Aqueous extracts of olive roots, stems, and leaves as eco-friendly corrosion inhibitor for steel in 1 MHCl medium

Abstract

This work is devoted to examine the effectiveness of the aqueous extracts of olive (Olea europaea L.) leaves, roots, and stems on corrosion of mild steel in 1 M HCl solution using the weight loss measurement at various temperature and concentration effects. Polarization curves and electrochemical impedance spectroscopy (EIS) methods were employed to evaluate corrosion rate and inhibition efficiency. Corrosion inhibition efficiencies of 89.24, 88.84, and 89.83 % were achieved in 1 M HCl for olive root extract (ORE), olive stem extract (OSE), and olive leaf extract (OLE), respectively. It was found that the different extracts act as a good corrosion inhibitor for the tested system. The inhibitive action of the extract is discussed with a view to the adsorption of its components onto the steel surface which made a barrier to mass and charge transfer. The adsorption of extract components onto the steel surface was found to be a spontaneous process and increases the activation energy of the corrosion process. The inhibition efficiency is greatly reduced as the temperature increased. Experimental results show that corrosion inhibition efficiency increases with concentration of the sample extract. Polarization studies show that olive leaf, root, and stem extracts act as a mixed inhibitor.