Electrochemical reduction of bisulfite in mildly acidic buffers

Kinetics of sulfur dioxide - Bisulfite interconversion

Yuriy V. Tolmachev, Daniel Alberto Scherson

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The reduction of bisulfite on a bismuth rotating disk electrode (RDE) was studied in aqueous buffered electrolytes over the pH range 3-6. Clearly defined limiting currents were observed in all solutions examined; however, their magnitudes were not only smaller than those expected for a process limited by the diffusion of bisulfite from the bulk solution, but were also found to decrease as the media became less acidic. This behavior was attributed to a preceding homogeneous process that generates sulfur dioxide, the actual electroactive species. UV - visible absorption - reflection spectroscopy measurements at a RDE showed that in the potential region in which such limiting currents are observed, dithionite is produced with 100% faradaic efficiency, Results of rotation rate staircase scan amperometric RDE experiments were found to be consistent with the conversion of bisulfite into SO2 proceeding via a general acid catalysis mechanism, and allowed values for the rate constants for the following reactions to be determined: SO2 + H2O → HSO3 - + H3O+, kb = (1.6 ± 0.2) 107 s-1; HSO3 - + H3O → SO2 + H2O, kf H = (1.2 ± 0.15) 109 M-1 s-1; HSO3 - + CH3COOH → SO2 + H2O + CH3COO-, kf HA = (1.7 ± 0.5) 104 M-1 s-1. On this basis, and assuming diffusion-controlled rates for proton transfer from strong acids to oxygen bases, a more detailed mechanism involving formation of sulfurous acid as an intermediate is discussed and some thermodynamic and kinetic properties of the latter are estimated.

Original languageEnglish
Pages (from-to)1572-1578
Number of pages7
JournalJournal of Physical Chemistry A
Volume103
Issue number11
DOIs
Publication statusPublished - 1999 Mar 18
Externally publishedYes

Fingerprint

Sulfur Dioxide
sulfur dioxides
rotating disks
Rotating disks
Buffers
buffers
Electrodes
acids
Kinetics
electrodes
kinetics
Sulfur Acids
Dithionite
Bismuth
Acids
Proton transfer
stairways
bismuth
Electrolytes
Catalysis

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Electrochemical reduction of bisulfite in mildly acidic buffers : Kinetics of sulfur dioxide - Bisulfite interconversion. / Tolmachev, Yuriy V.; Scherson, Daniel Alberto.

In: Journal of Physical Chemistry A, Vol. 103, No. 11, 18.03.1999, p. 1572-1578.

Research output: Contribution to journalArticle

@article{c3f92260035343afaa072c71c12ab9b8,
title = "Electrochemical reduction of bisulfite in mildly acidic buffers: Kinetics of sulfur dioxide - Bisulfite interconversion",
abstract = "The reduction of bisulfite on a bismuth rotating disk electrode (RDE) was studied in aqueous buffered electrolytes over the pH range 3-6. Clearly defined limiting currents were observed in all solutions examined; however, their magnitudes were not only smaller than those expected for a process limited by the diffusion of bisulfite from the bulk solution, but were also found to decrease as the media became less acidic. This behavior was attributed to a preceding homogeneous process that generates sulfur dioxide, the actual electroactive species. UV - visible absorption - reflection spectroscopy measurements at a RDE showed that in the potential region in which such limiting currents are observed, dithionite is produced with 100{\%} faradaic efficiency, Results of rotation rate staircase scan amperometric RDE experiments were found to be consistent with the conversion of bisulfite into SO2 proceeding via a general acid catalysis mechanism, and allowed values for the rate constants for the following reactions to be determined: SO2 + H2O → HSO3 - + H3O+, kb = (1.6 ± 0.2) 107 s-1; HSO3 - + H3O → SO2 + H2O, kf H = (1.2 ± 0.15) 109 M-1 s-1; HSO3 - + CH3COOH → SO2 + H2O + CH3COO-, kf HA = (1.7 ± 0.5) 104 M-1 s-1. On this basis, and assuming diffusion-controlled rates for proton transfer from strong acids to oxygen bases, a more detailed mechanism involving formation of sulfurous acid as an intermediate is discussed and some thermodynamic and kinetic properties of the latter are estimated.",
author = "Tolmachev, {Yuriy V.} and Scherson, {Daniel Alberto}",
year = "1999",
month = "3",
day = "18",
doi = "10.1021/jp983752c",
language = "English",
volume = "103",
pages = "1572--1578",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
number = "11",

}

TY - JOUR

T1 - Electrochemical reduction of bisulfite in mildly acidic buffers

T2 - Kinetics of sulfur dioxide - Bisulfite interconversion

AU - Tolmachev, Yuriy V.

AU - Scherson, Daniel Alberto

PY - 1999/3/18

Y1 - 1999/3/18

N2 - The reduction of bisulfite on a bismuth rotating disk electrode (RDE) was studied in aqueous buffered electrolytes over the pH range 3-6. Clearly defined limiting currents were observed in all solutions examined; however, their magnitudes were not only smaller than those expected for a process limited by the diffusion of bisulfite from the bulk solution, but were also found to decrease as the media became less acidic. This behavior was attributed to a preceding homogeneous process that generates sulfur dioxide, the actual electroactive species. UV - visible absorption - reflection spectroscopy measurements at a RDE showed that in the potential region in which such limiting currents are observed, dithionite is produced with 100% faradaic efficiency, Results of rotation rate staircase scan amperometric RDE experiments were found to be consistent with the conversion of bisulfite into SO2 proceeding via a general acid catalysis mechanism, and allowed values for the rate constants for the following reactions to be determined: SO2 + H2O → HSO3 - + H3O+, kb = (1.6 ± 0.2) 107 s-1; HSO3 - + H3O → SO2 + H2O, kf H = (1.2 ± 0.15) 109 M-1 s-1; HSO3 - + CH3COOH → SO2 + H2O + CH3COO-, kf HA = (1.7 ± 0.5) 104 M-1 s-1. On this basis, and assuming diffusion-controlled rates for proton transfer from strong acids to oxygen bases, a more detailed mechanism involving formation of sulfurous acid as an intermediate is discussed and some thermodynamic and kinetic properties of the latter are estimated.

AB - The reduction of bisulfite on a bismuth rotating disk electrode (RDE) was studied in aqueous buffered electrolytes over the pH range 3-6. Clearly defined limiting currents were observed in all solutions examined; however, their magnitudes were not only smaller than those expected for a process limited by the diffusion of bisulfite from the bulk solution, but were also found to decrease as the media became less acidic. This behavior was attributed to a preceding homogeneous process that generates sulfur dioxide, the actual electroactive species. UV - visible absorption - reflection spectroscopy measurements at a RDE showed that in the potential region in which such limiting currents are observed, dithionite is produced with 100% faradaic efficiency, Results of rotation rate staircase scan amperometric RDE experiments were found to be consistent with the conversion of bisulfite into SO2 proceeding via a general acid catalysis mechanism, and allowed values for the rate constants for the following reactions to be determined: SO2 + H2O → HSO3 - + H3O+, kb = (1.6 ± 0.2) 107 s-1; HSO3 - + H3O → SO2 + H2O, kf H = (1.2 ± 0.15) 109 M-1 s-1; HSO3 - + CH3COOH → SO2 + H2O + CH3COO-, kf HA = (1.7 ± 0.5) 104 M-1 s-1. On this basis, and assuming diffusion-controlled rates for proton transfer from strong acids to oxygen bases, a more detailed mechanism involving formation of sulfurous acid as an intermediate is discussed and some thermodynamic and kinetic properties of the latter are estimated.

UR - http://www.scopus.com/inward/record.url?scp=0013176150&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0013176150&partnerID=8YFLogxK

U2 - 10.1021/jp983752c

DO - 10.1021/jp983752c

M3 - Article

VL - 103

SP - 1572

EP - 1578

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 11

ER -