NH2-MCM-41吸附剂的制备及其对铬离子(Ⅵ)吸附行为的研究

Synthesis of NH2-MCM-41 adsorbent and its adsorption behavior to Cr(Ⅵ)ions

采用水热合成法制备了MCM-41介孔分子筛,并利用3-氨丙基三甲氧基硅烷(APTMS)对其进行改性获得NH2-MCM-41分子筛。利用扫描电子显微镜、傅里叶红外光谱、氮气吸附-脱附测试、能量色散X射线荧光光谱仪和X-射线粉末衍射仪对NH2-MCM-41分子筛进行了表征。结果表明,氨基的修饰过程对MCM-41分子筛结构没有显著影响。以Cr(Ⅵ)为探针离子,研究了NH2-MCM-41分子筛对Cr(Ⅵ)的吸附性能,考察了NH2-MCM-41分子筛用量、吸附时间、pH和溶液初始浓度对吸附效果的影响。结果表明,与MCM-41分子筛对比,NH2-MCM-41分子筛对Cr(Ⅵ)具有更高的吸附性能。NH2-MCM-41对Cr(Ⅵ)的吸附过程符合准二级动力学模型和Langmuir等温吸附模型。该吸附剂具有良好的再生性能,重复使用5次,其吸附性能保持相对稳定。

MCM-41 mesoporous molecular sieves are prepared through hydrothermal synthesis method.NH2-MCM-41 molecular sieves are gained by modifying MCM-41 mesoporous molecular sieves with 3-aminopropyltrimethoxysilane(APTMS).Scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),nitrogen adsorption-desorption isotherm,energy dispersive X-ray spectroscopy(EDXS)and X-ray diffraction(XRD)analysis are utilized to analyze the detailed microstructure of the prepared NH2-MCM-41 molecular sieves.It is found that the modification by amino group has not significant impact on the microstructure of MCM-41 molecular sieves,which still maintains a typical mesoporous structure.The adsorptive ability of NH2-MCM-41 to Cr(Ⅵ)ions is studied.Effects of NH2-MCM-41 dosage,adsorption time,pH and initial concentration of Cr(Ⅵ)solution on the efficiency of adsorption are investigated,and the optimum adsorptive conditions are also confirmed.The results show that NH2-MCM-41 has a higher adsorptive ability to Cr(Ⅵ)than unmodified MCM-41.The adsorption behavior of NH2-MCM-41 to Cr(Ⅵ)conforms well with the pseudo-second order kinetics and Langmuir isotherm adsorption model.NH2-MCM-41 has an excellent regeneration performance.It can keep a relatively stable adsorption performance after being reused for 5 times.