Valorization of Passiflora edulis Peel for the Fabrication of Recyclable Nanosilver/Ceria-Cellulose Aerogels for Efficient Catalytic Reduction of Methyl Orange

Developing fully sustainable and recyclable catalysts from agricultural waste remains a major challenge for advanced wastewater treatment. Herein, we report an integrated, zero-waste strategy to fabricate a hierarchically structured Ag/ceria-cellulose porous catalyst derived exclusively from purple Passiflora edulis peel waste. Phytochemical-rich peel extracts were employed as green reducing and stabilizing agents for the in situ synthesis of Ag nanoparticles, while the residual cellulose-rich biomass was converted into a three-dimensional porous aerogel via microwave-assisted extraction and freeze-drying. Incorporation of ceria nanorods endowed the aerogel with abundant oxygen vacancies and strong metal–support interactions, effectively suppressing Ag nanoparticle agglomeration and promoting interfacial electron transfer. The optimized Ag/ceria-cellulose aerogel exhibited uniformly dispersed Ag nanoparticles with an average size of 7.84 nm. Under mild conditions (0.5 wt% Ag loading, catalyst dosage of 0.5 g L −1 , and MO/NaBH 4 molar ratio of 1/200), over 95% of methyl orange was reduced within 30 min, following pseudo-first-order kinetics with an apparent rate constant of 0.14 min −1 . Owing to its monolithic and mechanically robust architecture, the aerogel catalyst could be readily recovered by simple filtration and retained more than 75% of its initial activity after five consecutive cycles. The superior catalytic performance and durability originate from the synergistic interplay between Ag nanoparticles, oxygen vacancy-rich ceria nanorods, and the interconnected cellulose aerogel matrix, which collectively enhance active-site accessibility, charge transfer efficiency, and structural stability. This work demonstrates a scalable and circular pathway for transforming passion fruit peel waste into high-value, reusable catalysts for wastewater remediation.