JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2018
·
IF 2.196
Yihong Jiang,Weiquan Cai,Wenjun Tu,Mengyuan Zhu
The magnetic Fe3O4@SiO2–chitosan (MFSC) with an extremely high adsorption capacity of 336.7 mg g–1 toward toxic Cr(VI) was synthesized successfully by a simple cross-link method. The physicochemical properties of the Fe3O4, Fe3O4@SiO2, and MFSC were characterized comparatively via X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, N2 adsorption–desorption, X-ray photoelectron spectroscopy analysis, and vibrating sample magnetometer. Their adsorption processes are well-fitted by the pseudo-second-order kinetic model; their equilibrium isotherms are better matched with the Langmuir isotherm. Further recycling experiments of MFSC show that its adsorption capacity of 78.6 mg g–1 still remains 81.7% of the original value (96.2 mg g–1), even after five times reuse. The interference adsorption experiments show that MFSC has stronger affinity for Cr(VI) in the solution containing Cr(VI), Cd(II), Cu(II), Zn(II), and Ni(II). The high adsorption capacity, good selectivity, and easy separation of MFSC clearly indicate that it is a potential recyclable adsorbent for Cr(VI) removal from wastewater.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2018
·
IF 3.909
Hongbo Suo,Lili Xu,Chao Xu,Hongyue Chen,Dinghua Yu,Zhen Gao,He Huang,Yi Hu
Magnetic chitosan nanocomposites were designed and fabricated by combining the magnetic nanoparticles Fe 3 O 4 and chitosan covalently modified by imidazole-based ionic liquids with various functional groups, to be utilized as a support matrix for immobilization of porcine pancreatic lipase (PPL). Ionic liquids modified chitosan was characterized with nuclear magnetic resonance (NMR) and the nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), vibrating-sample magnetometer (VSM), thermogravimetry analysis (TGA), Transmission electron microscope (TEM) and Scanning electron microscopy (SEM). The enzymatic properties of PPL were significantly improved by immobilization onto all thus prepared nanocomposites, and among the supports, modified with ionic liquids bearing hydroxyl group exhibited relatively enhanced performance. Particularly, the MCS-IL(8C)-OH-PPL exhibited the highest specific activity which was 6.68 times that of free PPL, and the residual activity of MCS-IL(8C)-OH-PPL remarkably maintained 91.5% of its initial activity even after 10 repeated cycles. The residual activity of MCS-IL(8C)-OH-PPL retained 55.8% after incubated in 6 M urea solution for 1 h and maintained the noticeable initial activity of 75.5% after incubated in phosphate buffer at 50 °C with pH 7.5 for 6 h. In conclusion, the study demonstrated that Fe 3 O 4 @Chitosan nanocomposites modified with functional ionic liquids could be utilized as a novel nanosupport for enzyme immobilization .
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ANALYTICAL CHEMISTRY
·
2018
·
IF 6.042
Na Li,Ting Zhong,Jia-liang Liu,Jun Zheng,Hu-cheng Deng,Wen Zhou,Ming Li,Ming-shi Feng,Qi-jun Liu,Chong-ying Li
Analysis and characterization of micro/nano-sized pore structure are critical issues in shale geology and engineering. Scanning electron microscopy (SEM) imaging is one of the most widespread methods for the analysis of the micro/nano-sized pores in shale, but precise identification of the ultrafine pore structure in shale is still a big challenge because shale is so complex that some components may have overlap with pores based on the simple discrimination of gray scale under SEM microscopy. Here, Fe3O4/Au nanocomposite with magnetic properties is synthesized, characterized, and introduced as a novel pore-marker to improve SEM identification and quantitation of micro/nano-sized pores in shale. Due to the superparamagnetic property, the nanomarker is conveniently controlled by an external magnetic field to fill into pores and offers a sharp contrast imaging between matrix of shale (various gray) and pores (bright), which makes the identification of micro/nano-sized pores in shale much more straightforward and reliable. Furthermore, because gold, as a noble metal, is particularly rare in shale, energy-dispersive X-ray spectroscopy mapping of Au is delicately used to precisely calculate area porosity in shale. Combining with the aforementioned merits of the nanomarker, a precise and practical technique is proposed to promote characterization of micro/nano-sized pores in shale.
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Nanomaterials
·
2018
·Vol. 8
·期 7
·537
·
IF 3.504
Haijiao Lu,Jingkang Wang,Fei Li,Xin Huang,Beiqian Tian,Hongxun Hao
Recyclable nanomaterials are in great need to develop clean technology for applications in the removal of water contaminants. In this work, easily separable montmorillonite/Fe3O4/humic acid (MFH) nanocomposites were fabricated through a facile hydrothermal route. It was found the adsorption ability and stability of MFH was significantly enhanced due to the synergistic effects between montmorillonite, Fe3O4nanoparticles and humic acid. The MFH nanocomposites are highly efficient and recyclable as they can remove at least 82.3% of Cr(VI) and 95.1% of aniline in six consecutive runs. The adsorption mechanism was investigated by analyzing the kinetic parameters of pseudo first-order, pseudo second-order, and intraparticle diffusion models and describing the equilibrium isotherms of Langmuir and Freundlich models. Results indicated different adsorption mechanisms of Cr(VI) and aniline by MFH. The readily synthesized MFH nanocomposites can act as effective and practical materials for environmental applications.Keywords:nanocomposites;wastewater;adsorption;kinetics;isotherms;reusability
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KOREAN JOURNAL OF CHEMICAL ENGINEERING
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2019
·Vol. 36
·期 5
·729-739
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IF 2.476
Pan Jiaying,Ou Zhimin,Tang Lan,Shi Hanbing
Racemic 1-phenylethylamine was resolved by enantiomer selective acetylation using Fe 3 O 4 -chitosan microsphere (CTS)-glutaraldehyde-lipase in a solvent-free system under an alternating magnetic field. Magnetic chitosan microspheres (Fe 3 O 4 -CTS) were prepared via chemical co-precipitation and cross-linked with lipase using glutaraldehyde to form Fe 3 O 4 -CTS-glutaraldehyde-lipase particles. The magnetic, physicochemical, and textural characteristics of Fe 3 O 4 -CTS-glutaraldehyde-lipase particles were assessed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The optimal immobilization conditions were 2.4 mg/mL lipase, 10 mg/mL Fe 3 O 4 -CTS-glutaraldehyde, pH 8.5, 35 °C, 3 h. The loading amount of lipase and the specific activity got to 132 mg/g carrier and 48 U/g. The optimal reaction conditions of the acylation reaction using Fe 3 O 4 -CTS-glutaraldehyde-lipase were 300 mmol/L 1-phenylethylamine, 150 mg immobilized lipase, 2 mL vinyl acetate, 12.6 ×g rotating speed, 40 °C, 8 h. The activity of the Fe 3 O 4 -CTS-glutaraldehyde-lipase particles and conversion were improved when they were exposed to an external alternating magnetic field. The optimum magnetic field was 12 Gs (500 Hz). The conversion, enantiomeric excess of ( R )- N -(1-phenylethyl)acetamide, and E value reached 41.8%, 98.4%, and 264, respectively. Fe 3 O 4 -CTS-glutaraldehyde-lipase could be reused seven times. A kinetic model of the immobilized lipase-catalyzed resolution of 1-phenylethylamine was set up based on the ping-pong bi-bi mechanism. The kinetic constants were V max =1.62×10 −2 mM/min, K A =2.84×10 −4 mM, and K B =5.8×10 −1 mM. The model data fit well with the experimental data.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2018
·Vol. 411
·期 2
·507-515
·
IF 3.307
Yang Yi,Yin Shuo,Yang Danni,Jiang Yang,Li Yongxin,Zhou Chen,Sun Chengjun
A novel carboxyl Fe 3 O 4 magnetic nanoparticle-based solid-phase extraction combined with high-performance liquid chromatography was developed for the analysis of oxytetracycline, tetracycline, demeclocycline, metacycline, chlortetracycline, and doxycycline in water samples. Driven by the electrostatic interaction and the strong chelation between tetracyclines and iron ions, tetracyclines in samples were adsorbed onto the adsorbents. The adsorbed analytes were subsequently eluted with oxalic acid and separated with a C 18 column under gradient condition with a mobile phase consisting of methanol, acetonitrile, and oxalic acid at a flow rate of 0.5 mL/min. The detection was performed at variable ultraviolet wavelengths. Under optimized conditions, the developed method gave an enrichment factor of 33.3, linearity ranges of 5.00–1000 μg/L, detection limits of (2.86–5.19) × 10 -2 μg/L, quantification limits of (9.54–17.3) × 10 -2 μg/L, recoveries of 76.2–98.0%, and intra- and inter-day RSDs of 0.132–15.5% and 2.28–14.5% for these tetracyclines. The established method was successfully applied for the determination of these six tetracyclines in tap water, river water, pond water, and lake water samples.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2018
·
IF 3.909
Haifeng Hu,Liu Yang,Zhen Lin,Xiaotong Xiang,Xiancai Jiang,Linxi Hou
A novel magnetic bioadsorbent beads composed of Fe 3 O 4 , chitosan, and Al(OH) 3 (Fe 3 O 4 /CS/Al(OH) 3 ) was synthesized by a modified solvothermal and in-situ reaction. The composite adsorbent was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and vibrating sample magnetometer, respectively. Adsorption toward F − onto Fe 3 O 4 /CS/Al(OH) 3 was investigated as a function of Fe 3 O 4 concentration, initial solution pH, adsorbent dosage, initial fluorion concentration, co-existing ions in water and initial temperature. The addition of Fe 3 O 4 could enhance the adsorption properties of CS/Al(OH) 3 . The saturated adsorption capacity of magnetic Fe 3 O 4 /CS/Al(OH) 3 calculated from the Langmuir isotherm model was 76.63 mg/g at 298 K. The adsorption isotherm of F − followed Langmuir isotherm model and the adsorption kinetics fitted better to the pseudo-second order kinetic model. The influence of temperature confirmed that the adsorption was spontaneous and endothermic. The magnetic Fe 3 O 4 /CS/Al(OH) 3 beads could be easily separated from water under a low magnetic field.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Jiandong Cui,Sizhu Ren,Tao Lin,Yuxiao Feng,Shiru Jia
Enzyme immobilization on solid supports is a valuable approach to address enzyme stability and reuse for continuous operations. However, the enzymes immobilized on the external surface of solid supports may not be protected by carriers and suffer inactivation caused by denaturing stresses and hazard external environment. Herein, we describe for the first time a enzyme-shielding strategy to prepare hybrid organic/inorganic nanobiocatalysts; it exploits the self-assembly of supramolecular metal-organic coordination complex (tannic acid (TA) and Fe 3+ ) at the surface of immobilized catalase on Fe 3 O 4 /silica core-shell nanospheres to grow a protective nanocoating (Fe 3+ -TA nanocoating). The nanocoatings around the immobilized catalase (Fe 3+ -TA@Fe 3 O 4 /SiO 2 -catalase) provide a “shield effect” to protect from biological, thermal and chemical degradation for enzyme. As a result, the stability of immobilized catalase against proteolytic agent, denaturants and heat were improved remarkably compared to the immobilized catalase without a protective nanocoating and free catalase. More importantly, the recycling of the immobilized catalase was improved remarkably. The Fe 3+ -TA@Fe 3 O 4 /SiO 2 -catalase still retained 55% of their original activity after 9 cycles, whereas the immobilized catalase without a protective nanocoating only retained 20% of original activity. These results demonstrated that the novel enzyme-shielding strategy is an efficient method to obtain stable and recycled biocatalyst with yolk-shell structure.
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BIOSENSORS & BIOELECTRONICS
·
2013
·
IF 5.437
Dan Wu,Haixia Fan,Yuyang Li,Yong Zhang,Huixin Liang,Qin Wei
Dumbbell-like Pt–Fe 3 O 4 nanoparticles (NPs) were synthesized and used as a novel kind of label for the preparation of electrochemical immunosensor, which is applied to the detection of cancer biomarker squamous cell carcinoma antigen (SCC-Ag). The signal amplification strategy, using the synergetic effect present in Pt–Fe 3 O 4 to increase the reduction ability of the NPs toward H 2 O 2 , improved the sensitivity of the immunosensor. Nitrogen-doped graphene sheets (N-GS) were synthesized from graphite oxides through thermal annealing of graphite oxides in ammonia, which was used to immobilize primary anti-SCC antibody (Ab 1 ). Secondary anti-SCC antibody (Ab 2 ) was adsorbed onto the Pt–Fe 3 O 4 NPs. The immunosensor was prepared through a sandwich structure and displayed a wide linear range (0.05–18 ng/mL), low detection limit (15.3 pg/mL), good reproducibility and stability. The method has been applied to the analysis of clinical serum samples with satisfactory results. These labels for immunosensors can provide many potential applications for the detection of different biomolecules .
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CHEMICAL ENGINEERING JOURNAL
·
2012
·
IF 3.461
Jianming Zhang,Shangru Zhai,Shi Li,Zuoyi Xiao,Yu Song,Qingda An,Ge Tian
Contamination of natural water with heavy metals (especially lead ions) is a problem of major concern and thus great demand of effective adsorbents for removal of toxic ions is increasing. Due to the task-specific properties of amino groups, core–shell nanostructures of Fe 3 O 4 @SiO 2 –NH 2 have been extensively investigated as advanced adsorbents; however, most studies on surface modification of Fe 3 O 4 @SiO 2 substances were of environmentally inefficient grafting methods. Herein, we demonstrated that mono-dispersed and spherical Fe 3 O 4 @SiO 2 –NH 2 nanomaterials can be facilely prepared by co-condensation of TEOS with APTMS employing a green sol–gel process. The as-prepared Fe 3 O 4 @SiO 2 –NH 2 magnetic nanoparticles (MNPs) prepared under optimum conditions possessing uniform core–shell structure (∼200 nm in diameter), relatively high loading of amino-functionality (∼5.45 wt%), easy recovery by external magnet and effective removal of Pb(II) ( q m = 243.9 mg/g, 25 °C). The adsorption was shown to be effective and a higher temperature was more favorable for the adsorption. The adsorption equilibrium data obeyed the Langmuir model and the kinetic data were well fitted to the pseudo-second-order model. Thermodynamic studies revealed the feasibility and endothermic nature of the system. These results demonstrated that the sol–gel produced Fe 3 O 4 @SiO 2 –NH 2 , due to its easy synthesis and recovery and eco-friendliness, can be a potential adsorbent for Pb(II) removal.
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JOURNAL OF NANOPARTICLE RESEARCH
·
2014
·Vol. 16
·期 11
·1-10
·
IF 2.278
Yao Yang Rong,Huang Wan Zhen,Zhou Huan,Cui Xia,Zheng Yi Fan,Song Xu Chun
A core–shell nanostructured magnetic photocatalyst Fe 3 O 4 @SiO 2 @Ag 3 PO 4 with a grain size ranging from 200 to 400 nm was prepared via a facile and effective method. The as-prepared products were characterized using X-ray diffraction, high-angle annular dark field-scanning transmission electron microscopy, energy-dispersive spectroscopy, and UV–Vis diffuse reflectance spectra. The photocatalytic activity was evaluated by the degradation of 10 −5 M RhB solution under visible light irradiation with a cut-off filter ( λ ≥ 420 nm). The results showed that nearly 100 % color removal efficiency was achieved in 45 min with the presence of Fe 3 O 4 @SiO 2 @Ag 3 PO 4 photocatalyst. Furthermore, it can be easily recollected from the solution by magnetic separation and efficiently recycled without major loss of activity due to its superior magnetic responsibility and extremely high reusability, exhibiting highly potential applications in water purification avoiding the secondary pollution.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2013
·
IF 3.172
Xiaoshu Lv,Xiaoqin Xue,Guangming Jiang,Donglei Wu,Tiantian Sheng,Hongyi Zhou,Xinhua Xu
Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe 3 O 4 /graphene (nZVI@MG) nanocomposites was synthesized for Cr(VI) removal from aqueous solution. nZVI particles were perfectly dispersed either among Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs) or above the basal plane of graphene. This material shows Cr(VI) removal efficiency of 83.8%, much higher than those of individuals (18.0% for nZVI, 21.6% for Fe 3 O 4 NPs and 23.7% for graphene) and even their sum of 63.3%. The removal process obeys pseudo-second-order adsorption model, suggesting that adsorption is rate-controlling step. Maximum Cr(VI) adsorption capacity varies from 66.2 to 101.0 mg g −1 with decreasing pH from 8.0 to 3.0 at 30 °C. Negative Δ G and Δ H indicate spontaneous tendency and exothermic nature. Robust performance of nZVI@MG arises from the formation of micro-nZVI-graphene/nZVI-Fe 3 O 4 batteries and strong adsorption capability of broad graphene sheet/Fe 3 O 4 surfaces. Electrons released by nZVI spread all over the surfaces of graphene and Fe 3 O 4 , and the adsorbed Cr(VI) ions on them capture these floating electrons and reduce to Cr(III). Fe 3 O 4 NPs also served as protection shell to prevent nZVI from agglomeration and passivation.
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