Computational Insights into Biomass-Derived Corrosion Inhibitors: DFT and Monte Carlo Simulation Studies on Aspirin, Paracetamol, Caffeine, and Ibuprofen.

Corrosion causes significant economic and environmental damage; hence, sustainable corrosion inhibitors are critical. The goal of this work was to look at the relationship between the gas and aqueous phases of Inhibitors of Biomass Corrosion: Aspirin, Paracetamol, Caffeine, and Ibuprofen compounds using the density functional theory (DFT), B3LYP/6-311G + + (d,p) basis set. Monte Carlo simulations were also conducted to demonstrate the adsorption of the examined substance on the Fe (110) surface, with an energy of 1 0 − 5 kcal/mol, using a total of 90 000 steps per iteration. Monte Carlo simulations were also conducted to demonstrate the adsorption on the Fe (110) surface, with an energy of 1 0 − 5 kcal/mol, using a total of 90 000 steps per iteration. This characteristic classifies Aspirin as a soft molecule (7.379378 eV − 1 ); the smallest energy gap 0.271026 eV enhances its performance as a corrosion inhibitor. Softer molecules like Aspirin are more reactive than harder ones such as Ibuprofen (2.3465 eV) because they have a greater ability to donate electrons to an acceptor. The Aspirin compound exhibits highest negative value of electrons transfer integral ( t e ) in both phases (− 1. 1 0 8 5 6), and (− 9. 0 1 3 3 7) indicate the best corrosion resistance, and good molecule-to-metal electron charge transfer. The Monte Carlo simulations predicted that among the studied molecules, the adsorption energy of Caffeine (− 1 2 4. 2 2 kcal/mol) can be attributed to its multiple nitrogen atoms capable of forming H-bonds with surface O–H groups, as well as its planar structure enabling π -electron interactions with the metal surface. Therefore, despite Aspirin's favorable values suggesting good electronic interaction, Caffeine would be considered the superior corrosion inhibitor overall because of its much stronger and stable adsorption onto the metal surface. [ABSTRACT FROM AUTHOR]