Potentiodynamic polarization measurements were conducted using a VoltaLab-PGZ-301 (France). A conventional cylindrical glass cell of 250 mL with three electrodes was used. A platinum sheet and saturated calomel electrode (SCE) were used as auxiliary and reference electrodes, respectively. The working electrode was cut in the form of disk (from the used carbon steel) with an area of 0.7 cm2 was embedded with epoxy except of the working surface area. Potentiodynamic polarization curves were obtained by varying the potential automatically from −1000 mV to −200 mV with the scan rate of 2 mV. The inhibition efficiency (η %) was calculated using Eq. (3) as follows [24]: