Dodecyl Amine Adsorption on the TiO2 (0 0 1) Surface and its Effect on the Surface Wettability: A molecular Dynamics Study

چکیده مقاله

The molecular adsorption of dodecyl amine (DDA) onto the TiO₂ (001) surface and its effects on wettability were studied using molecular dynamics (MD) simulations. The research focused on elucidating the microscopic mechanisms driving the transition from hydrophilic to hydrophobic surface behavior, critical for mineral flotation applications. Two systems were simulated: TiO₂-water and TiO₂-DDA-water, employing the ReaxFF force field to evaluate adsorption stability, density distribution, hydrogen bonding, and electrostatic interactions. Key findings demonstrated that DDA adsorption stabilized within 2.5 nanoseconds, as indicated by Root Mean Square Deviation (RMSD) trends. This adsorption altered surface wettability by significantly reducing surface energy. Density profile analysis showed that water molecule layering became less pronounced on the DDA-coated surface, with the density peak shifting from 2 Å to 6 Å. Hydrogen bonding analysis revealed a decrease in the average number of bonds per water molecule from 3.75 on the bare surface to 3.32 on the coated surface, reflecting weakened water-surface interactions. The center of mass (COM) of water molecules shifted from 5 Å to 12 Å due to reduced electrostatic forces and surface tension. These results highlight how DDA modifies surface properties by reducing electrostatic interactions and water structuring near the TiO₂ surface, driving a hydrophilic-to-hydrophobic transition. The findings provide actionable insights for optimizing flotation processes and tailoring surface interactions in mineral processing and other applications.

 Keywords:  Dodecyl amine (DDA), TiO₂ (001) surface, Molecular dynamics simulation, Surface wettability, Collector adsorption, Hydrophilic-to-hydrophobic transition