Mechanism of corrosion inhibition by the 2‐chloroethyl phosphonic acid – Zn2+ system

Abstract

The synergistic effect of sodium salt of 2‐chloroethyl phosphonic acid (2‐Cl EPA) and Zn2+, in controlling corrosion of carbon steel in a neutral aqueous environment containing 60ppm Cl–, was evaluated by weight‐loss and electrochemical methods. A formulation consisting of 300ppm 2‐Cl EPA and 300ppm Zn2+ was observed to deliver 95 percent inhibition efficiency. A suitable mechanism of corrosion inhibition has been proposed which is based on the results obtained from polarization study and uv‐visible absorption and reflectance spectra. 2‐Cl EPA‐Zn2+ system appears to function as a mixed inhibitor. The protective film consisted of Fe2+ ‐2‐Cl EPA complex, Zn(OH)2 and oxides of iron. The film was found to be semiconducting in nature.