Improvement of Corrosion Resistance of Carbon Steel in Hydrochloric Acid Medium by 3,6-bis (3-Pyridyl)Pyridazine

Abstract

Corrosion inhibition of carbon steel in normal hydrochloric acid solution at 30°C by new pirydazine derivative, namely 3,6-bis (3-pyridyl) pyridazine (3-PYP) has been studied by a series of known techniques such as weight loss, polarisation and electrochemical impedance spectroscopy (EIS). The experimental results have showed that this organic compound revealed a good corrosion inhibition and that the inhibition efficiency is increased with the inhibitor concentration. Potentiodynamic polarisation suggested that it is a mixed type of inhibitor. Two time constants determined by the charge-transfer and the adsorption of the inhibitor, respectively, can be readily outlined. The adsorption of 3-PYP on the carbon steel surface, in 1 M HCl solution, obeyed to the Temkin’s isotherm with a very high negative value of the standard Gibbs free energy of adsorption ∆ G°ads (chemisorption). Quantum chemical calculations and X-ray photoelectron spectroscopy (XPS) analysis were carried out to establish the mechanism of corrosion inhibition of carbon steel in 1 M HCl medium in the presence of 3,6-bis (3-pyridyl) pyridazine (3-PYP).