A Combined Experimental and Theoretical Study on the Corrosion Inhibition and Adsorption Behaviour of Quinoxaline Derivative During Carbon Steel Corrosion in Hydrochloric Acid

Abstract

The corrosion inhibitive effects of 2-(4-methylphenyl)-1,4-dihydroquinoxaline (Q1) on carbon steel surface in hydrochloric acid solution was studied using weight loss measurements, electrochemical impedance spectroscopy (EIS), Tafel polarization techniques and quantum chemical approach, using the density functional theory (DFT). Inhibition efficiency increased with increase in concentration of the inhibitor. The degree of surface coverage of the adsorbed inhibitor was determined by weight loss technique, and it was found that the results obeyed Langmuir adsorption isotherm. Tafel polarization data indicated that this inhibitor is of mixed type. EIS shows that chargetransfer resistance increases and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. Trends in the calculated molecular properties (e.g., dipole moment, HOMO and LUMO energies) were compared with trends in the experimentally determined inhibition efficiency. The results show that trends in the quantum chemical descriptors are in agreement with the experimentally determined inhibition efficiencies.

Synthesis, characterization and electrochemical analysis of cysteine modified polymers for corrosion inhibition of mild steel in aqueous 1 M HCl

“…This could be because of the desorption of adsorbed copolymer, leading to a larger exposure of the metal to the acid solution, resulting in an increase in corrosion rate. 52,53 3.2.3 Impedance measurements. The EIS measurements were performed aer the immersion of mild steel in 1 M HCl for 45 min.…”

Heteroatoms and π electrons as favorable factors for efficient corrosion protection

“…The higher σ value indicates softer nature of the molecule and higher tendency to accept electrons to the metal . QSB2‐12 and QSB2‐18 are the softest molecules which indicates their tendency to accept electrons from the metal is higher than for the other inhibitors.…”

Corrosion inhibition of aluminum in biodiesel by ethanol extracts of Rosemary leaves

“…The value of regression coefficient R 2 (almost equal to unity) confirmed that the adsorption of Rosemary extract on the metal surface follows Langmuir adsorption isotherm. The slopes of straight lines are very close to unity, suggesting that adsorbed inhibitor molecules form monolayer on the metal surface and there is no interaction among the adsorbed inhibitor molecules [37]. between inhibitor molecules and metal surface [38].…”