Abstract
The corrosion protection of mild steel in 1 M HCl and 0.5 M H2SO4 solutions by ethanol extract of Vernonia amygdalina (VA) was studied using a combination of experimental and computational methods. The obtained results revealed that VA reduced the corrosion of mild steel in both environments and inhibition efficiency increased with VA concentration but decreased with prolonged exposure. Electrochemical results showed that the extract functioned via mixed corrosion inhibiting mechanism by adsorption of some organic constituents of the extract on the metal/acid interface. Findings from infrared spectroscopy and electron microscopy all confirmed that VA retarded mild steel corrosion in both 1 M HCl and 0.5 M H2SO4 through an adsorption process. The adsorption behavior of selected constituents of the extract was modeled using density functional theory computations.