Abstract:

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.

Key words: cyclodextrin metal-organic framework, 2D lamellar membrane, size sieving, nanofiltration, selectivity, separation

摘要：

随着膜分离技术的迅速发展，其应用于混合溶剂分离以替代传统高能耗精馏等操作受到了越来越多研究者的关注，但制备具有均匀亚纳米筛分孔的分离膜是其面临的挑战。利用苯甲酸诱导各向同性的环糊精金属有机框架（CD-MOF）三维立方颗粒产生错层结构，再通过液相超声剥离法制得CD-MOF纳米片，以此为构筑单元制备二维层状MOF膜。膜内CD-MOF纳米片含有丰富、连通且均匀的本征亚纳米孔（0.78 nm），可识别分子间微小的尺寸差异，实现混合溶剂精准分离。如CD-MOF层状膜对溶解在苯中的均三异丙基苯与二异丙基苯混合液（摩尔比为1∶3）的分离因子达到7.4。此外，膜对溶解在甲醇中的甲基橙染料（1.0 nm）截留率达到99.6%，且甲醇通量达84.3 L·m^-2·h^-1·bar^-1。

关键词: 环糊精金属有机框架, 二维层状膜, 尺寸筛分, 纳滤, 选择性, 分离