Green-synthesized CO@FeNPs: a dual-functional catalyst for rapid dye degradation and antibacterial action.

The green synthesis of iron nanoparticles by Crassula ovata (CO) extract (CO@FeNPs) and their photocatalytic degradation of methyl orange (MO) dye has been described in this study. The formation of nanoparticles was ensured by UV-Visible spectroscopy with a distinct peak at 261 nm. The EDX asserted the existence of C, O, Cl, K, Ca, and Fe. XRD analysis established the polycrystalline nature of CO@FeNPs, with both metallic α-Fe and magnetite (Fe₃O₄) phases, which indicated a core-shell structure. Photocatalytic experiments revealed 94% dye degradation of MO within 50 min in the presence of sunlight having catalyst dosage of 0.4 g/l with MO dye of an initial concentration of 30 mg/l. Kinetic experiments revealed that the pseudo-second-order model fits best in the adsorption process (R2 = 0.996). Scavenger experiments revealed hydroxyl radicals, superoxide ions, and electrons as predominant reactive species in dye degradation, with negligible contribution from holes. Reusability experiments proved the stability of the catalyst, which retained 90% activity after five cycles. In addition to photocatalytic performance, the synthesized CO@FeNPs exhibited promising antibacterial activity against both Escherichia coli and Staphylococcus aureus. Importantly, this work directly aligns with Sustainable Development Goal 6 (Clean Water and Sanitation) by offering an eco-friendly and effective solution for wastewater purification and microbial control.