Investigation of Carbon Nanotubes in Mixed Matrix Membranes for Gas Separation: A Review

Mixed matrix membranes (MMM) consist of a polymeric base with additive fillers. Zeolites, carbon molecular sieves, graphene and carbon nanotubes (CNTs) are most commonly used fillers in the development of MMMs. Among these materials, CNTs have been proposed recently for gas separation application due to their attractive properties. Although CNTs have excellent separation properties, preparation of CNT-MMMs is more complicated. To employ CNTs as effective reinforcement in the polymeric matrix, proper dispersion and suitable interfacial adhesion between the CNTs and the polymer matrix have to be guaranteed. In this paper, recent advances and developments on CNTs dispersion and alignment in the matrix were reviewed. Also, a critical comparison of various CNT functionalization methods and different functional groups are given. Applications of CNT-MMMs in gas separation are also reviewed.