Synergistic inhibition effect of 6-benzylaminopurine and iodide ion on the corrosion of cold rolled steel in H3PO4 solution

The synergistic inhibition effect of 6-benzylaminopurine (BAP) and iodide ion (I−) on the corrosion of cold rolled steel (CRS) in 1.0 M H3PO4 solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that BAP has a moderate inhibitive effect. However, incorporation of BAP with I− improves the inhibition performance significantly. The adsorption of BAP in the absence and presence of I− obeys Langmuir adsorption isotherm. BAP and BAP/I− mixture act as mixed-type inhibitors. A probable synergism mechanism is proposed.

► There is a synergistic inhibition effect of BAP and I− for steel in H3PO4 solution.
► The values of synergism parameter are higher than unity.
► The adsorption of BAP without and with 0.1 mM I− obeys Langmuir adsorption isotherm.
► The presence of I− contributes to increase adsorption of BAP.
► Individual BAP and the BAP/I− mixture behave as a mixed-type inhibitors.