Thin film nanocomposite embedded with polymethyl methacrylate modified multi-walled carbon nanotubes for CO2 removal

Abstract

Over the past decades, carbon nanotubes (CNTs) have gained tremendous attention as nanofillers in nanocomposite membranes owing to their potential to improve the physical properties and gas separation performance. In this work, polyamide-ethylene oxide (PA-EO) thin film nanocomposite (TFN) membranes embedded with polymethyl methacrylate (PMMA) grafted multi-walled carbon nanotubes (MWNTs) were successfully fabricated. The TFNs were fabricated via an interfacial polymerization (IP) technique to allow the formation of a very thin selective skin. The effects of the incorporation of nanofiller within the coating and selective thin film layers on the membrane morphologies and gas separation performance have been highlighted. The TFN incorporating milled PMMA-MWNTs within its coating layer showed a 29% increment in CO2 permeance (70.5 gas permeation units (GPU)) with 47% and 9% enhancement in CO2/N2 and CO2/CH4 selectivity respectively compared to its thin film composite counterpart. While the improvement in gas separation performance can be primarily attributed to the presence of highly diffusive channels rendered by the CNTs, PMMA grafting is also believed to play an important role to ensure good nanofiller dispersion and good filler-polymer compatibility. Uncovering the construction of membrane fabrication could pave facile yet versatile ways for the development of effective membranes for greenhouse gas removal.