Synthesis, Corrosion Inhibition Efficiency and Adsorption Behavior of Dibenzo [a,c] Quinoxalino(2,3-I)Phenazine on Mild Steel in Acidic Medium

Abstract

Designing new inhibitors and understanding the mechanisms responsible for the inhibition are required in developing techniques to prevent corrosion. A new azaacene organic corrosion inhibitor, DQP (dibenzo[a,c]quinoxalino (2,3-i)phenazine), for mild steel in an acidic medium was successfully synthesized, characterized and reported for the first time using electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization measurement techniques (PDP). Surface morphologies and average percentage by weight of elements existing in mild steel were determined by SEM-EDX. The alterations in the impedance characteristics showed that DQP inhibitor adsorbed to the surface of mild steel, resulting in the creation of a protective coating. At the maximal concentration of 2.618 x 10-5 M, the inhibition efficiency reached 98.02% demonstrating DQP effectiveness in reducing corrosion process that may occur in mild steel in HCl. However, this efficiency is weakened by increase in temperature. The PDP curve revealed that DQP functions as a mixed inhibitor but is mostly cathodic. The adsorption behavior of DQP was best supported by the Langmuir adsorption isotherm (R2 = 0.9837) while the adsorption-free energy (G0ads) ranging from -41.749 to -43.183 kJmol-1 indicate chemical adsorption on metal surface. This study demonstrates that the synthesized DQP functions admirably well as a corrosion inhibitor in HCl solution.