碱式氯化镁5Mg(OH)2·MgCl2·3H2O的制备与表征

以氨水和盐湖盛产的水氯镁石为原料经过两步反应制备碱式氯化镁.第一步,水氯镁石和氨水反应制备氢氧化镁;第二步,利用氢氧化镁和水氯镁石,通过水热反应得到了具有纤维形貌、结晶较好的碱式氯化镁.应用化学分析、XRD、SEM和FIIR等手段对产物进行测试与表征.化学分析结果表明产物组成为5Mg(OH)2·MgCl2·3H2O.将得到的5Mg(OH)2·MgCl2·3H2O和碱式氯化镁系列标准XRD图对照,未有较好的匹配,且结合化学分析和已报道碱式硫酸镁具有5Mg(OH)2·MgSO4·3H2O物相,因而推测其为新物相;SEM图中5Mg(OH)2·MgCl2·3H2O纤维直径约为0.4μm,平均长度大于24 μm,长径比大于60;FTIR图谱中3419 cm-1附近出现了氢键的O-H伸缩振动吸收峰,1635 cm-1附近出现了游离水中H-O-H的弯曲振动吸收峰.水热合成的5Mg(OH)2·MgCl2·3H2O和常压下的产物相比直径较小,晶形更完整,强度更高.

Preparation and Characterization of Basic Magnesium Chloride 5Mg(OH)2-MgCIz. 3H20

Basic magnesium chloride with excellent crystal phase was prepared via hydrothermal synthesis using bischofite from salt lakes and ammonia. The product was obtained by two steps: (1) bischofite reacted with ammonia to form magnesium hydroxide; (2) the thus obtained magnesium hydroxide hydrothermally reacted with bischofite to form basic magnesium chloride, whose properties were characterized by chemical analysis, XRD, SEM and FTIR.The product has a composition of 5Mg(OH)2·MgCl2·3H2O as suggested by chemical analysis. The XRD pattern of the product can not match well with the standard PDF card, suggesting a new phase of 5Mg(OH)2-MgCl2·3H2O. The sample has a diameter of 0.4 μm, a mean length above 24 μm and an aspect ratio over 60 according to SEM analysis.FTIR analysis identifies an absorption band of hydrogen bonds O-H stretching vibration at 3 419 cm-1 and a free water H-O-H bending vibration absorption band at 1 635 cm-1, respectively. The 5Mg(OH)2·MgCl2·3H2O prepared by this method features smaller diameter, better crystal phase and higher strength compared to those prepared under atmospheric pressure.