Synthesis of New Benzotriazole Derivatives Containing Carbon Chains as the Corrosion Inhibitors for Copper in Sodium Chloride Solution

In this study, a series of benzotriazole derivatives with various carbon chains ( n = 1, 3, 4, 6, 7, 9, 10, 12, 16) were synthesized for the corrosion inhibition of copper in 3.5 wt % (wt %) NaCl solution. The corrosion inhibition efficiencies of these inhibitors in 3.5 wt % NaCl solution for copper were measured by various measurements including the polarization curves, the electrochemical impendence spectroscopy as well as the weight loss method. The inhibition mechanism of these new target molecules were analyzed by the plots of Tafel, Nyquist, and Bode. The corrosion inhibition effect was also evaluated by scanning the copper surface with an electron microscope. The results show that the corrosion of copper in chloride aqueous solution is efficiently inhibited by these new organic inhibitors. Furthermore, the corrosion inhibition efficiencies of the target inhibitors are shown to have much dependence on the carbon chain length attached to the molecular backbone. The inhibitor carrying a 7-carbon chain displays the greatest inhibition efficiency as large as ∼98% at 0.15 mM, while even the poorest inhibitor containing a 2-carbon chain shows ∼60% inhibition efficiency. The adsorption of these new inhibitors on copper was further revealed by analysis of Langmuir isotherms and quantum chemical calculations.