A Highly Efficient Supported TiO2 Photocatalyst for Wastewater Remediation in Continuous Flow

Although TiO2 materials have been extensively studied as photocatalysts, there is not any commercial TiO2- supported photocatalyst used for wastewater remediation. This fact set the goal to synthesize a new supported titanium dioxide photocatalyst which, besides being robust, also has a high reaction surface and a very efficient TiO2 shell thickness. Hence, we present a novel TiO2-supported photocatalyst composed of titania-covered glass wool (GW) fibers decorated with SiO2@TiO2 core-shell spheres. For optimizing the photocatalytic activity of this material, the surface of SiO2 microspheres, as well as, the highly mechanically resistant GW fibers, were covered by a robust titania layer of ca. 20-30 nm of thickness. This layer contains nanometric crystals, ca. 12 nm in size, linked to each other and to the surfaces of both SiO2 microspheres and GW. An exhaustive characterization of the physicochemical properties of this new SiO2-TiO2 composite was performed to confirm the Si-O-Ti linkage and the anatase crystal phase. The photocatalytic activity was initially evaluated in batch through the photo-degradation of Methylene Blue as a standard dye. Afterward, the addition of the new photocatalyst in a solid phase stationary (SPS) photoreactor coupled to a TOC detector allowed studying in situ the mineralization of the recalcitrant pollutant phenol under a continuous flow regime. Results revealed that the optimized TiO2 surface of the SiO2-TiO2 composite produced the complete mineralization of phenol in less than three minutes. Even more, it was demonstrated that this photocatalyst is suitable for the industrial scale-up of wastewater treatment because it does not leach titania, its reuse does not require filtration procedures, and it can be easily implemented in SPS photoreactors at plant scale. In this context, the new material could be a good starting point to prepare other supported photocatalysts for wastewater remediation.