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The reducibility of sulphuric acid and sulphate in aqueous solution

Technical Report:

Abstract

In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100{sup o}C. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300{sup o}C. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130{sup o}C, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible  More>>
Authors:
Grauer, R [1] 
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Publication Date:
Jul 01, 1991
Product Type:
Technical Report
Report Number:
PSI-109
Reference Number:
SCA: 400201; PA: AIX-23:014096; SN: 92000646597
Resource Relation:
Other Information: PBD: Jul 1991
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COPPER; CORROSION; SULFATES; REDUCTION; SULFURIC ACID; COMPILED DATA; ELECTROCHEMISTRY; EXPERIMENTAL DATA; REDOX POTENTIAL; THERMODYNAMICS; 400201; CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
OSTI ID:
10113108
Research Organizations:
Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Country of Origin:
Switzerland
Language:
English
Other Identifying Numbers:
Other: ON: DE92614765; TRN: CH9100671014096
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
CHN
Size:
41 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Grauer, R. The reducibility of sulphuric acid and sulphate in aqueous solution. Switzerland: N. p., 1991. Web.
Grauer, R. The reducibility of sulphuric acid and sulphate in aqueous solution. Switzerland.
Grauer, R. 1991. "The reducibility of sulphuric acid and sulphate in aqueous solution." Switzerland.
@misc{etde_10113108,
title = {The reducibility of sulphuric acid and sulphate in aqueous solution}
author = {Grauer, R}
abstractNote = {In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100{sup o}C. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300{sup o}C. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130{sup o}C, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible metal/metal-sulphate electrodes of lead and cadmium are unstable relative to the corresponding metal sulphides. Nevertheless the reversible lead sulphate electrode does not fail from sulphide formation. All these facts confirm that sulphur(VI) in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be almost certainly be ruled out. (author) 5 figs., 85 refs.}
place = {Switzerland}
year = {1991}
month = {Jul}
}