A potential corrosion inhibitor for acid corrosion of mild steel

Abstract

The inhibitory action of methionine, a naturally occurring organic compound, on the corrosion of mild steel in hydrochloric and sulphuric acid solutions was studied using gravimetric technique. The corrosion rates of mild steel in the two acid solutions containing methionine were measured as a function of the inhibitor concentration. The inhibition efficiency of methionine depends on the nature of the acid and the concentration of the inhibitor. The inhibition occurs through adsorption of the inhibitor molecules on the surface without modifying the kinetics of corrosion process, which is first order with respect to mild steel in both the acid solutions. The value of ΔGads for the adsorption process obtained using the Temkin adsorption isotherm reveals a strong interaction of methionine on mild steel surface in the acids. The difference in the inhibition behaviour of methionine in the acids has been explained in terms of metal-corrodant-inhibitor interactions.