Micro- and nanoplastics (MNPs) have emerged as persistent and ubiquitous contaminants in aquatic environments due to their small size, chemical stability, and strong affinity for toxic pollutants, posing significant risks to ecosystems and human health. Conventional water treatment technologies are largely ineffective for their removal, necessitating the development of innovative and sustainable remediation strategies. Among emerging solutions, biochar has gained considerable attention as a low-cost, eco-friendly, and efficient adsorbent. This review critically evaluates recent advances in biochar-based adsorbents for the removal of MNPs from water systems. Particular emphasis is placed on the role of physicochemical properties, including surface area, porosity, surface functional groups, and pyrolysis conditions, as well as the impact of modification techniques on adsorption performance. Key removal mechanisms, such as pore filling, electrostatic attraction, hydrophobic interactions, surface complexation, and π–π electron donor–acceptor interactions, are systematically analyzed. Comparative assessment of different biochar types indicates that iron-modified and corncob-derived biochars exhibit superior adsorption efficiencies. However, despite promising laboratory-scale performance, several challenges remain, including limited regeneration capacity, potential secondary pollution, and reduced efficiency under complex environmental conditions. Future research should focus on optimizing biochar modification, integrating adsorption with complementary treatment technologies, and conducting life cycle and techno-economic assessments. Overall, biochar represents a promising and sustainable approach for mitigating micro- and nanoplastic pollution in aquatic systems, although further research is required to enable large-scale application. However, the lack of standardized evaluation frameworks and limited validation under realistic environmental conditions restrict the comparability and scalability of current findings.

Keywords: Nanoplastics, Microplastics, Removal, Biochar, Plastic Pollution, Water Pollution, Electrostatic Attraction, Hydrophobic Interaction.

Alomar, C., Estarellas, F., & Deudero, S. (2016). Microplastics in the Mediterranean Sea: deposition in coastal shallow sediments, spatial variation, and preferential grain size. Marine Environmental Research, 115: 1–10. https://doi.org/10.1016/j.marenvres.2016.01.005.

Dube, E., & Okuthe, G.E. (2023). Plastics and micro/nano-plastics (MNPs) in the environment: occurrence, impact, and toxicity. International Journal of Environmental Research and Public Health, 20(17): 6667. https://doi.org/10. 3390/ijerph20176667.

Thushari, G.G.N., & Senevirathna, J.D.M. (2020). Plastic pollution in the marine environment. Heliyon, 6(8): e04709. https://doi.org/10.1016/j.heliyon.2020.e04709.

Kiran, B.R., Kopperi, H., & Venkata Mohan, S. (2022). Micro/nano-plastics occurrence, identification, risk analysis and mitigation: challenges and perspectives. Reviews in Environmental Science and Bio/Technology, 21(1): 169–203. https://doi.org/10.1007/s11157-021-09609-6.

Ahmed, R., Hamid, A.K., Krebsbach, S.A., et al. (2022). Critical review of microplastics removal from the environment. Chemosphere, 293: 133557. https://doi.org/10.1016/j.chemosphere.2022.133557.

Prata, J.C., da Costa, J.P., Lopes, I., et al. (2020). Environmental exposure to microplastics: an overview on possible human health effects. Science of the Total Environment, 702: 134455. 

Jayavel, S., Govindaraju, B., Michael, J.R., & Viswanathan, B. (2024). Impacts of micro and nanoplastics on human health. Bulletin of the National Research Centre, 48(1): 110. https://doi.org/10.1186/s42269-024-01268-1.

Min, K., Cuiffi, J.D., & Mathers, R.T. (2020). Ranking environmental degradation trends of plastic marine debris based on physical properties and molecular structure. Nature Communications, 11(1): 727. 

Wei, W., Chen, X., & Ni, B.J. (2021). Different pathways of microplastics entering the sludge treatment system distinctively affect anaerobic sludge fermentation processes. Environmental Science & Technology, 55(16): 11274–11283. https://doi.org/10.1021/acs.est.1c02300.

Zhang, Y., Zhu, C., Liu, F., et al. (2019). Effects of ionic strength on removal of toxic pollutants from aqueous media with multifarious adsorbents: a review. Science of the Total Environment, 646: 265–279. https://doi.org/10. 1016/j.scitotenv.2018.07.279.

Chen, Z., Fang, J., Wei, W., et al. (2022). Emerging adsorbents for micro/nanoplastics removal from contaminated water: advances and perspectives. Journal of Cleaner Production, 371: 133676. 

Dong, M., He, L., Jiang, M., et al. (2023). Biochar for the removal of emerging pollutants from aquatic systems: a review. International Journal of Environmental Research and Public Health, 20(3): 1679. 

Wang, J., Sun, C., Huang, Q.X., et al. (2021). Adsorption and thermal degradation of microplastics from aqueous solutions by Mg/Zn modified magnetic biochars. Journal of Hazardous Materials, 419: 126486. 

Tang, S., Gao, L., Zhao, T., & Tian, A. (2024). Enhancing the removal efficiency of microplastics in drinking water treatment. Journal of Water Process Engineering, 57: 104630. 

Xiang, W., Zhang, X., Chen, J., et al. (2020). Biochar technology in wastewater treatment: a critical review. Chemosphere, 252: 126539. https://doi.org/10.1016/j.chemosphere.2020.126539.

Du, C., Zhang, Z., Yu, G., et al. (2021). A review of metal organic framework (MOFs)-based materials for antibiotics removal via adsorption and photocatalysis. Chemosphere, 272: 129501. 

Panahi, H.K.S., Dehhaghi, M., Ok, Y.S., et al. (2020). A comprehensive review of engineered biochar: production, characteristics, and environmental applications. Journal of Cleaner Production, 270: 122462. 

Varkolu, M., Gundekari, S., et al. (2025). Recent advances in biochar production, characterization, and environmental applications. Catalysts, 15(3): 243. https://doi.org/10.3390/catal15030243.

Lan, W., Zhao, X., Wang, Y., et al. (2024). Research progress of biochar modification technology and its application in environmental remediation. Biomass and Bioenergy, 184: 107178. 

Tan, X.F., Zhu, S.S., Wang, R.P., et al. (2021). Role of biochar surface characteristics in the adsorption of aromatic compounds: pore structure and functional groups. Chinese Chemical Letters, 32(10): 2939–2946. 

Source of Funding:

Not applicable.

Competing Interests Statement:

Authors have declared no competing interests.

Consent for publication:

The authors declare that they consented to the publication of this study.

Authors' contributions:

Peter Mafimisebi: Writing – review, editing, original draft, Akinbobola Ogundiran Writing – review & editing, Saeed Muhammad: Writing – review & editing, Niniola Olateju: Writing – review & editing.

Informed Consent:

Not applicable for this study.

Availability of Data and Material:

This review article synthesizes data from previously published studies, and no new primary data were generated. All data supporting the findings are derived from the literature cited in the references. Figures are used with permission from their respective sources. For access to the original data, please refer to the cited publications.

Institutional Review Board Statement:

Not applicable for this study.