Photoactive Fe₃O₄@Fe₂O₃ Synthesized from Industrial Iron Oxide Dust for Fenton-Free Degradation of Multiple Organic Dyes

Herein, we described a cost-effective, viable methodology for using an iron-based industrial waste material known as iron oxide dust (IOD), also known as Hematite (α-Fe₂O₃) for the synthesis of their chemically reduced magnetic version named r-IOD (Fe₃O₄@α-Fe₂O₃). r-IOD showed its visible-light-promoted photoresponsive behavior for the photodegradation of higher concentration (∼1000 mg L^-1) of five different model dyes (methyl orange (MO), metanil yellow (MY), Congo red (CR), methylene blue (MB), crystal violet (CV), and their mixtures) in the presence of sunlight. Based on kinetic and radical trapping experiments, mechanistic analysis supports the significant involvement of superoxide radicals responsible for the photodegradation. Moreover, different industrial and soil samples were externally spiked with dyes and further analyzed for a similar set of photodegradation experiments to support the viability of the reported procedure, concerning the utilization of waste materials.