2014/02/14 by Matthew B. Pinson, Tingtao Zhou, Pinson, Matthew B. +5
Engineering · Materials Science · #FOS: Physical sciences #Hydrocarbon exploration and reservoir analysis #Materials Science (cond-mat.mtrl-sci) #Phase Equilibria and Thermodynamics #Pickering emulsions and particle stabilization #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.1402.3377
openalex publication_date 2014/02/14 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
Vapor adsorption experiments are widely used to assess pore size\ndistributions, but the large hysteresis sometimes observed between sorption and\ndesorption isotherms remains difficult to interpret. Such hysteresis is\ninfluenced pore network connectivity, which has previously been modeled by\npercolation on infinite lattices. Our hypothesis is that percolation occurs\ninstead through finite networks of micropores connecting accessible macropores,\nalways exposed to the outside environment. We derive a general formula for\nsorption/desorption isotherms that introduces a simple measure of hierarchical\npore connectivity -- the fraction f of always exposed pores. The model thus\naccounts for "small world" connections in finite-size percolation, while also\nincorporating other hysteresis mechanisms, in single-pore filling, liquid\ninsertion into the solid matrix, and cavitation. Our formula is able to fit and\ninterpret both primary and scanning sorption/desorption isotherms for a variety\nof adsorbates (noble gases, water, and organics) and porous materials (cement\npastes, dental enamels, porous glasses, carbon black and nanotubes), including\ncases with broad pore-size distributions and large hysteresis. It allows\nquantification of the prevalence of percolating macropores in the material,\neven though these pores are never filled during the sorption experiments. A\ndistinct bump in sorption isotherms is explained as a lowering of the barrier\nto nucleation of the vapor phase with a universal temperature scaling.\n