Magnetite Nanoparticles Loaded into Halloysite Nanotubes for Arsenic(V) Removal from Water

Abstract

Groundwater contaminated by arsenic (As) is a serious concern because it poses a significant threat to millions of people reliant on both drinking and irrigation of farms. Hence, the low-cost and efficient treatment of these waters is of utmost importance. This study presents the ecofriendly synthesis of magnetite nanoparticles (Fe3O4 NPs)-immobilized halloysite nanotube (HNT) composite (Fe3O4@HNT) for remediating arsenate [As­(V)] from water. High-resolution transmission electron microscopy confirmed that ultrasmall Fe3O4 NPs (4.52 ± 1.63 nm) were immobilized on the interior surface of HNT. Fe3O4@HNT possesses a larger surface area (82 ± 0.23 m2/g) and a higher thermal stability (7.1% weight loss at 950 °C) than a pristine HNT (47.23 ± 0.14 m2/g and 12.6%, respectively). Adsorption kinetics were best fitted with pseudo-second-order and intraparticle diffusion, while the isotherms results were best supported with the Freundlich model (R 2 = 0.99 in each case). Therefore, it could be surmised that multiphase rate-controlling chemisorption occurred during adsorption. The thermodynamics data revealed the endothermic nature of As­(V) adsorption by Fe3O4@HNT. Fourier transform infrared and X-ray photelectron spectroscopy analyses confirmed chemical bonding between As and Fe. In addition, Fe3O4@HNT was easily separable by an external magnet (the saturation magnetization value was 20 emu/g), which is an additional benefit of the material to be used on an industrial scale. The material was also reusable after regeneration for five rounds of consecutive sorption–desorption with excellent efficiency and no substantial loss of structural integrity. Furthermore, Fe3O4@HNT removed more than 99% As­(V) from the groundwater, signifying its viability in real-case implementation. Cost-benefit analysis ensured that Fe3O4@HNT was cost-effective, while its biocompatibility test confirmed no detrimental impact on soil bacterial growth once the spent material had been disposed. Consequently, cheap, easily separable, reusable, and biocompatible Fe3O4@HNT may be a prospective composite for the sustainable eradication of As and other metallic toxicants from wastewater.

Microporous Hematite-Loaded Composite Membrane for Arsenic(III) and Arsenic(V) Removal

“…34 A strategy of immobilizing iron-based nanoparticles in porous support can create better contact and result in higher reactivity, better dispersion of nanoparticles, and eventually higher sorption capacity with reduced release to water. 34,48 Further, immobilization in nanoscale pores enhances mass transfer significantly. 49 From the water treatment perspective, combining adsorption and membrane filtration is possible.…”

“…Nanostructured adsorbents, such as hematite, tend to aggregate in solution, which decreases the adsorption . A strategy of immobilizing iron-based nanoparticles in porous support can create better contact and result in higher reactivity, better dispersion of nanoparticles, and eventually higher sorption capacity with reduced release to water. , Further, immobilization in nanoscale pores enhances mass transfer significantly . From the water treatment perspective, combining adsorption and membrane filtration is possible. , Microfiltration (MF) and ultrafiltration (UF) membranes offer a wide range of pore sizes from 1 nm to 1 μm for (nano)­particle retention , and consequently are attractive substrates that can achieve partial (MF) or full (UF) physical disinfection …”

Morphology-Controlled Green Synthesis of Magnetic Nanoparticles Using Extracts of ‘Hairy’ Roots: Environmental Application and Toxicity Evaluation

“…In addition, nutrients can be recovered and pollutants can be detected in waste effluents using magnetic nanoparticles. Generally, Fe(III)-based hydroxides and corresponding oxides (ferrihydrite, goethite, feroxyhyte and hematite) attract special attention owing to their heavy metals adsorption performance in oxy-type and the convenience of magnetic separation [ 10 ]. The binding of arsenic with Fe(III)-(hydr)oxides is strongly determined by the type of formed surface complexes and the presence of competitive ions in the solution (for example, phosphate) [ 11 , 12 ].…”

ACS Applied Nano Materials Australia Forum

“…The implementations of nanomaterials as viable candidates for water purification, pollutant removal and for anti-bacterial applications are the foci of three studies in this collection. Deb et al from the University of Newcastle introduced magnetite nanoparticles loaded into halloysite nanotubes for arsenic removal from water . Whereas, in a multidisciplinary collaboration between universities and institutions from South Australia, including the University of South Australia and the University of Adelaide, the authors utilized hydrothermal etching to engineer spikelike nanostructures on titanium substrates for the treatment of anaerobic dental pathogens .…”

“…Deb et al from the University of Newcastle introduced magnetite nanoparticles loaded into halloysite nanotubes for arsenic removal from water. 6 Whereas, in a multidisciplinary collaboration between universities and institutions from South Australia, including the University of South Australia and the University of Adelaide, the authors utilized hydrothermal etching to engineer spikelike nanostructures on titanium substrates for the treatment of anaerobic dental pathogens. 7 In another work led by the University of Adelaide, Zhong et al developed cathodes based on FeOCl nanoparticles decorated on oxygen-enriched carbon nanotubes for the electro-Fenton degradation of pollutants.…”