Preparation of pumice-loaded CeO2/Bi2WO6 photocatalysts and treatment of tetracycline wastewater with a continuous flow photocatalytic reactor

Pumice-loaded CeO2/Bi2WO6 photocatalysts were prepared with a typical solvothermal method by using pumice as the macroporous carrier. The photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and element mapping. The preparation conditions were optimized and the photoactivity was evaluated via photocatalytic tetracycline degradation under visible light radiation. Moreover, the photocatalysts were applied to a continuous flow reactor and the optimal conditions were studied. It was found the CeO2/Bi2WO6 catalysts were successfully loaded on the surfaces and pores of pumice. The optimal catalyst/pumice loading ratio was 1:4 mmol/g, and the average load rate of the photocatalysts was 37.24%. Under visible-light irradiation, the pumice-loaded CeO2/Bi2WO6 catalysts could well photocatalytically degrade tetracycline, with a degradation rate within 90 min up to 91.72%, and were stable photocatalytically. Experiments with the continuous flow reactor showed the optimal catalyst quantity, light source intensity, pollutant concentration and hydraulic retention time were 10 g/L, 140,000 lx, 50 mg/L and 6 h, respectively, when the tetracycline degradation rate was stably improved to 90.00%.