Release characteristics of biochar-derived dissolved organic matter and its impact on Cr() adsorption and reduction

Biochar has received widespread attention as a promising amendment for heavy metal stabilization due to its abundant porosity and surface functional groups. However, the role of biochar-derived dissolved organic matter (BDOM) is usually overlooked. In this study, we systematically investigated the l...

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Bibliographic Details
Published in:RSC advances 2024-11, Vol.14 (51), p.38171-38182
Main Authors: Liu, Hui, Wang, Ying, Wang, Shixu, Wu, Jing, Wang, Yulai
Format: Article
Language:English
Subjects:
Adsorption
Chemistry
Contaminated land
Dissolved organic matter
Extreme values
Functional groups
Heavy metals
Iron
Leaching
Oxidation
Pyrolysis
Soil porosity
Soil remediation
Stabilization
Wastes
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Summary:Biochar has received widespread attention as a promising amendment for heavy metal stabilization due to its abundant porosity and surface functional groups. However, the role of biochar-derived dissolved organic matter (BDOM) is usually overlooked. In this study, we systematically investigated the leaching dynamics of BDOM from garden wastes through hydrothermal carbonization (HC), pyrolysis (PC) and hydro/pyrolysis (HPC) and explored their impacts on Cr( vi ) environmental behavior in an extremely acidic environment. Results showed that BDOM leaching dynamics followed the first order model, and HC leached more BDOM than PC and HPC, especially for Ar-P, SMP and Ha-L fractions. Although carbonized using various methods, the biochars displayed a similar adsorption capacity for Cr( vi ) at an environmental-related concentration of 2 mg L −1 . The presence of BDOM accelerated the Cr( vi ) adsorption rate on biochars due to their pre-complexing. Simultaneously, HC-BDOM acted as an electron donor and participate in Cr( vi ) reduction directly, resulting in the synchronous reduction of Cr( vi ) during its adsorption process. However, PC- and HPC-BDOM preferentially acted as electron acceptors, thus competing with Cr( vi ) for Fe( ii ) oxidation and decreased the Cr( vi ) reduction rate. This study suggested that biochar from garden wastes has a great remediation potential for Cr-contaminated land and that BDOM (especially HC-BDOM) plays a significant role in increasing soil organic matter, stabilizing heavy metals and detoxifying toxic substances by oxidation-reduction. The roles of biochar-derived dissolved organic matter in the remediation of Cr-contaminated soil after biochar amendment in practice.
ISSN:2046-2069
2046-2069
DOI:10.1039/d4ra06172a