A confirmatory study on the use of N-methyl-2-pyrrolidone (NMP) in the industrial field for cleaning metal molds and other objects, Corrosion Inhibition of C38 Carbon Steel In 1M HCl: Experimental and Theoretical Study

This study presents a comprehensive investigation of N-methyl-2-pyrrolidone (NMP) as a corrosion inhibitor for carbon steel (C38) in a 1.0 M HCl environment, using both theoretical and experimental approaches. To the best of our knowledge, this is the first time NMP has been studied for its anticorrosive properties. Electrochemical tests, conducted with an SP150 potentiostat and a three-electrode system, revealed that NMP effectively inhibits corrosion through cathodic protection. The adsorption of NMP onto the steel surface follows a Langmuir isotherm model, confirmed by both stationary and transient studies. The results showed a significant increase in polarization resistance, with a maximum inhibition efficiency of 76.82% at a concentration of 10⁻² M. Theoretical analysis using Density Functional Theory (DFT) indicated a substantial energy gap (Egap = 6.293 eV) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), validating the experimental findings. Molecular dynamics (MD) simulations further demonstrated the stable adsorption of NMP on the steel surface, with an adsorption energy of -606.103 kcal/mol. Additionally, Natural Bond Orbitals (NBO) analysis provided insights into the molecular interactions and bonding characteristics. Overall, these results confirm that NMP is an effective corrosion inhibitor for carbon steel, offering valuable insights into its adsorption mechanism and potential industrial applications.