A review and future prospect of polymer blend mixed matrix membrane for CO2 separation

In recent years, carbon capture technology has received much attention to limit the adverse effect caused by rising carbon dioxide (CO2) concentration in the atmosphere. Membrane technology has risen as an attractive option for carbon capture as it is less energy-intensive and more environmentally friendly compared with adsorption, absorption, and cryogenic separation. Polymeric membranes dominate the gas separation industries as they are cheaper and easier to fabricate compared with inorganic membranes but are bound to the permeance-selectivity trade-off limitation. Recently, researchers have been modifying polymeric membrane by polymer blending and mixed matrix membranes (MMMs) to overcome the limitation. Polymer blending yields a polymer blend that combines the benefits of two or more polymeric material. Polyethylene glycol (PEG) and polyethersulfone (PES) are common polymeric materials used in the gas separation industry for membrane fabrication. PEG and PES were reviewed in this paper as potential polymer blends that efficiently separate CO2 due to their chemical characteristics. Another technique to overcome the trade-off limitation is fabricating MMMs that incorporate both polymeric membrane material and inorganic filler. However, MMM fabrication presents challenges such as polymer-filler incompatibility, void formation, and filler agglomeration due to unsuitable filler. Functionalized multi-walled carbon nanotubes (MWCNTs-F) were reviewed as fillers that are able to overcome the dispersion and polymer-compatibility issues and increase the gas separation performance of membranes. Hence, MMM that is fabricated from PEG, PES, and MWCNTs-F that combines both polymer blending and MMM techniques is believed to be a breakthrough for CO2/N-2 separation.