Chromatography mercury porosimetry

The porous structure of active carbons can be characterized by various techniques adsorption of gases (Ni, Ar, Kr, CO ) [5.39] or vapors (benzene, water) [5,39] by static (volumetric or gravimetric) or dynamic methods [39] adsorption from liquid solutions of solutes with a limited solubility and of solutes that are completely miscible with the solvent in all proportions [39] gas chromatography [40] immersion calorimetry [3,41J flow microcalorimetry [42] temperature-programmed desorption [43] mercury porosimetry [36,41] transmission electron microscopy (TEM) [44] and scanning electron microscopy (SEM) [44] small-angle x-ray scattering (SAXS) [44] x-ray diffraction (XRD) [44]. 

The pore size and distribution are defined by nitrogen adsorption (BET) or mercury porosimetry. In chromatographic terms, inverse size-exclusion chromatography (SEC) is particularly suitable, because only those pores are measured that are chromatographically available. 

Lubda, D., Lindner, W Quaglia, M., du Fresne von Hohenesche, C., Unger, K K., 2005. Comprehensive pore stmcture characterization of silica monohths with controlled mesopore size and macropore size by nitrogen sorption, mercury porosimetry, transmission electron microscopy and inverse size exclusion chromatography. J. Chromatography A 1083 14-22. 

The porous materials are known to be of importance in many different industrial processes e.g., catalysis, oil recovery, soil pollution, chromatography and separation. In all these systems, the pore structure is known to determine the physico-chemical characteristics. The pore shape and form is not easily determined. Microsporous material is not easily analyzed using electron microscope or diffraction methods, when the mean pore-radius is 2 -50 fjm. One generally uses mercury porosimetry for larger pores, which is based on a capillary phenomena. Other methods have also been used, which are based upon the effect of the curvature of a liquid on its solid - liquid phase transition equilibria, i.e. freezing point depression, vapor pressure or heat of evaporation. 

In this work solid-gas chromatography is used to measure dynamic diffusion coefficients of argon in various porous solids. Mercury porosimetry is used to study the internal macroporosity and macro-morphology of these solids. Finally, an attempt is made to elucidate a relationship between the tortuosity measured from the transport experiment and the internal structure of the porous medium as characterized by porosimetry. 

Determination of the morphology of the original polymers and the SIRs obtained from them by impregnation is very helpful in elucidation of the adsorption mechanism of the extractant. The results of specific surface area determinations, mercury intrusion porosimetry, and inverse steric exclusion chromatography (ISEC) were used to determine the different mechanism involved in extractant retention in the polymer phase as a function of the polymer structure and the type of mechanism involved in the retention (1) physical adsorption or (2) chemical interaction. 

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