Evolution of Waste Iron Rust into Magnetically Separable g‑C3N4–Fe2O3 Photocatalyst: An Efficient and Economical Waste Management Approach

The corrosion of iron structures gives rise to serious safety, environmental pollution, and economic issues. However, current technologies are neither efficient to impede the corrosion completely nor effective in the recycling of waste iron rust. To best recycle of waste iron rust, we report a simple, cost-free, and sustainable strategy to exploit iron rust as a Fe-precursor for the synthesis of magnetic Fe2O3 nanoparticles (NPs) via simple grinding and calcination process. The process efficiently transforms bulky iron rust into ferromagnetic Fe2O3 NPs, which exist in both α and γ phases. Synthesized materials were characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, and vibrating sample magnetometer. We also explored the catalytic ability of rust-derived Fe2O3 as a low-cost material for the fabrication of magnetically separable g-C3N4–Fe2O3 composite as a photocatalyst. It is interesting to find that the g-C3N4–Fe2O3 composite exhibited superior photocatalytic activity than that of individual g-C3N4 and Fe2O3 under sunlight toward Methyl Orange and Textile Effluent. Moreover, the g-C3N4–Fe2O3 composite exhibited excellent reusability without loss of photocatalytic activity after successive five runs, and more importantly, photocatalyst could be recovered magnetically. The histological studies on the gills of freshwater fish Tilapia revealed that toxic dye solution induced damage to secondary gill lamellae, whereas the photodegraded products were found to less toxic and did not cause any structural alteration in the gill architecture. This innovative process of waste recycling offers a cost-free and large-scale approach to transform waste iron rust into magnetically separable Fe-based photocatalyst for environmental remediation.