Abstract

Some quinazoline derivatives such as: 3-(4-chlorophenyl)-2-methylquinazolin-4(3H)-one (CMQ) and 2-methyl-3-(4-nitrophenyl) quinazolin-4(3H)-one (MNQ) were investigated as corrosion inhibitors for carbon steel in 2 M HCl solution. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, electrochemical frequency modulation and weight loss methods were used to study the inhibition action at 30°C. The corrosion of steel was controlled by a charge transfer process at the prevailing conditions. The electrochemical results showed that these compounds are efficient inhibitors for carbon steel and efficiency up to 93.8% was obtained at 30°C. The inhibition efficiency increases with inhibitor concentration. The adsorption of these compounds on carbon steel surface follows the Langmuir adsorption isotherm. Polarization curves indicate that investigated quinazoline derivatives are mixed-type inhibitors. The chemical and electrochemical methods gave similar results. 

Key words: Corrosion inhibitors, hydrogen acid (HCl), carbon steel, quinazoline derivatives.