The role of some triazoles on the corrosion inhibition of C1020 steel and copper in a desalination descaling solution

The effect of molecular structure on the performance of three triazole derivatives namely benzotriazole (BZT), 5-methyl-1H-benzotriazole (5MBZT), and 3-amino-5-methylthio-1H-1,2,4, triazole (3AMT) as corrosion inhibitors for C1020 steel and pure copper in 2% hydrochloric acid (HCl), which simulate descaling process in a typical desalination plant was investigated. Electrochemical characterization such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), linear polarization resistance (LPR) techniques and theoretical simulations were utilized in this study. The electrochemical characterization results showed that the order of inhibition efficiencies for the inhibitors was a function of the type of metal, molecular structure, and immersion time. For instance, for C1020 steel, the order of inhibition efficiency using EIS data was 5MBZT (91.8%) > BZT (78.1%) > 3AMT (24.8%) after 24 h of immersion. On the other hand, for pure copper, the order of inhibition efficiency with the same EIS data was 3AMT (93.0%) > 5MBZT (92.1%) > BZT (90.4%) after 24 h of immersion indicating the role of different metallurgy on corrosion protection. The theoretical results provided molecular level insights on the nature and the active sites of the corrosion inhibiting species as well as the energetics of the adsorption process on steel and copper.