Sweet Orange Peel Extract as green sustainable corrosion inhibitor for Al in 1 M HCl

In a one-molar hydrochloric acid solution, the potential of Sweet Orange Peel Extract (SOPE) as an inexpensive, efficient corrosion inhibitor for Al is explored. “Mass loss (ML), electrochemical frequency modulation (EFM)”, potentiodynamic polarization (PDP), “electrochemical impedance spectroscopy (EIS)”, energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques were used to study this. The findings show that when extract concentrations were raised the inhibitory efficiency (IE) of SOPE increased. On the other hand, the IE of SOPE decreased when raised the temperature of the system. A maximum inhibition efficiency of approximately 92.53 % was achieved for Al in 300 ppm HCl solution. The adsorption of SOPE onto the Al surface followed Langmuir adsorption kinetics, suggesting a mixed physical adsorption mechanism. The negative value of the free energy of adsorption, less than −20 kJ mol⁻¹, indicated the physical nature of the adsorption process. This study presents a powerful and environmentally friendly method to reduce electrochemical corrosion by utilizing a new, efficient inhibitor. Surface morphology was disclosed by various techniques both with and without SOPE. The outcomes obtained using all techniques are in good agreement.