Meso-scale simulation on mechanism of Na+-gated water-conducting nanochannels in zeolite NaA

CL Qiu and SW Deng and X Sun and YJ Gao and ZH Yao and GL Zhuang and SB Wang and JG Wang, JOURNAL OF MEMBRANE SCIENCE, 635, 119462 (2021).

DOI: 10.1016/j.memsci.2021.119462

Na+-gated water-conducting nanochannels was created in previous work by assembling NaA zeolite crystals into a specialized membrane for sieving water from small gas molecules such as H2 and CO2. The quantum mechanics calculation provides only the reaction or adsorption information which are insufficient to understand the mechanism for the entire separation process. Herein, in addition to the density functional theory calculations, we illustrated the molecular sieving mechanism of Na+-gated water-conducting nanochannels in zeolite NaA by molecular simulations (grand canonical Monte Carlo and molecular dynamics simulations). The result shows that Na+ in water channel plays an important role in rejecting other gas molecules (H2 and CO2), and water molecule can pass through the channel easily due to its strong adsorption with zeolite NaA and low energy barrier for penetration. Moreover, simulation result shows that the diffusion path of H2O molecule in the zeolite NaA is not directly passing through the alpha- cages, but jumping between adjacent 8-oxygen rings. The proposed mechanism of water-conducting nanochannel advises the application of porous materials in water-related reactions via modulation of microenvironment.

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