Corrosion inhibition of mild steel in acidic solution by Tagetes erecta (Marigold flower) extract as a green inhibitor

The extract of Tagetes erecta (Marigold flower) [TEE] has been evaluated as a corrosion inhibitor for mild steel in 0.5 M H2SO4 solution by means of gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopic measurements. Tafel polarization studies reveal that TEE acts as an efficient mixed inhibitor. The adsorption of the inhibitor on the mild steel (MS) surface follows the Langmuir adsorption isotherm, indicating monolayer adsorption. The activation parameters governing adsorption show that the inhibitor is physically adsorbed. The results of quantum chemical calculation indicate high feasibility of adsorption of molecular and protonated Lutein, a major component of TEE.