Two ditetrazole derivatives as effective inhibitors for the corrosion of steel in CH3COOH solution

The inhibition performance of two ditetrazole derivatives of blue tetrazolium (BT) and nitrotetrazolium blue chloride (NTBC) on cold rolled steel (CRS) in 2.5 M CH3COOH solution was studied by weight loss, electrochemical techniques and scanning electron microscope (SEM). Quantum chemical calculations of BT2+ and NTB2+ were performed to theoretically investigate the adsorption mechanism. The results show that both BT and NTBC behave as effective inhibitors, and their maximum inhibition efficiency values are higher than 92% at 0.20 mM. The inhibition follows the order of NTBC > BT. The adsorption of either BT or NTBC on steel surface follows Langmuir isotherm. BT and NTBC can be arranged as mixed-type inhibitors. The presence of BT or NTBC increases the charge transfer resistance, and decreases the corrosion degree of steel surface in CH3COOH. The adsorption centers are mainly focused on two tetrazole rings as well as the linkers of two benzene rings.