Synergistic interfacial effects in tea-waste derived magnetic nanobiochar/ CeO2 for selective degradation of Rhodamine B: Kinetic modeling and pathway analysis

초록

Conversion of waste biomass into nanobiochar-based photocatalyst offers a sustainable route for addressing wastewater pollution caused by persistent organic dye. In this study, a green-synthesized Fe2O3/NBC/CeO2 (FNBC) catalyst was developed using tea-waste biomass-derived nanobiochar as support for the fabrication of Fe2O3 and CeO2 nanoparticles, aimed at the efficient photocatalytic degradation of Rhodamine B (RhB) under visible light. Comprehensive characterizations were examined to confirmed the successful formation of catalyst. The catalyst had bigger surface area (54.947 m2 g/L) and mesopores (7.8 nm), with optical band gap of 2.93 eV. XPS analysis showed the co-existence of Fe3+/Fe2+ and Ce4+/Ce3+ oxidation states. Under UV irradiations, the FNBC catalyst (25 mg/L) exhibited excellent photocatalytic activity towards RhB, achieving 96.4 % degradation at pH 11 within 120 min by following first-order kinetics model (k = 0.031 min-1). Moreover, the catalyst shows excellent stability and reusability, retaining high photocatalytic efficiency even after the fifth reuse cycle following magnetic recovery. Reactive oxygen species (ROS) scavenging studies further confirmed that the center dot OH played a dominant role in the degradation mechanism of RhB. Further, GC-MS analysis of the degraded products confirmed effective dye mineralization without the formation of harmful intermediate compounds, highlighting the environmental safety of the process. Overall, this study demonstrates an effective waste-to-wastewater treatment strategy, where tea waste is valorised into a highly efficient, stable, and eco-friendly photocatalyst for sustainable wastewater remediation.

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