Inhibition of Armco iron corrosion in 1 M HCl medium using saponin: Experimental and computational studies

Abstract

There is a dire need in recent years for new eco-friendly compounds to combat the threat of metal corrosion. For this purpose, the present work was devoted to testing the saponin extracted from Gypsophila simonii plant which is a native species in Turkey as a corrosion inhibitor for Armco iron in 1 M HCl solution through Tafel extrapolation and linear polarization techniques, as well as theoretical approach for the evaluation of the inhibition efficiency at different temperatures. Corrosion current densities, percentage inhibition efficiencies, and surface coverage degrees have been determined. The results obtained showed that when the concentrations of saponin increased, corrosion rates decreased at all temperatures studied. However, the increase in temperatures resulted in a decrease in inhibition efficiency. It has been determined that saponin prevents the corrosion due to adsorption on the iron surface and obeys Langmuir isotherm, which has also been borne out by scanning electron microscopy and density functional theory studies.