Electrochemical and XPS studies of the corrosion inhibition of carbon steel in phosphoric acid pickling solutions by purpald

摘要

In continuation of our work on development of triazole derivatives as corrosionrninhibitors in acidic media, we have studied the corrosion inhibiting behaviour ofrnpurpad, namely 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT), on carbonrnsteel in phosphoric acid (2 M H_3PO_4) medium. In the present work, the corrosionrninhibition properties of purpald (AHMT)) on carbon steel in 2 M H_3PO_4 solution hasrnbeen examined and characterized by weight loss, electrochemical impedancernspectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) methods. Thernexperimental results reveal that the compound has a good inhibiting effect on therncarbon steel in 2 M H_3PO_4 solution. The adsorption of AHMT is found to obey thernLangmuir adsorption isotherm. Thermodynamic data and XPS analysis clearly showrnthat the adsorption mechanism of AHMT on carbon steel surface in 2 M H_3PO_4rnsolution is mainly electrostatic-adsorption. Data obtained from EIS studies werernanalyzed to model inhibition process through appropriate equivalent circuit model.