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 agricu...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 m<sup>2</sup>/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.展开更多
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 nano...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.展开更多
We described a simple one-step process for the synthesis of oleic acid-capped magnetite nanoparticles using the dimethyl sulfoxide(DMSO) to oxidize the precursor Fe^(2+) at 140℃.By adjusting the alkalinity of the rea...We described a simple one-step process for the synthesis of oleic acid-capped magnetite nanoparticles using the dimethyl sulfoxide(DMSO) to oxidize the precursor Fe^(2+) at 140℃.By adjusting the alkalinity of the reaction system,magnetite nanoparticles with two sizes of 4 and 7 nm could be easily achieved.And the magnetite nanoparticles coated by oleate were well-monodispersed in organic solvent.展开更多
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...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.展开更多
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 investiga...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.展开更多
<span style="font-family:Verdana;">Because of various disadvantages of chemical synthesis processes, these</span><span> </span><span style="font-family:Verdana;">days ...<span style="font-family:Verdana;">Because of various disadvantages of chemical synthesis processes, these</span><span> </span><span style="font-family:Verdana;">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 (Fe</span><sub><span style="vertical-align:sub;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">O</span><sub><span style="vertical-align:sub;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">) nanoparticles (MNPs) by co-precipitation of FeCl</span><sub><span style="vertical-align:sub;font-family:Verdana;">3·</span></sub><span style="font-family:Verdana;">6H</span><sub><span style="vertical-align:sub;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O and FeSO</span><sub><span style="vertical-align:sub;font-family:Verdana;">4·</span></sub><span style="font-family:Verdana;">7H</span><sub><span style="vertical-align:sub;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O in the molar ratio of 2:1 using </span><span><i></i></span><i><span style="font-family:Verdana;">Azadirachta indica</span><span></span></i><span style="font-family:Verdana;"> 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 describe</span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;"> 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 </span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">high affinity for As(V) and avoids filtration for solid-liquid separation, thus it would be employed as a promising material </span><span style="font-family:Verdana;">for </span><span style="font-family:Verdana;">the removal of As(V) from water.</span>展开更多
Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe<sup>2+</sup> and Fe<sup>3+</sup>. In case of M/Ag NPs, MNPs (cor...Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe<sup>2+</sup> and Fe<sup>3+</sup>. 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.展开更多
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 intr...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.展开更多
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 ...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.展开更多
Different methods have been investigated for the synthesis of magnetic nanoparticles. Control of the particle size, dispersion, purity and stability have been always regarded an issue. In this study magnetite (Fe304...Different methods have been investigated for the synthesis of magnetic nanoparticles. Control of the particle size, dispersion, purity and stability have been always regarded an issue. In this study magnetite (Fe304) superparamagnetic nanoparticles with a size range about 20 nm have been successfully synthesized using chemical co-precipitation method from the solution of ferrous/ferric mixed salt-solution in alkaline media in oxygen-free environment. The sol-gel method has been chose to encapsulate magnetic nanoparticles into silica matrix. The phase structures, morphologies, surface area, functional classes and magnetic properties have been characterized by X-ray diffraction, SEM and AFM, BET, FT-IR and VSM. The results showed that the resultant films, consisting of encapsulated magnetite have crack free and smooth surface with a roughness value 1.5 rim.展开更多
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,Four...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.展开更多
In the present work, magnetite (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluo...In the present work, magnetite (Fe<sub>3</sub>O<sub>4</sub>) 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 Fe<sub>3</sub>O<sub>4</sub> 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 Fe<sub>3</sub>O<sub>4</sub> crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe<sub>3</sub>O<sub>4</sub> 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 Fe<sub>3</sub>O<sub>4</sub>. 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 Fe<sub>3</sub>O<sub>4</sub> nanoparticles and PVDF/PMMA-Fe<sub>3</sub>O<sub>4</sub> nanocomposites. The values of saturation magnetization for pure Fe<sub>3</sub>O<sub>4</sub> are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe<sub>3</sub>O<sub>4</sub> content.展开更多
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...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.展开更多
In this work, an efficient way of converting the water hyacinth <span style="font-family:Verdana;">to</span><span style="font-family:;" "=""><span style="fo...In this work, an efficient way of converting the water hyacinth <span style="font-family:Verdana;">to</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> biocrude oil usi</span><span style="font-family:Verdana;">ng magnetite nanoparticles (MNPs) as potential catalysts was demo</span><span style="font-family:Verdana;">nstrated 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</span></span><span style="font-family:Verdana;">—</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">320</span><span style="font-family:Verdana;"><img src="Edit_b832a078-c9f1-4a9c-871e-2ed1f0c6e7ac.png" alt="" /></span><span style="font-family:Verdana;">, reaction time</span><span style="font-family:Verdana;">—</span><span style="font-family:;" "=""><span style="font-family:Verdana;">60 minutes, MNPs to biomass ratio – 0.2 g/g and bioma</span><span style="font-family:Verdana;">ss to water ratio – 0.06 g/g. HTL in presence of MNPs gave high</span><span style="font-family:Verdana;">er 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</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">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.</span>展开更多
Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems ...Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems that must be resolved.To this end,a drug carrier incorporating natural magnetic cores in a zeolite framework was developed and applied to the loading of curcumin in ethanol solutions.In this system,curcumin is encapsulated in a zeolite Na(ZNA)magnetic core–shell structure(Fe@Si/ZNA),which can be easily synthesized using an in situ method.Synthesis of Fe_(3)O_(4) nanoparticles was carried out from natural materials using a co-precipitation method.Analysis of the prepared magnetic core–shell structures and composites was carried out using vibrating-sample magnetometery,Fourier transform infrared spectroscopy,transmission electron microscopy,and x-ray diffraction.The cumulative loading of curcumin in the ZNA composite with 9%nanoparticles was found to reach 90.70%with a relatively long half-life of 32.49 min.Stability tests of curcumin loading in the composite showed that adding magnetic particles to the zeolite framework also increased the stability of the composite structure.Adsorption kinetics and isotherm studies also found that the system follows the pseudo-second-order and Langmuir isotherm models.展开更多
文摘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 m<sup>2</sup>/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.
文摘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.
基金supported by the National Natural Science Foundation of China(No.30870679 and 30970787)National Basic Research Program of China(No.2006CB933206 and 2006CB705606)
文摘We described a simple one-step process for the synthesis of oleic acid-capped magnetite nanoparticles using the dimethyl sulfoxide(DMSO) to oxidize the precursor Fe^(2+) at 140℃.By adjusting the alkalinity of the reaction system,magnetite nanoparticles with two sizes of 4 and 7 nm could be easily achieved.And the magnetite nanoparticles coated by oleate were well-monodispersed in organic solvent.
文摘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.
基金financial support by the Bu-Ali Sina University to carry out this research.
文摘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.
文摘<span style="font-family:Verdana;">Because of various disadvantages of chemical synthesis processes, these</span><span> </span><span style="font-family:Verdana;">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 (Fe</span><sub><span style="vertical-align:sub;font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">O</span><sub><span style="vertical-align:sub;font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">) nanoparticles (MNPs) by co-precipitation of FeCl</span><sub><span style="vertical-align:sub;font-family:Verdana;">3·</span></sub><span style="font-family:Verdana;">6H</span><sub><span style="vertical-align:sub;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O and FeSO</span><sub><span style="vertical-align:sub;font-family:Verdana;">4·</span></sub><span style="font-family:Verdana;">7H</span><sub><span style="vertical-align:sub;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O in the molar ratio of 2:1 using </span><span><i></i></span><i><span style="font-family:Verdana;">Azadirachta indica</span><span></span></i><span style="font-family:Verdana;"> 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 describe</span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;"> 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 </span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">high affinity for As(V) and avoids filtration for solid-liquid separation, thus it would be employed as a promising material </span><span style="font-family:Verdana;">for </span><span style="font-family:Verdana;">the removal of As(V) from water.</span>
文摘Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe<sup>2+</sup> and Fe<sup>3+</sup>. 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.
文摘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.
文摘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.
文摘Different methods have been investigated for the synthesis of magnetic nanoparticles. Control of the particle size, dispersion, purity and stability have been always regarded an issue. In this study magnetite (Fe304) superparamagnetic nanoparticles with a size range about 20 nm have been successfully synthesized using chemical co-precipitation method from the solution of ferrous/ferric mixed salt-solution in alkaline media in oxygen-free environment. The sol-gel method has been chose to encapsulate magnetic nanoparticles into silica matrix. The phase structures, morphologies, surface area, functional classes and magnetic properties have been characterized by X-ray diffraction, SEM and AFM, BET, FT-IR and VSM. The results showed that the resultant films, consisting of encapsulated magnetite have crack free and smooth surface with a roughness value 1.5 rim.
基金Funded by the National Natural Science Foundation of China(No.30770582)Doctoral Fund of Commonly Ministry of Education of China(No.20070423013)
文摘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.
文摘In the present work, magnetite (Fe<sub>3</sub>O<sub>4</sub>) 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 Fe<sub>3</sub>O<sub>4</sub> 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 Fe<sub>3</sub>O<sub>4</sub> crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe<sub>3</sub>O<sub>4</sub> 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 Fe<sub>3</sub>O<sub>4</sub>. 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 Fe<sub>3</sub>O<sub>4</sub> nanoparticles and PVDF/PMMA-Fe<sub>3</sub>O<sub>4</sub> nanocomposites. The values of saturation magnetization for pure Fe<sub>3</sub>O<sub>4</sub> are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe<sub>3</sub>O<sub>4</sub> content.
文摘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.
文摘In this work, an efficient way of converting the water hyacinth <span style="font-family:Verdana;">to</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> biocrude oil usi</span><span style="font-family:Verdana;">ng magnetite nanoparticles (MNPs) as potential catalysts was demo</span><span style="font-family:Verdana;">nstrated 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</span></span><span style="font-family:Verdana;">—</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">320</span><span style="font-family:Verdana;"><img src="Edit_b832a078-c9f1-4a9c-871e-2ed1f0c6e7ac.png" alt="" /></span><span style="font-family:Verdana;">, reaction time</span><span style="font-family:Verdana;">—</span><span style="font-family:;" "=""><span style="font-family:Verdana;">60 minutes, MNPs to biomass ratio – 0.2 g/g and bioma</span><span style="font-family:Verdana;">ss to water ratio – 0.06 g/g. HTL in presence of MNPs gave high</span><span style="font-family:Verdana;">er 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</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">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.</span>
基金funding from the Ministry of Education,Culture,Research,and Technology,Indonesia,through the PDKN Research Grant with Contract No.041/E5/PG.02.00.PL/2023.
文摘Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems that must be resolved.To this end,a drug carrier incorporating natural magnetic cores in a zeolite framework was developed and applied to the loading of curcumin in ethanol solutions.In this system,curcumin is encapsulated in a zeolite Na(ZNA)magnetic core–shell structure(Fe@Si/ZNA),which can be easily synthesized using an in situ method.Synthesis of Fe_(3)O_(4) nanoparticles was carried out from natural materials using a co-precipitation method.Analysis of the prepared magnetic core–shell structures and composites was carried out using vibrating-sample magnetometery,Fourier transform infrared spectroscopy,transmission electron microscopy,and x-ray diffraction.The cumulative loading of curcumin in the ZNA composite with 9%nanoparticles was found to reach 90.70%with a relatively long half-life of 32.49 min.Stability tests of curcumin loading in the composite showed that adding magnetic particles to the zeolite framework also increased the stability of the composite structure.Adsorption kinetics and isotherm studies also found that the system follows the pseudo-second-order and Langmuir isotherm models.