Magnetic-Transition-Metal Oxides Modified Pollen-Derived Porous Carbon for Enhanced Absorption Performance

In our work, the transition-metal-oxide precursor (TMO@BC, M = Fe, Co, Ni) has been loaded on the pollen carbon by the hydrothermal method and annealed at different temperatures to generate a composite material of metal oxide and pollen carbon in this study, which can effectively prevent agglomeration caused by a small size and magnetism. The XRD patterns of the samples showed that the as-synthesized metal oxides were γ-Fe₂O₃, CoO, and NiO. In the 20 mg/L methyl orange adsorption experiment, the adsorption amount of CoO@C at 500 ℃ reached 19.32 mg/g and the removal rate was 96.61%. Therefore, CoO@C was selected for the adsorption correlation-model-fitting analysis, which was in line with the secondary reaction. The pseudo-second-order kinetic model (R²: 0.9683-0.9964), the intraparticle diffusion model, and the Freundlich adsorption isotherm model indicated that the adsorption process was the result of both physical and chemical adsorptions, and the judgment was based on the electrostatic action. The adsorption and removal efficiency of ciprofloxacin (CIP) by changing the pH of the reaction was about 80%, so the electrostatic attraction worked, but not the main factor. Recovered by an external magnetic field, the three-time recycling efficiency was still maintained at more than 80%. This novel biomass-derived magnetic porous carbon material embedded with transition-metal-oxide nanoparticles is highly promising for many applications, especially in the field of environmental remediation.