Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals
Recently, the activation of chlorine dioxide (ClO<sub>2</sub>) by metal(oxide) for soil remediation has gained notable attention. However, the related activation mechanisms are still not clear. Herein, the variation of iron species and ClO<sub>2</sub>, the generated reactive...
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2025-01-01
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| author | Xiaojun Hu Xiaorong Xing Fan Zhang Bingzhi Li Senlin Chen Bo Wang Jiaolong Qin Jie Miao |
| author_facet | Xiaojun Hu Xiaorong Xing Fan Zhang Bingzhi Li Senlin Chen Bo Wang Jiaolong Qin Jie Miao |
| author_sort | Xiaojun Hu |
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| description | Recently, the activation of chlorine dioxide (ClO<sub>2</sub>) by metal(oxide) for soil remediation has gained notable attention. However, the related activation mechanisms are still not clear. Herein, the variation of iron species and ClO<sub>2</sub>, the generated reactive oxygen species, and the toxicity of the degradation intermediates were explored and evaluated with nanoscale zero-valent iron (nFe<sup>0</sup>) being employed to activate ClO<sub>2</sub> for soil polycyclic aromatic hydrocarbon (PAH) removal. With an optimized ClO<sub>2</sub>/nFe<sup>0</sup> molar ratio of 15:1 and a soil/water ratio of 3:1, the degradation efficiency of phenanthrene improved 12% in comparison with that of a ClO<sub>2</sub>-alone system. The presence of nFe<sup>0</sup> significantly promoted ClO<sub>2</sub> consumption (improved 85.4%) but restrained ClO<sub>2</sub><sup>−</sup> generation (reduced 22.5%). The surface Fe(II) and soluble Fe(II) in the ClO<sub>2</sub>/nFe<sup>0</sup> system was 2.0-fold and 2.8-fold that in the nFe<sup>0</sup> system after 2 min. Electron paramagnetic resonance analysis, along with quenching experiments, revealed that Fe(IV), HOCl, and •OH dominated phenanthrene degradation in a ClO<sub>2</sub>/nFe<sup>0</sup> system, with oxidation contributions, respectively, of 34.3%, 52.8% and 12.9%. The degradation intermediates of PAHs in the ClO<sub>2</sub>/nFe<sup>0</sup> system had lower estimated toxicity than those of the ClO<sub>2</sub> system. The lettuces grown in ClO<sub>2</sub>/nFe<sup>0</sup>-treated soil displayed better results in bioassay indexes than those grown in ClO<sub>2</sub>-treated soil. This study offers new perspectives for the remediation of organic-pollutant-contaminated soil by using metal-activated ClO<sub>2</sub> technology. |
| format | Article |
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| institution | Kabale University |
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| spelling | doaj-art-23c2ff7ec1d14a72b97959a7a43a26e42025-01-24T13:51:01ZengMDPI AGToxics2305-63042025-01-011313610.3390/toxics13010036Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl RadicalsXiaojun Hu0Xiaorong Xing1Fan Zhang2Bingzhi Li3Senlin Chen4Bo Wang5Jiaolong Qin6Jie Miao7School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, ChinaSchool of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, ChinaRecently, the activation of chlorine dioxide (ClO<sub>2</sub>) by metal(oxide) for soil remediation has gained notable attention. However, the related activation mechanisms are still not clear. Herein, the variation of iron species and ClO<sub>2</sub>, the generated reactive oxygen species, and the toxicity of the degradation intermediates were explored and evaluated with nanoscale zero-valent iron (nFe<sup>0</sup>) being employed to activate ClO<sub>2</sub> for soil polycyclic aromatic hydrocarbon (PAH) removal. With an optimized ClO<sub>2</sub>/nFe<sup>0</sup> molar ratio of 15:1 and a soil/water ratio of 3:1, the degradation efficiency of phenanthrene improved 12% in comparison with that of a ClO<sub>2</sub>-alone system. The presence of nFe<sup>0</sup> significantly promoted ClO<sub>2</sub> consumption (improved 85.4%) but restrained ClO<sub>2</sub><sup>−</sup> generation (reduced 22.5%). The surface Fe(II) and soluble Fe(II) in the ClO<sub>2</sub>/nFe<sup>0</sup> system was 2.0-fold and 2.8-fold that in the nFe<sup>0</sup> system after 2 min. Electron paramagnetic resonance analysis, along with quenching experiments, revealed that Fe(IV), HOCl, and •OH dominated phenanthrene degradation in a ClO<sub>2</sub>/nFe<sup>0</sup> system, with oxidation contributions, respectively, of 34.3%, 52.8% and 12.9%. The degradation intermediates of PAHs in the ClO<sub>2</sub>/nFe<sup>0</sup> system had lower estimated toxicity than those of the ClO<sub>2</sub> system. The lettuces grown in ClO<sub>2</sub>/nFe<sup>0</sup>-treated soil displayed better results in bioassay indexes than those grown in ClO<sub>2</sub>-treated soil. This study offers new perspectives for the remediation of organic-pollutant-contaminated soil by using metal-activated ClO<sub>2</sub> technology.https://www.mdpi.com/2305-6304/13/1/36Fe(IV)hydroxyl radicalspolycyclic aromatic hydrocarbonschlorine dioxidenanoscale zero-valent iron |
| spellingShingle | Xiaojun Hu Xiaorong Xing Fan Zhang Bingzhi Li Senlin Chen Bo Wang Jiaolong Qin Jie Miao Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals Toxics Fe(IV) hydroxyl radicals polycyclic aromatic hydrocarbons chlorine dioxide nanoscale zero-valent iron |
| title | Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals |
| title_full | Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals |
| title_fullStr | Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals |
| title_full_unstemmed | Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals |
| title_short | Activation of ClO<sub>2</sub> by Nanoscale Zero-Valent Iron for Efficient Soil Polycyclic Aromatic Hydrocarbon Degradation: New Insight into the Relative Contribution of Fe(IV) and Hydroxyl Radicals |
| title_sort | activation of clo sub 2 sub by nanoscale zero valent iron for efficient soil polycyclic aromatic hydrocarbon degradation new insight into the relative contribution of fe iv and hydroxyl radicals |
| topic | Fe(IV) hydroxyl radicals polycyclic aromatic hydrocarbons chlorine dioxide nanoscale zero-valent iron |
| url | https://www.mdpi.com/2305-6304/13/1/36 |
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