Graphene oxide based nanocomposite membrane for efficient CO2 separation

Graphene oxide (GO) is a one-atom-thick two dimensional material which has unique mechanical, electrical and structural properties. Recently, the attempt to apply GO in gas separation membranes has attracted increasing attention due to the molecular sieving effect of the controlled GO defects and its potential to form high efficient gas flow channels. However, most current works focus on the flat sheet GO membrane prepared via filtration or blending, and performance of the GO nanocomposite hollow fibre membranes still remain poorly understood. In this study, a series of hollow fibre gas separation membranes were prepared with GO and PEBAX® as the selective layer via a dip coating method on commercial PVDF microfiltration membrane surface. Prior to the GO/PEBAX coating, the support membrane was initially coated with a layer of PTMSP in order to minimize the penetration of the GO/PEBAX into the membrane pores. The gas separation results under room temperature revealed the GO content had significant effect on the membrane performance. With the increase of GO content in the PEBAX layer, the CO2 permeance of the composite membrane firstly decreased then increased. GO nanosheets are impermeable to gases, thus the presence of GO layer inside the PEBAX would increase the membrane resistance. On the other hand, the confined laminar structure also hindered the crystallization of PEBAX, which led to higher free volume near the polymer-GO interface, which provided high efficient gas transport channels and resulted in higher permeance. The optimized GO/PEBAX nanocomposite membrane could improve the membrane permeance by 50 % while remain the selectivity unchanged when compared with pure PEBAX benchmar