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Enhanced transformation capability towards benzo(a)pyrene by Fe(III)-modified manganese oxides
Pengfei Cheng1, Zhipeng Lin1, Xuqiang Zhao1
1Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Journal of Hazardous Materials
|March 12, 2022
Summary
Iron(III) modification significantly enhances manganese oxides' ability to transform benzo(a)pyrene, a harmful pollutant. This finding is crucial for understanding and improving the removal of polycyclic aromatic hydrocarbons (PAHs) in soils.
Area of Science:
- Environmental Chemistry
- Geochemistry
- Soil Science
Background:
- Manganese oxides (Mn oxides) are common in soils and can interact with iron(III) ions.
- Benzo(a)pyrene is a persistent organic pollutant found in soil environments.
- Understanding the transformation pathways of benzo(a)pyrene in soil is critical for environmental remediation.
Purpose of the Study:
- To investigate the effect of Fe(III) modification on the benzo(a)pyrene transformation capability of various Mn oxides.
- To elucidate the mechanisms behind the enhanced transformation of benzo(a)pyrene by Fe(III)-modified Mn oxides.
- To assess the environmental implications of Fe(III) presence on polycyclic aromatic hydrocarbon (PAH) fate in soils.
Main Methods:
- Synthesis of various Mn oxides (acid birnessite, alkaline birnessite, cryptomelane, pyrolusite, manganite) and their Fe(III)-modified analogues.
- Quantification of benzo(a)pyrene transformation rates using kinetic studies.
- Analysis of surface properties, including adsorbed water, oxygen, and active free radicals.
- Characterization of transformation products' physicochemical and biochemical properties.
Main Results:
- Fe(III)-modified Mn oxides exhibited significantly enhanced benzo(a)pyrene transformation rates compared to unmodified oxides.
- Fe(III)-modified layered birnessites showed superior activity, attributed to higher Fe(III) content and more active free radicals.
- Fe(III) facilitated electron transfer from benzo(a)pyrene, increased surface adsorbed water and oxygen, and promoted radical generation.
Conclusions:
- The presence of Fe(III) ions substantially promotes the removal of PAHs by Mn oxides in soil environments.
- Fe(III) modification offers a promising strategy for enhancing the degradation of organic pollutants in soils.
- This study provides critical insights into the fate of PAHs in natural soil systems containing Mn oxides and Fe(III).
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