Designing a Reusable Ethylene Filter Cartridge for Plant Flight Hardware: Characterization of Thermally Desorbing Compounds

The chemical specificity of several adsorbents, capable of being recycled by thermal desorption, was determined using volatile organic compounds (VOCs) found in ISS cabin air. These VOC adsorbents will be used to design a reusable filter to control ethylene in plant growth chambers and other STS/ISS biological payloads. A reusable filter to remove plant-produced ethylene from plant growth chambers could help minimize the mass and power use of plant flight hardware. Spaceflight-rated plant growth chambers employ either passive or active catalytic scrubbers for maintaining acceptable levels of VOCs. Passive systems require consumables, while active systems require power and their performance can be degraded in high humidity environments. Each adsorbent was loaded with known amounts of VOCs at a known flow rate. The filtering capacity and chemical specificity of each compound was determined from measurements pre- and post-filter VOC concentration. Gas samples were analyzed in a gas chromatograph using an FID detector. The design of the filter consisted in determining the amount of each filter bed, such that a single cartridge can last for four days with a normal plant VOC load in a 30L, 0.25 m² chamber.