Inhibition effect and theoretical investigation of dicarboxylic acid derivatives as corrosion inhibitor for aluminium alloy

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The corrosion inhibition ability of l-malic acid (MaA) and l-aspartate acid (AsA) against corrosion of the AA5052 alloy in 4 M sodium hydroxide–ethylene glycol solution is investigated. The presence of MaA and AsA in corrosion solution shows a remarkable inhibition of hydrogen evolution of the AA5052 alloy. AsA has the better inhibition effect for the self-corrosion of the AA5052 alloy and its max protection efficiency is 82.1%. This shows that the Mulliken charges of the nitrogen atom of the amine group on the AsA is lower than the Mulliken charge of the oxygen atom of the hydroxyl group on the MaA; the total Mulliken charge of AsA is lower than MaA, and AsA has a higher EHOMO and a lower energy gap, ΔN. The amine group and carboxyl group on the AsA is easier to coordinate with Al3+ ions to form a stable complex.