高浓度氯化钙水热环境下氢氧化镁颗粒生长行为研究

Influence of high concentration CaCl_2 on morphology of Mg(OH)_2 particles in hydrothermal environment

以石灰乳-卤水法制备的氢氧化镁为原料,对不同水热环境下高浓度氯化钙对氢氧化镁颗粒形貌的影响进行了研究。通过扫描电镜(SEM)、X射线衍射仪和氮气吸附比表面积分析仪(BET)对产物的比表面积和形貌进行表征。结果表明,较高的温度和高浓度氯化钙的存在有利于晶体的发育生长,其产物的分散性较好,粒径均匀并呈六方片状晶体,比表面积由22.17 m2/g变为14.84 m2/g。对水热条件下氯化钙对晶体生长的作用进行了机理分析,CaCl2的存在使得氢氧化镁基元在晶体表面横向叠加,促进了六方片状氢氧化镁颗粒的生成,并提出氢氧化镁颗粒的最稳定晶型为六方片状。

The influence of high concentration CaCl2 on the morphology of Mg（OH）2 particles in different hydrothermal environments is investigated. The specific surface area （BET） and morphology of particles are respectively characterized by scanning electron microscope （SEM）, the powder X-ray diffractometer （XRD） and the nitrogen adsorption BET analyzer. The result shows that higher temperature and high concentration are favorable for the growth of crystal. The particles present better dispersibility and uniform particle size of hexagonal plates with the regular shape, and the specific surface area is reduced to 14.84 m^2/g from 22.17 m^2/g. The mechanism of influence of CaCl2 on the crystal growth is also discussed. The CaCl2 is favorable for the piling of Mg（OH）6^4- in radial direction and formation of hexagonal plate which is the most stable structure.