The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO<sub>3</sub>˙<sup>−</sup> as the active intermediate

Burg, Ariela; Shamir, Dror; Shusterman, Inna; Kornweitz, Haya; Meyerstein, Dan

doi:10.1039/c4cc05852f

Cited by 33 publications

(33 citation statements)

References 37 publications

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“…Clearly the unpaired electron density on the carbonates bound to the copper resonates between the three oxygen atoms and has a reasonable probability to be located on the oxygen atoms not bound to the central copper. This implies the role of carbonate as a non‐innocent ligand, which was suggested before during oxidation processes …”

Section: Resultsmentioning

confidence: 58%

“…This impliest he role of carbonate as an on-innocent ligand, which wassuggested before duringo xidation processes. [30][31][32] As [Cu(CO 3 ) n ] 3À2n (n = 2,3) takes part in ar ate-limiting step with the rate law satisfying the second-order kinetics, the possible reactions with regard to this Cu intermediate species are given in Equations (27)- (37). Association: Disproportionation:…”

Section: àmentioning

confidence: 99%

“…It should be noted that Cu II (CO 3 ) n 2À2n is also acatalyst in advanced oxidation processes by H 2 O 2 ,w ith Cu III (CO 3 ) n 3À2n as the active intermediate. [29] Furthermore, it was hoped that the results would enable to clarify whether the carbonates are innocent or noninnocent ligandsi nt his catalytic process, as they are non-innocent ligands in Fenton like reactions [30,31] and in photo-catalytic oxidations on GaN. [32]…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Studies on the Role of [Cu^II(CO₃)_n]²⁻²ⁿ as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

Mizrahi¹,

Maimon

Cohen

et al. 2017

Chemistry A European J

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Recently it was reported that copper bicarbonate/carbonate complexes are good electro-catalysts for water oxidation. However, the results did not enable a decision whether the active oxidant is a Cu or a Cu complex. Kinetic analysis of pulse radiolysis measurements coupled with DFT calculations point out that Cu (CO ) complexes are the active intermediates in the electrolysis of Cu (CO ) solution. The results enable the evaluation of E°[(Cu (CO ) ) ]≈1.42 V versus NHE at pH 8.4. This redox potential is in accord with the electrochemical report. As opposed to literature suggestions for water oxidation, the present results rule out single-electron transfer from Cu (CO ) to yield hydroxyl radicals. Significant charge transfer from the coordinated carbonate to Cu results in the formation of C O by means of a second-order reaction of Cu (CO ) . The results point out that carbonate stabilizes transition-metal cations at high oxidation states, not only as a good sigma donor, but also as a non-innocent ligand.

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Section: Resultsmentioning

confidence: 58%

Section: àmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanistic Studies on the Role of [Cu^II(CO₃)_n]²⁻²ⁿ as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

Mizrahi¹,

Maimon

Cohen

et al. 2017

Chemistry A European J

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“… 2014 50 13096 13099 . 1 This study was the first one to point out that carbonate plays a key role in advanced oxidation processes. Carbonate-Radical-Anions, and Not Hydroxyl Radicals, Are the Products of the Fenton Reaction in Neutral Solutions Containing Bicarbonate Illés E. Mizrahi A.…”

Section: Key Referencesmentioning

confidence: 95%

The Role of Carbonate in Catalytic Oxidations

Mizrahi²,

2020

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Conspectus CO 2 , HCO 3 – , and CO 3 2– are present in all aqueous media at pH > 4 if no major effort is made to remove them. Usually the presence of CO 2 /HCO 3 – /CO 3 2– is either forgotten or considered only as a buffer or proton transfer catalyst. Results obtained in the last decades point out that carbonates are key participants in a variety of oxidation processes. This was first attributed to the formation of carbonate anion radicals via the reaction OH • + CO 3 2– → CO 3 •– + OH – . However, recent studies point out that the involvement of carbonates in oxidation processes is more fundamental. Thus, the presence of HCO 3 – /CO 3 2– changes the mechanisms of Fenton and Fenton-like reactions to yield CO 3 •– directly even at very low HCO 3 – /CO 3 2– concentrations. CO 3 •– is a considerably weaker oxidizing agent than the hydroxyl radical and therefore a considerably more selective oxidizing agent. This requires reconsideration of the sources of oxidative stress in biological systems and might explain the selective damage induced during oxidative stress. The lower oxidation potential of CO 3 •– probably also explains why not all pollutants are eliminated in many advanced oxidation technologies and requires rethinking of the optimal choice of the technologies applied. The role of percarbonate in Fenton-like processes and in advanced oxidation processes is discussed and has to be re-evaluated. Carbonate as a ligand stabilizes transition metal complexes in uncommon high oxidation states. These high-valent complexes are intermediates in electrochemical water oxidation processes that are of importance in the development of new water splitting technologies. HCO 3 – and CO 3 2– are also very good hole scavengers in photochemical processes of semiconductors and may thus become key participants in the development of new processes for solar energy conversion. In this Account, an attempt to correlate these observations with the properties of carbonates is made. Clearly, further studies are essential to fully uncover the potential of HCO 3 – /CO 3 2– in desired oxidation processes.

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“…Structures of these radical complexes are given in Figure 2. It was experimentally proved that Co II is not oxidized during Fenton-like reaction, 24 …”

Section: •−mentioning

confidence: 99%

Plausible Mechanisms of the Fenton-Like Reactions, M = Fe(II) and Co(II), in the Presence of RCO₂^– Substrates: Are OH^• Radicals Formed in the Process?

2015

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The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO₃˙⁻ as the active intermediate

Cited by 33 publications

References 37 publications

Mechanistic Studies on the Role of [Cu^II(CO₃)_n]²⁻²ⁿ as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

Mechanistic Studies on the Role of [Cu^II(CO₃)_n]²⁻²ⁿ as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

The Role of Carbonate in Catalytic Oxidations

Plausible Mechanisms of the Fenton-Like Reactions, M = Fe(II) and Co(II), in the Presence of RCO₂^– Substrates: Are OH^• Radicals Formed in the Process?

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The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO3˙− as the active intermediate

Cited by 33 publications

References 37 publications

Mechanistic Studies on the Role of [CuII(CO3)n]2−2n as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

Mechanistic Studies on the Role of [CuII(CO3)n]2−2n as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

The Role of Carbonate in Catalytic Oxidations

Plausible Mechanisms of the Fenton-Like Reactions, M = Fe(II) and Co(II), in the Presence of RCO2– Substrates: Are OH• Radicals Formed in the Process?

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The role of carbonate as a catalyst of Fenton-like reactions in AOP processes: CO₃˙⁻ as the active intermediate

Mechanistic Studies on the Role of [Cu^II(CO₃)_n]²⁻²ⁿ as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

Mechanistic Studies on the Role of [Cu^II(CO₃)_n]²⁻²ⁿ as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

Plausible Mechanisms of the Fenton-Like Reactions, M = Fe(II) and Co(II), in the Presence of RCO₂^– Substrates: Are OH^• Radicals Formed in the Process?