纳米CeO2粒子光催化降解亚甲基蓝的研究

摘要

CeO2 nanoparticles were prepared by a simple precipitation method and calcinated at 600 ℃. CeO2 nanoparticles were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy (FT- IR), X- ray diffraction (XRD), N2 adsorption- desorption, scanning electron microscopy (SEM). The photodeg⁃radation of methylene blue catalyzed by CeO2 nanoparticles was studied under UV and sunlight irradiation. The optimum reaction conditions of photodegradation were that the initial concentration of methylene blue was 5.0 mg/L, the initial pH=11, the dosage of CeO2 nanoparticles catalyst calcinated at 600℃was 1.0 g/L. The remov⁃al rate of methylene blue was 87.05% within 60 min under UV irradiation of 300 W. The results indicated that the photodegradation of methylene blue catalyzed by CeO2 fol owed a pseudo first order kinetics. The photoca⁃talysis reactions fit the heterogeneous catalytic kinetic equation Langmuir- Hinshelwood kinetic model. In this case the rate constant for the surface reaction k was 0.138 5 mg/(L·min) and the adsorption equilibrium con⁃stant Kdye was 0.399 7 L/mg.%采用共沉淀法并在600℃焙烧制备纳米CeO2光催化剂，利用热重分析、傅立叶变换红外光谱（FT-IR）、X射线衍射（XRD）、N2吸附-脱附、扫描电子显微镜（SEM）等方法对纳米CeO2粒子进行了表征，并研究了纳米CeO2粒子催化剂对亚甲基蓝溶液的光催化降解行为。结果表明，在300 W汞灯照射下，对于初始质量浓度为5.0 mg/L和初始pH=11的亚甲基蓝溶液，加入600℃煅烧的纳米CeO21.0 g/L，反应60 min，亚甲基蓝降解率可达87.05%。该光催化降解反应表现为一级动力学反应，反应速率服从多相催化动力学方程Langmuir-Hinshelwood方程，光催化剂表面反应速率常数k为0.1385 mg/（L·min），吸附平衡常数Kdye为0.3997 L/mg。