Voltammetric investigation of the two step reduction process of hydrogen peroxide in alkaline hydroxide solutions on HMDE

✍ Scribed by Ewa Bednarkiewicz; Zenon Kublik

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 750 KB
• Volume: 24
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(79)80014-6

✦ Synopsis

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-The voltammetric behaviour of hydrogen peroxide has been studied at the hmde in alkaline medium. It has been confirmed that the first of the two reduction peaks of hydrogen peroxide is catalytic in nature; t&es of ferric iron act under these conditions as a catalyst. In thoroughly purified potassium hydroxide solutions the height of this peak decreases and it can be aho completely eliminated, even in the presence of Fe(III), if some agents capable of forming complexes with Fe(III) are added to a solution. The rate constant of the catalytic reaction proceeding between the hydroxo complex of Fe(II) and hydrogen peroxide in 1 M potassium hydroxide solution was estimated to bc 5.6 x lo9 mol-' 1. s-'. INTRODUCX-ION The two step polarographic reduction of hydrogen peroxide into two distinct waves in solutions of alkali hydroxides is firmly established[f-71. There are. however serious discrepancies regarding the explanation of the nature of the split. On the one hand Biiaina[4] supposed that in the first step of the split wave the hydrogen peroxide is reduced catalytically. The hydroxocomplex of iron/III), which is always present at trace level even in the purest alkaline hydroxide solutions, acts under these conditions as a catalyst. According to this mechanism the second step reflects simply the undisturbed, irreversible reduction of hydrogen peroxide.