The catalytic and photocatalytic oxidation of organic substances using heterogeneous Fenton-type catalyst E.V.Kuznetsova*, E.N.Savinov*, L.A.Vostrikova**, G.V.Echevskii** * Group of photocatalysis on semiconductors, Boreskov Institute of Catalysis, Pr.Ak.Lavrentieva, Novosibirsk 630090, Russia (E-mail: ekaterina@catalysis.nsk.su) ** Laboratory of catalytic conversion of hydrocarbons, Boreskov Institute of Catalysis, Pr.Ak.Lavrentieva, Novosibirsk 630090, Russia Abstract This paper is dealing with catalytic and photocatalytic oxidation of organic substances using H 2 O 2 over heterogeneous Fenton-type catalysts. In the study a series of Fe- containing catalysts was experienced. A zeolite named as FeZSM-5 was selected as the most active heterogeneous Fenton-type catalyst. The FeZSM-5 reported was prepared by the hydrothermal crystallization in the presence of iron salt. In contrast to homogeneous Fenton system the catalyst prepared had minimal if any leaching of iron ions, was stable during thirty catalytic runs and didn’t lose its activity in a presence of complexing agents, e.g. P 2 O 7 4- . The catalyst was active in oxidation of organic substances at pH from 1.5 to 8, maximum activity was observed at pH=3. The FeZSM-5 effectively oxidized a simulant of warfare agent, diethylnitrophenil phosphate, which is hardly detoxified by other methods. It appeared that the rate of oxidation of formic acid, ethanol and benzene over FeZSM-5 increased under the action of visible light (λ>436 nm), quantum efficiency being 0.06- 0.14. Keywords Fenton-type catalysts, Fe-containing zeolites, oxidation, organics, photocatalysis, visible light INTRODUCTION The Fenton and photo-Fenton processes are known as effective and inexpensive methods for water and wastewater purification from organic pollutants (Ruppert, 1993; Schulte, 1994; Prousek, 1995). Hydrogen peroxide as an oxidant doesn’t produce toxic by-products and together with aqueous iron salts oxidizes organic substances in mild conditions. However such drawbacks as solution contamination by transition metal ions, the limited pH range, deactivation of homogeneous catalysts by complexing agents, e.g. phosphates, necessitate researchers to develop new catalysts active in the Fenton-type mechanism. As a result Fe-containing solid catalysts, such as zeolites, were found to possess activity in oxidation of organic substances (Pulgarin et al., 1995). Moreover stable heterogeneous catalysts with minimal leaching of iron ions were developed and successfully experienced in oxidation of phenol (Fajerwerg et al., 1996) and carboxylic acids (Centi, 1999; Centi et al., 2000). In date iron introducing into zeolites is carried out by two different methods: ion exchange starting from already crystalline zeolite (Pulgarin et al., 1995; Centi et al., 2000) or joint crystallization during hydrothermal treatment (Fajerwerg et al., 1996). Activity of Fe-zeolite, prepared by the first method, has been studied in more detail. This work presents detailed analysis of stability and oxidative activity of the Fe-containing zeolite, prepared by the hydrothermal method (Vostrikova, 1981; Ione, 1987). The other aspect of this paper is the influence of light on the system. It is well known that UV (λ>250 nm) light irradiation improves the effectiveness of the homogeneous Fenton system due to the regeneration of the consumed Fe 2+ ions and direct H 2 O 2 photolysis (Ruppert, 1993). Papers (Pignatello, 1992) and (Sun, 1993) show that under the near UV light (λ=300-400 nm) some other