Membrane-based air dehumidification: A comparative review on membrane contactors, separative membranes and adsorptive membranes

This review compares the different types of membrane processes for air dehumidification. Three main categories of membrane-based dehumidification are identified - membrane contactors using porous membranes with concentrated liquid desiccants, separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air, and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification. Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy, this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies. Essentially, the discussion is broken into three sections-one for each category-discriminating in terms of the driving force, membrane structure and properties, and its performance indicators. Readers will notice that despite having the same objective to dehumidify air, the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance. At the end of each section, a performance table or summary of dehumidifying membranes in its class is provided. The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification. (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

This review compares different types of membrane processes for air dehumidification, identifies three categories of membrane-based dehumidification, and analyzes their driving force, membrane structure, and performance indicators. The study reveals that different categories of membrane materials have different adaptability and performance in the dehumidification process. Finally, the overall performance of the three categories is summarized, and potential material innovations are discussed.