performance: a simultaneous dosing strategy (SiDS) and a successive dosing strategy (SuDS). To optimize the oxidant species, oxidant doses and oxidant dosage strategy, the zeta potential, floc size and dimension fraction, potassium release and organic removal efficiency during the coagulation of algae-laden water were systematically investigated and comprehensively discussed. Ozonation causes most severe cell lysis and reduces organic removal efficiency because it releases intracellular organics. Moreover, ozonation can cause the release of odor compounds such as 2-methylisoborneol (2-MIB) and geosmin (GSM). With increasing doses, the performance of pollutant removal by coagulation enhanced by persulfate/Fe(II) or permanganate did not noticeably improve, which suggests that a low dosage of persulfate/Fe(II) and permanganate is the optimal strategy to enhance coagulation of Microcystis-laden water. The SiDS performs better than the SuDS because more Microcystis cell lysis occurs and less DOC is removed when oxidants are added before the coagulants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Method of constructing an improved electrochemical cell

Science.gov (United States)

Grimes, Patrick G.; Einstein, Harry

1984-10-09

An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

Facile chemical synthesis of nanoporous layered δ-MnO{sub 2} thin film for high-performance flexible electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Hu, Yu; Wang, Jun; Jiang, Xionghua; Zheng, Yanfeng [The Key Laboratory of Low-Carbon Chemistry and Energy Conservation of Guangdong Province, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Chen, Zhenxing, E-mail: chenzx65@mail.sysu.edu.cn [The Key Laboratory of Low-Carbon Chemistry and Energy Conservation of Guangdong Province, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

2013-04-15

Layered δ-MnO{sub 2} thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15 °C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of δ-MnO{sub 2}. Electrochemical data demonstrate that the δ-MnO{sub 2} thin film electrodes can deliver a high special capacitance of 447 F/g at 2 mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10 mV/s in 0.5 M Na{sub 2}SO{sub 4}. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between −2.5 cm{sup −1} (tension) and 2.5 cm{sup −1} (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5 cm{sup −1} under compressive strain, or 1.2% at a curvature of −2.5 cm{sup −1} under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the δ-MnO{sub 2} thin film electrodes.

Capsid protein oxidation in feline calicivirus using an electrochemical inactivation treatment

Energy Technology Data Exchange (ETDEWEB)

Shionoiri, Nozomi; Nogariya, Osamu; Tanaka, Masayoshi; Matsunaga, Tadashi; Tanaka, Tsuyoshi, E-mail: tsuyo@cc.tuat.ac.jp

2015-02-11

Highlights: • Feline calicivirus was inactivated electrochemically by a factor of >5 log. • The electrochemical treatment was performed at 0.9 V (vs. Ag/AgCl) for 15 min. • Electrochemical treatment caused oxidation of viral proteins. • Oxidation of viral proteins can lead to loss of viral structural integrity. - Abstract: Pathogenic viral infections are an international public health concern, and viral disinfection has received increasing attention. Electrochemical treatment has been used for treatment of water contaminated by bacteria for several decades, and although in recent years several reports have investigated viral inactivation kinetics, the mode of action of viral inactivation by electrochemical treatment remains unclear. Here, we demonstrated the inactivation of feline calicivirus (FCV), a surrogate for human noroviruses, by electrochemical treatment in a developed flow-cell equipped with a screen-printed electrode. The viral infectivity titer was reduced by over 5 orders of magnitude after 15 min of treatment at 0.9 V vs. Ag/AgCl. Proteomic study of electrochemically inactivated virus revealed oxidation of peptides located in the viral particles; oxidation was not observed in the non-treated sample. Furthermore, transmission electron microscopy revealed that viral particles in the treated sample had irregular structures. These results suggest that electrochemical treatment inactivates FCV via oxidation of peptides in the structural region, causing structural deformation of virus particles. This first report of viral protein damage through electrochemical treatment will contribute to broadening the understanding of viral inactivation mechanisms.

Enzyme-linked electrochemical DNA ligation assay using magnetic beads.

Science.gov (United States)

Stejskalová, Eva; Horáková, Petra; Vacek, Jan; Bowater, Richard P; Fojta, Miroslav

2014-07-01

DNA ligases are essential enzymes in all cells and have been proposed as targets for novel antibiotics. Efficient DNA ligase activity assays are thus required for applications in biomedical research. Here we present an enzyme-linked electrochemical assay based on two terminally tagged probes forming a nicked junction upon hybridization with a template DNA. Nicked DNA bearing a 5' biotin tag is immobilized on the surface of streptavidin-coated magnetic beads, and ligated product is detected via a 3' digoxigenin tag recognized by monoclonal antibody-alkaline phosphatase conjugate. Enzymatic conversion of napht-1-yl phosphate to napht-1-ol enables sensitive detection of the voltammetric signal on a pyrolytic graphite electrode. The technique was tested under optimal conditions and various situations limiting or precluding the ligation reaction (such as DNA substrates lacking 5'-phosphate or containing a base mismatch at the nick junction, or application of incompatible cofactor), and utilized for the analysis of the nick-joining activity of a range of recombinant Escherichia coli DNA ligase constructs. The novel technique provides a fast, versatile, specific, and sensitive electrochemical assay of DNA ligase activity.

Facile synthesis of MnO{sub 2}/CNT nanocomposite and its electrochemical performance for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Wang Hongjuan, E-mail: cehjwang@scut.edu.cn [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China); Peng Cheng [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China); Peng Feng, E-mail: cefpeng@scut.edu.cn [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China); Yu Hao; Yang Jian [School of Chemistry and Chemcial Engineering, South China University of Technology, Guangzhou, 510640 (China)

2011-08-25

Highlights: > MnO{sub 2}/CNTs are prepared by direct redox reaction between KMnO{sub 4} and carbon nanotubes. > This preparation method is a simple and green without any other additives. > MnO{sub 2}/CNTs show specific capacitance of 162.2 F g{sup -1} at the current density of 0.2 A g{sup -1}. > MnO{sub 2}/CNTs exhibit excellent charge-discharge property. - Abstract: A nanocomposite of manganese dioxide coated on the carbon nanotubes (MnO{sub 2}/CNTs) was synthesized by a facile direct redox reaction between potassium permanganate and carbon nanotubes without any other oxidant or reductant addition. The morphology, microstructure and crystalline form of this MnO{sub 2}/CNT nanocomposite were characterized by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties are characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD). The results show that the facile prepared MnO{sub 2}/CNTs nanocomposite shows specific capacitance of 162.2 F g{sup -1} at the current density of 0.2 A g{sup -1} and excellent charge/discharge property with 90% of its specific capacitance kept after 2000 cycles at the current density of 5 A g{sup -1}.

Electrochemical characterization of calcium cobaltite based porous electrodes

International Nuclear Information System (INIS)

Fulgencio, E.B.G.A.; Vasconcelos, K.; Silva, R.M.; Melo, P.; Caetano, A.A.; Campos, L.F.A.; Dutra, R.P.S.; Macedo, D.A.

2016-01-01

Materials based on alkali metal oxides and alkaline earth metal have shown high technological interest in recent years. Among these materials, calcium and cobalt oxide composition Ca_3Co_4O_9 (C349) has emerged as thermoelectric material and, more recently, as cathode for solid oxide fuel cell (SOFC). In this study, C349 powder was obtained by solid state reaction of a mixture containing cobalt oxide and calcium carbonate from shellfish shells (CaCO_3 ∼ 98%), previously calcined at 550° C. Symmetrical cells (cathode / substrate / cathode) were prepared by screen printing of C349 electrodes in gadolinium-doped ceria substrates. The characterization by electrochemical impedance spectroscopy revealed that the C349 obtained in this work has an area specific resistance compatible with electrodes obtained by chemical routes (from literature). (author)

Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

Science.gov (United States)

Gobal, Fereydoon; Faraji, Masoud

2014-12-01

Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc-cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 1 M NaOH solution. The electrochemical data demonstrated that the electrodes display good capacitive behavior with a specific capacitance of 430 F g-1 at a current density of 1.0 A g-1 and specific capacitance retention of ca. 80 % after 10 days of being used in electrochemical experiments, indicating to be promising electroactive materials for supercapacitors. Furthermore, in comparison with electrodes prepared by simple cathodic deposition of cobalt onto TiO2 nanotubes(without dealloying procedure), the impedance studies showed improved performances likely due to nanoporous/cracked structures of electrodes fabricated by dealloying of zinc, which provide fast ion and electron transfer routes and large reaction surface area with the ensued fast reaction kinetics.

The kinetics and mechanism of methanol oxidation on Pt and PtRu catalysts in alkaline and acid media

Directory of Open Access Journals (Sweden)

JELENA LOVIC

2007-07-01

Full Text Available The kinetic of methanol electrochemical oxidation for a series of platinum and platinum–ruthenium catalysts was investigated. A correlation between the beginning of OHad adsorption and methanol oxidation was demonstarated on Pt single crystals and Pt nanocatalyst. The activity of the nano-structured Pt catalyst was compared with single crystal platinum electrodes assuming the Kinoshita model of nanoparticles. The ruthenium-containing catalysts shifted the onset of methanol oxidation to more negative potentials. The effect was more pronounced in acid than in alkaline media. Based on the established diagnostic criteria, the reaction between COad and OHad species according to the Langmuir–Hinshelwood mechanism was proposed as the rate determining step in alkaline and acid media on Pt and PtRu catalysts.

Electrochemical Studies for Cation Recognition with Diazo-Coupled Calix[4]arenes

Directory of Open Access Journals (Sweden)

Bongsu Kim

2015-01-01

Full Text Available The electrochemical properties of diazophenylcalix[4]arenes bearing ortho-carboxyl group (o-CAC and ortho-ester group (o-EAC, respectively, in the presence of various metal ions were investigated by voltammetry in CH3CN. o-CAC and o-EAC showed voltammetric changes toward divalent metal ions and no significant changes with monovalent alkali metal ions. However, o-CAC preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in voltammetric signals are observed in o-EAC with alkaline earth metal ions. o-EAC only binds with other transition metal ions. This can be explained on metal ion complexation-induced release of proton from the azophenol to the quinone-hydrazone tautomer followed by internal complexation of the metal ion with aid of nitrogen atoms and ortho-carbonyl groups in the diazophenylazocalix[4]arenes.

Electrochemical treatment of graphite

Energy Technology Data Exchange (ETDEWEB)

Podlovilin, V.I.; Egorov, I.M.; Zhernovoj, A.I.

1983-01-01

In the course of investigating various modes of electrochemical treatment (ECT) it has been found that graphite anode treatment begins under the ''glow mode''. A behaviour of some marks of graphite with the purpose of ECT technique development in different electrolytes has been tested. Electrolytes have been chosen of three types: highly alkaline (pH 13-14), neutral (pH-Z) and highly acidic (pH 1-2). For the first time parallel to mechanical electroerosion treatment, ECT of graphite and carbon graphite materials previously considered chemically neutral is proposed. ECT of carbon graphite materials has a number of advantages as compared with electroerrosion and mechanical ones with respect to the treatment rate and purity (ronghness) of the surface. A small quantity of sludge (6-8%) under ECT is in highly alkali electrolytes.

Kinetic, mechanistic, and spectroscopic studies of permanganate oxidation of azinylformamidines in acidic medium, with autocatalytic behavior of manganese(II

Directory of Open Access Journals (Sweden)

Basim H. Asghar

2016-09-01

Full Text Available The kinetics of permanganate oxidation of two substituted azinylformamidines (Azn-Fs, namely N,N-dimethyl-N′-(pyridin-2-ylformamidine (Py and N,N-dimethyl-N′-(pyrimidin-2-ylformamidine (Pym, in sulfuric acid were investigated using conventional spectrophotometry. Kinetic evidence for the formation of 1:1 intermediate complexes between the oxidant and substrates was obtained. The reactions of both substrates with permanganate showed similar kinetics, i.e. first order in [MnO4−]0 and fractional-first-order with respect to both [Azn-F]0 and [H+]. The initial product, Mn2+, was found to autocatalyze the oxidation process. Changes in the ionic strength and dielectric constant of the medium had no significant effect on the rate. The final oxidation products of Py and Pym were identified as 2-aminopyridine and 2-aminopyrimidine, respectively, in addition to dimethylamine and carbon dioxide. A plausible reaction mechanism is suggested and the reaction constants involved in the mechanism were evaluated.

High-pressure water electrolysis: Electrochemical mitigation of product gas crossover

International Nuclear Information System (INIS)

Schalenbach, Maximilian; Stolten, Detlef

2015-01-01

Highlights: • New technique to reduce gas crossover during water electrolysis • Increase of the efficiency of pressurized water electrolysis • Prevention of safety hazards due to explosive gas mixtures caused by crossover • Experimental realization for a polymer electrolyte membrane electrolyzer • Discussion of electrochemical crossover mitigation for alkaline water electrolysis - Abstract: Hydrogen produced by water electrolysis can be used as an energy carrier storing electricity generated from renewables. During water electrolysis hydrogen can be evolved under pressure at isothermal conditions, enabling highly efficient compression. However, the permeation of hydrogen through the electrolyte increases with operating pressure and leads to efficiency loss and safety hazards. In this study, we report on an innovative concept, where the hydrogen crossover is electrochemically mitigated by an additional electrode between the anode and the cathode of the electrolysis cell. Experimentally, the technique was applied to a proton exchange membrane water electrolyzer operated at a hydrogen pressure that was fifty times larger than the oxygen pressure. Therewith, the hydrogen crossover was reduced and the current efficiency during partial load operation was increased. The concept is also discussed for water electrolysis that is operated at balanced pressures, where the crossover of hydrogen and oxygen is mitigated using two additional electrodes

Novel palladium-lead (Pd-Pb/C) bimetallic catalysts for electrooxidation of ethanol in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Wang, Yi; Nguyen, Truong Son; Wang, Xin [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Xuewei [School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798 (Singapore)

2010-05-01

Carbon-supported bimetallic palladium-lead (Pd-Pb/C) catalysts with different amounts of lead are prepared using a co-reduction method. The catalysts are characterized by various techniques, which reveal the formation of an alloy nanoparticle structure. The electrochemical activities of the catalysts towards ethanol oxidation in alkaline media are examined by cyclic voltammetry, linear sweep voltammetry and chronoamperometry methods. The results show that the Pd-Pb(4:1)/C catalyst exhibits a better catalytic activity than the Pd/C catalyst. From carbon monoxide (CO) stripping results, the addition of lead also facilitates the oxidative removal of adsorbed CO. The promoting effect of lead is explained by a bi-functional mechanism and d-band theory. (author)

Synthesis and crystal structure of the cesium silver permanganate Cs{sub 3}Ag[MnO{sub 4}]{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Bauchert, Joerg M.; Henning, Harald; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany)

2012-09-15

After successful syntheses and structural refinements of the already known permanganates of cesium (Cs[MnO{sub 4}]) and silver (Ag[MnO{sub 4}]) we started to blend aqueous solutions of both components in various molar ratios. From crystallization experiments of these mixtures only three species of crystals with different chemical compositions were obtained: tricesium monosilver tetrakispermanganate (Cs{sub 3}Ag[MnO{sub 4}]{sub 4}) and, depending upon the respective ratio, either additional silver permanganate or surplus cesium permanganate, namely. The new title compound crystallizes in the orthorhombic space group Pnnm (no. 58) with two formula units per unit cell and cell dimensions of a = 764.53(4), b = 1883.57(9) and c = 584.34(3) pm. The crystal structure of Cs{sub 3}Ag[MnO{sub 4}]{sub 4} consists of two crystallographically distinguishable cesium cations. (Cs1){sup +} is surrounded by fourteen oxygen atoms constructing a slightly distorted bicapped hexagonal prism. These polyhedra are connected through edge-sharing with two other polyhedra of this kind to form chains along [001]. The chains are linked to each other via sixfold coordinated Ag{sup +} cations (d(Ag-O) = 238-246 pm), arranged in such a manner that they link three oxygen atoms of two cesium polyhedra, leading to a two-dimensional layer spreading out parallel to the (001) plane. Together with the two crystallographically different tetrahedral oxomanganate(VII) anions [MnO{sub 4}]{sup -} (d(Mn-O) = 161-162 pm) the other kind of cesium cations ((Cs2){sup +} with CN = 13) finally connect these layers three-dimensionally. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Rapid extraction and quantitative detection of the herbicide diuron in surface water by a hapten-functionalized carbon nanotubes based electrochemical analyzer.

Science.gov (United States)

Sharma, Priyanka; Bhalla, Vijayender; Tuteja, Satish; Kukkar, Manil; Suri, C Raman

2012-05-21

A solid phase extraction micro-cartridge containing a non-polar polystyrene absorbent matrix was coupled with an electrochemical immunoassay analyzer (EIA) and used for the ultra-sensitive detection of the phenyl urea herbicide diuron in real samples. The EIA was fabricated by using carboxylated carbon nanotubes (CNTs) functionalized with a hapten molecule (an amine functionalized diuron derivative). Screen printed electrodes (SPE) were modified with these haptenized CNTs and specific in-house generated anti diuron antibodies were used for bio-interface development. The immunodetection was realized in a competitive electrochemical immunoassay format using alkaline phosphatase labeled secondary anti-IgG antibody. The addition of 1-naphthyl phosphate substrate resulted in the production of an electrochemically active product, 1-naphthol, which was monitored by using differential pulse voltammetry (DPV). The assay exhibited excellent sensitivity and specificity having a dynamic response range of 0.01 pg mL(-1) to 10 μg mL(-1) for diuron with a limit of detection of around 0.1 pg mL(-1) (n = 3) in standard water samples. The micro-cartridge coupled hapten-CNTs modified SPE provided an effective and efficient electrochemical immunoassay for the real-time monitoring of pesticides samples with a very high degree of sensitivity.

Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

International Nuclear Information System (INIS)

Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

2014-01-01

Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO 4 /HNO 3 . • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO 4 /HNO 3 treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process

Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

Energy Technology Data Exchange (ETDEWEB)

Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili, E-mail: ziliyu@scu.edu.cn

2014-10-30

Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO{sub 4}/HNO{sub 3}. • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO{sub 4}/HNO{sub 3} treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

Rapid, general synthesis of PdPt bimetallic alloy nanosponges and their enhanced catalytic performance for ethanol/methanol electrooxidation in an alkaline medium.

Science.gov (United States)

Zhu, Chengzhou; Guo, Shaojun; Dong, Shaojun

2013-01-14

We have demonstrated a rapid and general strategy to synthesize novel three-dimensional PdPt bimetallic alloy nanosponges in the absence of a capping agent. Significantly, the as-prepared PdPt bimetallic alloy nanosponges exhibited greatly enhanced activity and stability towards ethanol/methanol electrooxidation in an alkaline medium, which demonstrates the potential of applying these PdPt bimetallic alloy nanosponges as effective electrocatalysts for direct alcohol fuel cells. In addition, this simple method has also been applied for the synthesis of AuPt, AuPd bimetallic, and AuPtPd trimetallic alloy nanosponges. The as-synthesized three-dimensional bimetallic/trimetallic alloy nanosponges, because of their convenient preparation, well-defined sponge-like network, large-scale production, and high electrocatalytic performance for ethanol/methanol electrooxidation, may find promising potential applications in various fields, such as formic acid oxidation or oxygen reduction reactions, electrochemical sensors, and hydrogen-gas sensors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete

International Nuclear Information System (INIS)

Simescu, Florica; Idrissi, Hassane

2008-01-01

We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 . After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete

Directory of Open Access Journals (Sweden)

Florica Simescu and Hassane Idrissi

2008-01-01

Full Text Available We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca10(PO46(OH2. After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

Minimizing electrode contamination in an electrochemical cell

Science.gov (United States)

Kim, Yu Seung; Zelenay, Piotr; Johnston, Christina

2014-12-09

An electrochemical cell assembly that is expected to prevent or at least minimize electrode contamination includes one or more getters that trap a component or components leached from a first electrode and prevents or at least minimizes them from contaminating a second electrode.

A highly sensitive electrochemical sensor for the determination of methanol based on PdNPs@SBA-15-PrEn modified electrode.

Science.gov (United States)

Karimi, Ziba; Shamsipur, Mojtaba; Tabrizi, Mahmoud Amouzadeh; Rostamnia, Sadegh

2018-05-01

In this study, a novel electrochemical sensor for the determination of methanol based on palladium nanoparticles supported on Santa barbara amorphous-15- PrNHEtNH 2 (PdNPs@SBA-15-PrEn) as nanocatalysis platform is presented. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical methods are employed to characterize the PdNPs@SBA-15-PrEn nanocomposite. The Nafion-Pd@SBA-15-PrEn modified glassy carbon electrode (Nafion-PdNPs@SBA-15-PrEn/GCE) displayed the high electrochemical activity and excellent catalytic characteristic for electro-oxidation of methanol in an alkaline solution. The electro-oxidation performance of the proposed sensor was investigated using cyclic voltammetry (CV) and amperometry. The sensor exhibits a good sensitivity of 0.0905 Amol -1 Lcm -2 , linear range of 20-1000 μM and the corresponding detection limit of 12 μM (3σ). The results demonstrate that the Nafion-PdNPs@SBA-15-PrEn/GCE has potential as an efficient and integrated sensor for methanol detection. Copyright © 2018 Elsevier Inc. All rights reserved.

Severe Vaginal Burns in a 5-Year-Old Girl Due to an Alkaline Battery in the Vagina.

Science.gov (United States)

Semaan, Alexander; Klein, Tobias; Vahdad, Mohammad Reza; Boemers, Thomas M; Pohle, Rebecca

2015-10-01

The ingestion or insertion of alkaline batteries in the body can cause severe damage to hollow organs. We report here a case of severe vaginal burns in a young patient caused by an alkaline battery. A 5-year-old girl presented to our outpatient department with pelvic pain and vaginal discharge. Further workup suggested the presence of a vaginal foreign body. Under general anesthesia, an alkaline battery was removed from her vagina, which showed severe burns with partial-thickness necrosis. Complete healing was confirmed at 3 months after initial presentation. In this rare case of an alkaline battery present in the vagina of a prepubescent girl, we discuss the available treatment and management options in comparison to similar previously reported cases. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

CaCu3Ti4O12: A Bifunctional Perovskite Electrocatalyst for Oxygen Evolution and Reduction Reaction in Alkaline Medium

International Nuclear Information System (INIS)

Kushwaha, H.S.; Halder, Aditi; Thomas, P.; Vaish, Rahul

2017-01-01

Highlights: •A cost effective double perovskite CaCu 3 Ti 4 O 12 have been synthesized using oxalate precursor method. •CCTO electrocatalyst exhibit enhanced bifunctional electrocatalytic activities. •CCTO electrocatalyst have lower overpotential and higher mass activity as compared to noble metal oxide and well-known perovskite catalysts. •Electrochemical impedance spectroscopy investigations of oxygen reactions on perovskite surfaces. -- Abstract: Perovskite oxides are prominent materials as the bifunctional electrocatalysts for both oxygen reduction/evolution reactions (ORR/OER) for the electrochemical energy conversion and storage using regenerative fuel cells and rechargeable metal-air batteries. In this work, a quadruple perovskite CaCu 3 Ti 4 O 12 has been synthesized oxalate precursor route. X-ray diffraction pattern shows phase purity of the synthesized electrocatalyst. The synthesized CCTO electrocatalyst have crystallite size of 26 nm. Electrochemical investigations reveal that CCTO exhibit efficient catalytic activity. More interestingly, an extremely high OER activity is observed for CCTO electrocatalysts which is found superior than similar class of perovskites. Additionally, CCTO shows efficient ORR activity with an onset potential of 0.83 V which is better than that of Pt/C catalyst (≈0.94 V). These results demonstrate the significant potential of CCTO perovskite as a bifunctional electrode material for alkaline fuel cells and metal-air batteries.

Treatment of Radioactive Organic Wastes by an Electrochemical Oxidation

International Nuclear Information System (INIS)

Kim, K.H.; Ryue, Y.G.; Kwak, K.K.; Hong, K.P.; Kim, D.H.

2007-01-01

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 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)

Application of electrochemical techniques in fuel reprocessing- an overview

Energy Technology Data Exchange (ETDEWEB)

Rao, M K; Bajpai, D D; Singh, R K [Power Reactor Fuel Reprocessing Plant, Tarapur (India)

1994-06-01

The operating experience and development work over the past several years have considerably improved the wet chemical fuel reprocessing PUREX process and have brought the reprocessing to a stage where it is ready to adopt the introduction of electrochemical technology. Electrochemical processes offer advantages like simplification of reprocessing operation, improved performance of the plant and reduction in waste volume. At Power Reactor Fuel Reprocessing plant, Tarapur, work on development and application of electrochemical processes has been carried out in stages. To achieve plant scale application of these developments, a new electrochemical cycle is being added to PUREX process at PREFRE. This paper describes the electrochemical and membrane cell development activities carried out at PREFRE and their current status. (author). 5 refs., 4 tabs.

Corrosion of copper in alkaline chloride environments

International Nuclear Information System (INIS)

King, F.

2002-08-01

The available literature information on the corrosion and electrochemical behaviour of copper in alkaline environments has been reviewed. The purpose of the review was to assess the impact of an alkaline plume from cementitious material on the corrosion behaviour of a copper canister in an SKB-3 type repository. The effect of the evolution of the environmental conditions within the repository have been considered, including the effects of temperature, redox conditions, pore-water salinity and pH. If the pore-water pH increases prior to the establishment of anoxic conditions, the canister surface will passivate as the pore-water pH exceeds a value of ∼ pH 9. Passivation will result from the formation of a duplex Cu 2 O/Cu(OH) 2 film. The corrosion potential will be determined by the equilibrium potential for the Cu 2 O/Cu(OH) 2 couple under oxic conditions, or by the Cu/Cu 2 O redox couple under anoxic conditions (in the absence of sulphide). Pitting corrosion is only likely to occur early in the evolution of the repository environment, whilst the canister is still relatively cool ( 2 available to support localised corrosion, and prior to the increase in pore-water pH and salinity. The subsequent increase in canister surface temperature, pore-water pH and salinity, and decrease in O 2 will make pit initiation less likely, although the canister will remain passive provided the pore-water pH is maintained above pH 9. The higher the pore-water pH, the more strongly the canister is passivated and the less likely the surface is to undergo localised attack. If the pore-water salinity increases prior to the increase in pH, there could be a period of active canister corrosion before passivation occurs.Under these circumstances, the corrosion potential will be a true mixed potential, determine by the relative kinetics of Cu dissolution as CuCl 2 - and of the reduction of O 2 . The development of anoxic conditions and an increase in pore-water sulphide concentration will

Detection of pyrrolizidine alkaloids using flow analysis with both acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence

International Nuclear Information System (INIS)

Gorman, Bree A.; Barnett, Neil W.; Bos, Richard

2005-01-01

For the first time, analytically useful chemiluminescence was elicited from the reactions of the pyrrolizidine alkaloids. Heliotrine, retronecine, supinine, monocrotaline and echinatine N-oxide yielded chemiluminescence upon reaction with tris(2,2'-bipyridyl)ruthenium(II) whilst lasiocarpine, its N-oxide and supinine elicited light upon reaction with acidic potassium permanganate. Detection limits for heliotrine were 1.25 x 10 -7 M and 9 x 10 -9 M for tris(2,2'-bipyridyl)ruthenium(III) perchlorate with flow injection analysis (FIA) and the silica-immobilised reagent (4-[4-(dichloromethylsilanyl)-butyl]-4'-methyl-2,2'-bipyridine)bis (2,2'-bipyridyl)ruthenium(II) with sequential injection analysis (SIA), respectively. Lasiocarpine was detectable at 1.4 x 10 -7 M using acidic potassium permanganate with FIA. Additionally, the silica-immobilised reagent was optimised with respect to the oxidant (ammonium ceric nitrate) concentration and the aspiration times which afforded a detection limit for codeine of 5 x 10 -10 M using SIA

Comparative study of polypyrrole films electrosynthesized in alkaline and acid solutions

International Nuclear Information System (INIS)

Lehr, I.L.; Quinzani, O.V.; Saidman, S.B.

2009-01-01

The influence of the pH of electropolymerization solutions on the properties of polypyrrole films has been studied using potentiodynamic techniques and faradaic impedance spectroscopy. Scanning electron microscopy (SEM), IR and Raman spectroscopies, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were also used for products characterization. Results indicate that, contrary to what happen with the polymer electrogenerated in acid solutions, the films prepared in alkaline media are stable and present good electrochemical activity in basic solutions. Possible explanations for the observed differences are discussed and it is proposed that the pH of electropolymerization medium directly affects chains organization. Electrosynthesis in solutions of increased basicity results in a more compact and closed polymer structure.

Treatment of fast reactor liquid waste- electrochemical method

International Nuclear Information System (INIS)

Mahato, Swapan Kumar; Sudha, R.; Anthonysamy, S.; Muralidaran, P.

2015-01-01

During the operation of fast reactors, components get wetted by sodium. The sodium wetted primary components such as pumps and intermediate heat exchangers (IHX) in fast reactors are cleaned free of sodium followed by suitable chemical decontamination process before taking them for maintenance or for disposal. This helps in reduction of radiation dose to the operating personnel. Sodium cleaning and decontamination generates large volumes of liquid effluent. The activity in the liquid effluent during sodium cleaning/decontamination is due to 22 Na, 54 Mn, 58 Co, 60 Co, 59 Fe, 137 Cs and 134 Cs. It is required to chemically treat the effluent to reduce the activity levels prior to storage in tanks and transportation to the waste management facility for final disposal. Conventionally the ion exchange method is used for removal of radionuclides which produces large quantities of secondary waste. A method which is suitable both for removal of radionuclides present in low concentration and that avoids generation of large quantities of secondary waste is required. Hence an electrochemical method for metal ion removal is attempted in this work which produces little or no secondary waste. Electrochemical method towards removal of manganese ions was finalized earlier using reticulated vitreous carbon (RVC) from simulated decontamination solution containing a mixture of sulphuric and phosphoric acids. In continuation of the experiments for the removal of cesium ions from simulated cleaning solution which has an alkaline pH, a thin film of nickel hexacyanoferrate (NiHCF) was deposited electrochemically on the surface of RVC. Hexacyanoferrates are known for selectively binding cesium. This NiHCF coated RVC was used for electrodeposition of Cs ions. NiHCF coated and Cs deposited RVC was characterized using SEM/EDX analysis. EDX analysis confirms the presence of Cs on NiHCF coated RVC. (author)

A study on the mechanism of stress corrosion cracking of duplex stainless steels in hot alkaline-sulfide solution

Science.gov (United States)

Chasse, Kevin Robert

. Environments having different ionic concentrations of inorganic salts, i.e. sodium hydroxide, sodium sulfide, and sodium chloride, were used to understand the effect of liquor alkalinity, percent sulfidity, and chloride content on the corrosion and SCC behavior. Hydrogen embrittlement of S32205 was studied to understand the electrochemical conditions and fracture features associated with this failure mode. The results showed that there is an appreciable increase in the susceptibility of DSS to SCC in the presence of sulfide and chloride in hot alkaline environments. Sulfide and chloride adsorption at active sites on the metal surface caused unstable passivity and defective film formation. Chloride and sulfide available at the electrolyte/film surface reduced the charge transfer resistance and shifted the response of the films to lower frequencies indicating the films became more defective. The surface films had an outer, discontinuous layer, and an inner, barrier layer. Fe, Mo, and Mn were selectively dissolved in hot alkaline environments. The onset of SCC was related to the extent of selective dissolution and was consistent with a slip-step dissolution mechanism. Selective corrosion of the austenite phase depended on percent sulfidity and liquor alkalinity. Chlorides enhanced crack initiation and coalescence along the austenite/ferrite boundaries. Crack initiation and transgranular growth strongly depended on the phase distribution in the banded microstructure of DSS. These findings will augment understanding of SCC in this alloy-environment combination and facilitate materials selection in hot alkaline-sulfide environments, particularly in the petrochemical, nuclear, chemical processing, and pulp and paper industries.

Electrochemical depth profiling of multilayer metallic structures: An aluminum brazing sheet

DEFF Research Database (Denmark)

Afshar, F. Norouzi; Ambat, R.; Kwakernaak, C.

2012-01-01

Combinatory localized electrochemical cell and glow discharge optical emission spectrometry (GDOES) measurements were performed to obtain a thorough in depth electrochemical characterization of an aluminum brazing sheet. By defining electrochemical criteria i.e. breakdown potential, corrosion...... potential, cathodic and anodic reactivities, and tracking their changes as a function of depth, the evolution of electrochemical responses through out the material thickness were analyzed and correlated to the corresponding microstructural features. Polarization curves in 1wt% NaCl solution at pH 2.8 were...... obtained at different depths from the surface using controlled sputtering in a glow discharge optical emission spectrometer as a sample preparation technique. The anodic and cathodic reactivity of the top surface areas were significantly higher than that of the bulk, thus indicating these areas to be more...

Electrochemical oxidation of acid black 210 dye on the boron-doped diamond electrode in the presence of phosphate ions: Effect of current density, pH, and chloride ions

International Nuclear Information System (INIS)

Costa, Carla Regina; Montilla, Francisco; Morallon, Emilia; Olivi, Paulo

2009-01-01

The electrochemical oxidation of acid black 210 dye (AB-210) on the boron-doped diamond (BDD) was investigated under different pH conditions. The best performance for the AB-210 oxidation occurred in alkaline phosphate solution. This is probably due to oxidizing agents such as phosphate radicals and peroxodiphosphate ions, which can be electrochemically produced with good yields on the BDD anode, mainly in alkaline solution. Under this condition, the COD (chemical oxygen demand) removal was higher than that obtained from the model proposed by Comninellis. Electrolyses performed in phosphate buffer and in the presence of chloride ions resulted in faster COD and color removals in acid and neutral solutions, but in alkaline phosphate solution, a better performance in terms of TOC removal was obtained in the absence of chloride. Moreover, organochloride compounds were detected in all electrolyses performed in the presence of chloride. The AB-210 electrooxidation on BDD using phosphate as supporting electrolyte proved to be interesting since oxidizing species generated from phosphate ions were able to completely degrade the dye without producing organochloride compounds.

Use of lignite fly ash as an additive in alkaline stabilisation and pasteurisation of wastewater sludge

Energy Technology Data Exchange (ETDEWEB)

Kocaer, F.O.; Alkan, U.; Baskaya, H.S. [Uludag University, Bursa (Turkey). Faculty of Engineering & Architecture

2003-10-01

The possibility of using lignite fly ash in low doses for reducing the pathogen levels in wastewater sludge was investigated. The results showed that using fly ash alone in doses of 40%,80% and 120% (on a dry weight basis), did not produce an alkaline environment for an efficient removal of pathogens. However, using fly ash in conjunction with the minimum amount of quicklime may act as an effective way of fecal coliform removal in both alkaline stabilisation and pasteurisation processes. It was shown that using fly ash in doses of 80% and 120% in alkaline stabilisation and pasteurisation processes prevented the pH decays and regrowth of pathogens during 60 days of storage period. The results of the study confirmed that alkaline pasteurisation process produces a product which is more resistant to pH decays and regrowth of fecal coliforms compared to that of alkaline stabilisation. Consequently, the overall results of this study indicated that the minimum lime and fly ash dosages required to generate a Class B biosolid were 10-15% and 80%, respectively. On the other hand, heating sludge to 50{degree}C prior to the addition of 10-15% quicklime and 80% fly ash followed by further heating to 70{degree}C and then sustaining at this temperature for 30 minutes were sufficient to generate a Class A biosolid.

Oxidation of volatile organic compound vapours by potassium permanganate in a horizontal permeable reactive barrier under unsaturated conditions: experiments and modeling

NARCIS (Netherlands)

Ghareh Mahmoodlu, Mojtaba|info:eu-repo/dai/nl/357287746

2014-01-01

In this research we evaluated the potential of using solid potassium permanganate to create a horizontal permeable reactive barrier (HPRB) for oxidizing VOC vapours in the unsaturated zone. We have performed batch experiments, short column, and long column experiments, and have fully analyzed the

Passive neutralization of acid mine drainage using basic oxygen furnace slag as neutralization material: experimental and modelling

CSIR Research Space (South Africa)

Zvimba, JN

2015-12-01

Full Text Available emission 147 spectrometry (ICP-OES) (Varian: Vista Pro CCD Simultaneous ICP-OES). The pH, acidity, 148 alkalinity of the AMD were determined using a Mettler Toledo Auto-titrator following 149 filtration. Fe(II) was determined using standard permanganate...

Fe(II) oxidation during acid mine drainage neutralization in a pilot-scale sequencing batch reactor

CSIR Research Space (South Africa)

Zvimba, JN

2013-10-01

Full Text Available crystallization for metal content using ICP-OES (Varian: Vista Pro CCD Simultaneous ICP- OES). The pH, acidity and alkalinity of the AMD were determined using a Mettler Toledo Auto-titrator following filtration. Fe(II) was determined by standard permanganate...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 117; Issue 1. Kinetic, mechanistic and spectral investigation of ruthenium (III)-catalysed oxidation of atenolol by alkaline permanganate (stopped-flow technique). Rahamatalla M Mulla Gurubasavaraj C Hiremath Sharanappa T Nandibewoor. Full Papers Volume 117 ...

Sulfur-adlayer-coated gold electrode for the in vitro electrochemical detection of uric acid in urine.

Science.gov (United States)

Miah, Md Rezwan; Alam, Muhammad Tanzirul; Ohsaka, Takeo

2010-06-11

The present article demonstrates the electrochemical oxidation of uric acid (UA) at sulfur-adlayer-coated gold (S-Au) electrode in alkaline media. At S-Au electrode, UA oxidized at a significantly lower overpotential with a higher current density as compared to the bare Au electrode. The oxidation of UA at the S-Au electrode is highly selective in the presence of the other commonly existing bio-molecules in urine. The proposed electrochemical sensor not only exhibited good reproducibility, but also showed a fast amperometric response to UA in the concentration range of 0.0025-5 mM with a low detection limit of 0.4 microM. Copyright 2010. Published by Elsevier B.V.

Electrochemical treatment of an oxide material, application to superconductors, and obtained superconductors

International Nuclear Information System (INIS)

Grenier, J.C.; Pouchard, M.; Wattiaux, A.

1991-01-01

The present invention describes the electrochemical treatment of a superconductor oxide so as to modify its stoichiometry. These materials comprise in their anionic lattice oxygenated and hydrogenated species. These treated materials are prepared by an electrochemical process in which the oxide is an electrode in a liquid electrolysis. 3 refs., 3 figs

Test Concept for Advanced Oxidation Techniques

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Mortensen, Lars

advanced on-site oxidation tests. The remediation techniques included are electrochemical oxidation, photochemical/photocatalytic oxidation, ozone, hydrogen peroxide, permanganate, and persulfate among others. A versatile construction of the mobile test unit makes it possible to combine different...

Electrochemical behavior of labetalol at an ionic liquid modified carbon paste electrode and its electrochemical determination

Directory of Open Access Journals (Sweden)

Zhang Yan-Mei

2013-01-01

Full Text Available Electrochemical behavior of labetalol (LBT at carbon paste electrode (CPE and an ionic liquid1-benzyl-3-methylimidazolehexafluorophosphate([BnMIM]PF6modified carbon paste electrode([BnMIM]PF6/CPEin Britton-Robinson buffer solution (pH 2.0 was investigated by cyclic voltammetry (CV and square wave voltammetric (SWV. The experimental results showed that LBT at both the bare CPE and [BnMIM]PF6/CPEshowed an irreversible oxidation process, but at [BnMIM]PF6/CPE its oxidation peak current increased greatly and the oxidation peak potential shifted negatively. The electrode reaction process is a diffusion-controlled process involving one electron transferring accompanied by a participation of one proton at [BnMIM]PF6/CPE. At the same time, the electrochemical kinetic parameters were determined. Under the optimized electrochemical experimental conditions, the oxidation peak currents were proportional to LBT concentration in the range of 7.0 x 10-6-1.0 x 10-4 mol L-1 with the limit of detection(LOD, S/N=3 of 4.810 x 10-8 mol L-1and the limit of quantification(LOQ, S/N=10 of 1.60 x 10-7 mol L-1, respectively. The proposed method was successfully applied in the determination of LBT content in commercial tablet samples.

An extensive study of electrochemical behavior of brimonidine and its determination at glassy carbon electrode

International Nuclear Information System (INIS)

Aleksić, Mara M.; Radulović, Valentina; Agbaba, Danica; Kapetanović, Vera

2013-01-01

Highlights: • The electrochemical behavior of BRIM was investigated by CV, DPV and SWV at GCE. • The effects of pH, scan rate and BRIM concentriation was studied. • The nature of the electrode process, and the mechanism scheme was proposed. • DPV method was developed for the estimation of BRIM in the Alphagan eye drops. -- Abstract: The electrochemical behavior of brimonidine (BRIM), an antiglaucoma agent applied in therapy for lowering high intraocular pressure, was investigated by cyclic voltammetry, differential pulse voltammetry and square wave voltammetry using a glassy carbon electrode (GCE). The reduction of BRIM occurs as one-step quasi-reversible reaction in acid and neutral medium, reaching the full reversibility in alkaline solutions. Reduction process involves the transfer of two electrons and two protons at the pyrazine ring of quinoxaline moiety, forming a dihydro-derivative. In acid and neutral solutions, brimonidine reduction product is partly oxidized to its hydroxy-derivative. BRIM is also oxidized irreversibly with the transfer of one electron and one proton at secondary amine moiety. The effects of pH of the electrolyte solution, scan rate and BRIM concentration were monitored. The nature of the electrode process was found to be controlled by the adsorption at pH > 6 and the total surface concentration of brimonidine adsorbed onto the GCE surface at pH 7, Γ BRIM = 1.35 × 10 −10 mol cm −2 was obtained. Based on this study, differential pulse voltammetric method was developed, validated and suggested for rapid electroanalytical determination of the low concentration of brimonidine. The linearity was achieved within the concentration range from 5 × 10 −7 to 5 × 10 −6 M with LOD = 1.6 × 10 −7 M and LOQ = 5.3 × 10 −7 M. The method was applied for brimonidine determination in pharmaceutical dosage form, eye drops

Progress of research on the influence of alkaline cation and alkaline solution on bentonite properties

International Nuclear Information System (INIS)

Ye Weimin; Zheng Zhenji; Chen Bao; Chen Yonggui

2011-01-01

Based on the previous laboratory studies and numerical simulation on bentonite in alkaline environments, the effects of alkaline cation and alkaline solution on mineral composition, microstructure, swelling capacity and hydraulic properties of bentonite are emphasized in this paper, temperature, pH values and concentration are discussed as main affecting factors. When bentonite is exposed to alkaline cation or alkaline solution, microstructure of bentonite will be changed due to the dissolution of montmorillonite and the formation of secondary minerals, which results in the decrease of swelling pressure. The amount of the reduction of swelling pressure depends on the concentration of alkaline solution. Temperature, polyvalent cation, salinity and concentration are the main factors affecting hydraulic properties of bentonite under alkaline conditions. Therefore, future research should focus on the mechanism of coupling effects of weak alkaline solutions on the mineral composition, microstructure, swelling capacity and hydraulic properties of bentonite under different temperatures and different pH values. (authors)

Electrochemical performance of high specific capacity of lithium-ion cell LiV3O8//LiMn2O4 with LiNO3 aqueous solution electrolyte

International Nuclear Information System (INIS)

Zhao Mingshu; Zheng Qingyang; Wang Fei; Dai Weimin; Song Xiaoping

2011-01-01

Research highlights: → In this paper, the electrochemical performance of aqueous rechargeable lithium battery with LiV 3 O 8 and LiMn 2 O 4 in saturated LiNO 3 electrolyte is studied. → The electrochemical performance tests show that the specific capacity of LiMn 2 O 4 using as the cathode of ARLB is similar to that of ordinary lithium-ion battery with organic electrolyte, which works much better than the formerly reported. → In addition, the cell systems exhibit good cycling performance. Therefore, it has great potential comparing with other batteries such as lead acid batteries and alkaline manganese batteries. - Abstract: The electrochemical performance of aqueous rechargeable lithium battery (ARLB) with LiV 3 O 8 and LiMn 2 O 4 in saturated LiNO 3 electrolyte is studied. The results indicate that these two electrode materials are stable in the aqueous solution and no hydrogen or oxygen produced, moreover, intercalation/de-intercalation of lithium ions occurred within the range of electrochemical stability of water. The electrochemical performance tests show that the specific capacity of LiMn 2 O 4 using as the cathode of ARLB is similar to that of ordinary lithium-ion battery with organic electrolyte, which works much better than the formerly reported. In addition, the cell systems exhibit good cycling performance. Therefore, it has great potential comparing with other batteries such as lead acid batteries and alkaline manganese batteries.

Alizarin Red S as an electrochemical indicator for saccharide recognition

Energy Technology Data Exchange (ETDEWEB)

Schumacher, Soeren, E-mail: soeren.schumacher@ibmt.fraunhofer.de [Fraunhofer Institute for Biomedical Engineering, Am Muehlenberg 13, 14476 Potsdam (Germany); Nagel, Thomas; Scheller, Frieder W.; Gajovic-Eichelmann, Nenad [Fraunhofer Institute for Biomedical Engineering, Am Muehlenberg 13, 14476 Potsdam (Germany)

2011-07-30

Graphical abstract: Display Omitted Highlights: > Transfer of the established Alizarin Red S (ARS) for saccharide-boronic acid interaction to electrochemistry. > Investigation of electrochemical behaviour of ARS and its interaction with phenylboronic acid at pH 7.4. > Through addition of fructose the ARS was displaced. > Displaced ARS could be monitored electrochemically corresponding to the used fructose concentration. - Abstract: In addition to the well-established spectroscopic Alizarin Red S (ARS) assay for the determination of binding constants between arylboronic acids and different saccharides, we report the use of ARS as a reporter in an electrochemical set-up. The electrochemical properties of ARS, the binding to phenyl boronic acid (PBA) and the competition with fructose in phosphate buffer at pH 7.4 were investigated by cyclic voltammetry (CV). By choosing a negative scan direction (starting at +0.2 V), a quasi-reversible process was detected at E{sup 0}' = -0.59V with {Delta}E{sub p} = 0.1V. An irreversible oxidation peak at +0.42 V could also be detected. These peaks are characterised both as a 2-proton-2-electron transfer and corresponds to the oxidation and reduction of the anthraquinone or the ortho-quinone moiety. After addition of phenylboronic acid a new oxidation peaks occurred at -0.42 V which correlates with the ARS-PBA interaction. The peak current increased with increasing phenylboronic acid concentration according to the release of BA and formation of the ARS-PBA ester. After addition of fructose the peak current decreases again, in proportion to the fructose concentration, enabling the use of ARS as an electrochemical reporter for fructose detection up to 50 mM. Also the interaction with other cis-diol containing compounds such as sorbitol, mannitol, glucose and mannose was investigated and a dependence based on already published binding constants to phenylboronic acid could be shown.

Alizarin Red S as an electrochemical indicator for saccharide recognition

International Nuclear Information System (INIS)

Schumacher, Soeren; Nagel, Thomas; Scheller, Frieder W.; Gajovic-Eichelmann, Nenad

2011-01-01

Graphical abstract: Display Omitted Highlights: → Transfer of the established Alizarin Red S (ARS) for saccharide-boronic acid interaction to electrochemistry. → Investigation of electrochemical behaviour of ARS and its interaction with phenylboronic acid at pH 7.4. → Through addition of fructose the ARS was displaced. → Displaced ARS could be monitored electrochemically corresponding to the used fructose concentration. - Abstract: In addition to the well-established spectroscopic Alizarin Red S (ARS) assay for the determination of binding constants between arylboronic acids and different saccharides, we report the use of ARS as a reporter in an electrochemical set-up. The electrochemical properties of ARS, the binding to phenyl boronic acid (PBA) and the competition with fructose in phosphate buffer at pH 7.4 were investigated by cyclic voltammetry (CV). By choosing a negative scan direction (starting at +0.2 V), a quasi-reversible process was detected at E 0 ' = -0.59V with ΔE p = 0.1V. An irreversible oxidation peak at +0.42 V could also be detected. These peaks are characterised both as a 2-proton-2-electron transfer and corresponds to the oxidation and reduction of the anthraquinone or the ortho-quinone moiety. After addition of phenylboronic acid a new oxidation peaks occurred at -0.42 V which correlates with the ARS-PBA interaction. The peak current increased with increasing phenylboronic acid concentration according to the release of BA and formation of the ARS-PBA ester. After addition of fructose the peak current decreases again, in proportion to the fructose concentration, enabling the use of ARS as an electrochemical reporter for fructose detection up to 50 mM. Also the interaction with other cis-diol containing compounds such as sorbitol, mannitol, glucose and mannose was investigated and a dependence based on already published binding constants to phenylboronic acid could be shown.

Detection of pyrrolizidine alkaloids using flow analysis with both acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence

Energy Technology Data Exchange (ETDEWEB)

Gorman, Bree A. [School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217 (Australia); Barnett, Neil W. [School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217 (Australia)]. E-mail: barnie@deakin.edu.au; Bos, Richard [School of Biological and Chemical Sciences, Deakin University, Geelong, Vic. 3217 (Australia)

2005-06-13

For the first time, analytically useful chemiluminescence was elicited from the reactions of the pyrrolizidine alkaloids. Heliotrine, retronecine, supinine, monocrotaline and echinatine N-oxide yielded chemiluminescence upon reaction with tris(2,2'-bipyridyl)ruthenium(II) whilst lasiocarpine, its N-oxide and supinine elicited light upon reaction with acidic potassium permanganate. Detection limits for heliotrine were 1.25 x 10{sup -7} M and 9 x 10{sup -9} M for tris(2,2'-bipyridyl)ruthenium(III) perchlorate with flow injection analysis (FIA) and the silica-immobilised reagent (4-[4-(dichloromethylsilanyl)-butyl]-4'-methyl-2,2'-bipyridine)bis (2,2'-bipyridyl)ruthenium(II) with sequential injection analysis (SIA), respectively. Lasiocarpine was detectable at 1.4 x 10{sup -7} M using acidic potassium permanganate with FIA. Additionally, the silica-immobilised reagent was optimised with respect to the oxidant (ammonium ceric nitrate) concentration and the aspiration times which afforded a detection limit for codeine of 5 x 10{sup -10} M using SIA.

Silicon Priming Created an Enhanced Tolerance in Alfalfa (Medicago sativa L.) Seedlings in Response to High Alkaline Stress.

Science.gov (United States)

Liu, Duo; Liu, Miao; Liu, Xiao-Long; Cheng, Xian-Guo; Liang, Zheng-Wei

2018-01-01

Alkaline stress as a result of higher pH usually triggers more severe physiological damage to plants than that of saline stress with a neutral pH. In the present study, we demonstrated that silicon (Si) priming of alfalfa ( Medicago sativa L.) seedlings increased their tolerance to high alkaline stress situations. Gongnong No. 1 seedlings were subjected to alkaline stress simulated by 25 mM Na 2 CO 3 (pH 11.2). Alkaline stress greatly decreased the biomass and caused severe lodging or wilting of alfalfa seedlings. In contrast, the application of Si to alfalfa seedlings 36 h prior to the alkaline treatment significantly alleviated the damage symptoms and greatly increased the biomass and chlorophyll content. Because of being concomitant with increasing photosynthesis and water use efficiency, decreasing membrane injury and malondialdehyde content, and increasing peroxidase and catalase ascorbate activities in alfalfa leaves, thereby alleviating the triggered oxidative damage by alkaline stress to the plant. Furthermore, Si priming significantly decreased the accumulation of protein and proline content in alfalfa, thus reducing photosynthetic feedback repression. Si priming significantly accumulated more Na in the roots, but led to a decrease of Na accumulation and an increase of K accumulation in the leaves under alkaline stress. Meanwhile, Si priming decreased the accumulation of metal ions such as Mg, Fe, Mn, and Zn in the roots of alfalfa seedlings under alkaline stress. Collectively, these results suggested that Si is involved in the metabolic or physiological changes and has a potent priming effect on the alkaline tolerance of alfalfa seedlings. The present study indicated that Si priming is a new approach to improve the alkaline tolerance in alfalfa and provides increasing information for further exploration of the alkaline stress response at the molecular level in alfalfa.

Catechol-chitosan redox capacitor for added amplification in electrochemical immunoanalysis.

Science.gov (United States)

Yan, Kun; Liu, Yi; Guan, Yongguang; Bhokisham, Narendranath; Tsao, Chen-Yu; Kim, Eunkyoung; Shi, Xiao-Wen; Wang, Qin; Bentley, William E; Payne, Gregory F

2018-05-22

Antibodies are common recognition elements for molecular detection but often the signals generated by their stoichiometric binding must be amplified to enhance sensitivity. Here, we report that an electrode coated with a catechol-chitosan redox capacitor can amplify the electrochemical signal generated from an alkaline phosphatase (AP) linked immunoassay. Specifically, the AP product p-aminophenol (PAP) undergoes redox-cycling in the redox capacitor to generate amplified oxidation currents. We estimate an 8-fold amplification associated with this redox-cycling in the capacitor (compared to detection by a bare electrode). Importantly, this capacitor-based amplification is generic and can be coupled to existing amplification approaches based on enzyme-linked catalysis or magnetic nanoparticle-based collection/concentration. Thus, the capacitor should enhance sensitivities in conventional immunoassays and also provide chemical to electrical signal transduction for emerging applications in molecular communication. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of ethanol using permanganate-CdS quantum dot chemiluminescence system.

Science.gov (United States)

Abolhasani, Jafar; Hassanzadeh, Javad

2015-08-01

A novel and highly sensitive chemiluminescence (CL) method for the determination of ethanol was developed based on the CdS quantum dots (QDs)-permanganate system. It was found that KMnO4 could directly oxidize CdS QDs in acidic media resulting in relatively high CL emission. A possible mechanism was proposed for this reaction based on UV/Vis absorption, fluorescence and the generated CL emission spectra. However, it was observed that ethanol had a remarkable inhibition effect on this system. This effect was exploited in the determination of ethanol within the concentration range 12-300 µg/L, with detection at 4.3 µg/L. In order to evaluate the capability of presented method, it was satisfactorily utilized in the determination of alcohol in real samples. Copyright © 2014 John Wiley & Sons, Ltd.

Comparison of electrochemical corrosion behaviour of MgO and ZrO2 coatings on AM50 magnesium alloy formed by plasma electrolytic oxidation

International Nuclear Information System (INIS)

Liang, J.; Srinivasan, P. Bala; Blawert, C.; Dietzel, W.

2009-01-01

Two types of PEO coatings were produced on AM50 magnesium alloy using pulsed DC plasma electrolytic oxidation process in an alkaline phosphate and acidic fluozirconate electrolytes, respectively. The phase composition and microstructure of these PEO coatings were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion behaviour of the coated samples was evaluated by open circuit potential (OCP) measurements, potentiodynamic polarization tests, and electrochemical impedance spectroscopy (EIS) in neutral 0.1 M NaCl solution. The results showed that PEO coating prepared from alkaline phosphate electrolyte consisted of only MgO and on the other hand the one formed in acidic fluozirconate solution was mainly composed of ZrO 2 , MgF 2 . Electrochemical corrosion tests indicated that the phase composition of PEO coating has a significant effect on the deterioration process of coated magnesium alloy in this corrosive environment. The PEO coating that was composed of only MgO suffered from localized corrosion in the 50 h exposure studies, whereas the PEO coating with ZrO 2 compounds showed a much superior stability during the corrosion tests and provided an efficient corrosion protection. The results showed that the preparation of PEO coating with higher chemical stability compounds offers an opportunity to produce layers that could provide better corrosion protection to magnesium alloys.

Copper-zinc electrodeposition in alkaline-sorbitol medium: Electrochemical studies and structural, morphological and chemical composition characterization

Science.gov (United States)

de Almeida, M. R. H.; Barbano, E. P.; de Carvalho, M. F.; Tulio, P. C.; Carlos, I. A.

2015-04-01

The galvanostatic technique was used to analyze the electrodeposition of Cu-Zn on to AISI 1010 steel electrode from an alkaline-sorbitol bath with various proportions of the metal ions in the bath: Cu70/Zn30, Cu50/Zn50 and Cu30/Zn70. Coloration of Cu-Zn films were whitish golden, light golden, golden/gray depending on the Cu2+/Zn2+ ratios in the electrodeposition bath, deposition current density (jdep) and charge density (qdep). The highest current efficiency was ∼54.0%, at jdep -1.0 mA cm-2 and qdep 0.40 C cm-2 in the Cu70/Zn30 bath. Energy dispersive spectroscopy indicated that electrodeposits produced from the bath Cu70/Zn30 showed higher Cu content at lower jdep. Also, for same jdep the Cu content increased with qdep. Scanning electron microscopy showed that Cu-Zn electrodeposits of high quality were obtained from the Cu70/Zn30 bath, since the films were fine-grained, except the obtained at jdep -20.0 mA cm-2 and qdep 10.0 C cm-2. Also, these electrodeposits did not present cracks. X-ray analysis of the Cu-Zn electrodeposits obtained at jdep -8.0, -20.0 and -40.0 mA cm-2, in each case, with qdep 2.0 and 10.0 C cm-2, in the Cu70/Zn30 bath, suggested the occurrence of a mixture of the following phases, CuZn, CuZn5 and Cu5Zn8. Galvanostatic electrodeposits of Cu-Zn obtained from sorbitol-alkaline baths exhibited whitish golden color, with good prospects for industrial applications, especially for decorative purposes.

Electrochemical energy generation

International Nuclear Information System (INIS)

Kreysa, G.; Juettner, K.

1993-01-01

The proceedings encompass 40 conference papers belonging to the following subject areas: Baseline and review papers; electrochemical fuel cells; batteries: Primary and secondary cells; electrochemical, regenerative systems for energy conversion; electrochemical hydrogen generation; electrochemistry for nuclear power plant; electrochemistry for spent nuclear fuel reprocessing; energy efficiency in electrochemical processes. There is an annex listing the authors and titles of the poster session, and compacts of the posters can be obtained from the office of the Gesellschaft Deutscher Chemiker, Abteilung Tagungen. (MM) [de

Electrooxidation of 2-propanol compared ethanol on Pd electrode in alkaline medium

Energy Technology Data Exchange (ETDEWEB)

Su, Yuzhi; Xu, Changwei; Liu, Zhaoqing [School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006 (China); Liu, Jianping [Dongguan Entry-exit Inspection and Quarantine Bureau, Dongguan 511700 (China)

2009-10-20

Here, the oxidation activity of 2-propanol compared ethanol on Pd electrode has been studied in alkaline medium. We have used the amount of coulombs (coulometry) and apparent activation energy (E{sub a}) to measure the activity of alcohol electrooxidation. The amount of coulombs during alcohol electrooxidation for 2-propanol is much higher than that of ethanol showing that 2-propanol is more easily electrochemically oxidized than ethanol. The E{sub a} values of 2-propanol are lower than that of ethanol at the potential from -0.45 to -0.375 V which is usually used in direct alcohol fuel cells (DAFCs) indicating that 2-propanol shows better electrooxidation activity than ethanol. (author)

Corrosion of copper in alkaline chloride environments

Energy Technology Data Exchange (ETDEWEB)

King, F. [Integrity Corrosion Consulting Ltd., Calgary (Canada)

2002-08-01

The available literature information on the corrosion and electrochemical behaviour of copper in alkaline environments has been reviewed. The purpose of the review was to assess the impact of an alkaline plume from cementitious material on the corrosion behaviour of a copper canister in an SKB-3 type repository. The effect of the evolution of the environmental conditions within the repository have been considered, including the effects of temperature, redox conditions, pore-water salinity and pH. If the pore-water pH increases prior to the establishment of anoxic conditions, the canister surface will passivate as the pore-water pH exceeds a value of {approx} pH 9. Passivation will result from the formation of a duplex Cu{sub 2}O/Cu(OH){sub 2} film. The corrosion potential will be determined by the equilibrium potential for the Cu{sub 2}O/Cu(OH){sub 2} couple under oxic conditions, or by the Cu/Cu{sub 2}O redox couple under anoxic conditions (in the absence of sulphide). Pitting corrosion is only likely to occur early in the evolution of the repository environment, whilst the canister is still relatively cool (<40 deg C), whilst there is still O{sub 2} available to support localised corrosion, and prior to the increase in pore-water pH and salinity. The subsequent increase in canister surface temperature, pore-water pH and salinity, and decrease in O{sub 2} will make pit initiation less likely, although the canister will remain passive provided the pore-water pH is maintained above pH 9. The higher the pore-water pH, the more strongly the canister is passivated and the less likely the surface is to undergo localised attack. If the pore-water salinity increases prior to the increase in pH, there could be a period of active canister corrosion before passivation occurs.Under these circumstances, the corrosion potential will be a true mixed potential, determine by the relative kinetics of Cu dissolution as CuCl{sub 2} - and of the reduction of O{sub 2}. The development

Patterned electrochemical deposition of copper using an electron beam

Directory of Open Access Journals (Sweden)

Mark den Heijer

2014-02-01

Full Text Available We describe a technique for patterning clusters of metal using electrochemical deposition. By operating an electrochemical cell in the transmission electron microscope, we deposit Cu on Au under potentiostatic conditions. For acidified copper sulphate electrolytes, nucleation occurs uniformly over the electrode. However, when chloride ions are added there is a range of applied potentials over which nucleation occurs only in areas irradiated by the electron beam. By scanning the beam we control nucleation to form patterns of deposited copper. We discuss the mechanism for this effect in terms of electron beam-induced reactions with copper chloride, and consider possible applications.

Treatability studies

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Studds, Phil

developed a mobile test unit including equipment for both standard and more advanced oxidation test directly on the site. The remediation techniques included are electrochemical oxidation, photochemical/photocatalytic oxidation, ozone, Fenton’s, permanganate, and persulfate among others. A versatile...

High Discharge Rate Electrodeposited Zinc Electrode for Use in Alkaline Microbattery

Directory of Open Access Journals (Sweden)

A. L. Nor Hairin

2012-01-01

Full Text Available High discharge rate zinc electrode is prepared from electrodeposition process. The electrolytic bath consists of zinc chloride as the metal source and ammonium chloride as the supporting electrolyte. The concentration of the supporting electrolyte is varied from zero until 4 M, while the concentration of zinc chloride is fixed at 2 M. The aim is to produce a porous zinc coating with an enhanced and intimate interfacial area per unit volume. These characteristics shall contribute towards reduced ohmic losses, improved active material utilization, and subsequently producing high rate capacity electrochemical cell. Nitrogen physisorption at 77 K is used to measure the BET surface area and pore volume density of the zinc electrodeposits. The electrodeposited zinc electrodes are then fabricated into alkaline zinc-air microbattery measuring 1 cm2 area x ca. 305 µm thick. The use of inorganic MCM-41 membrane separator enables the fabrication of a compact cell design. The quality of the electrodeposited zinc electrodes is gauged directly from the electrochemical performance of zinc-air cell. Zinc electrodeposits prepared from electrolytic bath of 2 M NH4Cl produces the highest discharge capacity.ABSTRAK: Elektrod zink dengan kadar discas tinggi telah dihasilkan dengan proses saduran elektrokimia. Takungan elektrolit terdiri daripada zink klorida sebagai sumber logam dan ammonium klorida sebagai elektrolit sokongan. Kepekatan elektrolit sokongan diubah daripada sifar hingga 4 M, sementara kepekatan zink klorida ditetapkan pada 2 M. Ini bertujuan untuk mendapatkan saduran zink yang poros dengan luas permukaan per unit isipadu dan sentuhan antaramuka yang dipertingkatkan. Ciri-ciri ini akan menyumbang terhadap pengurangan kehilangan disebabkan kerintangan, pertambahan dalam gunapakai bahan aktif dan akhirnya menghasilkan sel elektrokimia berprestasi tinggi. Physisorpsi nitrogen pada 77 K telah digunakan untuk mengukur luas permukaan BET dan isipadu liang

Quaternized poly(vinyl alcohol)/alumina composite polymer membranes for alkaline direct methanol fuel cells

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Chien, Wen-Chen; Chiu, Sheng-Shin

The quaternized poly(vinyl alcohol)/alumina (designated as QPVA/Al 2O 3) nanocomposite polymer membrane was prepared by a solution casting method. The characteristic properties of the QPVA/Al 2O 3 nanocomposite polymer membranes were investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), micro-Raman spectroscopy, and AC impedance method. Alkaline direct methanol fuel cell (ADMFC) comprised of the QPVA/Al 2O 3 nanocomposite polymer membrane were assembled and examined. Experimental results indicate that the DMFC employing a cheap non-perfluorinated (QPVA/Al 2O 3) nanocomposite polymer membrane shows excellent electrochemical performances. The peak power densities of the DMFC with 4 M KOH + 1 M CH 3OH, 2 M CH 3OH, and 4 M CH 3OH solutions are 28.33, 32.40, and 36.15 mW cm -2, respectively, at room temperature and in ambient air. The QPVA/Al 2O 3 nanocomposite polymer membranes constitute a viable candidate for applications on alkaline DMFC.

Electrochemical investigation on an acrylated thiophene

Energy Technology Data Exchange (ETDEWEB)

Hogervorst, A.C.R. (TNO Plastics and Rubber Research Inst., Delft (Netherlands)); Kock, T.J.J.M. (TNO Plastics and Rubber Research Inst., Delft (Netherlands)); Ruiter, B. de (TNO Plastics and Rubber Research Inst., Delft (Netherlands)); Waal, A. van der (TNO Plastics and Rubber Research Inst., Delft (Netherlands))

1993-03-22

The electrochemical behaviour of electropolymerized 2-(3-thienyl)ethyl acrylate (PAcrT) has been investigated, and compared to the behaviour of electropolymerized thiophene and 3-n-decylthiophene (PDT). The effect of electron beam irradiation on the electrochemical properties of these three polymers has been studied. It has been found that for PAcrT the oxidation wave shifts to higher potentials upon electron beam irradiation. For PDT a similar but smaller change occurs. We suggest that the shift of the oxidation wave of PAcrT is caused by cross-links, formed between the acrylate substituents, which fixate the main chain parts in twisted states and reduce the conjugation length. (orig.)

Advanced alkaline water electrolysis

International Nuclear Information System (INIS)

Marini, Stefania; Salvi, Paolo; Nelli, Paolo; Pesenti, Rachele; Villa, Marco; Berrettoni, Mario; Zangari, Giovanni; Kiros, Yohannes

2012-01-01

A short review on the fundamental and technological issues relevant to water electrolysis in alkaline and proton exchange membrane (PEM) devices is given. Due to price and limited availability of the platinum group metal (PGM) catalysts they currently employ, PEM electrolyzers have scant possibilities of being employed in large-scale hydrogen production. The importance and recent advancements in the development of catalysts without PGMs are poised to benefit more the field of alkaline electrolysis rather than that of PEM devices. This paper presents our original data which demonstrate that an advanced alkaline electrolyzer with performances rivaling those of PEM electrolyzers can be made without PGM and with catalysts of high stability and durability. Studies on the advantages/limitations of electrolyzers with different architectures do show how a judicious application of pressure differentials in a recirculating electrolyte scheme helps reduce mass transport limitations, increasing efficiency and power density.

Electrochemical Corrosion Behaviour of Alumina-Al 6061 and Silicon Carbide-Al 6061 Metal-Matrix Composites

International Nuclear Information System (INIS)

Mohamed, K.E.; Gad, M.M.A.; El-Sayed, A.A.; Moustafa, O.H.

2001-01-01

The electrochemical corrosion behaviour of powder metallurgy-processed metal-matrix composites (MMCs)based on Al alloy 6061 reinforced with particulate Al 2 O 3 or Sic has been studied in chloride-containing environment. Also, the corrosion behaviour of the unrein forced Al 6061 produced by the same route investigated. Electrochemical tests were conducted on composites containing 10 and 20 vo l% of both reinforced particulates. Potentiodynamic polarization tests have been carried out in neutral as well as acidic and alkaline de-aerated 10 -3 M Na CI solution. In the neutral environment, the addition of Al 2 O 3 particulates was found to shift both the corrosion potential (E corr ) and the break down potential (E b ) slightly into the positive direction irrespective of the volume fraction added (10 and 20 vo l%). On the other hand , Sic caused a shift of E corr into the active site while the E b value was slightly ennobled. For both composites, the corrosion current values at the break down potentials were almost the same as the unrein forced alloy. In an attempt to further clarify the role of both particulate addition, cathodic polarization runs were conducted in both acidic (ph 3) and alkaline (ph 9)solutions for 20 vo l% of Al 2 O 3 and 20 vo l% Sic composite specimens. This indicated that cathodic current values for Sic composites were higher than those corresponding to the unrein forced alloy 6061, and those for the Al 2 O 3 composites were lower

ALKALINE CARBONATE LEACHING PROCESS FOR URANIUM EXTRACTION

Science.gov (United States)

Thunaes, A.; Brown, E.A.; Rabbitts, A.T.

1957-11-12

A process for the leaching of uranium from high carbonate ores is presented. According to the process, the ore is leached at a temperature of about 200 deg C and a pressure of about 200 p.s.i.g. with a solution containing alkali carbonate, alkali permanganate, and bicarbonate ion, the bicarbonate ion functionlng to prevent premature formation of alkali hydroxide and consequent precipitation of a diuranate. After the leaching is complete, the uranium present is recovered by precipitation with NaOH.

The Impact of Hydrocalumites Additives on the Electrochemical Performance of Zinc-Nickel Secondary Cells

International Nuclear Information System (INIS)

Wen, Xing; Yang, Zhanhong; Xiao, Xiang; Yang, Huan; Xie, Xiaoe; Huang, Jianhang

2016-01-01

Hydrocalumites additives are synthesized and proposed as an anodic additive for Zinc/Nickel alkaline secondary batteries. The as-prepared additives are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). And the results illustrate that hydrocalumites additives are successfully prepared and have the typical structure of layered double hydroxides (LDHs). The effects of hydrocalumites additives on electrochemical performances of ZnO have been investigated by cyclic voltammetry (CV), tafel polarization tests, electrochemical impedance spectroscopy (EIS) and galvanostatic charge and discharge. Compared to the electrode with pure ZnO, the electrodes containing hydrocalumites additives show better reversibility, reveal better anti-corrosion property and exhibit more stable cycle performance. Especially when the electrode added with 12% (wt.) hydrocalumites, it exhibits the best cycle performance than the other electrodes. And its discharge capacity is about 450 mAh g −1 all the time, and hardly declines over all the 400 cycles. Based on these observations, the prepared hydrocalumites may be a promising and efficient additive for the ZnO electrode.

Electrochemical biosensors

CERN Document Server

Cosnier, Serge

2015-01-01

"This is an excellent book on modern electrochemical biosensors, edited by Professor Cosnier and written by leading international experts. It covers state-of-the-art topics of this important field in a clear and timely manner."-Prof. Joseph Wang, UC San Diego, USA 　"This book covers, in 13 well-illustrated chapters, the potential of electrochemical methods intimately combined with a biological component for the assay of various analytes of biological and environmental interest. Particular attention is devoted to the description of electrochemical microtools in close contact with a biological cell for exocytosis monitoring and to the use of nanomaterials in the electrochemical biosensor architecture for signal improvement. Interestingly, one chapter describes the concept and design of self-powered biosensors derived from biofuel cells. Each topic is reviewed by experts very active in the field. This timely book is well suited for providing a good overview of current research trends devoted to electrochemical...

A ternary nanocatalyst of Ni/Cr/Co oxides with high activity and stability for alkaline glucose electrooxidation

International Nuclear Information System (INIS)

Gu, Yingying; Yang, Haihong; Li, Benqiang; An, Yarui

2016-01-01

Highlights: • Ni-Cr-Co nanomaterial was synthesized by thermal decomposition method. • Ni 4 -Cr 1 -Co 1.5 has the highest GOR activity among the prepared catalysts. • A catalytic current density of 23.8 mA × cm −2 is attained for alkaline GOR. - Abstract: A novel ternary nanocatalyst of Ni-Cr-Co oxides is synthesized as anode electro-catalysts for glucose oxidation. The nanostructure is characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), which indicates that the catalyst particles are well dispersed with average size of 30 nm when the calcination temperature is 500 °C. The electrochemical performance is evaluated via cyclic voltammetry (CV). Compared with the bimetallic Ni-Cr and Ni-Co nanocatalysts, Ni-Cr-Co electrocatalysts exhibites more negative onset potential (0.4 V) and high oxidation peak current density (23.8 mA cm −2 ) in alkaline media towards glucose oxidation. Meanwhile, the results also show that the Ni-Cr-Co nanomaterial possesses good performance of anti-poisoning capability, reproducibility and long-time stability, which make it an excellent candidate for fuel cell electrocatalyst.

LDHs as electrode materials for electrochemical detection and energy storage: supercapacitor, battery and (bio)-sensor.

Science.gov (United States)

Mousty, Christine; Leroux, Fabrice

2012-11-01

From an exhaustive overview based on applicative academic literature and patent domain, the relevance of Layered Double Hydroxide (LDHs) as electrode materials for electrochemical detection of organic molecules having environmental or health impact and energy storage is evaluated. Specifically the focus is driven on their application as supercapacitor, alkaline or lithium battery and (bio)-sensor. Inherent to the high versatility of their chemical composition, charge density, anion exchange capability, LDH-based materials are extensively studied and their performances for such applications are reported. Indeed the analytical characteristics (sensitivity and detection limit) of LDH-based electrodes are scrutinized, and their specific capacity or capacitance as electrode battery or supercapacitor materials, are detailed.

Hydrogen storage material, electrochemically active material, electrochemical cell and electronic equipment

NARCIS (Netherlands)

2008-01-01

The invention relates to a hydrogen storage material comprising an alloy of magnesium. The invention further relates to an electrochemically active material and an electrochemical cell provided with at least one electrode comprising such a hydrogen storage material. Also, the invention relates to

An Electrochemical Investigation of Nano Cerium Oxide/Graphene as an Electrode Material for Supercapacitors

Directory of Open Access Journals (Sweden)

Mohammadreza Shishesaz

2015-01-01

In this paper, the effect of cationic and anionic ion sizes on the charge storage capability of graphene nanosheets, is investigated. Electrochemical properties of produced electrode are studied using cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS techniques, in 3M NaCl, NaOH and KOH electrolytes. Scanning electron microscopy (SEM is used to characterize the microstructure and nature of prepared electrode. SEM images and XRD patterns confirm the layered structure (12 nm thickness of the used graphene with an interlayer distance of 3.36 (Å. The electrochemical results and the ratio of q*O/q*T confirm a good charge storage and charge delivering capability of prepared electrode in 3M NaCl electrolyte. Charge/discharge cycling test shows a good reversibility and confirms that solution resistance will increase after 500 cycles.

Malonic acid: A potential reagent in decontamination processes for Ni-rich alloy surfaces

International Nuclear Information System (INIS)

Garcia, D.; Bruyere, V.I.E.; Bordoni, R.; Olmedo, A.M.; Morando, P.J.

2011-01-01

The ability of malonic acid as a dissolution agent toward synthetic Ni ferrite and Alloy 600 and 800 corrosion products was explored. Its performance in the dissolution kinetics of Ni ferrite powders was compared with the one of oxalic acid. Kinetic parameters were obtained and the dependency on external Fe(II) was modelled. Oxidized samples used in descaling tests were prepared by exposure of coupons of both alloys to lithiated aqueous solutions, under hydrothermal conditions and hydrogen overpressure, simulating PHWR conditions. Oxide layer morphology, the influence of exposure time to corrosive medium and LiOH concentration on its thickness were characterized. Descaling tests consisting on a two-stage method (a first oxidizing step with alkaline permanganate followed by a reducing step with oxalic or malonic acid were carried out). Results were compared to those obtained with a well known chemical cleaning formulation (APAC: Alkaline Permanganate Ammonium Citrate) used in decontamination of several reactors and loops and the competitiveness of malonic acid was demonstrated.

Malonic acid: A potential reagent in decontamination processes for Ni-rich alloy surfaces

Energy Technology Data Exchange (ETDEWEB)

Garcia, D.; Bruyere, V.I.E. [Gerencia Quimica, Comision Nacional de Energia Atomica, Centro Atomico Constituyentes, Av. Gral Paz 1499, 1650 San Martin, Prov. de Buenos Aires, Republica Argentina (Argentina); Instituto de Tecnologia, Prof. Jorge Sabato, Universidad Nacional de General San Martin, CNEA, CAC (Argentina); Bordoni, R.; Olmedo, A.M. [Gerencia Quimica, Comision Nacional de Energia Atomica, Centro Atomico Constituyentes, Av. Gral Paz 1499, 1650 San Martin, Prov. de Buenos Aires, Republica Argentina (Argentina); Morando, P.J., E-mail: morando@cnea.gov.ar [Gerencia Quimica, Comision Nacional de Energia Atomica, Centro Atomico Constituyentes, Av. Gral Paz 1499, 1650 San Martin, Prov. de Buenos Aires, Republica Argentina (Argentina); Instituto de Tecnologia, Prof. Jorge Sabato, Universidad Nacional de General San Martin, CNEA, CAC (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina)

2011-05-01

The ability of malonic acid as a dissolution agent toward synthetic Ni ferrite and Alloy 600 and 800 corrosion products was explored. Its performance in the dissolution kinetics of Ni ferrite powders was compared with the one of oxalic acid. Kinetic parameters were obtained and the dependency on external Fe(II) was modelled. Oxidized samples used in descaling tests were prepared by exposure of coupons of both alloys to lithiated aqueous solutions, under hydrothermal conditions and hydrogen overpressure, simulating PHWR conditions. Oxide layer morphology, the influence of exposure time to corrosive medium and LiOH concentration on its thickness were characterized. Descaling tests consisting on a two-stage method (a first oxidizing step with alkaline permanganate followed by a reducing step with oxalic or malonic acid were carried out). Results were compared to those obtained with a well known chemical cleaning formulation (APAC: Alkaline Permanganate Ammonium Citrate) used in decontamination of several reactors and loops and the competitiveness of malonic acid was demonstrated.

Electrochemical techniques to detect corrosion in concrete structures in nuclear installations - Technical note

International Nuclear Information System (INIS)

2002-01-01

The mechanism of corrosion in aqueous media is of electrochemical nature. This means that the oxidation of the metal is counterbalanced by the reduction of another substance in another region of the metallic surface. Therefore, zones (anodes and cathodes) with different electrochemical potential, develop. In the case of concrete the electrolyte is constituted by the pore solution, which is very alkaline. This pore solution is formed by mainly a mixture of KOH and NaOH presenting pH values ranging between 12.6-14. The solution is saturated in Ca(OH) 2 . Steel embedded in concrete is naturally protected by this high alkalinity and by the barrier effect of the cover itself. The two main causes of electrochemical corrosion are carbonation and the presence of chlorides. Carbonation usually induces a generalized corrosion while chloride will lead into pitting or localized attack. The corrosion can be easily recognized by the rust presence on the rebar and by the appearance of cracks running parallel to the rebars. The objective of this report is to describe the electrochemical non-destructive techniques that can be used in real size reinforced concrete structures to assess the corrosion condition of their reinforcement. These techniques can be used indistinctly in conventional civil engineering structures or in those of nuclear installations. Electrochemical techniques are used to detect electrochemical corrosion activity of metallic reinforcements. They cannot quantify stress corrosion cracking or hydrogen embrittlement although may give some qualitative information about them. The aims of their applications may be one of the following circumstances: 1. Quality control of new constructions; 2. Condition evaluation of existing structures for: - Identification of steel de-passivation, - Detecting corroding areas for rehabilitation purposes, - Calculation of residual load-bearing capacity of the structure, - Prediction of the damage evolution, - Determination of the

Alkaline Phosphatase, an Unconventional Immune Protein

Directory of Open Access Journals (Sweden)

Bethany A. Rader

2017-08-01

Full Text Available Recent years have seen an increase in the number of studies focusing on alkaline phosphatases (APs, revealing an expanding complexity of function of these enzymes. Of the four human AP (hAP proteins, most is known about tissue non-specific AP (TNAP and intestinal AP (IAP. This review highlights current understanding of TNAP and IAP in relation to human health and disease. TNAP plays a role in multiple processes, including bone mineralization, vitamin B6 metabolism, and neurogenesis, is the genetic cause of hypophosphatasia, influences inflammation through regulation of purinergic signaling, and has been implicated in Alzheimer’s disease. IAP regulates fatty acid absorption and has been implicated in the regulation of diet-induced obesity and metabolic syndrome. IAP and TNAP can dephosphorylate bacterial-derived lipopolysaccharide, and IAP has been identified as a potential regulator of the composition of the intestinal microbiome, an evolutionarily conserved function. Endogenous and recombinant bovine APs and recombinant hAPs are currently being explored for their potential as pharmacological agents to treat AP-associated diseases and mitigate multiple sources of inflammation. Continued research on these versatile proteins will undoubtedly provide insight into human pathophysiology, biochemistry, and the human holobiont.

Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

International Nuclear Information System (INIS)

Lobyntseva, Elena; Kallio, Tanja; Alexeyeva, Nadezda; Tammeveski, Kaido; Kontturi, Kyoesti

2007-01-01

The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O 2 -free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production. In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide

Electrosynthesis of Clozapine Drug Derivative via an EC Electrochemical Mechanism

Directory of Open Access Journals (Sweden)

Esmail Tammari

2017-12-01

Full Text Available The fact that oxidation, as one of the main routes of phase I metabolism of drugs, follows by conjugation reactions, and also formation of nitrenium ion as one of the clozapine oxidation products, directed us to investigate the oxidation of clozapine (CLZ in the presence of nucleophile. The oxidation of clozapine (CLZ has been studied on a glassy carbon electrode in the absence and presence of 2-thiobarbituric acid (TBA as nucleophile in aqueous medium by means of cyclic voltammetry and on the graphite rods in controlled-potential coulometry. Cyclic voltammetry studies were realized for CLZ in the pHs 1.0 to 8.0. Results indicate that the electrochemical behavior of CLZ depends on the pH. Based on the obtained electrochemical results, an ECE mechanism was proposed to explain the electrochemical oxidation of CLZ. The results revealed that oxidized CLZ participates in Michael type addition reaction with TBA and via an EC mechanism converts to the corresponding new dibenzodiazepin derivatives. The product has been characterized by IR, 1H NMR, 13C NMR and MS.

Development of anionic membranes produced by radiation-grafting for alkaline fuel cell applications

International Nuclear Information System (INIS)

Pereira, Clotilde Coppini

2017-01-01

Anion Exchange Membranes (AEMs) are a promising alternative to the development of more efficient electrolytes for alkaline fuel cells. In general, the AEMs are ionomeric membranes able to conduct hydroxide ions (OH - ) due to the quaternary ammonium groups, which confer high pH equivalent to the AEM. In order to develop alkaline membranes with high chemical and thermal stability, besides satisfactory ionic conductivity for alkaline fuel cells, membranes based on low density polyethylene (LDPE), ultrahigh weight molecular weight polyethylene (UHWHPE), poly(ethylene-co-tetrafluoroethylene) (PETFE) and poly(hexafluoropropylene-co-tetrafluoroethylene) (PFEP) previously irradiated by using 60 Co gamma and electron beam sources, have been synthesized by styrene-grafting, and functionalized with trimethylamine to introduced quaternary ammonium groups. The resulting membranes were characterized by electron paramagnetic resonance (EPR), Raman spectroscopy, thermogravimetry (TG) and electrochemical impedance spectroscopy (EIS). The determination of the grafting degree and water uptake were conducted by gravimetry and ion exchange capacity, by titration. The membranes synthesized with PELD and PEUHMW polymers pre-irradiated at 70 kGy and stored at low temperature (-70 deg C), up to 10 months, showed ionic conductivity results, in hydroxide form (OH - ), of 29 mS.cm -1 and 14 mS.cm -1 at 65 deg C, respectively. The PFEP polymers irradiated by the simultaneous process showed insufficient grating levels for the membrane synthesis, requiring more studies to improve the irradiation and grafting process. The styrene-grafted PETFE membranes, pre-irradiated at 70 kGy and stored at low temperature (-70 deg C), up to 10 months, showed ionic conductivity results, in hydroxide form (OH - ), of 90 mS.cm -1 to 165 mS.cm -1 , in the temperature range 30 to 60 deg C. Such results have demonstrated that LDPE, UHMWPE and PETFE based AEMs are promising electrolytes for alkaline fuel cell

Posttranslational heterogeneity of bone alkaline phosphatase in metabolic bone disease.

Science.gov (United States)

Langlois, M R; Delanghe, J R; Kaufman, J M; De Buyzere, M L; Van Hoecke, M J; Leroux-Roels, G G

1994-09-01

Bone alkaline phosphatase is a marker of osteoblast activity. In order to study the posttranscriptional modification (glycosylation) of bone alkaline phosphatase in bone disease, we investigated the relationship between mass and catalytic activity of bone alkaline phosphatase in patients with osteoporosis and hyperthyroidism. Serum bone alkaline phosphatase activity was measured after lectin precipitation using the Iso-ALP test kit. Mass concentration of bone alkaline phosphatase was determined with an immunoradiometric assay (Tandem-R Ostase). In general, serum bone alkaline phosphatase mass and activity concentration correlated well. The activity : mass ratio of bone alkaline phosphatase was low in hyperthyroidism. Activation energy of the reaction catalysed by bone alkaline phosphatase was high in osteoporosis and in hyperthyroidism. Experiments with neuraminidase digestion further demonstrated that the thermodynamic heterogeneity of bone alkaline phosphatase can be explained by a different glycosylation of the enzyme.

Redox exchange induced MnO2 nanoparticle enrichment in poly(3,4-ethylenedioxythiophene) nanowires for electrochemical energy storage.

Science.gov (United States)

Liu, Ran; Duay, Jonathon; Lee, Sang Bok

2010-07-27

MnO2 nanoparticle enriched poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires are fabricated by simply soaking the PEDOT nanowires in potassium permanganate (KMnO4) solution. The structures of these MnO2 nanoparticle enriched PEDOT nanowires are characterized by SEM and TEM, which show that the MnO2 nanoparticles have uniform sizes and are finely dispersed in the PEDOT matrix. The chemical constituents and bonding of these composite nanowires are characterized by energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and infrared spectroscopy, which indicate that the formation and dispersion of these MnO2 nanoparticles into the nanoscale pores of the PEDOT nanowires are most likely triggered by the reduction of KMnO4 via the redox exchange of permanganate ions with the functional group on PEDOT. Varying the concentrations of KMnO4 and the reaction time controls the loading amount and size of the MnO2 nanoparticles. Cyclic voltammetry and galvanostatic charge-discharge are used to characterize the electrochemical properties of these MnO2 nanoparticle loaded PEDOT nanowires. Due to their extremely high exposed surface area with nanosizes, the pristine MnO2 nanoparticles in these MnO2 nanoparticle enriched PEDOT nanowires show very high specific capacitance (410 F/g) as the supercapacitor electrode materials as well as high Li+ storage capacity (300 mAh/g) as cathode materials of Li ion battery, which boost the energy storage capacity of PEDOT nanowires to 4 times without causing excessive volume expansion in the polymer. The highly conductive and porous PEDOT matrix facilitates fast charge/discharge of the MnO2 nanoparticles and prevents them from agglomerating. These synergic properties enable the MnO2 nanoparticle enriched PEDOT nanowires to be promising electrode materials for supercapacitors and lithium ion batteries.

Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation

International Nuclear Information System (INIS)

Geraldes, Adriana Napoleão; Furtunato da Silva, Dionisio; Pino, Eddy Segura; Martins da Silva, Júlio César; Brambilla de Souza, Rodrigo Fernando; Hammer, Peter; Spinacé, Estevam Vitório; Neto, Almir Oliveira; Linardi, Marcelo; Coelho dos Santos, Mauro

2013-01-01

Carbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd:Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3–5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd:Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown that the mechanism for ethanol electro-oxidation is dependent on catalyst composition, leading to different reaction products, such as acetaldehyde and acetate, depending on the number of electrons transferred. Experiments on a single ADEFC were conducted between 50 and 90 °C, and the best performance of 44 mW cm −2 in 2.0 mol L −1 ethanol was obtained at 85 °C for the Pd:Au 90:10 catalysts. This superior performance is most likely associated with enhancement of ethanol adsorption on Pd, oxidation of the intermediates, the presence of gold oxide-hydroxyl species, low mean particle diameters and better distribution of particles on the support

MODELING AN ION EXCHANGE PROCESS FOR CESIUM REMOVAL FROM ALKALINE RADIOACTIVE WASTE SOLUTIONS

International Nuclear Information System (INIS)

Smith, F.; Hamm, Luther; Aleman, Sebastian; Michael, Johnston

2008-01-01

The performance of spherical Resorcinol-Formaldehyde ion-exchange resin for the removal of cesium from alkaline radioactive waste solutions has been investigated through computer modeling. Cesium adsorption isotherms were obtained by fitting experimental data using a thermodynamic framework. Results show that ion-exchange is an efficient method for cesium removal from highly alkaline radioactive waste solutions. On average, two 1300 liter columns operating in series are able to treat 690,000 liters of waste with an initial cesium concentration of 0.09 mM in 11 days achieving a decontamination factor of over 50,000. The study also tested the sensitivity of ion-exchange column performance to variations in flow rate, temperature and column dimensions. Modeling results can be used to optimize design of the ion exchange system

Transuranium removal from Hanford high level waste simulants using sodium permanganate and calcium

International Nuclear Information System (INIS)

Wilmarth, W.R.; Rosencrance, S.W.; Nash, C.A.; Fonduer, F.F.; Di Pirete, D.P.; Di Prete, C.C.

2000-01-01

Plutonium and americium are present in the Hanford high level liquid waste complexant concentrate (CC) due to the presence of complexing agents including di-(2-ethylhexyl) phosphoric acid (D 2 EHPA), tributylphosphate (TBP), hydroxyethylene diamine triacetic acid (HEDTA), ethylene diamine tetraacetic acid (EDTA), citric acid, glycolic acid, and sodium gluconate. The transuranic concentrations approach 600 nCi/g and require processing prior to encapsulation into low activity glass. BNFL's (British Nuclear Fuels Limited's) original process was a ferric co-precipitation method based on earlier investigations by Herting and Orth, et al. Furthermore, flocculation and precipitation are widely used for clarification in municipal water treatment. Co-precipitation of Np, Am, and Pu with ferric hydroxide is also used within an analytical method for the sum of those analytes. Tests to evaluate BNFL's original precipitation process indicated the measured decontamination factors (DFs) and filter fluxes were too low. Therefore, an evaluation of alternative precipitation agents to replace ferric ion was undertaken. Agents tested included various transition metals, lanthanide elements, uranium species, calcium, strontium, and permanganate

NO/sub x/ removal facility: MON process

Energy Technology Data Exchange (ETDEWEB)

Fukuda, Y

1974-05-01

A newly developed process for nitrogen oxides removal is described. The MON process, named for Mitsubishi Kizoku, Okabe of Tohoku Univ., and Nippon Kagaku, uses potassium permanganate as an oxidizing agent. Potassium permanganate in alkaline solution converts nitric oxide into nitrate and nitrogen dioxide into nitric acid. The resulting MnO/sub 2/ is easily filtered and recovered as material for the manufacturing of KMnO/sub 4/. Contrary to the conventional methods, the NO/sub x/ conversion rate increases with increasing temperature. Test results at a pilot plant showed that NO/sub x/ was reduced from 570 ppM (nitric oxide 520 ppM) to 27 ppM (mostly NO) at 97 to 98 percent conversion. Another advantage of the process is that other acidic gases such as sulfur dioxide are also removed.

Graphene-cobaltite-Pd hybrid materials for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells.

Science.gov (United States)

Sharma, Chandra Shekhar; Awasthi, Rahul; Singh, Ravindra Nath; Sinha, Akhoury Sudhir Kumar

2013-12-14

Hybrid materials comprising of Pd, MCo2O4 (where M = Mn, Co or Ni) and graphene have been prepared for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells. Structural and electrochemical characterizations were carried out using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry and cyclic, CO stripping, and linear sweep voltammetries. The study revealed that all the three hybrid materials are active for both methanol oxidation (MOR) and oxygen reduction (ORR) reactions in 1 M KOH. However, the Pd-MnCo2O4/GNS hybrid electrode exhibited the greatest MOR and ORR activities. This active hybrid electrode has also outstanding stability under both MOR and ORR conditions, while Pt- and other Pd-based catalysts undergo degradation under similar experimental conditions. The Pd-MnCo2O4/GNS hybrid catalyst exhibited superior ORR activity and stability compared to even Pt in alkaline solutions.

An alkaline approach to treating cooling towers for control of Legionella pneumophila.

Science.gov (United States)

States, S J; Conley, L F; Towner, S G; Wolford, R S; Stephenson, T E; McNamara, A M; Wadowsky, R M; Yee, R B

1987-08-01

Earlier field and laboratory studies have shown that Legionella species survive and multiply in the pH range 5.5 to 9.2. Additionally, the technical feasibility of operating cooling towers at elevated alkalinities and pH has previously been documented by published guidelines. The guidelines indicate that these conditions facilitate corrosion control and favor chlorine persistence which enhances the effectiveness of continuous chlorination in biofouling control. This information suggests that control of Legionella species in cooling towers can be accomplished by operating the towers under alkaline conditions. To test this possibility, we collected water samples over a period of months from a hospital cooling tower. The samples were analyzed for a variety of chemical parameters. Subsamples were pasteurized and inoculated with non-agar-passaged Legionella pneumophila which had been maintained in tap water. Correlation of subsequent Legionella growth with corresponding pH and alkalinity values revealed statistically significant inverse associations. These data support the hypothesis that operating cooling towers outside of the optimal conditions for Legionella growth (e.g., at elevated alkalinities and a pH greater than 9) may be a useful approach to controlling growth in this habitat.

The development of a state-of-the-art experimental setup demonstrated by the investigation of fuel cell reactions in alkaline electrolyte

Energy Technology Data Exchange (ETDEWEB)

Wiberg, Gustav Karl Henrik

2010-10-04

, shifting the coverage away from equilibrium and driving the reduction of the PtOH surface species to H{sub 2}O freeing a Pt site. It was not, however, possible to distinguish between the two possible ORR mechanisms, either associative or dissociative using this technique because the reduction and oxidation of HO{sup -}{sub 2} on PC Pt is always diffusion limited. In the second study, a methodology was developed in order to determine the ORR activity of a non-platinum catalyst using the thin-film RDE technique. Here, a Ag nanoparticle catalyst deposited onto a glassy carbon substrate was first characterised in terms of the NECAS using the upd of Pb. The catalyst utilisation was assessed and verified by scaling the NECAS and ORR activity with catalyst loading up to values of 200 {mu}g cm{sup -2}. Once an appropriate loading was established, both the TOF, mass and specific activity of Ag nanoparticles towards the ORR in alkaline solution could be precisely determined at FC relevant potentials. No difference was observed between the ORR activity of the NP Ag catalyst and model PC Ag electrode. Furthermore, the ORR TOF on Ag at 0.9 V{sub RHE} (0.1 Hz) is approximately one order of magnitude less than on PC Pt. Finally, a set of methodology guidelines were recommended for future characterisation of both Pt and non-Pt nanoparticle catalysts, in order to facilitate meaningful activity comparisons between different types of catalysts. To summarise, the state-of-the-art electrochemical setup developed in this work allows precise study and characterisation of various electrodes using a variety of EC techniques under controlled experimental conditions. Its effectiveness was demonstrated by the experimental elucidation of the role of PtOH species on the measured catalytic activity of the ORR. Finally, a methodology to characterise the catalytic activity of a non-Pt catalyst towards the ORR was developed. (orig.)

Alkaline sorbent injection for mercury control

Science.gov (United States)

Madden, Deborah A.; Holmes, Michael J.

2002-01-01

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

International Nuclear Information System (INIS)

Day, S D; Wong, F G; Gordon, S R; Wong, L L; Rebak, R B

2006-01-01

Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

Electrochemical Testing of Gas Tungsten ARC Welded and Reduced Pressure Electron Beam Welded Alloy 22

International Nuclear Information System (INIS)

S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak

2006-01-01

Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

Alkaline resistant ceramics; Alkalimotstaandskraftiga keramer

Energy Technology Data Exchange (ETDEWEB)

Westberg, Stig-Bjoern [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

2001-02-01

Despite durability in several environments, ceramics and refractories can not endure alkaline environments at high temperature. An example of such an environment is when burning biofuel in modern heat and power plants in which the demand for increasing efficiency results in higher combustion temperatures and content of alkaline substances in the flue gas. Some experiences of these environments has been gained from such vastly different equipment as regenerator chambers in the glass industry and MHD-generators. The grains of a ceramic material are usually bonded together by a glassy phase which despite it frequently being a minor constituent render the materials properties and limits its use at elevated temperature. The damage is usually caused by alkaline containing low-melting phases and the decrease of the viscosity of the bonding glass phase which is caused by the alkaline. The surfaces which are exposed to the flue gas in a modern power plant are not only exposed to the high temperature but also a corroding and eroding, particle containing, gas flow of high velocity. The use of conventional refractory products is limited to 1300-1350 deg C. Higher strength and fracture toughness as well as durability against gases, slag and melts at temperatures exceeding 1700 deg C are expected of the materials of the future. Continuous transport of corrosive compounds to the surface and corrosion products from the surface as well as a suitable environment for the corrosion to occur in are prerequisites for extensive corrosion to come about. The highest corrosion rate is therefore found in a temperature interval between the dew point and the melting point of the alkaline-constituent containing compound. It is therefore important that the corrosion resistance is sufficient in the environment in which alkaline containing melts or slag may appear. In environments such as these, even under normal circumstances durable ceramics, such as alumina and silicon carbide, are attacked

Corrosion monitoring in a straw-fired power plant using an electrochemical noise probe

DEFF Research Database (Denmark)

Cappeln, Frederik Vilhelm; Bjerrum, Niels; Petrushina, Irina

2007-01-01

Electrochemical Noise Measurements have been carried out in situ in a straw-fired power plant using an experimental probe constructed from alumina and AlSl 347 steel. Based on a framework of controlled laboratory experiments it has been found that electrochemical noise has the unique ability...... to provide in-situ monitoring of intergranular corrosion in progress. The probe had a lifetime of two months. It was shown that down-time corrosion in the boiler was negligible. Electrochemical noise data indicated that metal temperatures around 590 degrees C should be avoided as the intergranular corrosion...

Use of potassium permanganate integrated chemical-biological treatment schemes of wastewaters from agricultural industry; Aplicacion de permanganato potasico en sistemas de tratamiento integrado quimico-biologico en las aguas residuales de la industria agricola

Energy Technology Data Exchange (ETDEWEB)

Medialdea, J. M.; Arnaiz, M. C.; Isac, L.; Ruiz, C.; Valentin, R.; Martinez, M. F.; Garcia, S.; Lebrato, J. [Universidad de Sevilla (Spain); Cuenca, I.

2000-07-01

Present study assesses the applicability of a treatment scheme based on the combination of anaerobic biological digestion and chemical oxidation by potassium permanganate, in the purification of winery wastewaters. Biological digestion, performed using an experimental 1-liter reactor that operated discontinuously with completely mixed input and a mesophilic regime (35 degree centigree), removed 65% and 78% of water COD and BOD, and contributed 82,27% to the system global efficiency. Further chemical oxidation of effluent by Aquox -potassium permanganate eliminated 40% of residual COD, although contributed only 17,73% to global purification efficiency. However, effluent chemical oxidation at a dosage of 35 mg KMnO{sub 4}/L significantly increased effluent biodegradability. Results demonstrated the feasibility of analyzed working scheme and provide a positive valuation on the use of KMnO{sub 4} in the treatment of winery wastewaters. (Author) 24 refs.

Electrodeposition synthesis and electrochemical properties of nanostructured γ-MnO 2 films

Science.gov (United States)

Chou, Shulei; Cheng, Fangyi; Chen, Jun

The thin films of carambola-like γ-MnO 2 nanoflakes with about 20 nm in thickness and at least 200 nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO 2 nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO 2 batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO 2 nanoflake films displayed high potential plateau (around 1.0 V versus Zn) in primary Zn/MnO 2 batteries at the discharge current density of 500 mA g -1 and high specific capacitance of 240 F g -1 at the current density of 1 mA cm -2. This indicated the potential application of carambola-like γ-MnO 2 nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO 2 was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films.

Effectiveness of copper sulfate, potassium permanganate, and peracetic acid to reduce mortality and infestation of Ichthyobodo nector in channel catfish Ictalurus punctatus (Rafinesque 1818)

Science.gov (United States)

Ichthyobodo necator is a single celled bi-flagellate parasite, and in high density can causes significant mortality in young fish. Copper sulfate (CuSO4), potassium permanganate (KMnO4) and peracetic acid (PAA) were evaluated for effectiveness against ichthyobodosis. Treatments were: untreated con...

Sample preparation in alkaline media

International Nuclear Information System (INIS)

Nobrega, Joaquim A.; Santos, Mirian C.; Sousa, Rafael A. de; Cadore, Solange; Barnes, Ramon M.; Tatro, Mark

2006-01-01

The use of tetramethylammonium hydroxide, tertiary amines and strongly alkaline reagents for sample treatment involving extraction and digestion procedures is discussed in this review. The preparation of slurries is also discussed. Based on literature data, alkaline media offer a good alternative for sample preparation involving an appreciable group of analytes in different types of samples. These reagents are also successfully employed in tailored speciation procedures wherein there is a critical dependence on maintenance of chemical forms. The effects of these reagents on measurements performed using spectroanalytical techniques are discussed. Several undesirable effects on transport and atomization processes necessitate use of the method of standard additions to obtain accurate results. It is also evident that alkaline media can improve the performance of techniques such as inductively coupled plasma mass spectrometry and accessories, such as autosamplers coupled to graphite furnace atomic absorption spectrometers