Nitrite ion reduction to ammonia in illuminated aqueous suspensions of powdered semiconductors in alkaline sulphide solutions

Halmann, M.; Zuckerman, K.

doi:10.1039/c39860000455

Cited by 15 publications

(6 citation statements)

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“…The photocatalytic reduction of nitrate has recently received special attention in view of pollution control. − Therefore, it is of particular interest to study the kinetics of these reduction reactions by the stored TiO 2 electrons.…”

Section: Resultsmentioning

confidence: 99%

Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO₂ Nanoparticles: A Stopped Flow Study

et al. 2011

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The kinetics and the mechanism of various multielectron transfer reactions initiated by stored electrons in TiO(2) nanoparticles have been investigated employing the stopped flow technique. Moreover, the optical properties of the stored electrons in the TiO(2) nanoparticles have been studied in detail following the UV (A) photolysis of deaerated aqueous suspensions of TiO(2) nanoparticles in the presence of methanol. The reduction of common electron acceptors that are often present in photocatalytic systems such as O(2), H(2)O(2), and NO(3)(-) has been investigated. The experimental results clearly show that the stored electrons reduce O(2) and H(2)O(2) to water by multielectron transfer processes. Moreover, NO(3)(-) is reduced via the transfer of eight electrons evincing the formation of ammonia. On the other hand, the reduction of toxic metal ions, such as Cu(II), has been studied mixing their respective anoxic aqueous solutions with those containing the electrons stored in the TiO(2) particles. A two-electron transfer is found to occur, indicating the reduction of the copper metal ion into its non toxic metallic form. Other metal ions, such as Zn(II) and Mn(II), could not be reduced by TiO(2) electrons, which is readily explained on the bases of their respective redox potentials. The underlying reaction mechanisms are discussed in detail.

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Section: Resultsmentioning

confidence: 99%

Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO₂ Nanoparticles: A Stopped Flow Study

et al. 2011

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“…Neither nitrate nor nitrite could be reduced to ammonia without the ruthenium promoter. Reduction of nitrite in an aqueous suspension of titania without metal promoters was found to be possible in the presence of sulfide [39]. Nitrite can also be reoxidized to nitrate with oxygen present and with the anatase phase of titania as a photocatalyst as shown by Hori et al [40].…”

Section: Nitrate and Titaniamentioning

confidence: 94%

Photoinduced decomposition of nitrate in drinking water in the presence of titania and humic acids

Bems

Jentoft

Schlögl

1999

Applied Catalysis B: Environmental

108

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The photoreduction of nitrate in aqueous medium was investigated at 292 K in a batch system open to the ambient. Titania was tested as a photocatalyst and humic acids were added as promoters. Conversions of 28% were reached after 80 hours when a 44 mg/l nitrate solution was irradiated with a high pressure Xe-lamp; the major product was nitrite. The addition of humic acids (20 mg/l) promoted reduction of nitrate to nitrite but the mechanism of promotion could not be unambiguously identified. Titania (0.1 g/l) itself did not catalyze the photoreduction of nitrate but rather seemed to act as a catalyst for the reoxidation of nitrite to nitrate. The most successful system was a combination of 44 mg/l nitrate, 20 mg/l humic acids and 0.1 g/l Kronos-1002 titania: the nitrate conversion reached 32% after 76 hours, with little nitrite formed. Photocatalytic nitrate degradation is accompanied by homogeneous reduction to the more toxic nitrite; requiring any effective catalyst system to also reduce nitrite concentration.

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“…A number of photocatalytic materials both doped and undoped; such as TiO 2 , 2,12-17 ZnO, [18][19][20] SrTiO 3 , 21 CdS, [22][23][24] ZnS, 25,26 Fe 2 O 3 , 19,27 and ZrO 2 (ref. 19) have been studied for photocatalytic nitrate reduction to date.…”

Section: Introductionmentioning

confidence: 99%

Microwave synthesised Pd–TiO₂ for photocatalytic ammonia production

2019

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Nitrite ion reduction to ammonia in illuminated aqueous suspensions of powdered semiconductors in alkaline sulphide solutions

Cited by 15 publications

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Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO₂ Nanoparticles: A Stopped Flow Study

Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO₂ Nanoparticles: A Stopped Flow Study

Photoinduced decomposition of nitrate in drinking water in the presence of titania and humic acids

Microwave synthesised Pd–TiO₂ for photocatalytic ammonia production

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Nitrite ion reduction to ammonia in illuminated aqueous suspensions of powdered semiconductors in alkaline sulphide solutions

Cited by 15 publications

References 0 publications

Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO2 Nanoparticles: A Stopped Flow Study

Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO2 Nanoparticles: A Stopped Flow Study

Photoinduced decomposition of nitrate in drinking water in the presence of titania and humic acids

Microwave synthesised Pd–TiO2 for photocatalytic ammonia production

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Product

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Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO₂ Nanoparticles: A Stopped Flow Study

Kinetic and Mechanistic Investigations of Multielectron Transfer Reactions Induced by Stored Electrons in TiO₂ Nanoparticles: A Stopped Flow Study

Microwave synthesised Pd–TiO₂ for photocatalytic ammonia production