磁性高岭土的制备及对铅离子的吸附

采用共沉淀法制备磁性高岭土，以扫描电子显微镜（SEM）、能量色散X 射线光谱（ EDX）、红外光谱（FTIR）和X射线衍射（XRD）对其进行表征。分析了吸附剂用量、pH、时间对磁性高岭土吸附Pb2+的影响，并与Fe3O4和高岭土的吸附性能进行比较。SEM表明制备的磁性高岭土为大小不均匀的细小颗粒，XRD结果表明磁化后，高岭土的晶体结构改变不大，EDX表明磁化后，Si、Al元素的含量基本不变，O元素含量有所增加，且出现了Fe元素的波峰，FTIR表明磁化后出现了Fe-O的特征吸收峰；吸附实验结果表明在20 min内达到吸附平衡，在Pb2+浓度为5.0 mg·L-1时，去除率达到99.38%。磁性高岭土对Pb2+的吸附性能高于Fe3O4和高岭土的吸附性能，Langmuir模型能更好的描述Pb2+在磁性高岭土上的吸附平衡，对Pb2+为优惠吸附。Pb2+的吸附行为更符合拟二级动力学方程，说明Pb2+在磁性高岭土上的吸附过程主要由化学吸附控制。

Synthesis of magnetic kaolin and adsorption of lead(II)

Magnetic kaolin clay was prepared by a co-precipitation process, and the resulting adsorbent was analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The effects of adsorbent dose, pH, and adsorption time on the magnetic kaolin adsorption behavior were determined. Its adsorption properties were also compared with kaolin and Fe3O4. SEM results indicated that magnetic kaolin was composed of very small particles of different sizes, while XRD indicated that the kaolin crystal structure remained unchanged. In addition, EDX showed that the Si and Al contents remained constant, while that of O increased, with FTIR results demonstrating the presence of characteristic Fe-O absorption peaks. The adsorption process reached an adsorption equilibrium within 20 min, giving an adsorption rate of 99.48% with an initial Pb2+ concentration of 5.0 mg·L-1. Furthermore, the adsorption properties of magnetic kaolin were superior to those of both Fe3O4 and kaolin. The adsorption of Pb2+ on magnetic kaolin was well described by the Langmuir adsorption model, with the system exhibiting preferential adsorption. Finally, the adsorption kinetics fit the pseudo-second-order kinetic model, indicating that Pb2+ adsorption on magnetic kaolin was controlled mainly by chemical adsorption.