DFT study of the entire reaction cycle of H2O2 decomposition and O2 generation catalyzed by fenton reagent
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ARSENE, Ion, GORINCHOY, Natalia. DFT study of the entire reaction cycle of H2O2 decomposition and O2 generation catalyzed by fenton reagent. In: The International Conference dedicated to the 55th anniversary from the foundation of the Institute of Chemistry of the Academy of Sciences of Moldova, 28-30 mai 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Chimie al AȘM, 2014, p. 52.
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The International Conference dedicated to the 55th anniversary from the foundation of the Institute of Chemistry of the Academy of Sciences of Moldova 2014
Conferința "The International Conference dedicated to the 55th anniversary from the foundation of the Institute of Chemistry of the Academy of Sciences of Moldova"
Chișinău, Moldova, 28-30 mai 2014

DFT study of the entire reaction cycle of H2O2 decomposition and O2 generation catalyzed by fenton reagent


Pag. 52-52

Arsene Ion, Gorinchoy Natalia
 
Institute of Chemistry of the Academy of Sciences of Moldova
 
Disponibil în IBN: 21 ianuarie 2019


Rezumat

On the base of density functional theory (DFT) calculations the four-stage mechanism for the oxygen production and the Fe2+ regeneration in the Fenton reaction is proposed (Scheme 1): 1) [Fe(II)(H2O)6]2+―H2O2 (1) = TS-i = [Fe(IV)(H2O)4(OH)2]2+(2)+ 2H2O 2) [Fe(IV)(H2O)4(OH)2]2+―H2O2 (3) = TS-ii =[Fe(III)(H2O)5-OH]2+―HO2(4) 3) [Fe(III)(H2O)5(OH)]2+―H2O2 (5) = TS-iii =[Fe(II)(H2O)6]2+―HO2 (6) 4) HO2―HO2 (7) = TS-iv = H2O2―O2 (8) The DFT calculations of all the species involved in reactions (1)-(4) were performed with the PRIRODA 06 program [1] using the PBE functional [2] and the implemented in the PRIRODA 06 package basis set L1 which is an analog of the Dunning double-zeta basis sets ccpVDZ [3]. The transition state for each step of the entire reaction cycle was localized and verified by intrinsic reaction coordinate analysis. It is shown that the O-O bond cleavage of coordinated H2O2 at the first step of reaction does not lead to free OH radicals. Instead, a highly reactive intermediate [Fe(IV)(H2O)4(OH)2]2+ with two OH radicals “trapped” in the complex is formed with the energy barrier of 14.9 kcal/mol. The result of the next two reaction steps is the formation of the two HO2 radicals which can react on the triplet energy surface in order to produce O2 in the triplet ground state and a H2O2 molecule. The overall reaction, 2H2O2=2H2O+O2 with the complex [Fe(II)(H2O)6]2+ regeneration, is the exothermic process with the energy gain 43.8 kcal/mol.