Space-confined growth of 2D MOF sheets between GO layers at room temperature for superior PDMS membrane-based ester/water separation

Expanding the metal-organic frameworks (MOFs) category using room-temperature colloidal chemistry route with regular crystal structure is challenging, but important for reducing energy consumption and realizing an economically viable application in industry. Herein, we developed a novel advanced copper terephthalate MOF (CuBDC) between graphene oxide (GO) layers using a simple space-confined growth strategy at room temperature. The inclusion of CuBDC@GO can realize high filler loadings while maintaining uniform dispersion throughout PDMS matrix. The paralled arranged CuBDC sheets created 1D inner vertical channels, along with the enlarged GO interlayer space for rapid molecule permeselective transport. The resultant mixed matrix membranes (MMMs) with 30 wt% CuBDC@GO loading improved the separation factor from 190.6 to 576.3, and simultaneously increased the total flux from 575.2 to 1357.4 g m-2 h-1 for separating 0.5 wt% butyl acetate at 40 degrees C. The transport mechanism was explained by adjusting the CuBDC content in composites to examine the significant increase in membrane permeability (from 12.5 to 58.3) and selectivity (from 0.7 to 2.0). Compared to alcohol or ketone, the larger size strip-like butyl acetate molecules are ideal for rapid transport through the CuBDC-supported 1D continuous inner channels, and effectively inhibit the movement of water molecules, ultimately resulting in the largest pervaporation performance improvement in butyl acetate/water separation. This CuBDC@GO prepared by a simple, green and room-temperature synthesis route can be widely applied to prepare defect-free membranes with excellent performance for sustainable applications. We also anticipate that this advanced space-confined growth strategy can be extended to various other MOFs and applications.

Automated summary

Expanding the metal-organic frameworks (MOFs) category using room-temperature colloidal chemistry route with regular crystal structure is challenging, but important for reducing energy consumption and realizing an economically viable application in industry. In this study, the researchers developed a novel advanced copper terephthalate MOF (CuBDC) between graphene oxide (GO) layers using a simple space-confined growth strategy at room temperature. The inclusion of CuBDC@GO allowed for high filler loadings while maintaining uniform dispersion throughout PDMS matrix, and the parallel arranged CuBDC sheets created 1D inner vertical channels, along with the enlarged GO interlayer space for rapid molecule permeselective transport.