Corrosion Inhibition and Passivation Delay Action of Lauroamide Propylbetaine on Zinc in Alkaline Medium

The effects of lauroamide propylbetaine on zinc corrosion and passivation are investigated in 7.0 M KOH solution saturated with ZnO by Tafel polarization curve, electrochemical impedance spectroscopy and linear sweep voltammetry. It demonstrates that lauroamide propylbetaine acts as cathodic-type inhibitor and restrains zinc corrosion in alkaline medium through reducing the hydrogen evolution. With increasing concentrations of lauroamide propylbetaine, the corrosion inhibition effect and charge transfer resistance of zinc electrode enhance, and the corrosion inhibition efficiency reaches up to 84.1% in the presence of 800 ppm lauroamide propylbetaine. It is confirmed that the adsorption of lauroamide propylbetaine on the surface of zinc electrode follows Langmuir isotherm model. Besides, anodic polarization curves suggest that a small quantity of lauroamide propylbetaine is advantageous to delay the passivation of zinc electrode. Results reveal that the corrosion of zinc surface is alleviated in alkaline medium in the presence of 800 ppm lauroamide propylbetaine.