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/cm². 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.