Investigation of the Corrosion-Resistant Properties of Citrus Aurantium Essential Oil in 1 M HCl

The fresh peel essential oils of citrus aurantium from Eastern Morocco (Oujda) were analyzed by the gas chromatography and gas-chromatography–mass-spectrometry. The analyzed essential oil mainly consists of monoterpene hydrocarbons (54.38%) with limonene (52.67%) as the major constituent. The effect of addition of citrus aurantium essential oil on the corrosion of steel in a 1 M HCl solution was studied by the weight-loss measurements, potentiodynamic polarization, and the electrochemical impedance spectroscopy (EIS) measurements. The inhibition efficiency was found to increase with the inhibitor content to attain 95% (for 5 g/liter). The data obtained from the EIS studies were analyzed to determine the model inhibition process by using the appropriate equivalent circuit models. The inhibition efficiencies obtained by different methods are in good agreement. It was discovered that the adsorption of natural products on the steel surface obeys the Langmuir’s adsorption isotherm.