Animal glue as green inhibitor for corrosion of aluminum and aluminum-silicon alloys in sodium hydroxide solutions

The inhibition effect of animal glue toward the corrosion of aluminum and two aluminum-silicon alloys in 0.1 M NaOH solution was investigated using potentiostatic polarization, electrochemical impedance spectroscopy (EIS), cyclic voltammetry and potentiodynamic anodic polarization techniques. The percentage inhibition efficiency increases with increasing concentration of animal glue and decreases with increasing temperature as well as Si content. The inhibiting effect of animal glue is due to the adsorption on the Al and two AlSi alloys surface. The adsorption process follows Langmuir isotherm. Polarization curves revealed that the studied inhibitor acts as a mixed type inhibitor mainly cathodic. The effect of rising temperature on the inhibition efficiency was studied and the values of activation thermodynamic parameters were computed and explained. It was found that the animal glue provides a good protection to Al and AlSi alloys against pitting corrosion by shifting the pitting potential to more noble direction. Results obtained from all electrochemical techniques were consistent with each other.