Application of FTIR Technique in Microwave-Hydrothermal Synthesis of Saponite
YAO Ming1, 2, LIU Zi-yang2, WANG Kai-xiong1, ZHU Miao-qin2,SUN Hong-jie2
1. College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310029, China 2. Department of Chemistry, Zhejiang University, Hangzhou 310027, China
Abstract:FTIR was employed in the structure analysis of the saponites with an ideal chemical formula[Si6.5Al1.5]Ⅳ[Mg6]ⅥO20(OH)4 in the starting gel synthesized by microwave-hydrothermally under different pressures (1×105, 5×105, 1.5×106, 2.5 ×106 and 3.5×106 Pa). It was found that low frequency absorption region in infrared spectrum was sensitive to the crystallization of the product and the amorphous materials produced in synthesis of saponite under the radiation of microwave. The absorptions belong to amorphous materials were decreased with increasing pressure. Saponite synthesized at 3.5×106 Pa showed no amorphous absorptions (1 240, 590-602 cm-1), indicating the purity and quality of the synthetic mineral. It was worthy to note that Si(Al)—O stretching vibration infrared absorption could be regarded as an index in assessing the quality of synthetic 2∶1 trioctahedral smectite sample with the same chemical compositions. With the increasing pressure, this strong vibration shifted to low frequency (1 022, 1 020, 1 016, 1 016, 1005 cm-1) in the medium frequency of the whole infrared spectrum. Since the sensitivity, easiness and simplicity, this infrared index would be meaningful in practical saponite-related minerals analysis. In addition, powder X-ray diffraction and scanning electronic microscopy were employed in charactering the saponite synthesized by microwave-hydrothermal method in this work.
[1] LIU Zi-yang, JIANG Da-zhen, ZHANG Ai-jun,et al(刘子阳, 蒋大振,张爱君,等). Chem. J. Chin. Univ.(高等学校化学学报), 1991, 12(4): 502. [2] WEN Lu, LIANG Wan-xue, ZHANG Zheng-gang, HUANG Jin-chu(闻 辂, 梁婉雪,章正刚,黄进初). The Infrared Spectroscopy of Minerals(矿物红外光谱学). Chongqing:Chongqing University Press(重庆:重庆大学出版社), 1988. [3] ZHAO Dong-yuan, YANG Ya-shu, XIN Qin,et al(赵东源,杨亚书,辛 勤,等). Spectroscopy and Spectral Analysis(光谱学与光谱分析),1994, 14(4): 27. [4] WU Jing-gui, XI Shi-quan, JIANG Yan(吴景贵, 席时权, 姜 岩). Spectroscopy and Spectral Analysis(光谱学与光谱分析),1998, 18(1): 52. [5] Kloprogge J T and Frost R L. Vibrational Spectroscopy, 2000, 23: 119. [6] Li L S, Liu X S, Ge Y,et al. Journal Physical Chemistry, 1993, 97: 10389. [7] Wilson M J. A Handbook of Determinative Methods in Clay Mineralogy, Blackie & Son Ltd, 1987. [8] Post J L. Clays Clay Miner, 1984, 32(2): 147.