Advancing O₂/N₂ separation with thin film coatings on hollow fiber membranes: A review

There is an ever-increasing need for separation technologies to efficiently use oxygen and nitrogen from air, driven by advancements in industrial applications such as petrochemistry, electronics, agriculture and aviation. Membrane-based air separation is one of the fastest growing technologies due to its unique advantages in terms of compactness, cost and energy effectiveness. However, this technology, which is mature with existing polymeric hollow fiber membrane materials, has obstacles to the industrial scale application of new generation high permeance polymers. Existing gas separation membranes need to be further improved in terms of permeability and selectivity to expand the market share and compete with traditional separation technologies. This article provides a comprehensive overview of air separation regarding the elimination of existing obstacles. Then, thin film coating strategies and materials followed in the fabrication and structural development of hollow fiber membranes for air separation are discussed. Polymeric properties affecting oxygen and nitrogen in air separation are investigated. Finally, the role of composite materials in oxygen transport in thin film coatings and elimination of existing obstacles and future research directions are evaluated. Consequently, this review aims to serve as a compilation for advancing membrane technology towards more sustainable and efficient air separation solutions.