The synergistic effect of 2-mercaptobenzotiazole and zinc nitrate as corrosion inhibitor on carbon steel in saline solution

In this study, the synergistic effects of 2-mercaptobenzotiazole molecules and zinc nitrate on the corrosion behavior of carbon steel were investigated using electrochemical techniques in 3.5% NaCl solution. The experimental results revealed that combination of 2-mercaptobenzoimidazole (MBT) and zinc nitrate with ratio of 100 ppm : 100 ppm, resulted in the least corrosion current (1.03 lA cm ) and the highest corrosion inhibition efficiency. Polarization results showed that the inhibition mechanism of inhibitor was mixed-type (anodic and cathodic mechanism) corrosion inhibition which was predominantly influenced by a reduction in dissolution rate of the substrate (decrease in anodic current density). Electrochemical impedance spectroscopy analysis yielded more accurate results about the formation mechanism and stability of the inhibitor film over prolonged time. The precipitation of chelate from inhibitor molecules and zinc cations on steel surface was found to be the main mechanism for increasing the corrosion resistance of steel substrate.