水热条件下凹凸棒石黏土与Mg^(2+)的反应

Reaction of Mg^(2+) and Palygorskite under Hydrothermal System

凹凸棒石在水热条件下的稳定性,尤其是如何实现水热条件下凹凸棒石的生长,是凹凸棒石黏土研究中十分值得关注的重要问题。考察了不同浓度氯化镁、氢氧化镁在不同配比、不同温度及反应时间下与凹凸棒石的作用,探讨镁化合物类型、水热反应温度和时间对凹凸棒石稳定性和晶体生长的影响。凹凸棒石黏土中加入不同配比镁化合物在75~200℃区间水热反应后的样品的透射电子显微镜、X射线衍射分析结果表明:凹凸棒石在纯水系统中基本稳定,晶体结构、晶体形貌、结晶度不发生明显的变化;碱性镁化合物即氢氧化镁的加入促使凹凸棒石转化为蒙皂石或者蛇纹石;中性的镁盐加入有利于凹凸棒石晶体的生长,但是凹凸棒石晶体的生长十分缓慢。

The stability of palygorskite, especially the growth of palygorskite under hydrothermal conditions, is an important aspect in palygorskite clay studies. The reaction at different proportions and concentrations of MgCl2 · 6H2O/Mg（ OH）2 was investigated. The influences of parameters （i. e. , magnesium compounds types, temperatures and reaction time） on the palygorskite stability and crystal growth were discussed. The results obtained by transmission electron microscopy, X-ray diffraction of the samples after reacted with different magnesium compounds at different proportions of hydrothermal systems at 75--200 ℃ show that the palygorskite is stable in aqueous solution. The crystal structure, crystal morphology, crystallinity do not change. The alkaline magnesium compound （Mg（OH） 2 ） promotes the transformation of palygorskite into smectite or serpentine, and the addition of neutral magnesium compound （MgCl2 ） will favor the growth of palygorskite crystal, hut affect the growth rate.