Crossandra infundibuliformis Leaves as an Effective Inhibitor for Mild Steel Corrosion in 1 M HCl

Corrosion inhibition of mild steel in 1 M HCl was investigated in the absence and presence of different concentrations of extract of Crossandra infundibuliformis leaves. Weight loss measurements and electrochemical studies were employed. The corrosion rate of mild steel and the inhibition efficiencies of the extract were calculated. The results obtained show that the extract solution of the plant could serve as an effective inhibitor for the corrosion of mild steel in HCl media. Inhibition was found to increase with increasing concentration of the plant extract. The inhibitive actions of plant extract are discussed on the basis of adsorption of stable complex at the mild steel surface. Theoretical fitting of different isotherms, Langmuir, Temkin, Freundlich, Frumkin, Flory-Huggins and the kinetic thermodynamic model were tested to clarify the nature of adsorption. Polarisation curves revealed that this inhibitor act as a mixed type inhibitor and the inhibition efficiency up to 97.41% can be obtained. The surface analysis study confirms the corrosion of mild steel and its inhibition by the inhibitor.