Experimental and theoretical research of three pyridine derivatives as corrosion inhibitors on steel in HCl acid solution

Purpose AQs3This study aims to explore the corrosion inhibition performance and mechanism of pyridine derivatives on the corrosion of N80 steel in a 0.5 M HCl solution using electrochemical experiments. Design/methodology/approach This study evaluates the corrosion performance of three pyridine derivatives (4-hydroxypyridine [OI], 4-aminopyridine [NI] and 4-mercaptopyridine [SI]) as organic corrosion inhibitors for mild steel in a 0.5 M HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and atomic force microscopy. The bonding mechanism between the reactive groups of the inhibitor molecules and the metal surface is analyzed using theoretical calculations. Findings The corrosion inhibition efficiency of the studied inhibitors on mild steel follows the sequence: SI > NI > OI. The bonding mechanism between the reactive groups of the inhibitor molecules and the metal surface is analyzed using theoretical calculations. It is found that the reactive group changes the charge transfer and the bonding strength of the corrosion inhibitor to the metal surface, which affects the corrosion inhibition performance. Originality/value This study provides valuable insights into the role of electron transfer in the interaction between the inhibitor and the metal surface, thereby contributing to the development and design of more effective and economical corrosion inhibitors.