Investigating the potential of casein as a sustainable material in inhibiting the corrosion of aluminum in hydrochloric acid

Abstract In this study, the efficiency of casein in inhibiting the corrosion of aluminum in 0.1 M HCl was evaluated. Based on the weight loss data, increasing the amount of casein in the electrolyte from 50 to 500 ppm at 298 K decreased the corrosion rate of aluminum, for instance, from 2.53 to 0.58 g m −2 h −1 . It was also demonstrated that with casein, the activation energy of the corrosion phenomenon increased (e.g., from 6.52 kJ/mol without casein to 27.54 kJ/mol with 500 ppm casein). The electrochemical polarization studies illustrated that in the presence of 500 ppm casein, the corrosion current density remarkably decreased from 63.09 to 6.1 µA/cm 2 . This was compatible with the increase in the charge transfer resistance recorded by electrochemical impedance spectroscopy. Furthermore, the X‐ray photoelectron spectroscopy and atomic force microscopy techniques confirmed the adsorption of casein on the working electrodes, which caused an enhancement in the surface quality of the specimens.