STUDY ON CORROSION INHIBITION OF DISSYMMETRIC BIS-QUATERNARY AMMONIUM WITH IMIDAZOLINE RING

Abstract
Dissymmetric bis-quaternary ammonium with imidazoline ring was evaluated for corrosion inhibition efficiency against Q235 steel in 1.0 mol·L^-1 hydrochloric acid solution at room temperature by mass loss, potentio-dynamic polarization, electrochemical impedance spectrum (EIS) and scanning electron microscopy (SEM). The result of mass loss indicated that the inhibitory efficiency increases with increasing of the inhibitor concentration and is over 98% with addition of 50 mg·L^-1. Polarization data showed the compound acted as a cathodic inhibitor for Q235 steel and changing the anodic reaction progress in 1.0 mol·L^-1 hydrochloric acid solution. EIS results showed that the associated values of the charge transfer resistance (R_ct) increase by increasing the additive concentrations and immersing time whereas the associated values of double layer capacitance (C_dl) decrease. These changes in the impedance parameters (R_ct and C_dl) are indicative of adsorption of the compound on Q235 steel surface leading to the formation of a protective film. The relationship between molecular structure of the compound and the inhibition efficiency was investigated by PM6 quantum chemistry calculation. The obtained correlations and theoretical conclusions agree well with the experimental results.
Key words: Dissymmetric bis-quaternary ammonium; corrosion inhibitor; PM6 quantum chemistry calculations