| Abstrakt: |
Low-cost biochar adsorbents show great potential in the treatment of antibiotic wastewater. However, compared with the general emphasis on the excellent adsorption properties of the specific surface area of biochar, the promoting effect of the graphitization structure has been neglected. So this study uses bagasse as a carbon source to prepare magnetic porous graphite biochar (MBC) and tries to explore its adsorption ability. The characterizations show that MBC with a high degree of graphitization exhibits a large specific surface area of 654.30 m2/g and a large mesoporous pore volume of 0.916 cm3/g. MBC shows super-magnetic with the saturation magnetization (MS) of 25 emu/g and can be magnetically separated and recycled in an effective way. It shows good adsorption properties for two typical kinds of antibiotics, tetracycline (TC) and ciprofloxacin (CIP), with the maximum adsorption capacity calculated by the Langmuir model as 691.32 and 609.05 mg/g, respectively. Besides, the adsorption capacity of MBC is excellent in a wide pH range. The adsorption capacity of the regenerated MBC for TC and CIP can remain at 82.15 and 82.99% of the first adsorption capacity after 5 cycles. A more dominative chemisorption mechanism is found to occur in the adsorption of TC and CIP by MBC, indicated by fitting via the aspects of kinetics, isotherm, and thermodynamics. The adsorption mechanism may be mainly based on π–π conjugation, hydrogen bonding, pore filling, and electrostatic attraction. The adsorption process of TC (or CIP) on MBC is not only rate-limited by intraparticle diffusion but also controlled by external diffusion. The adsorption process is endothermic, which can be promoted by increasing temperature. Magnetic porous biochar is prepared via one-step pyrolysis with metal compounds oxidation promoters, showing high adsorption capacity on TC and CIP, the highly graphitized structure plays a vital role. [ABSTRACT FROM AUTHOR] |
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