Inhibitive action of gramine towards corrosion of mild steel in deaerated 1.0 M hydrochloric acid solutions

The effect of addition of gramine on mild steel dissolution in deaerated 1.0 M hydrochloric acid was studied through potentiodynamic polarisation curves, electrochemical impedance spectroscopy and gravimetric measurements in the temperature range from 25 °C to 55 °C. Gramine was found to shift the corrosion potentials towards less noble values and decrease both dissolution of mild steel and hydrogen evolution reaction. Gramine did not affect the corrosion reaction mechanism (blocking effect). Results obtained from the several measurement techniques were in good agreement and revealed good inhibition efficiencies in the concentration range (0.75 mM ÷ 7.5 mM) particularly at higher concentrations.

► The addition of gramine to 1.0 M HCl effectively reduced the mild steel corrosion. ► The compound acted as a mixed-type inhibitor and obeyed Langmuir’s isotherm. ► Gramine adsorbed on the mild steel-solution interface by Cl- ions bridge.