Oxidation kinetics of FeII-EDTA and FeII-NTA chelates by dissolved oxygen

Sada, Eizô; Kumazawa, H.; Machida, Hiroshi

doi:10.1021/ie00067a033

Cited by 68 publications

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“…9 In addition, all studies imply that the reaction is first order with respect to oxygen. [5][6][7][8][9][10] This work describes a kinetic study on the reaction of C Fe II (EDTA) with oxygen under conditions relevant to the BiodeNOx process (C Fe II (EDTA) ) 15-60 mol/m 3 , P O2 ) 5-20 kPa, pH ) 5-8, T ) 298-328 K, and C NaCl ) 0-15 kg/m 3 ). Although various studies have been performed in the past, the results are not always reliable because of improper attention to mass transfer issues.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Reaction of Fe^II(EDTA) with Oxygen in Aqueous Solutions

Gambardella¹,

Ganzeveld

Winkelman³

et al. 2005

Ind. Eng. Chem. Res.

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The kinetics of the reaction of oxygen with aqueous Fe II (EDTA) solutions has been determined in a range of process conditions (C Fe II (EDTA) ) 15-60 mol/m 3 , P O2 ) 5-20 kPa, pH ) 5-8, T ) 298-328 K, C NaCl ) 0-15 kg/m 3 ) using a gas-liquid stirred cell reactor. The oxygen absorption rates were modeled using an expression derived by De Coursey using the penetration theory of mass transfer. Within the range of process conditions applied, the reaction was shown to be first order in oxygen and second order in iron chelate. The temperature dependence of the kinetic constant may be expressed as (pH ) 7, no salt addition): k 12 ) 5.3 × 10 3 e -4098/T m 6 /(mol 2 ‚s). The kinetic constant is essentially independent of the pH in the range 5 < pH < 8. When applying a NaCl concentration of 15 kg/m 3 , the kinetic constant increases ∼35% (T ) 328 K). The oxidation of Fe II (EDTA) to Fe III (EDTA) is not the sole oxygen-consuming reaction. The extent of side reactions, possibly related to EDTA ligand degradation, is a function of the pH and the oxygen concentration. A remarkable, unprecedented step change in the selectivity of the reaction was observed when the reaction was performed at a higher oxygen concentration.

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Section: Introductionmentioning

confidence: 99%

Kinetics of the Reaction of Fe^II(EDTA) with Oxygen in Aqueous Solutions

Gambardella¹,

Ganzeveld

Winkelman³

et al. 2005

Ind. Eng. Chem. Res.

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“…The removal of N O during simultaneous absorption of NO and SO, could be predicted from corresponding experimental results for absorption of only NO into an absorbent of the same pH value. Regarding reaction kinetics, the reduction of Fe(II1) to Fe(I1) by HS03-with coexisting EDTA, the oxidation of Fe(1I) to Fe(II1) by N O in the presence of Na,SO,, and the oxidation of Fe(I1)EDTA by dissolved oxygen were investigated (Sada et al, 1986(Sada et al, , 1987.In view of the results of our earlier fundamental work cited above, there are two important considerations that emerge in the simultaneous N O and SO, removal process: 1. To keep the level of the concentration of Fe(I1) as high as possible and for this purpose, to reduce a portion of the effluent Correspondence concerning this paper should be addressed to E. Sada stream by sulfite a t the boiling temperature in the outer loop of the absorber…”

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confidence: 99%

Simultaneous removal of NO and SO₂ by absorption into aqueous mixed solutions

1988

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Currently, nitric oxide and sulfur dioxide emitted from stationary combustion facilities have been removed separately by selective catalytic reduction processes and wet scrubbing processes. There is no practical process successful for simultaneous removal of N O and SO2. Since scrubbing soiutions for wet NO removal also remove SO,, wet scrubbing processes are potential candidates for simultaneous NO and SO, removal. For instance, by use of liquid-phase reaction sequences in which both dissolved N O and SO, participate, simultaneous removal of both the gases can be achieved effectively in a single step or equipment. Aqueous solutions of Na,SO, with added Fe(I1)EDTA (ferrous ion coordinated to ethylenediaminetetraacetic acid) seem to be promising absorbents to fulfill such a possibility. To establish the procedure for inevitable regeneration or treatment of spent adsorbent, it is necessary to clarify the whole scheme of the liquid phase complicated reactions.In our previous work (Sada et al., 1984(Sada et al., , 1986, the pathways of the liquid-phase reactions were completed and presented in the form of a map. The degree of removal of NO was found to depend on the concentration of Fe(II), which was determined from a balance of oxidation and reduction rates of iron. The removal of N O during simultaneous absorption of NO and SO, could be predicted from corresponding experimental results for absorption of only NO into an absorbent of the same pH value. Regarding reaction kinetics, the reduction of Fe(II1) to Fe(I1) by HS03-with coexisting EDTA, the oxidation of Fe(1I) to Fe(II1) by N O in the presence of Na,SO,, and the oxidation of Fe(I1)EDTA by dissolved oxygen were investigated (Sada et al., 1986(Sada et al., , 1987.In view of the results of our earlier fundamental work cited above, there are two important considerations that emerge in the simultaneous N O and SO, removal process: 1. To keep the level of the concentration of Fe(I1) as high as possible and for this purpose, to reduce a portion of the effluent Correspondence concerning this paper should be addressed to E. Sada stream by sulfite a t the boiling temperature in the outer loop of the absorberThe former is required from the'experimental result that the degree of N O removal mainly depends on the concentration of Fe(I1). The latter is necessary because of the pH of the absorbent is decreased by simultaneously absorbed SO,.In the present work, the process flow diagram for simultaneous removal of N O and SO2 by absorption into an aqueous solution of Na,SO, with added Fe(I1)EDTA was first proposed on the basis of our earlier fundamental work. Secondly, to put this simultaneous removal process into practical application, long-term absorption tests and the regeneration of (simulated) spent liquor by reduction at its boiling temperature were undertaken.2. to control the pH of the absorvent. Background of Simltaneous NO and SO, Removal ProcessThe wet scrubbing method generally has a significant disadvantage of inevitable waste-liquor treatment, so that the proce...

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“…Thus the superoxo species proure 3a). Moreover, the substitution of coordinated H 2 O by duced in (4) may react further as shown in (6). The rate law O 2 on the [Fe II (cdta)] complexes is not expected to cause a for these reactions will be similar to that in (5), as summasignificant UV-Vis spectral change.…”

Section: Kinetic Measurementsmentioning

confidence: 95%

“…[4,6,7,10,12,21] text was their importance in several biochemical processes, for example the cleavage of DNA, the decomposition of H 2 O 2 or the dismutation of superoxide.…”

Section: Introductionmentioning

confidence: 99%

Multistep Oxidation Kinetics of [FeII(cdta)] [cdta =N,N′,N′′,N′′′-(1,2-Cyclohexanediamine)tetraacetate] with Molecular Oxygen

Seibig¹,

Eldik²

1999

Eur. J. Inorg. Chem.

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The complicated oxidation kinetics of the reaction of [FeII(cdta)] [cdta = 1,2‐(N,N′‐ cyclohexanediamine)tetraacetate] with molecular oxygen was investigated as a function of [FeII], [O2], pH, temperature and pressure. In the presence of an excess of [FeII(cdta)] three steps could be observed, for which the following rate constants were found at 25°C; k1 = 1080 ± 16 M−1 s−1, k2 = 103 ± 4 M−1 s−1 and k3 = 59 ± 5 M−1 s−1. These reaction steps can be accounted for in terms of the following mechanism: (1) [FeII(cdta)H2O]2– reacts with O2 by a substitution process to form [FeII(cdta)O2]2–; (2) electron‐transfer to form an FeIII‐superoxo species; (3) subsequent bridge formation followed by electron‐transfer to give [(cdta)FeIII‐O22–‐FeIII(cdta)]4–; and (4) a fast decomposition of the peroxide intermediate yielding the monomeric [FeIII(cdta)] and H2O2. Rate and activation parameters for these steps are reported and discussed in terms of the postulated mechanism and in reference to available literature data.

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Oxidation kinetics of FeII-EDTA and FeII-NTA chelates by dissolved oxygen

Cited by 68 publications

References 0 publications

Kinetics of the Reaction of Fe^II(EDTA) with Oxygen in Aqueous Solutions

Kinetics of the Reaction of Fe^II(EDTA) with Oxygen in Aqueous Solutions

Simultaneous removal of NO and SO₂ by absorption into aqueous mixed solutions

Multistep Oxidation Kinetics of [FeII(cdta)] [cdta =N,N′,N′′,N′′′-(1,2-Cyclohexanediamine)tetraacetate] with Molecular Oxygen

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Oxidation kinetics of FeII-EDTA and FeII-NTA chelates by dissolved oxygen

Cited by 68 publications

References 0 publications

Kinetics of the Reaction of FeII(EDTA) with Oxygen in Aqueous Solutions

Kinetics of the Reaction of FeII(EDTA) with Oxygen in Aqueous Solutions

Simultaneous removal of NO and SO2 by absorption into aqueous mixed solutions

Multistep Oxidation Kinetics of [FeII(cdta)] [cdta =N,N′,N′′,N′′′-(1,2-Cyclohexanediamine)tetraacetate] with Molecular Oxygen

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Kinetics of the Reaction of Fe^II(EDTA) with Oxygen in Aqueous Solutions

Kinetics of the Reaction of Fe^II(EDTA) with Oxygen in Aqueous Solutions

Simultaneous removal of NO and SO₂ by absorption into aqueous mixed solutions