Rapid Synthesis of Defect-Free Tubular Co-Gallate MOF Membranes for MeOH/MTBE Separation by Pervaporation

The Co-gallate MOF membrane exhibits great potential for separating MeOH/MTBE mixtures due to its regular pore size, exceptional stability, and high hydrophilicity. Nevertheless, the rapid nucleation and growth rate of the Co-gallate crystals in the synthesis solution cause poor nucleation on the substrate surface, which presents a significant challenge for the preparation of continuous Co-gallate membranes. In this study, we presented a cobalt carbonate hydroxide nanowire array (Co-NWA)-induced strategy that enabled the rapid and defect-free synthesis of tubular Co-gallate membranes within just 1 h. The presynthesized Co-NWAs on the substrate played as nucleation centers and anchoring sites, facilitating robust membrane formation. The effects of various synthesis parameters on the crystal morphology and membrane compactness were systematically examined. The optimized Co-gallate membrane demonstrated excellent pervaporation performance, with a permeation flux of 2.03 kg m^-2 h^-1 and a separation factor of 6711 for a 14.3/85.7 wt % MeOH/MTBE mixture, maintaining high performance for over 100 h, indicative of its remarkable long-term stability. This Co-NWA-induced synthesis strategy presents a promising approach for the industrial-scale application of Co-gallate MOF membranes and the design of other MOF membranes, thereby advancing their utility in requisite liquid separation processes.