Meso/microporous biochar derived from coactivation with calcium and potassium salts for efficient removal of emerging contaminants

The coactivation of biomass using different metal salts remains underexplored despite its potential to engineer hierarchical porosity in biochar. Herein, we report a sustainable and innovative strategy for converting bamboo waste into meso/microporous biochar (MMB) through simultaneous activation with K 2 CO 3 and CaCO 3 . The resulting MMB features a high specific surface area of 1811.31 m 2 /g and a total pore volume of 1.01 cm 3 /g. When evaluated for diethyl phthalate removal, MMB achieves a maximum sorption capacity of 930.56 mg/g according to the Sips model, considerably exceeding those of conventional biochars and commercial activated carbons. More importantly, MMB also demonstrates high performance toward sulfamethoxazole, a representative antibiotic, with a maximum sorption of 676.27 mg/g according to the Sips model. Mechanistic analyses reveal that pore filling, hydrophobic partitioning, hydrogen bonding, and π–π stacking collectively govern the sorption of organic pollutants. Furthermore, MMB exhibits excellent reusability over five cycles, growth-stimulating properties, and robust performance in real water matrices (tap water, lake water, and domestic sewage). The preliminary material-and-energy cost of MMB is estimated to be 9.52 $/kg, which is lower than that of activated carbon prepared via KOH activation. This coactivation paradigm offers a facile, cost-effective, and scalable route for upgrading biowaste into high-performance sorbents, addressing the simultaneous challenges of emerging pollutant remediation and waste valorization. Download: Download high-res image (175KB) Download: Download full-size image