Electrochemical and Quantum Chemical Studies of 5-Substituted Tetrazoles as Corrosion Inhibitors for Copper in Aerated 0.5 M H 2 SO 4 Solution

Abstract

Two 5-substituted tetrazoles, 5-(2-thienyl)-1,2,3,4-tetrazole (2-THTT) and 5-(4-pyridyl)-1,2,3,4-tetrazole (4-PYTT), as copper corrosion inhibitors in aerated 0.5 M H2SO4 solution were studied by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical calculation. Polarization curves indicate that inhibition efficiencies of tetrazoles increase with increasing inhibitors concentration. The electrochemical results show that the inhibition efficiency of 2-THTT is higher than that of 4-PYTT. Inhibition efficiency of 2-THTT reached 98.9% at very low concentrations (0.25 mM) by EIS, which makes 2-THTT an efficient inhibitor in aerated 0.5 M H2SO4 solution. The adsorption of 5-substituted tetrazoles on copper surface obeys the Langmuir isotherm. All the computed quantum chemical parameters are found to correlate well with experimental inhibition efficiencies of inhibitors.