Mn-Fe氧体/SiO_2/TiO_2磁载光催化剂的制备及性能

Synthesis and Characterization of Manganese Ferrite/Silica/Titania Nanometer Magnetic Photocatalytic Compound

以化学共沉淀法制备Mn-Fe氧体,正硅酸乙酯为前躯体对其进行多次包覆SiO2,得到致密SiO2保护层的Mn-Fe氧体软磁性载体。采用溶胶-凝胶法在软磁性载体上负载TiO2光催化剂,得到Mn-Fe氧体/SiO2/TiO2纳米磁载性复合光催化剂。用X射线衍射仪(XRD)、振动样品磁强计(VSM)进行了表征;以甲醛为模拟污染物,评价了其光催化活性;以磁性回收装置测定了其回收率。结果表明,对TiO2进行晶化热处理时,磁载体中金属离子在TiO2有所渗透,且随着TiO2负载次数的增多,金属离子在TiO2中的含量逐渐降低,TiO2粒径逐渐增大;复合催化剂的比饱和磁化强度减小,矫顽力增大,其磁回收效率逐渐降低,光催化活性逐渐增强。当TiO2负载次数为10次时,该磁载催化剂的催化活性是纯TiO2的1.053倍,回收率为70.52%。该光催化剂既具有较高的光催化活性又具有高的回收性能。

Mn-ferrite powders have been prepared successfully by coprecipitation method, the products covered by a uniform silica shell using terraethoxysilane. The magnetic composie carrier- manganese-ferrite/silica were prepared, titania nanoparticles were directly coated on the silica coated manganese ferrite forming photoactive titania shell by sol-gel method. The prepared composite powders were characterized with ray diffraction （XRD）, vibrate sample agnetometer （VSM）. The photocatalytic activity of composite particles were tested by formaldehyde, magnetic separation efficient estimated by recovery system. The result shows, with heat-treatment, the iron of magnetic carrier can dipped into titania contracture. When titian layer became thick, the iron dipped rate of iron in titania diminished. The coercive force and photoactivity of the composite particles decreased when titania photo catalysis layer become thicker. But the specific saturation and recovery efficient became lower. When titania was covered 10 times, the photocativity of composite particles as 1.053 times as fresh titania, and the recycled rate was 70.52%. The composite particles have higher activity and recycled efficient.