Alveolar TiO2-β-SiC photocatalytic composite foams with tunable properties for water treatment

Abstract New alveolar TiO 2 -β-SiC photocatalytic composite foams gathering within a ready-to-use media, the TiO 2 active phase and the β-SiC alveolar foam structure have been prepared through a Shape Memory Synthesis (SMS) replica method. They have been obtained by incorporating TiO 2 powders inside the infiltration slurry used for transforming the pre-shaped polyurethane foam into its corresponding carbide. The photocatalytic composite foams contained 16 wt. % and 24 wt. % of TiO 2 , most of them being available for the reaction by being located in the external layer of the foam rather than dispersed within the foam matrix, so that no further post-synthesis immobilization process was needed for coating the foam with TiO 2 active phase. The adsorption behaviour of the TiO 2 -β-SiC composite foams towards the Diuron pollutant in water was tuned by applying a final calcination treatment to the as-synthesized foams within the 400–700 °C range, that allowed to tune the amount of residual unreacted carbon within the foams, while allowing the formation of small TiO 2 crystallites via the selective oxidation of TiC carbide, and thanks to the β-SiC resistance to oxidation. The TiO 2 -β-SiC composite foams calcined at 700 °C outperformed a reference β-SiC supported foam TiO 2 catalyst in terms of diuron degradation, while the reference foam remained more efficient in terms of mineralization rate.