Corrosion Inhibition of a Mixture Containing Imidazoline on Carbon Steel in Citric Acid Solution

The mixture of imidazoline and potassium iodide as a corrosion inhibitor for carbon steel in 4% (wt) citric acid solution was investigated by weight loss test and polarization curve methods. Results show that the combined inhibitor strongly inhibits the corrosion of 45# carbon steel in citric acid solution and the mixture with the mass ratio undecyl-N-carboxymethyl-hydroxyethy imidzoline (UHCI) :KI of 3:1 has the best corrosion inhibition at a total concentration of 0.4%. The polarization curves indicate that the combined inhibitor behaves as a mixed type inhibitor.