ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2013
·
IF 5.257
Zhihui Ai,Zhiting Gao,Lizhi Zhang,Weiwei He,Jun Jie Yin
In this study, core–shell Fe@Fe2O3 nanowires with different iron oxide shell thickness were synthesized through tuning water-aging time after the reduction of ferric ions with sodium borohydride without any stirring. We found that these Fe@Fe2O3 nanowires exhibited interesting core–shell structure dependent reactivity on the aerobic degradation of 4-chlorophenol. Characterization results revealed that the core–shell structure dependent aerobic oxidative reactivity of Fe@Fe2O3 nanowires was arisen from the combined effects of incrassated iron oxide shell and more surface bound ferrous ions on amorphous iron oxide shell formed during the water-aging process. The incrassated iron oxide shell would gradually block the outward electron transfer from iron core for the subsequent two-electron molecular oxygen activation, but more surface bound ferrous ions on iron oxide shell with prolonging aging time could favor the single-electron molecular oxygen activation, which was confirmed by electron spin resonance spectroscopy with spin trap technique. The mineralization of 4-chlorophenol was monitored by total organic carbon measurement and the oxidative degradation intermediates were analyzed by gas chromatography–mass spectrometry. This study provides new physical insight on the molecular oxygen activation mechanism of nanoscale zerovalent iron and its application on aerobic pollutant removal.
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Journal of Materials Chemistry C
·
2015
·Vol. 3
·期 39
·10232-10241
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IF 4.696
Hualiang Lv,Guangbin Ji,Wei Liu,Haiqian Zhang,Youwei Du
Hierarchical hollow carbon@Fe@Fe3O4 nanospheres were synthesized by a simple template method and another pyrolysis process. Interestingly, the thickness of hollow carbon spheres is tunable by a simple hydrothermal approach. The as-prepared carbon@Fe@Fe3O4 shows excellent microwave absorption properties. In detail, the maximum effective frequency is up to 5.2 GHz with an optimal reflection loss value of −40 dB while the coating thickness is just 1.5 mm. Meanwhile, such absorption properties can be maintained via controlling the thickness of the hollow carbon. For instance, in another coating layer of 2 mm, the effective frequency is still more than 5 GHz as the carbon thickness declines to 12 nm. As novel electromagnetic absorbers, the composites also present the lower density feature due to the hollow carbon sphere frame. The excellent electromagnetic absorption mechanism may be attributed to the obvious interface polarization, and strong magnetic loss ability resulting from the Fe and Fe3O4 shell. Besides, owing to the dielectric feature of carbon, the hollow carbon core is beneficial for the attenuation ability.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2014
·
IF 6.007
Qi Huang,Menghua Cao,Zhihui Ai,Lizhi Zhang
In this study, an environmentally benign polyaminocarboxylic ligand diethylenetriamine pentacetate (DTPA) was first used to promote the aerobic 4-chlorophenol (4-CP) degradation with Fe@Fe 2 O 3 core–shell nanowires, and then compared with the most used counterpart ethylenediamine tetraacetate (EDTA) of poor biodegradability. Although the 4-CP removal rate in the Fe@Fe 2 O 3 /DTPA/Air system was slower owing to the preferential degradation of DTPA, the total organic carbon removal rate in the Fe@Fe 2 O 3 /DTPA/4-CP/Air system was much faster than that in the Fe@Fe 2 O 3 /EDTA/4-CP/Air system. We interestingly found that hydroxyl radicals could more easily react with DTPA to produce DTPA radicals than with EDTA to produce EDTA radicals. Ligands (DTPA or EDTA) could significantly accelerate the hydroxyl radicals production with Fe@Fe 2 O 3 , while more hydroxyl radicals were generated in the Fe@Fe 2 O 3 /DTPA/Air system. We also employed gas chromatography-mass spectrometry and ion chromatography to detect organic intermediates and chloride ions to probe the 4-chlorophenol degradation pathways, and found its degradation pathways were dependent on the reactive oxygen species generated in the different systems. This study can clarify the roles of polyaminocarboxylic ligands on the molecular oxygen activation with nanoscale zero-valent iron, and also provide a green chlorophenols removal method.
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CATALYSIS COMMUNICATIONS
·
2017
·
IF 3.33
Bo Xu,Zhiming Chen,Bing Han,Cuncheng Li
This work presents MIL-100(Fe) nanoparticles synthesized using glycol with uniform size and morphology. This is the first report of nanoscale MOFs material synthesized using glycol. The MIL-100(Fe) particles have been characterized by SEM, TEM, XRD and the results indicate that the MOFs particles show monodispersed nanospherical morphology. Photocatalytic study reveals that the MIL-100(Fe) nanospheres exhibit good oxidation ability of benzene to phenol under visible light irradiation with high selectivity.
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APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Junxia Guo,Qijian Niu,Yichun Yuan,Inamullh Maitlo,Jun Nie,Guiping Ma
One-dimensional (1D) nanomaterials have gained attention in energy conversion, storage, and catalyst due to the unique physical and chemical properties. Electrospinning is a kind of simple, versatile, and cost-effective technology to fabricate 1D functional nanofibers. Herein, electrospun polyacrylonitrile (PAN), melamine, and ferric chloride hexahydrate (FeCl 3 ·6H 2 O) composite nanofibers are used as template, and polythiophene (PT) are prepared by photopolymerization technology on the surface of electrospun nanofibers as shell part of fibers. Then, the core–shell nanofibers are pyrolyzed and converted into Fe–S/N–C nanofibers, which can be used as catalysts for ORR due to the metal and S-/N-codoped structure and unique 1D structure which provided facile pathways for efficient mass transport and charge transfer. The ORR electrocatalytic ability of Fe–S/N–C nanofibers is tested and present excellent property, especially in stability and methanol crossover. The electrocatalytic ability of sample is comparable to that of 20 wt% Pt/C benchmarks. These results offer an easy pathway for exploring metal-heteroatom-codoped carbon nanofibers applicable for ORR catalyst.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 24
·期 31
·24318-24326
·
IF 2.741
Fu Xiaori,Brusseau Mark L.,Zang Xueke,Lu Shuguang,Zhang Xiang,Farooq Usman,Qiu Zhaofu,Sui Qian
This work demonstrates the impact of hydroxylamine hydrochloride (HAH) addition on enhancing the degradation of trichloroethene (TCE) by the citric acid (CA)-chelated Fe(II)-catalyzed percarbonate (SPC) system. The results of a series of batch-reactor experiments show that TCE removal with HAH addition was increased from approximately 57 to 79% for a CA concentration of 0.1 mM and from 89 to 99.6% for a 0.5 mM concentration. Free-radical probe tests elucidated the existence of hydroxyl radical (HO • ) and superoxide anion radical (O 2
•- ) in both CA/Fe(II)/SPC and HAH/CA/Fe(II)/SPC systems. However, higher removal rates of radical probe compounds were observed in the HAH/CA/Fe(II)/SPC system, indicating that HAH addition enhanced the generation of both free radicals. In addition, increased contribution of O 2
•- in the HAH/CA/Fe(II)/SPC system compared to the CA/Fe(II)/SPC system was verified by free-radical scavengers tests. Complete TCE dechlorination was confirmed based on the total mass balance of the released Cl − species. Lower concentrations of formic acid were produced in the later stages of the reaction for the HAH/CA/Fe(II)/SPC system, suggesting that HAH addition favors complete TCE mineralization. Studies of the impact of selected groundwater matrix constituents indicate that TCE removal in the HAH/CA/Fe(II)/SPC system is slightly affected by initial solution pH, with higher removal rates under acidic and near neutral conditions. Although HCO 3
− was observed to have an adverse impact on TCE removal for the HAH/CA/Fe(II)/SPC system, the addition of HAH reduced its inhibitory effect compared to the CA/Fe(II)/SPC system. Finally, TCE removal in actual groundwater was much significant with the addition of HAH to the CA/Fe(II)/SPC system. The study results indicate that HAH amendment has potential to enhance effective remediation of TCE-contaminated groundwater.
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Scientific Reports
·
2017
·Vol. 7
·期 1
·1-11
·
IF 4.259
Laipan Minwang,Fu Haoyang,Zhu Runliang,Sun Luyi,Zhu Jianxi,He Hongping
Recycling solid waste as functional materials is important for both environmental remediation and resource recycling. This study attempts to recycle spent Cu/Fe layered double hydroxide (Cu/Fe-LDH) which is generated from the adsorption of dyes by converting to Cr(VI) reductant and porous carbon material. Results showed that the obtained reductant was mainly composed of Fe 0 and Cu 0 , and exhibited good reductive activity toward Cr(VI). The species of Fe 0 , Fe 2+ , Cu 0 , and Cu + all favored the reduction of Cr(VI) according to X-ray photoelectron spectroscopy analysis. During Cr(VI) removal, solution pH could increase to neutral which caused the metal ions to precipitate near completion. On the other hand, the spent Cu/Fe-LDH could be employed to produce porous carbon materials, and the generated waste metals solution herein could be reused for LDH synthesis. Specific surface areas of the obtained carbon materials varied from 141.3–744.2 m 2 /g with changes in adsorbed amount of dyes on the LDH. This study illustrates that all the components of wastes can be useful resources, offering a simple recycling approach for similar organic-inorganic solid wastes. This work also enlightens us that designing a proper initial product is crucial to make waste recycling simpler.
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Journal of Materials Chemistry C
·
2016
·Vol. 4
·期 32
·7614-7621
·
IF 5.066
Junyao Shen,Yongtao Yao,Yanju Liu,Jinsong Leng
We demonstrate a facile, template-free route for Fe nanowires (NWs) with an average diameter of 100 nm through magnetic-field-assisted hydrothermal conditions. The aspect ratio of the Fe NWs reaches 50. Fe NWs are constructed with interconnected bead-like nanospheres, which are composed of primary nanocrystals (NCs) with an average size of 8 nm. This shows that the polycrystalline Fe NWs have a body-centred cubic (bcc) structure with preferential growth on the 〈110〉 zone axis. Such hierarchical structures involve orientational growth in the presence of an external magnetic field. The molarity of the reducing agent, reaction time and temperature, are further investigated to understand the influence of these parameters on the growth process of Fe NWs. Compared with those of Fe nanoparticles (NPs), the magnetic properties of Fe NWs show both higher saturation magnetization (154.03 emu g−1) and coercivity (360.84 Oe). The peak value of reflection loss (RL) reaches up to −27.28 dB at 3.68 GHz, indicating the excellent microwave absorption performance of the Fe NWs for low gigahertz usage (2–6 GHz). This mild approach to control Fe NWs is easy to scale-up for other iron-related magnetic nanodevice applications.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Zhiwang Yang,Xueqing Xu,Xixi Liang,Cheng Lei,Yuli Wei,Peiqi He,Bolin Lv,Hengchang Ma,Ziqiang Lei
A series of MIL-53(Fe)-graphene nanocomposite photocatalysts were synthesized by a facile one-pot solvothermal reaction. All materials have been thoroughly characterized by FT-IR, SEM, TEM, PXRD, UV–vis DRS and PL analysis. It was demonstrated that the introducing of graphene on the MIL-53(Fe) would minimize the recombination of photogenerated electron-hole pairs, thus, leading to the enhancement of photocatalytic activity. MIL-53(Fe)-graphene nanocomposite was an efficient catalyst towards the photocatalytic selectively oxidation of alcohols to the corresponding aldehydes or ketones under visible light and ambient conditions. High selectivity of the aldehydes or ketones (99%) were obtained. Meanwhile, the catalyst can be recycled at least four times without loss of catalytic efficiency. A possible photocatalytic reaction mechanism involving a direct photogenerated hole-oxidation process was also investigated in detail by the active species trapping experiments and the related electrochemical analysis.
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CHEMOSPHERE
·
2017
·
IF 4.208
Zilong Zhao,Wenyi Dong,Hongjie Wang,Guanhan Chen,Wei Wang,Zekun Liu,Yaguang Gao,Beili Zhou
Elimination of hypophosphite (HP) was studied as an example of nickel plating effluents treatment by O 3 /H 2 O 2 and sequential Fe(II) catalytic oxidation process. Performance assessment performed with artificial HP solution by varying initial pH and employing various oxidation processes clearly showed that the O 3 /H 2 O 2 ─Fe(II) two-step oxidation process possessed the highest removal efficiency when operating under the same conditions. The effects of O 3 dosing, H 2 O 2 concentration, Fe(II) addition and Fe(II) feeding time on the removal efficiency of HP were further evaluated in terms of apparent kinetic rate constant. Under improved conditions (initial HP concentration of 50 mg L −1 , 75 mg L −1 O 3 , 1 mL L −1 H 2 O 2 , 150 mg L −1 Fe(II) and pH 7.0), standard discharge (<0.5 mg L −1 in China) could be achieved, and the Fe(II) feeding time was found to be the limiting factor for the evolution of apparent kinetic rate constant in the second stage. Characterization studies showed that neutralization process after oxidation treatment favored the improvement of phosphorus removal due to the formation of more metal hydroxides. Moreover, as a comparison with lab-scale Fenton approach, the O 3 /H 2 O 2 ─Fe(II) oxidation process had more competitive advantages with respect to applicable pH range, removal efficiency, sludge production as well as economic costs.
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ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Jia Liu,Jinshuo Qiao,Hong Yuan,Jie Feng,Chao Sui,Zhenhua Wang,Wang Sun,Kening Sun
Ni modified Ce 0.6 Mn 0.3 Fe 0.1 O 2 (Ni-CMF) material is evaluated as an anode material for hybrid direct carbon fuel cell (HDCFC). The Temperature Programmed Reaction (TPR) and GC test results show that the Ni additive significantly promotes the oxidation of carbon and consequently accelerates the formation rate of CO. Moreover, the Ni-CMF material is found to show a high electrical conductivity compared to pure CMF in HDCFC operating conditions. Taking advantage of the excellent catalytic activity and high conductivity, the electrolyte-supported HDCFC with Ni-CMF anode shows a high maximum power density of 580.7 mW cm −2 at 800 °C, when activated carbon is used as the fuel. Furthermore, the cell displays good stability under galvanostatic operation at current density of 50 mA cm −2 at 750 °C. These results indicate that the designed Ni-CMF composite material has the potential to be developed as an alternative anode for HDCFCs.
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Scientific Reports
·
2017
·Vol. 7
·期 1
·1-11
·
IF 4.259
Liu Renlan,Zhu Xiaoying,Chen Baoliang
Graphene oxide (GO) contains not only aromatic carbon lattice but also carboxyl groups which enhanced the aqueous solubility of GO. To study the transformation of GO nanosheets in natural environments, GO aqueous dispersion was mixed with Fe 3+ ions to form photoactive complex. Under visible light irradiation, Fe(III) of the complex would be reduced to Fe(II) which could subsequently reduce highly toxic Cr(VI) to Cr 3+ . The electron of the reduction was contributed by the decarboxylation of carboxyl groups on GO and iron was acting as a catalyst during the photoreduction. On the other hand, the consumption of carboxyl groups may convert GO to rGO which are tend to aggregate since the decreased electrostatic repulsion and the increased π-π attraction. The formed Cr 3+ may be electrostatically adsorbed by the rGO sheets and simultaneously precipitated with the aggregated rGO sheets, resulting the effective removal of chromium and GO nanosheets from the aqueous environment. This study may shed a light on understanding the environmental transformation of GO and guide the treatment of Cr(VI).
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