POWDER TECHNOLOGY
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2019
·
IF 3.413
Zhi-Bo Li,Guo-Hua Zhang,Kuo-Chih Chou
The ultrafine composite powders of two different compositions (90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe, wt%) were synthesized by a two-stage reduction process consisting of carbothermic pre-reduction and the following deep reduction by hydrogen, and then the densification behaviors of them were investigated. The prepared W-Ni-Fe composite powders by the new proposed two-stage method had the particle size ranged from 200 nm to 400 nm. The sintered compacts of these two kinds of W-Ni-Fe powders achieved nearly full densification at a sintering temperature of 1400 °C within 3 h. The maximum hardness of the alloys obtained at 1300 °C were 411 HV and 358 HV, and the bending strength of >1500 MPa was achieved at 1400 °C for the compositions of 90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe, respectively. Meanwhile, the bending fracture mechanism was also investigated, which was different for the samples sintered at different temperatures.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2019
·
IF 4.182
Zeyu Han,Feng Zhang,Xinhong Zhao
Currently, there remains a great challenge to synthesize zeolites in an energy-saving and environmentally friendly manner. Herein we report a novel solvent-free route of synthesizing Fe-ZSM-5 zeolite, which is featured by using Fenton's reagent as a promoter. The influences of crystallization time, amount of hydrogen peroxide and low-temperature pretreatment on the synthesis of Fe-ZSM-5 zeolite were investigated in detail. The results indicate that the combination of solvent-free synthesis with Fenton's reagent can facilitate the rapid crystallization of Fe-ZSM-5 zeolite. The resultant Fe-ZSM-5 zeolite was used as a catalyst for phenol hydroxylation, and characterized by XRD , SEM, ICP-AES, N 2 physisorption and UV–Vis diffuse reflectance spectroscopy. Notably, it exhibits a much better catalytic performance as compared with the reference catalyst by conventional solvent-free method. The observed enhanced catalytic performance for this Fe-ZSM-5 catalyst is attributed to its larger BET surface area and mesoporous volume as well as enrichment towards phenol.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2018
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IF 4.61
Pingping Yan,Qian Sui,Shuguang Lyu,Hongyuan Hao,Horst Friedrich Schröder,Wilhelm Gebhardt
Fe(II) activated sodium percarbonate (SPC) process (SPC/Fe(II)) could efficiently remove sulfamethoxazole (SMX) in the aqueous phase, and has the potential in groundwater remediation . However, the degradation mechanisms, especially the degradation products and pathways till now have remained unclear. In the present study, intermediate products were identified using high resolution liquid chromatography coupled with ion trap and time-of-flight mass spectrometry (LCMS-IT-TOF). Nine intermediate products were identified, six of which have not yet been reported during the oxidation of SMX. The oxidation mechanisms involved hydroxyl substitution, the cleavage of sulfonamide bond, isoxazole ring opening and a rearrangement following the loss of the SO 2 -group. Based on the identified intermediate products, the degradation pathways of SMX by SPC/Fe(II) process were illustrated. Fenton's reaction after the dissolution of SPC was proposed as the main reaction mechanisms, which was checked and confirmed by radical species detection tests and radical species scavenging studies. The results showed that although both O 2 − and HO were present in SPC/Fe(II) system, HO was dominant in the system while O 2 − was seldom involved in the degradation of SMX. These findings provided useful information and supported the application of this advanced oxidation process for antibiotics elimination in the groundwater.
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Journal of Environmental Sciences
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2018
·
IF 3.12
Jianqiang Sun,Xiaobing Zhang,Anping Zhang,Chunyang Liao
To obtain a cost-effective adsorbent for the removal of arsenic in water, a novel nanostructured Fe–Co based metal organic framework (MOF-74) adsorbent was successfully prepared via a simple solvothermal method. The adsorption experiments showed that the optimal molar ratio of Fe/Co in the adsorbent was 2:1. The Fe 2 Co 1 MOF-74 was characterized by various techniques and the results showed that the nanoparticle diameter ranged from 60 to 80 nm and the specific surface area was 147.82 m 2 /g. The isotherm and kinetic parameters of arsenic removal on Fe 2 Co 1 MOF-74 were well-fitted by the Langmuir and pseudo-second-order models. The maximum adsorption capacities toward As(III) and As(V) were 266.52 and 292.29 mg/g, respectively. The presence of sulfate, carbonate and humic acid had no obvious effect on arsenic adsorption. However, coexisting phosphate significantly hindered the removal of arsenic, especially at high concentrations (10 mmol/L). Electrostatic interaction and hydroxyl and metal–oxygen groups played important roles in the adsorption of arsenic. Furthermore, the prepared adsorbent had stable adsorption ability after regeneration and when used in a real-water matrix. The excellent adsorption performance of Fe 2 Co 1 MOF-74 material makes it a potentially promising adsorbent for the removal of arsenic.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2018
·
IF 4.61
Jun Hu,Zhiyong Huang,Jianming Yu
In this study, Fe/Fe 3 O 4 mixture was first applied as an additive to achieve the highly-effective mechanochemical destruction (MCD) of two halogenated organic pollutants (HOPs), hexachloroethane (HCE) and hexachlorobenzene (HCB). The MCD of HCE was more effective than that of HCB in virtue of the lower dissociation energy of C Cl bond. The MCD of HOPs occurred mainly via the reduction by Fe, Fe 3 O 4 and Fe/Fe 3 O 4 . The oxidation of Fe 3 O 4 and reduction of FeO (formed on account of the oxidation of Fe by oxygen-containing species) may also contribute to the HOP destruction. Fe/Fe 3 O 4 mixture exhibited a higher dechlorination rate (DR) than other three effective additives (i.e., Fe/SiO 2 , Al/Al 2 O 3 and Mg/Al 2 O 3 mixture), owing to the electrical property of Fe 3 O 4 and its electron transfer with Fe. The HOP destruction was significantly impacted by the mass fraction of Fe 3 O 4 (MF mag ) and achieved the maximum level with an MF mag of 70%. The DR of HOPs in the atmosphere of air was higher than those of pure oxygen and nitrogen because of the oxygen vacancy in Fe 3 O 4 and oxidation of Fe. The presence of water dramatically inhibited the HOP destruction due to the decrease of collision energy and its competition for the active sites in both Fe and Fe 3 O 4 . As expected, the DR of HOPs increased with rotation speed, and the mass ratio of ball to reactant and additive to pollutant. The analysis of intermediates indicates that HCB destruction was mainly via dechlorination and polymerization, while HCl cleavage also played an important role in HCE destruction. The results demonstrate that Fe/Fe 3 O 4 mixture is a suitable additive for MCD process.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
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IF 11.698
Munir Ahmad,Shuo Chen,Fei Ye,Xie Quan,Shahzad Afzal,Hongtao Yu,Xueyang Zhao
Metal-organic frameworks (MOFs) have received significant interest as a promising photocatalyst for environmental remediation due to its high surface area and porous nature. The small pores (<2 nm) in microporous MOFs help the adsorption of small molecules but limits diffusion and accessing of bigger molecules from MOF cavities, thus preventing their applications in some situation. The aim of this work is to fabricate mesoporous MOF composite with larger pore sizes (>2 nm) and open pore cavities that can provide right pathways for ingoing and outgoing of molecules during catalysis. Herein, we successfully report stable mesoporous MIL-100(Fe) loaded with ZnO NS by an in situ self-assembly method. The prepared samples were characterized by Brunauer–Emmett–Teller (BET) and N 2 adsorption-desorption isotherm to study their surface area and porosity. The catalytic performance of mesoporous MIL-100(Fe) was approximately 2–3 order of magnitude more than that of microporous MIL-100(Fe). Such higher catalytic activity in mesoporous MIL-100(Fe) can be ascribed to its mesocellular structure which can improve the molecular diffusion and accessibility inside MOF channels. The charge separation efficiency and photo-Fenton activity of mesoporous MIL-100(Fe) can further be increased by introduction of certain amount of ZnO NS and H 2 O 2 . Moreover, the as synthesized sample shows higher photo-Fenton degradation efficiency at lower pH value with certain amount of H 2 O 2 . Lastly, the possible catalytic mechanism has been tentatively proposed. This study not only used for the pollutants degradation but also provide useful platform for the application of mesoporous MOFs as an efficient photo-Fenton activity to various other fields.
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Nano Energy
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2018
·
IF 13.12
Xuemin Hu,Shengli Zhang,Jingwen Sun,Lei Yu,Xingyue Qian,Rudan Hu,Yining Wang,Hongan Zhao,Junwu Zhu
Two-dimensional (2D) heterostructures have emerged as promising electrocatalysts towards oxygen evolution reaction due to their unique structural and chemical properties. Moreover, 2D lateral heterostructure with the coupled interface in-plane rather than the vertical direction enables to expose more active sites to catalyst surface , and thus facilitates the OER catalytic activity . Here, 2D FeCo layered double hydroxide/cobalt oxide (FeCo LDH/CoO) nanosheets are synthesized via an instantaneous method utilizing molten alkali as both solvent and reactant. Upon a selective low-temperature phosphorization, 2D Fe-containing cobalt phosphide/cobalt oxide (Fe-CoP/CoO) lateral heterostructure with the optimized electronic structure and activated electronic coupling interface is obtained and exhibits superior catalytic activity (η = 219 mV at 10 mA cm −2 ) compared to most of the reported electrocatalysts towards OER in alkaline electrolyte . Besides, both of the experimental characterization and DFT calculation are performed to illustrate the detailed mechanism of the attractive OER activity. It is uncovered that the coupled interface between CoP and CoO induces the redistribution of electrons, facilitates the adsorption of OH - anions easily, and thus optimizes Gibbs free energies for water oxidation .
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ENERGY & FUELS
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2018
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IF 3.024
Chao Cai,Ning Fu,Ziwei Zhou,Mengchen Wu,Zhenglong Yang,Rui Liu
A tannic acid-Fe coordination compound has been prepared via a simple mechanochemical method. The compound could be used as precursors for the fabrication of porous carbon, which was successfully applied as adsorbent for CO2 capture. The obtained porous adsorbent, NFePC-10-A, exhibited relatively high CO2 uptake capacities of 5.8 and 3.4 mmol g–1 at 0 and 25 °C, respectively. In addition, the initial isosteric heat of adsorption and selectivity for CO2/N2 were as high as 63.16 kJ mol–1 and 22.7 (0 °C). Meanwhile, the adsorbent underwent an efficient reusability, indicating a good potential for practical use. This feasible strategy might provide a novel precursor for the large-scale production of bio-derived carbonaceous adsorbents with tailored texture and porosity for CO2 capture and storage.
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JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
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2018
·Vol. 317
·期 3
·1223-1233
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IF 1.181
Liu Zhirong,Yu Jiehao,Yang Lingfang,Dai Ying,Wang Yun,Zhou Liming
Three kinds of method were employed to prepare Fe loaded activated carbon (Fe-AC), liquid reduction method, carbonthermal method, incipient wetness method, respectively. Before and after adsorption, the adsorption property of Fe-AC had been analysed.
Results indicated that the removal mechanisms were mainly redox reaction, adsorption and precipitation. In addition, the adsorption models fitted with the kinetic model and adsorption isotherm model. Based on the analysis of six influencing factors, we obtain some actual information to deal with the humic acid and the “back to acid”.
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ULTRASONICS SONOCHEMISTRY
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2012
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IF 3.567
Deming Zhao,Min Li,Dexing Zhang,Shams Ali Baig,Xinhua Xu
Palladium/Iron (Pd/Fe) nanoparticles were prepared by using ultrasound strengthened liquid phase reductive method to enhance dispersion and avoid agglomeration. The dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd/Fe nanoparticles was investigated to understand its feasibility for an in situ remediation of contaminated groundwater. Results showed that 2,4-DCP was first adsorbed by Pd/Fe nanoparticles, then quickly reduced to o-chlorophenol (o-CP), p-chlorophenol (p-CP), and finally to phenol (P). The induction of ultrasound during the preparation of Pd/Fe nanoparticles further enhanced the removal efficiency of 2,4-DCP, as a result, the phenol production rates increased from 65% (in the absence of ultrasonic irradiation) to 91% (in the presence of ultrasonic irradiation) within 2 h. Our data suggested that the dechlorination rate was dependent on various factors including Pd loading percentage over Fe 0 , Pd/Fe nanoparticles availability, temperature, mechanical stirring speed, and initial pH values. Up to 99.2% of 2,4-DCP was removed after 300 min reaction with these conditions: Pd loading percentage over Fe 0 0.3 wt.%, initial 2,4-DCP concentration 20 mg L −1 , Pd/Fe dosage 3 g L −1 , initial pH value 3.0, and reaction temperature 25 °C. The degradation of 2,4-DCP followed pseudo-first-order kinetics reaction and the apparent pseudo-first-order kinetics constant was 0.0468 min −1 .
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CHINESE JOURNAL OF CATALYSIS
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2014
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IF 1.552
Guoqiang Song,Zhiqing Wang,Liang Wang,Guoru Li,Minjian Huang,Fengxiang Yin
Effective bifunctional catalysts play a vital role in large-scale commercial applications of rechargeable lithium-air batteries. In this article, a metal-organic framework, MOF(Fe), was prepared by a hydrothermal process using ferric nitrate as the metal ion precursor and trimesic acid as an organic ligand. The structure of the MOF(Fe) was characterized by X-ray diffraction, N 2 adsorption-desorption, Transmission electron microscopy, Fourier transform infrared spectroscopy and Thermo-gravimetric analysis. The activity for the oxygen reduction reaction (ORR) and the kinetic behavior of the ORR using the MOF(Fe) were investigated by cyclic voltammetry and rotating disk electrode voltammetry, respectively, using an alkaline electrolyte. The characterization results showed that the MOF(Fe) was highly crystalline with abundant micropores, large specific surface area and high thermal stability. The MOF(Fe) exhibited excellent catalytic activity for the ORR. The ORR mechanism varies with the applied potentials. The ORR occurs through a two-electron pathway at potentials in the range of −0.30 to −0.50 V, but shifts to four-electron pathway with the potentials in the range −0.50 to −0.95 V. In addition, the MOF(Fe) shows excellent catalytic activity for the oxygen evolution reaction (OER) in an alkaline electrolyte. This work opens a new route for the development of effective non-precious metal catalysts based on MOFs for the ORR and OER.
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DALTON TRANSACTIONS
·
2015
·Vol. 44
·期 41
·18227-18236
·
IF 4.197
Ruowen Liang,Rui Chen,Fenfen Jing,Na Qin,Ling Wu
H3PMo12O40 molecules have been successfully encapsulated in the cavities of MIL-100(Fe) via a facile hydrothermal method (denoted as HPMo@MIL-100(Fe)). A series of characterization has corroborated the insertion of H3PMo12O40 within the cavities of MIL-100(Fe). The resulting HPMo@MIL-100(Fe) nanocomposites have exhibited much higher photoactivity than the original-MIL-100(Fe) toward the photocatalytic selective oxidation of benzylic alcohols and the reduction of Cr(VI) under visible light irradiation (λ ≥ 420 nm). The higher photoactivity of HPMo@MIL-100(Fe) can be attributed to the integrative effect of enhanced light absorption intensity and more efficient separation of photogenerated electron–hole pairs. The host porous structure of MIL-100(Fe) can achieve a uniform composition with H3PMo12O40, which is significantly important for producing highly reactive dispersed H3PMo12O40 molecules and enhancing the photocatalytic activity of HPMo@MIL-100(Fe) nanocomposites. And the immobilized H3PMo12O40 molecules are more convenient for recycling. Importantly, almost no Fe and Mo ions leach from the MIL-100(Fe) during the reaction, which verifies the photostability of the HPMo@MIL-100(Fe). In addition, possible photocatalytic redox reaction mechanisms have been investigated.
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