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 HCl and 0.5 M H sub 2 SO sub 4 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 HCl and H sub 2 SO sub 4 in the order ortho > meta > para. It is observed that the inhibition is greater in HCl than in H sub 2 SO sub 4 . The predominant behaviour is in the cathodic inhibitor mode. These compounds reduce the permeation current in 1 M HCl and enhance it in 0.5 M H sub 2 SO sub 4 . The adsorption of these compounds on mild steel in 1 M HCl and 0.5 M H sub 2 SO sub 4 obeys Langmuir's adsorption isotherm.