An in-situ Pore-Size Distribution Determination Technique Based on the Capillary Phase Separation in Liquid Phase

我们开发了一种用于测定浸没多孔固体的孔径分布的技术，该多孔固体可以在液体中溶胀，如其在浸没状态中所示。在该技术中利用了毛细管相分离，或甚至在低于饱和浓度的浓度下在细孔内的相分离。我们可以从测量的合适溶质或探针分子的液相吸附等温线计算原位孔径分布。通过研究，得到以下主要结论：1.测定了几种多孔固体对水溶液中芳香族化合物的液相吸附等温线。还测量了固体的氮等温线以获得它们的表面积和孔径分布。2.采用与多孔固体具有相同化学组成的无孔固体来获得这些固体在液相中的表面吸附量。还测量了氮吸附等温线。3.根据上述数据，由液相吸附数据和氮吸附数据计算孔径分布。这两种分布吻合得很好，证明了本技术的有效性。4.已经进行了一些研究，以刷这一技术的应用程序膨胀/收缩材料。我们发现，所谓的无模型方法可以找到合理的孔径特征，即使没有数据的表面吸附。5.环烷烃尤其是环戊烷是合适的探针分子。6.除水相体系外，该技术已被证明在某些非水相溶剂体系中也是有效的。总之，通过本研究项目建立了一种原位测量液体中多孔固体孔径分布的技术，这是传统方法如氮气吸附法和压汞法无法检测到的。

We developed a technique for the determination of pore-size distribution of immersed porous solids, which may swell in liquid, as it shows in the immersed state. The capillary phase separation, or a phase separation within fine pores even at a lower concentration than the saturated concentration, was utilized in the technique. We can calculate an in-situ pore size distribution from a measured liquid-phase adsorption isotherm of a suitable solute, or a probe molecule. Through the research, the following was concluded.1.Liquid-phase adsorption isotherms of some aromatic compounds from aqueous solution onto some porous solids were measured. Nitrogen isotherms of the solids were also measured to obtain their surface areas and pore size distributions. 2.Nonporous solids which have the same chemical composition as those of porous solids were employed to obtain the amount of surface adsorption in liquid phase onto these solids. Nitrogen adsorption isotherms were also measured. 3.From the data mentioned above, pore size distributions were calculated both from liquid phase adsorption data and from nitrogen adsorption data. The two distributions agreed well to prove the validity of the present technique. 4.Some studies have been carried out to brush up this technique for the application to swelling/shrinking materials. We have found the so-called Modelless Method can find pore size characteristics reasonably even if no data of surface adsorption is available. 5.Further, suitable probe molecules were found to be cyclic alkanes, especially cyclopentane. 6.Other than aqueous systems, this technique has been proven to be effective in some systems with non-aqueous solvents.Summarizing, a technique to measure in-situ pore size distribution of porous solids in liquid, which could never been detectable by conventional methods such as nitrogen adsorption and mercury porosimetry, has been established through this research project.