Engineered hydrochar removes and breaks down antibiotic pollution in water

Antibiotic pollution in water is an escalating global concern, driven largely by agricultural use. Now, researchers have developed a new type of engineered hydrochar that not only captures antibiotics from water but also breaks them down into less harmful substances.

“We wanted to design a material that does more than just trap pollutants,” said one of the study’s lead researchers. “Our goal was to create a system that can both remove and degrade antibiotics efficiently, without requiring additional chemicals.”

The study focuses on tetracycline, a widely used antibiotic in livestock production. More than 70 percent of tetracycline administered to animals is excreted and can enter soil and water systems, where it contributes to antibiotic resistance and ecological risks. Traditional treatment methods often rely on adsorption, which captures contaminants but does not destroy them.

To address this limitation, the research team developed a novel hydrochar derived from seed meal biomass and enhanced it through a combination of nitrogen doping, iron and manganese incorporation, and mechanochemical ball milling. The resulting material, referred to as Fe/Mn-BNHT, demonstrated a removal efficiency of up to 95 percent for tetracycline in water.

Unlike conventional adsorbents, the new material goes a step further by degrading the antibiotic after adsorption. Experiments showed that approximately 87 percent of the captured tetracycline was broken down, significantly reducing the risk of secondary pollution.

The material works through a combination of mechanisms. Tetracycline molecules are first attracted to the hydrochar surface via electrostatic interactions, hydrogen bonding, and surface complexation. Once bound, the pollutant undergoes degradation driven by reactive oxygen species and electron transfer processes. The study identified hydroxyl radicals as key reactive species, while the presence of iron, manganese, and nitrogen sites facilitates electron exchange that accelerates chemical breakdown.

Importantly, the hydrochar performed well under a wide range of environmental conditions. It maintained high removal efficiency across pH levels from 3 to 9 and showed resilience in the presence of common ions and organic matter. Even after five reuse cycles, the material retained over 70 percent of its removal capacity.

“This stability and reusability are critical for real-world applications,” the researcher noted. “We need materials that can perform reliably in complex water systems.”

The study also assessed the environmental safety of the degradation process. Using computational and experimental analyses, the team identified ten intermediate compounds formed during tetracycline breakdown. Most of these intermediates showed lower toxicity than the original antibiotic, suggesting that the process reduces ecological risk rather than transferring it elsewhere.

Another advantage of the system is its simplicity. Unlike advanced oxidation processes that require added oxidants or energy inputs, this hydrochar operates without external chemical agents. This makes it a potentially low-cost and scalable solution for water treatment, particularly in agricultural and rural settings.

The researchers emphasize that their findings highlight the importance of designing multifunctional carbon materials with active sites that enable both adsorption and degradation. Such materials could play a key role in addressing emerging contaminants, including antibiotics and other organic pollutants.

Future work will focus on optimizing the material for complex environmental systems where multiple pollutants coexist and improving its resistance to interference from bicarbonate ions, which were found to reduce performance under certain conditions.

Overall, the study provides a promising pathway toward safer and more effective strategies for mitigating antibiotic pollution in water systems.

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Journal Reference: Li, X., Li, L., Zhang, Z. et al. Insights into the mechanism of mechanically treated Fe/Mn-N doped seed meal hydrochar for efficient adsorption and degradation of tetracycline. Biochar 7, 48 (2025).   

https://doi.org/10.1007/s42773-025-00435-5   

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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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