• 关键词：Fe₃O₄  PEI改性  Fe₃O₄/PEI  磷  吸附效率  吸附机制

• 基金项目：农业部公益性行业（农业）科研专项（No.20150306）；江苏省农业自主创新资金项目（No.CX（15）5004）

• 胡小莲
• 1. 南京理工大学化工学院, 南京 210094;2. 江苏省农业科学院农业资源与环境研究所, 农业部长江下游平原农业环境重点实验室, 南京 210014

• 唐婉莹
• 南京理工大学化工学院, 南京 210094

• 何世颖
• 江苏省农业科学院农业资源与环境研究所, 农业部长江下游平原农业环境重点实验室, 南京 210014

• 杨林章
• 江苏省农业科学院农业资源与环境研究所, 农业部长江下游平原农业环境重点实验室, 南京 210014

• 张婉
• 南京理工大学化工学院, 南京 210094

• 修瑞瑞
• 江苏省农业科学院农业资源与环境研究所, 农业部长江下游平原农业环境重点实验室, 南京 210014

• 摘要：采用化学共沉淀法，以聚乙烯亚胺（PEI）为改性剂，制备了聚乙烯亚胺改性的纳米四氧化三铁复合材料（Fe₃O₄/PEI）.Zeta电位、透射电镜和FTIR表征结果显示，PEI修饰提高了纳米Fe₃O₄在水中的分散性和稳定性，同时也增强了其表面正电荷，从而提高了Fe₃O₄对水中磷酸根的去除能力.在磷酸根初始浓度为50 mg·L^-1，Fe₃O₄/PEI投加量为200 mg，pH=3，温度为25 ℃的条件下，Fe₃O₄/PEI对100 mL磷酸根的吸附去除率达到91%.吸附过程在3 h内达到平衡.吸附等温数据表明，该吸附过程符合Langmuir吸附等温方程，可决系数R²达到0.99，最大吸附量为29.88 mg·L^-1.Fe₃O₄/PEI复合材料重复利用性好，在第5次吸附-解析后还能保持对磷酸根75%以上的吸附去除率.磷的解析效率随着pH增加而增加，在pH=13时，解析效率达到65%.

• Abstract：In this study, magnetite (Fe₃O₄) modified with polyethyleneimine (PEI) was synthesized by chemical coprecipitation method. This magnetic composite (Fe₃O₄/PEI) was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and Zeta potential. Furthermore, the adsorption-desorption process and mechanisms of Fe₃O₄/PEI towards phosphate were investigated in aqueous solutions. Results indicated that adsorption efficiency of phosphate by Fe₃O₄/PEI reached 91%, which was higher than that of Fe₃O₄,under the condition of 50 mg·L^-1 of initial phosphate concentration, 200 mg Fe₃O₄/PEI, and pH 3 at room temperature, the desorption efficiency reached 65% at pH 13. Polyethyleneimine not only improved the dispersibility of Fe₃O₄, but also increased the positive charge on the surface of Fe₃O₄. The phosphate adsorption behavior by Fe₃O₄/PEI was in good agreement with the Langmuir adsorption model. Adsorption kinetic study showed that the equilibrium was reached in 3 hours, and the adsorption process is well fit by pseudo-second-order kinetic model. Phosphate was adsorbed to the Fe₃O₄/PEI surface via electrostatic attraction and ligand exchange. In conclusion, our investigation indicates that Fe₃O₄/PEI is a type of stable and highly efficient material for adsorption of phosphate.

• Key words：Fe₃O₄ nanoparticle  polyethyleneimine modification  Fe₃O₄/PEI nano-composites  phosphate removal  adsorption mechanisms

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