Adsorption Behaviour and Mechanism Analysis of Food Waste‐Derived Magnetic Biochar on Anionic Dyes

Abstract Food waste (FW), a major component of municipal solid waste (MSW), has a high volume but low resource utilization, posing a significant challenge in waste management. In this study, magnetic Fe 3 O 4 −modified food waste‐derived biochar (Fe 3 O 4 /FWB) was synthesized via a one‐step solvothermal method for the removal of the anionic dye Coomassie Brilliant Blue (CBB). Single factor experiments followed by response surface methodology (RSM) optimization identified optimal conditions: pH 6.14, temperature 23.85 °C, adsorbent dose 0.06 g, and initial CBB concentration 35.20 mg/L, achieving 97.02% removal within 60 minutes. SEM analysis confirmed the preservation of spherical morphology. BET analysis revealed a mesoporous structure with an average pore size of 4.31 nm and specific surface area of 51.96 m 2 /g, enhancing adsorption capacity. XRD confirmed the crystalline Fe 3 O 4 structure. Adsorption kinetics followed a pseudo‐second‐order model ( R 2 = 0.99953), while the Freundlich model ( R 2 = 0.90854) indicated multilayer chemisorption. Zeta potential and FTIR analyses revealed that electrostatic attraction, coordination, and hydrogen bonding were dominant in the adsorption process. This work provides efficient, sustainable material for dye wastewater treatment and expands the potential for organic solid waste valorization.