A new photocatalytic reactor for trace contaminant control: a water polishing system.
In spacecraft water recovery systems there is a need to develop a postprocessor water polishing system to remove organic impurities to levels below 250 micrograms/L (ppb) with a minimum use of expendables. This article addresses the development of a photocatalytic process as a postprocessor water polishing system that is microgravity compatible, operates at room temperature, and requires only a minimal use of both oxygen gas (or air) and electrical power for low energy UV-A (315-400 nm) lamps. In the photocatalytic process, organic contaminants are degraded to benign end products on semiconductor surfaces, usually TiO2. Some challenging issues related to the use of TiO2 for the degradation of organic contaminants have been addressed. These include: i) efficient and stable catalytic material; ii) immobilization of the catalyst to produce a high surface area material that can be used in packed-bed reactors, iii) effective light penetration, iv) effective, microgravity-compatible, oxidant delivery; v) reduced pressure drop, and vi) minimum retention time. The research and development performed on this photocatalytic process is presented in detail. Grant numbers: NAS9-97182.
Gonzalez-Martin
A
A
Lynntech, Inc. College Station, TX 77840, USA.
Kim
J
J
Van Hyfte
J
J
Rutherford
L A
LA
Andrews
C
C
D002384:Catalysis; D018504:Ecological Systems, Closed; D005069:Evaluation Studies as Topic; D007477:Ions; D008021:Life Support Systems / Q000295:instrumentation*; D008027:Light; D009930:Organic Chemicals / Q000737:chemistry; D010777:Photochemistry; D013026:Space Flight / Q000295:instrumentation*; D018531:Spacecraft / Q000295:instrumentation; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*; D014893:Weightlessness
D007477:Ions; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium