• 文献标题:   Experimental and theoretical exploration of gas permeation mechanism through 2D graphene (not graphene oxides) membranes
  • 文献类型:   Article
  • 作  者:   NEZHAD FA, HAN N, SHEN ZF, JIN Y, WANG YG, YANG NT, LIU SM
  • 作者关键词:   gas separation, graphene oxide membrane, graphene membrane, 2d membrane
  • 出版物名称:   JOURNAL OF MEMBRANE SCIENCE
  • ISSN:   0376-7388 EI 1873-3123
  • 通讯作者地址:   Curtin Univ
  • 被引频次:   4
  • DOI:   10.1016/j.memsci.2020.117883
  • 出版年:   2020

▎ 摘  要

Exploration of novel molecular sieving membranes with improved performance and reduced synthesis cost is always a hot topic with one typical example of recently emerged 2D graphene oxides (GO) membranes. These graphene oxide (GO) nanoflakes with thickness less than 10 nm have been applied as the building block to assemble these 2D membranes. Most of these multi-layered GO nanosheets themselves have inherent interlayer channels. To clarify the molecular sieving property stemmed from the interspace of the building block itself or between two neighboring blocks, in this work, commercial graphene flakes (GF) with average thickness of 7 nm were applied to form GF membranes under the hydraulic pressure. GF membrane in the overall thickness of 0.75 mm made from 25-mu m-sized flakes displayed good molecular sieving property and the measured helium permeance of 2.02 x 10(-8) mol s(-1) m(-2) Pa-1 with selectivity of 65 (He/CO2) and 22 (He/N-2) and separation factor more than 10 from gas mixture separation. Such results clearly demonstrate that molecular sieving properties are sourced from the tortuous interspace between the building blocks as the individual GFs are gas impermeable. Modeling results indicate that two main types of pores (larger size from 2 to 4 nm for Knudsen diffusion and smaller size from 0.3 to 0.4 nm for molecular sieving) co-exist in such membranes. Modeling results also imply that despite of the large overall thickness (0.75 mm), the molecular sieving layer inside the GF membrane was only 247 nm contributing the gas selectivity. The effect of graphene flake size on gas permeation behavior on the resultant membrane was also investigated. This work may provide some insights to the mass transport mechanism of these 2D graphene membranes.