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

Abstract

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.