title: Degradation and mineralization of sulcotrione and mesotrione in aqueous medium by the electro-Fenton process: a kinetic study.
abstract: BACKGROUND
  The degradation and mineralization of two triketone (TRK) herbicides, including sulcotrione and mesotrione, by the electro-Fenton process (electro-Fenton using Pt anode (EF-Pt), electro-Fenton with BDD anode (EF-BDD) and anodic oxidation with BDD anode) were investigated in acidic aqueous medium.
  
  
  METHODS
  The reactivity of both herbicides toward hydroxyl radicals was found to depend on the electron-withdrawing effect of the aromatic chlorine or nitro substituents. The degradation of sulcotrione and mesotrione obeyed apparent first-order reaction kinetics, and their absolute rate constants with hydroxyl radicals at pH 3.0 were determined by the competitive kinetics method.
  
  
  CONCLUSIONS
  The hydroxylation absolute rate constant (k(abs)) values of both TRK herbicides ranged from 8.20 × 10(8) (sulcotrione) to 1.01 × 10(9) (mesotrione) L mol(-1) s(-1), whereas those of the TRK main cyclic or aromatic by-products, namely cyclohexane 1,3-dione, (2-chloro-4-methylsulphonyl) benzoic acid and 4-(methylsulphonyl)-2-nitrobenzoic acid, comprised between 5.90 × 10(8) and 3.29 × 10(9) L mol(-1) s(-1). The efficiency of mineralization of aqueous solutions of both TRK herbicides was evaluated in terms of total organic carbon removal. Mineralization yields of about 97-98% were reached in optimal conditions for a 6-h electro-Fenton treatment time.
  
  
  CONCLUSIONS
  The mineralization process steps involved the oxidative opening of the aromatic or cyclic TRK by-products, leading to the formation of short-chain carboxylic acids, and, then, of carbon dioxide and inorganic ions.
authors: Laboratoire Géomatériaux et Environnement, Université Paris-Est, Marne-La-Vallée, France.
authors: Minir
authors: M
authors: Murati
authors: Nihal
authors: N
authors: Oturan
authors: Jean-Jacques
authors: JJ
authors: Aaron
authors: Ahmad
authors: A
authors: Dirany
authors: Bruno
authors: B
authors: Tassin
authors: Zoran
authors: Z
authors: Zdravkovski
authors: Mehmet A
authors: MA
authors: Oturan
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry; D003512:Cyclohexanones / Q000737:chemistry*; D004566:Electrodes; D006540:Herbicides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D007700:Kinetics; D008698:Mesylates / Q000737:chemistry*; D012996:Solutions; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods
chemical_list: D002264:Carboxylic Acids; D003512:Cyclohexanones; D006540:Herbicides; D008698:Mesylates; D012996:Solutions; D014874:Water Pollutants, Chemical; C432907:mesotrione; C079906:sulcotrione