Dissociation of Basic Dyes by Advanced Oxidation: Theoretical Study by DFT Calculations

Abstract

This work is based on a theoretical study concerning the degradation of basic dyes by advanced oxidation on five basic molecules called as follows: basic red 2 (BR2), basic red 5 (BR5), basic red (BR10), basic violet 5 (BV5) and basic violet 12 (BV12). The purpose of this work is to determine the attack sites most reactive to radical attacks. In other words, the location of the sites which favors the degradation by using the advanced oxidation process. This process is essential in the field of the water depollution. The work was done theoretically by ab initio methods. The calculations were carried out by CAM-B3LYP functional and 6-31++G(d, p) basis set. The exploitation of the results gives the following parameters: local indices of reactivities to radical attacks, global indices of reactivities and transition states. The results obtained from these parameters show the most reactive sites to radical attacks that are in good agreement with the sites determined experimentally. Hence, the majority of the sites were located at the level of the phenazine chromophore constituting the five dyes.