Anticorrosion properties of 5,5′-dithiobis-(2-nitrobenzoic acid) and sodium sulfite compounds for aluminum alloy 2024-T3 in saline solution: Electrochemical, characterization and theoretical investigations

Abstract

Abstract The corrosion inhibition of aluminum alloy 2024-T3 by two organic compounds, 5,5′-dithiobis-(2-nitrobenzoic acid) (ER) and sodium sulfite (SUL), in 3.5% NaCl is investigated at various temperatures using electrochemical techniques, such as impedance spectroscopy (EIS) and potentiodynamic polarization. The polarization curves indicate that the inhibitors tested acted as cathodic inhibitors. The inhibition efficiency (IE %) increased with increasing inhibitor concentration to 93% at 10−2\u202fM ER and 98% at 5.10−3\u202fM of SUL. Moreover, adsorption of the compound on the surface of aluminum in 3.5% NaCl follows the Langmuir isotherm model. Data obtained from EIS studies are analyzed to model the interface of the metal/solution through appropriate equivalent circuit models. We study the temperature effect on the corrosion behavior of the aluminum alloy in 3.5% NaCl with and without the inhibitors. The adsorption free energy and activation parameters of the aluminum dissolution reaction in the presence of ER and SUL are determined. The results of SEM-EDS analyses support the adsorption inhibition mechanism. DFT using B3LYP/6-311G (d,p) is also performed in order to determine the correlation between the corrosion inhibition properties of the examined derivatives and their molecular structures. The adsorption of the compounds is confirmed by MD simulations. The experimental results support the theoretical outcomes.