Synergistic Influence of Benzoate Ions on Inhibition of Corrosion of Mild Steel in 0.5m Sulfuric Acid by Benzotriazole

The influence of benzoate anions on the corrosion inhibition effect of benzotriazole (BTA) for mild steel in sulfuric acid has been investigated. The investigation was carried out by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The addition of benzoate ions greatly enhances the inhibition efficiency of BTA in a synergistic manner. This effect has been attributed to co-adsorption of benzoate and protonated benzotriazole ions. While inhibition property of BTA has been attributed to adsorption of the molecules on the metal surface, through interaction of lone pair electrons on nitrogen atoms or π electrons of the aromatic ring, followed by polymeric complex formation. In acid solution, in presence of benzoate anions, protonated BTA molecules are adsorbed mostly by columbic attractions on the surface partially covered with benzoate anions.