Visible-Light-Responsive Photocatalysis: Ag-Doped TiO2 Catalyst Development and Reactor Design Testing
In recent years, the alteration of titanium dioxide to become visible-light-responsive (VLR) has been a major focus in the field of photocatalysis. Currently, bare titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Hg-vapor fluorescent light sources are used in photocatalytic oxidation (PCO) reactors to provide adequate levels of ultraviolet light for catalyst activation; these mercury-containing lamps, however, hinder the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. VLR-TiO2 would allow for use of ambient visible solar radiation or highly efficient visible wavelength LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Over the past three years, Kennedy Space Center has developed a VLR Ag-doped TiO2 catalyst with a band gap of 2.72 eV and promising photocatalytic activity. Catalyst immobilization techniques, including incorporation of the catalyst into a sorbent material, were examined. Extensive modeling of a reactor test bed mimicking air duct work with throughput similar to that seen on the International Space Station was completed to determine optimal reactor design. A bench-scale reactor with the novel catalyst and high-efficiency blue LEDs was challenged with several common volatile organic compounds (VOCs) found in ISS cabin air to evaluate the system’s ability to perform high-throughput trace contaminant removal. The ultimate goal for this testing was to determine if the unit would be useful pre-heat exchanger operations to lessen condensed VOCs in recovered water and lowering the burden of VOC removal for water purification systems.
University of Florida
ICES302: Physio-chemical Life Support- Air Revitalization Systems -Technology and Process Development
Janelle L. Coutts, Engineering Services Contract, Kennedy Space Center, USA
Paul E. Hintze, NASA Kennedy Space Center, USA
Anne Meier, NASA Kennedy Space Center, USA
Malay G. Shah, NASA Kennedy Space Center, USA
Jan M. Surma, Engineering Services Contract, Kennedy Space Center, USA
Robert W. DeVor, Engineering Services Contract, Kennedy Space Center, USA
Phillip R. Maloney, Engineering Services Contract, Kennedy Space Center, USA
Brint M. Bauer, Engineering Services Contract, Kennedy Space Center, USA
David W. Mazyck, University of Florida, USA
The 46th International Conference on Environmental Systems was held in Vienna, Austria, USA on 10 July 2016 through 14 July 2016.