Low Temperature Processing of Iron Oxide Nanoflakes from Red Mud Extract toward Favorable De-arsenification of Water

Abstract

Iron oxide (α-Fe2O3) was synthesized from red mud extract followed by hydrothermal reaction at 150 °C/6–24 h in the presence of NH4OH. The crystallinity of α-Fe2O3 increased with reaction time as confirmed by X-ray Diffraction, while Fourier transform infrared spectroscopy and Raman illustrate the symmetric stretching vibration of the Fe–O bond in α-Fe2O3. The X-ray photoelectron spectroscopic analysis shows O 1s spectra at 530.6, 531.2, and 532 eV, signifying the lattice oxygen in Fe–O, surface oxygen defects, and oxygen in adsorbed hydroxyl groups, respectively. The morphology of α-Fe2O3 nanoflakes was noticed from field emission scanning electron microscopy and transmission electron microscopy. The developed particles reveal the BET surface area in the range of 136–347 m2/g. The maximum As­(V) adsorption capacity of 32–41 mg/g was obtained for adsorbent dose of 0.25 g/L. The arsenic level could be lowered down to 2–3 μg/L (<10 μg/L as per WHO’s limit) with contaminated real water (64 μg/L) using 0.25 g/L of sample dose within 5 min of adsorption.

Visible light induced photocatalytic removal of an organic dye using metal doped iron oxide based catalysts derived from red mud

“…The iron in red mud was extracted as reported earlier in our previous work. 37 In brief, the extraction of Fe( iii ) from red mud (RM) involved leaching of 40 g of crushed RM powder with 400 mL of 6(M) HCl under reflux conditions at 90 °C for 3 h. In order to synthesize an iron oxide-based adsorbent, the requisite amount of tetra propyl ammonium hydroxide solution was added dropwise into 10 mL of RM extract under stirring for 30 min, maintaining a pH of 8–9. The as-generated brown solid mass was placed into a hydrothermal autoclave lined with Teflon followed by heating at 150 °C/24 h. The reddish brown product was collected by repeated centrifugation and washing followed by drying at 60 °C/6 h. The prepared sample was designated as FETP.…”

Recent Advancements in the Field of Chitosan/Cellulose-Based Nanocomposites for Maximizing Arsenic Removal from Aqueous Environment

“…Incorporating size control in metal oxides, particularly zerovalent iron particles, further enhances their performance in arsenic removal. This improvement can be attributed to several distinctive advantages, including high specific surface area, reactivity, specificity, and shortened intraparticle diffusion pathways. − On small size scales, adsorbent materials exhibit numerous exposed sites due to their large specific surface area, resulting in significantly shorter removal times compared to their bulk form counterparts. , However, despite the proven efficiency of natural adsorbents in arsenic adsorption, practical field applications are often limited due to the presence of interfering ions or complex water systems. Nonetheless, the strong chemical affinity between the adsorbent and arsenic can mitigate the complexity of the environment, thereby providing a specialized adsorbent with dynamic applicability …”