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  Home > JCE Print > Journal of Chemical Education > Issues > 1998  > June  >
In the Classroom
Tested Demonstrations
Photocatalytic Degradation of a Gaseous Organic Pollutant
Jimmy C. Yu and Linda Y. L. Chan
The Chinese University of Hong Kong, Department of Chemistry, Shatin, N.T., HONG KONG

Cover
June 1998
Vol. 75 No. 6
p. 750

Abstract
A simple and effective method to demonstrate the phenomenon of photocatalytic degradation of a gaseous organic pollutant was developed. Titanium dioxide (anatase) was used as the photocatalyst, and sunlight was found to be an effective light source for the activation of TiO2. The organic pollutant degrade in this demonstration was a common indoor air pollutant, dichloromethane. The TiO2 powder was suspended in a 3:7 ethanol/water solution, and then coated on microscopic slides. The slides together with appropriate indicators were place in 250-mL conical flasks. A small amount of the volatile dichloromethane solvent was injected into each flask, and the flasks were sealed with a piece of parafilm. Some of the flasks were exposed to direct sunlight, and some were kept in the dark. The degradation products of dichloromethane were carbon dioxide, water, and hydrogen chloride. Formation of the acidic HCl gas could be monitored easily by two indicators, the universal pH paper and ammonia. The universal pH paper would change color from green to red in the presence of HCl and H2O, while HCl would react with ammonia to form a white fume. The results of this demonstration showed that both TiO2 and light were required in this photocatalytic degradation process.
More Information
*  Citation
Yu, Jimmy C.; Chan, Linda Y. L. J. Chem. Educ. 1998 75 750.
*  Keywords
Demonstrations, Catalysis, Photochemistry, Teaching/Learning Aids
*  History
Created:
Last Updated:
June 23, 1999
June 24, 2005
  Home > JCE Print > Journal of Chemical Education > Issues > 1998 > June > Page 750


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