Economical Way to Protect Mild Steel in Acidic Medium: Combined Experimental and Theoretical Studies

Abstract

Organic molecules are often considered to be the best way to protect a material from corrosion, but the synthesis process is very expensive. In the present work, the ethanol solvent was investigated as efficient inhibitor of the mild steel corrosion in a molar hydrochloric acid solution via several methods including polarization and, electrochemical impedance spectroscopy to evaluate the concentration effect of the studied compound. The result shows that ethanol as inhibitor protects mild steel against corrosion in an acidic solution with the inhibition efficiency of 84% at 10^–3 M concentration obtained by EIS method. The polarization curves data show the studied inhibitor to be of the mixt type. Also, a good correlation between the impedance and the Tafel curves data were observed. Various adsorption isotherm models were tested to elucidate the adsorption mechanism of ethanol. In addition, the scanning electron microscopy with energy dispersive X‑ray analysis was applied to confirm the adsorption of ethanol onto the surface of mild steel and its anti-corrosion effect by a formed protective layer. Also, this result was supported by theoretical studies such as the Monte Carlo simulations and the density functional theory.