Electrocatalysis of anodic oxygen-transfer reactions: Oxidation of Cr(III) to Cr(VI) at Bi(V)-doped PbO{sub 2}-film electrodes
- Iowa State Univ., Ames, IA (United States)
Voltammetric and coulometric results are described for the electrocatalytic oxidation of Cr(III) to Cr(VI) at the mixed bismuth(V)-lead(IV) dioxide film electrodes (designated Bi-PbO{sub 2}) that are electrodeposited from acidic solutions of Pb(II) containing Bi(III). A current efficiency of 99.2% ({sigma} = 1.1%, N = 12) is obtained for galvanostatic generation of Cr(VI) at a preconditioned Bi-PbO{sub 2} film electrode. Preconditioning of the Bi-PbO{sub 2} film merely involves the generation of Cr(VI) which, based on scanning electron micrographs, is concluded tentatively to achieve chemical stripping of noncatalytic portions of the Bi-PbO{sub 2} films to produce films having greater electrocatalytic activity for the desired reaction. Electrochemical stripping of the Bi-PbO{sub 2} electrode had a similar preconditioning effect. Based on wavelength dispersive spectroscopy, electrochemical stripping resulted in an increase in surface Bi concentration of 33% relative to Pb. Research described here is motivated by the goal of automating the determination of chemical oxygen demand (COD) of polluted waters on the basis of an indirect coulometric procedure that utilizes an electrochemically generated oxidation mediator. The standard method for determination of COD in organically polluted waters utilizes Cr(VI) with back titration of excess oxidant using a standard solution of Fe(II).
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 367760
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 7 Vol. 143; ISSN 0013-4651; ISSN JESOAN
- Country of Publication:
- United States
- Language:
- English
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