Construction of CeO2/TiO2 heterojunctions immobilized on activated carbon fiber and its synergetic effect between adsorption and photodegradation for toluene removal

Toluene, as one of the most representative volatile organic compounds (VOCs), poses a serious threat to the atmospheric environment and human health. Herein, cerium dioxide (CeO2)/TiO2 immobilized on activated carbon fiber (ACF) is fabricated by ultrasonic-assisted sol-gel impregnation method for toluene removal. Characterizations of CeO2/TiO2/ACF composites reveal that CeO2 disperses or covers the surface of TiO2/ACF, and Ce4+ does not enter the lattice of TiO2 to replace Ti4+. The TEM and UV-vis analysis indicate the formation of heterojunction between TiO2 and CeO2. The Ce4+/Ce3+ redox centers significantly boost the separation efficiency of electron-hole pairs. The maximum removal efficiency of 1.5% CeO2/TiO2/ACF can reach up to 90%, much higher than 54% over TiO2/ACF. The CeO2/TiO2/ACF composites exhibit high removal efficiency of toluene due to the synergetic effects between adsorption and photodegradation. The gas-phase photodegradations are benzene, benzaldehyde, hexane, phenol, O-xylene, and phenylethyl acetate. CeO2/TiO2 heterojunctions immobilized on ACF achieve the perfect combination of adsorption and photocatalysis, and greatly improve the removal efficiency of dynamic toluene.