C,N-doped TiO2 monoliths with hierarchical macro-/mesoporosity for water treatment under visible light

Paolo Boscaro (1) , Thomas Cacciaguerra (1) , Didier Cot (2) , François Fajula (1) , Vasile Null Hulea (1) , Anne Galarneau (1)

1 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 IEM - Institut Européen des membranes

C,Nsingle bondTiO2 monoliths with homogeneous interconnected macro-/mesoporous hierarchical porosity, consisting in 83% anatase phase, exhibiting high visible light absorption were prepared in one pot synthesis. The hierarchical porosity was controlled by coupling a sol-gel method with a spinodal decomposition and the improved visible light absorption was obtained by self C,N-grafting during thermal treatment. Titanium isopropoxide, N-methylformamide, poly(ethylene oxide), and hydrochloric acid were used as reagents to form a sol, which was then treated at 40 and 60 °C, followed by a solvothermal treatment in autoclave at 200 °C in isopropanol. The monoliths were further heated at different temperatures from 250 to 500 °C under air. The best compromise between the structural and textural properties (TiO2 phase, surface, volume, pore diameter), the visible light absorbance and the mechanical properties was obtained for a calcination at 350 °C for 5 h. In batch mode, in glass containers, the monoliths demonstrated remarkable efficiency as photocatalysts under natural sunlight and artificial visible light with the total discoloration of the azo dye Orange G aqueous solution in 1 h compared to benchmark TiO2 P25 nanoparticles, which proved inefficient under these conditions. More interestingly, the monoliths used as reactors in flow mode in a recirculating system proved very efficient for the total discoloration of Orange G dye solution revealing the high potential of these TiO2 monoliths for continuous flow wastewater treatment under visible light.

Mots clés: TiO2 monolith; Visible light; Photocatalysis; Dyes degradation; Flow process; Wastewater treatment

Domaines: Catalyse; Autre; Ingénierie de l'environnement

Paolo Boscaro, Thomas Cacciaguerra, Didier Cot, François Fajula, Vasile Null Hulea, et al.. C,N-doped TiO2 monoliths with hierarchical macro-/mesoporosity for water treatment under visible light. Microporous and Mesoporous Materials, 2019, 280, pp.37-45. ⟨10.1016/j.micromeso.2019.01.036⟩. ⟨hal-02001891⟩