Preparation of 2D lamellar CD-MOF membranes for accurate separation of mixed solvents

With the rapid development of membrane technology in the field of separation, membrane technology has received extensive attention in the application of replacing traditional high-energy distillation in mixed solvent separation. However, preparing separation membranes with uniform subnanometer pore remains a tough challenge. In this paper, isotropic cyclodextrin metal-organic framework (CD-MOF) cubic particles were induced by benzoic acid to generate splintered structure, and then the two-dimensional CD-MOF nanosheets were prepared by liquid phase ultrasonic stripping method, which were further used as building units to assemble lamellar MOF membrane. Importantly, CD-MOF nanosheets contain abundant, connected and homogeneous intrinsic subnanometer pores (0.78 nm), which can recognize the tiny size differences between molecules to achieve accurate separation of mixed solvents. For instance, the separation factor of lamellar CD-MOF membrane for the mixed solvent of 1, 3, 5-triisopropylbenzene and diisopropylbenzene dissolved in benzene (molar ratio of 1∶3) is up to 7.4. In addition, the rejection of methyl orange dye (1.0 nm) dissolved in methanol reaches 99.6%, and the methanol permeance reaches 84.3 L·m-2·h-1·bar-1. © 2022 Chemical Industry Press. All rights reserved.