Résumé
Wastewater discharge from industries is a major environmental issue. Particularly, dyes are a major concern because of their toxicity on human health. Among the different techniques developed to remove these pollutants from water, heterogeneous photocatalysis appears as a promising technology, and it is one of the most studied for the decomposition of dyes in water phase over the few past decades.
Due to its properties, titania has been widely studied in the water treatment processes. However, to be implanted at a large scale, the photocatalytic activity still needs to be enhanced, especially in the visible domain. One way to reach this goal consists in increasing the specific surface area of the photocatalyst. From this point of view, porous TiO2 are excellent candidates to be considered in the water treatment technologies.
Here we review the use of porous titania-based nanomaterials for the photocatalytic degradation of dyes contained in wastewater, since this process is the most promising. First a short presentation of common dyes used in the industry and their classification is given. The main information concerning TiO2 as potential good photocatalyst for dye removal from wastewater is then given to remind its structures and properties, describe the mechanisms proposed for pollutant photodegradation, and present the parameters affecting its photoactivity efficiency. These aspects are the bases that orient researches in the synthesis of performant nanostructured TiO2 photocatalysts. Recent advances related to this topic are reviewed including the shaping and preparation of TiO2-based (nano)composites materials that have been developed to favor their use and/or integration in a process for potential industrial use. The last part is devoted to the progress of two most promising process for the implementation of viable system to remove dyes from wastewater at a large scale. Finally some patents and the interest of titania and photocatalysis in industry are reviewed.