Understanding the diffusional tortuosity of porous materials: An effective medium theory perspective

摘要: The interpretation of experimental data on transport in porous materials is often based the use a single representative pore size, overlooking effects size distribution (PSD) and network connectivity, fitting tortuosity into which all such uncertainties are consigned. Using literature diffusion N2, Xe i-C4H10 mesoporous Shell silica spheres, we demonstrate that depends choice radius as well gas species. Both Knudsen model Oscillator considering dispersive fluid–solid interactions, developed this laboratory, found to adequately interpret conjunction with effective medium theory (EMT) by coordination number instead tortuosity. This insensitivity due large mean mesopore 7.4 nm for silica; however, yield value closer range values expected material. EMT dependent temperature diffusing species, because differences dependence between conductance at true connectivity PSD. In slip flow regime, obtained show superposition viscous mechanisms leads species tortuosity, different two contributions. limiting tortuosities PSD regimes. These critical aspects largely unappreciated literature, even systematic variations or usually overlooked, leading misrepresentation underlying mechanism.