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.