Enhancing norfloxacin adsorption via NF dual-site non-metal functionalized biochar: Performance and mechanism

Given the limited performance of traditional biochar adsorbents, this study proposes an innovative two-step pyrolysis strategy for the precise synthesis of N F double-site co-doped biochars (NFBCs). This strategy effectively regulates the pore structure and surface chemistry of the material. The optimized material (NFBCs-1:3) exhibited an ultra-high specific surface area (2187 m 2 /g) and abundant active sites. Its maximum adsorption capacity for norfloxacin (NOR) reached 552.65 mg/g, significantly exceeding that of traditional biochar and most reported materials. The adsorption process followed pseudo-second-order kinetics and the Sips model. Mechanistic studies showed that its excellent performance stems from the synergistic effects of pore filling, π-π interactions, hydrogen bonding, and electrostatic interactions, with the unique N F double-site regulation of the electronic structure as the key. In addition, NFBCs-1:3 maintained excellent adsorption performance across a wide pH range, under coexisting ion interference, and in a variety of real-world water matrices, confirming its great application potential in the treatment of complex real-world wastewater. This study provides a new idea for the design of efficient and stable non-metal-doped carbon-based adsorbents.