Browsing by Author "Wilburn, Monique S."
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Item Adsorption of Ammonia on Regenerable Carbon Sorbents(45th International Conference on Environmental Systems, 2015-07-12) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Wilburn, Monique S.Results are presented on the development of reversible sorbents for the combined carbon dioxide, moisture, and trace-contaminant (TC) removal for use in extravehicular activities, and more specifically in the Primary Life Support System. The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Data on sorption and desorption of ammonia, which is a major TC of concern, are presented in this paper. The current TC-control technology involves the use of a packed bed of acid- impregnated granular charcoal, which is non-regenerable. The carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. In this study, several carbon sorbents were fabricated and tested for ammonia sorption. Ammonia-sorption capacity was related to carbon pore structure characteristics, and the temperature of oxidative carbon-surface treatment was optimized for enhanced ammonia- sorption performance.Item Co-Adsorption of Ammonia and Formaldehyde on Regenerable Carbon Sorbents for the Primary Life Support System (PLSS)(46th International Conference on Environmental Systems, 2016-07-10) Wojtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Wilburn, Monique S.Results are presented on the development of a reversible carbon sorbent for trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is deemed non-regenerable, while the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. Data on concurrent sorption and desorption of ammonia and formaldehyde, which are major TCs of concern, are presented in this paper. A carbon sorbent was fabricated by dry impregnation of a reticulated carbon-foam support with polyvinylidene chloride, followed by carbonization and thermal oxidation in air. Sorbent performance was tested for ammonia and formaldehyde sorption and vacuum regeneration, with and without water present in the gas stream. It was found that humidity in the gas phase enhanced ammonia-sorption capacity by a factor larger than two. Co-adsorption of ammonia and formaldehyde in the presence of water resulted in strong formaldehyde sorption (to the point that it was difficult to saturate the sorbent on the time scales used in this study). In the absence of humidity, adsorption of formaldehyde on the carbon surface was found to impair ammonia sorption in subsequent runs; in the presence of water, however, both ammonia and formaldehyde could be efficiently removed from the gas phase by the sorbent. The efficiency of vacuum regeneration could be enhanced by gentle heating to temperatures below 60 °C.Item Development of Trace Contaminant Control Prototypes for the Portable Life Support System (PLSS)(47th International Conference on Environmental Systems, 2017-07-16) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Nalette, Tim; Guerrero, Sandra V.; Papale, William; Wilburn, Monique S.Results will be presented on the development of a reversible carbon sorbent for trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. Data on sorption and desorption of ammonia and formaldehyde, which are major TCs of concern, as well as pressure-drop calculations were used to design and test 1/6-scale and full-scale trace contaminant control system (TCCS) prototypes. Carbon sorbents were fabricated in both the granular and foam-supported forms. Sorbent performance was tested for ammonia sorption and vacuum regeneration in 1/6-scale, and pressure-drop characteristics were measured at flow rates relevant to the PLSS application.