Three pyrazine derivatives as corrosion inhibitors for steel in 1.0 M H2SO4 solution

The inhibition effect of three pyrazine derivatives of 2-methylpyrazine (MP), 2-aminopyrazine (AP) and 2-amino-5-bromopyrazine (ABP) on the corrosion of cold rolled steel (CRS) in 1.0 M H2SO4 solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that all pyrazine compounds are good inhibitors, and inhibition efficiency follows the order: ABP > AP > MP. The adsorption of each inhibitor on CRS surface obeys Langmuir adsorption isotherm. For all these pyrazine derivatives, they act as mixed-type inhibitors. The probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.

► 2-methylpyrazine, 2-aminopyrazine and 2-amino-5-bromopyrazine (ABP) act as good inhibitors.
► The inhibition efficiency follows the order: ABP > AP > MP.
► The adsorption of each pyrazine inhibitor on steel surface obeys Langmuir adsorption isotherm.
► The pyrazine derivatives behave as mixed-type inhibitors.