Showing papers on "Iron oxide published in 2021"

Revealing the activity of different iron carbides for Fischer-Tropsch synthesis

Abstract: Exploring the structure of iron-based catalysts on the catalytic performance of Fischer-Tropsch synthesis (FTS) reaction has attracted much attention. With this in mind, the mixture of SiO2 or Al2O3 powder and non-porous iron oxide powder (α-Fe2O3) have been investigated for understanding the nature role of different iron carbides in the FTS reaction by adjusting the formation of iron carbides. Under the typical FTS reaction conditions, the CO conversion of Al2O3/α-Fe2O3 = 1 catalyst could reach up to 61.6 %, which is about 3.3 times that of the pure α-Fe2O3 catalyst. Based on the characterization results, including in situ XPS and CO-DRIFTS as well as Mossbauer spectra, it is found that the electronic state of iron atoms is affected by the existence of SiO2 or Al2O3, and the interactions of Fe-Si or Fe-Al are formed on the surface of iron powder, which plays an important role in formation of C-rich iron carbide active phase (e-Fe2C). Although χ-Fe5C2 is usually as the active phase in the FTS reaction, we have found that the content of e-Fe2C is more positive to activity.

Adsorptive iron removal from groundwater

Abstract: Iron is commonly present in groundwater worldwide. The presence of iron in drinking water is not harmful to human health, however it is undesirable because of the associated aesthetic and operational problems, namely: bad taste, colour, stains on laundry and plumbing fixtures, and aftergrowth in the distribution system. Iron is generally removed from groundwater by the process of aeration followed by rapid sand fihration. This study reveals that two mechanisms are involved in this process, namely: "floc filtration" and "adsorptive filtration". Floc filtration comprises the oxidation of iron(ll), wbicb is the dominant form of iron in groundwater, to iron(lll) followed by floc formation and removal ofthe flocs by rapid sand filtration. In adsorptive fihration, iron(ll) is adsorbed onto filter media and subsequently oxidised to iron(lll), forming a coating on the filter media. Under the ommonly applied treatment conditions in iron removing plants the floc filtration is expected to be dominant and tbe adsorptive filtration complimentary. A pilot study conducted at the Gilze water treatment plant of Water Supply North West Brabant demonstrated that adsorptive filtration has several potential advantages over floc filtration, namely: longer filter runs due to slower head loss development, better fihrate quality, shorter ripening time and less backwash water use. In existing groundwater treatment plants, the high irondi) adsorption capacity ofthe iron oxide coated filter media makes it potentially possible to switch tbe goveming mode of operation from floc filtration to adsorptive filtration. To achieve this two options can be considered, they are: (i) iron(ll) adsorption under anoxic conditions followed by oxidation with oxygen-rich water and, (ii) adsorption of iron(ll) in the presence of oxygen and simultaneous oxidation. The first option might be attractive specifically when two filtration steps are available.

Drug delivery system based on magnetic iron oxide nanoparticles coated with (polyvinyl alcohol-zinc/aluminium-layered double hydroxide-sorafenib)

Abstract: The structural, physicochemical, morphological, and magnetic properties of magnetic drug nanoparticles prepared using polymer, layered double hydroxide (LDHs) and drug as the coating agent and magnetic iron oxide nanoparticles (MNPs) as the core were systematically studied. Firstly, a co-precipitation method was employed to synthesize the Fe3O4 nanoparticles. Then, the surface was coated with polyvinyl alcohol, Zn/Al-LDH and sorafenib (SO). XRD and FTIR studies indicate that the core has the crystal structure of the iron oxide. The TGA results supported the existence of both the core and the shell. The saturation magnetization of the as-synthesized Fe3O4 nanoparticles was found to be reduced from 80 to57 emu/g when the nanoparticles were coated with polyvinyl alcohol, Zn/Al-LDH and the drug sorafenib. HRTEM images revealed that the mean dimension of the naked Fe3O4 nanoparticles is around 30 nm. Further structural characterizations showed that the addition of the shell led to the formation of uniform particles with a particle size distribution of about 95 nm. The kinetics of drug release from the nanoparticles was found to be governed by the pseudo-second-order equation. Cell viability assays clearly showed that the magnetic iron oxide nanoparticles coated with polyvinyl alcohol-sorafenib-Zn/Al-layered double hydroxide were found to be more potent than sorafenib alone against HepG2 liver cancer cells, while displayed no cytotoxicity against 3T3 fibroblasts. These results show that the coated Fe3O4 magnetite nanoparticles are a good candidate as a drug delivery carrier to be further explored for biomedical applications.

Synergistically improved methane production from anaerobic wastewater treatment by iron/polyaniline composite

Abstract: The methane (CH4) production could be enhanced effectively by adding iron oxides and polyaniline (PANI) composite in anaerobic wastewater treatment. Synergic improvement on the methane production was observed in anaerobic system which was amended by the iron oxides/PANI composite. A total of ~530 mL of methane was produced from the anaerobic bio-system added composite, which was ~1.5 times of the sum of the systems added with the iron oxides and PANI. Then, the effect of the addition of the iron oxides/PANI composite on the degradation of organics, metabolism of the acetic acid, and the bio-electron transfer at the interface of composite was also investigated. The results showed that the iron oxide component in composite increases the activity of PTA enzymes to improve the production of acetic acid, thereby increase the methanogenesis by the acetoclastic methanogens. The PANI layer of the composites has a high bio-affinity, which makes the bio-electron transfer between the interface of electron-carrier and the material easier. Generally, the addition of iron oxides/PANI composite improved methanogenesis by the acetoclastic methanogens as well as improve the microbial extracellular electrons transfer at the interface of material.

Organ-specific toxicity of magnetic iron oxide-based nanoparticles.

Abstract: The unique properties of magnetic iron oxide nanoparticles determined their widespread use in medical applications, the food industry, textile industry, which in turn led to environmental pollution. These factors determine the long-term nature of the effect of iron oxide nanoparticles on the body. However, studies in the field of chronic nanotoxicology of magnetic iron particles are insufficient and scattered. Studies show that toxicity may be increased depending on oral and inhalation routes of administration rather than injection. The sensory nerve pathway can produce a number of specific effects not seen with other routes of administration. Organ systems showing potential toxic effects when injected with iron oxide nanoparticles include the nervous system, heart and lungs, the thyroid gland, and organs of the mononuclear phagocytic system (MPS). A special place is occupied by the reproductive system and the effect of nanoparticles on the health of the first and second generations of individuals exposed to the toxic effects of iron oxide nanoparticles. This knowledge should be taken into account for subsequent studies of the toxicity of iron oxide nanoparticles. Particular attention should be paid to tests conducted on animals with pathologies representing human chronic socially significant diseases. This part of preclinical studies is almost in its infancy but of great importance for further medical translation on nanomaterials to practice.

Recent advances in polymer-coated iron oxide nanoparticles as magnetic resonance imaging contrast agents

Abstract: The surface–chemically modified superparamagnetic iron oxide nanoparticles are broadly investigated as magnetic resonance imaging contrast agents based on their unique characteristics such as high magnetization values, diameter from 4 to 100 nm, and narrow distribution of particle size. However, naked nanoparticles might be easily oxidized by the air leading to loss of dispersibility and magnetization. Therefore, suitable surface coating strategies were developed to increase the stability of magnetic iron oxide contrast agents in the physiological conditions. In addition, the polymer-coated agents possess an improved biocompatibility in comparison with conventional agents. This review discusses important aspects of newly developed magnetic contrast agents such as chemical synthesis strategies, physical parameters, relaxivity parameters, the effect of various coatings, and emerging applications. Disadvantages associated with commercially available gadolinium contrast agents are considered, and the advantages of potential applications of iron oxide alternatives to traditional agents are presented. Finally, perspectives of the future developments, applications, and concerns of the magnetic nanoparticles are also included.

Iron oxide nanoparticles in biological systems: Antibacterial and toxicology perspective

Abstract: There has been an increasing number of studies in magnetic nanoparticles with auspicious applications in medicine. Among the oxides of magnetic nanoparticles, iron oxide has emerged as an indispensable tool in nanotechnology, particularly bio-nanotechnology. This is attributed to its exceptional properties such as size, shape, magnetism, and biocompatibility. In this review, iron oxide nanoparticles were exploited in different model organisms ranging from prokaryotes to eukaryotes, elucidating their cellular functions relative to their antibacterial activity, drug delivery, and toxicity.

Graphene Oxide/Fe 2 O 3 Nanocomposite as an Efficient Catalyst for Thermal Decomposition of Ammonium Perchlorate via the Vacuum-Freeze-Drying Method.

Abstract: The combination of graphene oxide (GO) and iron oxide (Fe2O3) may induce property enforcement and application extension. Herein, GO/Fe2O3 nanocomposites were synthesized via the vacuum-freeze-drying method and used for the thermal decomposition of ammonium perchlorate (AP). A series of characterization techniques were applied to elucidate the as-obtained nanomaterial's physicochemical properties. These results show that the treated GO is consistent with the pristine GO after the freeze-drying treatment. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses show that iron oxide nanoparticles are anchored on and between the GO sheets. The catalytical effect investigation on AP with different Fe2O3: GO ratios indicates that the high-temperature decomposition temperature of AP could be decreased by a temperature as high as 77 °C compared to pure AP accompanied by 3 wt % GO/Fe2O3 nanocomposite which proves the high catalytic performance of the nanocomposites. The first-principles calculation was employed to elaborate the synergistic effect, and the findings demonstrate that the presence of graphene in the catalyst can enhance the catalytic effect via reducing the activation energy barrier by ∼17% in the reaction of AP thermal decomposition.

Engineering shape anisotropy of Fe3O4-¿-Fe2O3 hollow nanoparticles for magnetic hyperthermia

Abstract: The use of microwave-assisted synthesis (in water) of α-Fe2O3 nanomaterials followed by their transformation onto iron oxide Fe3O4-γ-Fe2O3 hollow nanoparticles encoding well-defined sizes and shape...