(163e) Influence of Secondary Heteroatoms within Aromatic Compounds on Corrosion Inhibition of Carbon Steel

Molecular structure and the chemical interactions of organic compounds with metal electrodes is critical to further exploration of corrosion inhibition mechanisms. In this regard, the number and nature of the heteroatom(s) in cyclic organic compounds is crucial to its effectiveness as an inhibitor. The impact these atoms have on the molecular orbitals and electronic density of the molecule vastly changes the interactions with a metal surface. Traditionally oxygen, nitrogen, and sulfur are the most common in organic inhibitor molecules and follow this order for inhibition efficiency. Benzothiazole, benzimidazole, benzoxazole, and indole were tested using cyclic potentiodynamic polarization as well as electrochemical impedance spectroscopy at three inhibitor concentrations as well as at four temperatures in one molar hydrochloric acid. The inhibition efficiency correlation with the included heteroatom was studied and the interactions with the surface were explored using DFT calculations in parallel with molecular dynamics simulations. It was found that addition of a second heteroatom follows the inhibition efficiency order traditionally seen but does not mean improved inhibition over a singular heteroatom.