Abstract
The extract of harmal (HE) in aqueous 1 M HCl was systematically investigated to ascertain its inhibitor y effect on corrosion of C-steel and its mechanism of the inhibition by electrochemical and weight loss methods.The inhibition efficiency of harmal extract (HE) on corrosion of C-steel in 1 M HCl solution ion increases on increasing in its concentration and decreases with rise in temperature. Potentiodynamic polarization measurement show that HE acts as cathodic type inhibitor. The increase in activation in energies of corrosion process in presence of the extract indicates that HE retarded the rate of corrosion of C-steel in 1 M HCl solution. The nature of adsorption of the extract on C-steel surface was in conformity with Langmuir isotherm. The results obtained with different method are in good agreement. Scanning electron microscopy (SEM) study confirmed that the inhibition of corrosion of C-steel is through adsorption of the extract molecules on surface of metal.