The study of the methanolic extract of “Pelargonium gravelons” as a green corrosion inhibitor of mild steel in H2SO4 0.5 M

Abstract

The purpose of our research is to determine the efficiency of “Pelargonium gravelons” (PGE) extract as green corrosion inhibitor of mild steel in an acidic medium (H2SO4 0.5 M). After the plant harvest and preparation, we extracted the phenolic compounds using methanolic solution, and in order to identify their chemical composition we used gas chromatography–mass spectrometry and Fourier transform infrared spectrometer. Later the electrochemical impedance spectroscopy (EIS) method and Tafel polarization method, bode tracings were used to determine the corrosion inhibition efficiency of our studied extract at different concentration range (25 ppm–50 ppm-100 ppm-200 ppm) and a temperature range of 298 K to 328 K, and for the work electrode which is mild steel we used scanning electron microscopy (SEM-EDX). The results show that the inhibitory efficiency of our extract increases with increasing concentrations to reach 96.2% in a concentration of 200 ppm. The adsorption properties of the PGE extract were investigated using Langmuir isotherm model, also the inhibition mechanisms, assessed on the basis of inhibition potency, temperature, kinetic and activation parameters, show that the plant extract has a mixed cathodic inhibition mechanism.