Electrochemical and theoretical studies of thienyl-substituted amino triazoles on corrosion inhibition of copper in 0.5 M H₂SO₄

2,5-Bis(2-thienyl)-4-amino-1,2,4-triazole (2-TAT) and 2,5-bis(3-thienyl)-4- amino-1,2,4-triazole (3-TAT) have been studied as inhibitors for the corrosion of copper in 0.5 M H₂SO₄ using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The inhibition efficiency of the triazole compounds increases with increasing concentration, and the effect of 3-TAT is better than that of 2-TAT with the same concentration. Potentiodynamic polarization measurements indicate the triazole compounds act as mixed type inhibitors in 0.5 M H₂SO₄. The adsorption of the triazole compounds is found to obey the Langmuir adsorption isotherm. High significant correlations for the triazole compounds are obtained between inhibition efficiency and quantum chemical parameters (R = 0.975) using the quantitative structure-activity relationship (QSAR) method.