Adsorption of BSA on Carbon-coated Fe_3O_4 Microspheres Activated with 1-ethyl-3-(3-dimethylaminopropyl)-Carbodiimide Hydrochloride

Carbon-coated Fe3O4（ Fe3O4/C） microspheres activated with 1-ethyl-3-（3-dimethylaminopropyl）-carbodiimide hydrochloride（EDC） were prepared, characterized and applied to adsorb bovine serum albumin（BSA）. The prepared magnetic microspheres had spherical core-shell structure with a uniform and continuous carbon coating coupled with activation by EDC, and possessed superparamagnetic characteristics. The experimental results showed that the adsorption amount of BSA on the EDC-activated Fe3O4/C（Fe3O4/C-EDC） microspheres was higher than that on the Fe3O4/C microspheres. The maximum adsorption of BSA on Fe3O4/C-EDC microspheres occurred at pH 4.7, which was the isoelectric point of BSA. At low concentrations（below 1.0 M）, salt had no noticeable effect on BSA adsorption. The BSA adsorption of Fe3O4/C-EDC microspheres had a better fit to the Langmuir model than the Freundlich isotherm and Temkin isotherm model, and the kinetic data were well described by the pseudo-second-order model. The adsorption equilibrium could be reached within 20 min. High desorption efficiency（97.6%） of BSA from Fe3O4/C-EDC microspheres was obtained with 0.5 M Na2HPO4（pH 9.4） as the desorbent.

Electrochemical Sensing of Heavy Metal Ions based on Monodisperse Single-crystal Fe_3O_4 Microspheres

Single-crystal FeOwith monodisperse microspheres structure has been used for individual electrochemical detection of heavy metal ions. Morphology and structure of the as-prepared FeOmicrospheres were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffraction(XRD). Meanwhile the electrochemical properties of the FeOmicrospheres modified glass carbon electrodes(GCE) were characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS), and the enhanced electrochemical response in stripping voltammetry for individual detection of Pb(Ⅱ), Hg(Ⅱ), Cu(Ⅱ), and Cd(Ⅱ) was evaluated using square wave anodic stripping voltammetry(SWASV). With high specific surface area and excellent catalytic activity toward heavy metal ions, the as-prepared monodisperse and single-crystal FeOmicrospheres show a preferable sensing sensitivity(22.2 μA/μM) and limit of detection(0.0699 μM) toward Pb(Ⅱ). Furthermore, the electrochemical sensor of FeOmicrospheres exhibits excellent stability and it also offers potential practical applicability for the determination of heavy metal ions in real water samples. This study provides a potential simple and low cost iron oxide for the construction of sensitive electrochemical sensors applied to monitor and control the pollution of toxic metal ions.

磁性Fe_3O_4亚微米球固相萃取-HPLC检测水中植物生长调节剂残留

建立了水中2,4-二氯苯氧乙酸(2,4-D)、萘乙酸(NAA)和6-苄基腺嘌呤(6-BA)3种植物生长调节剂残留分析的高效液相色谱方法。采用溶剂热还原法,以乙二醇和FeCl3.6H2O作原料,合成出形貌均一、分散性好、稳定性佳的磁性Fe3O4亚微米球,作为固相萃取材料,以静电吸附作用可以富集水中残留的2,4-D、NAA、6-BA 3种植物生长调节剂。水样经调节pH值和固相萃取净化后,高效液相色谱法测定。3种植物生长调节剂在0.1～10 mg/L范围内响应和浓度的线性关系良好,相关系数均大于0.999;2,4-D、NAA、6-BA的检测限分别为0.06、0.02、0.04 mg/L。在测定的自来水、河水和湖水3种水样中,添加回收率范围为73.20%～87.21%,相对标准偏差为1.11%～7.52%(n=3),为水中的2,4-D、NAA和6-BA残留监控提供了简单、快速、准确的测定方法。

Magnetically Recoverable PEI/Titanate@Fe_3O_4 Photocatalysts: Fabrication and Photocatalytic Properties

The magnetically separable ternary polyetherimide/titanate@Fe3O4(PTF) photocatalysts of special heterostructure between magnetite(Fe3O4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe3O4microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3 D microsphere and 2 D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe3O4microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe3O4microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe3O4microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5(96.7%) over 3 times reuse.

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.

Preparation and mechanism of Fe_3O_4/Au core/shell super-paramagnetic microspheres

In the presence of Fe3O4 nano-particles, a new type of super-paramagnetic Fe3O4/Au microspheres with core/shell structures was prepared by reduction of Au3+ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe3O4 added and the initial concentration of Au3+. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased, and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres are of an average diameter of 180 nm, a little bit larger than those before coating.

2D nanoplate assembled nitrogen doped hollow carbon sphere decorated with Fe3O4 as an efficient electrocatalyst for oxygen reduction reaction and Zn-air batteries

Designing a highly efficient non-precious based oxygen reduction reaction(ORR)electrocatalyst is critical for the commercialization of various sustainable energy storage and conversion devices such as metal-air batteries and fuel cells.Herein,we report a convenient strategy to synthesis Fe3O4 embedded in N doped hollow carbon sphere(NHCS)for ORR.What's interesting is that the carbon microsphere is composed of two-dimensional(2D)nanoplate that could provide more exposed active sites.The usage of solid ZnO nanowires as zinc source is crucial to obtain this structure.The Fe3O4@NHCS-2 exhibits better catalytic activity and durability than the commercial PtC catalyst.Moreover,it further displays high-performance of Zn-air batteries as a cathode electrocatalyst with a high-power density of 133 mW·cm^-2 and high specific capacity of 701 mA·h·g^-1.The special hollow structure composed 2D nanoplate,high surface area,as well as synergistic effect between the high active Fe3O4 nanoparticles and N-doped matrix endows this outstanding catalytic activity.The work presented here can be easily extended to prepare metal compounds decorated carbon nanomaterials with special structure for a broad range of energy storage and conversion devices.

PREPARATION OF COMPOSITE MAGNETIC MICROSPHERES BY REACTIVE BLENDING

A novel method for preparation of polymer-based magnetic microspheres was proposed by utilizing melt reactive blending, which was based on selective location of Fe3O4 nanoparticles in PA6 domains of polystyrene （PS）/polyamide 6 （PA6） immiscible blends. The morphology of PA6/Fe3O4 composite magnetic mierospheres was studied by scanning electronic microscopy （SEM）. The composite magnetic mierospheres were spherical with a diameter range of 0.5-8 μm; the diameter was sharply decreased with a very narrow distribution by adding terminal maleic anhydride fimctionalized polystyrenes （FPS） for reactive blending. Transmission electron microscopy （TEM） and thermogravimetry analysis （TGA） results showed that most of Fe3O4 was located in the PA6 microspheres. Magnetization data revealed the magnetite content of PA6/Fe3O4 microspheres was about 32 wt% and the saturation magnetization could be up to 17.2 AmE/kg.

改性海藻酸钠微球对Pb2+吸附性能的研究

文章以海藻酸钠(SA)为原料,与羧基化微晶纤维素(CCN)、四氧化三铁(Fe3O4)进行溶液共混,采用化学沉淀法制备出Fe3O4@CCN/SA复合微球。以硝酸铅溶液为研究对象,探讨了初始浓度、pH、吸附时间对吸附性能的影响。结果表明:Pb2+浓度为1 000mg/L,pH=5,吸附时间为6 h时,饱和吸附量最大为184.2 mg/g。吸附符合Langmuir等温线模拟和拟二级反应动力学模型。该磁性微球使用盐酸解析脱附,重复使用第6次饱和吸附量仍高达165.5 mg/g,说明Fe3O4@CCN/SA磁性微球具有良好的再生使用性能。

微米球四氧化三铁的水热合成和对铅离子的吸附研究

本文以FeCl3•6H2O,Na3C6H5O7•2H2O为反应原料,水热法合成Fe3O4微米球。通过X射线衍射(XRD)、扫描电镜(SEM)和傅里叶红外光谱(FTIR)对Fe3O4进行表征。研究了Fe3O4微米球对Pb2+的吸附特性,并使用等温模型、吸附动力学和吸附热力学模型分析吸附机理。结果表明,Fe3O4微米球对Pb2+的吸附过程符合Freundlich等温吸附模型和准二级动力学模型。热力学参数表明对Pb2+的吸附过程是自发和吸热过程。在25℃,pH为6的条件下,对Pb2+的最大吸附容量是74.5 mg•g−1。