Corrosion inhibition of carbon steel by Vitex agnus castus leaves essential oils from the oasis of Tata

Abstract

The corrosion inhibition of carbon steel in 1.0 M HCl solution of essential oils of Vitex agnus castus leaves obtained by hydrodistillation was studied using: weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization. The inhibition efficiency of the carbon steel attaints more than 79% at the concentration of 1g/L. This efficiency reaches 81.05% and 80.95%¨with the EIS and potentiodynamic polarization tests were used respectively. Polarization curves reveal that Vitex agnus castus essential oils were a mixed type inhibitor. Changes in impedance parameters (charge transfer resistance, R_t, and double-layer capacitance, C_dl) were indicative of adsorption of Vitex agnus castus essential oils on the metal surface leading to the formation of a protective film. The effect of the temperature on the corrosion behavior with the addition of the optimal concentration of Vitex agnus castus essential oils was studied in the temperature range 298– 328 K.