Influence of anions on the performance of isomers of aminobenzoic acid on the corrosion inhibition and hydrogen permeation through mild steel in acidic solutions

The influence of aminobenzoic acids on the corrosion and hydrogen permeation through mild steel in 1 m HC1 and 0.5 M H2SO4 has been studied using weight loss and gasometric measurements and various electrochemical techniques. All the three isomers of aminobenzoic acid inhibit the corrosion of mild steel both in HC1 and H2SO4 in the order ortho > meta > para. It is observed that the inhibition is greater in HCI than in H2SO4. The predominant behaviour is in the cathodic inhibitor mode. These compounds reduce the permeation current in 111 HCl and enhance it in 0.51 v1 H2SO4. The adsorption of these compounds on mild steel in 1 m HC1 and 0.5 m H2SO4 obeys Langmuir's adsorption isotherm.