Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates
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-carboxyl...
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doaj-f37f5fd174dc40d292200c4bd92a5dbb2020-11-25T02:01:02ZengMDPI AGNanomaterials2079-49912020-05-011089689610.3390/nano10050896Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction IntermediatesSalma Bougarrani0Preetam K. Sharma1Jeremy W. J. Hamilton2Anukriti Singh3Moisés Canle4Mohammed El Azzouzi5John Anthony Byrne6Laboratory of Spectroscopy, Molecular Modelling, Materials, Nanomaterials, Water and Environment, University Med V, Avenue Ibn Battouta, B.P. 1014 Rabat, MoroccoNIBEC, Ulster University, Newtownabbey BT37 0QB, UKNIBEC, Ulster University, Newtownabbey BT37 0QB, UKNIBEC, Ulster University, Newtownabbey BT37 0QB, UKChemical Reactivity and Photoreactivity Group, Department of Chemistry, Faculty of Sciences & CICA, University of A Coruña, E-15071 A Coruña, SpainLaboratory of Spectroscopy, Molecular Modelling, Materials, Nanomaterials, Water and Environment, University Med V, Avenue Ibn Battouta, B.P. 1014 Rabat, MoroccoNIBEC, Ulster University, Newtownabbey BT37 0QB, UKThe 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 Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub>, and on the identification of the corresponding degradation pathways and reaction intermediates. Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> was formed by mixing Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i> and TiO<sub>2</sub> by mechanical grinding followed by annealing at 500 °C. A complete structural characterization of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> 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, Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> showed a higher rate (10.6 μM·h<sup>−1</sup>) as compared to unmodified TiO<sub>2</sub> (7.4 μM·h<sup>−1</sup>) for Imazapyr degradation under UV-Vis irradiation. The mineralization rate was 4.07 µM·h<sup>−1</sup> for Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> and 1.21 μM·h<sup>−1</sup> for TiO<sub>2</sub>. In the Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> 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 TiO<sub>2</sub>, the intermediates continuously increased with irradiation time with no decrease observed in their concentration. The enhanced efficiency of the Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> for the complete degradation of the Imazapyr and intermediates is attributed to an increased adsorption of polar species on the surface of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>. 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 Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub>. Hydroxyl radicals were found to be main reactive oxygen species responsible for the photocatalytic degradation through radical scavenger investigations.https://www.mdpi.com/2079-4991/10/5/896persistent organic pollutantsphotocatalysisTiO<sub>2</sub>birnessitewater remediationhydroxyl radicals |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Salma Bougarrani Preetam K. Sharma Jeremy W. J. Hamilton Anukriti Singh Moisés Canle Mohammed El Azzouzi John Anthony Byrne |
spellingShingle |
Salma Bougarrani Preetam K. Sharma Jeremy W. J. Hamilton Anukriti Singh Moisés Canle Mohammed El Azzouzi John Anthony Byrne Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates Nanomaterials persistent organic pollutants photocatalysis TiO<sub>2</sub> birnessite water remediation hydroxyl radicals |
author_facet |
Salma Bougarrani Preetam K. Sharma Jeremy W. J. Hamilton Anukriti Singh Moisés Canle Mohammed El Azzouzi John Anthony Byrne |
author_sort |
Salma Bougarrani |
title |
Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates |
title_short |
Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates |
title_full |
Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates |
title_fullStr |
Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates |
title_full_unstemmed |
Enhanced Photocatalytic Degradation of the Imidazolinone Herbicide Imazapyr upon UV/Vis Irradiation in the Presence of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> Hetero-Nanostructures: Degradation Pathways and Reaction Intermediates |
title_sort |
enhanced photocatalytic degradation of the imidazolinone herbicide imazapyr upon uv/vis irradiation in the presence of ca<i><sub>x</sub></i>mno<i><sub>y</sub></i>-tio<sub>2</sub> hetero-nanostructures: degradation pathways and reaction intermediates |
publisher |
MDPI AG |
series |
Nanomaterials |
issn |
2079-4991 |
publishDate |
2020-05-01 |
description |
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 Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub>, and on the identification of the corresponding degradation pathways and reaction intermediates. Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> was formed by mixing Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i> and TiO<sub>2</sub> by mechanical grinding followed by annealing at 500 °C. A complete structural characterization of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> 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, Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> showed a higher rate (10.6 μM·h<sup>−1</sup>) as compared to unmodified TiO<sub>2</sub> (7.4 μM·h<sup>−1</sup>) for Imazapyr degradation under UV-Vis irradiation. The mineralization rate was 4.07 µM·h<sup>−1</sup> for Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> and 1.21 μM·h<sup>−1</sup> for TiO<sub>2</sub>. In the Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> 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 TiO<sub>2</sub>, the intermediates continuously increased with irradiation time with no decrease observed in their concentration. The enhanced efficiency of the Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub> for the complete degradation of the Imazapyr and intermediates is attributed to an increased adsorption of polar species on the surface of Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>. 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 Ca<i><sub>x</sub></i>MnO<i><sub>y</sub></i>-TiO<sub>2</sub>. Hydroxyl radicals were found to be main reactive oxygen species responsible for the photocatalytic degradation through radical scavenger investigations. |
topic |
persistent organic pollutants photocatalysis TiO<sub>2</sub> birnessite water remediation hydroxyl radicals |
url |
https://www.mdpi.com/2079-4991/10/5/896 |
work_keys_str_mv |
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