中文摘要：

采用柠檬酸盐前驱体技术，合成了粒径约为20～70nm的尖晶石结构MnFe2O4纳米颗粒，用聚乙烯亚胺（PEI）对MnFe2O4纳米颗粒进行表面处理后，以异丙醇钛为前驱物，采用sol—gel法在纳米MnFe2O4表面包覆锐钛矿型TiO2纳米层形成核壳结构。利用透射电子显微镜（TEM）、X射线衍射仪（XRD）和振动样品磁强计等测试手段对样品的结构、形貌、粒径以及磁学性能等进行了表征。采用罗丹明B的光催化降解反应对所制催化剂的活性进行了评价。结果表明，核壳结构TiO2／MnFe2O4复合纳米颗粒的光催化活性随着壳层厚度的增加而增强，当达到一定厚度以后，其催化活性不随壳层厚度的增加而改变。复合颗粒中TiO2含量达到30wt％，反应时间4h时，TiO2／MnFe2O4磁性光催化剂对罗丹明B的光降解率达到100％，与纯TiO2纳米粉体的催化活性相当，且光催化活性稳定，是一种便于回收、可重复使用的高效光催化剂。

英文摘要：

The anatase TiO2/MnFe2O4 composite nanoparticles with a core-shell structure have been obtained. The core MnFe2O4 nanoparticles were synthesized by the co-precipitation method, and the shell TiOz nanocrystals were derived using the sol-gel technology followed by a heat-treatment at 450℃. The TiO2/MnFe2O4 samples were characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The TiO2/MnFe2O4 composite particles can be used as a magnetic photocatalyst, which can be fluidized and recovered by an applied magnetic field enhancing both the separation and mixing efficiency for recyclable fluids. When the mass fraction of TiOz is 30 % and there is enough UV illumination （4 h in our experiments）, the photodegradation ratio of Rhodamine B by the composite of TiO2/MnFe2O4is 100%, similar to that of the pure TiO2.