The Inhibitory Effect of Diethanolamine on Corrosion of Mild Steel in 0.5 M Sulphuric Acidic Medium

Abstract

The inhibitory effect of diethanolamine (DEA) on corrosion of mild steel in 0.5 M H 2 SO 4 was investigated by various corrosion monitoring techniques. Galvanostatic polarization study revealed that this compound is a very good inhibitor. The inhibition efficiency (I%) varies in the range of 88.7% to 55.3 % for a concentration range of 10 -3 M to 10 -7 M at 303 K, respectively. A study of corrosion potential (E corr ) reveals that DEA is a mixed type inhibitor. DEA inhibited mild steel corrosion due to physical adsorption of the inhibitor on the metal surface. The study at higher temperatures indicates that the inhibition efficiency decreases with the increase in temperature. The adsorption of DEA on the mild steel surface in 0.5 M H 2 SO 4 follows the Frumkin's adsorption isotherm. The results of potentiostatic polarization study revealed that DEA is a strong passivating additive. The results of infra red (IR) spectroscopy, scanning electron microscopy (SEM) and quantum chemical study supplement the results of the electrochemical techniques.