Estimation of the Inhibition Efficiency of Polysorbate 80 Against the Corrosion of 6061 Aluminum Alloy in Di-Sodium Hydrogen Orthophosphate Solution

Abstract

Abstract The inhibiting behavior of polysorbate 80 on 6061 aluminum alloy corrosion was evaluated in 1.0 M Na2HPO4 solution. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used in this study. The obtained results showed that the inhibition efficiency increases by increasing the concentration of polysorbate 80 reaching 85.8% at 500 ppm. Good agreement was found between the results obtained from the two techniques used. The inhibition process was found to be due to adsorption of the organic compound on the alloy surface obeying the Langmuir isotherm. Polarization curves indicate that the inhibition of polysorbate 80 has the mixed anodic–cathodic nature. EIS exhibits one capacitive loop which is attributed to the double layer charging and the charge transfer process. The inhibition efficiency of polysorbate 80 decreased by rising the temperature in the range of 303–333 K. These results confirm the physisorption of the inhibitor molecules on the metal surface. The thermodynamic functions for the dissolution and adsorption processes were calculated and discussed.