Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates

Salma Bougarrani; Preetam Sharma; Jeremy Hamilton; Anukriti Singh; Moises Canle; Mohammed El Azzouzi; John Byrne

doi:10.3390/nano10050896

Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates

Salma Bougarrani, Preetam Sharma, Jeremy Hamilton, Anukriti Singh, Moises Canle, Mohammed El Azzouzi, John Byrne

Research output: Contribution to journal › Article › peer-review

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Abstract

The determination of reaction pathways and identification of products of pollutants degradation is central to photocatalytic environmental remediation. This work focuses on the photocatalytic degradation of the herbicide Imazapyr (2-(4-methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl) pyridine-3-carboxylic acid) under UV-Vis and visible-only irradiation of aqueous suspensions of CaxMnOy-TiO2, and on the identification of the corresponding degradation pathways and reaction intermediates. CaxMnOy-TiO2 was formed by mixing CaxMnOy and TiO2 by mechanical grinding followed by annealing at 500 °C. A complete structural characterization of CaxMnOy-TiO2 was carried out. The photocatalytic activity of the hetero-nanostructures was determined using phenol and Imazapyr herbicide as model pollutants in a stirred tank reactor under UV-Vis and visible-only irradiation. Using equivalent loadings, CaxMnOy-TiO2 showed a higher rate (10.6 μM·h−1) as compared to unmodified TiO2 (7.4 μM·h−1) for Imazapyr degradation under UV-Vis irradiation. The mineralization rate was 4.07 µM·h−1 for CaxMnOy-TiO2 and 1.21 μM·h−1 for TiO2. In the CaxMnOy-TiO2 system, the concentration of intermediate products reached a maximum at 180 min of irradiation that then decreased to a half in 120 min. For unmodified TiO2, the intermediates continuously increased with irradiation time with no decrease observed in their concentration. The enhanced efficiency of the CaxMnOy-TiO2 for the complete degradation of the Imazapyr and intermediates is attributed to an increased adsorption of polar species on the surface of CaxMnOy. Based on LC-MS, photocatalytic degradation pathways for Imazapyr under UV-Vis irradiation have been proposed. Some photocatalytic degradation was obtained under visible-only irradiation for CaxMnOy-TiO2. Hydroxyl radicals were found to be main reactive oxygen species responsible for the photocatalytic degradation through radical scavenger investigations.

Original language	English
Article number	896
Pages (from-to)	1-22
Number of pages	22
Journal	Nanomaterials
Volume	10
Issue number	5
DOIs	https://doi.org/10.3390/nano10050896
Publication status	Published (in print/issue) - 8 May 2020

Bibliographical note

Funding Information:
Funding: This research received external funding from the British Council under the STREAM-MENA Institutional Links Scheme Grant number 278072873. This is a collaboration between Ulster University (UK), Technion Institute (Israel) and Rabat University (Morocco). MC acknowledges support from Ministerio de Economía y Competitividad (Spain) through project CTQ2015-71238-R (MINECO/FEDER). AS would like to acknowledge the financial support received from Ulster University (UK) through the VCRS scholarship. PS would like to acknowledge funding from Invest Northern Ireland for the BioDevices project.

Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

persistent organic pollutants
photocatalysis
TiO2
Birnessite
water remediation
hydroxyl radicals
degradation pathways
photoproducts

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10.3390/nano10050896Licence: CC BY

Bougarrani_Nanomaterials 2020Final published version, 8.55 MBLicence: CC BY

Cite this

Bougarrani, S., Sharma, P., Hamilton, J., Singh, A., Canle, M., El Azzouzi, M., & Byrne, J. (2020). Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates. Nanomaterials, 10(5), 1-22. Article 896. https://doi.org/10.3390/nano10050896

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title = "Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates",

abstract = "The determination of reaction pathways and identification of products of pollutants degradation is central to photocatalytic environmental remediation. This work focuses on the photocatalytic degradation of the herbicide Imazapyr (2-(4-methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl) pyridine-3-carboxylic acid) under UV-Vis and visible-only irradiation of aqueous suspensions of CaxMnOy-TiO2, and on the identification of the corresponding degradation pathways and reaction intermediates. CaxMnOy-TiO2 was formed by mixing CaxMnOy and TiO2 by mechanical grinding followed by annealing at 500 °C. A complete structural characterization of CaxMnOy-TiO2 was carried out. The photocatalytic activity of the hetero-nanostructures was determined using phenol and Imazapyr herbicide as model pollutants in a stirred tank reactor under UV-Vis and visible-only irradiation. Using equivalent loadings, CaxMnOy-TiO2 showed a higher rate (10.6 μM·h−1) as compared to unmodified TiO2 (7.4 μM·h−1) for Imazapyr degradation under UV-Vis irradiation. The mineralization rate was 4.07 µM·h−1 for CaxMnOy-TiO2 and 1.21 μM·h−1 for TiO2. In the CaxMnOy-TiO2 system, the concentration of intermediate products reached a maximum at 180 min of irradiation that then decreased to a half in 120 min. For unmodified TiO2, the intermediates continuously increased with irradiation time with no decrease observed in their concentration. The enhanced efficiency of the CaxMnOy-TiO2 for the complete degradation of the Imazapyr and intermediates is attributed to an increased adsorption of polar species on the surface of CaxMnOy. Based on LC-MS, photocatalytic degradation pathways for Imazapyr under UV-Vis irradiation have been proposed. Some photocatalytic degradation was obtained under visible-only irradiation for CaxMnOy-TiO2. Hydroxyl radicals were found to be main reactive oxygen species responsible for the photocatalytic degradation through radical scavenger investigations.",

keywords = "persistent organic pollutants, photocatalysis, TiO2, Birnessite, water remediation, hydroxyl radicals, degradation pathways, photoproducts",

author = "Salma Bougarrani and Preetam Sharma and Jeremy Hamilton and Anukriti Singh and Moises Canle and {El Azzouzi}, Mohammed and John Byrne",

note = "Funding Information: Funding: This research received external funding from the British Council under the STREAM-MENA Institutional Links Scheme Grant number 278072873. This is a collaboration between Ulster University (UK), Technion Institute (Israel) and Rabat University (Morocco). MC acknowledges support from Ministerio de Econom{\'i}a y Competitividad (Spain) through project CTQ2015-71238-R (MINECO/FEDER). AS would like to acknowledge the financial support received from Ulster University (UK) through the VCRS scholarship. PS would like to acknowledge funding from Invest Northern Ireland for the BioDevices project. Publisher Copyright: {\textcopyright} 2020 by the authors. Licensee MDPI, Basel, Switzerland. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.",

year = "2020",

month = may,

day = "8",

doi = "10.3390/nano10050896",

language = "English",

volume = "10",

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Bougarrani, S, Sharma, P, Hamilton, J, Singh, A, Canle, M, El Azzouzi, M & Byrne, J 2020, 'Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates', Nanomaterials, vol. 10, no. 5, 896, pp. 1-22. https://doi.org/10.3390/nano10050896

Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates. / Bougarrani, Salma; Sharma, Preetam; Hamilton, Jeremy et al.
In: Nanomaterials, Vol. 10, No. 5, 896, 08.05.2020, p. 1-22.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates

AU - Bougarrani, Salma

AU - Sharma, Preetam

AU - Hamilton, Jeremy

AU - Singh, Anukriti

AU - Canle, Moises

AU - El Azzouzi, Mohammed

AU - Byrne, John

N1 - Funding Information: Funding: This research received external funding from the British Council under the STREAM-MENA Institutional Links Scheme Grant number 278072873. This is a collaboration between Ulster University (UK), Technion Institute (Israel) and Rabat University (Morocco). MC acknowledges support from Ministerio de Economía y Competitividad (Spain) through project CTQ2015-71238-R (MINECO/FEDER). AS would like to acknowledge the financial support received from Ulster University (UK) through the VCRS scholarship. PS would like to acknowledge funding from Invest Northern Ireland for the BioDevices project. Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/5/8

Y1 - 2020/5/8

N2 - The determination of reaction pathways and identification of products of pollutants degradation is central to photocatalytic environmental remediation. This work focuses on the photocatalytic degradation of the herbicide Imazapyr (2-(4-methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl) pyridine-3-carboxylic acid) under UV-Vis and visible-only irradiation of aqueous suspensions of CaxMnOy-TiO2, and on the identification of the corresponding degradation pathways and reaction intermediates. CaxMnOy-TiO2 was formed by mixing CaxMnOy and TiO2 by mechanical grinding followed by annealing at 500 °C. A complete structural characterization of CaxMnOy-TiO2 was carried out. The photocatalytic activity of the hetero-nanostructures was determined using phenol and Imazapyr herbicide as model pollutants in a stirred tank reactor under UV-Vis and visible-only irradiation. Using equivalent loadings, CaxMnOy-TiO2 showed a higher rate (10.6 μM·h−1) as compared to unmodified TiO2 (7.4 μM·h−1) for Imazapyr degradation under UV-Vis irradiation. The mineralization rate was 4.07 µM·h−1 for CaxMnOy-TiO2 and 1.21 μM·h−1 for TiO2. In the CaxMnOy-TiO2 system, the concentration of intermediate products reached a maximum at 180 min of irradiation that then decreased to a half in 120 min. For unmodified TiO2, the intermediates continuously increased with irradiation time with no decrease observed in their concentration. The enhanced efficiency of the CaxMnOy-TiO2 for the complete degradation of the Imazapyr and intermediates is attributed to an increased adsorption of polar species on the surface of CaxMnOy. Based on LC-MS, photocatalytic degradation pathways for Imazapyr under UV-Vis irradiation have been proposed. Some photocatalytic degradation was obtained under visible-only irradiation for CaxMnOy-TiO2. Hydroxyl radicals were found to be main reactive oxygen species responsible for the photocatalytic degradation through radical scavenger investigations.

AB - The determination of reaction pathways and identification of products of pollutants degradation is central to photocatalytic environmental remediation. This work focuses on the photocatalytic degradation of the herbicide Imazapyr (2-(4-methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl) pyridine-3-carboxylic acid) under UV-Vis and visible-only irradiation of aqueous suspensions of CaxMnOy-TiO2, and on the identification of the corresponding degradation pathways and reaction intermediates. CaxMnOy-TiO2 was formed by mixing CaxMnOy and TiO2 by mechanical grinding followed by annealing at 500 °C. A complete structural characterization of CaxMnOy-TiO2 was carried out. The photocatalytic activity of the hetero-nanostructures was determined using phenol and Imazapyr herbicide as model pollutants in a stirred tank reactor under UV-Vis and visible-only irradiation. Using equivalent loadings, CaxMnOy-TiO2 showed a higher rate (10.6 μM·h−1) as compared to unmodified TiO2 (7.4 μM·h−1) for Imazapyr degradation under UV-Vis irradiation. The mineralization rate was 4.07 µM·h−1 for CaxMnOy-TiO2 and 1.21 μM·h−1 for TiO2. In the CaxMnOy-TiO2 system, the concentration of intermediate products reached a maximum at 180 min of irradiation that then decreased to a half in 120 min. For unmodified TiO2, the intermediates continuously increased with irradiation time with no decrease observed in their concentration. The enhanced efficiency of the CaxMnOy-TiO2 for the complete degradation of the Imazapyr and intermediates is attributed to an increased adsorption of polar species on the surface of CaxMnOy. Based on LC-MS, photocatalytic degradation pathways for Imazapyr under UV-Vis irradiation have been proposed. Some photocatalytic degradation was obtained under visible-only irradiation for CaxMnOy-TiO2. Hydroxyl radicals were found to be main reactive oxygen species responsible for the photocatalytic degradation through radical scavenger investigations.

KW - persistent organic pollutants

KW - photocatalysis

KW - TiO2

KW - Birnessite

KW - water remediation

KW - hydroxyl radicals

KW - degradation pathways

KW - photoproducts

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U2 - 10.3390/nano10050896

DO - 10.3390/nano10050896

M3 - Article

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SN - 2079-4991

VL - 10

SP - 1

EP - 22

JO - Nanomaterials

JF - Nanomaterials

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M1 - 896

ER -

Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of CaxMnOy-TiO2 Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates

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