季铵盐与烷基胺插层高岭石结构及其热动力学对比

Structure and Thermodynamic Comparison of the Kaolinite Alkylamine and Quaternary Ammonium Salt Intercalation Complexes

采用X射线衍射、Fourier变换红外光谱及热分析等表征方法对高岭石/十二烷基三甲基氯化铵(Kaol-DTAC)及高岭石/十二胺(Kaol-DA)插层复合物的结构进行对比研究,并进一步研究了插层复合物的热动力学。结果表明:插层作用使高岭石在加热过程中脱羟基温度降低了10℃左右。由于插层分子DTAC与DA的结构差异,致使其在高岭石层间的排列方式存在差异。前者主要以呈90°夹角垂直于高岭石晶层面的方式单层排列,后者则以分子链与高岭石晶面呈39.9°夹角双层倾斜排列为主,且二者在高岭石层间排列方式的不同导致其结构稳定性存在差异。采用KAS法和Ozawa法对Kaol-DTAC和Kaol-DA插层复合物进行热力学分析并且分别计算其活化能。Kaol-DTAC的活化能为102.44 k J/mol,Kaol-DA的活化能为130.80 k J/mol,进一步说明DA比DTAC在高岭石层间更为稳定。

The intercalation complexes of kaolinite/dodecyl trimethyl ammonium chloride(Kaol-DTAC) and kaolinite/dodecylamine(Kaol-DA) were compared and studied by using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry analysis, and the thermodynamic of the intercalation complexes was further studied. The intercalation made the temperature of dehydroxylation of kaolinite reduced by approximately 10 ℃ during the heating process. There is a difference in the arrangement of DTAC and DA in kaolinite interlayer space which is due to the structure difference between DTAC and DA molecules. The former is mainly arranged in a single layer with an angle of 90° perpendicular to the level of kaolinite crystals while the latter is tilted to the kaolinite surface in bilayer and the inclination angle of the chains is 39.9° and the different agreements in kaolinite interlayer space result in differences in their structural stability. The activation energy was calculated by using KAS and Ozawa methods to thermodynamic analysis for the composites of Kaol-DTAC and Kaol-DA. The activation energy E of Kaol-DTAC is 102.44 kJ/mol and the activation energy E of Kaol-DA is 130.80 k J/mol which further shows that DA is more stable than DTAC between kaolinite interlayer space.