Preparation of adsorptive TiO2/SiO2 core-shell nanospheres by ultrasonic-coupled alkali leaching process: Synergy of adsorption and photocatalysis towards 2,4-dinitrophenol removal

Spent selective catalytic reduction (SCR) catalysts comprise of abundant valuable TiO2. Therefore, recovery of TiO2 from spent SCR catalysts has highly economic benefits. In this study, an ultrasonic-coupled alkali leaching process was developed for environment-friendly preparation of adsorptive TiO2/SiO2 core-shell nanospheres from spent SCR catalysts. The results show that the synergy of ultrasonic and alkali leaching significantly enhances the separation of other ingredients from TiO2/SiO2, and the addition of NaOH, when compared with the traditional roasting-leaching process, decreases by 70%. The as-prepared adsorptive TiO2/SiO2 core-shell nanospheres exhibit superior adsorptive and photocatalytic performance for 2,4-dinitrophenol removal, and 99.9% of degradation rate was achieved within 120 min under the cooperation between adsorption and photocatalytic oxidation. This study provides a potential method for recycling of valuable adsorptive TiO2/SiO2 core-shell nanospheres from spent SCR catalysts.