Production and Characterization of Green Biosorbent Based on Modified Corn Cob Decorated Magnetite Nanoparticles

In most developing countries, particularly in the countries of sub-Saharan Africa, corn cobs are considered as waste polluting the environment during the harvest period of this cereal. In order to valorize this agricultural waste, high-performance, inexpensive and low-energy consumption magnetic bioadsorbents were prepared from corn cobs. The chemically activated raw corn cob was magnetized by coating the surface with magnetite nanoparticles. The prepared biosorbents were characterized by FT-IR, XRD, FE-SEM associated with EDX, HR-TEM, TG analysis, BET surface area analysis and XPS. The maximum specific surface area of 35.22 m2/g was reached. An attempt to use of these magnetic biosorbents for the removal of heavy metal like Cr(VI) from aqueous solution was envisaged.

Application of Modified Silica Coated Magnetite Nanoparticles for Removal of Iodine from Water Samples

The adsorption of iodine onto silica coated magnetite nanoparticles(im-SCMNPs) that modified with imidazole was investigated for removal of high concentrations of iodine from wastewater. Modified silica magnetite nanoparticles showed high efficiency in removing iodine from wastewater samples. The optimum pH for iodine removal was 7.0-8.0. The adsorption capacity was evaluated using both the Langmuir and Freundlich adsorption isotherm models. The size of the produced magnetite nanoparticles was determined by X-ray diffraction analysis and scanning electron microscopy. Synthesized magnetite nanoparticles showed the high adsorption capacity and would be a good method to increase adsorption efficiency for the removal of iodine in a wastewater treatment process. The Langmuir adsorption capacity(qmax) was found to be 140.84 mg/g of the adsorbent.

Interactions of ferro-nanoparticles(hematite and magnetite) with reservoir sandstone: implications for surface adsorption and interfacial tension reduction

There are a few studies on the use of ferro-nanofluids for enhanced oil recovery,despite their magnetic properties;hence,it is needed to study the adsorption of iron oxide(Fe2 O3 and Fe3 O4) nanoparticles(NPs) on rock surfaces.This is important as the colloidal transport of NPs through the reservoir is subject to particle adsorption on the rock surface.Molecular dynamics simulation was used to determine the interfacial energy(strength) and adsorption of Fe2 O3 and Fe3 O4 nanofluids infused in reservoir sandstones.Fourier transform infrared spectroscopy and X-ray photon spectroscopy(XPS) were used to monitor interaction of silicate species with Fe2 O3 and Fe3 O4.The spectral changes show the variation of dominating silicate anions in the solution.Also,the XPS peaks for Si,C and Fe at 190,285 and 700 eV,respectively,are less distinct in the spectra of sandstone aged in the Fe3 O4 nanofluid,suggesting the intense adsorption of the Fe3 O4 with the crude oil.The measured IFT for brine/oil,Fe2 O3/oil and Fe3 O4/oil are 40,36.17 and 31 mN/m,respectively.Fe3 O4 infused with reservoir sandstone exhibits a higher silicate sorption capacity than Fe2 O3,due to their larger number of active surface sites and saturation magnetization,which accounts for the effectiveness of Fe3 O4 in reducing IFT.

Highly efficient [C8mim][Cl] ionic liquid accompanied with magnetite nanoparticles and different salts for interfacial tension reduction

The 1-octyl-3-methylimidazolium chloride, [C8 mim][Cl] ionic liquid(IL) was used as a novel surfactant in n-heptane/water system. The interfacial tensions(IFT) were measured and corresponding variations were investigated. An IFT reduction of 80.8% was appropriate under the IL CMC of about 0.1 mol·L^-1 and stronger effects were achieved when magnetite nanoparticles and salts were present profoundly under alkaline p Hs.The equilibrium IFT data were accurately simulated with the Frumkin adsorption model. Hereafter, the saturated surface concentration, equilibrium constant and interaction parameter were obtained and their variations were demonstrated. Further, emulsion stability and contact angle of oil/water interface over quartz surface were studied. The oil/water emulsion stability was hardly changed with nanoparticles;however, the stability of oil/water + IL emulsions was significantly improved. It was also revealed that the presence of sodium and calcium chloride electrolytes fortifies the IL impact, whereas sodium sulfate weakens. From dynamic IFT data and fitting with kinetic models, it was found that the IL migration toward interface follows the mixed diffusion–kinetic control model. Consequently, the IL diffusion coefficient and the appropriate activation energy were determined.

Green Synthesis of Magnetite Nanoparticles Using Aqueous Leaves Extracts of <i>Azadirachta indica</i>and Its Application for the Removal of As(V) from Water

Because of various disadvantages of chemical synthesis processes, these days people are attracting towards green synthesis processes as it is devoid of toxic by-products, cost-effective and eco-friendly. In this study, a simple green synthesis method is applied for the synthesis of magnetite (Fe3O4) nanoparticles (MNPs) by co-precipitation of FeCl3·6H2O and FeSO4·7H2O in the molar ratio of 2:1 using Azadirachta indica leaves extract under nitrogen environment. FTIR, XRD, SEM etc. were used to characterize the synthesized MNPs. Batch adsorption experiments were carried out to determine adsorption equilibrium of As(V) as a function of pH, adsorbent dose, contact time and different initial concentrations. Kinetics results were best described by pseudo-second order model with rate constant value 0.0052 g/(mg·min). The equilibrium adsorption isotherm was best fitted with Langmuir adsorption isotherm model. The maximum adsorption capacity was found to be 62.89 mg/g at pH 2. MNPs showed a high affinity for As(V) and avoids filtration for solid-liquid separation, thus it would be employed as a promising material for the removal of As(V) from water.

Comparative Study between Magnetite Nanoparticles and Magnetite/Silver as a Core/Shell Nanostructure

Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe2+ and Fe3+. In case of M/Ag NPs, MNPs (core) were separately coated by silver metal (shell) in presence of glucose as a reducing agent. The particle size and morphology of the nanoparticles were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Magnetic properties were investigated by vibrating sample magnetometry (VSM). The superparamagnetic natures of the nanoparticles were confirmed by the absence of the hysteresis loop. Coverage with silver produced a core-shell heterostructure which weakens magnetization of MNPs, inducing an inert character to the fnal nanostructure. The surface conjugation of MNPs with silver metal has been employed in order to improve the compatibility of magnetite nanoparticles to overcome their limitations in practical applications.

Conjugation of Magnetite Nanoparticles with Melanogenesis Substrate, NPrCAP Provides Melanoma Targeted, <i>in Situ</i>Peptide Vaccine Immunotherapy through HSP Production by Chemo-Thermotherapy

In order to develop melanoma-targeted in situ peptide vaccine immunotherapy, magnetite nanoparticles were conjugated with a melanogenesis substrate, N-propionyl cysteaminylphenol (NPrCAP). Magnetite nanoparticles introduced thermotherapy which caused non-apoptotic cell death and generation of heat shock protein (HSP) upon exposure to alternating magnetic field (AMF). NPrCAP was expected to develop a melanoma-targeted therapeutic drug because of its selective incorporation into melanoma cells and production of highly reactive free radicals, that result in not only oxidative stress but also apoptotic cell death by reacting with tyrosinase.

Review: Low Cost, Environmentally Friendly Humic Acid Coated Magnetite Nanoparticles (HA-MNP) and Its Application for the Remediation of Phosphate from Aqueous Media

Phosphate is a primary nutrient required for the normal functioning of many organisms in the ecosystem. However, presence of excess phosphate into the aquatic systems leads to eutrophication which can promote harmful algal growth and decrease the amount of dissolved oxygen in water. Municipal, industrial and agricultural run-off wastewaters are the major point sources for phosphate discharges. There are different methods to remove phosphates from water. Among these, adsorption is the most widely accepted method for phosphate removal because of its high efficiency, minimum cost, easy and simple operation and applicability at lower concentrations. The emphasis of this review, is to consolidate low cost, environmentally friendly humic acid coated magnetite nanoparticles (HA-MNP) and its application for the remediation of phosphate from aqueous media. The magnetic nanoparticles could be easily separated from the reaction mixture by using a simple hand held magnet and adsorption studies demonstrate the fast and effective separation of phosphate with maximum removal efficiency > 90% at pH 6.6. The adsorption behavior follows the Freundlich isotherm and the removal of phosphate is found higher at acidic and neutral pH compared to basic conditions. The nanoparticles exhibit good selectivity and adsorption efficiency for phosphate in the presence of co-existing ions such as Cl-, ?and??with some inhibition effect by??and finally, the effect of temperature on the adsorption reveals that the process is endothermic and spontaneous.

Properties of Biogenic Magnetite Nanoparticles in the Radula of Chiton Acanthochiton rubrolineatus Lischke

The properties of biogenic magnetite（Fe 3 O 4 ）nanoparticles in chiton acanthochiton rubrolineatus lischke were characterized by selected electron diffractometry,high resolution transmission electron microscopy,Fourier transform infrared spectroscopy,M·ssbauer spectroscopy and magnetization measurements.Results showed that the magnetite nanoparticles presented crystalline appearance,exhibiting strong absorptions at 595,1 463,3 467 cm-1 and weak adsorptions at 1 697,1 113,1 048,848,445 cm-1 in FT-IR,two partially overlapping sextets in M·ssbauer spectrum,and the area ratio of the sextets was 1.08.Also,the particles exhibited ferromagnetic behavior,and had 82 A·m2/kg saturation magnetization,1.4·104 A/m coercive force and 4.0 A·m2/kg remnant magnetization,respectively.The investigation indicates that the biogenic magnetite nanoparticles mineralized in the chiton are impure in composition and non-stoichiometric.

Analysis of Spectroscopic, Optical and Magnetic Behaviour of PVDF/PMMA Blend Embedded by Magnetite (Fe₃O₄) Nanoparticles

In the present work, magnetite (Fe3O4) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluoride (PVDF) and (methyl methacrylate) (PMMA) doped with different concentrations of Fe3O4 nanoparticles have been prepared. The structural, optical, and magnetization properties of the nanocomposite samples were studied using suitable techniques. The X-ray study reflected that the cubic spinal structure of pure Fe3O4 crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe3O4 within PVDF/PMMA matrices. The FT-IR analysis demonstrated the miscibility between the PVDF and PMMA blend with the interaction between the polymer blend and Fe3O4. The values of the band gap from UV-Vis study were decreased up to 4.21 eV, 3.01 eV for direct and indirect measurements, respectively. The magnetization was measured as a function of the applied magnetic field in the range of −2000 - 2000 Oersted. The curves of the magnetization indicated a paramagnetic behavior of pure Fe3O4 nanoparticles and PVDF/PMMA-Fe3O4 nanocomposites. The values of saturation magnetization for pure Fe3O4 are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe3O4 content.

Magnetite nanoparticles coat around activated -alumina spheres: A case of novel protection of moisture-sensitive materials against hydration

Protection of various materials against hydration is of continuing interest to chemists and material scientists. We report on stabilization of porous surface of activated -alumina spheres (AAS) against hydration by an adhesive coat of nano-magnetite particles. The nano-Fe3O4-coated AAS were prepared in the ultrasound-agitated suspension of magnetite nanoparticles in heptane and were characterized by using X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area analysis and X-ray photoelectron spectroscopy (XPS). It is deduced that nanoparticle-alumina bonding interaction in non-polar organic solvent is enhanced by van der Waals attractive forces and that sonication induces changes in alumina morphology only in regions of contact between alumina and magnetite nanoparticles. The coated AAS submerged in still water avoid hydration and remain permeable by small gaseous (N2) molecules, while those soaked in moving water lose part of their coat and undergo hydration. The pristine and the coated AAS were briefly compared for their ability to degrade model antibiotics by using LC-MS analysis. It is confirmed that the degradation of trimethoprim is more efficient on the coated AAS. Our results are challenging for further research of Coulombic interactions between nano-particles and appropriate solid supports.

Hydrothermal Liquefaction of Water Hyacinth: Effect of Process Conditions and Magnetite Nanoparticles on Biocrude Yield and Composition

In this work, an efficient way of converting the water hyacinth to biocrude oil using magnetite nanoparticles (MNPs) as potential catalysts was demonstrated for the first time. MNPs were synthesised by co-precipitation and used in the hydrothermal liquefaction (HTL) of water hyacinth at different reaction conditions (temperature, reaction time, MNPs to biomass ratio and biomass to water ratio). The best reaction conditions were as follows: temperature— 320, reaction time—60 minutes, MNPs to biomass ratio – 0.2 g/g and biomass to water ratio – 0.06 g/g. HTL in presence of MNPs gave higher biocrude yields compared to HTL in absence of MNPs. The highest biocrude yield was 58.3 wt% compared to 52.3 wt% in absence of MNPs at similar reaction conditions. The composition of biocrude oil was analysed using GC-MS and elemental analysis. GC-MS results revealed that HTL in presence of MNPs led to an increase in the percentage area corresponding to hydrocarbons and a reduction in the percentage area corresponding to oxygenated compounds, nitrogenated compounds and sulphur compounds. Elemental analysis revealed an increase in the hydrogen and carbon content and a reduction in the nitrogen, oxygen and sulphur content of the biocrude when HTL was done in presence of MNPs compared to HTL in absence of MNPs. The nanoparticles were recovered from the biochar by sonication and magnetic separation and recycled. The recycled MNPs were still efficient as HTL catalysts and were recycled five times. The application of MNPs in the HTL of water hyacinth increases the yield of biocrude oil, improves the quality of biocrude through removal of hetero atoms, oxygen and sulphur compounds and is a potentially economical alternative to the traditional petroleum catalysts since MNPs are cheaper, widely available and can be easily recovered magnetically and recycled. This will potentially lead to an economical, environmentally friendly and sustainable way of producing biofuels from biomass.

四氧化三铁纳米颗粒的制备与应用

纳米材料是一种具有重要应用前景的新型材料,由于其独特的物理和化学性质,纳米材料的研究和应用领域正在不断扩大和深化。四氧化三铁(Fe_(3)O_(4))纳米颗粒由于其特殊的磁性、电学性质与极佳的生物相容性,使其在医学领域具有广泛的应用前景。系统介绍了Fe_(3)O_(4)纳米颗粒化学液相的制备方法和近年来在医学领域的实际应用。

Inductive heat property of Fe_3O_4 nanoparticles in AC magnetic field for local hyperthermia

Magnetite (Fe3O4) nanoparticles with different magnetic properties were prepared by coprecipitation of Fe3+ and Fe2+ with aqueous NaOH solution. The inductive heat properties of Fe3O4 nanoparticles in an alternating current (AC) magnetic field were investigated for local hyperthermia. The maximum saturation magnetization Ms of Fe3O4 nanoparticles is 65.53 emu·g-1 under the optimum conditions of Fe3+: Fe2+ molar ratio at 1.8:1. The Ms of Fe3O4 nanoparticles decreased as the Fe3+/Fe2+ molar ratio increased. But the coercivity Hc increases with the increasing of Fe3+/Fe2+ molar ratio. Exposed in the AC magnetic field for 29 min, the temperatures of physiological saline suspension containing Fe3O4 nanoparticles were 42-97.5 ℃. The inductive heat property of Fe3O4 nanoparticles in AC magnetic field decreases as Hc increases, but increases with the increasing of Ms. The Fe3O4 nanoparticles would be useful as good thermoseeds for localized hyperthermia treatment of cancers.

Surface modification of Fe_3O_4 nanoparticles and their magnetic properties

Fe3O4 magnetic nanoparticles were synthesized by the hydrothermal method, and the influences of the surfactant sodium bis（2-ethylhexyl） sulfosuecinate （AOT） on the particles were investigated. The structure, morphology, and magnetic properties of the products were characterized by X-ray powder diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FT-IR）, and vibrating sample magnetometer （VSM）. It is confirmed that the as-prepared nanoparticles have been modified by using the surfactant during the synthesis process. The amount of the surfactant has an effect on the size, the dispersal, and the magnetic properties of the particles. Besides, the mechanisms of the influences were also discussed.

Synthesis and Characterization of Superparamagnetic Fe₃O₄@SiO₂Core-Shell Composite Nanoparticles

The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investi-gated. The results revealed that the Fe3O4@SiO2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe3O4@SiO2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.

Synthesis and characterization of Fe_3O_4@SiO_2 magnetic composite nanoparticles by a one-pot process

Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder（34.85 A·m^2·kg^–1） was markedly lower than that of the Fe3O4 powder（79.55 A·m^2·kg^–1）, which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.