Table of Contents Author Guidelines Submit a Manuscript
International Journal of Photoenergy
Volume 5, Issue 2, Pages 107-114
http://dx.doi.org/10.1155/S1110662X03000217

Testing and performance of immobilized Fenton photoreactions via membranes, mats and modified copolymers

1Laboratory of Photonics and Interfaces, Department of Chemistry, Swiss Federal Institute of Technology, Lausanne 1015, Switzerland
2UMR 6503 CNRS, University of Poitiers, Poitiers 86022, France

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

During the last 6 years our laboratory has developed Fenton immobilized catalysts for the partial or total destruction of toxic organic compounds and their mixtures. This paper reports on Fe-supported noncorrosive supported membranes and fabrics like: Nafion, Nafion-glass mats and polyethylene block copolymers. These novel supported catalysts have shown acceptable kinetic rates, resistance to the leaching of Fe3+ into the solution and no corrosion to the highly oxidative radicals generated in the solution during Fenton immobilized photo-assisted catalysis. Nafion-Fe membranes degrade Orange II under visible light only up to pH 4.8. In the case of nafion glass mats supported Fe3+-ions, the initial pH could be raised up to 8 or above. The pH decreased to about 4 during the photodegradation of Orange II due to the formation of intermediate carboxylic acids but the costly initial acidification process necessary in the case of homogeneous Fenton processes is avoided. Carboxylates and carboxylic acids were observed by IR spectroscopy on the surface of the supported catalysts towards the end of the photodegradation process as well as carboxylic acids detected by HPLC. The IR bands are found at 1523 and 1557 cm-1 in the case of the copolymer-Fe3+ corresponding to two types of iron-carboxylate species. The formation of carboxylates explains the drop of pH during the photodegradation to values between 3 and 4 corresponding to the pKa of the carboxylic functional group.