6. Photochemical Processes

  1. Ian J. Tinsley

Published Online: 2 JUN 2004

DOI: 10.1002/047166717X.ch6

Chemical Concepts in Pollutant Behavior

Chemical Concepts in Pollutant Behavior

How to Cite

Tinsley, I. J. (2004) Photochemical Processes, in Chemical Concepts in Pollutant Behavior, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/047166717X.ch6

Author Information

  1. Oregon State University, USA

Publication History

  1. Published Online: 2 JUN 2004
  2. Published Print: 1 JUN 2004

ISBN Information

Print ISBN: 9780471095255

Online ISBN: 9780471667179



  • absorption spectra;
  • free radicals;
  • quantum yield;
  • solar irradiance;
  • photolysis rate constants;
  • hydroxyl radical;
  • ozone;
  • singlet oxygen;
  • nitrate radical;
  • oxidative reactions;
  • semi-conductor catalysis


Radiant energy can interact with organic compounds and induce chemical transformations both directly and indirectly. The objective is to predict which compounds would be susceptible, the rates at which transformations occur and products that may be produced. Direct photolysis depends on the ability of the compound to absorb (absorption spectrum) in relation to the available solar energy and the extent to which the absorbed energy can produce chemical change (quantum yield). Production of free radicals can result in significant reaction rates and complex reaction schemes. Indirect photolysis results from the generation of reactives oxidants, ozone, singlet oxygen and hydroxyl radical which in turn react with organic compounds in the atmosphere and aquatic environment. Characteristic reactions for each oxidant are defined and reaction rates calculated based on typical environmental concentrations of the oxidants. The environmental implication of semi-conductor photocatalysis is also discussed.