水基Fe_3O_4磁流体的制备

Preparation of Water-based Fe_3O_4 Magnetic Fluid

以聚乙二醇(PEG4000)为表面活性剂,通过化学共沉淀法制备水基Fe3O4磁流体,探讨了pH值、Fe3+与Fe2+摩尔比、温度、聚乙二醇质量浓度对磁流体形成和稳定性的影响。结果表明,在pH值为12～13、Fe3+与Fe2+摩尔比为1.75∶1～2∶1之间、温度为60℃、聚乙二醇质量浓度为50g/L的条件下,能制备得到磁性强和稳定好的水基Fe3O4磁流体。利用TEM、IR和古埃磁天平对Fe3O4磁流体观察和测量表明,Fe3O4纳米粒子的平均粒径为(20±5)nm,粒子基本呈方形;在无外部磁场存在下,48h内磁流体无明显沉降趋势;磁流体的磁化率较大,并且随着磁场强度的增大而增大,Fe3O4纳米粒子是一种强顺磁性材料。

Water-based Fe_ 3O_ 4 magnetic fluid was prepared by chemical co-precipitation in the presence of a surfactant PEG-4000. The effects of preparation conditions such as pH value, n(Fe 3+)/n(Fe 2+), temperature and PEG mass concentration on the formation and the stability of the magnetic fluid were investigated. The results show that under the conditions of pH value between 12 and 13, n(Fe 3+)∶n(Fe 2+)=1.75∶1~ 2∶1, PEG mass concentration of 50 g/L and temperature 60 ℃, the water-based magnetic fluid was obtained with strong magnetism and good stability. The TEM image shows that the particles of the magnetic fluid were square with an average size of about (20±5) nm. The magnetic fluid did not show obvious sedimentation trend in 48 hours without external magnetic field. The magnetic susceptibility of the magnetic fluid powder was measured by means of a magnetic balance, and the results show that the magnetic susceptibility was high, and increased with the increase of the magnetic field strength, which shows that the Fe_ 3O_ 4 nanoparticles were paramagnetic.