Abstract:

Nano-Fe₃O₄ particles are first synthesized under ultrasonic condition, and the ultrasonic enhanced functionalized nanocomposites Fe₃O₄-mPD/SP(50∶50) modified with amino, imino and sulfonic acid are synthesized in one step in presence of ultrasonic irradiation, which were characterized by TEM, XRD, IR, TGA, VSM and BET. The adsorption properties of Cr(Ⅵ) were investigated, which show that the pH value of the solution has a significant effect on the adsorption of Cr(Ⅵ) by Fe₃O₄-mPD/SP(50∶50), and the adsorption is best when pH=2. The amount of adsorbent, competitive anion(Cl^-,NO₃^-,SO₄^2-) and temperature all had effect on the adsorption of Cr(Ⅵ). The adsorption mechanism of Cr(Ⅵ) by Fe₃O₄-mPD/SP(50∶50) was discussed, which show that the quasi-second order kinetic equation can describe the adsorption behavior of Cr(Ⅵ) on Fe₃O₄-mPD/SP(50∶50) well, k₂=1.324×10^-3 g·mg^-1·min^-1, q_e=77.157 mg·g^-1; The isothermal adsorption data were in accordance with the Freundlich model, K_F=34.464 mg^1-(1/n) ·L^1/n·g^-1, n=3.861. The adsorption of Cr(Ⅵ) is a spontaneous process, ?G⁰<0，?S⁰=73.368 J·mol^-1·K^-1, ?H⁰=19.375 kJ·mol^-1. It is inferred that the adsorption mechanism includes electrostatic adsorption, redox and ion exchange.

Key words: ultrasound, composites, functionalized Fe₃O₄, absorption, Freundlich model, kinetics

摘要：

在超声波条件下先制得纳米Fe₃O₄颗粒，再在超声波辐照下一步合成氨基、亚氨基和磺酸基修饰的功能化磁性纳米复合材料Fe₃O₄-mPD/SP（50∶50），采用TEM、XRD、IR、TGA、VSM及BET对其进行表征，考察了其对Cr(Ⅵ)的吸附性能，结果表明：溶液pH对Cr(Ⅵ) 吸附影响显著，pH=2时，吸附效果最好；吸附剂投加量、竞争性阴离子（Cl^-，NO₃^-，SO₄^2-）、温度等均会对吸附Cr(Ⅵ) 造成一定影响。等温吸附数据符合Freundlich模型，K_F=34.464 mg^1-(1/n)·L^1/n·g^-1，n=3.861；对Cr(Ⅵ) 的吸附为自发过程，?G⁰<0，?S⁰=73.368 J·mol^-1·K^-1，?H⁰=19.375 kJ·mol^-1；准二级动力学方程能很好地描述Cr(Ⅵ) 在Fe₃O₄-mPD/SP（50∶50）上的吸附行为，k₂=1.324×10^-3 g·mg^-1·min^-1，q_e=77.157 mg·g^-1；推测出吸附机理包括静电吸附，氧化还原和离子交换。

关键词: 超声波, 复合材料, 功能化Fe₃O₄, 吸附, Freundlich模型, 动力学