富镁和贫镁坡缕石及其酸浸蚀产物的红外吸收光谱研究  

FTIR Spectra of Magnesium-rich, Magnesium-poor and Acid Leached Palygorskites

作　　者：蔡元峰[1] 薛纪越[1] 

机构地区：[1]南京大学地球科学系,210093

出　　处：《地质论评》2005年第1期92-99,共8页Geological Review

基　　金：国家自然科学基金项目 (编号 40 172 0 16)资助成果

摘　　要：本文对两个富镁和贫镁坡缕石的红外吸收光谱高频区的拟合结果表明 ,富镁坡缕石 (p0 )和贫镁坡缕石 (g0 )的八面体离子的配置有区别 ,前者除出现 Mg3OH振动外 ,Mg M2 □ OH振动的比例比 Al M2 □ OH振动的大 ,后者则反之。经酸短时间浸蚀的和未经浸蚀的坡缕石红外吸收光谱相比 ,除部分吸收峰 (如 35 6 0 cm- 1 )的峰形发生明显变化外 ,其余各吸收峰的峰形相似、强度稍有变化 ,且 Si U- O- Si D的不对称振动吸收峰向低波数方向偏移、对称吸收峰向高波数方向偏移 ;坡缕石中 790 cm- 1 左右的吸收峰的归属是不明确的 ,据实验确认它是由 Si U- O- Si D的对称吸收所致 ;由 985 cm- 1、10 30 cm- 1、10 80 cm- 1和 12 0 0 cm- 1左右 4个吸收峰组成 Si- O骨架振动吸收带的峰形、强度和峰位移反映了酸浸蚀过程中坡缕石的结构改变。两个坡缕石经 36 0 h盐酸浓度为 1m ol/ L 和 3m ol/ L 浸蚀后 ,所得产物的粉末 X射线衍射谱虽仍具有坡缕石的衍射线 ,但它们的红外吸收光谱却只有与表面 OH振动、物理吸附水相关的 OH振动和几个 Si O振动吸收峰 ,而无代表八面体振动、硅氧骨干中的大部分 Si O振动和晶格中的结晶水的振动 。The FTIR spectra of pure magnesium-rich and magnesium-poor palygorskites, short-time leached (<7 h) and 360 h leached palygorskites are involved in this paper. Comparison of decomposition spectra of pure magnesium-poor and magnesium-rich palygorskites clearly shows that octahedral cation pairs are different depending on their different chemical contents. The results show that most of vibrations of short-time leached palygorskite are similar to those of pure one except for 3685 cm -1 and 790 cm -1, and are slightly different in intensity and shape. The bands near 1200 cm -1 and 790 cm -1 are very sensitive to acid attack. As the acid attack progresses, the band at 1200 cm -1 shifts to lower wavenumbers, and the band at 790 cm -1 shifts to higher ones. The shift to higher and lower wavenumbers gives information of structural modification. The band near 790 cm -1 is assigned to Si U-O-Si D symmetrical stretching vibration. The disappearance of 900~1200 cm -1 absorption bands shows that the palygorskite has been eroded to amorphous silica. Sever vibrations are related to OH, i.e. 3390～3420, 3240～3290 and 847 cm -1, hygroscopic water (1635 cm -1), Si-O vibrations 1100, 611～621, 470～481 cm -1 etc. appear in the FTIR spectra of 360 h acid leached palygorskite. The bands resulting from octahedral and mostly vibrations of SiO skeleton disappear. Three bands near 1100, 611～621 and 470～481 cm -1 are related to Si-O vibration of the hexagonal (Si 2O 5)n sheet.

关 键 词：坡缕石 酸浸蚀 光谱研究 产物 红外吸收光谱 镁 X射线衍射谱 吸收峰 骨架振动 结构改变 盐酸浓度 八面体 SiO 高频区 峰形 不对称 吸收带 峰位移 吸附水 结晶水 强度 偏移 波数 

分 类 号：P619.2[天文地球—矿床学]