Concerning the formation of hydrogen in nuclear waste. Quantitative generation of hydrogen via a Cannizzaro intermediate

Ashby, E. C.; Doctorovich, Fabio; Liotta, Charles L.; Neumann, H. M.; Barefield, E. Kent; Konda, Atsuo; Zhang, Kai; Hurley, J.D.; Siemer, Darryl D.

doi:10.1021/ja00056a065

Cited by 79 publications

(77 citation statements)

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“…We provide effective rate constants and activation energies for the H2 production reaction of these two substrates. We further verify that the mechanism for this reaction utilizes one water proton in the case of glyoxylate, as proposed earlier, 12 , 13 but not in the case GI formaldehyde.…”

Section: Introductionsupporting

confidence: 88%

“…It has been shown that formaldehyde in basic aqueous solutions will generate dihydrogen.10,11 Efforts at Georgia Tech have established that formaldehyde and similar aldehydes may quantitatively be converted to hydrogen at extremely high concentrations of hydroxide.12, 13 In this section we provide quantitative descriptions of the reactions of formaldehyde and glyoxylate and attempt to shed further light on the mechanism of their hydrogengenerating reaction. We provide effective rate constants and activation energies for the H2 production reaction of these two substrates.…”

Section: Introductionmentioning

confidence: 99%

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Radiolytic and radiolytically induced generation of gases from synthetic wastes. Final report

Meisel¹,

Jonah²,

Kapoor³

et al. 1993

150

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Section: Introductionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Radiolytic and radiolytically induced generation of gases from synthetic wastes. Final report

Meisel¹,

Jonah²,

Kapoor³

et al. 1993

150

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“…The thermal and radiolytic oxidation of organic compounds in simulated Hanford wastes have been studied extensively (Ashby et al 1992(Ashby et al , 1993(Ashby et al ,1994Barefield et al 1995Barefield et al , 1996Bryan et al 1993;Bryan and Pederson 1994;Camaioni et al 1995Camaioni et al ,1996Camaioni et al ,1997Delegard 1980Delegard ,1987Meisel et al 1991aMeisel et al , 1991bMeisel et al , 1992Meisel et al , 1993Meisel et al , 1997. The reactivity order for thermal degradation of the complexants, which encompasses all the pathways for the decomposition of the organic constituents in the waste in the absence of radiation, has been given as (Camaioni et al 1996):…”

Section: General Features Of Organic Reactions In Hanford Wastesmentioning

confidence: 99%

“…Zonic Reactions. The base-catalyzed ionic oxidation reactions of organic complexants, The oxidation of the organic molecules with hydroxyl groups, including citrate, glycolate, and HEDTA anions by nitrite ions promoted by the aluminate ion, has been proposed to account for their decomposition in the absence of radiation (Ashby et al 1993(Ashby et al , 1994Barefield et al 1995Barefield et al , 1996Delegard 1980). The transfer of hydrogen from the organic constituent to the nitrito ligand is greatly facilitated by the coordination of both molecular units to the aluminate ion.…”

Section: Pathways To Aged Oxidized Organic Compoundsmentioning

confidence: 99%

“…[ 1994,1995,19961) Hydrolysis reactions are also important in Hanford wastes. The amides and nitriles formed from fragmentation of complexants are hydrolyzed under the conditions of storage (Ashby et al 1993(Ashby et al ,1994Barefield et al 1995Barefield et al ,1996Camaioni et al 1997). Acetals and the analogous nitrogenous derivatives formed as intiermediates on several reaction pathways are also susceptible to hydrolysis.…”

Section: Pathways To Aged Oxidized Organic Compoundsmentioning

confidence: 99%

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Chemical pathways for the formation of ammonia in Hanford wastes

Stock¹,

Pederson²

1997

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This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important).Reduction of nitrite ions is believed to be the most important source of ammonia. Whether by radiolytic or thermal routes, nitrite reduction reactions proceed through nitrogen dioxide, nitric oxide, the nitrosyl anion, and the hyponitrite anion. Nitrite ion is also converted into hydroxylamine, another important intermediate on the pathway to form ammonia. These reaction pathways additionally result in the formation of nitrous oxide and molecular nitrogen, whereas hydrogen formation is produced in a separate reaction sequence.The oxidative degradation of trisodium EDTA and tetrasodium HEDTA also yields ammonia and other nitrogenous gases. The complexants react with nitric oxide and nitrogen dioxide to produce oxidized compounds that subsequently undergo hydrolysis, eventually liberating ammonia. Amides and nitriles are intermediates in these long reaction sequences. , The direct reaction of hydrogen with nitrous oxide and nitrogen can account for only negligible quantities of ammonia in Hanford tanks. Thermal reactions require high temperatures (AOOOC), high pressures, and the presence of catalysts, to proceed at significant rates. Similarly, radiolytic yields for direct reactions of hydrogen with nitrogen and nitrous oxide under tank conditions are expected to be very small.Oxygen can substantially alter the yields of nitrogenous gases. Two principal pathways have been identified. Oxygen intercepts radicals produced in thermal and radiolytic reactions that would otherwise eventually result in the formation of nitrogen, nitrous oxide and ammonia. Oxygen also reacts directly with complexants and intermediates to yield oxalate ion. The hydrogen yield is often increased in the presence of oxygen.

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Aerobic, Copper‐Mediated Oxidation of Alkaline Formaldehyde to Fuel‐Cell Grade Hydrogen and Formate: Mechanism and Applications

Preti

Squarcialupi²,

Fachinetti

2009

Angewandte Chemie

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Jenseits von Nanopulvern: Wasserstoff und Formiat entstehen bei der Oxidation von alkalischem HCHO durch CuO‐Mikropartikel. Die durch rein elektrochemische Reduktion von CuO gebildeten Cu‐Mikropartikel behalten die Morphologie von CuO bei (linkes Bild: CuO; rechtes Bild: durch Reduktion von CuO durch alkalisches HCHO gebildetes Cu) und sind gasdurchlässig. Sie reagieren effizienter als Cu‐Nanopartikel mit Luft zu CuO zurück.magnified image

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Concerning the formation of hydrogen in nuclear waste. Quantitative generation of hydrogen via a Cannizzaro intermediate

Cited by 79 publications

References 0 publications

Radiolytic and radiolytically induced generation of gases from synthetic wastes. Final report

Radiolytic and radiolytically induced generation of gases from synthetic wastes. Final report

Chemical pathways for the formation of ammonia in Hanford wastes

Aerobic, Copper‐Mediated Oxidation of Alkaline Formaldehyde to Fuel‐Cell Grade Hydrogen and Formate: Mechanism and Applications

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