Amino Acids as Environmentally-Friendly Corrosion Inhibitors for 2024 Aluminium Alloy in Akaline Medium

The corrosion behavior of 2024 aluminium alloy was investigated in alkaline medium (pH=13) containing 0.6 mol.〖dm〗^(-3) NaCl in absence and presence of different concentrations of three amino acids separately [Methionine, Glutamice acid and Lysine] as environmentally friendly corrosion inhibitors over the temperature range (293-308)K. Electrochemical polarization method using potentiostatic technique was employed. The inhibition efficiency increased with an increase of the inhibitor concentration but decreased with increase in temperature . The maximum efficiency value was found with lysine =80.4 of 293 k and 〖10〗^(-2) mol.〖dm〗^(-3) concentration of lysine. The adsorption of the amino acids was found to obey Langmuir adsorption isotherm . Some thermodynamic parameter (〖∆G〗_ads ) and activation energy (E^* ) were calculated to demonstrate the mechanism of corrosion inhibition . The kinetic parameters were calculated using Arrhenius theory. Suitable mechanism was proposed for the corrosion of 2024 aluminium alloy in alkaline medium. The polarization measurements indicated that the inhibitor is of mixed type. The surface morphology of uninhibitied and inhibited samples were investigated using optical microscope.