Fast sintering of titania monoliths for photocatalytic degradation of organic micropollutants

Scalable solutions to efficiently remove organic micropollutants from water are urgently needed to address the significant adverse health effects their accumulation causes on the environment and in humans. Solutions based on slurries of titania (TiO2) nanoparticles, while effective in the lab, cannot be scaled up due to cost and environmental concerns. Conversely, titania monolithic structures are not photoactive as high sintering temperatures result in the predominance of the non-photoactive rutile phase. In this work the combination of 3D printing and fast sintering allowed, for the first time, to obtain titania monoliths which are mechanically stable and retain their photoactivity. The latter arises from the anatase-rich composition of the monoliths, a result not possible using convectional sintering methods. To demonstrate their photoactivity, the porous monoliths were used in a recirculating flow reactor to degrade primidone, a widely used drug and ubiquitous micropollutant. Results for the best performing monolith showed a quantum yield value of 1.1 × 10−5and an electrical energy per order value of 13 kWh m−3, both significantly outperforming literature data. These results show a clear route to scaling-up the fabrication of photocatalytically active titania monoliths capable of effectively degrading organic micropollutants in water, whose presence is a major health and environmental hazard.