Characterization and Electrochemical Behavior of a Copper Ferrite Obtained by In Situ Precipitation from Aqueous Solutions
✍ Scribed by E. Barrado; F. Prieto; M. Vega; R. Pardo; J. Medina
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 139 KB
- Volume
- 12
- Category
- Article
- ISSN
- 1040-0397
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✦ Synopsis
The chemical composition, crystalline structure and properties of copper-bearing ferrites obtained by in situ coprecipitation from aqueous solutions depend on the experimental conditions. Under optimum conditions of pH, temperature, Fe(II)/Cu(II) ratio, stirrer rate and air ¯ow, a copper-bearing ferrite was obtained, whose chemical composition, determined by potentiometric titration, ICP-AES and XRF, is Cu 0,13 Fe II 0,87 Fe III 2 O 4 ÁnH 2 O. An investigation into the crystalline structure of the ferrite by thermal analysis (TGA, DTG and DSC) and XRD pointed to Cu x Fe 3-x O 4 ÁFe 3 O 4 ÁCuOÁnH 2 O as the most probable structure. Electrochemical analysis of the solid ferrite was performed in HCl and HClO 4 solutions using a carbon paste electrode (CPE). Successive cyclic voltammograms were registered and results suggest that solid species only participate in electrodic reactions during the ®rst scan. In the second and subsequent scans only dissolved species are involved, thus pointing to dissolution phenomena of the solid ferrite in the CPE: In perchloric acid, only peaks corresponding to the redox systems Fe 3 ads 1e À D Fe 2 ads and Cu 2 ads 2e À D Cu 0 were scanned, whereas in hydrochloric acid, the peaks corresponded to the systems FeCl 2Yads 1e À D FeCl ads Cl À , Cu 2 ads Cl À 1e À D CuCl s and CuCl s 1 e À D Cu s Cl À . The values of the half-peak potentials and their shift with the activity of hydrochloric acid con®rmed these reactions. Chronopotentiometric analysis at a CPE containing copper ferrite further con®rmed the proposed mechanisms.