Synergism between protocatechualdehyde and rare earth cerium(IV) ion on the corrosion of cold rolled steel in hydrochloric acid solution
✍ Scribed by X. H. Li; S. D. Deng; G. N. Mu; H. Fu
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- German
- Weight
- 258 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0947-5117
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✦ Synopsis
Abstract
The synergism between protocatechualdehyde (PAL, 3,4‐dihydroxy‐benzaldehye) and rare earth cerium(IV) ion (Ce^4+^) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) solution has been investigated by weight loss and potentiodynamic polarization methods. The results reveal that PAL has a moderate inhibitive effect, while Ce^4+^ has a poor effect. Incorporation of PAL with Ce^4+^ improves the inhibition performance significantly, and exhibits synergistic inhibition effect. The adsorption of individual PAL obeys the Temkin adsorption isotherm, and the adsorption of the complex of PAL and Ce^4+^ accords with the Temkin adsorption isotherm too. The thermodynamic parameters of adsorption heat (Δ__H__^0^), adsorption free energy (Δ__G__^0^), and adsorption entropy (Δ__S__^0^) are calculated and discussed. Polarization curves show that individual PAL acts as a mixed‐type inhibitor, while Ce^4+^ slightly inhibits the corrosion reaction. The complex of PAL and Ce^4+^ acts as a mixed‐type inhibitor, which drastically inhibits both anodic and cathodic reactions. Depending on the results, the synergism mechanism is proposed from the viewpoint of adsorption theory.