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Karel Bouzek - One of the best experts on this subject based on the ideXlab platform.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part iii anodic Dissolution kinetics of a white cast iron Anode rich in iron carbide
    Journal of Applied Electrochemistry, 2012
    Co-Authors: Z Macova, Karel Bouzek
    Abstract:

    The anolyte composition and process temperature could improve the kinetics of iron Anode Dissolution and subsequent ferrate(VI) production significantly. This also holds for the Anode composition. Following pure iron and silicon-rich steel (SRS), white cast iron (WCI) was the last representative of Anode material tested that is typically used to produce ferrate(VI). Using anolytes 14 M NaOH, 14 M KOH, and mixtures thereof, the systems were studied by potentiodynamic methods, electrochemical impedance spectroscopy, and batch electrolysis experiments. Additionally, metallographic analysis of the material was performed. The Dissolution kinetics increases with increasing temperature and also, at 60 °C, with increasing K+ content in the anolyte, but less progressively than in the case of SRS. Similar to SRS, WCI also easily dissolves into ferrate(VI) even at 20 °C in pure NaOH, thus indicating the inferior protective properties of oxo-hydroxide surface layers. In general, a maximum current efficiency of approx. 60 % was obtained at 60 °C in pure KOH solution. The authors conclude that, at 60 °C, the high efficiency of the synthesis is caused by the low protective properties of the oxo-hydroxide surface layer caused by the preferential Dissolution of cementite and at the same time by the precipitation of the potassium salt of the product in the electrolyte immediately after its formation. This minimizes the effect of its decomposition.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part ii anodic Dissolution kinetics of a steel Anode rich in silicon
    Journal of Applied Electrochemistry, 2011
    Co-Authors: Z Macova, Karel Bouzek
    Abstract:

    The anolyte composition and process temperature could improve the kinetics of iron Anode Dissolution and subsequent ferrate(VI) production significantly. This also holds for the Anode composition. Silicon-rich steel (SRS) was employed as the Anode material to produce ferrate(VI), and the characteristics observed were compared with those of the pure iron Anode obtained during our previous study. Using anolytes 14 M NaOH, 14 M KOH and mixtures thereof, the systems were studied by means of potentiodynamic methods, electrochemical impedance spectroscopy and batch electrolysis experiments. In addition, scanning electron microscopy and metallographic images of the material surface were taken to identify changes in the phase composition of the material, caused by anodic polarization in strongly alkaline solutions. The Dissolution kinetics increases with increasing temperature and, at 60 °C, also with increasing K+ content in the anolyte. Compared to iron, SRS easily dissolves into ferrate(VI), even at 20 °C in pure NaOH, indicating the lower inferior protective properties of oxy-hydroxide surface layers. The current efficiency achieved was almost 55% under these conditions. In the other anolytes, a maximum current efficiency of ca. 40% was obtained at 60 °C. The authors conclude that, at 60 °C, the efficiency is lowered by intensified oxygen evolution. This causes intensive solution convection, disturbing the surface conditions supporting ferrate(VI) formation.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part i anodic Dissolution kinetics of pure iron
    Journal of Applied Electrochemistry, 2010
    Co-Authors: Z Macova, Karel Bouzek, Virender K. Sharma
    Abstract:

    The influence of anolyte composition and temperature on the Anode Dissolution kinetics of pure iron and subsequent ferrate(VI) production was studied by means of potentiodynamic voltammetry and electrochemical impedance spectroscopy. The results obtained were verified by batch electrolyses. Pure NaOH, KOH, and mixtures thereof were used as an anolyte. The motivation for this study is to understand in more detail the electrolysis process at which ferrate(VI) is electrochemically produced in situ in the solid form which is more suitable for practical utilization. A significant impact of the anolyte composition on the system behavior was indicated. It is related to the solubility of the Anode Dissolution products in the anolyte. It was concluded that the fast reaction kinetics in the transpassive potential region is connected with a deterioration of the ferrate(VI) synthesis efficiency. This is explained by the kinetic enhancement corresponding to the intensification of oxygen evolution as a parasitic reaction.

  • The role of the electrode and electrolyte composition in the Anode Dissolution kinetics: Comparison of the Ferrate(VI) synthesis in the solutions of NaOH and KOH of various ratio
    ACS Symposium Series, 2008
    Co-Authors: Z Macova, Karel Bouzek, Virender K. Sharma
    Abstract:

    This study deals with the influence of the Anode material and the electrolyte composition on the kinetics of the electrode Dissolution and on the Ferrate(VI) formation. The cast iron rich in iron carbide and the silicon rich steel are compared as perspective materials that provide the highest current efficiency of the electrochemical synthesis process. Pure NaOH, KOH solutions and their mixtures were used as an electrolyte. Electrochemical impedance spectroscopy was used to quantify the influence of the individual parameters on the Anode Dissolution kinetics. The results were compared with the pure iron study results, in order to assess impact of the individual Anode material components on the Anode's behavior. The theory, derived on the basis of the electrochemical impedance spectroscopy and cyclic voltammetry data, was confirmed by the batch electrolysis experiments.

Z Macova - One of the best experts on this subject based on the ideXlab platform.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part iii anodic Dissolution kinetics of a white cast iron Anode rich in iron carbide
    Journal of Applied Electrochemistry, 2012
    Co-Authors: Z Macova, Karel Bouzek
    Abstract:

    The anolyte composition and process temperature could improve the kinetics of iron Anode Dissolution and subsequent ferrate(VI) production significantly. This also holds for the Anode composition. Following pure iron and silicon-rich steel (SRS), white cast iron (WCI) was the last representative of Anode material tested that is typically used to produce ferrate(VI). Using anolytes 14 M NaOH, 14 M KOH, and mixtures thereof, the systems were studied by potentiodynamic methods, electrochemical impedance spectroscopy, and batch electrolysis experiments. Additionally, metallographic analysis of the material was performed. The Dissolution kinetics increases with increasing temperature and also, at 60 °C, with increasing K+ content in the anolyte, but less progressively than in the case of SRS. Similar to SRS, WCI also easily dissolves into ferrate(VI) even at 20 °C in pure NaOH, thus indicating the inferior protective properties of oxo-hydroxide surface layers. In general, a maximum current efficiency of approx. 60 % was obtained at 60 °C in pure KOH solution. The authors conclude that, at 60 °C, the high efficiency of the synthesis is caused by the low protective properties of the oxo-hydroxide surface layer caused by the preferential Dissolution of cementite and at the same time by the precipitation of the potassium salt of the product in the electrolyte immediately after its formation. This minimizes the effect of its decomposition.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part ii anodic Dissolution kinetics of a steel Anode rich in silicon
    Journal of Applied Electrochemistry, 2011
    Co-Authors: Z Macova, Karel Bouzek
    Abstract:

    The anolyte composition and process temperature could improve the kinetics of iron Anode Dissolution and subsequent ferrate(VI) production significantly. This also holds for the Anode composition. Silicon-rich steel (SRS) was employed as the Anode material to produce ferrate(VI), and the characteristics observed were compared with those of the pure iron Anode obtained during our previous study. Using anolytes 14 M NaOH, 14 M KOH and mixtures thereof, the systems were studied by means of potentiodynamic methods, electrochemical impedance spectroscopy and batch electrolysis experiments. In addition, scanning electron microscopy and metallographic images of the material surface were taken to identify changes in the phase composition of the material, caused by anodic polarization in strongly alkaline solutions. The Dissolution kinetics increases with increasing temperature and, at 60 °C, also with increasing K+ content in the anolyte. Compared to iron, SRS easily dissolves into ferrate(VI), even at 20 °C in pure NaOH, indicating the lower inferior protective properties of oxy-hydroxide surface layers. The current efficiency achieved was almost 55% under these conditions. In the other anolytes, a maximum current efficiency of ca. 40% was obtained at 60 °C. The authors conclude that, at 60 °C, the efficiency is lowered by intensified oxygen evolution. This causes intensive solution convection, disturbing the surface conditions supporting ferrate(VI) formation.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part i anodic Dissolution kinetics of pure iron
    Journal of Applied Electrochemistry, 2010
    Co-Authors: Z Macova, Karel Bouzek, Virender K. Sharma
    Abstract:

    The influence of anolyte composition and temperature on the Anode Dissolution kinetics of pure iron and subsequent ferrate(VI) production was studied by means of potentiodynamic voltammetry and electrochemical impedance spectroscopy. The results obtained were verified by batch electrolyses. Pure NaOH, KOH, and mixtures thereof were used as an anolyte. The motivation for this study is to understand in more detail the electrolysis process at which ferrate(VI) is electrochemically produced in situ in the solid form which is more suitable for practical utilization. A significant impact of the anolyte composition on the system behavior was indicated. It is related to the solubility of the Anode Dissolution products in the anolyte. It was concluded that the fast reaction kinetics in the transpassive potential region is connected with a deterioration of the ferrate(VI) synthesis efficiency. This is explained by the kinetic enhancement corresponding to the intensification of oxygen evolution as a parasitic reaction.

  • The role of the electrode and electrolyte composition in the Anode Dissolution kinetics: Comparison of the Ferrate(VI) synthesis in the solutions of NaOH and KOH of various ratio
    ACS Symposium Series, 2008
    Co-Authors: Z Macova, Karel Bouzek, Virender K. Sharma
    Abstract:

    This study deals with the influence of the Anode material and the electrolyte composition on the kinetics of the electrode Dissolution and on the Ferrate(VI) formation. The cast iron rich in iron carbide and the silicon rich steel are compared as perspective materials that provide the highest current efficiency of the electrochemical synthesis process. Pure NaOH, KOH solutions and their mixtures were used as an electrolyte. Electrochemical impedance spectroscopy was used to quantify the influence of the individual parameters on the Anode Dissolution kinetics. The results were compared with the pure iron study results, in order to assess impact of the individual Anode material components on the Anode's behavior. The theory, derived on the basis of the electrochemical impedance spectroscopy and cyclic voltammetry data, was confirmed by the batch electrolysis experiments.

Virender K. Sharma - One of the best experts on this subject based on the ideXlab platform.

  • the influence of electrolyte composition on electrochemical ferrate vi synthesis part i anodic Dissolution kinetics of pure iron
    Journal of Applied Electrochemistry, 2010
    Co-Authors: Z Macova, Karel Bouzek, Virender K. Sharma
    Abstract:

    The influence of anolyte composition and temperature on the Anode Dissolution kinetics of pure iron and subsequent ferrate(VI) production was studied by means of potentiodynamic voltammetry and electrochemical impedance spectroscopy. The results obtained were verified by batch electrolyses. Pure NaOH, KOH, and mixtures thereof were used as an anolyte. The motivation for this study is to understand in more detail the electrolysis process at which ferrate(VI) is electrochemically produced in situ in the solid form which is more suitable for practical utilization. A significant impact of the anolyte composition on the system behavior was indicated. It is related to the solubility of the Anode Dissolution products in the anolyte. It was concluded that the fast reaction kinetics in the transpassive potential region is connected with a deterioration of the ferrate(VI) synthesis efficiency. This is explained by the kinetic enhancement corresponding to the intensification of oxygen evolution as a parasitic reaction.

  • The role of the electrode and electrolyte composition in the Anode Dissolution kinetics: Comparison of the Ferrate(VI) synthesis in the solutions of NaOH and KOH of various ratio
    ACS Symposium Series, 2008
    Co-Authors: Z Macova, Karel Bouzek, Virender K. Sharma
    Abstract:

    This study deals with the influence of the Anode material and the electrolyte composition on the kinetics of the electrode Dissolution and on the Ferrate(VI) formation. The cast iron rich in iron carbide and the silicon rich steel are compared as perspective materials that provide the highest current efficiency of the electrochemical synthesis process. Pure NaOH, KOH solutions and their mixtures were used as an electrolyte. Electrochemical impedance spectroscopy was used to quantify the influence of the individual parameters on the Anode Dissolution kinetics. The results were compared with the pure iron study results, in order to assess impact of the individual Anode material components on the Anode's behavior. The theory, derived on the basis of the electrochemical impedance spectroscopy and cyclic voltammetry data, was confirmed by the batch electrolysis experiments.

Giovanni Esposito - One of the best experts on this subject based on the ideXlab platform.

  • application of an electrochemical treatment for edds soil washing solution regeneration and reuse in a multi step soil washing process case of a cu contaminated soil
    Journal of Environmental Management, 2015
    Co-Authors: Alberto Ferraro, Eric D Van Hullebusch, David Huguenot, Massimiliano Fabbricino, Giovanni Esposito
    Abstract:

    Abstract Soil washing is an extensively used process for remediation of heavy metals contaminated soils. However the amount of fresh washing solution to be used represents a significant economical drawback of this process. This paper investigates the application of an electrochemical process (Fe/Fe electrodes couple) for the regeneration of a spent EDDS solution, containing Cu and major competitor cations (Ca, Fe, Mg, and Mn). The effect of current density, pH and conductivity of the washing solution on the recovery process performances was investigated. Current density showed the highest influence on Cu, Mg and Mn removal yields. Maximum removal yields reached 99% for Cu, 77% for Mn and 49% for Mg. No influence of the investigated parameters on Ca removal was observed, while an increase of Fe concentration due to Anode Dissolution occurred. Characterization of sludge produced from the 2 h electrochemical test (5 mA cm −2 , pH = 8, 8 mS cm −1 ) displayed concentrations of 2.8 g kg −1 for Ca, 0.4 g kg −1 for Cu, 535.6 g kg −1 for Fe, 2.6 g kg −1 for Mg. TCLP tests at pH 2.88 and 4.93 showed a low leaching percentage (Ca, 10–21%; Cu, 6–12%; Fe, 0.22% Mg, 27–36%). Multi-washing tests were carried out to assess the decrease of the chelating ability of the regenerated washing solution and the Cu extraction efficiency.

S P Arkhipov - One of the best experts on this subject based on the ideXlab platform.

  • Anode Dissolution of ternary pb sb bi alloys and reduction of lead in the kcl pbc 2 melt
    Journal of The Iranian Chemical Society, 2019
    Co-Authors: P A Arkhipov, A S Kholkina, Yu P Zaykov, S P Arkhipov
    Abstract:

    The influence of bismuth, antimony and lead concentrations on the Pb–Sb–Bi alloys Anode Dissolution in the KCl–PbCl2 equimolar melt was studied. The lead Dissolution process, which starts at the potentials close to the equilibrium ones, was found to be the basic process up to the certain potentials. A number of electrons, which take part in the cathode reactions, was determined. The diffusion layer thickness in the liquid metal Anode was estimated according to the values of metal-limiting diffusion current. The electrolytic reduction of lead from the Pb–Sb–Bi ternary alloys was performed.