Electrochemical evaluation of the anticorrosive potential of Anacardium occidentale extract on ABNT 1020 carbon steel in saline medium

Abstract

This study evaluated the anticorrosive potential of Anacardium occidentale Linn. bark extract applied to ABNT 1020 carbon steel in a saline medium (3.5 wt.% NaCl). Gravimetric mass loss tests and electrochemical analyses by potentiodynamic polarization were carried out in the absence and presence of the plant extract at different concentrations. Immersion test results demonstrated that the addition of 500 ppm of the extract promoted a significant reduction in mass loss and corrosion rate of the steel over an exposure period of 9 days. Polarization curves showed a systematic shift of the cathodic branches toward lower current densities with increasing extract concentration, resulting in a decrease in corrosion current density (J₍corr₎) from 2.45 × 10⁻⁵ A·cm⁻² in the uninhibited condition to 0.95 × 10⁻⁵ A·cm⁻² in the presence of 700 ppm of the extract. Inhibition efficiency increased proportionally with extract concentration, reaching values above 60%. The results indicate that Anacardium occidentale extract acts as a predominantly cathodic corrosion inhibitor through adsorption mechanisms at the metal/electrolyte interface, representing a sustainable and environmentally friendly alternative for the protection of carbon steels in aggressive environments.