New Green Anti-corrosion Inhibitor of Citrus Peels for Mild Steel in 1 M HCl: Experimental and Theoretical Approaches

The inhibitory effect of Moroccan Citrus Reticulata Peel’s essential oil (CREO) on the corrosion of mild steel (MS) in 1 M HCl, was assessed by weight loss measurements (WL), electrochemical studies such as potentiodynamic polarization (PDP and electrochemical impedance spectroscopy (EIS). Scanning electronic microscopy (SEM) coupled with energy-dispersive X-ray spectrometry (EDS) analysis was also employed. The major component was revealed by the gas chromatography–mass spectrometry (GC–MS) with Polarization curves revealed that this inhibitor acts as a mixed type inhibitor and the adsorption followed the Langmuir adsorption isotherm. The adsorption of tested inhibitor led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. The SEM/EDS results revealed the formation of a protective film on MS surface in the presence of a concentration of 900 ppm and with an efficiency up to 90.3%. Theoretical investigation revealed a strong and massive adsorption of d-limonene was approved by the value of Einteraction, which manifest with a negativity and the value of Ebinding, which manifest with a positivity.