2-Amino-5-ethyl-1,3,4-thiadiazole as a corrosion inhibitor for copper in 3.0% NaCl solutions

Abstract

2-Amino-5-ethyl-1,3,4-thiadiazole (AETDA) has been evaluated as a corrosion inhibitor for copper in 3.0% NaCl solutions using weight loss, pH, potentiodynamic polarization, potentiostatic current–time, and electrochemical impedance spectroscopic (EIS) measurements. The study was also complemented by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. Weight loss measurements gave an inhibition efficiency of about 60% with 1.0 × 10 −3 M AETDA present, increasing to about 97% at the AETDA concentration of 5.0 × 10 −3 M. Potentiodynamic polarization measurements showed that the presence of AETDA in de-aerated, aerated and oxygenated 3.0% NaCl solutions decreases cathodic, anodic, and corrosion currents to a great extent and shifts the corrosion potential slightly towards more negative values. Potentiostatic current–time measurements, SEM and EDX investigations also confirmed that the protection of the copper surface is achieved by strong adsorption of AETDA molecules. EIS measurements revealed that the surface and the charge transfer resistances increase upon increasing the AETDA concentration. Results together showed clearly that AETDA is a good mixed-type inhibitor for copper corrosion and its inhibition efficiency increases in the order of oxygenated > aerated > de-aerated 3.0% NaCl solutions.