02608naa a2200229 a 450000100080000000500110000800800410001910000200006024500950008026000090017550000290018452018000021365000130201365300200202665300150204665300210206165300150208270000210209770000200211870000200213877302200215810285772010-01-27       2004    bl ---       0--  u    #d1 aBARREIRO, J. C.  aOxidation of Atrazine by hydrogen Peroxide in the presence of Ferrihydrite and humic acid.  c2004  aCLASSIFICAÇÃO CDD: 630  alNTRODUCTION Oxidation of organic compounds, such as pesticides, have been extensively investigated. In the environment oxidation is facilitated by the presence of oxidants, and abiotic and biotic catalysts, such as enzymes produced by microorganisms. The chemical oxidation mediated by Fenlon-like reactants has been proposed as an active mechanism for pollutant oxidation in soils and sedimenls. In the Fenton-like reaction, Fe(III) is reduced to Fe(II) via hydrogen peroxide (H2O2) or the superoxide anion radical (O2-) with subsequent reaction of H2O2 and Fe(II) to yield hydroxyl radicais ('OH) and Fe(III). Fenton reactions may involve soluble iron (homogeneous reactions) or solid-phase iron mineraIs (helerogeneous reactions), such as ferrihydrite, a naturally occurring mineral  in soil (Huling et aI., 2001).  Humic substances are the major soil organic matter components, comprising a wide diversity wilh respect to structure and functional conligurations. Due to its chemical characteristics, humic subslances can play an important role in the degradation of pesticides. In biological systems, humic substances have been shown to facilitate electron transfer from reduced iron to microbial systems.  Similar redox coupling in Fenlon systems can be provided by humic material constiluents like quinones and hydroquinones. Such reactions may provide an addilional pathway for hydroxyl radical prOduclion during Fe(III) reduction, which may result in a higher rale of degradation of peslicides and other organic pollutants (Huling el aI., 1998).  The aim of this work is to evaluate the effect of humic acids (HA), extracted from Brazilian soil, on the reaclion rate and efficiency of atrazine oxidation by Fenton-like reaction calalyzed by the  presence of the iron oxide ferrihydrite.  aatrazine  aFenton reaction  ahumic acid  ahydroxyl radical  aIron oxide1 aHANSEN, H. C. B.1 aMARTIN-NETO, L.1 aCAPELATO, M. D.  tIn: MARTIN-NETO, L.; MILORI, D.M.B.P.; SILVA, W.T.L. (Ed.). Humic substances and soil and water environment: International Meeting of IHSS, 12. São Carlos : Embrapa Instrumentação Agropecuária, 2004. p. 588-590.