Sustainable NH2-MIL-88B(Fe)/agarose carbon aerogel as a photo-Fenton catalyst for ultrafast degrading mitoxantrone

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 NH2-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 H2O2 to ultrafast degrade mitoxantrone in water. Within 2 min, the removal efficiency of mitoxantrone in the MGA-200/H2O2/Light system was 97.6%, which was 85.3 times greater than that in the agarose aerogel/H2O2/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 •O2-, 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.