Nickel-bipyridine-benzoic acid ternary complex: A new corrosion inhibitor for carbon steel in acidic medium

In this paper, nickel chloride was selected as metal ions and 2,2′-bipyridine (bipy) and benzoic acid (ba) as ligands to synthesize Ni-bipy-ba ternary complex. Its corrosion inhibition effects on the corrosion of P110 carbon steel in 0.5 M HCl were evaluated by weight loss test, electrochemical measurements, surface analyses, and theoretical calculations. The results show that the Ni-bipy-ba ternary complex exhibits excellent corrosion inhibition properties compared with the two ligands, especially at high temperatures, which is supported by the calculation of thermodynamic parameters. Surface analyses indicate that Ni-bipy-ba ternary complex can inhibit corrosion by forming adsorption film on the metal surface. Theoretical calculations show a good correlation with the experimental results. The best corrosion inhibition efficiency of Ni-bipy-ba ternary complex could be ascribed to the synergistic effect of metal ligands and the complex structure with larger dimension and molecular mass.