Preliminary study on ZIF-8 containing hollow fiber mixed matrix membranes (HFMMMs) for CO2 and CH4 gas permeation

Abstract

The advantages in terms of smaller footprint, higher energy efficiency, larger surface-to-volume ratio and higher flux have opened various opportunities for hollow fiber membranes in separation processes especially in carbon dioxide (CO2) capture. Although the development of polymeric hollow fiber membrane has emerged as an important material in membrane technology, currently existing polymeric materials suffer from a limiting trade-off between selectivity and permeability. Recently, it has been reported in the literature that the addition of metal–organic frameworks into polymer matrixes have radically improved the separation performance of CO2 from methane (CH4), as well as enhanced the thermal stability and structural properties of the membrane. In this preliminary study, ZIF-8/cellulose triacetate hollow fiber mixed matrix membranes are fabricated by varying the air gap distances and subsequently, the morphology of the resultant membranes was analysed using a scanning electron microscope while the dispersion of ZIF-8 fillers in the polymer matrix was observed using an energy dispersive X-ray. The results showed that the ZIF-8 fillers were homogeneously distributed into the cellulose triacetate polymer. Then, the performance of the resultant membranes before and after post-treatment with polydimethylsiloxane in CO2 and CH4 gases permeation were evaluated. Due to the presence of multiple defects, the overall performance of the fabricated membranes was low with no significant improvements after post-treatment. Hence, further optimization study on the fabrication process is still required to improve the performance of the ZIF-8/cellulose triacetate hollow fiber mixed matrix membrane in CO2 and CH4 gas permeation.