ADSORPTION PROCESS OF PESTICIDE ON SWCNT FUNCTIONALIZED AND CROSSLINKED WITH CHITOSAN USING PM3 SEMI-EMPIRICAL METHOD AND MONTE CARLO SIMULATION

In this work, using the PM3 semi-empirical method, the oxidation of the single-walled carbon nanotube (SWCNT) was studied by sulfuric and nitric acid for the incorporation of carbonyl (C=O), phenol (OH) and carboxylic (COOH) groups in the C=C bonds present on the surface of the nanotube. Subsequently, the crosslinking of the oxidized SWCNT (SWCNTox) and chitosan (Q) was observed through hydrogen bonds of the C=O and OH bonds with 2.34 Å, the process was endothermic and soluble in polar solvents due to the presence of OH and NH groups in the structure of SWCNTox/Q. The Monte Carlo modeling allowed to study the adsorption of pesticides in the SWCNTox/Q at different temperatures, where the QSAR (quantitative structure activity relationship) properties allowed predicting the behavior of the pesticides, that is, the degree of hydrophobicity (log P) and accessible surface area (ASA) were important parameters in the evaluation of SWCNTox/Q as an adsorbent and surface interacting with pesticides respectively. Finally, the adsorption was a physisorption process due to the electronegativity of the CO, OH, NH₂, NH and C=O bonds.

Keywords:
pesticides; adsorption; simulation.