Dissymmetric bis-quaternary ammonium with imidazoline ring was studied for inhibition
behavior 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 inhibition efficiency
increased with the increase in inhibitor concentration and was over 98 % with the addition of
50 mg·L-1 inhibitor. Polarization data showed that the compound acted as a cathodic inhibitor
for Q235 steel by changing the OCP to more negative value and changing the anodic
reaction progress in 1.0 mol·L-1 hydrochloric acid solution according to the double of ba. EIS
results showed that the associated values of the charge transfer resistance (Rct) increased
with increasing inhibitor concentrations and immersing time whereas the associated values
of double layer capacitance (Cdl) decreased. These changes in the impedance parameters
(Rct and Cdl) were 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 correlations and theoretical conclusions were in good harmony with the
experimental results.
Key words: Dissymmetric bis-quaternary ammonium, corrosion inhibitor, PM6 quantum
chemistry calculations