Sustainable degradation of azo dyes using Foeniculum vulgare seed extract-derived zinc oxide nanoparticles

This study addresses the critical environmental issues of water scarcity and textile industry pollution, particularly from azo dyes. Recognizing the limitations of traditional wastewater treatment methods, the research explores a novel and sustainable approach: synthesizing zinc oxide nanoparticles (ZnO NPs) using Foeniculum vulgare (fennel seed) extract for azo dye degradation. The study employs various characterization techniques to analyse the synthesized ZnO NPs: X-ray diffraction (XRD): Confirms the successful formation of pure ZnO NPs with an average crystallite size of 35.88 nm. UV-visible spectroscopy: determines the band gap energy of the NPs to be 3.59 eV, a crucial factor in their photocatalytic activity for dye degradation. Fourier transform infrared spectroscopy (FT-IR): reveals the presence of functional groups in both the fennel seed extract and the ZnO NPs, suggesting the successful incorporation of biomolecules from the extract during synthesis. This incorporation may influence the photocatalytic properties. Field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX): Confirm the physical morphology and elemental composition of the NPs. The elemental map visualizes the distribution of zinc and oxygen within the particles. High-resolution transmission electron microscopy (HR-TEM) confirms the formation of multi-structured in ZnO. The catalytic performance is evaluated by examining the degradation of commercial Methyl Orange. At a dose of 120 mg L-¹, FV/ZnO (dosage of 250 mg L-¹) had a removal effectiveness of around 97%. The photodegradation process follows a pseudo-first-order kinetics paradigm.