Pub Date : 2021-10-28DOI: 10.5189/revpolarography.67.85
N. Nishi
{"title":"72nd Annual Meeting of the International Society of Electrochemistry","authors":"N. Nishi","doi":"10.5189/revpolarography.67.85","DOIUrl":"https://doi.org/10.5189/revpolarography.67.85","url":null,"abstract":"","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131996790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-28DOI: 10.5189/revpolarography.67.67
M. Hojo
The greatly enhanced oxidation ability of dilute aqueous nitric acid (0.10–2.0 mol dm-3) containing bromide and iodide salts as well as chloride salts has been examined based on the dissolution kinetics of pure gold at 30–60 °C. It has been found that bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol dm-3 HNO3 solution containing 1.0–5.0 mol dm-3 NaBr and the dissolution rate constant, log(k/s-1), increases linearly (from -5.78 to -4.52) with the increasing NaBr concentration. The gold dissolution ability has been examined also with nitrous acid containing chloride and bromide ions at 35 °C. The NaNO2 solution containing twice or more amounts of HX (X = Cl, Br) gives the maximum efficiency for gold dissolution, according to the log(k/s-1) values of the mixed solutions of NaNO2 (0.10–2.0 mol dm-3) and HX of various concentrations. The influence of oxidation by dilute nitric and nitrous acids on the gold dissolution is discussed from the standpoint of the redox potentials in ‘‘modified’’ aqueous solutions and not of the changes in the activity coefficients of ions. The corrosion of stainless-steel (SUS316L) in dilute nitric acid containing NaCl or NaBr has been also examined to find that the passive film on the surface is broken down by the evolved Cl2 or Br2 gas.
{"title":"Pure Gold Dissolution and Stainless-Steel Corrosion in Dilute Nitric or Nitrous Acid Containing Halide Salts","authors":"M. Hojo","doi":"10.5189/revpolarography.67.67","DOIUrl":"https://doi.org/10.5189/revpolarography.67.67","url":null,"abstract":"The greatly enhanced oxidation ability of dilute aqueous nitric acid (0.10–2.0 mol dm-3) containing bromide and iodide salts as well as chloride salts has been examined based on the dissolution kinetics of pure gold at 30–60 °C. It has been found that bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol dm-3 HNO3 solution containing 1.0–5.0 mol dm-3 NaBr and the dissolution rate constant, log(k/s-1), increases linearly (from -5.78 to -4.52) with the increasing NaBr concentration. The gold dissolution ability has been examined also with nitrous acid containing chloride and bromide ions at 35 °C. The NaNO2 solution containing twice or more amounts of HX (X = Cl, Br) gives the maximum efficiency for gold dissolution, according to the log(k/s-1) values of the mixed solutions of NaNO2 (0.10–2.0 mol dm-3) and HX of various concentrations. The influence of oxidation by dilute nitric and nitrous acids on the gold dissolution is discussed from the standpoint of the redox potentials in ‘‘modified’’ aqueous solutions and not of the changes in the activity coefficients of ions. The corrosion of stainless-steel (SUS316L) in dilute nitric acid containing NaCl or NaBr has been also examined to find that the passive film on the surface is broken down by the evolved Cl2 or Br2 gas.","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126004135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-28DOI: 10.5189/revpolarography.67.57
T. Okada
When an aqueous solution freezes, solutes are expelled from ice crystals and accumulate in the grain boundary space. The solutes dissolve to form a freeze concentrated solution (FCS) at temperature higher than the eutectic point of the system. It is known that the FCS is involved in various reactions of environmental and atmospheric importance. We have found interesting phenomena occurring in the FCS using a variety of analytical methods, such as chromatography, electrophoresis, fluorescence spectroscopy and lifetime measurements, X-ray spectroscopy, voltammetry etc. Here, we present some of them and discuss the ice-confinement effects on the chemical processes in the FCS.
{"title":"Chemistry in Ice-Confined Space","authors":"T. Okada","doi":"10.5189/revpolarography.67.57","DOIUrl":"https://doi.org/10.5189/revpolarography.67.57","url":null,"abstract":"When an aqueous solution freezes, solutes are expelled from ice crystals and accumulate in the grain boundary space. The solutes dissolve to form a freeze concentrated solution (FCS) at temperature higher than the eutectic point of the system. It is known that the FCS is involved in various reactions of environmental and atmospheric importance. We have found interesting phenomena occurring in the FCS using a variety of analytical methods, such as chromatography, electrophoresis, fluorescence spectroscopy and lifetime measurements, X-ray spectroscopy, voltammetry etc. Here, we present some of them and discuss the ice-confinement effects on the chemical processes in the FCS.","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132775673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-21DOI: 10.5189/REVPOLAROGRAPHY.67.19
K. Miyazaki
Rechargeable batteries are needed as a buffer to store excess electric power and supplement it when needed, to significantly promote the introduction of renewable energy such as wind power, solar power, etc. In this study, platinum-array electrodes and rotating-ring-disk electrodes were used as a tool to investigate the electrode reactions of rechargeable batteries using aqueous solutions as electrolytes.
{"title":"Reaction analysis of aqueous-based energy storage devices with electrode modeling","authors":"K. Miyazaki","doi":"10.5189/REVPOLAROGRAPHY.67.19","DOIUrl":"https://doi.org/10.5189/REVPOLAROGRAPHY.67.19","url":null,"abstract":"Rechargeable batteries are needed as a buffer to store excess electric power and supplement it when needed, to significantly promote the introduction of renewable energy such as wind power, solar power, etc. In this study, platinum-array electrodes and rotating-ring-disk electrodes were used as a tool to investigate the electrode reactions of rechargeable batteries using aqueous solutions as electrolytes.","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128159244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-21DOI: 10.5189/REVPOLAROGRAPHY.67.25
H. Nagatani
{"title":"66th Meeting of the Polarographic Society of Japan in Taipei","authors":"H. Nagatani","doi":"10.5189/REVPOLAROGRAPHY.67.25","DOIUrl":"https://doi.org/10.5189/REVPOLAROGRAPHY.67.25","url":null,"abstract":"","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122364412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-21DOI: 10.5189/REVPOLAROGRAPHY.67.1
Yukari Sato
{"title":"Important things that can only be understood after losing an opportunity","authors":"Yukari Sato","doi":"10.5189/REVPOLAROGRAPHY.67.1","DOIUrl":"https://doi.org/10.5189/REVPOLAROGRAPHY.67.1","url":null,"abstract":"","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117010278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-21DOI: 10.5189/REVPOLAROGRAPHY.67.11
H. Hotta
The oxidation reaction mechanisms of chlorogenic acid and caffeic acid, were studied by various electrochemical studies. Cyclic voltammetry (CV) and its digital simulation analysis, flow coulometry, and analysis of electrolytic oxidation products by HPLC-UV, ECD, MS detection were performed. These measurements clarified the mechanism of dimer formation associated with oxidation and the resulting increase in reducing power of the polyphenols. The reaction between DPPH radical and several antioxidants were monitored by CV. Antioxidants were classified into three groups with different reaction mechanisms depending on the substitution position of the OH group. The linear correlation between the DPPH radical scavenging activity and the number of electrons involved in the oxidation, n value, was proved. Thus, it was revealed that the subsequent chemical reaction following the oxidation is a key reaction that influences the antioxidant activity. Through the development of the electron conductor separating oil water (ECSOW) system and digital simulation analysis of CV, it was clarified that the electron transfer at the oil-water interface between Fe(CN)6 and ferrocene is proceeding by the ion transfer mechanism. A novel analytical method called liquid-liquid optical waveguide spectroscopy was developed, and fast electron transfer between ascorbic acid and DPPH radical at the miscible liquid/liquid interface was observed by the method.
{"title":"Approach to elucidate the reaction mechanism of natural antioxidants using electrochemical methods","authors":"H. Hotta","doi":"10.5189/REVPOLAROGRAPHY.67.11","DOIUrl":"https://doi.org/10.5189/REVPOLAROGRAPHY.67.11","url":null,"abstract":"The oxidation reaction mechanisms of chlorogenic acid and caffeic acid, were studied by various electrochemical studies. Cyclic voltammetry (CV) and its digital simulation analysis, flow coulometry, and analysis of electrolytic oxidation products by HPLC-UV, ECD, MS detection were performed. These measurements clarified the mechanism of dimer formation associated with oxidation and the resulting increase in reducing power of the polyphenols. The reaction between DPPH radical and several antioxidants were monitored by CV. Antioxidants were classified into three groups with different reaction mechanisms depending on the substitution position of the OH group. The linear correlation between the DPPH radical scavenging activity and the number of electrons involved in the oxidation, n value, was proved. Thus, it was revealed that the subsequent chemical reaction following the oxidation is a key reaction that influences the antioxidant activity. Through the development of the electron conductor separating oil water (ECSOW) system and digital simulation analysis of CV, it was clarified that the electron transfer at the oil-water interface between Fe(CN)6 and ferrocene is proceeding by the ion transfer mechanism. A novel analytical method called liquid-liquid optical waveguide spectroscopy was developed, and fast electron transfer between ascorbic acid and DPPH radical at the miscible liquid/liquid interface was observed by the method.","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133565361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-21DOI: 10.5189/REVPOLAROGRAPHY.67.3
Grégoire C Gschwend, Astrid J. Olaya, Danick Reynard, H. Girault
After discussing the fundamental issue of charge distributions at polarized interfaces, we present the concept of the “Discrete Helmholtz Model” for liquid-liquid interfaces and also for other non-metallic interfaces. We introduce the newly discovered ionosomes, which are nano liquid-liquid interfaces. We finish by presenting our work of water splitting using redox electrocatalysis in a batch mode, using an aqueous redox battery and finally using molecular electrocatalysts.
{"title":"Development and applications of electrochemistry at soft interfaces and nanoparticles","authors":"Grégoire C Gschwend, Astrid J. Olaya, Danick Reynard, H. Girault","doi":"10.5189/REVPOLAROGRAPHY.67.3","DOIUrl":"https://doi.org/10.5189/REVPOLAROGRAPHY.67.3","url":null,"abstract":"After discussing the fundamental issue of charge distributions at polarized interfaces, we present the concept of the “Discrete Helmholtz Model” for liquid-liquid interfaces and also for other non-metallic interfaces. We introduce the newly discovered ionosomes, which are nano liquid-liquid interfaces. We finish by presenting our work of water splitting using redox electrocatalysis in a batch mode, using an aqueous redox battery and finally using molecular electrocatalysts.","PeriodicalId":305513,"journal":{"name":"Review of Polarography","volume":"162 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114679683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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