蒙脱石具良好的阳离子可交换吸附特性。在提纯蒙脱石的基础上，用氯化铵（NH4 Cl）和十六烷基三甲基溴化铵（CTAB）分别交换蒙脱石层间阳离子制备了改性蒙脱石，并用提纯蒙脱石、改性后的蒙脱石吸附碱式硫酸铬溶液中的铬离子，获得含铬蒙脱石样品。针对上述的含铬蒙脱石进行包括粉末X射线衍射术（XRD）、电子顺磁共振谱术（EPR）和傅里叶变换红外吸收光谱术（FTIR）以及电感耦合与等离子体原子发射光谱（ICP-AES）等测试和分析。吸附残余液的化学分析结果和含铬蒙脱石样品的XRD结果显示CTAB对蒙脱石的层间的封闭是较完全的，层间几乎未发生交换吸附；而NH＋4—蒙脱石和蒙脱石层间则发生交换吸附。吸附前后样品的红外吸收谱发生了较大变化，表明三个含铬样品的红外吸收谱上出现的硅醇和铝醇向低波数延展的现象是由铬离子吸附在蒙脱石结构片的六方孔中所致。EPR的结果指示甚至在蒙脱石的少量四面体和／（或）八面体位中也有Cr3＋占位。%Objective:Montmorillonite has a good property of cation exchanging and adsorbing.According to purified montmorillonite properties,modified samples were prepared by using NH4 Cl and Hexadecyl trimethyl ammonium Bromide (CTAB)to exchanging the interlayer cation,respectively.Subsequently,the modified montmorillonites were used to adsorb Cr3+ ions in the chromium sulfate solution. Then,the obtained chromium bearing montmorillonites were analyzed and tested.The techniques of testing include powder X-ray diffractometry (XRD), Electron Paramagnetic Resonance (EPR)spectrometry and Frourie Transform Infrared (FTIR)spectrometry.The chemical analysis of residual solution show that the CTAB effectively closed the interlayer region of montmorillonite and hindered the Cr3+to occupy this region.However,the Cr3+exchange occurred in NH+4 -montmorillonite and purified montmorillonite.Samples before and after the adsorption of FTIR spectra had significant changes occurred, These suggested that extending to the lower bands in the region of silanol and aluminols in the FTIR spectra resulted from the adsorption mainly occurred in hexagonal cavities of TOT sheets.EPR results also suggested that even a small amount of octahedrons or tetrahedrons. Methods:We used purified montmorillonites and modified montmorillonites to adsorb Cr3++ions in the chromium sulfate solution(0.1mol/L),modified samples were prepared by using NH4Cl and Hexadecyl trimethyl ammonium Bromide (CTAB)to exchanging the interlayer cation.The techniques of testing include powder X-ray diffractometry (XRD),Electron Paramagnetic Resonance (EPR)spectrometry and Frourie Transform Infrared (FTIR)spectrometry were used to study the obtained chromium bearing montmorillonites. Results:The results show before Cr-adorbsorption,the CTAB and NH+4 ions were used to exchange the interlayer cations and the 001 diffraction line shifts from 1.54nm to 2.28 and 1.25nm,respectively.After Cr-absorption,001 reflection of no exchanged and NH4+-exchanged to 1.55nm,the one of CTAB-exchanged kept stead at 2.28 nm.These may suggest that the Cr3+can not exchange the CTAB and may be present the surface of the montmorillonite grains or into the hexagonal cavities of TOT sheets.In first derivative EPR spectra,the intensity of peak centered at g=2.00 increased with the amount of Cr-adsorbed at room temperature.Very slight increase for Cr—CTAB-M and one weak peak at g=1 .98 in second derivative spectra,huge increase for Cr-M and Cr—NH+4 -M.It may suggest that the g =1.97 peak resulted from the [Cr(6H2O)]3+ions in interlayer space or Cr3+in octahedral sheets. Conclusions:Heating can impulse the Cr3+entering the hexagonal cavities and then octahedral sites.Cr3+can exchange the interlayer NH+4 ions,but cannot exchange the CTAB ions.Hence,the CTAB cations protected the interlay regions when the Cr3+adsorbing.It encouraged the Cr3+enter into either hexagonal cavities or octahedral sites.
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