Preparation of MoS2@ZIF-8 membrane by supercritical CO2 method for efficient nanofiltration

Two-dimensional layered material membranes show great potential in the efficient sieving of molecules. However, balancing permeability and selectivity remains a significant challenge. In this study, ZIF-8 crystals are in situ grown on molybdenum disulfide (MoS 2 ) nanosheets exfoliated via supercritical carbon dioxide (scCO 2 ) for the first time, aiming to fabricate high-permeability MoS 2 @ZIF-8 membranes. It is suggested that the dispersed ZIF-8 crystals act as spacers to alleviate the restacking of MoS 2 nanosheets. The intrinsic microporous structure of ZIF-8, together with the tortuous transport pathways within the stacked MoS 2 layer, synergistically contributes to the size-selective separation performance of the membrane. Dye rejection tests show that the MoS 2 @ZIF-8 membrane exhibits high rejection rates and water permeability for various dye molecules. For example, the membrane has a rejection rate of 99.37% and a water permeability of 76.96 L m −2  h −1 ·bar −1 for Congo Red, and maintains an average rejection rate of 99.30% over 24 h of continuous operation. Moreover, the membrane can efficiently remove various dyes from salt-containing wastewater, with a maximum separation factor (SF) of 179.45 with a permeability of 79.77 L m −2  h −1 ·bar −1 . This method provides a promising solution for treating and purifying wastewater using membrane separation technology.