The role of phosphonates as transporters of Zn(2+) ions in the inhibition of carbon steel in neutral solutions containing chlorides

Phosphonates have shown synergistic effects in combination with Zn2+ ions in controlling the corrosion of carbon steel immersed in neutral aqueous environments containing 60-ppm Cl-. The role of phosphonates in the presence of Zn2+ ions has been investigated by polarisation tests and weight loss res...

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Bibliographic Details
Published in:Anti-corrosion methods and materials 2002, Vol.49 (3), p.205-205
Main Authors: Rajendran, S, Apparao, B V, Palaniswamy, N, Amalraj, A J, Sundaravadivelu, M
Format: Article
Language:English
Subjects:
Acids
Carbon steel
Corrosion
Corrosion inhibitors
Efficiency
Experiments
Investigations
Ions
Phosphates
Synergistic effect
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Summary:Phosphonates have shown synergistic effects in combination with Zn2+ ions in controlling the corrosion of carbon steel immersed in neutral aqueous environments containing 60-ppm Cl-. The role of phosphonates in the presence of Zn2+ ions has been investigated by polarisation tests and weight loss results. It was observed that the phosphonates functioned as transporters of Zn2+ ions from the bulk of the solution towards the metal surface. The phosphonate-Zn2+ bond is sufficiently strong to carry Zn2+ ions from the bulk solution towards the metal surface, but is weak enough for them to break to form a phosphonate-Fe2+ bond at anodic sites on the metal surface. Inhibition efficiency increases when the phosphonate-Zn2+ complex remains in solution in soluble form. Inhibition efficiency decreased when the phosphonate-Zn2+ complex was precipitated in the bulk of the solution.
ISSN:0003-5599
1758-4221
DOI:10.1108/00035590210426472