Elimination of a mixture of two dyes by photocatalytic degradation based on TiO2 P-25 Degussa

The textile industry, which is a very large consumer of water, generates a very important pollution of the aqueous medium with discharges strongly contaminated by dyes. The treatment of these waters remains a major challenge especially for developing countries that doesn't yet have all the possibilities to integrate the concepts of sustainable development. Decontamination by conventional techniques is in some cases ineffective. Advanced oxidation techniques (AOPs), in particular heterogeneous photocatalysis, appear as methods of choice because they can give a total degradation of the pollutant. The present work aims to study the effectiveness of heterogeneous photocatalysis in the treatment of water containing either a dye or a mixture of dyes. Methyl orange and methylene blue were chosen as model molecules in this work. A systematic study of the adsorption of these molecules by the surface of the photocatalyst in the dark was carried out, as well as the kinetic study of the photodegradation of mixture of two dyes, shows that the reaction mechanism seems to follow the model of LANGMUIR-HINSHELWOOD (LH) where both pollutants compete. (C) 2019 Elsevier Ltd. All rights reserved.