A study of the gorse aqueous extract as a green corrosion inhibitor for mild steel in HCl aqueous solution

Abstract

The behavior of the gorse extract has been investigated as a new corrosion inhibitor by weight-loss measurements, potentiodynamic polarization curves, electrochemical impedance spectroscopy and scanning electron microscopy. Weight-loss measurements showed an increase in inhibition efficiency (IE) with the immersion time and the concentration of the extract. At 800 mg L−1, the extract IE ranged from 72.5% to 93.8% for 2 and 48 h, respectively. The Ea decreased slightly with the addition of the extract, characterizing the chemical adsorption by the molecules present in the extract on the surface. The measurements of electrochemical impedance spectroscopy showed an increase in Rct and a decrease in Cdl, reaching 96.6% of IE at 1600 mg L−1. The polarization curves indicated that the gorse extract served as an adsorption inhibitor, reducing both the anodic and cathodic current density. The high-molecular-weight fraction isolated from the gorse extract also showed high inhibition efficiencies.