以FeCl2·4H2O和FeCl3·6H2O为原料,采用化学共沉淀法制备了Fe3O4磁性纳米粒子;然后采用Stber法,利用正硅酸乙酯的水解和缩聚反应成功制备出Fe3O4@SiO2复合粒子;最后利用氨基与羧基的缩聚反应在颗粒表面结合上螯合剂乙二胺四乙酸二钠(EDTA),成功制备出Fe3O4@SiO2@EDTA磁性复合微球。利用红外光谱、热重、纳米粒度仪、扫描电镜和透射电镜等手段对复合微球进行表征,并研究了磁性复合微球对Cr6+、Mn7+重金属离子的吸附效果。结果表明:Fe3O4@SiO2@EDTA磁性复合微球对Mn7+的平衡吸附量达到11.85mg/g左右,对Cr6+的平衡吸附量达到8.0mg/g左右。可以有效地去除水溶液中的重金属离子,而且可以磁分离。同时吸附动力学模型符合准二级动力学模型;吸附等温模型符合Langmuir吸附模型。
Fe3O4 magnetic nanoparticles were prepared by chemical coprecipitation method using FeCl2·4H2O and FeCl3·6H2O as raw materials.Fe3O4@SiO2 composite particles were successfully prepared by hydrolysis and polycondensation of tetraethyl orthosilicat using Stöber method.Finally,the chelating agent EDTA was bonded to the surface of the particles by the polycondensation reaction of amino group and carboxyl group.Fe3O4@SiO2@EDTA magnetic composite microspheres were characterized by IR,TG,LPSA and SEM.The adsorption properties of the microspheres were studied.The results shown that the equilibrium adsorption capacity of Fe3O4@SiO2@EDTA to Mn7+ reached 11.85mg/g.The equilibrium adsorption amount to Cr6+ reached 8.0mg/g.The heavy metal ions in the aqueous solution can be effectively removed,and can be separated magnetically.At the same time,the adsorption kinetic model showed that it accorded with the quasi-secondary kinetic model,and the adsorption isotherm model accorded with the Langmuir adsorption model.
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