title: MnO2/CeO2 for catalytic ultrasonic decolorization of methyl orange: Process parameters and mechanisms.
abstract: MnO2/CeO2 catalyst was prepared and characterized by means of Brunauer-Emmet-Teller (BET) method, X-ray diffraction (XRD) and scanning electron microscope (SEM). The characterization showed that MnO2/CeO2 had big specific surface area and MnO2 was dispersed homogeneously on the surface of CeO2. Excellent degradation efficiency of methyl orange was achieved by MnO2/CeO2 catalytic ultrasonic process. Operating parameters were studied and optimized. The optimal conditions were 10 min of ultrasonic irradiation, 1.0 g/L of catalyst dose, 2.6 of pH value and 1.3 W/ml of ultrasonic density. Under the optimal conditions, nearly 90% of methyl orange was removed. The mechanism of methyl orange degradation was further studied. The decolorization mechanism in the ultrasound-MnO2/CeO2 system was quite different with that in the ultrasound-MnO2 system. Effects of manganese and cerium in catalytic ultrasonic process were clarified. Manganese ions in solution contributed to generating hydroxyl free radical. MnO2/CeO2 catalyst strengthened the oxidation ability of ultrasound and realized complete decolorization of methyl orange.
authors.affiliation: School of Environment & Natural Resource, Renmin University of China, 59 Zhongguancun Street, Beijing 100872, China.
authors.forename: He
authors.initials: H
authors.lastname: Zhao
authors.affiliation: School of Environment & Natural Resource, Renmin University of China, 59 Zhongguancun Street, Beijing 100872, China. Electronic address: zgm@ruc.edu.cn.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhang
authors.affiliation: School of Environment & Natural Resource, Renmin University of China, 59 Zhongguancun Street, Beijing 100872, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Chong
authors.affiliation: School of Environment & Natural Resource, Renmin University of China, 59 Zhongguancun Street, Beijing 100872, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhang
authors.affiliation: School of Environment & Natural Resource, Renmin University of China, 59 Zhongguancun Street, Beijing 100872, China.
authors.forename: Yucai
authors.initials: Y
authors.lastname: Liu
keywords: Catalytic ultrasonic process; Hydroxyl free radical; Manganese ion; Methyl orange; MnO(2)/CeO(2)