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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Pb~(2+)的影响,并与Fe_3O_4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Pb~(2+)浓度为5.0 mg·L~(-1)时,去除率达到99.38%。磁性高岭土对Pb~(2+)的吸附性能高于Fe_3O_4和高岭土的吸附性能,Langmuir模型能更好的描述Pb~(2+)在磁性高岭土上的吸附平衡,对Pb~(2+)为优惠吸附。Pb~(2+)的吸附行为更符合拟二级动力学方程,说明Pb~(2+)在磁性高岭土上的吸附过程主要由化学吸附控制。
Magnetic kaolin was prepared by coprecipitation method and characterized by SEM, EDX, FTIR and XRD. The effects of adsorbent dosage, pH and time on the adsorption of Pb ~ (2+) on magnetic kaolinite were analyzed and compared with that of Fe_3O_4 and kaolin. SEM showed that the prepared magnetic kaolin was a non-uniform size small particle. The XRD results showed that the crystal structure of kaolin did not change much after magnetization. EDX showed that the contents of Si and Al remained unchanged and the content of O increased after magnetization. And the peak of Fe element appeared. The FTIR showed that the characteristic absorption peak of Fe-O appeared after magnetization. The adsorption experiment showed that the adsorption equilibrium reached within 20 min and the concentration of Pb 2+ was 5.0 mg · L ~ (-1) 1), the removal rate reached 99.38%. The adsorption capacity of magnetic kaolin to Pb 2+ is higher than that of Fe 3 O 4 and kaolin, Langmuir model can better describe the adsorption equilibrium of Pb 2+ on magnetic kaolin, Preferential adsorption. The adsorption behavior of Pb 2+ is more in line with the pseudo second-order kinetic equation, indicating that the adsorption of Pb 2+ on magnetic kaolin is mainly controlled by chemisorption.