Chitosan-modified Biochar Unveils New Mechanism for Efficient Removal of Nitrogen-containing Pollutants from Water

ADSORPTION MECHANISM OF IMIDACLOPRID ON N-MODIFIED BIOCHAR IN AQUEOUS SYSTEMS.

GA, UNITED STATES, November 4, 2025 /EINPresswire.com/ -- Researchers have developed a nitrogen-doped graphitic biochar using chitosan for efficient removal of nitrogen-containing contaminants, such as imidacloprid, from water. The material demonstrated notable adsorption performance, achieving a capacity of 140.1 mg/g and a removal efficiency of 97.2% for imidacloprid. The study reveals the key role of nitrogen-functional groups, particularly pyridinic-N and graphitic-N, in driving the adsorption process through π–π interactions and Lewis acid-base reactions. These findings provide valuable insights for designing advanced adsorbents for environmental remediation.

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.

DOI
10.1016/j.enceco.2025.07.023

Original Source URL
https://doi.org/10.1016/j.enceco.2025.07.023

Funding information
This work was supported by the National Natural Science Foundation of China (No. 52479037), the Distinguished Youth Science Foundation of Heilongjiang Province, China (JQ2023E001), and Young Leading Talents of Northeast Agricultural University, China (NEAU2023QNLJ-013 and NEAU2024QNLJ-01).

Lucy Wang
BioDesign Research
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