气体吸附法测定二氧化硅干凝胶的分形维数

提出了一种方便、科学有效的利用气体吸附法测定二氧化硅干凝胶等多孔材料分形维数（表面分形维数和孔分布分形维数）的方法，不需要进行一系列的吸附/脱附实验，只需要利用单一气体的一次吸附/脱附实验得出的样品孔分布、比表面数据，与不同的标尺进行关联，即可同时获得表面分形维数和孔分布分形维数.通过误差分析和校正，保证了结果的可靠性.用上述方法测定了二氧化硅干凝胶的分形维数，以FHH法和SAXS法对所得结果进行了比较和验证，并对吸附/脱附过程所得结果的差异进行了初步分析. 关键词： 分形维数 气体吸附 二氧化硅 干凝胶

Determination of fractal dimensions of silicon dioxide xerogel by means of gas-adsorption

Analysis of the structure of most irregular porous materials has recently been developed on the basis of the concepts of fractal geometry. The geometry enables general statements about so-called irregular structures to be made in terms of a few well-defined mathematical ideas,e.g. self-similarity and scaling,and a few mathematical parameters,e.g. fractal dimension. Gas adsorption is an ideal tool for characterization of the pore structure of xerogels and other porous materials. In this short paper,a simple and effective method to determine the fractal dimension of xerogels is presented. Instead of carrying out a series of gas adsorption/desorption experiments with various gases,only one gas adsorption/desorption experiment using a kind of gas is needed here. By studying the relations between the scaling and the data of pore size distribution and specific surface area,both surface fractal dimension and pore distribution fractal dimension can be easily derived. The reliability of the results is realized by performing error analysis and correction. The effectivity of the method is tested by experimental N 2 adsorption/desorption data of silica xerogels prepared with sol-gel routine.