Two-step pyrolysis biochar derived from agro-waste for antibiotics removal: Mechanisms and stability

This study used acetone washing biochar (BCA) and nitric-acid washing biochar (BCN) derived from bagasse to remove sulfamethoxazole (SMX) and tetracycline (TC) in water. Higher specific surface area (1119.53 m² g^-1) and graphitization degree can significantly improve decontamination efficacy, of which BCN has the highest SMX and TC sorption capacities (274.63 mg g^-1 and 353.85 mg g^-1). The kinetics, isotherms and characterization analysis indicated O-containing functional group complexation and π-π interaction were dominant mechanisms in the adsorption process. Adsorption stability experiment showed that BCA has better stability with the coexistence of anions and cations. Besides, the enhancement and competitive adsorption from the interaction between soluble organic matter and TC could facilitate TC decontamination. Therefore, bagasse biochar derived from agro-waste has a promising potential for antibiotic contaminants removal from multi-interference conditions and promotes the recycling of waste, thereby achieving harmony between materials and the ecological environment.