Chitosan-modified Biochar unveils new mechanism for efficient removal of nitrogen-containing pollutants from water

Neonicotinoid pesticides, once considered efficient and low-toxicity solutions, have caused global water contamination due to their extensive use. Growing evidence reveals their far-reaching harms, ranging from triggering colony collapse disorder in honeybees and population declines in insectivorous birds, to posing potential threats to human health—including reproductive risks and impaired neurodevelopment. Compounding the problem, conventional water treatment technologies are ineffective at removing these pesticides.

In a study published in the KeAi journal Environmental Chemistry and Ecotoxicology, a research team from China has developed a solution using an engineered “nitrogen-doped” biochar. By subjecting common biomass—white melon seed shells—and chitosan to high-temperature pyrolysis, they produced a highly efficient adsorbent named NBC900.

“This material demonstrated a capacity for capturing imidacloprid (IMI) from water, achieving a removal rate of 97.2% and an adsorption capacity of 140.1 mg/g—performance that surpasses most existing adsorbents,” shares senior and co-corresponding author Guorui Liu, a professor at the Zhejiang Key Laboratory of Digital Intelligence Monitoring and Restoration of Watershed Environment, Zhejiang Normal University.

Characterization studies revealed that nitrogen groups (specifically pyridinic-N) incorporated into the biochar act as electron donors, engaging in strong "Lewis acid-base" interactions with electron-accepting groups on the IMI molecule. This, combined with other mechanisms like pore-filling and π-π interactions, drives the effective adsorption.

“NBC900 acts as a versatile and powerful magnet for the pesticide; the nitrogen modification we introduced is crucial, as it creates more active sites and facilitates stronger chemical bonding with the nitrogen-containing pollutant,” explains Liu. “It performed consistently across a wide range of water conditions (pH 2-11), showed strong resistance to interference from common ions, and maintained its effectiveness even after multiple regeneration cycles.”

According to co-corresponding author Song Cui, a professor at the International Joint Research Center for Persistent Toxic Substances of Northeast Agricultural University, while the study demonstrates immediate application in IMI removal, its deeper value lies in significantly advancing the mechanistic understanding of biochar's interaction with NNIs and similar N-containing pollutants.

“We hope these findings encourage the broader development of N-modified graphitic biochar as efficient, targeted, and sustainable tools for environmental remediation, ultimately advancing both resource utilization and ecological protection in a meaningful and impactful way,” says Cui.

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Contact the author:

Song Cui, International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, China, cuisong-bq@neau.edu.cn

Guorui Liu, Zhejiang Key Laboratory of Digital Intelligence Monitoring and Restoration of Watershed Environment, College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, China, liiugr@zjnu.edu.cn

The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).