Mechanism of corrosion inhibition by the 2-chloroethyl phosphonic acid -: Zn2+ system

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.