The inhibition effect of Diantipyrylmethane (DAM) and its synergistic effect with potassium thiocyanate (KSCN) on mild steel corrosion in 1 M HCl solution were investigated by electrochemical methods, gravimetric analysis and scanning electron microscopy (SEM). The experiment results show that the inhibition efficiency increases with the concentration of DAM alone and increases further with the presence of 2 mM KSCN. The synergism parameters demonstrate that DAM cation has a significant synergistic effect with thiocyanate anion, which is agree with the corresponding thermodynamic and kinetic parameters. The results of quantum chemical calculation confirm that the dication structure of DAM molecule in acid medium plays a vital role during corrosion inhibition of mild steel.
The corrosion inhibition performances of Diantipyrylmethane (DAM) for mild steel in 0.5 M H 2 SO 4 were investigated using weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscope (SEM) and quantum chemical calculation. The obtained results reveal that DAM acts as a mixed-type inhibitor with a predominantly anodic reaction, and the inhibition efficiency increases with increasing inhibitor concentration whereas decreases with increasing temperature. The adsorption of DAM on steel surface is found to obey Langmuir isotherm, and the adsorption mechanism is mixed physical and chemical adsorption. The results of quantum chemical calculation demonstrate that pyrazolone rings within molecular structure of DAM play a dominant role in corrosion inhibition of mild steel.