Topological analysis of non-granular, disordered porous media: determination of pore connectivity, pore coordination, and geometric tortuosity in physically reconstructed silica monoliths
Abstract
Gaining adequate knowledge on the morphology of porous media is critical to ensuring their continued success as support structures in applications that rely on efficient mass transport. The physical reconstruction of a porous medium provides the optimum basis for an accurate characterization of its morphology, yet the identification of meaningful descriptors is not straightforward, especially not for monolithic materials, whose continuous solid phase and open pore network resist the tessellation schemes applicable to granular media. In this work, we focus on a hardly investigated component of silica monolith morphology, namely the topology of the hydrodynamically accessible macropore space. We propose and apply suitable methods to determine pore connectivity, pore coordination, and geometric tortuosity in four silica monolith samples after physical reconstruction of their macropore space by confocal laser scanning microscopy. Pore connectivity is traced by medial axis analysis, whereas pore coordination is evaluated after compartmentalization of the open macropore space into individual pores and pore throats by a maximum inscribed spheres approach. The geometric tortuosity is determined by medial axis analysis as well as by a propagation method that maps the geodesic distance from the center point of a reconstruction to every other point in the pore space. The presented results provide a comprehensive description of silica monolith topology as well as quantitative data for the construction of pore network models. The proposed analysis methods are applicable to any porous material that can be physically reconstructed at the required resolution.
- This article is part of the themed collection: The Creative World of Porous Materials