Space life-supporting systems require effective removal of metabolic CO2 from the cabin atmosphere with minimal loss of O2. Conventional techniques, using either metal hydroxide or metal oxide sobent, require after-mission regeneration or replacement, thus putting a critical cap on mission duration. More recent techniques, such as pressure swing adsorption-based process also require regeneration and use expendable resources. A novel approach to the problem is the use of a membrane device that can effectively separate CO2 in the presence of moisture, using space vacuum as the driving force. Such a membrane device has minimal mass, volume and power penalty and does not require regeneration; therefore, long-duration space exploration can be realized. In Phase I, we will develop a novel nanocomposite membrane with a microporous aminosilicate structure for enhanced CO2 separation with simultaneous humidity control. CO2 preferentially adsorbs onto the pore surfaces of the aminosilicate membrane and transports via surface diffusion, thus resulting in pore blockage or pore size reduction to prevent other inert gases such as O2 and N2 from permeating through. With the combination of molecular sieving and surface diffusion mechanisms, the proposed membrane can be expected to achieve superb CO2 separation performance for effective spacecraft cabin air revitalization.
