Development of luminous textile for wastewater treatment by photocatalysis
Résumé
Photocatalysis, as an Advanced Oxidation Process (AOP), has a growing interest in the field of water treatment due to its complete mineralization of organic matter. Moreover this is an effective method easily combined with others technics communally used for water decontamination. Indeed photocatalysis can be used, either at first steps of decontamination process improving the biodegradability of pollutants, or at the end of water treatment plant to access a total mineralization of organic pollutants. But one of the main concerns with heterogeneous photocatalysis is the optimization of the interaction between reactant, catalyst and light irradiation. This interaction is essential to enable degradation reaction. In fact, photocatalyst, a semiconductor, has to be excited, thereby creating electron-hole pairs. For its part, reactant must be adsorbed on the catalyst surface in order to be mineralized by electron exchange reactions. In this study, an optical fiber fabric is developed by entrepreneurial collaboration in order to be used in aqueous phase, for water treatment. Thus by TiO2 deposition on this textile, the contact between photocatalyst and UV irradiation can be radically improved. Indeed the irradiation source is no more external but internal. First of all, an optical fiber fabric has been developed, choosing the method of weaving, optical fiber diameter and their density. Then textiles have been coated by different TiO2 suspensions before being characterized (by irradiance measurement, electronic microscopy, quantification of catalyst deposed on the textile surface). In parallel, measuring the optical fiber aging under continuous UVA irradiation, it is possible to demonstrate the dramatic destruction of the optical fibers cladding that induces a total inhomogeneous light dispersion at the textile surface. This problem is solved by depositing a SiO2 layer that prevents core auto degradation. SiO2 presents the advantage of non absorbing UV light. Thus the photocatalyst does not lose activity that has been demonstrated by reaction constants calculation.