Exploration of the Synergy Between 2D Nanosheets and a Non-2D Filler in Mixed Matrix Membranes for Gas Separation

Feng Shi; Junxia Sun; Jingtao Wang; Min Liu; Shaofei Wang; Xingzhong Cao; Zhikun Yan; Yifan Li; Suzana P Nunes

doi:10.3389/fchem.2020.00058

Exploration of the Synergy Between 2D Nanosheets and a Non-2D Filler in Mixed Matrix Membranes for Gas Separation

Front Chem. 2020 Feb 5:8:58. doi: 10.3389/fchem.2020.00058. eCollection 2020.

Authors

Feng Shi¹, Junxia Sun¹, Jingtao Wang¹, Min Liu¹, Shaofei Wang², Xingzhong Cao³, Zhikun Yan¹, Yifan Li¹, Suzana P Nunes²

Affiliations

¹ Department of Chemical Engineering, Zhengzhou University, Zhengzhou, China.
² Biological and Environmental Science and Engineering Division, Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
³ Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.

Abstract

Dual-filler MMMs have attracted special interests in recent years because of the possibility of producing synergetic effect. This study is aimed at exploring the underlying synergy between two-dimensional (2D) nanosheets and a non-2D filler in mixed matrix membranes for gas separation. MXene or graphene oxide (GO) as typical nanosheet filler is selected to be in pair with a non-2D filler, SiO₂ or halloysite nanotubes (HNTs), with Pebax as the polymer matrix. In this way, four pairs of binary fillers are designed and the corresponding four groups of MMMs are fabricated. By tuning the mass ratio of binary fillers, synergetic effect is found for each group of MMMs. However, the two 2D fillers found different preferential non-2D partners. GO works better with HNTs than SiO₂, while MXene prefers SiO₂ to HNTs. To be noted, GO/HNTs renders the membranes the maximum enhancement of CO₂ permeability (153%) and CO₂/N₂ selectivity (72%) compared to Pebax control membrane, while each of them as single filler only brought about very limited enhancement of CO₂ separation performance. The possible mechanisms are thoroughly discussed in terms of filler dispersion, nanosheet flexibility, and the tortuosity and connectivity of the surface diffusion pathways along nanosheets.

Keywords: GO; HNTs; MXene; Pebax; SiO2; mixed matrix membrane.