Excess fluoride in water is a persistent environmental and public health concern in many parts of the world. Now, researchers have developed a new plant-derived material that can capture fluoride efficiently while also creating value from invasive plant biomass.
A research team led by Jiunian Guan at Northeast Normal University has developed a nano-magnesium oxide modified pyro-hydrochar, or nMgO/Py-HyC, made from residues of the invasive plant Rhus typhina. The material achieved a maximum fluoride adsorption capacity of 469.64 milligrams per gram, outperforming the MgO-based adsorbents compared in the study.
"Our goal was to address two environmental challenges at the same time: fluoride contamination in water and the growing accumulation of invasive plant biomass," said Jiunian Guan, corresponding author of the study. "By converting this biomass into a functional carbon material and combining it with nano-magnesium oxide, we created an adsorbent with strong fluoride-removal performance and promising environmental adaptability."
Fluoride occurs naturally in groundwater, but industrial activities such as semiconductor manufacturing, glass production, electroplating, lithium refining, pesticide production and pharmaceutical manufacturing can also generate fluoride-containing wastewater. Excessive fluoride exposure can cause serious health problems, making effective treatment technologies important for both drinking water protection and industrial wastewater management.
The researchers first converted Rhus typhina biomass into hydrochar and then produced the magnesium-containing composite through a relatively simple pyrolysis process. The resulting porous carbon structure helped disperse nano-MgO particles and provided numerous sites where fluoride could be captured.
A major advantage was the material's ability to perform under different water conditions. Fluoride adsorption remained stable across a broad pH range from 5.0 to 11.0. Common coexisting ions such as nitrate and sulfate caused little interference, although high concentrations of bicarbonate reduced fluoride uptake.
Detailed material analyses revealed that fluoride was not captured through a single process. Instead, several mechanisms worked together, including electrostatic attraction, surface complexation, anion and ligand exchange, precipitation, and hydrogen bonding. Fluoride could interact directly with magnesium and form stable compounds such as MgF₂ and fluorine-containing magnesium hydroxide phases.
The researchers also observed a clear synergistic effect between the carbon support and nano-MgO. Under the same experimental conditions, the adsorption capacity of the combined material was substantially greater than the capacities of the two components considered separately. Its porous framework helped expose active magnesium sites and improved contact between fluoride ions and the adsorbent.
The study therefore points to a potential circular strategy: invasive plant residues can be transformed from an ecological management burden into a useful material for water remediation.
The authors note that further work is needed to evaluate the material under different real-world wastewater conditions and at engineering scale. Still, the findings provide a promising foundation for developing high-efficiency, low-carbon fluoride treatment technologies based on renewable biomass resources.
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Journal reference: Tong Y, Wang D, Gu L, Tai Y, Tang X, et al. 2026. Nano-MgO/pyro-hydrochar for enhancing adsorption of fluoride ion from aqueous solution: performance, influencing factors, and mechanisms. Biochar X 2: e023 doi: 10.48130/bchax-0026-0021
https://www.maxapress.com/article/doi/10.48130/bchax-0026-0021
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About the Journal:
Biochar X (e-ISSN: 3070-1686) is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
