Photocatalytic degradation of vehicle exhaust using Fe-doped TiO2 loaded on activated carbon

Abstract

To enhance the photocatalytic degradation efficiency of TiO2 on vehicle exhaust (VE), nanoscale Fe-doped TiO2 (Fe-TiO2) was synthesized and loaded on the activated carbon (AC) to prepare a composite photocatalyst AC/Fe-TiO2. The loaded amount of Fe-TiO2, the chemical compositions, adsorption-desorption properties, and photocatalytic degradation efficiency of the AC/Fe-TiO2 on VE were discussed. Results indicated that the synthesized Fe-TiO2 only contained anatase phase, and the optical absorption edges of Fe-TiO2 showed an obvious red shift. Fe-TiO2 particles were successfully loaded on the AC. Fe-TiO2 particles were mainly distributed in the macropores and mesopores of the AC. The loaded Fe-TiO2 had a slight effect on the AC adsorption property. Furthermore, the Ti concentration on the AC was increased, but the specific surface area, total pore volume, and average pore size of the AC were decreased with the increase in loading rounds of Fe-TiO2. The AC with the narrow pores demonstrated the best adsorption, belonging to narrow pore adsorption. Additionally, each component of VE was enriched on Fe-TiO2 surface. This enhanced effectively the degradation efficiency on VE due to the photocatalytic activity of Fe-TiO2 and the oxidation-reduction of active functional groups on the AC surface. The photocatalytic degradation efficiency of AC/Fe-TiO2 was increased due to the synergistic effect between AC adsorption and Fe-TiO2 photocatalysis. This facilitated the photocatalytic degradation reaction of Fe-TiO2 with VE. Finally, excessively loaded Fe-TiO2 lowered the specific surface area, total pore volume, and average pore size of the AC, leading to a decrease in adsorption performance of AC and photocatalytic degradation efficiency of Fe-TiO2. Three loading rounds were proposed to prepare AC/Fe-TiO2 for purifying VE in road tunnels.