Building extra transport channels in mixed-matrix membrane for air dehumidification

Membrane separation is a promising technology relative to the mature distillation technique due to its high energy efficiency. Incorporating nanoparticle to polymer matrix to fabricate mixed-matrix membranes (MMMs) is one of effective ways to overcome the typical trade-off relationship between gas permeability and selectivity. Although silica based MMMs were studied for natural gas dehydration and desalination, it is rarely been investigated for air dehumidification. Herein, membrane material with high water vapor affinity of Pebax 1074 was applied as polymer matrix and silica was incorporated as filler to fabricate MMMs. The embedded silica filler can simultaneously enhance water vapor permeability (13–33% up) and H₂O/N₂ selectivity (40–60% up) at an optimal loading of 1 wt%. The relatively hydrophobic form improved water vapor permeability due to the pronounced enlarged d-spacing and the resultantly enhanced diffusivity coefficient. The more hydrophilic filler enhanced more H₂O/N₂ selectivity than that of the counterpart because of the largely improved water vapor solubility coefficient. The concomitant improvement of both water vapor permeability and its selectivity makes it stand out from the various previously reported membranes, demonstrating its potential for scale-up application.