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F C Walsh - One of the best experts on this subject based on the ideXlab platform.

  • corrosion of the zinc negative electrode of zinc cerium hybrid redox flow batteries in Methanesulfonic Acid
    Journal of Applied Electrochemistry, 2014
    Co-Authors: C Poncedeleon, Puiki Leung, F J Recio, P Herrasti, F C Walsh
    Abstract:

    Corrosion of zinc in aqueous Methanesulfonic Acid has been evaluated over a wide range of concentrations of Acid (0.5–5 mol dm−3), dissolved zinc (0.5–2 mol dm−3), and electrolyte temperature (22–50 °C). The corrosion rate of zinc, in terms of weight loss and the volume of hydrogen evolved, varied with time and it was found to be highly dependent on the surface state and electrolyte conditions. With an initial active layer of zinc present, the corrosion rate rapidly increased following a decline when the proton concentration in the solution decreased to ca. 0.56 mol dm−3. Organic and inorganic inhibitors were added to the electrolyte to suppress the zinc corrosion in 1 mol dm−3 Methanesulfonic Acid. The strong adsorption and blocking effects of cationic organic adsorption inhibitors, such as cetyltrimethyl ammonium bromide and butyltriphenyl phosphonium chloride, led to a significant decrease in zinc corrosion over a 10 h immersion period. With the addition of indium and lead ions inhibitors, the zinc surface showed less activity. Zinc corrosion continued to a smaller extent in the presence of these metallic inhibitors during the first few hours, but the metallic layer of the inhibitors did not cover the surface completely resulting in continued hydrogen evolution and making the inhibitors less effective at longer times.

  • zinc deposition and dissolution in Methanesulfonic Acid onto a carbon composite electrode as the negative electrode reactions in a hybrid redox flow battery
    Electrochimica Acta, 2011
    Co-Authors: Puiki Leung, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Electrodeposition and dissolution of zinc in Methanesulfonic Acid were studied as the negative electrode reactions in a hybrid redox flow battery. Cyclic voltammetry at a rotating disk electrode was used to characterize the electrochemistry and the effect of process conditions on the deposition and dissolution rate of zinc in aqueous Methanesulfonic Acid. At a sufficiently high current density, the deposition process became a mass transport controlled reaction. The diffusion coefficient of Zn2+ ions was 7.5 × 10−6 cm2 s−1. The performance of the zinc negative electrode in a parallel plate flow cell was also studied as a function of Zn2+ ion concentration, Methanesulfonic Acid concentration, current density, electrolyte flow rate, operating temperature and the addition of electrolytic additives, including potassium sodium tartarate, tetrabutylammonium hydroxide, and indium oxide. The current-, voltage- and energy efficiencies of the zinc-half cell reaction and the morphologies of the zinc deposits are also discussed. The energy efficiency improved from 62% in the absence of additives to 73% upon the addition of 2 × 10−3 mol dm−3 of indium oxide as a hydrogen suppressant. In aqueous Methanesulfonic Acid with or without additives, there was no significant dendrite formation after zinc electrodeposition for 4 h at 50 mA cm−2.

  • ce iii ce iv in Methanesulfonic Acid as the positive half cell of a redox flow battery
    Electrochimica Acta, 2011
    Co-Authors: Puiki Leung, Ponce C De Leon, F C Walsh
    Abstract:

    The characteristics of the Ce(III)/Ce(IV) redox couple in Methanesulfonic Acid were studied at a platinum disk electrode (0.125 cm2) over a wide range of electrolyte compositions and temperatures: cerium (III) methanesulfonate (0.1–1.2 mol dm−3), Methanesulfonic Acid (0.1–5.0 mol dm−3) and electrolyte temperatures (295–333 K). The cyclic voltammetry experiments indicated that the diffusion coefficient of Ce(III) ions was 0.5 × 10−6 cm2 s−1 and that the electrochemical kinetics for the oxidation of Ce(III) and the reduction of Ce(IV) was slow. The reversibility of the redox reaction depended on the electrolyte composition and improved at higher electrolyte temperatures. At higher Methanesulfonic Acid concentrations, the degree of oxygen evolution decreased by up to 50% when the Acid concentration increased from 2 to 5 mol dm−3. The oxidation of Ce(III) and reduction of Ce(IV) were also investigated during a constant current batch electrolysis in a parallel plate zinc–cerium flow cell with a 3-dimensional platinised titanium mesh electrode. The current efficiencies over 4.5 h of the process Ce(III) to Ce(IV) and 3.3 h electrolysis of the reverse reaction Ce(IV) to Ce(III) were 94.0 and 97.6%, respectively. With a 2-dimensional, planar platinised titanium electrode (9 cm2 area), the redox reaction of the Ce(III)/Ce(IV) system was under mass-transport control, while the reaction on the 3-dimensional mesh electrode was initially under charge-transfer control but became mass-transport controlled after 2.5–3 h of electrolysis. The effect of the side reactions (hydrogen and oxygen evolution) on the current efficiencies and the conversion of Ce(III) and Ce(IV) are discussed.

  • the characterisation of pbo2 coated electrodes prepared from aqueous Methanesulfonic Acid under controlled deposition conditions
    Electrochimica Acta, 2010
    Co-Authors: Ignasi Sires, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Abstract A series of PbO2 coatings on planar carbon substrates has been prepared by anodic deposition in aqueous Methanesulfonic Acid (MSA) under galvanostatic conditions. The effect of four experimental parameters, i.e., lead(II) methanesulfonate and MSA concentrations, current density, and temperature was analysed. Surface characterisation by XRD, SEM-EDX, and AFM has provided information about the structural (phase distribution, degree of crystallinity, and crystallite size), morphological (crystallite shape, degree of porosity), and tribological (surface roughness) properties of the PbO2 coatings, respectively. Electrochemical studies based on linear and cyclic voltammetry allowed comparison between electrodes prepared in MSA and classical electrodes prepared in HNO3. Pure α- or β-PbO2 and α + β mixtures were obtained depending on the conditions, being temperature the most influential deposition parameter. A temperature rise caused a transition to pure β-PbO2 and led to a higher degree of crystallinity with a progressive increase of crystallite size, always within the range of 10–30 nm, as well as to a remarkably higher roughness, from smooth (35–50 nm rms) to rough (up to 500 nm rms) surfaces. Low MSA and high lead(II) methanesulfonate concentrations were required to avoid the formation of excessively porous powdery coatings, as well as cracks, pits, and holes. Most of the coatings obtained in MSA were uniform, nanocrystalline, and moderately rough. Their electrocatalytic behaviour was comparable to that of the electrodes prepared in HNO3, showing an O2-overpotential of +0.66 V in 0.05 M Na2SO4 at pH 3.0. Such coatings can then be envisaged as suitable anodes for energy and water treatment applications. Prolonged electrolysis has shown their stability against leaching.

  • the deposition of nanostructured β pbo2 coatings from aqueous Methanesulfonic Acid for the electrochemical oxidation of organic pollutants
    Electrochemistry Communications, 2010
    Co-Authors: Ignasi Sires, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Highly crystalline, nanostructured, three-dimensional β-PbO2 coatings were successfully obtained by galvanostatic deposition from baths containing aqueous lead(II) and Methanesulfonic Acid (CH3SO3H). This constitutes a much more environmentally friendly methodology compared to plating of β-PbO2 in HNO3. The deposits exhibited high quality and good adherence. The crystallite size was in the range 20–30 nm and AFM imaging revealed very uniform, rough deposits (i.e., 255–275 nm rms). The oxidative destruction of Methyl Orange azo dye was studied by electrochemical advanced oxidation processes (EAOPs). An electro-Fenton process with a high surface area carbon-felt cathode performed better than the single anodic oxidation. Rapid and complete decolorisation was achieved following pseudo first-order kinetics. The stability of the β-PbO2 electrodes during the electrolyses was also demonstrated.

W Huang - One of the best experts on this subject based on the ideXlab platform.

  • formation of atmospheric molecular clusters of Methanesulfonic Acid diethylamine complex and its atmospheric significance
    Atmospheric Environment, 2020
    Co-Authors: Caixin Xu, Zihang Wang, Yajuan Feng, Teng Le Huang, Shuai Jiang, Jie Li, Yu Zhao, W Huang
    Abstract:

    Abstract Field observations in a marine atmospheric environment imply the occurrence of significant concentrations of dimethylamine (DMA) and diethylamine (DEA) as well as Methanesulfonic Acid (MSA) in particulate formation. Among these particulates, studies on the interaction of MSA with DMA are well known; however, fundamental studies relating to the environmental impact of DEA on aerosol formation and its nucleation ability relative to the known ones are lacking. In this research, quantum chemical calculations and cluster kinetic modeling were used to analyze the aerosol formation potential of the reaction of DEA with MSA. Structural and thermodynamic evidence demonstrate a strong clustering stability in the processes of new particle formation (NPF). Driven by proton transfer, the clusters exhibit a low free-energy barrier distributed along the diagonal. The results of cluster kinetic analysis indicate that the aerosol formation potential of the MSA-DEA system at the parts per trillion (ppt) level is inferior to that of sulfuric Acid (SA)–DMA, and slightly superior to that of SA–methylamine (MA) but far superior to that of MSA–DMA, implying a relatively strong nucleation capability for MSA-DEA system. This result implies that the MSA-DEA system plays a potentially significant role in NPF in the marine environment.

  • formation of atmospheric molecular clusters consisting of Methanesulfonic Acid and sulfuric Acid insights from flow tube experiments and cluster dynamics simulations
    Atmospheric Environment, 2019
    Co-Authors: Chunyu Wang, Teng Le Huang, Shuai Jiang, W Huang, Zhongquan Wang
    Abstract:

    Abstract In coastal regions and ocean areas, Methanesulfonic Acid (MSA; CH3SO3H) is present in considerable concentrations in the gas-phase and aerosols. It has been shown that MSA could contribute to growth and possibly form initial molecular cluster, which may lead to aerosol formation. However, quantitative concentrations and thermodynamic properties of MSA and sulfuric Acid (SA; H2SO4) in the presence of water (W; H2O) remain largely uncertain. In this study, flow tube reactor was used to investigate the effects of each reactant on new particle formation (NPF) in a multi-component system consisting of MSA, SA, and W. Particles were measured for different combinations of reactants. It showed that a different order for reactant addition led to different experimental results, where the added MSA vapor to the SA-W binary system presented an obvious bimodal structure, for ternary system with SA added to the MSA-W, the similar bimodal phenomenon was not observed. The composition of clusters in the air flow was further analyzed by the commercial Atmospheric Pressure Interface Time-of-Flight Mass Spectrometer (APi-TOF-MS, Tofwerk AG), which is equipped with a homemade chemical ionization (CI) source, mass peaks corresponding to clusters that contain smaller MSA or SA molecules were clearly observed, indicating that these clusters are exist and stable. In addition, quantum chemistry calculation-based evaporation rate values were applied in a cluster dynamics model to yield formation rates of 2.6 × 102 cm−3 s−1 and cluster concentrations under different simulation conditions. This study could provide some insight into how Acids interact in the atmosphere.

  • a study on the microscopic mechanism of Methanesulfonic Acid promoted binary nucleation of sulfuric Acid and water
    Atmospheric Environment, 2018
    Co-Authors: Hui Wen, Teng Le Huang, Shuai Jiang, W Huang, Chunyu Wang, Xiuqiu Peng, Yirong Liu
    Abstract:

    Abstract Methanesulfonic Acid (MSA) is believed to play an important role in the formation and growth of atmospheric organic aerosols and could facilitate the binary nucleation of sulfuric Acid (SA)–water (W). However, understanding of larger clusters formed by gas-phase MSA with atmospheric nucleation precursors from microscopic aspect is lacking. In this work, to study the microscopic mechanism of the ternary nucleation, the structural characteristics and thermodynamics of MSA clusters with SA in the presence of up to six W molecules have been investigated. It was found that MSA forms relatively stable clusters with SA and W molecules and that Acid dissociation plays an important role. The analysis of the atmospheric relevance indicates that the heterodimer MSA–SA and monohydrated cluster MSA–SA–W1 show an obvious relative concentration in the atmosphere, and thus, these species likely participate in new particle formation (NPF). However, with an increasing number of W molecules, the concentration of clusters gradually decreases. Additionally, the minimum energy isomer of MSA–SA–W4 is predicted to possess a relatively stable configuration under the employed temperature dependence analysis, and evaporation rate analysis. The detailed non-covalent interactions of MSA-SA-Wn, n = 3–6 cluster have been thoroughly studied for the first time.

C T J Low - One of the best experts on this subject based on the ideXlab platform.

  • zinc deposition and dissolution in Methanesulfonic Acid onto a carbon composite electrode as the negative electrode reactions in a hybrid redox flow battery
    Electrochimica Acta, 2011
    Co-Authors: Puiki Leung, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Electrodeposition and dissolution of zinc in Methanesulfonic Acid were studied as the negative electrode reactions in a hybrid redox flow battery. Cyclic voltammetry at a rotating disk electrode was used to characterize the electrochemistry and the effect of process conditions on the deposition and dissolution rate of zinc in aqueous Methanesulfonic Acid. At a sufficiently high current density, the deposition process became a mass transport controlled reaction. The diffusion coefficient of Zn2+ ions was 7.5 × 10−6 cm2 s−1. The performance of the zinc negative electrode in a parallel plate flow cell was also studied as a function of Zn2+ ion concentration, Methanesulfonic Acid concentration, current density, electrolyte flow rate, operating temperature and the addition of electrolytic additives, including potassium sodium tartarate, tetrabutylammonium hydroxide, and indium oxide. The current-, voltage- and energy efficiencies of the zinc-half cell reaction and the morphologies of the zinc deposits are also discussed. The energy efficiency improved from 62% in the absence of additives to 73% upon the addition of 2 × 10−3 mol dm−3 of indium oxide as a hydrogen suppressant. In aqueous Methanesulfonic Acid with or without additives, there was no significant dendrite formation after zinc electrodeposition for 4 h at 50 mA cm−2.

  • the characterisation of pbo2 coated electrodes prepared from aqueous Methanesulfonic Acid under controlled deposition conditions
    Electrochimica Acta, 2010
    Co-Authors: Ignasi Sires, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Abstract A series of PbO2 coatings on planar carbon substrates has been prepared by anodic deposition in aqueous Methanesulfonic Acid (MSA) under galvanostatic conditions. The effect of four experimental parameters, i.e., lead(II) methanesulfonate and MSA concentrations, current density, and temperature was analysed. Surface characterisation by XRD, SEM-EDX, and AFM has provided information about the structural (phase distribution, degree of crystallinity, and crystallite size), morphological (crystallite shape, degree of porosity), and tribological (surface roughness) properties of the PbO2 coatings, respectively. Electrochemical studies based on linear and cyclic voltammetry allowed comparison between electrodes prepared in MSA and classical electrodes prepared in HNO3. Pure α- or β-PbO2 and α + β mixtures were obtained depending on the conditions, being temperature the most influential deposition parameter. A temperature rise caused a transition to pure β-PbO2 and led to a higher degree of crystallinity with a progressive increase of crystallite size, always within the range of 10–30 nm, as well as to a remarkably higher roughness, from smooth (35–50 nm rms) to rough (up to 500 nm rms) surfaces. Low MSA and high lead(II) methanesulfonate concentrations were required to avoid the formation of excessively porous powdery coatings, as well as cracks, pits, and holes. Most of the coatings obtained in MSA were uniform, nanocrystalline, and moderately rough. Their electrocatalytic behaviour was comparable to that of the electrodes prepared in HNO3, showing an O2-overpotential of +0.66 V in 0.05 M Na2SO4 at pH 3.0. Such coatings can then be envisaged as suitable anodes for energy and water treatment applications. Prolonged electrolysis has shown their stability against leaching.

  • the deposition of nanostructured β pbo2 coatings from aqueous Methanesulfonic Acid for the electrochemical oxidation of organic pollutants
    Electrochemistry Communications, 2010
    Co-Authors: Ignasi Sires, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Highly crystalline, nanostructured, three-dimensional β-PbO2 coatings were successfully obtained by galvanostatic deposition from baths containing aqueous lead(II) and Methanesulfonic Acid (CH3SO3H). This constitutes a much more environmentally friendly methodology compared to plating of β-PbO2 in HNO3. The deposits exhibited high quality and good adherence. The crystallite size was in the range 20–30 nm and AFM imaging revealed very uniform, rough deposits (i.e., 255–275 nm rms). The oxidative destruction of Methyl Orange azo dye was studied by electrochemical advanced oxidation processes (EAOPs). An electro-Fenton process with a high surface area carbon-felt cathode performed better than the single anodic oxidation. Rapid and complete decolorisation was achieved following pseudo first-order kinetics. The stability of the β-PbO2 electrodes during the electrolyses was also demonstrated.

  • the influence of a perfluorinated cationic surfactant on the electrodeposition of tin from a Methanesulfonic Acid bath
    Journal of Electroanalytical Chemistry, 2008
    Co-Authors: C T J Low, F C Walsh
    Abstract:

    The influence of a perfluorinated, cationic surfactant on the electrodeposition of tin onto a copper surface was investigated. The electrolyte was 0.014 mol dm−3 SnSO4, 0.005 mol dm−3 hydroquinone and 12.5 vol.% Methanesulfonic Acid (1.93 mol dm−3 MSA) at 296 K, containing a controlled concentration (0–2.4 vol.%) of DuPont™ ForaFac® 1098 surfactant, corresponding to a concentration ratio of surfactant to stannous ions of 0–5.6. Cyclic (at static disc electrode) and linear sweep voltammetry (using the rotating disc electrode) were used to characterise the electrodeposition. The effects of potential sweep rate and electrode rotation speed are discussed. The influences of the surfactant on the region of complete mass transport control and hydrogen evolution are investigated. The effect of surfactant addition to the electrolyte was shown to be potential and flow-dependent. The absorption of surfactant on the electrode surface hindered the hydrogen evolution and resulted in a reduction in the peak and limiting current densities. The reduction of dissolved oxygen from the background electrolyte, in the presence or absence of surfactant, was also investigated. The morphology of electrodeposited tin is characterised; in the presence of surfactant, a compact surface morphology whereas rod-like deposits could be obtained at higher current densities.

  • electrodeposition of tin copper and tin copper alloys from a Methanesulfonic Acid electrolyte containing a perfluorinated cationic surfactant
    Surface & Coatings Technology, 2008
    Co-Authors: C T J Low, F C Walsh
    Abstract:

    Tin, copper and tin–copper alloys were electrodeposited from a Methanesulfonic Acid electrolyte containing a perfluorinated cationic surfactant at 296 K. The electrolyte composition was 0.02 to 0.05 mol dm− 3 SnSO4, 0.02 to 0.2 mol dm− 3 CuSO4, 12.5 to 15% vol MSA (1.9 to 2.3 mol dm− 3 CH3SO3H, pH < 1), 0.01 mol dm− 3 hydroquinone and 0.008 to 0.012% vol perfluorinated cationic surfactant. Electrodeposition was studied at a rotating disc electrode (RDE), a rotating cylinder electrode (RCE) and a rotating cylinder Hull (RCH) cell. Cyclic voltammetry and linear sweep voltammetry were used to investigate the current-potential relationships at static and rotating disc electrodes. Tin–copper alloys were deposited over a wide range of operating conditions to produce surface finishes from dark-grey (3 to 9 wt.% Cu), light-brown (50 to 60 wt.% Cu) and golden-yellow (70 to 80 wt.% Cu). The influences of copper(II) and surfactant concentration, applied current and surfactant adsorption were investigated; while the surface microstructure and composition of the deposits were studied.

Feng Zheng - One of the best experts on this subject based on the ideXlab platform.

  • determination of methyl methanesulfonate and ethyl methanesulfonate in Methanesulfonic Acid by derivatization followed by high performance liquid chromatography with ultraviolet detection
    IEEE Journal of Solid-state Circuits, 2017
    Co-Authors: Jie Zhou, Xiangyuan Zheng, Wenyuan Liu, Feng Zheng
    Abstract:

    Methanesulfonic Acid is routinely used in pharmaceuticals but can contain potentially genotoxic impurities such as methyl methanesulfonate and ethyl methanesulfonate. The aim of this study was to develop a simple high-performance liquid chromatography with ultraviolet detection method for determining methyl methanesulfonate and ethyl methanesulfonate in Methanesulfonic Acid. Samples (250 mg) in water/acetonitrile (200 μL) were first combined with 10.0 mol/L sodium hydroxide solution (270 μL). Then they were mixed with 2.0 mg/mL N,N-diethyldithiocarbamate (500 μL), diluted to 5 mL with N,N-dimethylacetamide and allowed to react at 80°C for 1 h. The derivatives were analyzed using gradient high-performance liquid chromatography with ultraviolet detection (277 nm) and structurally elucidated by liquid chromatography with mass spectrometry. With acetonitrile/5 mmol/L ammonium acetate solution as the eluent and 1 mL/min as the flow rate on a C18 column, the derivatives were eluted at 10.6 and 14.8 min. Good linearity (correlation coefficients > 0.999) and low limits of quantitation (0.6 ppm) were obtained. The recoveries were in the range of 80-115% with relative standard deviation < 5.0%. Finally, the established method was successfully used for the determination of methyl methanesulfonate and ethyl methanesulfonate in Methanesulfonic Acid.

Puiki Leung - One of the best experts on this subject based on the ideXlab platform.

  • corrosion of the zinc negative electrode of zinc cerium hybrid redox flow batteries in Methanesulfonic Acid
    Journal of Applied Electrochemistry, 2014
    Co-Authors: C Poncedeleon, Puiki Leung, F J Recio, P Herrasti, F C Walsh
    Abstract:

    Corrosion of zinc in aqueous Methanesulfonic Acid has been evaluated over a wide range of concentrations of Acid (0.5–5 mol dm−3), dissolved zinc (0.5–2 mol dm−3), and electrolyte temperature (22–50 °C). The corrosion rate of zinc, in terms of weight loss and the volume of hydrogen evolved, varied with time and it was found to be highly dependent on the surface state and electrolyte conditions. With an initial active layer of zinc present, the corrosion rate rapidly increased following a decline when the proton concentration in the solution decreased to ca. 0.56 mol dm−3. Organic and inorganic inhibitors were added to the electrolyte to suppress the zinc corrosion in 1 mol dm−3 Methanesulfonic Acid. The strong adsorption and blocking effects of cationic organic adsorption inhibitors, such as cetyltrimethyl ammonium bromide and butyltriphenyl phosphonium chloride, led to a significant decrease in zinc corrosion over a 10 h immersion period. With the addition of indium and lead ions inhibitors, the zinc surface showed less activity. Zinc corrosion continued to a smaller extent in the presence of these metallic inhibitors during the first few hours, but the metallic layer of the inhibitors did not cover the surface completely resulting in continued hydrogen evolution and making the inhibitors less effective at longer times.

  • zinc deposition and dissolution in Methanesulfonic Acid onto a carbon composite electrode as the negative electrode reactions in a hybrid redox flow battery
    Electrochimica Acta, 2011
    Co-Authors: Puiki Leung, C T J Low, C Poncedeleon, F C Walsh
    Abstract:

    Electrodeposition and dissolution of zinc in Methanesulfonic Acid were studied as the negative electrode reactions in a hybrid redox flow battery. Cyclic voltammetry at a rotating disk electrode was used to characterize the electrochemistry and the effect of process conditions on the deposition and dissolution rate of zinc in aqueous Methanesulfonic Acid. At a sufficiently high current density, the deposition process became a mass transport controlled reaction. The diffusion coefficient of Zn2+ ions was 7.5 × 10−6 cm2 s−1. The performance of the zinc negative electrode in a parallel plate flow cell was also studied as a function of Zn2+ ion concentration, Methanesulfonic Acid concentration, current density, electrolyte flow rate, operating temperature and the addition of electrolytic additives, including potassium sodium tartarate, tetrabutylammonium hydroxide, and indium oxide. The current-, voltage- and energy efficiencies of the zinc-half cell reaction and the morphologies of the zinc deposits are also discussed. The energy efficiency improved from 62% in the absence of additives to 73% upon the addition of 2 × 10−3 mol dm−3 of indium oxide as a hydrogen suppressant. In aqueous Methanesulfonic Acid with or without additives, there was no significant dendrite formation after zinc electrodeposition for 4 h at 50 mA cm−2.

  • ce iii ce iv in Methanesulfonic Acid as the positive half cell of a redox flow battery
    Electrochimica Acta, 2011
    Co-Authors: Puiki Leung, Ponce C De Leon, F C Walsh
    Abstract:

    The characteristics of the Ce(III)/Ce(IV) redox couple in Methanesulfonic Acid were studied at a platinum disk electrode (0.125 cm2) over a wide range of electrolyte compositions and temperatures: cerium (III) methanesulfonate (0.1–1.2 mol dm−3), Methanesulfonic Acid (0.1–5.0 mol dm−3) and electrolyte temperatures (295–333 K). The cyclic voltammetry experiments indicated that the diffusion coefficient of Ce(III) ions was 0.5 × 10−6 cm2 s−1 and that the electrochemical kinetics for the oxidation of Ce(III) and the reduction of Ce(IV) was slow. The reversibility of the redox reaction depended on the electrolyte composition and improved at higher electrolyte temperatures. At higher Methanesulfonic Acid concentrations, the degree of oxygen evolution decreased by up to 50% when the Acid concentration increased from 2 to 5 mol dm−3. The oxidation of Ce(III) and reduction of Ce(IV) were also investigated during a constant current batch electrolysis in a parallel plate zinc–cerium flow cell with a 3-dimensional platinised titanium mesh electrode. The current efficiencies over 4.5 h of the process Ce(III) to Ce(IV) and 3.3 h electrolysis of the reverse reaction Ce(IV) to Ce(III) were 94.0 and 97.6%, respectively. With a 2-dimensional, planar platinised titanium electrode (9 cm2 area), the redox reaction of the Ce(III)/Ce(IV) system was under mass-transport control, while the reaction on the 3-dimensional mesh electrode was initially under charge-transfer control but became mass-transport controlled after 2.5–3 h of electrolysis. The effect of the side reactions (hydrogen and oxygen evolution) on the current efficiencies and the conversion of Ce(III) and Ce(IV) are discussed.