基于原子转移自由基聚合的PGMA-b-PDMAEMA嵌段共聚物接枝磁性纳米粒上的脂肪酶固定化（英文）

A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.

RhB Adsorption Performance of Magnetic Adsorbent Fe_3O_4/RGO Composite and Its Regeneration through A Fenton-like Reaction

Adsorption is one of the most effective technologies in the treatment of colored matter containing wastewater. Graphene related composites display potential to be an effective adsorbent. However, the adsorption mechanism and their regeneration approach are still demanding more efforts. An effective magnetically separable absorbent, Fe3O4 and reduced graphene oxide(RGO) composite has been prepared by an in situ coprecipitation and reduction method. According to the characterizations of TEM, XRD, XPS, Raman spectra and BET analyses, Fe3O4 nanoparticles in sizes of 10-20 nm are well dispersed over the RGO nanosheets, resulting in a highest specific area of 296.2 m2/g. The rhodamine B adsorption mechanism on the composites was investigated by the adsorption kinetics and isotherms. The isotherms are fitting better by Langmuir model, and the adsorption kinetic rates depend much on the chemical components of RGO. Compared to active carbon, the composite shows 3.7 times higher adsorption capacity and thirty times faster adsorption rates. Furthermore,with Fe3O4 nanoparticles as the in situ catalysts, the adsorption performance of composites can be restored by carrying out a Fenton-like reaction, which could be a promising regeneration way for the adsorbents in the organic pollutant removal of wastewater.

N-doped porous carbon hollow microspheres encapsulated with iron-based nanocomposites as advanced bifunctional catalysts for rechargeable Zn-air battery

The design and development of low-cost,efficient,and stable bifunctional electrocatalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desirable for rechargeable metal-air batteries.In this work,N-doped porous hollow carbon spheres encapsulated with ultrafine Fe/Fe3O4 nanoparticles(FeOx@N-PHCS)were fabricated by impregnation and subsequent pyrolysis,using melamine-formaldehyde resin spheres as self-sacrifice templates and polydopamine as N and C sources.The sufficient adsorption of Fe3+on the polydopamine endowed the formation of Fe-Nx species upon high-temperature carbonization.The prepared FeOx@N-PHCS has advanced features of large specific surface area,porous hollow structure,high content of N dopants,sufficient Fe-Nx species and ultrafine FeOx nanoparticles.These features endow FeOx@N-PHCS with enhanced mass transfer and considerable active sites,leading to high activity and stability in catalyzing ORR and OER in alkaline electrolyte.Furthermore,the rechargeable Zn-air battery with FeOx@N-PHCS as air cathode catalyst exhibits a large peak power density,narrow charge-discharge potential gap and robust cycling stability,demonstrating the potential of the fabricated FeOx@N-PHCS as a promising electrode material for metal-air batteries.This new finding may open an avenue for rational design of bifunctional catalysts by integrating different active components within all-in-one catalyst for different electrochemical reactions.

Surface Organic Modification of Fe_3O_4 Magnetic Nanoparticles

The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer＇s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.

Design and Fabrication of Superparamaganitic Hybrid Microspheres for Protein Immobilization

Superparamagnetic poly（styrene）-co-poly（2-acrylanmido-2-methyl propanesulfonic acid） （PSt-co-PAMPS） and poly（methylmethacrylate）-co-poly（glycidyl methacrylate） （PMMA-co-PGMA） microspheres with mean size of 170 nm were prepared by emulsion polymerization in the presence of oleic acid-coated Fe3O4 nanoparticles. The structures, morphologies, diameter and diameter distribution of the as-prepared microspheres were identified by Fourier transform infrared spectroscopy （FT-IR） and transmission electron microscopy （TEM）. The saturation magnetizations of PSt-co-PAMPS and PMMA-co-PGMA microspheres are 21.94 and 25.07 emu/g, respectively. The as-synthesized magnetic microspheres were used for immobilization of Bovine serum albumin （BSA） by physical interaction and covalent interaction respectively. The equilibrium amount of BSA immobilized onto PMMA-co-PGMA microspheres was 86.48 mg/g microspheres in 90 min, while on PSt-co-PAMPS microspheres was 59.62 mg/g microspheres in 120 min.

Controlling the Properties of Solvent-free Fe_3O_4 Nanofluids by Corona Structure

We studied the relationship between corona structure and properties of solvent-free Fe3O4 nanofluids. We proposed a series of corona structures with different branched chains and synthesize different solvent-free nanofluids in order to show the effect of corona structure on the phase behavior, dispersion, as well as rheology properties. Results demonstrate novel liquid-like behaviors without solvent at room temperature. Fe3O4 magnetic nanoparticles content is bigger than 8% and its size is about 23 nm. For the solvent-free nanofluids,the long chain corona has the internal plasticization, which can decrease the loss modulus of system, while the short chain of corona results in the high viscosity of nanofluids. Long alkyl chains of modifiers lead to lower viscosity and better flowability of nanofluids. The rheology and viscosity of the nanofluids are correlated to the microscopic structure of the corona, which provide an in-depth insight into the preparing nanofluids with promising applications based on their tunable and controllable physical properties.

Fe_3O_4 Magnetic Nanoparticles Modified Electrode as a Sensor for Determination of Nimesulide

A novel type of Fe3O4 nanoparticles modified glass carbon electrode（Fe3O4/GCE） was constructed and the electrochemical properties of N-（4-nitro-2-phenoxyphenyl）methanesulfonamide（nimesulide） were studied on the Fe3O4/GCE.In 0.4mol/L HAc-NaAc buffer solution（pH=5.0）,the electrode process of nimesulide was irreversible at bare GCE and Fe3O4/GCE.The Fe3O4/GCE exhibited a remarkable catalytic and enhancement effect on the reduction of nimesulide.The reduction peak potential of nimesulide shifted positively from-0.683 V at bare GCE to-0.625 V at Fe3O4/GCE,and the sensitivity was increased by ca.3 times.Some experimental conditions were optimized.The linear range between the peak current and the concentration of nimesulide was 2.6×10-6 ＂1.0×10-4mol/L（R=0.993） with a detection limit of 1.3×10-7mol/L.This method has been used to determine the content of nimesulide in medical tablets.The recovery was determined to be 96.9% ＂101.9% by means of standard addition method.The method is comparable to UV-Vis spectrometry.

Modification of Fe_3O_4 Magnetic Nanoparticles by L-dopa or Dopamine as an Enzyme Support

Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin （EC： 3.4.21.4） on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.

Gap-plasmon of Fe3O4@Ag Core-shell Nanostructures for Highly Enhanced Fluorescence Detection of Rhodamine B

A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.

Synthesis of Magnetically Modified Fe-Al Pillared Bentonite and Heterogeneous Fenton-like Degradation of Orange II

Magnetically modified Fe-Al pillared bentonite（Fe3O4/ Fe-Al-Bent） was prepared via chemical co-precipitation method and characterized by powder X-ray diffraction（XRD）, Brunauer-EmmettTeller（BET）, Fourier transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. A series of experiments were carried out to investigate the degradation of Orange II by the obtained heterogeneous catalysts in the presence of H2O2. The experimental result indicated that the synthetic materials had a high catalytic activity and good reusability.

Controllable Synthesis and Magnetic Properties of Monodisperse Fe_3O_4 Nanoparticles

Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.

Determination of Anionic Surfactants in Environmental Water Samples Using Fluorescence Enhancement Method Based on Fe_3O_4@PAA-RB Fluorescent Nanoparticles

[ Objective] The study aims at developing a novel fluorescence enhancement method to determine anionic surfactants. [ Method] Based on Fe3O4 @ PAA-RB fluorescent nanoparticles as fluorescent probes, we have developed a novel fluorescence enhancement method for the determi- nation of an anionic surfactant sodium dodecyl sulfate （SDS） through the gradual optimization of experiment conditions. [ Result] Under the opti- mum conditions, the extent of fluorescence enhancement is directly proportional to SDS concentration varying from 0.5 to 16.0 μmol/L, and the de- tection limit reaches 0.051 μmol/L. The relative standard deviation （RSD） for 4.0 μmol/L SDS is 3.3% （ n =6）. The proposed method has been successfully applied to the determination of SDS in environmental water samples, with recovery of 96.3% -105.5%. E Conclusion] The novel fluo- rescence enhancement method is not only simple and rapid, but also has avoided using tedious solvent-extraction and toxic organic solvents.

Preparation and characterization of cross-linked β-cyclodextrin polymer/Fe_3O_4 composite nanoparticles with core-shell structures

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.

Novel coprecipitation-oxidation method for recovering iron from steel waste pickling liquor

Waste pickling liquors （WPLs） containing high concentrations of iron and acid are hazardous waste products from the steel pickling processes. A novel combined coprecipitation-oxidation method for iron recovery by Fe304 nanoparhcle＇ production from the WPLs was developed in this study. 2＋All oxidation-reduction potential monitoring method was developed for real-time control of the Fe2＋/Fe3＋ molar ratio. The key coprecipitation-oxidation parameters were determined using the orthogonal experimental design method. The use of promoters greatly improved the Fe3O4 nanoparticle crystallinity, size, magnetization, and dispersion. X-ray diffraction patterns showed that the produced Fe3O4. nanoparticles were single phase. The Fe3O4 nan oparticles were approximately spherical and slightly aggtomerated. Vibrating sample magnetometry showed that the Fe3O4 nanopahicles produced from the WPLs had good magnetic properties, with a saturation magnetization of 80.206 emu. g-1 and a remanence of 10.500 emu. g-1. The results show that this novel coprecipitation-oxidation method has great potential for recycling iron in WPLs.

A highly selective magnetic sensor with functionalized Fe/Fe_3O_4 nanoparticles for detection of Pb^(2+)

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.

Degradation of 2,4-DCP by the Immobilized Laccase on the Carrier of Fe304@SiO2-NH2

In this paper, the laccase immobilized on Fe304@SiO2-NH2 nanoparticles was successfully prepared by the glutaraldehyde cross-linking method. The degradations of 2,4-diehlorophenol （2,4-DCP） catalyzed by laccase and immobilized laccase were carried out. The optimal conditions regarding degradation efficiency were also discussed, which include reaction time, pH value, temperature, concentration of 2,4-DCP and laccase. When laccase was immobilized on Fe304@SiO2-NH2 carrier by crosslinking with glutaraldehyde, the stability and repetition were im- proved significantly. The removal efficiency of 2,4-DCP by immobilized laccase still remained over 59% after six cycles of operation. Degradation of 2,4-DCP is a first-order reaction and the activation energies of 2,4-DCP catalyzed by laccase and immobilized laccase are 51.93 kJ·mol-1 strate the immobilized laccase had a faster degradation Fe304@MSS-NH2 can promote the degradation reaction. and 44.12 kJ·mol-1, respectively. The results demonrate than the free laccase; the magnetic carrier

Enhancement of Fe3O4/Au Composite Nanoparticles Catalyst in Oxidative Degradation of Methyl Orange Based on Synergistic Effect

Enhancement of Fe3O4/Au nanoparticles （Fe3O4/Au NPs） catalyst was observed in the oxidative degradation of methyl orange by employing H2O2 as oxidant. To evaluate the catalytic activity of Fe3O4/Au nanoparticles, different degradation conditions were investigated such as the amounts of catalyst, H2O2 concentration and pH value. Based on our data, methyl orange was degraded completely in a short time. The enhanced catalytic activity and increased oxidation rate constant may be ascribed to synergistic catalyst-activated decomposition of H2O2 to ,OH radical, which was one of the strong oxidizing species. Besides, Fe3O4/Au nanoparticles have exhibited satisfying recycle performance for potential industrial application.

Application of response surface methodology for optimization of Orange Ⅱ removal by heterogeneous Fenton-like process using Fe_3O_4nanoparticles

In this study, Fe3O4nanoparticles（Fe3O4NPs） were successfully prepared via oxidation–precipitation method and characterized by scanning electron microscopy（SEM）, X-ray diffraction（XRD） and Fourier transform infrared spectroscopy（FT-IR）. The characterization results indicated that Fe3O4 NPs with regular crystal structure and a narrow of diameters had been synthesized successfully and had high purity. A series of experiments were carried out to investigate the degradation of Orange II by the obtained heterogeneous Fe3O4 catalysts in the presence of H2O2. The response surface methodology（RSM） based on Box–Behnken design（BBD） was employed to design and optimize individual and interactive effects of the four main independent parameters（catalyst loading, initial p H, reaction temperature and H2O2concentration） on decolorization efficiency of Orange II. A significant quadratic model（p-value 〈0.0001, R2= 0.9369） was derived using analysis of variance（ANOVA）. Optimum conditions were catalyst loading of 1.5 g/L, initial p H of 2.7, reaction temperature of 42 8C and H2O2 concentration of 22 mmol/L, respectively. The predicted decolorization rate under the optimum conditions as determined by the proposed model was 99.55%. Confirmatory tests were carried out and the decolorization rate of 99.49% was observed under the optimum conditions, which agreed well with the model prediction.

Co-adsorption of gaseous benzene, toluene, ethylbenzene,m-xylene(BTEX) and SO_2 on recyclable Fe_3O_4 nanoparticles at 0–101% relative humidities

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.

Magnetic CuO nanoparticles supported on graphene oxide as an efficient catalyst for A^3-coupling synthesis of propargylamines

Magnetically separable CuO nanoparticles supported on graphene oxide（Fe3O4 NPs/GO-CuO NPs） is synthesized and characterized for the preparation of propargylamines in EtOH,at 90 C.Fe3O4 NPs/GOCuO NPs is found to be an efficient catalyst for the A^3-coupling of aldehydes,amines,and alkynes through C-H activation.Both aromatic and aliphatic aldehydes and alkynes are combined with secondary amines to provide a wide range of propargylamines in moderate to excellent yields.