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 ch...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.展开更多
The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The ef...The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.展开更多
Cross-linkedβ-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe3O4 nanoparti...Cross-linkedβ-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe3O4 nanoparticles inβ-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent.The morphology,structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy（TEM）,Fourier transform infrared（FTIR） spectrometry,X-ray diffraction（XRD） measurement,thermogravimetric analysis（TGA） and Vibrating sample magnetometry （VSM）,respectively.展开更多
Novel magnetic core/shell bimetallic Au/Cu nanoparticles（Fe_3O_4@SiO_2-Au/Cu NPs） were prepared using SiO_2-coated iron oxide（Fe_3O_4@SiO_2） as a supported material. The magnetic Fe_3O_4 colloidal nanocrystal clus...Novel magnetic core/shell bimetallic Au/Cu nanoparticles（Fe_3O_4@SiO_2-Au/Cu NPs） were prepared using SiO_2-coated iron oxide（Fe_3O_4@SiO_2） as a supported material. The magnetic Fe_3O_4 colloidal nanocrystal clusters（CNCs） as nano-core were modified with a silica coating for improvement stability and superficial area of the Au-Cu particles. The morphological structure and chemical composition of the Fe_3O_4@SiO_2-Au/Cu NPs were characterized with high-resolution transmission electron microscopy（HRTEM）, energy-dispersive X-ray（EDX） and X-ray photoelectron spectroscopy（XPS） analyses. The Au and Cu NPs were deposited on the SiO_2 surface in a highly dense and well dispersed manner with an average size of approximately 5 nm. The Fe_3O_4@SiO_2-Au/Cu NPs as magnetic nano-catalysts were applied to the Ullmann coupling reaction of bromamine acid to synthesize 4,40-diamino-1,10-dianthraquinonyl-3,30-disulfonic acid（DAS）. The prepared Fe_3O_4@SiO_2-Au/Cu NPs exhibited efficient catalytic activity with higher conversion and selectivity. A bromamine acid conversion of 97.35% and selectivity for DAS of 88.67% were obtained in aqueous medium. The magnetic nano-catalysts can be readily separated from the reaction system and reused. This new nano-catalytic reaction represents a useful and attractive cleaner production system. The new catalyst system has important and potential applications in dye and pigment industry.展开更多
Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale...Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution p H, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the p H range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe3O4 MNP dose up to 1.0 g·L-1and with H2O2 concentration until reaching the maximum. Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.展开更多
In this paper,chemical co-precipitation method was employed to synthesize Fe3O4 nanoparticles which can be well dispersed in water by using citric acid as a surfactant.Afterwards,by using Fe3O4 nanoparticles as seeds ...In this paper,chemical co-precipitation method was employed to synthesize Fe3O4 nanoparticles which can be well dispersed in water by using citric acid as a surfactant.Afterwards,by using Fe3O4 nanoparticles as seeds in a Triton X-100/hexanol/cyclohexane/water reverse microemulsion system,the core-shell structural Fe3O4@SiO2 nanocomposite particles were prepared via hydrolysis and condensation of tetraethyl orthosilicate(TEOS) under the catalysis of alkali.The effects of different stirring methods and the concentration of TEOS on the morphology of Fe3O4@SiO2 nanoparticles were investigated.The results show that the mechanical stirring can effectively control the morphology of composite nanoparticles to form a good dispersion and spherical morphology of core-shell nanoparticles.With the increase of TEOS concentration,the thickness of the SiO2 shell increases,and the morphology of the composite particles becomes more uniform.展开更多
A magnetic sensor for detection of Pb^2＋ has been developed based on Fe/Fe3O4 nanoparticles modified by3-（3,4-dihydroxyphenyl）propionic acid（DHCA）. The carboxyl groups of DHCA have a strong affinity to coordinati...A magnetic sensor for detection of Pb^2＋ has been developed based on Fe/Fe3O4 nanoparticles modified by3-（3,4-dihydroxyphenyl）propionic acid（DHCA）. The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb^2＋ thus inducing the transformation of Fe/Fe3O4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time（T2） of the surrounding water protons. Upon addition of the different concentrations of Pb^2＋ to an aq. solution of DHCA functionalized Fe/Fe3O4 nanoparticles（DHCA-Fe/Fe3O4 NPs）（[Fe] = 90 mmol/L）, the change of T2 values display a good linear relationship with the concentration of Pb^2＋ from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb^2＋, DHCA-Fe/Fe3O4 NPs exhibited a high selectivity over other metal ions.展开更多
We herein used Fe3O4 nanoparticles（NPs） as an adsorption interface for the concurrent removal of gaseous benzene, toluene, ethylbenzene and m-xylene（BTEX） and sulfur dioxide（SO2）, at different relative humiditie...We herein used Fe3O4 nanoparticles（NPs） as an adsorption interface for the concurrent removal of gaseous benzene, toluene, ethylbenzene and m-xylene（BTEX） and sulfur dioxide（SO2）, at different relative humidities（RH）. X-ray diffraction, Brunauer-Emmett-Teller, and transmission electron microscopy were deployed for nanoparticle surface characterization.Mono-dispersed Fe3O4（Fe2O3·Fe O） NPs synthesized with oleic acid（OA） as surfactant, and uncoated poly-dispersed Fe3O4 NPs demonstrated comparable removal efficiencies.Adsorption experiments of BTEX on NPs were measured using gas chromatography equipped with flame ionization detection, which indicated high removal efficiencies（up to（95 ± 2）%） under dry conditions. The humidity effect and competitive adsorption were investigated using toluene as a model compound. It was observed that the removal efficiencies decreased as a function of the increase in RH, yet, under our experimental conditions, we observed（40 ± 4）% toluene removal at supersaturation for Fe3O4 NPs, and toluene removal of（83 ± 4）% to（59 ± 6）%, for OA-Fe3O4 NPs. In the presence of SO2, the toluene uptake was reduced under dry conditions to（89 ± 2）% and（75 ± 1）% for the uncoated and coated NPs, respectively, depicting competitive adsorption. At RH 〉 100%,competitive adsorption reduced the removal efficiency to（27 ± 1）% for uncoated NPs whereas OA-Fe3O4 NPs exhibited moderate efficiency loss of（55 ± 2）% at supersaturation.Results point to heterogeneous water coverage on the NP surface. The magnetic property of magnetite facilitated the recovery of both types of NPs, without the loss in efficiency when recycled and reused.展开更多
文摘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.
基金Project(2013DFA51290)supported by International S&T Cooperation Program of China
文摘The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.
基金financially supported by the Guangdong Natural Science Foundation(No.020891)
文摘Cross-linkedβ-cyclodextrin polymer/Fe3O4 composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe3O4 nanoparticles inβ-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent.The morphology,structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy（TEM）,Fourier transform infrared（FTIR） spectrometry,X-ray diffraction（XRD） measurement,thermogravimetric analysis（TGA） and Vibrating sample magnetometry （VSM）,respectively.
基金financially supported by the Shanghai Natural Science Foundation (No. 13ZR1400300)National Key R&D Program of China (No. 2017YFB030900)
文摘Novel magnetic core/shell bimetallic Au/Cu nanoparticles（Fe_3O_4@SiO_2-Au/Cu NPs） were prepared using SiO_2-coated iron oxide（Fe_3O_4@SiO_2） as a supported material. The magnetic Fe_3O_4 colloidal nanocrystal clusters（CNCs） as nano-core were modified with a silica coating for improvement stability and superficial area of the Au-Cu particles. The morphological structure and chemical composition of the Fe_3O_4@SiO_2-Au/Cu NPs were characterized with high-resolution transmission electron microscopy（HRTEM）, energy-dispersive X-ray（EDX） and X-ray photoelectron spectroscopy（XPS） analyses. The Au and Cu NPs were deposited on the SiO_2 surface in a highly dense and well dispersed manner with an average size of approximately 5 nm. The Fe_3O_4@SiO_2-Au/Cu NPs as magnetic nano-catalysts were applied to the Ullmann coupling reaction of bromamine acid to synthesize 4,40-diamino-1,10-dianthraquinonyl-3,30-disulfonic acid（DAS）. The prepared Fe_3O_4@SiO_2-Au/Cu NPs exhibited efficient catalytic activity with higher conversion and selectivity. A bromamine acid conversion of 97.35% and selectivity for DAS of 88.67% were obtained in aqueous medium. The magnetic nano-catalysts can be readily separated from the reaction system and reused. This new nano-catalytic reaction represents a useful and attractive cleaner production system. The new catalyst system has important and potential applications in dye and pigment industry.
基金Supported by the National Natural Science Foundation of China(51009115)Shaanxi Provincial Department of Education Key Laboratory Project(13JS067)+2 种基金the Hall of Shaanxi Province Science and Technology(2013JK0881)the Research Plan Project of Water Resources Department of Shaanxi Province(2013slkj-07)the Innovation of Science and Technology Fund of Xi'an University of Technology(211302)
文摘Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution p H, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the p H range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe3O4 MNP dose up to 1.0 g·L-1and with H2O2 concentration until reaching the maximum. Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.
文摘In this paper,chemical co-precipitation method was employed to synthesize Fe3O4 nanoparticles which can be well dispersed in water by using citric acid as a surfactant.Afterwards,by using Fe3O4 nanoparticles as seeds in a Triton X-100/hexanol/cyclohexane/water reverse microemulsion system,the core-shell structural Fe3O4@SiO2 nanocomposite particles were prepared via hydrolysis and condensation of tetraethyl orthosilicate(TEOS) under the catalysis of alkali.The effects of different stirring methods and the concentration of TEOS on the morphology of Fe3O4@SiO2 nanoparticles were investigated.The results show that the mechanical stirring can effectively control the morphology of composite nanoparticles to form a good dispersion and spherical morphology of core-shell nanoparticles.With the increase of TEOS concentration,the thickness of the SiO2 shell increases,and the morphology of the composite particles becomes more uniform.
基金supported by National Natural Science Foundation of China (Nos. 21271130 and 21371122)Shanghai Science and Technology Development Fund (Nos. 12ZR1421800 and 13520502800)International Joint Laboratory on Resource Chemistry (IJLRC)
文摘A magnetic sensor for detection of Pb^2＋ has been developed based on Fe/Fe3O4 nanoparticles modified by3-（3,4-dihydroxyphenyl）propionic acid（DHCA）. The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb^2＋ thus inducing the transformation of Fe/Fe3O4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time（T2） of the surrounding water protons. Upon addition of the different concentrations of Pb^2＋ to an aq. solution of DHCA functionalized Fe/Fe3O4 nanoparticles（DHCA-Fe/Fe3O4 NPs）（[Fe] = 90 mmol/L）, the change of T2 values display a good linear relationship with the concentration of Pb^2＋ from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb^2＋, DHCA-Fe/Fe3O4 NPs exhibited a high selectivity over other metal ions.
基金the support of the following Canadian funding agencies: NSERC, FRQNT and CFI
文摘We herein used Fe3O4 nanoparticles（NPs） as an adsorption interface for the concurrent removal of gaseous benzene, toluene, ethylbenzene and m-xylene（BTEX） and sulfur dioxide（SO2）, at different relative humidities（RH）. X-ray diffraction, Brunauer-Emmett-Teller, and transmission electron microscopy were deployed for nanoparticle surface characterization.Mono-dispersed Fe3O4（Fe2O3·Fe O） NPs synthesized with oleic acid（OA） as surfactant, and uncoated poly-dispersed Fe3O4 NPs demonstrated comparable removal efficiencies.Adsorption experiments of BTEX on NPs were measured using gas chromatography equipped with flame ionization detection, which indicated high removal efficiencies（up to（95 ± 2）%） under dry conditions. The humidity effect and competitive adsorption were investigated using toluene as a model compound. It was observed that the removal efficiencies decreased as a function of the increase in RH, yet, under our experimental conditions, we observed（40 ± 4）% toluene removal at supersaturation for Fe3O4 NPs, and toluene removal of（83 ± 4）% to（59 ± 6）%, for OA-Fe3O4 NPs. In the presence of SO2, the toluene uptake was reduced under dry conditions to（89 ± 2）% and（75 ± 1）% for the uncoated and coated NPs, respectively, depicting competitive adsorption. At RH 〉 100%,competitive adsorption reduced the removal efficiency to（27 ± 1）% for uncoated NPs whereas OA-Fe3O4 NPs exhibited moderate efficiency loss of（55 ± 2）% at supersaturation.Results point to heterogeneous water coverage on the NP surface. The magnetic property of magnetite facilitated the recovery of both types of NPs, without the loss in efficiency when recycled and reused.
