Reaction of hydroxyl radicals with ammonia in liquid water at elevated temperatures

Hickel, B.; Sehested, Κ.

doi:10.1016/1359-0197(92)90244-a

Cited by 15 publications

(23 citation statements)

References 14 publications

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“…The rate constant for OH • dimerization (k = 5.5 · 10 9 M )1 s )1 ) is greater than k 17 = 1 · 10 8 M )1 s )1 [35,36]. However, the ammonia concentrations, 126-1044 lM, are many orders of magnitude greater than the expected steady state concentration of OH • , which ensures that dimerization of OH • does not contribute significantly to the reaction.…”

Section: Scheme I Reduction Of Fe Speciesmentioning

confidence: 92%

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Sharma

Chenay

2005

J Appl Electrochem

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Resultsof the heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated TiO 2 suspensions in the presence of ammonia are presented. The initial rate of Fe(VI) reduction, R, may be expressed as R = k Fe(VI) [Fe(VI)] 1.25 where k Fe(VI) = [Ammonia]/(a[Ammonia]+b), a = 6.0 · 10 3 lM 0.25 s and b = 4.1 · 10 6 lM )1.25 s )1 . The rate constant, k Fe(VI) , increases with the ammonia concentration. The photocatalytic oxidation of ammonia is enhanced in the presence of Fe(VI). A mechanism involving Fe(V) as a reactive intermediate is presented which explains the faster photocatalytic oxidation of ammonia in the presence of Fe(VI).

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Section: Scheme I Reduction Of Fe Speciesmentioning

confidence: 92%

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Sharma

Chenay

2005

J Appl Electrochem

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“…(14)) rather than dimerizing to form hydrogen peroxide. The rate constant for OH • dimerization (k = 5.5 × 10 9 M −1 s −1 ) is greater than k 14 = 1 × 10 8 M −1 s −1 [55,56]. However, the ammonia concentration, 9.4 × 10 −4 M, is many orders of magnitude greater than the expected steady state concentration of OH • , which ensures that dimerization of OH • does not contribute significantly to the reaction.…”

Section: Reduction Of Fe Speciesmentioning

confidence: 93%

Heterogeneous photocatalytic reduction of ferrate(VI) in UV‐irradiated titania suspensions: Role in enhancing destruction of nitrogen‐containing pollutants

Sharma

Winkelmann

Krasnova

et al. 2003

International Journal of Photoenergy

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Abstract. The results of the heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated TiO 2 suspensions are presented and suggest indirect observation of the formation of Fe(V) by the photoreduction of Fe(VI) with e cb − at TiO 2 surfaces. Because Fe(V) selectively and rapidly oxidizes low reactivity pollutants with the production of the non-toxic by-product, Fe(III), the photocatalytic reduction of Fe(VI) has a role in pollution remediation processes. The experiments were conducted as a function of TiO 2 suspension concentrations, Fe(VI) concentrations, and pH in basic media. The initial rate of Fe(VI) reduction gave a fractional order with respect to initial Fe(VI) concentrations and adheres to simple Langmuir-Hinshelwood kinetics.Results suggest that the surface reaction (Fe(VI) + e cb − → Fe(V)) is the rate-controlling step. The photocatalytic reduction of Fe(VI) in the presence of less reactive nitrogen-containing species (ammonia, cyanate, and fulvic acid) were also investigated. Enhancement in the rate of Fe(VI) reduction was observed. A reaction scheme involving Fe(V) as an intermediate is presented which explains the faster photocatalytic oxidation of pollutants in the presence of Fe(VI).

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“…Other data have been derived as indicated in the footnotes and explained below. Here it is worth recalling that for negative Bions the free energy of formation in aqueous solution, AfGO(,,) is given by the free energy change in reaction [6] [7] and [8] ) . These equations are needed for the calculation of the properties in Table 5.…”

Section: Thermodynamic Datamentioning

confidence: 99%

“…~i " ' + NH20H + ~i " + NH2' + OHor in pulse radiolysis by abstraction of H atoms from NH3 with OH' (7,8) PI OH' + NH3 + H 2 0 + NH2' NH3'+ cations can be made by photolysis of NH3 complex ions (1,9), e.g., Radicals produced by those methods have been examined by polarography (10,11) and ESR (12,13), and the kinetics of some of their reactions have been investigated by fast-reaction techniques (6)(7)(8)(9)13). Extensive gas phase investigations on the species have been conducted (14)(15)(16) and theoretical calculations on their energies and structures have been made at relatively high level (17).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Gas and solution phase thermochemistry and transition energies of NH₂^• and NH₃^•+, and their aquo complexes: an ab initio study

Yu¹,

Rauk²

1994

Can. J. Chem.

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DAKE Yu, ARVI RAUK and DAVID A. ARMSTRONG. Can. J. Chem. 72, 471 (1994). IAb i n~t~o calculations were performed on several aquo complexes of NH,', and NH3'+, and on monomeric parent species. The geometries were optimized at the HF16-31+G* level and the vibrational frequencies were calculated. The total energies and the binding energies of complexes were evaluated at the MP216-31+G* + ZPE level of theory. Gas and aqueous solution phase thermodynamic properites of NH,' and NH3'+ and several other species were calculated. The examination of solution phase properties of the radicals was facilitated by study of the structures and transition energies of aquo complexes. H- [Traduit par la rCdaction]

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Reaction of hydroxyl radicals with ammonia in liquid water at elevated temperatures

Cited by 15 publications

References 14 publications

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Heterogeneous photocatalytic reduction of ferrate(VI) in UV‐irradiated titania suspensions: Role in enhancing destruction of nitrogen‐containing pollutants

Gas and solution phase thermochemistry and transition energies of NH₂^• and NH₃^•+, and their aquo complexes: an ab initio study

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Reaction of hydroxyl radicals with ammonia in liquid water at elevated temperatures

Cited by 15 publications

References 14 publications

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Heterogeneous photocatalytic reduction of ferrate(VI) in UV‐irradiated titania suspensions: Role in enhancing destruction of nitrogen‐containing pollutants

Gas and solution phase thermochemistry and transition energies of NH2• and NH3•+, and their aquo complexes: an ab initio study

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Gas and solution phase thermochemistry and transition energies of NH₂^• and NH₃^•+, and their aquo complexes: an ab initio study