Turning waste into a solution: Biochar shows promise for cleaning uranium-contaminated water and soil

Uranium contamination is an urgent environmental challenge with serious implications for ecosystems and human health. A new review highlights how biochar, a carbon-rich material made from waste biomass, could offer a sustainable and cost-effective solution for removing uranium from polluted water and soil.

In a comprehensive analysis of more than 110 studies, researchers demonstrate that biochar-based materials can effectively capture and immobilize uranium, particularly its most mobile and hazardous form, U(VI). The study shows that with appropriate modification, biochar can achieve high adsorption capacities while maintaining environmental compatibility.

“Biochar provides a unique opportunity to turn waste into a valuable material for environmental cleanup,” the authors explain. “By tailoring its surface properties, we can significantly enhance its ability to remove uranium from complex environments.”

Uranium is widely used in nuclear energy, medicine, and industry, but its release into the environment through mining, waste disposal, and industrial activities has raised growing concern. In water systems, uranium exists mainly as soluble uranyl ions, which are highly mobile and can spread quickly through groundwater. In soils, uranium can disrupt microbial activity, damage plant growth, and enter the food chain, posing long-term risks to human health.

Traditional remediation methods such as chemical precipitation and membrane filtration are often expensive, energy-intensive, and may generate secondary pollution. In contrast, biochar offers a greener alternative. Produced by heating organic waste such as agricultural residues, manure, or sludge under limited oxygen conditions, biochar has a porous structure, large surface area, and abundant functional groups that make it highly effective for contaminant removal.

The review identifies several key mechanisms behind uranium removal by biochar. These include physical adsorption, surface complexation with oxygen-containing functional groups, and chemical reduction that transforms soluble uranium into less mobile forms. Modified biochar materials, especially those enriched with oxygen, phosphorus, or metal oxides, show significantly improved performance compared to unmodified biochar.

For example, chemical treatments can introduce functional groups such as carboxyl and phosphate, which strongly bind uranium ions. Metal-doped biochar, including iron- or bismuth-based materials, can further enhance removal by promoting redox reactions that convert uranium into more stable forms. Biological modifications using microorganisms also show promise by increasing surface activity and selectivity.

Importantly, the study emphasizes that biochar is not only effective but also sustainable. It can be produced from low-cost waste materials, contributes to carbon sequestration, and supports circular economy principles. In addition, many biochar-based materials can be regenerated and reused multiple times with only minor loss of performance, further improving their economic viability.

Environmental conditions such as pH play a critical role in uranium removal. The review finds that slightly acidic conditions, typically between pH 4 and 6, are optimal for adsorption, as they favor the interaction between positively charged uranium species and negatively charged biochar surfaces.

Despite these promising results, the authors note that most studies remain at the laboratory scale. Future research should focus on scaling up production, improving long-term stability, and evaluating performance in real-world contaminated sites.

“Our findings highlight the strong potential of engineered biochar as a green material for uranium remediation,” the researchers conclude. “With continued innovation, biochar-based technologies could become a key tool for addressing radioactive contamination while advancing sustainable development.”

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Journal Reference: Xiong, X., Liu, J., Xiao, T. et al. Remediation of uranium-contaminated water and soil by biochar-based materials: a review. Biochar 7, 41 (2025).   

https://doi.org/10.1007/s42773-025-00438-2  

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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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