液相沉淀法制备镁铝水滑石及其表征

The preparation and characterization of magnesium-aluminium hydrotalcite by liquid coprecipitation method

采用液相沉淀法以AlCl3·6H2O，MgCl2·6H2O，Na2CO3，NaOH为原料，制备镁铝水滑石。研究结果表明水浴70、80、90℃加热时均能制备出纯净的镁铝水滑石，从热重分析可知镁铝水滑石有两个失重阶段，第一次热分解起始点约为173℃失重约15％，释放出镁铝水滑石中间层的4个结晶水，第二次热分解起始点约为352℃失重约30％，中间层中的碳酸根离子以二氧化碳的形式放出，同时羟基分解产生水。镁铝水滑石晶粒呈不规则的六边形，晶粒大小约在为30～70nm之间。

Magnesium-aluminium hydrotalcites were prepared by liquid coprecipitation method with AlCl3·6H2O,MgCl2·6H2O,Na2CO3,NaOH as raw materials. The XRD results show that pure magnesium-aluminium hydrotalcite can be prepared at the water bath of 70, 80 and 90℃. There are two stages of weight loss in the TG curves, The first thermal decomposition begins at 173℃ with the weight loss of 15%, which dues to the release of the four cyrstal water. The second thermal decomposition begins at 352℃ with the weight loss of 30% as a result of the release of the carbon dioxide and the water decomposed from hydroxyl. The TEM images show that the grains of magnesium-aluminium hydrotalcite present irregular hexagon and the grain size is between 30 nm and 70nm.