Pennyroyal oil from Mentha pulegium as corrosion inhibitor for steel in 1 M HCl

Natural oil extracted from Pennyroyal Mint (Mentha pulegium, PM) was evaluated as corrosion inhibitor of steel in molar hydrochloric using weight loss measurements, electrochemical polarisation and EIS methods. The naturally oil was found to retard the corrosion rate of steel. The inhibition efficiency was found to increase with oil content to attain 80% at 2.76 g/L. PM oil acts as a cathodic inhibitor. The increase in temperature leads to an increase in the inhibition efficiency of the natural substance. The adsorption isotherm of natural product on the steel has been determined. © 2006 Elsevier B.V. All rights reserved.