Theoretical and experimental study of Imidazolium Ionic Liquid Effect on the Corrosion Inhibition of 316-Stainless Steel, Using Electrochemical Test Methods and Quantum Mechanics Theories

In this study, the impact of )1-Buthyl-3-methyl imidazoloum hexa fluorophosphatesas( a new inhibitor on the corrosion of stainless steel 316L (SS) in HCl solution was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Also, the absorption of inhibitor onto the SS surface followed the Langmuir absorption model with the free energy of absorption ΔG0adsof -8.57 kJ mol-1.
In addition, using density function theory (DFT) and atoms-in-molecule (AIM) theories, introduced by Richard Bader, which is a generalization of quantum theory to proper nano-size and molecular systems, the electronic organic-structure and local charge/energy transfer in the imidazole molecular system (as a organic-corrosion inhibitor element) are studied. In the same vein, the atomic electronic properties (such as electron density and its Laplacian), and the HOMO–LUMO gap (HLG) of this organic-molecular system are calculated. The results of the investigation show that proposed compound, as a commodious/economical -green inhibitor, has excellent inhibiting properties for SS corrosion in acidic solution. Furthermore, quantum mechanical results show that nitrogen atoms play domain role in intra-molecular charge and energy transfer (and thus electrochemical mechanism) in this inhibitor.