SBA15-Fluconazole as a Protective Approach Against Mild Steel Corrosion: Synthesis, Characterization, and Computational Studies.

A SBA15-Fluconazole composite (SBA15-Flu) was prepared to formulate a self-healing coating for mild steel. The composite was obtained by dispersing SBA15 in a methanolic solution containing Fluconazole (Flu). The materials were characterized by using different techniques. Electrochemical impedance spectroscopy (EIS) was used for protective behavior evaluation of the coatings on mild steel substrates in an electrolytic solution prepared from sodium chloride and ammonium sulfate. The EIS results indicate that the inhibitor trapped in the SiO2 matrix is released when it comes into contact the aggressive solution, thus protecting the metal. To understand the inhibitor release mechanism, docking studies were used to model the SBA15-Flu complex, which allowed us to further determine polar and non-polar contributions to the binding free energy. An analysis of the electron density within the quantum theory of atoms in molecules and the non-covalent interaction index frameworks were also carried out for the most favorable models of SBA15-Flu. The results indicate that the liberation rate of the Flu molecules is mainly determined by the formation of strong O-H⋅⋅⋅O, O-H⋅⋅⋅N, and O-H⋅⋅⋅F hydrogen bonds.