Blue tetrazolium as a novel corrosion inhibitor for cold rolled steel in sulfuric acid solution

The inhibition effect of blue tetrazolium (BT) on the corrosion of cold rolled steel (CRS) in 1.0 M sulfuric acid (H2SO4) at 20 °C was investigated for the first time by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The results show that BT is a good inhibitor and the maximum inhibition efficiency is higher than 94% at 0.10 mM. The adsorption of BT on CRS surface obeys Langmuir adsorption isotherm. Polarization curves show that BT acts as a mixed-type inhibitor. EIS spectra consist of large capacitive loop at high frequencies followed by a small inductive one at low frequency values, and charge transfer resistance increases with the inhibitor concentration. The inhibitive mechanism is proposed from the viewpoint of adsorption theory.

► Blue tetrazolium (BT) is found to be a good inhibitor for the corrosion of CRS in 1.0 M H2SO4.
► BT acts as a mixed-type inhibitor, while prominently retards the anodic reaction.
► The adsorption of BT obeys Langmuir adsorption isotherm.
► EIS spectra exhibit large capacitive loop at high frequencies followed by a small inductive one at low frequency values. The addition of BT to 1.0 M H2SO4 solutions enhances Rt values while reduces Cdl values.