.png){kind=icon}
.png){kind=icon}
Return
Biochar-based active capping for heavy metal-contaminated sediments: mechanistic evaluation and diffusion-adsorption modeling of long-term performance
.png){kind=icon}
PRE
AI
Y
M
C
W
X
Y
X
H
H
DOI：10.1007/s11368-026-04496-2.png)
.png){kind=icon}
Original request for help.png){kind=icon}
Share.png){kind=icon}
Save
Abstract
En 中文
Traditional physical capping often fails to prevent the long-term release of dissolved heavy metals from contaminated sediments. While biochar-based active capping offers a sustainable alternative, its long-term effectiveness and saturation limits remain insufficiently explored. This study aims to evaluate two agricultural biochars as active caps and develop a predictive diffusion model to assess their long-term capacity to suppress Cu, Pb, and Zn release. Laboratory column and diffusion experiments were conducted to compare the immobilization performance of palm wood-chip biochar (MX), straw-stalk biochar (JG), and conventional quartz sand caps over contaminated sediments. Heavy metal concentrations in both sediments and overlying water were monitored. To address the critical gap in long-term performance assessment, a diffusion-adsorption model, grounded in Fick’s second law, was developed. This model integrated experimental adsorption behaviors to simulate transport mechanisms through the active capping layers and predict the long-term performance of the capping strategies. Both biochars markedly inhibited the vertical diffusion of heavy metals, demonstrating consistently superior performance compared to conventional quartz sand. Notably, the migration of Pb was effectively inhibited by the biochar caps, indicating a robust immobilization capacity. The calibrated diffusion-adsorption model successfully elucidated the transport mechanisms, allowing for the prediction of long-term cap performance. Model predictions indicated that, under the tested conditions, a 4-cm-thick JG cap would be penetrated by Cu after approximately 3 years and by Zn after 7 years, highlighting differences in contaminant mobility. The study demonstrates that palm and straw biochars are effective in-situ capping materials for arresting heavy metal migration from sediments. The findings provide a mechanistic framework and practical modeling tools for designing biochar caps. Future applications should consider the predicted breakthrough timelines to ensure the long-term stability and success of sediment remediation strategies.
Keywords:
Capping treatment
Metal contaminated sediment
Biochar
Modeling
Journal
IF:
3
Papers:
548
Citations:
1.1W
Organization
Cited Papers