PM3 semi-empirical method and Monte Carlo simulation application on pesticides adsorption on SWCNT

The adsorption processes of glyphosate, diuron and atrazine on SWCNT were carried out using the PM3 semi-empirical method. Monte Carlo (MC) simulation using temperatures of 303.15, 313.15 and 323.15 K was applied to the analysis of the individual adsorption on the SWCNT, where a slight loss of Gibbs free energy and a positive heat of formation were appreciated, which were attributed to the non-planar geometry of the molecules and the sp. and sp2 hybridizations. On the other hand, the dipole moments decreased due to the influence of temperature on the electronic density and the distribution of charges. The formation of active sites allowed the increase of the surface area and volume. FTIR spectroscopy showed shifts in the pesticide/SWCNT crosslinking vibrations, attributed to the excitation of the electrons with increasing temperature. [Display omitted] •Gibbs free energy determined spontaneous and endothermic adsorption process of several pesticides on SWCNT surface.•Hydrophobic Log P was appreciated in the several individual adsorptions.•FTIR analysis showed the adsorption of glyphosate on the SWCNT, which was attributed to the crosslinking of the OH bond with the SWCNT. Meanwhile, the adsorption of diuron on SWCNT was attributed to the union of the hydrogen and the carbonyl group. Finally, the atrazine adsorption was appreciated between triazine group and carbon (π-π bonds) of SWCNT, respectively.•Monte Carlo simulation determined that pesticide/SWCNT adsorption was spontaneous, stable, and endothermic.•FTIR analysis showed some displacements due to the excited atoms caused greater vibration and therefore a change in their dipole moment.