(644b) Quantifying Self-Diffusion of Mixed and Pure Organic Liquids in ZIF-Based Mixed Matrix Membranes By NMR
AIChE Annual Meeting
Thursday, November 17, 2022 - 12:51pm to 1:12pm
In this work, C-13 pulsed field gradient (PFG) NMR was used to quantify self-diffusion of pure and mixed xylene mixture inside zeolitic imidazolate framework-71 (ZIF-71) crystals dispersed in a Torlon polymer to form a ZIF-71/Torlon MMM. For the studied mixtures, selective C-13 isotopic labelling of each xylene isomer was used to ensure that the self-diffusivity of each isomer in the mixture is measured independently and correctly. The diffusion measurements were performed at different diffusion times. The observed time dependencies of intra-ZIF self-diffusivities were explained by an influence of the external crystal surface on the studied diffusion process. Analysis of these time dependencies measured for each xylene isomer allowed obtaining intra-ZIF self-diffusivities not perturbed by crystal surface effects as well as the corresponding diffusion selectivity for the studied sorbate mixture. These results will be presented and discussed in detail. The reported selectivity demonstrates promising separation behavior of the considered membrane type.