Gravimetric, electrochemical and quantum chemical studies of some pyridazine derivatives as corrosion inhibitors for mild steel in 1 M HCl solution

Abstract

The corrosion inhibition performances of three pyridazine derivatives, 6-methyl-4,5-dihydro-2H-pyridazine-3-one (MPYO), 6-phenyl-2H-pyridazine-3-one (PPYO) and 6-phenyl-2H-pyridazine-3-thione (PPYS) for mild steel in 1 M HCl solution were studied by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Some thermodynamic parameters were calculated and discussed. The effect of molecular structure on the inhibition efficiency was theoretically studied by density functional theory (DFT). Experimental and theoretical studies agreed well and confirmed that PPYS is the best corrosion inhibitor among the studied organic compounds which was related to the presence of a more favorable adsorption center of S atom in its molecular structure. © 2015 Taiwan Institute of Chemical Engineers.