氢氧化铝镁共干凝胶的组成确证

Determination of compositions of magnesium aluminum hydroxide co-dried gel

目的确证氢氧化铝镁共干凝胶的组成。方法采用化学分析、红外光谱分析和X-射线粉末衍射分析等手段。结果氢氧化铝镁中Al含量的质量分数为13.9%(相当于5.15 mol.kg-1),Mg含量的质量分数为15.1%(相当于6.21 mol.kg-1),C含量的质量分数为2.627%(相当于CO32-2.19 mol.kg-1);Al与Mg质量比约为1.2∶1;Al与CO32-质量比约为0.43∶1,与铝碳酸镁中Al和CO32-之比接近;通过X-射线粉末衍射测定氢氧化铝镁与铝碳酸镁的组成基本一致。结论氢氧化铝镁中Al与Mg之比值约为1.2,由Al与Mg比值可知氢氧化铝镁不是铝碳酸镁或镁加铝的混合物,也不是镁加铝和氢氧化铝的混合物,而应是铝碳酸镁与氢氧化铝的混合物。

Objective To determine the compositions of magnesium aluminum hydroxide co-dried gel. Methods Elemental analysis, IR spectrum and X-ray diffraction analysis were used to describe the composition. Results In magnesium aluminum hydroxide, the content of Al was 13.9 % （equate 5.15 mol· kg^-1）, Mg was 15.1% （equate 6.21 mol· kg^- 1 ）, C was 2. 627 % （equate CO3^2- 2.19 mol· kg^- 1 ）. The ratio of Al and Mg was about 1.2 ： 1, Al and CO3^2- was about 0.43 ： 1 which approaches the ratio in hydrotalcite. The composition of magnesium aluminum hydroxide was determined by X-ray diffraction analysis, and its composition was identical with that in hydrotalcite. Conclusions The ratio of AI and Mg is 1.2. The results demonstrate that magnesium aluminum hydroxide is the mixture of hydrotalcite and aluminum hydroxide.