Study On The Influence Of Upconversion Fluorescence Material Er³⁺:YAlO₃ On Sonocatalytic Activity Of TiO₂ And Its Composites

Recently, Advanced Oxidation Process (AOPs) has obtained more and more widespread attention in environmental treatment. Among them, photocatalysis, ozonization, peroxide oxidation and Fenton reagent are widely favored in effluent treatment. But they exhibit powerless in treating wastewater with high concentration in the large scale due to their limitation in actual applications. However, the sonocatalytic degradation is the most effective way to decompose the dyes in non- or low-transparent effluents in the large scale. The sonolysis is mainly attributed to the cavitation effect and pyrolysis and its efficiency is very low. Therefore, how to enhance degradation efficiency of sonocatalytic degradation is a topic of concern to researchers today.In recent years, the application of sonolysis coupled with catalyst, namely has been widely studied, especially photocatalyst. TiO₂ as a photocatalyst was widely used in the effluent treatment due to its high efficiency, stability, non-toxic, low cost and high catalytic efficiency. The combination of sonolysis and TiO₂ provides additional nuclei for bubble formation, enhances mass transfer of organic pollutants between the liquid phase and uses of ultrasound-induced light, thus the degradation efficiency of sonocatalytic degradation enhance obviously. However, its band gap results in the fast recombination rate of photogenerated electron-hole pairs and the low efficient absorption of ultrasound-induced light. Thus, in this paper Er³⁺:YAlO₃ as up-conversion luminescence agent and combination of semiconductors were used in the sonocatalytic degradation in order to fully use of sonoluminescence and separate the photogenerated electron-hole pairs for enhancing the degradation efficiency.In this paper, Er³⁺:YAlO₃/TiO₂, Er³⁺:YAlO₃/TiO₂-ZnO, Er³⁺:YAlO₃/TiO₂-Fe₂O₃ and Er³⁺:YAlO₃/TiO₂-SnO₂ composites were successfully prepared. Then, the prepared sonocatalysts were characterized through XRD and SEM. Acid red B was as the model pollutant to exam their catalytic activity under the ultrasonic irradiation, and its kinetics of degradation reaction in the presence of these composites were investigated. UV-Vis spectra and ion chromatography were used to monitor the process of organic dye pollutants. Furthermore, the study on the influence of the amount of Er³⁺:YAlO₃, heat-treatment temperature and heat-treatment time on the catalytic activity of Er³⁺:YAlO₃/TiO₂ composites were conducted. Besides, influences of amount of sonocatalyst and radical scavenger on the acid red B degaradation were studied as well as its ability to degrade other dyes. And for the Er³⁺:YAlO₃/TiO₂-M_xO_y (M_xO_y = ZnO, Fe₂O₃ and SnO₂) composites, Ti:M (M = Zn, Fe and Sn) mole rate, heat-treatment temperature and heat-treatment time on the catalytic activity of these composites were conducted as well as their ability to degrade other dyes. Finally, the upconversion luminescence process of Er³⁺:YAlO₃ and the excitation principle of Er³⁺:YAlO₃/TiO₂-M_xO_y under ultrasonic irradiation was proposed. The results showed that Er³⁺:YAlO₃ and combination of semiconductors successfully use of use of sonoluminescence and separate the photogenerated electron-hole pairs for further enhancing the degradation efficiency of organic pluttant in industrial effluent.