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Feasibility of the use of microwave heating to achieve fast and efficient thermal regeneration of sorbents for the removal of carbon dioxide, water vapor, and trace organics from contaminated air streams has been conclusively demonstrated. The use of microwave power offers several advantages, including: improved heat transfer, lower thermal losses, improved power utilization, and enhanced operational capabilities. During the initial research, the sorption and microwave-powered thermal desorption of acetone, trichloroethylene (TCE), carbon dioxide, and water vapor was studied at 2.45 GHz using a rectangular waveguide based test apparatus. Both activated carbon and Carbosieve S-III were identified as excellent microwave regenerable sorbents for use in the removal of airborne organics. Water loaded silica gel, Molecular Sieve 13X, and Molecular Sieve 5A were also effectively regenerated under microwave irradiation at this frequency.

Small, highly polar organics such as urea, alcohols, acetone, and glycols are not easily removed by the International Space Station's Water Recovery System. The current design utilizes the Volatile Removal Assembly (VRA) which operates at 125°C to catalytically oxidize these contaminants. Since decomposition of these organics under milder conditions would be beneficial, several ambient temperature biocatalytic and catalytic processes were evaluated in our laboratory. Enzymatic oxidation and ambient temperature heterogeneous catalytic oxidation of these contaminants were explored. Oxidation of alcohols proceeded rapidly using alcohol oxidase; however, effective enzymes to degrade other contaminants except urea were not found. Importantly, both alcohols and glycols were efficiently oxidized at ambient temperature using a highly active, bimetallic noble metal catalyst.

Novel mesoporous bimetallic oxidation catalysts are described, which are currently under development for the deep oxidation (mineralization) of aqueous organic contaminants in wastewater produced on-board manned spacecraft, and lunar and planetary habitats. The goal of the ongoing development program is to produce catalysts capable of organic contaminant mineralization near ambient temperature. Such a development will significantly reduce Equivalent System Mass (ESM) for the ISS Water Processor Assembly (WPA), which must operate at 135°C to convert organic carbon to CO2 and carboxylic acids. Improvements in catalyst performance were achieved due to the unique structural characteristics of mesoporous materials, which include a three-dimensional network of partially ordered interconnected mesopores (5-25 nm).