Effective corrosion inhibition of mild steel in acidic medium using inexpensive kermes natural dye: experimental and quantum chemical study.

Purpose The purpose of this paper is to test the Natural Kermes dye (NKD) as a cheap and stable corrosion inhibitor for mild steel in 1.0 M HCl and its adsorption mechanism on the steel surface.Design/methodology/approach The inhibition action of NKD was studied using AC impedance, potentiodynamic polarization, scanning electron microscope (SEM) and UV-visible spectra techniques complemented with quantum study.Findings Here, the authors show that addition of NKD inhibits effectively the corrosion of steel in HCl solution via its adsorption on the steel surface. The inhibition efficiency of NKD increases with increase in its concentration and decreases with temperature. Potentiodynamic results revealed that NKD acts as a mixed–type inhibitor. Thermodynamic parameters for corrosion and adsorption process were obtained from the experimental data. Moreover, the experimental inhibition efficiencies were correlated with the electronic properties of NKD using density functional theory.Originality/value To the best of the authors’ knowledge, this is the first report showing the effect of NKD on the corrosion inhibition of steel. [ABSTRACT FROM AUTHOR]