- Extending the lifetime of organic flow batteries via redox state management
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Redox flow batteries based on quinonebearing aqueous electrolytes have emerged as promising systems for energy storage from intermittent renewable sources. The lifetime of these batteries is limited by quinone stability. Here, we confirm that 2,6-dihydroxyanthrahydroquinone tends to form an anthrone intermediate that is vulnerable to subsequent irreversible dimerization. We demonstrate quantitatively that this decomposition pathway is responsible for the loss of battery capacity. Computational studies indicate that the driving force for anthrone formation is greater for anthraquinones with lower reduction potentials. We show that the decomposition can be substantially mitigated. We demonstrate that conditions minimizing anthrone formation and avoiding anthrone dimerization slow the capacity loss rate by over an order of magnitude. We anticipate that this mitigation strategy readily extends to other anthraquinone-based flow batteries and is thus an important step toward realizing renewable electricity storage through long-lived organic flow batteries.
- Goulet, Marc-Antoni,Tong, Liuchuan,Pollack, Daniel A.,Tabor, Daniel P.,Odom, Susan A.,Aspuru-Guzik, Alán,Kwan, Eugene E.,Gordon, Roy G.,Aziz, Michael J.
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- Pathway of anthracene modification under simulated solar radiation
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Exposure of polycyclic aromatic hydrocarbons (PAHs) to sunlight results in rapid structural photomodification generally via oxidation reactions. These PAH modification products are in many cases more toxic than their parent compounds. In this study, anthracene (ANT), a rapidly photooxidized PAH, was irradiated with simulated solar radiation (SSR, 100 μmol m-2 s- 1) in aqueous solution to examine the photomodification pathway. The photoproducts formed were identified by HPLC. The ANT product profile after 9 h in SSR was very complex, with more than 20 compounds detected. The photoproducts formed were anthraquinones, benzoic acids, benzaldehydes and phenols showing the process to be oxidative in nature. Some of the anthraquinones were themselves subject to photooxidation, and were thus intermediates in the product pathway. The kinetics of ANT photooxidation revealed a pseudo first-order reaction with a half-life of 2 h under the SSR source used. The kinetics of product formation allowed deduction of a probable photomodification pathway. This study indicates that PAH photooxidation products are likely to exist as complex, dynamically changing mixtures in PAH contaminated aquatic environments.
- Mallakin, Ali,George Dixon,Greenberg, Bruce M.
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p. 1435 - 1441
(2007/10/03)
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- Method for dyeing keratinous fibres using a monohydroxyindole or dihydroxyindole and a non-oxidizing aromatic carbonyl derivative and dyeing agent
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The present invention relates to a method for dyeing keratinous fibers, characterized in that the following are applied to the fibers: a) a composition (A) containing, in a medium appropriate for dyeing, at least one monohydroxyindole or dihydroxyindole, this application being preceded or followed by the application of b) a composition (B) containing, in a medium appropriate for dyeing, at least one aromatic carbonyl derivative chosen from hydroxyacetophenones, hydroxybenzophenones, 2-hydroxy-1,4-benzoquinones, hydroxy-1,4-naphthoquinones,amino-1,4-naphthoquinones,hydroxy-9,10-anthraquinones and amino-9,10-anthraquinones. It also relates to the dyeing agents for carrying it out.
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