Inhibition of copper corrosion in acidic chloride pickling solutions by 5-(3-aminophenyl)-tetrazole as a corrosion inhibitor

Inhibition of copper corrosion in acidic chloride pickling (0.5 M HCl) solutions by 5-(3-Aminophenyl)-tetrazole (APT) as a corrosion inhibitor has been studied using potentiodynamic polarization, chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), weight-loss and Raman spectroscopy investigations. Electrochemical measurements showed that the presence of APT and the increase of its concentration significantly decrease the cathodic, anodic, and corrosion currents as well as corrosion rates. This effect also decreases the dissolution currents of copper at 200 mV vs. Ag/AgCl, and greatly increases surface and polarization resistances and inhibition efficiency as indicated by CA and EIS measurements. Weight-loss data revealed that the corrosion rate of copper decreases to a minimum and the inhibition efficiency increases to a maximum in the presence of APT and upon increasing of its concentration even after 72 h of copper coupons immersion. Comparing the Raman spectrum obtained on the copper surface after its immersion in HCl solution containing 1.0 mM APT for 72 h to the spectrum obtained for the solid APT alone indicated that APT molecules inhibit the corrosion of copper via their adsorption onto its surface.