Development of methods for the treatment of an indigo carmine dye in textile effluents

Résumé

The objective of this study is to treat the colored waste water loaded with an indigo carmine (IC) dye from the jeans processing of a textile factory in Antananarivo. We have developed simple, practical and inexpensive methods. Irradiation of the dye by natural and artificial light was carried out in the presence of a non-fixed TiO₂ catalyst. The molecule was then oxidized by a strong oxidant, sodium hypochlorite (NaClO). Experience shows that the mineralization of IC by sunlight is long even with a catalyst. But with an artificial light (CT: 4200K), the degradation of the IC follows the kinetics of order zero «0» with a constant k = 2.12 µmol L^-1h^-1. The half-life is obtained after 9.3h. By oxidation by hypochlorite, the discolouration is instantaneous.  The molecule is completely destroyed from a concentration of 400µM (ClO^-).  The methods we have studied are applicable for high-volume treatment, and reduce the risk of pollution of the ecosystem and the environment.