Two 2,3-dihydroquinazolin-4(1H)-one derivatives as corrosion inhibitors with a newly evaluated scaffold for mild steel in acid medium: Electrochemical, surface characterization, and quantum chemical studies
Year: 2026
Type: article
Abstract: This study examines the corrosion inhibition performance of two derivatives of 2,3-dihydroquinazolin-4(1H)-one; ZB1 (2-phenyl-2,3-dihydroquinazolin-4(1H)-one) and ZB2 (2-(2-chlorophenyl)-2,3-dihydroquinazolin-4(1H)-one) on mild steel in 1.0 M HCl solution at 298 K. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were used to quantify the inhibition efficiency at different inhibitor concentrations. Surface characterization techniques, including atomic force microscopy (AFM), scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM/EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR), were employed to examine morphology and chemical interactions on the steel surface after immersion. Electrochemical results revealed a significant decrease in corrosion current density in the presence of both inhibitors, with maximum inhibition efficiencies reaching 86.2% and 95.2% for ZB1 and ZB2, respectively, at 10⁻³ M. Nyquist plots showed a gradual increase in charge transfer resistance and a decrease in double-layer capacitance as the inhibitor concentration increased, confirming the formation of a stable protective film at the metal/electrolyte interface. AFM analysis showed a significant reduction in surface roughness, from Ra = 171 nm for the blank to Ra = 70.54 nm in the presence of ZB2, while SEM/EDX and XRD analyses provided qualitative morphological evidence consistent with protective film formation and the suppression of iron oxide formation. Adsorption studies indicated that ZB1 and ZB2 follow the Langmuir adsorption isotherm, with ΔG°ads values of −44.67 and −46.41 kJ/mol for ZB1 and ZB2, respectively, confirming the spontaneous nature of the adsorption process. The apparent activation energies recorded in the inhibited solutions 32.13 and 44.80 kJ/mol for ZB1 and ZB2, respectively exceed that of the control solution (21.00 kJ/mol), indicating a physisorptive contribution to the adsorption mechanism. Taken together, the values of ΔG° ads and E a consistently indicate a mixed adsorption mechanism, in which physisorptive interactions and chemisorptive coordinate bonds jointly contribute to the stabilization of the protective inhibitory layer on the surface of mild steel. DFT calculations and Monte Carlo simulations corroborated the experimental results by elucidating the molecular interaction modes between the inhibitor molecules and the iron surface. Overall, ZB2 exhibited superior inhibitory performance compared to ZB1, attributed to the electron-withdrawing effect of the ortho-chloro substituent.
Source: Results in Engineering
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,940
OpenAlex ID: W7170135600