Evaluation of Inhibition Efficiency of 1-(2-pyridylazo) -2- naphthol and Bromide Ion on the Corrosion of Mild Steel in Sulphuric Acid Solution

摘要

The corrosion inhibition of mild steel in 0.5 mol/L sulphuric acid solution by bromide ion in theabsence and presence of 1-(2-pyridylazo)-2-naphthol (PAN) has been studied by potentiodynamicpolarization, electrochemical impedance spectroscopy and weight loss. Potentiodynamic polarizationresearches show that single bromide ion or the complex of bromide ion and PAN acts as a mixed-typeinhibitor and do not change the mechanism of either hydrogen evolution reaction or metal dissolution.The charge transfer process controls the corrosion reaction. The studies reveal that the complex ofbromide ion and PAN shows a quite well inhibition and their synergistic effect was observed anddiscussed. The adsorption of the inhibitors on the steel surface obeys the Langmuir adsorptionisotherm. The thermodynamic parameters such as adsorptive equilibrium constant (Kads), adsorptiono o o free energy (G ads), adsorption heat (H ads) and adsorption entropy (S ads), kinetic data such asapparent activation energy (Ea) and pre-exponential factor (A) were calculated and discussed. Theo values of G ads indicate that the adsorption of the inhibitors on the mild steel surface in 0.5 mol/LH2SO4 solution is a mixed physical and chemical adsorption mechanism and the chemical adsorption isthe dominant in the presence of bromide ion and PAN together.