Using diffusion measurements to determine pore-size distributions in porous materials

✍ Scribed by Lee F. Brown; Bryan J. Travis

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 487 KB
• Volume: 38
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(83)80004-9

✦ Synopsis

Abstrac-A

method for determining a type of pore-size distribution from diffusion measurements is presented. A Wick+Kallenbach experiment, for measuring diffusion fluxes within porous materials, is carried out over a significant portion of the transition range between Knudsen flow and bulk diflusion. If the internal porous structure of the material is modeled as myriad nonintersecting cylindrical pores, an equation may be deiived for the flux as a function of pressure, in which the flux is a functional of the pore-size distribution. The equation is a Fredbolm integral equation of the first kind. This is an application of the general inversion problem, and solution of the equation for the pore-size distribution is possible. It is demonstrated from calculated fluxes using postulated ideal distributions that the method works very well for both unimodal and bimodal distributions. The method is not extraordinarily sensitive to experimental error. The pore-size distribution obtained using this method embodies not only the sizes of the pores, but includes other properties affecting diffusion rates, such as pore shapes, directions, and interconnectivities.