New biochar composite offers efficient route to recover valuable rare earth elements from water
image: Efficient recovery of rare metal lanthanum from water by MOF-modified biochar: DFT calculation and dynamic adsorption
Credit: Qilan Huang, Qianru Zhang, Shuwen Zhao, Chuchen Zhang, Huixin Guan & Jianqiao Liu
A new study reports a highly effective and sustainable material for capturing rare earth elements from water, offering a promising solution to both resource scarcity and environmental pollution.
Rare earth elements are essential for modern technologies, from electronics and renewable energy systems to advanced manufacturing. However, their extraction generates large volumes of wastewater containing low concentrations of these valuable metals. Recovering them efficiently has remained a major scientific and engineering challenge.
In research published in Biochar, scientists developed a novel composite material by combining biochar derived from rice husks with a metal-organic framework known as MIL-88b. The resulting material, called MIL-88b@BC, significantly improves the ability to capture lanthanum ions from water.
“Rare earth elements are critical for many industries, yet they are difficult to recover once dispersed in wastewater,” said one of the study’s authors. “Our work demonstrates a practical and efficient strategy to both remove and recycle these valuable metals using a low-cost and environmentally friendly material.”
The composite takes advantage of the strengths of both components. Biochar is inexpensive, sustainable, and rich in carbon, while metal-organic frameworks offer high surface area and tunable chemistry. By integrating the two, the researchers created a material with enhanced adsorption capacity and improved structural stability in water.
Laboratory tests showed that the new composite achieved a maximum lanthanum adsorption capacity of nearly 289 milligrams per gram, far exceeding many previously reported materials. The adsorption process followed well-established kinetic and isotherm models, indicating a strong and predictable interaction between the material and the target metal ions.
To better understand how the material works, the team combined experiments with density functional theory simulations. These calculations revealed that lanthanum ions are captured through a combination of ligand exchange and interactions with oxygen-containing functional groups on the material surface. The formation of stable chemical bonds between lanthanum and iron-oxygen sites played a key role in the high performance.
Importantly, the material also demonstrated strong recyclability. After multiple cycles of use and regeneration, it retained over 90 percent of its adsorption efficiency. This durability is critical for real-world applications, where cost and long-term performance are key considerations.
The researchers further tested the material in realistic conditions using water samples collected near a rare earth mining area. Even in the presence of competing ions, the composite maintained high selectivity for lanthanum, highlighting its robustness in complex environmental systems.
Beyond batch experiments, column tests simulating continuous treatment processes showed that the material performs well under dynamic conditions. These results suggest that the technology could be scaled up for industrial wastewater treatment and resource recovery.
The study highlights the broader potential of combining biochar with advanced materials to address environmental challenges. By transforming agricultural waste into high-performance adsorbents, this approach aligns with circular economy principles while contributing to cleaner water systems.
As global demand for rare earth elements continues to grow, innovative recovery technologies will become increasingly important. This research provides a pathway toward more sustainable management of these critical resources, reducing environmental impacts while unlocking economic value from waste streams.
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Journal Reference: Huang, Q., Zhang, Q., Zhao, S. et al. Efficient recovery of rare metal lanthanum from water by MOF-modified biochar: DFT calculation and dynamic adsorption. Biochar 7, 29 (2025).
https://doi.org/10.1007/s42773-024-00419-x
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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.