The Innovation Team of Soil-Plant Interactions at the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has made significant progress in the utilization of agricultural waste resources. 

Their research, titled "Efficient recovery of rare metal lanthanum from water by MOF-modified biochar: DFT calculation and dynamic adsorption", has been published in the leading soil science journal "Biochar" (IF=13.1).

Rare earth elements, regarded as the "industrial vitamins," are non-renewable resources extensively utilized in precision chemical engineering, military, and agricultural fields. The mining process generates a large amount of low-concentration wastewater, resulting in resource lose and environmental pollution. Traditional adsorption materials are deficient in capacity and selectivity, highlighting the urgent need for efficient and environmentally friendly new adsorbents.

Based on chemical simulation, the team used rice husk biochar as a carrier and in situ grew iron-based metal-organic frameworks (MOF), creating a novel MOF modified biochar composite. At pH 6.0, the maximum adsorption capacity for lanthanum ions reached 288.89 mg g-1, doubling that of the original biochar. Even after 4 cycles of elution, it maintained over 93% adsorption efficiency and structural stability. At 0.2 g L-1, it could reduce the lanthanum ions concentration in surface runoff water from Jiangxi rare earth mining area to below the ecological safety threshold (10.1 ng mL-1). Dynamic adsorption tests showed stable operation for 540 minutes in continuous flow, with an adsorption capacity of 121 mg g-1. 

Density functional theory calculations revealed that the adsorption mechanism of lanthanum ions by the composite material involves π-π interactions and ligand exchange, mainly through Fe-O-La coordination bond formation and surface hydroxyl ligand exchange. This achievement not only elucidates the atomic-level adsorption mechanism of MOF@biochar composite but also demonstrates its efficiency and stability in rare earth wastewater treatment, providing a new strategy for the green recovery of rare earth resources. This method combines theoretical innovation with engineering application, promoting the integration of functional material design and environmental remediation technology, and creating a new field for the utilization of agricultural waste resources.

Dr. Huang Qilan, a doctor candidate at the IARRP is the first author, and Professor Zhang Qianru is the corresponding author. The research was jointly funded by the State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, the International Science & Technology Innovation Program of the Chinese Academy of Agriculture Science, and Young Scientist Exchange Program between the People’s Republic of China and the Republic of Korea.

Citation:

Huang Q.L., Zhang Q.R., Zhao S.W., Zhang C.C., Guan H.X., Liu J.Q. 2025. Efficient recovery of rare metal lanthanum from water by MOF-modified biochar: DFT calculation and dynamic adsorption. Biochar. 7:29.

Original article link: https://doi.org/10.1007/s42773-024-00419-x