Estudo teórico da adsorção de triclosan em matriz de quitosana

Abstract

The compound Triclosan (TCS) is widely used in personal hygiene products and is commonly found in sanitary effluents. When these effluents are not treated properly, this contaminant can reach water resources and, consequently, pose risks to human health and the environment. Ingestion of TCS can cause problems such as metabolic imbalances, intestinal problems and liver tumors. A sustainable alternative for removing this contaminant is the use of adsorbent biopolymers, which are low-cost, renewable and biodegradable. One of the most promising biopolymers is chitosan (QT), which has excellent adsorptive properties due to the functional groups present in its structure. In this context, this study evaluated, through computational simulations, the interaction of the triclosan molecule with chitosan. The frontier molecular orbitals and electrostatic potential maps showed that different forms of interactions can occur, and thus, all complexes were stable after optimization of the interactions. The bond lengths of the interactions ranged from 1.839 Å to 3.606 Å and the interactions were mainly formed by hydrogen bonds where the interaction ranged from 1.839 Å to 2.822 Å. The distance of interactions between H...Cl ranged from 2.963 Å to 3.606 Å, and had Van der Waals where the interaction distances ranged from 2.593 Å to 3.143 Å. The binding energy allowed to infer that adsorption occurs (∆EBind < 0), in addition, the thermodynamic properties showed that the process is exothermic and that two complexes are spontaneous. The topological parameters generated by the quantum theory of atoms in molecules showed that almost all interactions between TCS-QT were electrostatic and the non-covalent interaction analysis ratified the presence of Van der Waals interactions between the complexes. Thus, it can be confirmed that the study demonstrated the efficiency of chitosan for the treatment of water and effluents contaminated by Triclosan.