Magnetite nanoparticles decorated on cellulose aerogel for p-nitrophenol Fenton degradation: Effects of the active phase loading, cross-linker agent and preparation method

Magnetite nanoparticles (Fe₃O₄ NPs) are among the most effective Fenton-Like heterogeneous catalysts for degrading environmental contaminants. However, Fe₃O₄ NPs aggregate easily and have poor dispersion stability because of their magnetic properties, which seriously decrease their catalytic efficiency. In this study, a novel environmentally friendly method for synthesising Fe₃O₄@CA was proposed. Fe₃O₄ NPs were immobilized on the 3D cellulose aerogels (CAs) in order to augment the degradation efficiency of p-nitrophenol (PNP) treatment and make the separation of the catalyst accessible by vacuum filtration method. Besides, CAs were fabricated from a cellulose source extracted from water hyacinth by using different cross-linking agents, such as kymene (KM) and polyvinyl alcohol-glutaraldehyde system (PVA-GA), and other drying methods, including vacuum thermal drying and freeze drying, were evaluated in the synthesis process. As-synthesized samples were analysed by various methods, including Powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and Brunauer-Emmett-Teller. Then, using ultraviolet-visible spectroscopy, the difference in the degradability of PNP of the obtained material samples was also investigated to determine their potential applications. Results highlighted that the Fe₃O₄-3@CA-KF catalyst with an Fe₃O₄ loading of 0.40 g/g_CA used KM as a cross-linker and the freeze-drying method demonstrated the highest PNP removal efficiency (92.5 %) in all Fe₃O₄@CA samples with a H₂O₂ content of 5 g/L. The degradation kinetics and well-fitted pseudo-first-order model were investigated. Notably, after five successive PNP degradation experiments, this catalyst retained ∼80 % of the ability to degrade PNP, indicating its outstanding reusability. In environmental remediation, this study provides valuable insights into the development of simply separated and high-efficiency catalysts for heterogeneous catalytic reactions.