Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in arid/semi-arid soils, and their hydrophobicity and bioaccumulation pose significant threats to ecosystems and human health. Conventional remediation techniques such as advanced oxidation, are limited by high costs and secondary contam...

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Main Authors: Pengfei Cheng, Haoli Qin, Junxia Cheng, Junliang Chen, ManMan Yu, Zhiliang Li, Yao Lu, Guanlin Li, Daolin Du
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Applied Catalysis O: Open
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Online Access:http://www.sciencedirect.com/science/article/pii/S2950648425000227
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author Pengfei Cheng
Haoli Qin
Junxia Cheng
Junliang Chen
ManMan Yu
Zhiliang Li
Yao Lu
Guanlin Li
Daolin Du
author_facet Pengfei Cheng
Haoli Qin
Junxia Cheng
Junliang Chen
ManMan Yu
Zhiliang Li
Yao Lu
Guanlin Li
Daolin Du
author_sort Pengfei Cheng
collection DOAJ
description Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in arid/semi-arid soils, and their hydrophobicity and bioaccumulation pose significant threats to ecosystems and human health. Conventional remediation techniques such as advanced oxidation, are limited by high costs and secondary contamination risks, driving the need for efficient and eco-friendly in-situ methods. In this study, the activity of biochar derived from invasive plant Wedelia trilobata (pyrolyzed at 400, 600, and 800 °C; BC400/600/800) were assessed by BET, XPS, CV, and EPR. The efficacy of biochar-mineral (goethite, hematite, magnetite, birnessite, cryptomelane, montmorillonite, and kaolinite) composites for PAHs degradation performance and the mechanisms were studied. BC800 was optimal for benzo(a)pyrene (BaP) degradation (rate constant: 0.0360 min−1), attributable to its high specific surface area (301.44 m2/g), abundant oxygen-containing functional groups (CO, CO), and electron transfer capacity. The degradation rates were positively correlated with the highest occupied molecular orbital (HOMO) levels of the PAHs (R2 = 0.6850), confirming dominant electron transfer. Among seven mineral composites, the Bir-biochar combination enhanced BaP degradation by 2.3-fold through the “electron shuttle” function of the Mn(IV)/Mn(III) redox couples. In a dry system, as the moisture increased, the degradation efficiency also increased. This study elucidates the adsorption-electron transfer mechanism of biochar-mineral composites for PAHs degradation in arid environments, providing a theoretical foundation and technical support for utilizing invasive plants utilization and remediating dryland soils polluted with organic species.
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spelling doaj-art-cd85d87a6bbf4edfbeb40b643c5d52ec2025-08-20T03:48:31ZengElsevierApplied Catalysis O: Open2950-64842025-06-0120320704710.1016/j.apcato.2025.207047Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry systemPengfei Cheng0Haoli Qin1Junxia Cheng2Junliang Chen3ManMan Yu4Zhiliang Li5Yao Lu6Guanlin Li7Daolin Du8School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, ChinaSchool of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001, ChinaChemical Engineering College, University of Science and Technology Liaoning, Anshan 114051, ChinaSchool of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, ChinaSchool of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, ChinaSchool of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, ChinaSchool of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, ChinaSchool of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China; Corresponding authors.Jingjiang College, Jiangsu University, Zhenjiang 212013, China; Corresponding authors.Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in arid/semi-arid soils, and their hydrophobicity and bioaccumulation pose significant threats to ecosystems and human health. Conventional remediation techniques such as advanced oxidation, are limited by high costs and secondary contamination risks, driving the need for efficient and eco-friendly in-situ methods. In this study, the activity of biochar derived from invasive plant Wedelia trilobata (pyrolyzed at 400, 600, and 800 °C; BC400/600/800) were assessed by BET, XPS, CV, and EPR. The efficacy of biochar-mineral (goethite, hematite, magnetite, birnessite, cryptomelane, montmorillonite, and kaolinite) composites for PAHs degradation performance and the mechanisms were studied. BC800 was optimal for benzo(a)pyrene (BaP) degradation (rate constant: 0.0360 min−1), attributable to its high specific surface area (301.44 m2/g), abundant oxygen-containing functional groups (CO, CO), and electron transfer capacity. The degradation rates were positively correlated with the highest occupied molecular orbital (HOMO) levels of the PAHs (R2 = 0.6850), confirming dominant electron transfer. Among seven mineral composites, the Bir-biochar combination enhanced BaP degradation by 2.3-fold through the “electron shuttle” function of the Mn(IV)/Mn(III) redox couples. In a dry system, as the moisture increased, the degradation efficiency also increased. This study elucidates the adsorption-electron transfer mechanism of biochar-mineral composites for PAHs degradation in arid environments, providing a theoretical foundation and technical support for utilizing invasive plants utilization and remediating dryland soils polluted with organic species.http://www.sciencedirect.com/science/article/pii/S2950648425000227BiocharBiochar-mineral compositesPolycyclic aromatic hydrocarbonsDegradation
spellingShingle Pengfei Cheng
Haoli Qin
Junxia Cheng
Junliang Chen
ManMan Yu
Zhiliang Li
Yao Lu
Guanlin Li
Daolin Du
Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system
Applied Catalysis O: Open
Biochar
Biochar-mineral composites
Polycyclic aromatic hydrocarbons
Degradation
title Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system
title_full Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system
title_fullStr Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system
title_full_unstemmed Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system
title_short Mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar-mineral composites in the dry system
title_sort mechanisms of degradation of polycyclic aromatic hydrocarbons by biochar and biochar mineral composites in the dry system
topic Biochar
Biochar-mineral composites
Polycyclic aromatic hydrocarbons
Degradation
url http://www.sciencedirect.com/science/article/pii/S2950648425000227
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