用于水基磁流体制备的环境友好分散剂的选择

The Selection of Environment-Friendly Dispersant in the Preparation of Water-Based Magnetic Fluid

用共沉淀法在室温条件下制备纳米Fe3O4磁性粒子，选用聚乙二醇、明胶、琼脂等环境友好分散剂制备水基磁流体。最佳工艺条件为：（1）Fe^3＋／Fe^2＋（物质的量）之比在1．70～1．75；（2）沉淀剂25％NH3·H2O过量（20-30）％，在温度35℃，pH值10-11，搅拌速度3000r／main，反应时间为1h；（3）琼脂、明胶的最佳用量为（0．050～0．060）g／150mL；包覆的最佳温度为（55～60）℃，pH值为9～11；聚乙二醇作为第二次包裹时，最佳温度为55℃，搅拌速度3000r／min，反应时间是1h；并用透射电镜、分光光度计、古埃磁天平等进行了初步表征。在Fe3O4粒子中加入镝（n（Fe）：n（Dy^3＋）=14：1），明显提高了磁性。

Fe3O4 magnetic nanoscale water- based magnetic fluid was prepared by co -precipitation in the room temperature with polyethylene glycol, gelatin and agar as the environment - friendly dispersant. The optimum conditions are as follows： 1） Fe^3＋/Fe^2＋ （mole ratio） is 1.70 - 1.75; 2） the precipitant, 25% ammonia water was used （20 -30% ） excessively under 35%, pH of 10- 11 and with a stirrer speed of 3 000 rpm for 1 h ; 3 ） in the first package process with gelatin and agar, the optimum amounts is 0. 050 - 0. 060g/150mL at the temperature of （55 -60） % and pH of 9 - 11 ; in the first package process with polyethylene glycol, the optimum temperature is at 55 ℃ and with a stirrer speed of 3 000 rpm for 1 h. Water - based magnetic fluid is characterized by transmission electron microscopy, infrared spectrum, spectrophotometry and gouy magnetic balance. The result shows that the introduction of dysprosium into magnetic fluid will increase significantly the magnetism.