Removal of emerging contaminants (ECs) from aqueous solutions by modified biochar: A review

The increasing concern over emerging contaminants (ECs) in aqueous solutions is driven by their potential risks to public health. Handling ECs becomes an urgent mission in the world. Biochar has been applied for ECs removal in wastewater for its low cost and satisfactory efficiency, while its practical applications are hindered by the limited adsorption capacity. To improve the removal efficiency of biochar on ECs, diverse techniques (acid-base modification, metal compound modification, steam activation, magnetization, heteroatom doping, and ball milling) have been applied to modify biochar and imbue it with a range of physicochemical attributes. This leads to unique adsorption outcomes, behaviors, and mechanisms. Herein, effective modification methods, effects and mechanisms of modified biochar on the removal of typical ECs including per- and polyfluoroalkyl substances (PFASs), antibiotics and antibiotic resistance genes (ARGs), micro(nano)plastics, and endocrine disrupting compounds (EDCs) in aqueous solution have been systematically discussed. Modified biochar has upgraded removal performance towards ECs, and the removal mechanisms generally follow two pathways: adsorption and catalytic degradation. Future efforts should focus on establishing standardized evaluation criteria for cost, effectiveness, and environmental risk, and leverage artificial intelligence to broaden the applications of modified biochar in ECs removal.