Molecular dynamic and quantum chemical calculations for phthalazine derivatives as corrosion inhibitors of mild steel in 1 M HCl

The abilities of phthalazine derivatives, including phthalazine (PT), phthalazone (PTO) and phthalhydrazide (PTD), to inhibit the corrosion of mild steel in 1 M HCl at 30 °C were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Theoretical calculations were performed to investigate the electronic structures of the PT derivatives. Our results showed that the inhibition efficiencies of these derivatives improved with increases in concentration. The data also showed that PTD < PT < PTO in terms of the inhibiting efficiency. Theoretical calculations also revealed that PTO is expected to be the best inhibitor among the studied phthalazine derivatives.

► The inhibition of three phthalazine derivatives was studied. ► The inhibition efficiency increased in the following order: PTD < PT < PTO. ► The adsorption energies were calculated using molecular dynamics simulations. ► Quantum chemical parameters were calculated using the AM1, MNDO and PM3 methods. ► The adsorption of phthalazine derivatives obeys the Langmuir adsorption isotherm.