Synthesis of Ni(II) and Cu(II) complexes with N-(benzylcarbamothioyl) benzamide as corrosion inhibitors for mild steel in 1M HCl

In this study, N-(benzylcarbamothioyl) benzamide(A1) with its Cu(II) and Ni(II) complexes were successfully synthesized using condensation method. The synthesized compounds were characterized by elemental analysis (CHNS), IR spectroscopy, NMR (1H) spectroscopy and melting point analysis. The synthesized compounds have been evaluated as new inhibitors for the corrosion of mild steel in 1M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Polarization measurements showed that these derivatives are anodic-type inhibitors. The inhibition efficiency of inhibitors increased with an increase the concentration of inhibitors. Nyquist plots showed depressed semicircles with their centre below real axis. From the results, it showed the inhibition efficiency of thiourea complexes were higher than the ligands due its larger size.