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Conventional nanomaterials are met with the bottleneck problem of difficult recycling and reuse when applied to water treatment. Carbon aerogel with three-dimensional structure can effectively solve the problem of recycling, however, the preparation of efficient and recyclable aerogel catalyst is still an urgent technical problem. Here, an NH 2 -MIL-88B(Fe)/agarose carbon aerogel (MGA-x) was synthesized at different calcination temperatures (x = 100, 150, 200 and 300 °C) and their changes in structures and photo-electrochemical properties were investigated. As a photo-Fenton catalyst, the aerogel could efficiently activate H 2 O 2 to ultrafast degrade mitoxantrone in water. Within 2 min, the removal efficiency of mitoxantrone in the MGA-200/H 2 O 2 /Light system was 97.6%, which was 85.3 times greater than that in the agarose aerogel/H 2 O 2 /Light system. Notably, the aerogel catalyst could be directly recovered and recycled without additional treatments, and the microstructure and degradation performance were maintained even after five cycles, demonstrating excellent sustainability for applications in practical aquatic environment. The primary active radicals involved in the photocatalytic degradation process were • OH, h+ and • O 2 -, which were confirmed through free radical quenching experiments and electron paramagnetic resonance analysis. Additionally, possible degradation pathways for mitoxantrone were proposed based on the results of liquid chromatography-mass spectrometry. This study presents a photocatalytic aerogel with highly efficient degradation ability along with recycling and reuse capacity, exhibiting great potential for application in the remediation of water pollution. [Display omitted] • NH 2 -MIL-88B(Fe)/agarose carbon aerogel was prepared by low-temperature calcination. • The photo-Fenton reaction of MGA-200 through degrading MTX was studied. • The MGA-200/H 2 O 2 /Light system could ultrafast remove 97.6% of MTX in 2 min. • MGA-200 can be recovered and recycled directly without additional treatment. • A new pathway for the potential degradation of MTX was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Modified moxa ash, CNTs and agarose were used to synthesize biomass-based aerogels. • The prepared 2D aerogel membranes can swiftly filter out various contaminants. • The 3D aerogels exhibit excellent adsorption performance for antibiotics and dyes. • The 3D aerogels own good cyclical stability and reproducibility in water treatment. • Four main adsorption mechanisms of the aerogel for removing MTX was proposed. Powder adsorbents present limited recyclability when used for wastewater treatment. Bulk materials prepared via eco-friendly approaches typically exhibit excellent reproducibility over powders in terms of removing pollutants from aquatic environments. Here, biomass-based aerogels were synthesized via ball milling a mixture of modified moxa ash (a type of moxibustion waste), carbon nanotubes and ammonia, combined with agarose as biomolecule. The obtained aerogels display low density, high porosity, remarkable mechanical properties, and exceptional repeatability and stability for removing organic pollutants. By employing a two-dimensional (2D) aerogel membrane, pollutants such as 10 mg/L mitoxantrone (MTX), 5 mg/L methylene blue, 5 mg/L malachite green, or 5 mg/L rhodamine B could be dynamically adsorbed and swiftly filtered out, achieving nearly 100 % of the removal rate. For three-dimensional (3D) aerogels, efficient removals of MTX (98.4 % at 135 min) and cationic dyes under various conditions were observed, in which the adsorption capacity reached 28.23 mg/g for low concentration of MTX at 120 min. After four cycles, the aerogel still retained 93 % of its original capacity and the removal rate was still 92.4 %. The adsorption process obeys second-order kinetics and adheres to the Freundlich and Temkin isotherm models. Furthermore, the primary mechanism by which the aerogels adsorb MTX includes pore filling, electrostatic interactions, π-π conjugation and hydrogen bonding. The adsorption mechanism was better explained by the results of density functional theory. Biomass-based 2D/3D aerogels are promising, low-cost, eco-friendly and highly efficient absorbents for mitigating wastewater contamination. [ABSTRACT FROM AUTHOR]