Smart biochar that remembers pollutants offers a new way to clean water and recycle biomass

(Press-News.org) Scientists have combined molecular imprinting technology with biochar to create materials that can recognize and capture specific molecules with remarkable precision. Biochar is a porous carbon material made by heating biomass such as crop residues in low-oxygen conditions, and is already valued for its low cost, large surface area, and environmental friendliness.​

Molecular imprinting works by “teaching” a polymer to remember the shape and chemical features of a target molecule, then locking that memory into tiny recognition cavities.​

When these molecularly imprinted polymers are built on biochar, the result is a composite that unites broad adsorption capacity with highly selective binding for chosen pollutants.​

“Our goal is to turn low-value biomass into high-value smart sorbents that can precisely target contaminants rather than treating all pollutants as the same,” says lead author Jiaheng Li of Capital Normal University.​

From agricultural waste to precision pollutant traps The review, published in Biochar X, systematically summarizes how researchers prepare, modify, and apply molecularly imprinted biochar materials and what makes them different from conventional adsorbents. The authors describe three key design choices: the imprinting mechanism, the polymerization method, and the selection of building blocks such as functional monomers, crosslinkers, and initiators.​

Noncovalent imprinting, which relies on hydrogen bonding and other weak interactions, has become the most widely used route because it is simple, fast, and compatible with water treatment conditions.​

Common polymerization strategies on biochar supports include precipitation polymerization, emulsion polymerization, electropolymerization on electrodes, and sol–gel processes, each offering different control over particle size, film thickness, and pore structure.​

“By tuning the chemistry on the biochar surface, we can design materials that not only capture a pollutant quickly but also recognize it among dozens of similar chemicals,” notes corresponding author Yuhu Zhang.​

Tackling antibiotics, pesticides, and industrial chemicals Many of the most urgent targets for these materials are trace organic pollutants that are highly toxic at low concentrations, such as antibiotics, pesticides, plasticizers, and disinfection by-products. Standard treatment plants struggle with these compounds because they often occur in complex mixtures and at levels that are difficult to remove efficiently.​

Molecularly imprinted magnetic biochar has been used to selectively remove antibiotics such as oxytetracycline and sulfamethoxazole from water, combining fast adsorption with easy magnetic recovery and reuse.​

Other systems imprint biochar composites to recognize herbicides, pharmaceutical residues, or polycyclic aromatic hydrocarbons, then pair adsorption with advanced oxidation or photocatalysis to degrade the captured pollutants rather than simply transferring them to another waste stream.​

In one example highlighted in the review, an imprinted biochar achieved more than 80 percent equilibrium adsorption of the carcinogenic compound naphthalene within minutes, while a coupled oxidation process degraded the molecule and reopened the imprinted cavities for repeated use.​

Beyond cleanup: sensing and sample preparation The same recognition principle that supports environmental cleanup can also be used to build highly selective sensors and analytical tools. By growing imprinted films directly on conductive biochar-based electrodes, researchers have created electrochemical sensors for antibiotics, heavy metal ions, and plasticizers that respond quickly and selectively in complex samples.​

Molecularly imprinted biochar can serve as a solid-phase extraction material to preconcentrate trace contaminants from biological, food, or environmental samples before chromatographic analysis, improving detection limits and reducing matrix interference.​

Electropolymerized imprinted layers on biochar substrates allow precise control over film thickness and are compatible with in situ monitoring in real time.​

According to the review, this combination of low-cost biomass-derived carbon and tailor-made recognition sites is especially promising for portable sensors and on-site monitoring of water quality.​

Environmental risks and the road to scale-up The authors emphasize that environmental safety and scalability must be addressed before molecularly imprinted biochar can be widely deployed. Potential risks include the release of residual monomers, crosslinkers, or metal oxide nanoparticles from the composite, as well as toxicity associated with the biochar itself if production conditions are not well controlled.​

The review calls for greener synthesis routes, including water-based polymerization, less toxic functional monomers, and careful control of pyrolysis conditions to limit hazardous by-products.​

It also highlights the need for long-term aging studies and full life cycle assessment to quantify impacts such as carbon footprint, leaching behavior, and ecotoxicity compared with existing technologies.​

“From the lab perspective, these materials already show clear advantages in selectivity, capacity, and reusability,” says Zhang. “The next step is to prove that they are safe, economical, and robust enough for continuous operation in real treatment systems.”​

By integrating molecular recognition with biomass recycling, molecularly imprinted biochar materials offer a path toward smarter, more selective pollution control in a warming and increasingly resource-constrained world.​

 

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Journal reference: Li J, Yang B, Yin Z, Sun F, Wang X, et al. 2025. Advances in the preparation, application, and synergistic studies of biochar materials by molecular imprinting techniques: a review. Biochar X 1: e013  

https://www.maxapress.com/article/doi/10.48130/bchax-0025-0013  

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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. 

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