H₂O₂-Free Sunlight-Promoted Photo-Fenton-Type Removal of Hexavalent Chromium Using Reduced Iron Oxide Dust

Abstract

Herein, we explored a simple approach to using readily available low-cost industrial waste from steel industries known as red-colored iron oxide dust (IOD). After that, it was used for the sunlight-assisted photo removal of another toxic waste material (hexavalent chromium (Cr(VI)) from the aqueous medium showing the photo-Fenton-type mechanism, importantly without using hydrogen peroxide. The photoactive properties of chemically reduced IOD (r-IOD) have been explored to remove toxic Cr(VI) in the presence of two different sources of light (sunlight and artificial bulb light). Kinetic studies and various control experiments have been performed to check the comparative photocatalytic performance of IOD versus r-IOD nanoparticles. The values of the half-life of Cr(VI) removal strongly support the significant influence of the sun on the faster rate for the removal of ∼250 mg L −1 Cr(VI). To maintain the lower pH needed for Cr(VI) reduction, a small quantity of formic acid was used, which can be removed easily by forming CO 2 and H 2 O. The radical trapping experiments and spectroscopic investigations of residue products obtained after the photoreduction process have been explored to support the mechanistic investigation involved in the sunlight-promoted photoreduction of Cr(VI).

Waste-Derived Iron Nanoparticles for Solvent-Free Single-Step Reductive Acetylation of Nitroarenes

“…Concerning the same, we proposed a simpler methodology which could utilize magnetic iron dust/powder produced while cutting or grinding the iron rods/objects. As magnetically separable iron-based nanoparticles could be a significant and sustainable approach − for the proper utilization of discarded material into valuable nanomaterials. , …”

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

“…The fabrication of magnetic, photoactive r-IOD nanoparticles from IOD has been carried out via single-step chemical-based reduction methodology as described earlier . Briefly, IOD was treated with sodium borohydride (NaBH 4 ) in a (1:1) mixture of MeOH and water.…”

“…On deconvolution of Fe 2p short scan, the existence of Fe(0), Fe 2p3/2 (II), Fe 2p3/2 (III), Fe 2p3/2 (satellite), Fe 2p1/2 (II), Fe 2p1/2 (III), and Fe 2p1/2 (satellite) was discovered at ∼706.9, ∼709.1, ∼709.8, ∼711.4, ∼715.3, ∼720.1, ∼723.2, and ∼728.2 eV, respectively (Figure b) . Some Fe (III) ions were reduced to Fe­(II), which led to the construction of Fe 3 O 4 (FeO + Fe 2 O 3 ), including a relatively small amount of oxygen as compared to IOD . The deconvoluted O 1s short scan of r-IOD showed three peaks at ∼530.2, ∼531.3, and ∼532.5 eV, which correspond to Fe–O (Figure c).…”

Fe3O4 Nanoparticles Synthesized from Waste Iron Dust for Sunlight-Boosted Photodegradation of Nitrophenols and Their Mixtures

“…Of them, magnetite (Fe 3 O 4 ) as a heterogeneous catalyst has always been advantageous as it can be easily magnetically separated from the solution. , Thus, the simple and viable synthesis of inverse spinel of Fe 3 O 4 at low cost and its use for the removal/degradation/photodegradation of complex toxic organic moieties in wastewater are significant areas of research interest . For the same, pickled red-iron-oxide dust (IOD), which is generally discarded as an unused byproduct, can be used to produce various iron-based catalysts. , Thus, the synthesis of low-cost heterogeneous iron catalysts possessing photo-Fenton-type properties is the need of the present time and needs scientific concern for using them in wastewater treatment and some other applications …”