Phosphonic Acids used as Corrosion Inhibitors-A Review

Abstract

Inhibition of corrosion and scaling can be done by the application of inhibitors. It is noted that the effect of corrosion inhibitors is always caused by change in the state of surface being protected due to adsorption or formation of hardly soluble compounds with metal cations. Several phosphonic acids have been used as corrosion inhibitor along with metal cation such as Zn²⁺. The synergistic effect between the inhibitors gives the more inhibition efficiency. Phosphonic acids are inhibitors, which have been used due to their stability, ability to form complexes with metal cations. They are adsorbed on metal surface through these polar atoms. The adsorption obeys various adsorption isotherms. The film have been analyzed by many technologies such as, FTIR, SEM, UV-Visible spectra, EIS and electrochemical studies like polarization and AC impedance.