Investigation on the Properties of Methyl 4-(((1-H benzo[d]imidazol-2-yl) methyl)thio)methyl)Benzoate on Aluminum Corrosion in Acidic Environment

Organic inhibitors are crucial for preserving metals from corrosion in acidic environments. In this regard, the methyl 4-(((1-H benzo[d]imidazol-2-yl)methyl)thio)methyl)benzoate (M-41HBI-2MTMB) was synthesized and investigated as an eco-friendly inhibitor for aluminum in a molar nitric acid solution (1 M HNO<sub>3</sub>). The gravimetric technique was used to study the inhibitory properties of the molecule, and the density functional theory (DFT) was conducted to elucidate the corrosion inhibition mechanism. The experimental data indicated that M-41HBI-2MTMB reduced the corrosion of the metal with a significant inhibition efficiency. The corrosion inhibition increased with an increase in the concentration of the molecule, reaching an efficiency of 98.5% at a concentration of 5.10<sup>-3</sup> M, and a temperature of 298 K. Adsorption isotherms and thermodynamic parameters were studied to elucidate the interactions between M-41HBI-2MTMB and the metal surface. The inhibitor adsorbed spontaneously onto the aluminum surface following the Villamil model (modified Langmuir isotherm). Additionally, the Gibbs free energy less than - 40 kJ.mol<sup>-1</sup> and the negative value of the enthalpy of adsorption suggested mixed-type adsorption with a predominance of physical interactions. The theoretical findings of DFT calculations revealed a positive fraction of electrons transferred (<i>ΔN = 0.247 eV</i>), a high value of the electrophilicity index (<i>ω = 3.807 eV</i>) as well as a low energy gap (<i>ΔE = 4.478 eV</i>) showing favorable interactions of M-41HBI-2MTMB with its environment. The active sites of the molecule were highlighted at the level of carbon atoms, and a corrosion inhibition mechanism was proposed.