Paper Published: Porous Silica Microspheres with Immobilized Titania Nanoparticles for In-Flow Solar-Driven Purification of Wastewater

A paper by Ana C. Marques et al. was published at the journal Global Challenges (open source) in May 2021, which deals with the development of a new support material having immobilized titania nanoparticles to be used in a continuous flow reactor. This engineered system enables the purification of wastewater through solar-driven photocatalysis. The work was done in collaboration with the MFM group of ETH-Zurich (Switzerland).

The establishment of interconnected macroporosity within inorganic silica microspheres makes them attractive for many applications. In this paper, published in open source, we test these microspheres as a platform for designing robust and efficient photocatalytic systems for a continuous flow reactor, enabling the purification of wastewater through solar-driven photocatalysis. The photocatalytically active microspheres are prepared by wet impregnation of porous silica scaffolds with Trizma®-functionalized anatase TiO2 nanoparticles (NPs). A comprehensive characterization of the individual TiO2 NPs, SiO2 microspheres and composite microspheres is performed. NPs loading of 22 wt% is obtained in the form of a thin and well-attached layer, covering the external surface of the inorganic silica microspheres as well as the internal surface of the pores. The TiO2 loading leads to an increase of the specific surface area by 26%, without impacting the typically interconnected macroporosity (ca. 60%) of the microspheres, which is essential for an efficient flow of the pollutant solution during the photocatalytic tests. The composite microspheres were tested as photocatalyst for the decomposition of methyl orange and paracetamol. In addition to photocatalytic activity under continuous flow conditions, the microspheres offer the advantage that they can easily be removed from the reaction medium, which is an appealing aspect for industrial applications.

Ana C. Marques, Mário Vale, Daniel Vicente, Murielle Schreck, Elena Tervoort, Markus Niederberger, “Porous Silica Microspheres with Immobilized Titania Nanoparticles for In-Flow Solar-Driven Purification of Wastewater”, Global Challenges, 5 (5) (2021) 2000116, DOI: https://doi.org/10.1002/gch2.202000116