1 Improving photocatalyst performance for water purification through surface modifications Katherine, Amanda Mather, Dr. Paul Tratnyek August 20, 2010 Environmental and Biomolecular Systems Oregon Health & Science University Beaverton, OR USA

2 The Shield 500 Puralytics’ water purification device: “The Shield” Grant from ONAMI Source: The Oregonian

3 The Shield 500: How it works Glass mesh Titanium dioxide

4 The Shield 500: How it works

5 The Shield 500: How to Improve it

6 Surface modifications Surface modifications may: –Change the selectivity or yield of contaminants –Increase range of wavelength response –Increase efficiency by inhibiting recombination Surface modifications tested: –Platinum –Silver –Gold –Palladium

7 Experimental Procedures : Applying modification Ph otodeposition –40 mL vials –Piece of TiO 2 mesh (bare or previously modified) –Metal reagent solution of varying concentrations –Methanol as electron donor –Solar simulator for 20 min. –Wash and dry pieces while inside bottles

8 Experimental Procedures : Testing modification Modifications to be tested by : –Same 40 mL vials as deposition –Piece of TiO 2 mesh (bare or previously modified) –Caffeine as model contaminant –Degraded under solar simulator –UV-Vis absorbance used for analysis of degradation

9 Results : Caffeine Degradation

10 Results : Optimum Loading

11 Conclusions Platinum surface modification, while using H 2 PtCl 6 as a reagent solution, provides the largest improvement in photocatalyst performance and should be tested in The Shield 500 reactor.

12 Acknowledgements Thank you to Amanda Mather, Dr. Paul Tratnyek, CMOP, and Saturday Academy’s Apprenticeships in Science and Engineering.

13 Supplemental Slides

14 Experimental Procedures : Applying modification Gold deposited TiO 2 of various loadings

15 Caffeine

16 Solar Bag