Evaluation of Fuji apple peel extract as a corrosion inhibitor for carbon steel in a saline medium

Abstract

The present study evaluated the activity of extract obtained from the peel of Fuji apples (Malus Domestica) harvested in the region of Valparaiso, Chile, as a potential corrosion inhibitor for carbon steel in a saline medium. The total phenol and flavonoid content in the extract was measured and its main components were identified using HPLC-MS. The inhibition efficiency of the extract was evaluated by mass loss measurements, Tafel polarisation curves and electrochemical impedance spectroscopy, obtaining an inhibition percentage of around 90% at a concentration of 1000 ppm of extract. Adsorption of the extract's components on the surface of the steel followed the Langmuir adsorption isotherm model, implying a physisorption mechanism based on thermodynamic parameters and from the ΔGads0 value, which was calculated at -15.16 KJ/mol. SEM was used to verify the presence of an organic layer on the steel, corroborating the adsorption of the organic components from the extract blocking active sites on the steel.