III International Conference

PP-III-54CATALYTIC BEHAVIOUR OF VARIOUS Fe/ZSM-5 ZEOLITES TOWARDS WETH 2 O 2 OXIDATION (CWPO) OF RHODAMINE G DYE IN AQUEOUS PHASESychev M.V., Stolyarova I.V., Goncharuk V.V.Dumanski Institute of Colloid and Water Chemistry, 03680, Kiev, UkraineE-mail: m.v.sychev@icccw.kiev.uaIt was demonstrated that catalytic activity of Fe/ZSM-5 zeolites in wet H 2 O 2 oxidation(CWPO) of Rhodamine G dye in aqueous medium depends on nature, location, dispersion ofiron species, as well as redox ability of iron forming those species. The impact of preparativeaspects on the catalytic properties of catalysts is discussed in details along with theircharacterizations by ICP, H 2 TPR, X-ray diffraction, in-situ FT-IR and electron microscopy.Fenton’s reagent (Fe 2+ /Fe 3+ /H 2 O 2 ) is one of the most common homogeneous oxidativecatalytic systems utilized for degradation of dyes. However, the need for removing theprecipitated catalyst significantly increases the overall costs. This drawback can be overcomeby application of heterogeneous catalysts such as iron-containing zeolites. It is generallyknown that the preparation method and further treatment has a profound influence on the ironspeciation and therefore may affect the final catalytic properties to a great extent. Here, wereport on our efforts to study the influence of such parameters on the performance towardsCWPO of Rhodamine G dye in water over Fe/ZSM-5 catalysts.Catalysts with different iron loading were prepared via conventional ion exchange (CE),improved aqueous ion exchange (IE) methods and by direct incorporation of Fe in thesilicalite framework during synthesis. For Fe/ZSM-5(IE), iron is predominantly present in theform of well-dispersed Fe 2+ ions, while Fe/ZSM-5(CE) and Fe-isomorphously substitutedmaterials contain mainly ferric ions as small oligonuclear (FeO) n clusters. The difference incatalytic behaviour in CWPO of the various catalysts is related to the different nature of theiron species. The catalyst activity strongly depends on the zeolite surface properties andcomposition, the dispersion of iron, the reaction temperature and parameters as pH and H 2 O 2addition rate. At 323 K, quasi-neutral pH (4.9), short contact time, a catalyst concentration of1.0 g.l -1 and a peroxide addition rate of 41.2 mmol h -1 , Fe/ZSM-5 prepared via the improvedprocedure and isomorphous substitution allow total degradation of the dye accompanied byremoval of 80% of TOC without notable leaching of Fe ions.573