磁性ZnFe_2O_4/埃洛石复合材料的结构及吸附性能研究

Structure and Adsorption Property of Magnetic ZnFe_2O_4-halloysite Composite Material

采用溶胶-凝胶法制备磁性ZnFe_2O_4/埃洛石复合材料(MHNTs),并对其吸附亚甲基蓝(MB)的性能进行研究。利用X射线衍射仪(XRD)、透射电子显微电镜(TEM)、傅里叶变换红外光谱仪(FT-IR)和振动样品磁强计(VSM)等对MHNTs的结构、形貌和磁性能进行表征,采用静态批量平衡法对MB在MHNTs上的吸附行为和机理进行探究,并考察了初始浓度、吸附时间和温度等因素的影响。结果表明:复合材料中ZnFe_2O_4以10~30 nm尖晶石型纳米粒子沉积到埃洛石纳米管表面,通过谢乐公式计算纳米ZnFe_2O_4的晶粒尺寸为19.1 nm;MHNTs具有良好的顺磁性和磁回收性。MHNTs对MB的吸附行为符合准二级动力学方程,其吸附热力学过程符合Langmuir吸附等温线;温度对MB在MHNTs上的吸附影响较大,且升高温度有利于MHNTs对MB的吸附。此外,MHNTs可通过磁外场有效回收,经过5次重复使用后MHNTs对10 mg/L MB溶液的吸附性能基本没有下降。

Magnetic ZnFe2O4/halloysite composite （MHNTs） was synthesized by Sol-Gel process and its sorption behavior towards methylene blue （MB） was studied. Structure, morphology and magnetic property of MHNTs were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM）, fourier transfer infrared （FT-IR）, and vibrating sample magnetometer （VSM）. Static batch equilibrium method was used to investigate the adsorption behavior and mechanism of MB on MHNTs. The results show that ZnFe2O4 composites with 10-30 nm spinel type nanoparticles are well loaded on the surface of HNTs. The average grain size of nano-ZnFe2O4 is 19.1 nm calculated by Scherrer equation. MHNTs exhibit good paramagnetic and magnetic recovery properties. MB sorption of MHNTs follows pseudo-second order kinetic model and Langmuir thermodynamics model. MB sorption process is strongly affected by temperature, and higher temperature is beneficial for the adsorption of MB by MHNTs. Furthermore, MHNTs can be recovered effectively by magnetic field and the adsorption properties of MHNTs on 10 mg/L MB solutions hardly decreased after 5 times of repeated use.