Fluid Adsorption and Transport in Nanoporous Materials

Nanoporous materials are at the heart of numerous important applications: adsorption (gas sensing, drug delivery, chromatography), energy (hydrogen storage, fuel cells and batteries), environment (phase separation, water treatment, nuclear waste storage), Earth science (exchange between the soil and the atmosphere), etc. In this talk, I will present the state-of-the-art on adsorption/condensation and transport in nanoporous materials which possess pore sizes spanning several orders of magnitude (from the sub-nm scale to a few tens of nm).^1,2 I will first discuss the different adsorption regimes encountered when a fluid is set in contact with a porous material: from irreversible adsorption/capillary condensation for the largest pores to reversible/continuous filling for the smallest pores. We will see that simple thermodynamic modeling allows rationalizing these different regimes provided that a description of the shift of the critical point of the confined fluid is taken into account. Then, I will show how transport in such media can be described without having to rely on macroscopic concepts such as hydrodynamics.^3,4,5 Using parameters and coefficients available to experiments, we will see how transport coefficients can be rigorously obtained from simple models in the framework of Statistical Mechanics using models such as free volume theory and intermittent brownian motion.

¹ B. Coasne et al., Chem. Soc. Rev. 42, 4141 (2013).
² B. Coasne, New J. Chem. 40, 4078 (2016).
³ K. Falk et al., Nature Comm. 6, 6949 (2015).
⁴ A. Botan et al., Phys. Rev. E. 91, 032133 (2015).
⁵ T. Lee et al., Nature Comm. 7, 11890 (2016).