RSC Advances
·
2016
·Vol. 6
·期 13
·10633-10640
·
IF 3.289
Chao Sun,Rui Zhou,Jianan E,Jiaqiang Sun,Yu Su,Hejun Ren
Magnetic nanoscaled ascorbic acid/magnetite (H2A/Fe3O4) composite was prepared by oxidative polymerization and proposed as a novel heterogeneous catalyst of persulfate (PS) for improved degradation of 2,4-dichlorophenol (2,4-DCP). The composite was fully characterized and evaluated in terms of catalytic activity, effect of reaction parameters, iron ion leaching, and identification of primary reaction oxidants, as well as the possible role of H2A. The degradation efficiency of 2,4-DCP reached 98.5% within 150 min using the H2A/Fe3O4 nanocomposite compared with only 35.1% under the same conditions for pure nano Fe3O4. This result indicated an enhancement in the performance of activated PS. The findings of this study provide some new insights into the potential of using H2A to enhance the performance of Fe3O4 nanoparticles in the activation of PS for improving the degradation of organic pollutants.
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Analytical Methods
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2017
·Vol. 9
·期 37
·5509-5517
·
IF 1.9
Keqin Deng,Xinyan Liu,Chunxiang Li,Zhaohui Hou,Haowen Huang
No work studied and compared Fe3O4-functionalized carbon-based nanomaterials. Also, no work investigated their application for detecting bisphenol A (BPA), an important organic chemical raw material, which had been proved to cause malformation, cancers, sexual precocity, and neural and behavioral changes in infants and children. In this work, Fe3O4 magnetite nanoparticles were stably anchored on carbon materials to synthesize three types of nanohybrids, i.e. hybrids of graphene oxide with Fe3O4 (GO–Fe3O4), carbon nanotubes with Fe3O4 (CNTs–Fe3O4), and graphene oxide and carbon nanotubes with Fe3O4 (GO–CNTs–Fe3O4). These nanohybrids were characterized using a transmission electron microscope (TEM), X-ray diffractometer (XRD), and Fourier transform infrared spectrometer (FT-IR). GO–Fe3O4, CNTs–Fe3O4, and GO–CNTs–Fe3O4 were immobilized on the surface of a GCE using electro-poly(glutamic acid). The electrochemical response characteristic of bisphenol A (BPA) on different modified electrodes was investigated by cyclic voltammetry. It showed that these three types of nanohybrids greatly enhanced the anodic peak current of BPA. Then, these hybrids were applied to determine BPA by differential pulse voltammetry. Their determination performance was compared with each other. Among them, the GO–CNTs–Fe3O4 modified electrode exhibited wider linear ranges of 0.003–0.2 and 0.2–30.0 μmol L−1 with a lower estimated detection limit of 1.0 nmol L−1.
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ANALYTICA CHIMICA ACTA
·
2016
·
IF 4.712
Pei Liu,Kexin Zhang,Ranran Zhang,Huanshun Yin,Yunlei Zhou,Shiyun Ai
Abnormal level of DNA methyltransferase (MTase) – mediated DNA methylation is closely related with cancer and bacterial diseases. Herein, a novel strategy based on the keypad lock of duplex DNA modified meso-SiO 2 @Fe 3 O 4 was developed for colorimetric assay of Dam MTase activity. When the Dam MTase was introduced, the duplex DNA can be methylated at a palindrome sequence of 5′-GATC-3′ and cleaved by the methylation-sensitive restriction endonuclease Dpn I. Due to the instability of the newly formed DNA fragment, the hybrid will separated into a single-stranded DNA. Then the keypad lock will open, and the catalytic reaction of TMB and H 2 O 2 can be initiated through the pores of meso-SiO 2 @Fe 3 O 4 , and a high color signal can be clearly observed by the naked eye. Contrarily, without Dam MTase, the catalytic reaction will not be initiated, and result no color signal. The proposed method exhibited a wide dynamic range with a low detection limit of 0.73 U/mL. Additionally, this way can be performed in human serum with satisfying recovery. And the inhibition of Dam MTase can also be well demonstrated by using paclitaxel as a model. Therefore, the designed way not only provides a platform for monitoring Dam MTase activity, but also useful for further application in disease diagnosis and drug discovery.
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JOURNAL OF RARE EARTHS
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2017
·
IF 2.429
Hong DING,Yanling ZHAO,Qianlin DUAN,Junwen WANG,Kan ZHANG,Guangyue DING,Xianmei XIE,Chuanmin DING
Fe 3 O 4 @SiO 2 magnetic nanoparticles functionalized with mesoporous cerium oxide (Fe 3 O 4 @SiO 2 @ m CeO 2 ) was fabricated as a novel adsorbent to remove phosphate from water. The prepared adsorbent was characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption and vibrating sample magnetometry (VSM), and its phosphate removal performance was investigated through the batch adsorption studies. Characterization results confirmed that mesoporous cerium oxide was successfully assembled on the surface of Fe 3 O 4 @SiO 2 nanoparticles, and the synthesized adsorbent possessed a typical core-shell structure with a BET surface area of 195 m 2 /g, accessible mesopores of 2.6 nm, and the saturation magnetization of 21.11 emu/g. The newly developed adsorbent had an excellent performance in adsorbing phosphate, and its maximum adsorption capacity calculated from the Langmuir model was 64.07 mg/g. The adsorption was fast, and the kinetic data could be best fitted with the pseudo-second-order kinetic model. The phosphate removal decreased with the increase of solution pH (2 to 10), while the higher ionic strength slightly promoted the phosphate adsorption. The presence of Cl − and SO 4 2− could enhance the adsorption of phosphate whereas HCO 3 − had interfering effect on the phosphate adsorption. The adsorption mechanism was studied by analyzing Zeta potential and FTIR spectroscopy, and the results indicated that the replacement of the surface hydroxyl groups by phosphate ions with the formation of inner-sphere complex played a key role in the phosphate adsorption. The spent adsorbent could be quickly separated from aqueous solution with the assistance of the external magnetic field, and the adsorbed phosphate could be effectively desorbed using a 1 mol/L NaOH solution.
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SENSORS AND ACTUATORS B-CHEMICAL
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2017
·
IF 5.401
Keqin Deng,Xinyan Liu,Chunxiang Li,Zhaohui Hou,Haowen Huang
Three types of shortened and acidified multi-walled carbon nanotubes (S-MWCNTs) were synthesized by ultrasonication of the raw long carbon nanotubes in H 2 SO 4 /HNO 3 mixed acids. A comparative electrochemical investigation was performed in 5 μM omeprazole (OMZ) solution. It demonstrated that S-MWCNTs with specific length and acidity showed higher electrocatalysis to the oxidation of OMZ. Magnetite nanoparticles Fe 3 O 4 were hybridized with S-MWCNTs to form a nanohybrid (S-MWCNTs-Fe 3 O 4 ) through a simple, effective and reproducible chemical co-precipitation method. The nanohybrid was characterized by transmission electron microscope (TEM), X-ray diffractometer (XRD), thermogravimetric analyses (TGA), and field emission scanning electron microscopy (FESEM). The electrochemical response characteristic of S-MWCNTs-Fe 3 O 4 modified GCE toward OMZ was investigated by cyclic voltammetry. It showed that the nanohybrid enhanced the electrocatalytic oxidation to OMZ. Linear sweep voltametry (LSV) was applied to determine low concentrations of OMZ on S-MWCNTs-Fe 3 O 4 /poly (2,6-pyridinedicarboxylic acid) modified electrode. A linear relationship was found between peak currents ( i p,a ) and the concentration of OMZ within 0.05–9.0 μM with an estimated detection limit of 15 nM.
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ADVANCED POWDER TECHNOLOGY
·
2016
·
IF 2.478
Bin Chen,Shenwen Fang,Ting Chen,Yan Xiong,Ming Duan
Compound poly(methylmethacrylate (MMA)-acrylic acid (AA)-ethyl acrylate (EA))/Fe 3 O 4 superparamagnetic nanoparticles were synthesized successfully by emulsion polymerization and solvothermal reaction methods. The nanoparticles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD) and thermogravimetry analysis (TGA). P(MMA-AA-EA)/Fe 3 O 4 nanoparticles exhibited superparamagnetic properties with a saturation magnetization value of 20 emu/g. The selective adsorption behaviors of nanoparticles toward dyes were investigated and the function of electronic interaction during the adsorption process was also discussed.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2016
·
IF 3.205
Nan Mei,Bing Liu
Catalytic reduction of nitro compounds to the amines is of high importance in modern synthetic chemistry . In this study, an efficient method was developed for the transfer hydrogenation of nitro compounds over a magnetic Pd catalyst by the use of NaBH 4 as the hydrogen donor . Full nitrobenzene conversion and high selectivity (>99%) of aniline were produced after 1 h at 60 °C in ethanol. The reductions are successfully carried out in presence of a wide variety of other reducible functional groups in the molecule, except halogen and vinyl substitute nitrobenzene. Kinetic studies indicated the active energy for the transfer hydrogenation of nitrobenzene was 20.93 KJ mol −1 . The transfer hydrogenation of nitrobenzene was confirmed to proceed via azobenzene as the intermediate. More importantly, the catalyst was very stable without the loss of its catalytic activity .
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2016
·
IF 3.014
Mingtao Qiao,Xingfeng Lei,Yong Ma,Lidong Tian,Wenbin Wang,Kehe Su,Qiuyu Zhang
Functional composite microspheres with porous Fe 3 O 4 cores and hierarchical MnO 2 shells have been synthesized successfully via a two-step hydrothermal method . X-ray diffraction was employed to determine the crystal forms of samples. The morphologies and microstructures of Fe 3 O 4 nanoparticles and Fe 3 O 4 @MnO 2 composite microspheres were observed by the scanning electron microscope and transmission electron microscope. It can be seen that hierarchically structured MnO 2 shells have coated Fe 3 O 4 nanoparticles, and the shell thickness is about 140–160 nm. The BET specific surface area and porosity were estimated by the N 2 absorption-desorption isotherms and the magnetic properties were measured by the vibrating sample magnetometer . As-synthesized Fe 3 O 4 @MnO 2 composite microspheres have a BET specific surface area of 167 m 2 /g, and the pore width is mainly distributed in the mesoporous range, especially from 2.0 nm to 12.0 nm. Investigations of microwave absorbing properties manifest that Fe 3 O 4 @MnO 2 composite microspheres with loading 10% weight fraction possess the strongest RL peak of −42.6 dB (5.7 GHz) at the matching thickness 4.0 mm, and Fe 3 O 4 @MnO 2 composite microspheres with loading 20% weight fraction have a broader absorbing bandwidth (10.2–15.0 GHz and 15.5–17.3 GHz) at the matching thickness 1.5 mm. Achieving the advantages of intensive absorption, wide effective absorbing bandwidth band and intrinsic lightweight feature, porous core-shell Fe 3 O 4 @MnO 2 composite microspheres are believed to be more promising in the application of microwave absorption.
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BIOPROCESS AND BIOSYSTEMS ENGINEERING
·
2017
·Vol. 40
·期 6
·821-831
·
IF 1.87
Long Jie,Li Xingfei,Zhan Xiaobei,Xu Xueming,Tian Yaoqi,Xie Zhengjun,Jin Zhengyu
Abstract Pullulanase was sol–gel encapsulated in the presence of magnetic chitosan/Fe 3 O 4 nanoparticles. The resulting immobilized pullulanase was characterized by scanning electron microscopy, vibrating sample magnetometry, Fourier transform infrared spectroscopy and thermogravimetric analysis. The results showed that the addition of pullulanase created a more regular surface on the sol–gel matrix and an enhanced magnetic response to an applied magnetic field. The maximal activity retention (83.9%) and specific activity (291.7 U/mg) of the immobilized pullulanase were observed under optimized conditions including an octyltriethoxysilane:tetraethoxysilane (OTES:TEOS) ratio of 1:2 and enzyme concentration of 0.484 mg/mL sol. The immobilized enzyme exhibited good thermal stability. When the temperature was above 60 °C, the immobilized pullulanase showed significantly higher activity than the free enzyme ( p < 0.01); enzyme immobilized by simple sol–gel encapsulation and co-immobilized by crosslinking-encapsulation retained 52 and 69% of their initial activity after 5 h at 62 °C, respectively, compared to 11% for the free enzyme. Moreover, the stability of the pullulanase was improved by crosslinking-encapsulation, as the enzyme retained more than 85 and 81% of its original activity after 5 and 6 consecutive reuses, respectively, compared to 80 and 72% of its original activity for simple sol–gel encapsulated enzymes. This indicated the leakage of enzyme molecules through the pores of the gel was substantially abated by cross-linking. Such immobilized pullulanase provides high stability and ease of enzyme recovery, characteristics that are advantageous for applications in the food industry that involve continuous starch processing. Graphical abstract
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ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Yan Zhang,Mingming Gao,Shu-Guang Wang,Weizhi Zhou,Yuanhua Sang,Xin-Hua Wang
In this study, we developed an electro-Fenton (EF) system with a Fe 3 O 4 /gas diffusion electrode (Fe 3 O 4 /GDE) as the rotating cathode, realizing the simultaneous processes of O 2 diffusion, H 2 O 2 generation and activation at the cathode for the first time. In this system, H 2 O 2 was effectively electro-generated on the rotating cathode without external aeration, and then in suit activated to hydroxyl radical by the immobilized Fe 3 O 4 . Experimental results showed that 50 mg L −1 of tetracycline was completely degraded in 120 min, with the total organic carbon removal efficiency of 56.7%, which was accelerated by 1.7 times compared with the mobilized Fe 3 O 4 as catalyst. This enhancement was ascribed to the increased catalytic ability of immobilized Fe 3 O 4 in the presence of electric field. The effects of some important parameters such as Fe 3 O 4 loading, initial pH, applied potential and the rotation speed were evaluated. Computational fluid dynamics simulation suggested that the rotating disk mode greatly enhanced the mass transfer. Further investigation indicated that the immobilized Fe 3 O 4 contributed to the decomposition of H 2 O 2 predominately, while the effects of leaching iron could be ignored. The hydroxyl radical was considered as the primary reactive oxidants, and the degradation mechanism of tetracycline was proposed combined with the analysis of intermediates by ion chromatograph technology. These findings demonstrated the feasibility of establishing an efficient EF system with a simple and cost-effective integrated cathode based on iron immobilization and rotating GDE for environmental remediation.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2017
·
IF 2.714
Yun-Xia Wang,Kiran Gupta,Jian-Rong Li,Baoling Yuan,Jia-Cheng E. Yang,Ming-Lai Fu
A novel easily separated magnetic chalcogenide composite, KMS-1/L-Cystein/Fe 3 O 4 (KCF), was successfully synthesized using bifunctional linker (L-Cystein) to connect KMS-1 and Fe 3 O 4 nanoparticles, and was examined to remove ciprofloxacin (CIP) from aqueous solution. The composite was thoroughly characterized by XRD, SEM, EDX, FTIR and magnetization measurements techniques. The adsorption experiments were carried out and investigated under different conditions, such as contact time and pH of solution. The CIP removal reaction was found to better follow a pseudo-second-order kinetic model than the pseudo-first-order. The Langmuir adsorption isotherm was employed to understand the removal process. The pH of solution is critical for the adsorption of CIP on KCF, and the maximum adsorption (181.32 mg/g) of CIP could be reached under pH 6. In addition, the KCF adsorbent showed magnetization and operational stability, and it could be readily separated from solution by applying an external magnetic field. The high stability, performance, inexpensive, and easily recyclable KCF composite may serve as a promising adsorbent for water treatment.
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DALTON TRANSACTIONS
·
2016
·Vol. 45
·期 34
·13456-13465
·
IF 4.177
Zhifang Gao,Xijian Liu,Guoying Deng,Feng Zhou,Lijuan Zhang,Qian Wang,Jie Lu
In this work, a new multifunctional nanoplatform (Fe3O4@mSiO2-FA-CuS-PEG nanocomposite) for magnetic resonance imaging (MRI) and targeted chemo-photothermal therapy, was firstly fabricated on the basis of magnetic mesoporous silica nanoparticles (Fe3O4@mSiO2), on which folic acid (FA) was grafted as the targeting reagent, CuS nanocrystals were attached as the photothermal agent, and polyethylene glycol (PEG) was coupled to improve biocompatibility. The characterization results demonstrated that the fabricated Fe3O4@mSiO2-FA-CuS-PEG nanocomposites not only showed strong magnetism and excellent MRI performance, but also had a high doxorubicin (DOX, an anticancer drug) loading capacity (22.1%). The loaded DOX can be sustainably released, which was apt to be controlled by pH adjustment and near infrared (NIR) laser irradiation. More importantly, targeted delivery of the DOX-loaded Fe3O4@mSiO2-FA-CuS-PEG nanocomposites could be accomplished in HeLa cells via the receptor-mediated endocytosis pathway, and this exhibited synergistic effect of chemotherapy and photothermal therapy against HeLa cells under irradiation with a 915 nm laser. Therefore, the fabricated multifunctional Fe3O4@mSiO2-FA-CuS-PEG nanocomposite has a great potential in image-guided therapy of cancers.
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