Synthesis, characterization and anti-corrosion properties of two new Schiff bases derived from diamino diphenyl ether on carbon steel X48 in 1M HCl

The corrosion inhibition effect of di[(4-phenylimino)-4-diethyl salicylaldehyde] ether (L1) and di[(4-phenylimino)-2,6-diacetyl pyridine] ether (L2) as Schiff bases on carbon steel X48 in 1 M HCl were examined with gravimetric measurement, Tafel polarization and electrochemical impedance spectroscopy (EIS). It was observed that the two compoundsL1andL2act as greatly corrosion inhibitors. The potentiodynamic polarization results indicate that they act as anodic and cathodic type. The adsorption of each inhibitor on the mild steel surface obeys Langmuir isotherm. The associated activation parameters together with the thermodynamic data are evaluated and discussed. The characterization of the adsorbed molecules (L1andL2) formed on the metal surface was carried out by SEM and AFM. The improvement in corrosion resistance was related to the presence of different substituent groups, apparently due to the easiness of the electron acceptance as confirmed by the quantum chemical calculations. Additionally, the molecular dynamic simulations were used to clarify the inhibition mechanism, especially, the adsorption modes and configurations of the studied inhibitor molecules.