Rotating cylinder electrode (RCE) methodology with electrochemical impedance spectroscopy (EIS)
measurement was applied to study the inhibition behavior of pyridine, quinoline and acridine on CO2
corrosion of X65 carbon steel. The inhibition performance of nitrogen heterocyclic aromatic compounds
was evaluated as a function of the number of rings (single/double/triple), salinity (0.1%, 1%, 10% wt.
NaCl), pH (4, 5, 6) and temperature (30°C, 50°C, 70°C). The chemical dosages were based on a series
of proportional Concentrations of Maximum adsorption (CMA) values determined from a parallel study
on Pt electrode, using a variety of other methodologies.
The results showed that acridine exhibits high inhibition efficiency while pyridine and quinoline exhibit no
inhibition at studied conditions. The concentration for maximum inhibition efficiency (CME) and Langmuir
adsorption constants (Kads) were obtained for acridine and compared with their corresponding CMA
values, as a function of pH, temperature and salinity.