Preparation of lignin-based biochar with adjustable pore structure by HCOOK/SiO2 modification for norfloxacin removal: Performance, DFT calculation and mechanism

As the main by-product of chemical pulping, lignosulfonate is mostly burned directly as fuel with low added value. Therefore, the conversion of lignosulfonate into multifunctional porous carbon materials is necessary for green sustainable development and practical applications. In this work, the pore size of sodium lignosulfonate-based porous carbons (LBCs) was regulated by green activator HCOOK and mesoporous manufacturing agent SiO 2 for the first time. The formation of micropores is beneficial to the improvement of surface area and adsorption performance, while the development of mesopores accelerates the mass transfer rate, but its adsorption performance is lower than that of micropores. The developed pore structure, sufficient oxygen content and graphene structure of LBCs lead to high adsorption performance for norfloxacin (NOR), reaching 341.9 mg g −1 . Characterization and Density functional theory (DFT) results show that the sorption process includes pore filling, π-π stacking, hydrogen bond and electrostatic interaction. In addition, pore volume and surface diffusion model (PVSDM) confirm that surface diffusion dominates the adsorption process. The above results provide an important reference value for the preparation and application of high-performance lignin-based adsorbents.