富镁与贫镁坡缕石的红外光谱

Infrared Spectroscopic of Mg-rich and Mg-poor Palygorskite

研究了安徽明光富镁坡缕石和江苏盱眙贫镁坡缕石及其热处理产物的红外光谱特征(尤其是中低频区域),结果表明:坡缕石的红外光谱特征峰为1 196 cm-1(连接倒转SiO4四面体的Si—O—Si非对称伸缩振动),647 cm-1(与孔道边缘MgO6八面体配位的结晶水相关的H2O—Mg—OH2振动)。由于八面体中阳离子占位差异,垂直的Si—O—M(Ⅵ)非对称伸缩振动与对称伸缩振动峰在盱眙贫镁坡缕石中分别出现在998cm-1和685cm-1,明光富镁坡缕石中则分别显示为987 cm-1和680 cm-1,而且富镁的坡缕石一般出现特征峰3 687 cm-1(Mg3—OH伸缩振动)。此外,明光富镁坡缕石样品中存在的865cm-1峰应为杂质无定形碳酸盐的CO32-弯曲振动。

The infrared spectra of the Mg-rich palygorskite from Mingguang, Anhui Province, and Mg-poor palygorskite from Xuyi, Jiangsu Province under heating were investigated. Palygorskite is characterized by two bands at 1 196 and 647 cna-1, which are attributed to the asymmetric stretching vibration of the Si-O-Si group that connects the adjacent inverse SiO4 tetrahedrons and the 1-120-- Mg--H2O stretching vibration in the MgO6 octahedra at the edges of the channels, respectively. The structures of the Mg-rich and Mg-poor of palygorskite are different mainly in the occupied sites of the octahedral cations. The symmetric and asymmetric stretching of perpendicular Si--O--M （VI） appears at 998 cm-1 and 685 cm-1 in the IR spectra of XY-Pal rather than at 987 cm-1 and 680 cm-1 in the IR spectra of sample MG-Pal. The band at 3 687 cm-1 for Mg-rich palygorskite is attributed to Mg3-OH stretching vibration. Moreover, the band at 865 cm-1 is assigned to the CO32- bending vibration of amorphous carbonate.