Application of recycled lanthanum-doped TiO2 immobilized on commercial air filter for visible-light photocatalytic degradation of acetone and NO

Herein, La-doped TiO2 photocatalyst was synthesized by utilizing the recycled lanthanum from the waste fluorescent powder, and then was firstly immobilized on a commercial ceramic filter with porous structure and high surface area. Immobilized La-doped TiO2 (La-TiO2) was applied for photocatalytic degradation of acetone and NO at the ppb level under visible light region. It was found that 0.5 wt% La doping into TiO2 exhibited an excellent photocatalytic performance. The photocatalytic removal efficiency of acetone and NO under visible light could reach up to 38% and 98% respectively, which were much higher than that of pure TiO2 (28% and 65%, respectively). Moreover, the results of various physicochemical characterization showed that La-TiO2 sol-gel could be uniformly immobilized on the ceramic filter by impregnation method and followed by a low-temperature calcination treatment process. The three-dimensional porous structure of ceramic air filter resulted in more adsorption sites and reaction contact between pollution gas and photocatalyst surface, which is superior to the powdered TiO2 catalyst on substrates or thin film deposited on glasses. In order to the further application, the effect of relative humidity on photocatalytic performance was discussed. This work will provide a new perspective for promoting large-scale environmental application of immobilized photocatalysts.