Iron, carbon, and the art of toxic cleanup
Researchers at Tongji University unlock the secrets of how low-crystallinity minerals trap chromium and store carbon simultaneously
Biochar Editorial Office, Shenyang Agricultural University
image:
Decomposition of cyanobacteria and submerged macrophytes: impacts on carbon emissions and nutrient cycling in lake ecosystems
view moreCredit: Image Credit：Hanrui Wang, Yanzhi Cui, Jie Ma*, Zhipeng Pei, Guodong Bian, Fei He, Ming Ji* and Xiaoguang Xu
In the complex world of soil and water chemistry, certain minerals act like microscopic sponges, soaking up pollutants and keeping our environment safe. Among the most dangerous of these pollutants is hexavalent chromium—Cr(VI)—a highly toxic and mobile substance often found at industrial and mining sites. Now, a groundbreaking study published in Carbon Research has identified the specific "superstar" minerals that are best at neutralizing this threat while simultaneously locking away organic carbon.
The research, led by Professor Bin Dong from Tongji University, focuses on the interaction between dissolved organic matter (DOM) and various iron (oxyhydr)oxides. The team discovered that low-crystallinity minerals, specifically ferrihydrite, are far more effective at managing chromium than their more "perfect" crystalline cousins like goethite and hematite. This work represents a major collaborative effort centered at the College of Environmental Science and Engineering at Tongji University and the Shanghai Institute of Pollution Control and Ecological Security, with support from the YANGTZE Eco-Environment Engineering Research Center and Guilin University of Technology. "Nature has a built-in filtration system, but not all minerals are created equal," says Professor Bin Dong. "By understanding the molecular handshake between organic matter and iron minerals, we can design smarter, nature-based solutions to clean up heavily contaminated mine soils while helping the planet store more carbon."
The "Ferrihydrite" Advantage:
The study utilized ultra-high-resolution mass spectrometry (FT-ICR MS) and advanced electron microscopy to watch these chemical reactions in real-time. The findings were striking:
- Surface Power: Unlike other minerals where reactions happen in the surrounding water, ferrihydrite pulls both the organic matter and the toxic chromium onto its surface. This "surface-first" approach creates a much faster and more stable cleanup process.
- Molecular Traps: Ferrihydrite uses a diverse toolkit of chemical bonds—including electrostatic adsorption, ligand exchange, and even "lattice doping"—to pin chromium and carbon in place.
- Double Benefit: This process doesn't just immobilize the toxic Cr(VI); it also sequesters carbon. By binding organic carbon to the mineral surface, it prevents that carbon from being released back into the atmosphere as CO2.
- Real-World Success: The team didn't just stay in the lab. Leaching experiments on actual contaminated mine soil confirmed that using organic matter alongside in situ iron minerals effectively "locks down" the chromium, preventing it from washing away into groundwater.
Implications for a Greener Future
The discovery of how these low-crystallinity iron minerals function provides a new blueprint for environmental remediation. Instead of relying on energy-intensive chemical treatments, engineers can now look toward synergetic strategies that use natural organic matter and specific iron minerals to heal damaged landscapes. By improving our understanding of the geochemical cycling of iron, chromium, and carbon, the team at Tongji University is paving the way for technologies that solve two problems at once: cleaning up toxic legacies and fighting climate change through carbon sequestration.
Corresponding Author:
Bin Dong College of Environmental Science and Engineering, Tongji University, Shanghai, China. Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, China.
Journal
Carbon Research
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Decomposition of cyanobacteria and submerged macrophytes: impacts on carbon emissions and nutrient cycling in lake ecosystems
Article Publication Date
26-Mar-2026
Biochar-based nanotechnology cleans toxic herbicide from soil while protecting crops
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Novel multi-interface regulation of acetochlor fate in a soil-plant system using N-doped biochar-modified zero-valent iron nanocomposites for enhanced degradation and protective root iron plaque formation
view moreCredit: Xiangyu Zhang, Peng Zhang, Le Jiao, Yanwei Zhang, Hongwen Sun & Chenglan Liu
A new study has developed an innovative biochar-based nanomaterial that can rapidly remove harmful herbicides from soil while simultaneously protecting crops from contamination. The research offers a promising solution to one of agriculture’s most persistent challenges: balancing soil remediation with food safety.
“Traditional methods often focus only on removing pollutants from soil, but they overlook how these chemicals and their byproducts still enter crops,” said the study’s corresponding author. “Our approach addresses both problems at once, ensuring cleaner soil and safer food.”
Herbicides such as acetochlor are widely used worldwide but pose serious environmental and health risks. Classified as a possible carcinogen, acetochlor can persist in soil and be absorbed by crops, reducing yields and threatening food safety. Even more concerning, its breakdown products can be more mobile and easily taken up by plants.
To tackle this issue, researchers designed a nitrogen-doped biochar-modified zero-valent iron nanocomposite, known as NC-ZVI. This material combines biochar with iron nanoparticles to create a highly reactive system capable of interacting with soil, pollutants, and plant roots simultaneously.
In laboratory and greenhouse experiments, NC-ZVI removed about 90 percent of acetochlor from soil within just seven days, and up to 96.7 percent after three weeks. This performance significantly outpaced conventional materials, which showed much lower degradation efficiency.
But the innovation goes beyond pollutant removal. The material also triggered the formation of a natural protective layer on plant roots known as iron plaque. This layer acts as a barrier that captures contaminants before they can enter the plant.
As a result, the total amount of acetochlor and its byproducts inside maize plants was reduced by more than 80 percent. At the same time, crop health improved dramatically. Maize biomass increased by over 200 percent compared with plants grown in contaminated soil without treatment.
“This dual function is the key breakthrough,” the authors explained. “We are not only cleaning the soil but also actively preventing pollutants from entering the food chain.”
The study further revealed how the material works at a microscopic level. The engineered biochar and nitrogen doping enhance electron transfer and catalytic activity, allowing the material to break down herbicides more efficiently. Meanwhile, its unique surface properties help pull pollutants out of soil particles, making them easier to degrade.
Importantly, the technology also supports soil health. The researchers found that microbial communities disrupted by herbicide contamination were partially restored after treatment. This suggests the material can help rebuild ecological balance rather than harm it.
Cost and scalability are also promising. The production cost of NC-ZVI is estimated to be less than one tenth that of conventional nano iron materials, making it a practical option for large-scale agricultural use.
The researchers emphasize that this approach represents a new direction in environmental remediation. Instead of treating soil and crops as separate systems, it integrates both into a single solution.
“This work provides a new strategy for sustainable agriculture,” the authors noted. “By combining material innovation with plant-soil interactions, we can improve environmental quality and ensure food safety at the same time.”
While further field studies are needed to evaluate long-term impacts, the findings highlight the potential of biochar-based nanotechnology to transform how contaminated soils are managed worldwide.
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Journal Reference: Zhang, X., Zhang, P., Jiao, L. et al. Novel multi-interface regulation of acetochlor fate in a soil-plant system using N-doped biochar-modified zero-valent iron nanocomposites for enhanced degradation and protective root iron plaque formation. Biochar 8, 48 (2026).
https://doi.org/10.1007/s42773-025-00567-8
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About Biochar
Biochar (e-ISSN: 2524-7867) is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
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Journal
Biochar
Method of Research
Experimental study
Article Title
Novel multi-interface regulation of acetochlor fate in a soil-plant system using N-doped biochar-modified zero-valent iron nanocomposites for enhanced degradation and protective root iron plaque formation
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