Abstract
The inhibition performance of the 3-bromo-2-phenylimidazol[1,2- α] pyridine (BPP) on mild steel in normal hydrochloric acid medium (1 M HCl) at 298 K was tested by weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. This organic compound inhibits the acidic corrosion even at low concentration, reaching a value of inhibition efficiency up to 86% at a concentration of 10-3 M. The results obtained from the different corrosion evaluation techniques are in good agreement. Polarisation curves indicate that BPP is a mixed inhibitor, affecting both cathodic and anodic corrosion currents. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model. The adsorption of BPP on the steel surface, in 1 M HCl solution, obeys to Langmuir’s isotherm with a very high negative value of the free energy of adsorption ΔG°ads. The effect of the temperature on the corrosion behavior with addition of 10-3 M of the inhibitor was studied in the temperature range 298-328 K. Activation energies in the presence and absence of BPP were obtained by measuring the temperature dependence of the charge transfer resistance.