Influence of the Methylene Blue Dye (MBD) on the corrosion inhibition of mild steel in 0.5 M sulphuric acid, Part I: weight loss and electrochemical studies

The inhibition effect of methylene blue dye (MBD) on the corrosion of mild steel in 0.5 M sulphuric acid solution at 30°C was studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The results show that MBD is an excellent inhibitor even with very low concentration, and the adsorption of methylene blue dye (MBD) on the mild steel surface obeys Langmuir adsorption isotherm. Potentiodynamic polarization curves reveal that MBD behaves as a mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. Some thermodynamic functions of dissolution and adsorption processes were also determined. The obtained results indicated that MBD is chemically adsorbed on the steel surface.