Inhibitor effect of succinic acid on the corrosion resistance of mild steel: electrochemical, gravimetric and optical microscopic studies

The inhibitor effect of succinic acid on the corrosion resistance of mild steel in sulfuric acid solutions was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, weight loss and optical microscopic analysis. The results suggest that succinic acid acts: (i) slightly shifting the corrosion potential towards less negative values; (ii) decreasing both the anodic dissolution of mild steel and the hydrogen evolution reaction. Inhibition efficiencies of up to 80% were recorded for pH=2 and 3 solutions, whereas no effect was perceived for pH>4 solutions. The results have been understood taking into account the solution composition as function of pH.