TiO2 3D structures for environmental purposes by additive manufacturing: Photoactivity test and reuse

Abstract From a technical point of view, currently, one of the most important problems to be solved in solar heterogeneous photocatalytic processes is related to the impractical use of the photocatalytic material in suspension form. In this study, we propose and develop 3D-printed hierarchical structures of entirely TiO 2 consistency in order to investigate their effective photochemical and structural performance. Robocasting and deposition processes assisted the extrusion process through a syringe-type nozzle, dispensing, layer-by-layer, fine filaments of the catalytic paste and manufactured solid square-lattice double-diagonal (SLDD) structures. The concentration effect of SLDD solid pieces and nanopowder suspensions of TiO 2 were compared for acesulfame (ACE) degradation as a model pollutant. 99% and 79% removal of 20 mg/L of ACE in solution were reached in 60 min of UV–Vis irradiation by use of 0.500 and 22 g/L of TiO 2 in slurry and SLDD form, respectively. Long-term periods of use of SLDD pieces showed that the photocatalytic activity, pH and DO evolution remain unaltered after several cycles of reuse without macrostructure deformation or deterioration of the SLDD pieces. The optimal geometry of 3D printed structures of entirely TiO 2 composition with optimum photonic flow distribution in solar reactors is a promising assignment to be achieved for the incoming commercial use of photocatalytic technologies at large scale for environmental sustainable applications.