Molecular Dynamics Simulation and Quantum Chemical Calculations for the Adsorption of some Thiosemicarbazone (TSC) Derivatives on Mild Steel

The adsorption mechanism and inhibition performance of some thiosemicarbazone (TSC) derivatives [2-acetylpyridine thiosemicarbazone (2APTSC), 2-acetylpyridine-(4-methylthiosemicarbazone) (2AP4MTSC), 2-acetyl-pyridine-(4-phenylthiosemicarbazone) (2AP4PTSC), 2-acetylpyridine-(4-phenyl-iso-methylthiosemicarbazone) (2AP4PIMTSC) and 2-acetylpyridine-(4-phenyl-isoethylthiosemicarbazone) (2AP4PIETSC)] on mild steel at temperatures ranging from 298 K to 333 K have been studied using molecular dynamics (MD) simulation and quantum chemical computational methods. The results obtained revealed that these molecules could effectively adsorb on Fe (001) surface and the active adsorption sites of these molecules are the thiocarbonyl sulphur atoms, nitrogen atoms and special negatively charged carbon atoms. All the inhibitors studied had unique corrosion inhibition performance with AP4PIETSC showing the highest inhibition performance at lower temperature ranges of 298 K to 313 K and 2AP4PIETSC displaying the highest inhibition performance at higher temperature ranges of 323 K and 333 K. Physical adsorption mechanism was observed for all the inhibitors studied.