Imidazolidiny Urea as a Potential Corrosion Inhibitor for Mild Steel in HCl Medium: Experimental and Density-Functional Based Tight-Binding Methods

This work focuses on the investigation of the inhibitory activity of imidazolidiny urea (IU) on mild steel in acidic environment by electrochemical and scanning electron microscopy (SEM) methods. The obtained results showed that adding IU to the corrosive medium significantly slows down the corrosion process, and the maximum inhibition efficiency can achieve 95% when the inhibitor concentration is 28 mM. The potentiodynamic polarization approach evidenced that IU is a mixed-type inhibitor and its adhesion on the substrate surface obeyed Langmuir adsorption isotherm. The SEM-EDS results show that a thin barrier film formed on the steel surface, which isolated the metal substrate from corrosive solution and then decoupled the cathodic & anodic corrosion processes. In addition, density-functional based tight-binding (DFTB) calculations were conducted to validate the inhibition mechanism. All obtained results ensure that the IU can control the corrosion process. This research provides a new candidate for environmental friendly corrosion inhibitors which has wide application prospect in the industry.