Corrosion Inhibition of 2-Mercaptobenzimidazole and 1-Phenyl-5-mercapto-t etrazole for Copper in HCl Solution

The corrosion inhibition of 2 mercapto benzimidazole (MBI) and 1 phenyl 5 mercapto tetrazole (PMTA) for copper in 0.5mol/L HCl solution were investigated by weight loss measurements and electrochemical methods (potentiodynamic polarization and impedance spectroscope). Coupon tests show that the inhibition efficiency of MBI is 91.6% at 10 -3 mol/L level. Potentiodynamic polarization results reveal that the two compounds act as anodic inhibitors. Inhibition of the complex of MBI and PMTA was also studied. There is a synergistic effect for the best protection at the molar ratio of 1:2 between MBI and PMTA.