Graphene - based membranes for carbon dioxide separation

A significant portion of the global energy is nowadays dedicated to separation and purification processes, most of which exhibit limited efficiency mainly due to thermodynamic limitations. As an alternative, membrane-based technologies show increasing potential due to the fact that membranes can combine selective separation at the molecular level, energy-efficient operation, and cost effectiveness. Membranes can be applied in various fields that involve liquid and gas separation such as water desalination and treatment, air purification, gas sweetening, and carbon dioxide capture/separation. Ability to develop a variety of membranes, establish new synthesis approaches, involve suitable materials and composites, and thoroughly study the resulting membrane characteristics with holistic experimental and theoretical toolsets are critical toward enhancing performance efficiency and enabling scalability. Membrane application in liquid mixture separations, such as desalination and water treatment, is well integrated into the industrial practice, yet in separation of gases and particularly mixtures involving CO2, there is still a long way to go until significant industrial integration is implemented. Lately, the fascinating graphene has been evolved into fabrication of CO2 separation membranes often exhibiting superior performance and fundamentally interesting gas transport phenomena from macroscopic to molecular scale. This work aims to showcase and critically review up to date advances in graphene-based membranes for CO2 separation, by visiting synthesis approaches, separation and gas transport mechanisms, and membrane types including inorganic, hollow fiber and mixed matrix ones. The review intends to be a useful reference for those investigating CO2 separation using membrane technologies targeting capture from various emission sources and purification before conversion/utilization.