Investigation of some Schiff base compounds containing disulfide bond as HCl corrosion inhibitors for mild steel

The inhibition performance of three Schiff bases containing disulfide bond as corrosion inhibitors for mild steel in 2.0 M HCl has been investigated by weight loss measurements, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization study showed that all the inhibitors are mixed type. The adsorption of inhibitors on mild steel surface was found to follow Langmuir adsorption isotherm and the adsorption isotherm parameters (Kads, ΔGads) were determined. Quantum chemical calculations were further applied to reveal the adsorption structure and explain the experimental results. Some samples of mild steel were examined by SEM.

Research highlights
► All studied Schiff bases are effective inhibitors for mild steel in 2.0 M HCl.
► The inhibition is accomplished by adsorption of molecules on the steel surface.
► Examined Schiff bases behave as mixed type inhibitor.
► Feed back bonds form between the Schiff bases and steel surface.
► Quantum chemical calculations were applied to explain the experimental results.