- Thesis topic: The Application of Lanthanum Doped Titanium Dioxide Photocatalyst on Environmental Pollutant Degradation

- Doi: https://doi.org/10.6840/cycu201900018

- Abstract: 

     In this study, Lanthanum (La)-doped with TiO2 photocatalyst was synthesized by utilizing recycled La from the waste fluorescent powder. Subsequently, the feasibility and benefits of various pollutants degradation, coating of various carriers and photocatalytic kinetics under solid-gas phase and solid-liquid phase was investigated by photocatalytic dynamic analysis.
       First, the rare earth metal in waste fluorescent powder was leached by acid agents and then La-doped TiO2 and coated on the PVDF film which was modified by low-temperature plasma. The photocatalytic activities and benefits of dye degradation were discussed. It was found that the best result is 1wt% La additive under the blue light (450-495 nm) irradiation and the result indicates that it could be repeated up to 11 times. Although the efficiency of photocatalytic dye degradation slightly decreased after coating the La/TiO2 on the film, however, the kinetic, hydrophilicity and permeability of reaction could be greatly improved.
       The utilization of La-doped TiO2 and fiberglass cloth coating are used on simulating the photocatalytic degradation of toluene from the exhaust gas by SVE method applying on groundwater contamination site. The results interpret that 1 wt% La doping into TiO2 on glass is 22.8% of toluene degradation by humidity of 60%. The toluene degradation could reach up to 94.84% for three fiberglass cloth coated with La-TiO2 under UV light. The toluene degradation could still reach up to 54.32% under visible light irradiation. The recommended module design is under 60% of relative humidity and 1 wt% La-TiO2 coated on fiberglass cloth. The one piece of cloth is the best cost-effectiveness choice.
        This study was also based on the circular economy. The lanthanum in waste fluorescent powder was extracted then doped with TiO2, and the La-TiO2 complex was coated on the ceramic filter by immersion method. The acetone degradation was 36.9% under 0.5wt% La/TiO2 coated on ceramic filter, while it is 23.5 % for the commercial TiO2. The best efficiency of NO degradation is 77.2% and NO2 generation was only 8ppb which is better than commercial TiO2. Accordingly, the degradation efficiency of acetone and NO for La-TiO2 coated ceramic filter is better than commercial TiO2.
          The results of experiments and reaction rate constants indicated that the photocatalytic reaction of La/TiO2- assisted under visible light irradiation was greatly increased than commercial TiO2. The optimal degradation reaction for gas phase pollutants (NO, toluene, acetone) is NO with the shortest reaction time.

Keywords: photocatalytic reaction, La doped TiO2, hydrophilicity, La-TiO2/PVDF membrane, acetone, NO