Presence Of Iron Oxide Particles Research Articles

Presence of iron oxide particles can reduce the cake fouling in UF systems

Ultrafiltration (UF) has been widely used in drinking water treatment. However, the deposition of iron oxide particles on the membrane surface facilitates the formation of cake layers, which limits the application of UF in iron-bearing water treatment. To understand the impact of iron oxides on the membrane fouling of UF, the effects of iron oxide particles on the bio-regulated cake layer and conventional cake layer formed at the flux of 5 and 20 L·m−2·h−1 were investigated, and compared with SiO2 particles. Unlike the SiO2 paticles which tends to increase the cake fouling resistance, iron oxide paticles could significantly reduce the cake fouling resistance. The iron oxide-UF could reduce specific resistance by 65 %～75 % in bio-regulated cake layer and 40%～50% in conventional cake layer. OCT observations revealed that in the presence of iron oxide, the thickness of the conventional cake layer increased significantly, while the thickness of the bio-regulated cake layer remains unchanged. Therefore, the increased resistance was primarily attributed to the formation of a porous cake layer, which could be evidenced by SEM images. Besides, in the presence of iron oxide, the content of polysaccharides and proteins in the cake layer decreased. Particularly, for the bio-regulated cake layer, the content of polysaccharides and proteins decreased by 80.0% and 59.9%, respectively. This may be attributed to the capability of iron oxide to mitigate microbial-induced fouling and selectively adsorb macromolecular organic matters. Consequently, iron oxide exhibits distinct properties compared to traditional particles in mitigating cake fouling. Retaining some iron oxide before UF could facilitate the mitigation of membrane fouling in iron-bearing water treatment

Magnetic Mesoporous Silica for Targeted Drug Delivery of Chloroquine: Synthesis, Characterization, and In Vitro Evaluation.

Malaria is a dangerous tropical disease, with high morbidity in developing countries. The responsible parasite has developed resistance to the existing drugs; therefore, new drug delivery systems are being studied to increase efficacy by targeting hemozoin, a parasite paramagnetic metabolite. Herein, magnetic mesoporous silica (magMCM) was synthesized using iron oxide particles dispersed in the silica structure for magnetically driven behavior. The X-ray diffractogram (XRD) and Mössbauer spectra show patterns corresponding to magnetite and maghemite. Furthermore, Mössbauer spectroscopy revealed superparamagnetic behavior, attributed to single magnetic domains in particles smaller than 10 nm. Even in the presence of iron oxide particles, the hexagonal structure of MCM is clearly identified in XRD (low-angle region) and the channels are visible in TEM images. The drug chloroquine (CQ) was encapsulated by incipient wetness impregnation (magMCM-CQ). The N2 adsorption-desorption isotherms show that CQ molecules were encapsulated in the pores, without completely filling the mesopores. BET surface area values were 630 m2 g-1 (magMCM) and 467 m2 g-1 (magMCM-CQ). Encapsulated CQ exhibited rapid delivery (99% in 3 h) in buffer medium and improved solubility compared to the non-encapsulated drug, attributed to CQ encapsulation in amorphous form. The biocompatibility assessment of magMCM, magMCM-CQ, and CQ against MRC5 non-tumoral lung fibroblasts using the MTT assay after 24 h revealed no toxicity associated with magMCM. On the other hand, the non-encapsulated CQ and magMCM-CQ exhibited comparable dose-response activity, indicating a similar cytotoxic effect.

Harvesting of Microalgae from Synthetic Fertilizer Wastewater by Magnetic Particles Through Embedding–Flocculation Strategy

Microalgae bio-treatment of synthetic fertilizer wastewater is particularly attractive due to their photosynthetic capabilities. Microalgae tend to convert solar energy into useful biomass, incorporating with the nutrients that present in wastewater, such as nitrogen and phosphorus. However, harvesting of microalgae remains a challenge because of the small size (3–30 μm) of microalgae cells and the repulsion between the negatively charged microalgae cells maintains a stable cell suspension. Magnetic-aided-embedding-flocculation strategy, which is one-step method by mixing microalgae, magnetic particles and flocculant together, is proposed for microalgae harvesting in order to meet cost and time effectiveness. In this study, the optimum cell separation efficiency of Chlorella vulgaris microalgae above 96% at 5 mg/L of chitosan dosage is achieved. With the aid of iron oxide particles, either micro- or nano-size, the sedimentation rate of cell flocs up to 250 cm/h is obtained when 10 mg/L of iron oxide is embedded into the cell flocs. The sedimentation rate with the embedding of iron oxide shows about 2 times faster than that of without magnetic particles. This strategy had proven effective for the polishing of the pretreated synthetic fertilizer wastewater by removing up to 53%, 74% and 70% of ortho-phosphate, nitrate and ammoniacal nitrogen, respectively. In addition, the presence of iron oxide particles and chitosan in microalgae harvesting that showed no adverse effect toward the quantity and quality of extracted lipid. This strategy is proven feasible for fertilizer wastewater treatment and biodiesel production.

Rapid magnetic modification of diamagnetic particulate and high aspect ratio materials

Novel method for rapid magnetic modification of diamagnetic powder and high aspect ratio materials has been developed. This procedure is based on thorough mixing of diamagnetic materials with suspensions of magnetite nano- and microparticles in highly volatile organic solvents (namely n-pentane or petroleum ether) followed by a drying step. Due to the low boiling point of the solvents used during magnetic modification, the whole process can be performed in a very short time. The prepared magnetically modified materials are stable in water for a long time, without the release of magnetic particles from the modified surface. Magnetic response of the resulting composites allows their simple separation using a permanent magnet. In addition, they have a character of composite nanozymes exhibiting peroxidase-like activity mainly due to the presence of iron oxide particles. The described method is a very efficient alternative to the previously developed magnetic modification procedures.

Biochars and their magnetic derivatives as enzyme-like catalysts mimicking peroxidases

Various materials have been extensively investigated to mimic the structures and functions of natural enzymes. We describe the discovery of a new catalytic property in the group of biochar-based carbonaceous materials, which are usually produced during biowaste thermal processing under specific conditions. The tested biochars exhibited peroxidase-like catalytic activity. Biomaterial feedstock, pyrolysis temperature, size of resulting biochar particles or biochar modification (e.g., magnetic particles deposition) influenced the peroxidase-like activity. Catalytic activity was measured with the chromogenic organic substrates N,N-diethyl-p-phenylenediamine (DPD) or 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of hydrogen peroxide. Magnetic biochar composite was studied as a complementary material, in which the presence of iron oxide particles enhances catalytic activity and enables smart magnetic separation of catalyst even from complex mixtures. The activity of the selected biochar had an optimum at pH 4 and temperature 32 °C; biochar catalyst can be reused ten times without the loss of activity. Using DPD as a substrate, Km values for native wood chip biochar and its magnetic derivative were 220 ± 5 μmol L−1 and 690 ± 80 μmol L−1, respectively, while Vmax values were 10.1 ± 0.3 μmol L−1 min−1 and 16.1 ± 0.4 μmol L−1 min−1, respectively. Biochar catalytic activity enabled the decolorization of crystal violet both in the model solution and the fish pond water containing suspended solids and dissolved organic matter. The observed biochar enzyme mimetic activity can thus find interesting applications in environmental technology for the degradation of selected xenobiotics. In general, this property predestines the low-cost biochar to be a perspective supplement or even substitution of common peroxidases in practical applications.

In vivo assessment of tumour associated macrophages in murine melanoma obtained by low-field relaxometry in the presence of iron oxide particles

Tumour-associated macrophages (TAM) are forced by cancer cells to adopt an anti-inflammatory phenotype and secrete factors to promote tumour invasion thus being responsible for poor patient outcome. The aim of this study is to develop a clinically applicable, non-invasive method to obtain a quantitative TAM detection in tumour tissue. The method is based on longitudinal proton relaxation rate (R1) measurements at low field (0.01–1 MHz) to assess the localization of ferumoxytol (clinical approved iron oxide particles) in TAM present in melanoma tumours, where R1 = 1/T1. R1 at low magnetic fields appears highly dependent on the intra or extra cellular localization of the nanoparticles thus allowing an unambiguous TAM quantification. R1 profiles were acquired on a Fast Field-Cycling relaxometer equipped with a 40 mm wide bore magnet and an 11 mm solenoid detection coil placed around the anatomical region of interest. The R1 values measured 3 h and 24 h after the injection were significantly different. At 24 h R1 exhibited a behavior similar to “in vitro” ferumoxytol-labelled J774A.1 macrophages whereas at 3 h, when the ferumoxytol distribution was extracellular, R1 exhibited higher values similar to that of free ferumoxytol in solution. This finding clearly indicated the intracellular localization of ferumoxytol at 24 h, as confirmed by histological analysis (Pearls and CD68 assays). This information could be hardly achievable from measurements at a single magnetic field and opens new horizons for cell tracking applications using FFC-MRI.

Iron Oxide Nano-Particle Based Photochromic Composite Films

Abstract Iron oxide (α-Fe2O3 and α-FeOOH)-based composite films were fabricated using an FeCl3·6H2O ethanol solution and transparent urethane resin. Iron oxide particles 50–90 nm in diameter were observed in the resulting composite films; analyses by Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy confirmed the presence of iron oxide particles in the films. The films were initially yellowish-brown and turned greenish-gray upon UV irradiation. After UV irradiation of the films, their bandgap decreased (Bürstein–Moss effect). When the composite films (after UV irradiation) were placed in a dark room, their color and bandgap were restored to their initial states. Thus, the iron oxide-based composite films exhibited reversible photochromism.

K- and Ca-promoted ferrosilicates for the gas-phase epoxidation of propylene with O2

In the propylene epoxidation reaction with Fe-SiO2 catalysts the presence of iron oxide particles has a detrimental effect due to the total combustion of propylene on these iron species. Thus, the complete elimination of the iron oxide particles is presented as a preliminary strategy in order to increase the selectivity towards propylene oxide in iron-based catalysts. In this sense, a simple post-treatment of the catalysts with alkali or alkaline-earth elements (such as K or Ca, respectively) has proven effective in the total elimination of these iron oxide particles. Furthermore, the addition of K and Ca has modified the physico-chemical properties of the catalysts, decreasing their superficial acidity and (for higher K or Ca loadings) masking/blocking the active sites responsible for the catalytic reaction. With all this, it is shown that K has a higher efficiency removing the iron oxide particles compared with Ca (for the same molar ratios) and that a higher amount of K (compared to Fe) is required for the complete elimination of the iron oxide particles. A considerable propylene oxide selectivity enhancement (up to 65%) has been obtained for the K-promoted Fe0.005SiO2 and Fe0.01SiO2 catalysts using O2 as sole oxidant.

A Thorough Study: In-Situ Aluminium LM6 Metal Matrix Composites Reinforced with Iron Oxide and MWCNTs

This paper aims on synthesis and characterization of Aluminium LM6 composites, discontinuously reinforced with iron oxide (γ-Fe2O3) particles and MWCNTs under different compositions using stir casting method. An investigation of carried out to determine physical, mechanical and electromagnetic properties of LM6 composites. Alumina particles were produced in-situ by reaction with iron oxide reduced by aluminium. Morphological studies were carried out to reveal the surface morphology and chemical composition of the prepared sample. EMI shielding effectiveness was measured using transmission line waveguide technique in the X-band. Observations yield that the presence of iron oxide particles and MWCNTs in Aluminium matrix affects EMI shielding property of the composite in X-band (8-12 GHz) frequency range. The reflection and absorption coefficients have shown reflection dominated electromagnetic energy attenuation of the composite samples, which was tailored by incorporation ofiron oxide and MWCNTs. Simultaneous Thermal Analysis (STA) technique was performed for uniform ramp and purging rates to analyse the thermal stabilities of composites. The hardness, impact strength and wear rate of both composites increases while the compression strength was compromised. Furthermore, incorporating MWCNT along with iron oxide had reducing effect on the density of composite. The effect of dispersants on the distribution of reinforcements and the controlled distribution of MWCNT is further to more research and discussion.

Formation of the ZnFe2O4 phase in an electric arc furnace off-gas treatment system

To better understand the phenomena of ZnFe2O4 spinel formation in electric arc furnace dust, the dust was characterized with particle size analysis, X-ray fluorescence (XRF), electron backscatter diffraction (EBSD), and electron probe micro-analysis (EPMA). Different ZnFe2O4 formation reaction extents were observed for iron oxide particles with different particle sizes. ZnO particles were present as both individual particles and aggregated on the surface of larger particles. Also, the slag particles found in the off-gas were shown not to react with the zinc vapor.After confirming the presence of a ZnFe2O4 formation reaction, the thermodynamic feasibility of in-process separation – a new electric arc furnace dust treatment technology – was reevaluated. The large air intake and the presence of iron oxide particles in the off-gas were included into the thermodynamic calculations. The formation of the stable ZnFe2O4 spinel phase was shown to be thermodynamically favorable in current electric arc furnace off-gas ducts conditions even before reaching the post combustion chamber.

Coating Effects of Nano-Sized Particles onto Sand Surfaces: Small Strain Stiffness and Contact Mode of Iron Oxide–Coated Sands

AbstractThe presence of nano-sized particles on the surface of sand grains can significantly influence the mechanical, physical, and chemical behavior of the sand because of the effects of contacts between particles. This study quantified the change in small strain stiffness caused by the presence of iron oxide particles (hematite and goethite) that were chemically sorbed onto uncemented silica sand. Particularly, the change in contact mode between sand particles, caused by the presence of the nanoparticles, was studied. The iron oxide coating density of coated sands was controlled by changing the substrate sand particle size, ranging from 0.11 to 0.72 mm in diameter, with corresponding iron contents ranging from 0.13 mg iron oxide/g sand (goethite) to 6.4 mg iron oxide/g sand (hematite). The presence of the iron oxide nanoparticles altered the contact mode between particles and, correspondingly, the small strain stiffness as a function of the initial relative density, applied stress, iron content, and su...

Investigation ofFe2O3/SiO2Nanocomposite by FESEM and TEM

Superparamagnetic maghemite nanoparticles were synthesized using Massart’s procedure. Nanocomposites that consist of the synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica xerogel prepared by sol-gel technique. The system was then heated for 3 days at 140°C. The structure, morphology, and texture of the system were analysed by FESEM and TEM. The result from FESEM showed that the silica gel forms a network structure, which contained numerous pores, with an average pore size of 15 nm. EDX line profile analysis was carried out, and the result indicated that the embedded particles were iron oxide. EELS showed the presence of Fe-L2signal, which confirmed the presence of iron oxide particles within the silica matrix. The average diameters were 5.0 nm for as-synthesized maghemite nanoparticles and 4.4 nm for the embedded maghemite nanoparticles in silica xerogel matrix. The embedded maghemite nanoparticles in nanocomposite also showed a narrower distribution compared to as-synthesized particles. The magnetization values at 10 kOe applied field,Ms10 kOe, were 9.53 emu/g and 1.79 emu/g for as-synthesized and embedded nanoparticles, respectively. A reduction in average crystallite size was observed for the dispersed maghemite particles after formation of the nanocomposite indicating a slight dissolution of maghemite nanoparticles in silica gel.

Use of EIS to Measure the Rate of H2O2 Decomposition on a Bulk Magnetite Electrode in Alkaline Solution

The new generation of supercritical cooled water reactors (SCWR) are susceptible to particulate fouling as a result of corrosion product sedimentation. Iron oxides are a major component of corrosion products and are also known to catalyze hydrogen peroxide decomposition. This work aimed to investigate the rate of H2O2 decomposition on the surface of a magnetite bulk electrode by using electrochemical impedance spectroscopy. A magnetite bulk electrode was immersed in a suspension of various concentrations of magnetite particles and initial H2O2 concentration of 10−2 M. It was observed that the electrochemical response of the magnetite surface (which is partially oxidized to γ − Fe+3 species) is a function of H2O2 concentration. Therefore, at different time intervals EIS was used to obtain charge transfer resistance as a proxy variable for hydrogen peroxide concentration. These measurements were compared to results obtained by permanganate titration. It was observed that the changes of decomposition current density extracted from the EIS data fitting process for various conditions were in good agreement with the titration results. H2O2 decomposition in the presence of iron oxide particles was found to be a second-order reaction with rate constants of 0.015 and 0.017 min−1g−1L (obtained from EIS and titration methods, respectively).

Homo- and Heterogeneous Mercury Oxidation in a Bench-Scale Flame-Based Flow Reactor

An experimental study of hetero- and homogeneous mercury oxidation chemistry was conducted in a bench-scale flame-based flow reactor with a residence time of 2.9 s. Homogeneous mercury oxidation levels increased with an increasing HCl concentration, with oxidation increasing to 29% at HCl concentrations of 555 parts per million by volume (ppmv). The presence of SO2 alone also led to Hg oxidation, with approximately 20% oxidation observed at SO2 concentrations ranging from 100 to 900 ppmv. When both HCl and SO2 were present, mercury oxidation was enhanced in the presence of SO2 when the concentration of HCl was 200 ppmv and inhibited when concentration of HCl was 555 ppmv. To examine heterogeneous effects, iron oxide or montmorillonite particles were injected into the post-flame gases of the system. Mercury oxidation by HCl was enhanced at high iron oxide particle concentrations (>100 mα-Fe2O32/m3 of flue gas) compared to the homogeneous system. When iron oxide particles were injected in the presence of 100–400 ppmv SO2 without HCl, mercury oxidation was enhanced at particle loadings less than or equal to 1 mα-Fe2O32/m3 of flue gas and decreased with an increasing particle loading. At a SO2 concentration of 500 ppmv, mercury oxidation increased with an increasing particle concentration. Without HCl or SO2 in the system, mercury oxidation in the presence of iron oxide particles alone was found to be negligible. To determine if the increased oxidation by HCl or SO2 occurred solely because of an increased surface area, montmorillonite particles were injected, and under these conditions, no increase in the extent of mercury oxidation was observed, suggesting that iron oxide particle surfaces are an important contributor to the promotion of mercury oxidation in coal combustion systems.

The Sulfur Dioxide Removal and Regeneration Properties of MgO-Based Sorbents Promoted with Ceria and Iron Oxide

Nano-size MgO-based sorbents that were promoted with ceria and iron oxide were prepared using the coprecipitation method. The sulfur removing capacity and the role of ceria and iron oxide promoters were investigated using a fixed-bed reactor and X-ray diffraction (XRD). The ceria played an important role in the catalytic oxidation of SO 2 to SO 3 which could be easily absorbed by the MgO. In order for sulfate absorption to occur, SO 2 must be oxidized to SO 3 before absorption to a pure MgO. The iron oxide exhibited a lowering of the regeneration temperature of the sulfated sorbent under a residue fluid catalytic cracking (RFCC) condition. These results can be explained by the presence of iron oxide particles that interact strongly with MgO support. The MgO-based sorbent that was promoted with ceria and iron oxide showed excellent characteristics in that it could satisfy a large amount of SO 2 absorption and fast regeneration.

In vivo intermolecular zero-quantum coherence MR spectroscopy in the rat spinal cord at 17.6 T: a feasibility study

The feasibility of in vivo magnetic resonance spectroscopy of the healthy rat spinal cord at 17.6 T using conventional methods and intermolecular zero-quantum coherence (iZQC) spectroscopy is explored and the performance of both approaches is compared. Localised spectra were acquired at 17.6 T from three healthy Fisher rats and phantoms with injected iron-oxide particles using the PRESS and a modified HOMOGENIZED sequence. Well-resolved in vivo spectra showing the four singlet resonances of creatine, choline, and N-acetyl aspartate were obtained with both approaches. iZQC spectra were acquired from larger voxels, but did not provide higher sensitivity or resolution in the healthy spinal cord. In the presence of paramagnetic iron-oxide particles, the quality of in vitro spectra acquired with PRESS declined and was strongly dependent on the quality of the local shim. iZQC spectra were not affected by the presence of iron-oxide particles and provided narrow lines (9 Hz) independent of the shim. In vivo iZQC spectroscopy of the rat spinal cord is possible. The robustness in presence of local field distortions makes iZQC methods a promising alternative for the investigation of tissue containing labelled cells, implants, or clotted blood. New application of MRS to tissue inaccessible using conventional methods may thus become possible.

Encapsulation of magnetic particles via miniemulsion polymerization of styrene. II. Effect of some parameters on the polymerization of styrene

AbstractEffects of some parameters on the polymerization of Styrene (St) during encapsulation of iron oxide particles via miniemulsion polymerization have been investigated. At the early stage of reaction, polymerization rate increased slightly with the increase of sonicating time, and then it leveled off. The polymerization rate increased with the increase of KPS at the early stage of polymerization, which tendency is analogous to the result of polymerization of St in miniemulsion without the presence of iron oxide particles. The increase of iron oxide not only decreased the polymerization rate but also resulted in poorer monodisperse of the particles when keeping the amount of dispersant constant. The dispersant played an important role in the encapsulation of magnetic particles via miniemulsion polymerization of St. It not only made the iron oxide disperse well in monomer droplets but also led to a much faster polymerization than that of no dispersant in system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Phosphorus retention in calcareous soils and the effect of organic matter on its mobility.

A survey of the interactions between phosphorus (P) species and the components of calcareous soils shows that both surface reactions and precipitation take place, especially in the presence of calcite and limestone. The principal products of these reactions are dicalcium phosphate and octacalcium phosphate, which may interconvert after formation. The role of calcium carbonate in P retention by calcareous soils is, however, significant only at relatively high P concentrations – non-carbonate clays play a more important part at lower concentrations. In the presence of iron oxide particles, occlusion of P frequently occurs in these bodies, especially with forms of the element that are pedogenic in origin. Progressive mineralization and immobilization, often biological in nature, are generally observed when P is added as a fertilizer.Manure serves both as a source of subsurface P and an effective mobilizing agent. Blockage of P sorption sites by organic acids, as well as complexation of exchangeable Al and Fe in the soil, are potential causes of this mobilization. Swine and chicken manure are especially rich P sources, largely due the practice of adding the element to the feed of nonruminants. Humic materials, both native and added, appear to increase recovery of Olsen P. In the presence of metal cations, strong complexes between inorganic P and humates are formed. The influence of humic soil amendments on P mobility warrants further investigation.

Comparative study of Cu-ZSM-5 and Fe-ZSM-5 in the SCR of NOx with i-C4H10

Catalytic activity tests were carried out on Cu-ZSM-5 and Fe-ZSM-5 catalysts for the reduction of NOx with i-C4H10. Formation of CO was the major drawback of Fe-ZSM-5 catalyst, which was attributed to the presence of iron oxide particles. Increasing the Si/Al ratio appeared to slightly strengthen Cu-ZSM-5 catalyst in the presence of water vapor.

Impact of natural nanophases on heavy-metal retention in zeolite-supported reactive filtration facilities for urban run-off treatment.

The retention of lead in zeolite-supported sand-filter columns has been tested with focus on the effect of potentially mobile natural nanophases (natural colloids, humic substances). It could be shown that interaction of lead with natural nanophases enhanced the mobility of the contaminant. In the presence of iron oxide particles (goethite) a normal breakthrough of lead was observed. Humic substance can act as a carrier for lead itself and can enhance the mobility of lead bound to inorganic nanophases, because of the increased mobility of the nanophases in the presence of humic substances.