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Synergism between protocatechualdehyde and rare earth cerium(IV) ion on the corrosion of cold rolled steel in hydrochloric acid solution
Author(s) -
Li X. H.,
Deng S. D.,
Mu G. N.,
Fu H.
Publication year - 2010
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200905283
Subject(s) - adsorption , cerium , hydrochloric acid , corrosion , chemistry , inorganic chemistry , polarization (electrochemistry) , ion , organic chemistry
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.