Indexed by:Journal Article

Date of Publication:2019-05-01

Journal:SEPARATION AND PURIFICATION TECHNOLOGY

Included Journals:EI、CPCI-S、SCIE

Volume:214

Issue:,SI

Page Number:87-94

ISSN:1383-5866

Key Words:Gas separation; Mixed matrix membranes; Grapheneoxide; Zeolitic imidazolate frameworks; CO2 capture

Abstract:Graphene oxide (GO) has been employed as filler in mixed matrix membranes (MMMs) to enhance gas selectivity as its high-aspect ratio structure makes the path of gas diffusion longer and tortuous, improving diffusivity selectivity of gases with different molecular sizes. However, the stacking and folding structure of GO nano-sheets leads to gas barrier effects which reduce gas permeability. In this paper, a strategy of modifying continuous ZIF-8 layer with ultra-microporosity and high gas permeability on the surface of GO nano-sheets was proposed to increase the size and connectivity of gas transfer passage. ZIF-8@GO nano-sheets were successfully prepared by two-step ultrasonic synthesis method of growing ZIF-8 on GO surface at room temperature and the flexibility of nano-sheets could be easily tuned by different reaction times. CO2 permeability of ethyl cellulose (EC)/ZIF-8@GO MMMs achieves continuous enhancement with the increased loading of ZIF-8@GO compared with pure GO based MMMs which shows rare effective improvement in CO2 permeability. EC/ZIF-8@GO membrane containing 20 wt% fillers exhibits CO2 permeability of 203.3 Barrer together with CO2/N-2 selectivity of 33.4, increased by 139% and 65% from that of pristine EC membrane respectively, and this performance is also higher than that of MMMs containing independent GO or ZIF-8. Having distinct improvement of CO2 separation performance, the modification strategy using ultra-porosity MOFs to enhance gas transfer of 2D nano-sheets is promising for fabrication of high performance CO2 separation membranes.