Novel synthesis of nano-cerium oxide using ultrasonic microreactor: Process optimization and AO7 degradation

Abstract

Nano-CeO2 has been widely used in catalysis, polishing, coating, biomedicine, and other fields, but controlling particle size and homogeneity using conventional reaction techniques remains a great challenge. In this study, a 20 kHz ultrasonic microreactor (USMR) was applied to enhance precursor mixing, reduce agglomeration, and achieve small nanoparticles with a narrow size distribution. The effects of ultrasonic power, residence time, NH3·H2O concentration, and calcination temperature were investigated in detail. Under optimal conditions, the particle size, Ce3+ concentration and specific surface area of nano-CeO2 obtained using the USMR are averaged to be 6 nm, 25.0 % and 114 m2/g, respectively, which is superior to 32 nm, 22.4 % and 60 m2/g using the traditional precipitation method, as well as 9 nm 24.3 % and 101 m2/g using microreactor. Due to the outstanding feature, the CeO2-USMR showed much better catalytic activity in the oxidative degradation of acid orange 7. This study highlights a new strategy for preparing nano-CeO2, which may provide the USMR technique for the synthesis of small metal oxides and ceramic-based nanocomposites for catalysis and biomedical applications.