Biochar-Based Sorbents for the Extraction of Emerging Organic Contaminants from Environmental Matrices: A Review

The increasing occurrence of emerging organic contaminants (EOCs) in environmental matrices has intensified the demand for sensitive, selective, and sustainable analytical methods. Sample preparation plays a pivotal role, particularly for trace-level determination in complex matrices. Biochar is a promising sorbent for sample preparation because of its porous structure, tunable surface chemistry, low cost, and potential to be produced from renewable biomass waste. This review examines the use of biochar-based sorbents to extract EOCs from environmental matrices since 2020, with special emphasis on the relationships among precursor biomass, production conditions, surface chemistry, sorption mechanisms, and extraction performance. Agricultural waste was the predominant biomass class, while solid-phase extraction (SPE), magnetic solid-phase extraction (MSPE), and solid-phase microextraction (SPME) were the most frequently reported approaches. Biochar-based extraction has been applied to a wide range of EOCs, with pesticides being the most investigated analyte class. The authors discuss how pyrolysis conditions, activation, surface chemistry, and other parameters affect analyte retention and desorption. The authors compare different extraction approaches in terms of extraction efficiency, precision, and other analytical parameters. Finally, the authors discuss current limitations and research opportunities to guide the development of biochar-based sorbents as sustainable materials for sample preparation and environmental monitoring.