Sustainable Corrosion Inhibition of Mild Steel in Hydrochloric Acid Using Extracts of Phaseolus Vulgaris and Vicia Faba

Abstract

The inhibitory effects of extracts from Phaseolus vulgaris and Vicia faba beans, obtained from boiled beans, on the corrosion of EN Fe37-3FN mild steel in a 0.5 M hydrochloric acid medium were meticulously investigated utilizing electrochemical techniques and Electrochemical Impedance Spectroscopy (EIS). The corrosion rate was observed to decrease by 40% upon the introduction of 20 mg/L of the Phaseolus vulgaris extract, with a notable reduction of 70% when the concentration was increased to 2 g/L and beyond. The Vicia faba extract, however, displayed a slightly inferior inhibitory performance, with corrosion rates diminishing by 20% at 20 mg/L and 60% at concentrations of 2 g/L and above. The adsorption of extract constituents onto the steel surface was found to conform to the Langmuir adsorption isotherm model, thereby facilitating the calculation of the sorption equilibrium constant and revealing that the adsorption was primarily physical in nature. These extracts, which are typically discarded by-products of bean cooking, have emerged as cost-effective, readily accessible, and environmentally benign alternatives for mitigating steel corrosion in acidic environments.