Experimental and Surface Characterization of Quinazoline and its Derivatives as Corrosion Inhibitors for Mild Steel in 1 N HCl

Abstract

Quinazoline (Qz), 2-Ethyl Quinazoline (2-E.Qz), and 2-Heptyl Quinazoline (2-H.Qz) 
were investigated as corrosion inhibitors for mild steel in 1 N HCl using gravimetric, 
electrochemical (potentiodynamic polarization, electrochemical impedance 
spectroscopy), and surface characterization by (SEM-EDX, contact angle) techniques. 
Inhibition efficiencies reached 79.31%, 88.50%, and 94.25% at 250 ppm for Qz, 2
E.Qz, and 2-H.Qz, respectively, with 2-H.Qz exhibiting superior performance due to 
enhanced physisorption via its heptyl substituent. Electrochemical analyses revealed 
mixed-type inhibition, with increased charge transfer resistance and reduced double
layer capacitance. SEM-EDX confirmed protective film formation, while contact 
angle measurements indicated a shift to hydrophobicity. Langmuir adsorption 
isotherms and negative Gibbs free energy values (-24.44 to -26.82 kJ/mol) supported 
physisorption. These findings highlight quinazoline derivatives as effective, eco
friendly inhibitors for mild steel protection in acidic environments, with potential 
applications in industrial corrosion mitigation.