Competing reactions of selected atmospheric gases on Fe₃O₄nanoparticles surfaces

Abstract

Heterogeneous reactions on atmospheric aerosol surfaces are increasingly considered important in understanding aerosol-cloud nucleation and climate change. To understand potential reactions in polluted atmospheres, the co-adsorption of NO2 and toluene to magnetite (Fe3O4i.e. FeO·Fe2O3) nanoparticles at ambient conditions was investigated for the first time. The surface area, size distribution, and morphology of Fe3O4 nanoparticles were characterized by BET method and high-resolution transmission electron microscopy. Adsorption isotherms, collected by gas chromatography with flame ionization detection, showed that the presence of NO2 decreased the adsorption of toluene. The analyses of the surface chemical composition of Fe3O4 by X-ray photoelectron spectroscopy (XPS) reveal that, upon the addition of NO2, the surface is oxidized and a contribution at 532.5 ± 0.4 eV in the O1s spectrum appears, showing that NO2 likely competes with toluene by dissociating on Fe(2+) sites and forming NO3(-). Different competing effects were observed for oxidized Fe3O4; oxidation occurred when exposed solely to NO2, whereas, the mixture of toluene and NO2 resulted in a reduction of the surface i.e. increased Fe(2+)/Fe(3+). Analyses by time of flight secondary ion mass spectrometry further suggest toluene reacts with Fe(3+) sites forming oxygenated organics. Our results indicate that on reduced magnetite, NO2 is more reactive and competes with toluene; in contrast, on oxidized Fe3O4, toluene is more reactive. Because magnetite can assume a range of oxidation ratios in the environment, different competing interactions between pollutants like NO2 and toluene could influence atmospheric processes, namely, the formation of Fe(2+) and the formation of atmospheric oxidants.

Utilizing Waste Thermocol Sheets and Rusted Iron Wires to Fabricate Carbon–Fe3O4 Nanocomposite‐Based Supercapacitors: Turning Wastes into Value‐Added Materials

“…The core-levelF e2ps pectrum can be deconvoluted into two groups of Fe speciest hat are characteristic of ChemSusChem 2018ChemSusChem , 11,2410ChemSusChem -2420 www.chemsuschem.org Fe 2 + and Fe 3 + ,a nd two weak satellite-type peaks (identified as "Sat."). [35,36] As shown in Figure 3e,t he core level O1ss pectrum can be deconvoluted into four peaks at 533.1 (CÀO), 532.2 (CÀOÀC), 531.5 (FeÀOÀC), and 530.0 eV (FeÀO). [35,36] As shown in Figure 3e,t he core level O1ss pectrum can be deconvoluted into four peaks at 533.1 (CÀO), 532.2 (CÀOÀC), 531.5 (FeÀOÀC), and 530.0 eV (FeÀO).…”

“…The fitting peaks at binding energies of 710.3 and 724.1 eV are indexed to Fe 2 + ,w hile peaks situated at 712.2, 715.1, 725.2, and 728.9 eV are due to Fe 3 + . [35,36] As shown in Figure 3e,t he core level O1ss pectrum can be deconvoluted into four peaks at 533.1 (CÀO), 532.2 (CÀOÀC), 531.5 (FeÀOÀC), and 530.0 eV (FeÀO). [37] It can be inferred that Fe-O-C is formed between the Fe 3 O 4 nanoparticles and carbon.…”

An Initial Evaluation on the Adsorption of SO2 and NO2 over Porous Fe3O4 Nanoparticles Synthesized by Facile Scalable Method

“…e adsorption of NO 2 at room temperature leads to an intensity increase of the 1386 cm −1 band, corresponding to the band of nitrate (NO 3 − ) [26]. e adsorption mechanism of NO 2 on the Fe 3 O 4 surface was reported by Eltouny et al [27] via the following equations: 2NO 2 (gas) ⟶ 2NO 2 (adsorbed)…”

Highly monodispersed hematite cubes for removal of ionic dyes

“…exposed to H 2 O, the peaks may be ascribed to chemisorbed oxygen and hydroxyl groups at nonequivalent sites [44,45]. They indicated at pressures as low as 10 -4 Torr, hydroxyl groups can form due to the dissociation of moisture and strongly adjoin on the magnetite surface.…”