Coating of Al–X (X = Mg, Ga, Si) Alloys Nanosurface with Organic Corrosion Inhibitors Using TD-DFT Approach: Intra-Atomic and Interatomic Investigation through Langmuir Adsorption Study

The adsorption analysis of some organic inhibitors consisting of benzotriazole, 8-hydroxyquinoline, 2-mercaptobenzothiazole onto aluminum alloy surface based on optimized coordination of binding on the Al–X (Mg, Ga, Si) surface has been accomplished. In this work, the ONIOM approach has been performed with a three-layered level of high level of DFT method using EPR-III, 6-31+G(d,p) and LANL2DZ basis sets by the physico-chemical software of Gaussian 16 revision C.01 program, a medium semi-active part that includes important electronic contributions, and a low level part that has been handled using MM2 force field approaches. The physico-chemical properties of adsorption -surface complexes are one of the principal parameters for determining and choosing the Langmuir adsorption through IR, NMR, UV–Vis, HOMO/LUMO and charge distribution results. Comparing to $$\Delta G_{{{\text{ads}}}}^{^\circ }$$ amounts approved a good agreement among computed results, as well as the correctness of the selected isotherm for the adsorption process of benzotriazole → Al–Mg, benzotriazole → Al–Ga, benzotriazole → Al–Si, 8-hydroxyquinoline → Al–Mg, 8-hydroxyquinoline → Al–Ga, 8-hydroxyquinoline → Al–Si, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole → Al–Mg, 2-mercaptobenzothiazole → Al–Ga, and 2-mercaptobenzothiazole → Al–Si. Nuclear magnetic resonance has certainly has focused on the aluminum shielding in the intra-atomic interaction with magnesium, gallium and silicon and simultaneously interatomic interaction with other atoms in organic inhibitors through variety of high, medium and low layers of ONIOM method. Al–Si with highest fluctuation in the shielding tensors of NMR spectrum generated by intra-atomic interaction leads us to the most influence in the neighbor atoms generated by interatomic reaction. Moreover, based on the computed amounts of UV–Vis spectra for benzotriazole, 8-hydroxyquinoline and 2-mercaptobenzothiazole adsorb on the Al(111)-alloy surface, there are maximum adsorption bands between 200–280 nm for benzotriazole, 225–350 nm for 8-hydroxyquinoline and 210–280 nm for 2-mercaptobenzothiazole, respectively; and maximum adsorption bands for benzotriazole, 8-hydroxyquinoline, and 2-mercaptobenzothiazole has observed around 230, 300, and 240 nm, respectively.