Actions for Photooxidation of organic wastes using semiconductor nanoclusters. 1998 annual progress report [electronic resource].

Email RIS file
Bookmark
Report an Issue

Photooxidation of organic wastes using semiconductor nanoclusters. 1998 annual progress report [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy. Office of Environmental Management, 1998.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
4 pages : digital, PDF file
Additional Creators
Sandia National Laboratories, United States. Department of Energy. Office of Environmental Management, and United States. Department of Energy. Office of Scientific and Technical Information
Access Online

Availability

I Want It
I Want It

Finding items...

Restrictions on Access
Free-to-read Unrestricted online access
Summary
'This report summarizes work after 1.5 years of a 3-year project. The authors efforts have focused on demonstration of photocatalysis of organic pollutants using nanosize MoS₂. They investigated the effects of (1) bandgap, valence and conduction band energies; (2) surface modification of MoS₂ by deposition of metal and metal oxide islands to enhance electron transfer; and (3) use of semi-conductor semi-conductor composites to achieve improved charge separation and thus photooxidation of pollutants. They synthesized and studied nanosize MoS₂ of three different sizes and associated bandgaps and studied photoredox reactions of nanosize MoS₂ dispersed in solution and supported on a macroscopic powder. The latter would be the method of choice for use as a practical photocatalyst for water purification. As they emphasized in the original proposal, MoS₂ in nanosize form can be tuned to absorb various amounts of the solar spectrum. They discovered there is an optimal choice of absorbance characteristics and valence and conduction band levels which allow the rapid photo-oxidation of a chosen organic molecule. The advantages of having a photostable material with a tunable bandgap were demonstrated in an experiment where phenol destruction with visible (> 450 nm) light occurred at a dramatically faster rate with nanoscale MoS₂ catalysts compared to the best available previous material TiO₂. This was the first demonstration of rapid photooxidation of an organic molecule using a completely photostable catalyst and only visible light. The possibility of transferring electrons or holes between nanoscale MoS₂ and other semiconductor materials in order to increase electron/hole lifetimes were explored. It was shown that small amounts (<5 weight %) of nanoscale MoS₂ deposited on to TiO₂ can lead to significant (∼2) enhancements of phenol destruction rates. A number of different chemicals were photocatalyzed sucessfully to CO₂, but most of the work centered on the destruction of phenol. This particular organic was chosen for its ease of detection and relative resistance to oxidation, and because its photo-oxidation has been studied extensively by many previous researchers. No attempts were made to find the absolute quantum yield of the photo-oxidation process. Rather, following the approach of Serpone and coworkers they compared the relative activity of nanoscale MoS₂ to a well studied photocatalyst, Degussa P25 TiO₂. Chemical analysis was done with high pressure liquid chromatography (HPLC) using a reverse phase column, Hewlett-Packard 1050 diode array detector, and Hewlett-Packard 1046A fluorescence detector. The fluorescence detector allowed detection of phenol to ∼ 10 ppb without preconcentration. They were typically able to destroy phenol and certain cholorinated hydrocarbons such as pentachlorophenol (a common wood preservative) to undetectable levels in less than 2--3 hours of treatment.'
Report Numbers
E 1.99:emsp-55387--98
emsp-55387--98
Other Subject(s)
Note
Published through SciTech Connect.
06/01/1998.
"emsp-55387--98"
"DE00013680"
Wilcoxon, J.P.
Type of Report and Period Covered Note
Annual; 12/31/1997 - 12/31/1998
View MARC record | catkey: 14142344