LAUSR

Abstract Phosphonate metal organic frameworks synthesized starting from a 1:1 ratio of corresponding nitrate and vinylphosphonic acid (VP) in hydrothermal conditions were analyzed by FTIR, X-Ray powder diffraction, elemental analysis and thermogravimetric analysis. The ability Co and Zn vinylphosphonate molecules to anchor on the surface of the iron were investigated. Their binding stability on iron surface in acid saline solution was tested by electrochemical methods (polarization curve- CP and electrochemical impedance spectroscopy -EIS) and ATR-FT-IR. A 2 mM concentration of CoVP allows the formation of a protective layer on the iron surface which provides 96.8% inhibitory efficiency (IE), close to that provided by the corresponding phosphonic acid VP. The low corrosion rate in the presence of CoVP as compared to ZnVP may be due to the lower hydrolytic stability of CoVP. Following the hydrolysis reaction, the phosphonic acid is released. Phosphonic acid released further binds to the metallic surface and thus improves the quality of the protective film.