Effective adsorption of norfloxacin from water on magnetic biochar composite derived from cellulase hydrolysis apple branch: Synthesis optimization, performance assessment and mechanism insight

Based on the optimization of feedstock and temperature condition, we synthesized a novel biochar composite (CHMAB) by pyrolyzing apple branch after cellulase hydrolysis and magnetization as well as coating them with humic acid (HA). Compared with the simultaneously prepared magnetic biochar (MAB) and HA-coated magnetic biochar (HMAB), batch adsorption test results showed that CHMAB had the best norfloxacin (NOR) removal performance in a wide pH range (2−12). The endothermic and spontaneous adsorption behavior of NOR on CHMAB could be better suited to the pseudo-second-order model and Langmuir model with maximum absorption capacity (81.08 mg g−1) at 35℃. Pore filling, π-π EDA interactions, hydrogen bonding, surface complexation, electrostatic interactions and hydrophobic interactions might all be implicated in the NOR removal process. Additionally, the regenerated CHMAB still maintained 99.23% removal efficiency for 0.1 mol L−1 NOR and performed well after seven cycles. These findings highlighted the possibility of enhancing the adsorption capacity of biochar for antibiotics by modification through cellulase hydrolysis of precursor and HA coating procedure. It is noteworthy that the use of low-cost agricultural and forestry wastes to produce adsorbents for emerging contaminants such as antibiotics could have greater potential for future practical applications under the ongoing dual carbon policy.