Sustainable Fenton-like degradation of methylene blue over MnO₂-loaded poly(amidoxime-hydroxamic acid) cellulose...

Catalysts based on cellulose/metal oxide hybrids are considered effective for the remediation of dye wastewater. However, the difficult recovery of commonly used nanocellulose and the weak binding strength of metal oxide nanoparticles restrict their wide application. Herein, MnO₂ nanoparticle-loaded poly(amidoxime-hydroxamic acid) modified microcrystalline cellulose (pAHA-MCC@MnO₂) catalysts were synthesized via an oximation reaction followed by in-situ growth. Morphology, crystallinity and textural characteristics of pAHA-MCC before and after deposition of MnO₂ nanoparticles were characterized by SEM, EDS, FTIR, XRD and XPS analyses. The main results indicated the formation of hierarchical porous structured cellulose microrods with uniform distribution of hydrangea flower-like MnO₂ nanoparticles. In the presence of H₂O₂, pAHA-MCC@MnO₂ displayed good catalytic performance toward the degradation of methylene blue (MB) over a wide pH range of 3-10, due to the advanced Fenton-like catalysis. Reaction conditions, such as amount of H₂O₂ used, the initial MB concentration and catalyst dosage were also investigated. The optimized system showed 97.6% removal of MB in 25 min for 100 mg/L MB solution, with very little decrease in performance after 5 cycles. This work provides a facile and promising strategy for the development of biodegradable and sustainable architectures capable of efficiently degrading dye wastewater.