Electrochemical characterization of oxygen reduction by FeII[ethylenediaminetetraacetate]

Laine, Derek F.; McAllister, Simon D.; Cheng, I. Francis

doi:10.1016/j.jelechem.2007.05.012

Cited by 7 publications

(10 citation statements)

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“…The optimal complex for O 2 reduction is presumed to be a protonated form, Fe II EDTA(H) whereas above pH 8 the hydroxylated forms of FeEDTA (Fe II EDTA(OH) and Fe II EDTA(OH) 2 ) tend to predominate (see Figure ). In terms of the former, protonation of one of the carboxylate arms of EDTA will create an open metal-centered site for the coordination of O 2 . , Hydrolyzed forms of Fe II EDTA may prevent coordination of O 2 (Figure ). , …”

Section: Resultsmentioning

confidence: 99%

“…In this case, the formation of HO• and H 2 O 2 in the ZEA system is hypothesized to be driven primarily by the Fe II EDTA complex. This assumption is based off of literature sources that indicate many Fe(II) complexes are able to reduce O 2 to ROS. – In the ZEA system, Fe II EDTA forms as a result of the presence of EDTA which complexes Fe 2+ produced from the dissolution of Fe(0) (reactions and ). In turn, Fe II EDTA reduces O 2 as in reactions and .…”

Section: Introductionmentioning

confidence: 99%

“…This assumption is based off of literature sources that indicate many Fe(II) complexes are able to reduce O 2 to ROS. – In the ZEA system, Fe II EDTA forms as a result of the presence of EDTA which complexes Fe 2+ produced from the dissolution of Fe(0) (reactions and ). In turn, Fe II EDTA reduces O 2 as in reactions and . The next logical steps are the formation of H 2 O 2 from reduction of O 2 or O 2 •− (reactions and ) followed by the Fenton reaction releasing HO• (reaction ).…”

Section: Introductionmentioning

confidence: 99%

“…This assumption is based off of literature sources that indicate many Fe(II) complexes are able to reduce O 2 to ROS. [22][23][24][25][26][27][28][29][30][31] In the ZEA system, Fe II EDTA forms as a result of the presence of EDTA which complexes Fe 2+ produced from the dissolution of Fe(0) (reactions 1 and 2). In turn, Fe II EDTA reduces O 2 as in reactions 3 and 4.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H₂O₂, HO•, and the Homogeneous Activation of O₂ by Fe^IIEDTA

Laine

Blumenfeld

Cheng

2008

Ind. Eng. Chem. Res.

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The ZEA (zero valent iron, ethylenediaminetetraacetic acid (EDTA), and air) organic pollutant degradation system has been previously shown to degrade a variety of organic pollutants and chemical warfare agent surrogates; however, mechanistic details and reactive intermediates formed in this system have not been identified. It is hypothesized that the ZEA system produces reactive oxygen species (H2O2, HO•) by the reduction of oxygen by FeIIEDTA(aq). This hypothesis is examined through an electrochemical model of the ZEA system. A carbon basket electrode is used as the reducing agent in place of Fe(0). The FeIIIEDTA complex (0.5 mM) is electrochemically reduced to FeIIEDTA at an applied potential of −120 mV (vs Ag/AgCl) under aerobic conditions. Hydrogen peroxide was observed to form in the presence of the metal complex with a maximum concentration reaching 0.139 mM H2O2 after 3 h of electrolysis. In the absence of FeEDTA, 0.04 mM H2O2 is obtained by the direct reduction of O2 at the electrode surface. Electron resonance spectroscopy (ESR), along with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap and methanol as a radical scavenger confirms the formation of HO• produced via the Fenton reaction in the electrochemical system. Hydroxyl radical attack on EDTA caused the degradation of FeII/IIIEDTA to a steady-state concentration of 0.14 mM from 0.5 mM as observed by HPLC. The pH of the electrolysis solution increased from 2.64 to 9.25 during 6 h of reductive electrolysis which is indicative of the consumption of H+ during the reduction of O2 to form H2O2. These experiments provide evidence that the ZEA system uses atmospheric O2 to produce reactive oxygen species including those that deeply oxidize organics under room temperature and pressure conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H₂O₂, HO•, and the Homogeneous Activation of O₂ by Fe^IIEDTA

Laine

Blumenfeld

Cheng

2008

Ind. Eng. Chem. Res.

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“…5 is that for Fe(edta) 2À which is unique in that the reactions with O 2 and _NO exhibit a complicated acid dependence. 66,70 Also, additional problems arise from the inseparability of O 2 binding step from the rapid follow-up reactions with the second molecule of Fe II (edta). As a result, only an estimate for K O 2 $10 4 M À1 was reported for a limited set of concentrations at pH 6.…”

Section: àmentioning

confidence: 99%

Kinetics and thermodynamics of nitric oxide binding to transition metal complexes. Relationship to dioxygen binding

et al. 2013

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The kinetics and activation parameters for_NO dissociation from L(H 2 O)Co(NO) 2+ 2+ , and Cr(H 2 O) 5 NO 2+ were determined in aqueous solution in the presence of IrCl 6 2À , IrBr 6 2À , or O 2 as scavengers for _NO and/or metal(II) complexes. The rate constants k -NO at 25 C are (5.7 AE 0.1) Â 10 À3 s À1 for L 2 (H 2 O)Co(NO) 2+ , (1.0 AE 0.1) Â 10 À4 for L 1 (H 2 O) Co(NO) 2+ , (5.9 AE 2.0) Â 10 À8 for Cr(H 2 O) 5 NO 2+ and (3.5 AE 1.8) Â 10 À9 s À1 for L 2 (H 2 O)Rh(NO) 2+ . The kinetics of the reverse reaction were determined by laser flash photolysis at 25 C, k NO ¼ (1.7 AE 0.2) Â 10 7 M À1 s À1 for L 2 Co(H 2 O) 2 2+ and (1.8 AE 0.1) Â 10 8 M À1 s À1 for L 2 (H 2 O)Rh 2+ . The rate constants k NO and k -NO obtained here and those available in the literature were used to calculate the equilibrium binding constants K NO for a series of nitrosyl metal complexes. A good correlation was found between log K NO and log K O 2 , the latter corresponding to O 2 binding. The correlation includes complexes of four different transition metals as well as hydrogen atom, and covers a range of about 3 V in reduction potentials. The implications of these results are discussed.

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Electrochemical detection of triacetone triperoxide employing the electrocatalytic reaction of iron(II/III)-ethylenediaminetetraacetate and hydrogen peroxide

Laine

Roske

Cheng

2008

Analytica Chimica Acta

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Electrochemical characterization of oxygen reduction by FeII[ethylenediaminetetraacetate]

Cited by 7 publications

References 29 publications

Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H₂O₂, HO•, and the Homogeneous Activation of O₂ by Fe^IIEDTA

Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H₂O₂, HO•, and the Homogeneous Activation of O₂ by Fe^IIEDTA

Kinetics and thermodynamics of nitric oxide binding to transition metal complexes. Relationship to dioxygen binding

Electrochemical detection of triacetone triperoxide employing the electrocatalytic reaction of iron(II/III)-ethylenediaminetetraacetate and hydrogen peroxide

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Electrochemical characterization of oxygen reduction by FeII[ethylenediaminetetraacetate]

Cited by 7 publications

References 29 publications

Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H2O2, HO•, and the Homogeneous Activation of O2 by FeIIEDTA

Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H2O2, HO•, and the Homogeneous Activation of O2 by FeIIEDTA

Kinetics and thermodynamics of nitric oxide binding to transition metal complexes. Relationship to dioxygen binding

Electrochemical detection of triacetone triperoxide employing the electrocatalytic reaction of iron(II/III)-ethylenediaminetetraacetate and hydrogen peroxide

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Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H₂O₂, HO•, and the Homogeneous Activation of O₂ by Fe^IIEDTA

Mechanistic Study of the ZEA Organic Pollutant Degradation System: Evidence for H₂O₂, HO•, and the Homogeneous Activation of O₂ by Fe^IIEDTA