Synthesis and Characterization of Phenolphthalein Derivatives, Detailed Theoretical DFT Computation/molecular Simulation, and Prevention of AA2024-T3 Corrosion in Medium 3.5% NaCl

Background: Aluminum alloy corrosion prevention is a significant problem in the industry. The development of an effective protection strategy is a popular research area. In this work, two organic inhibitors phenolphthalein (P1) and (3-oxo-1, 3-dihydroisobenzofuran-1,1-diyl)bis(4,1-phenylene) bis(4-methyl benzenesulfonate) (P2) were used in 3.5% NaCl medium for alloy AA2024-T3 corrosion mitigation. Corrosion inhibition behavior was investigated by a combination of experimental and theoretical studies. Methods: The surface morphology of AA2024-T3 has been identified by scanning electron microscopy coupled with Energy Dispersive X-Ray Spectroscopy (SEM/EDS), and Infrared spectroscopy (FT-IR) confirms the adsorption of functional groups on the surface of the aluminum alloy. Furthermore, the adsorption energies of P1 and P2 on Aluminium (111) interfaces were computed by Molecular Dynamics (MD), and quantum chemical computations (density functional theory, DFT) were chosen for obtaining basic electronic/atomic-scale details about the compound adsorption on target alloy aluminum and their active sites. Significant findings: The effect of two organic inhibitors phenolphthalein (P1) and (3-oxo-1, 3-dihydroisobenzo-furan-1,1-diyl)bis(4,1-phenylene) bis(4-methyl benzenesulfonate) (P2) on the corrosion protection of Aluminium alloy in 3.5% NaCl solution was examined using electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PPD) methods. The Total polarization resistance (RTot) increased, and the corrosion current density declined with the increasing inhibitor concentration. Inhibition efficiency revealed the maximum value of 85% for the P1 and 93% for P2 at 10-4 M, respectively. the two inhibitors were categorized as mixed-type inhibitors since they inhibited both cathodic and anodic corrosion.