Electrochemical and theoretical investigation of three novel quinazoline derivatives as corrosion inhibitors for mild steel in 1.0 M HCl acidic medium

Abstract

New quinazoline derivatives, Q-Cl, Q-N(CH₃)₂, and Q-NO₂, were synthesised and characterised by FT-IR. Their corrosion inhibition on mild steel in 1.0 M HCl at 298 was studied using electrochemical methods, SEM-EDX, DFT, and Monte Carlo simulations. All molecules showed excellent inhibition efficiencies of 99.38%, 99.91% and 91.65% for Q-Cl, Q-N(CH₃)₂, and Q-NO₂, respectively. Corrosion current densities decreased to 6µA·cm⁻² for Q-Cl, 50 µA·cm⁻² for Q-N(CH3)₂, and 82 µA·cm⁻² for Q-NO₂, confirming reduced corrosion rates. Increasing temperature (298–338 K) decreased efficiency. Activation and thermodynamic parameters indicated chemical adsorption dominated by chemisorption, confirmed by Langmuir's isotherm. The novelty lies in the synthesis of new quinazoline derivatives tested for the first time as corrosion inhibitors in 1.0 M HCl. Their donor and acceptor substituents near aromatic rings enhance electron density and strengthen steel interactions, achieving remarkable inhibition even at low concentrations. This study offers valuable insights into developing efficient structure-based corrosion inhibitors.