Co(Ⅱ)在磁性埃洛石上的吸附行为研究

Adsorption performance of Co(Ⅱ) on magnetic halloysite

采用化学共沉淀法成功制备了磁性埃洛石,运用扫描电子显微镜(SEM)、红外光谱仪(FT-IR)、X射线衍射仪(XRD)和振动样品磁强计(VSM)等手段详细表征了改性前后埃洛石的结构和形态,并采用静态批量平衡法对Co(Ⅱ)在磁性埃洛石上的吸附行为和机理进行探究,考察了料液比、平衡时间、p H值和温度等因素对吸附的影响.实验结果表明:温度为50℃时,Co(Ⅱ)在磁性埃洛石上的最大吸附容量为17.5mg·g-1.p H<7.5时,随着p H增加,吸附量增大;当p H=7.5时,吸附量达到最大;以后即使p H增大,吸附量也不会明显变化.动力学过程符合准二级动力学方程;热力学过程符合Langmuir吸附等温线;升高温度利于Co(Ⅱ)在磁性埃洛石上吸附.

Magnetic halloysite composite was successfully synthesized by chemical precipitation method. The structure and morphology of halloysite and magnetic halloysite composite were characterized by scanning electron microscope（ SEM）,X-ray diffraction（ XRD）,fourier transfer infrared（ FT-IR）and vibrating sample magnetometer（ VSM）. The adsorption of Co（ Ⅱ） on magnetic halloysite as function of material liquid ratio,p H,time and temperature under ambient conditions was investigated using static experimental method. The as-obtained results show that the maximum adsorption capacity is 17. 5 mg·g- 1at 50 ℃. The adsorption of Co（ Ⅱ） on magnetic halloysite is strongly dependent on p H and temperature. When p H is less than7. 5,the adsorption capacity increases with the increase of p H and then reaches the steady state. The adsorption data of Co（ Ⅱ） on the magnetic halloysite are well consistent with the Lagrange pseudo-second-order kinetic model. Adsorption of Co（ Ⅱ） on the magnetic halloysite fits the Langmuir isotherm well. It is found that the adsorption capacity increases dramatically with the increase of temperature.