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International Journal of Photoenergy
Volume 5, Issue 2, Pages 75-80
http://dx.doi.org/10.1155/S1110662X03000163

Effect of partial oxidation by ozonation on the photocatalytic degradation of humic acids

1Marmara University, Faculty of Engineering, Department of Environmental Engineering, Kadikoy, Istanbul 81040, Turkey
2Bogazici University, Institute of Environmental Sciences, Bebek, Istanbul 80815, Turkey

Copyright © 2003 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In this study humic acids, which are known to be a heterogeneous group of organic macromolecules found in natural waters, were oxidized using ozonation and photocatalysis in a sequential system. Ozonation was employed for achieving partial oxidation of humic acids prior to photocatalytic oxidation. Degradation of humic acid was explained by using pseudo first order reaction rate model based on UV-vis measurements. An improvement was achieved in the photocatalytic degradation rates with respect to the degree of pre-oxidation by ozonation. Due to the surface oriented nature of photocatalysis, adsorption characteristics of partially oxidized humic acid samples on TiO2 photocatalyst were evaluated by the application of the Freundlich adsorption model. The photocatalytic degradation rates did not correlate well with the dark adsorption characteristics of the pre-ozonated as well as untreated humic acid samples.