FUEL
·
2018
·
IF 4.908
Yu Chen,Xin Guo,Fan Wu,Yu Huang,Zhanchi Yin
Hematite (α-Fe 2 O 3 ) has been proved to be a promising sorbent for mercury removal in various situations. The mercury removal performance of α-Fe 2 O 3 was investigated using a simulated coal gasification syngas containing Hg 0 , N 2 , HCl, and/or H 2 S, a series of experiments were designed with HCl and H 2 S separately and both employed. For a better understanding in the interaction between HCl and H 2 S in mercury removal, the differences in mercury oxidation were demonstrated on the basis of density functional theory calculations. The rate-limiting step in HgCl 2 formation is Hg 0 → HgCl with the energy barrier of 139.47 kJ/mol, but for H 2 S in mercury oxidation, the generation of active sulfur species is the key step and the rate-limiting step is detachment of second H with an energy barrier of 57.53 kJ/mol. Experimental results point that HCl has inhibition on H 2 S for mercury removal, it may be ascribed to the competition of active Fe sites on Fe 2 O 3 . Conversely, HCl contributes to the mercury oxidation at high temperature while H 2 S has a limit effect at elevated temperature.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2018
·
IF 5.091
Ling Cheng,Yulu Tian,Jingdong Zhang
A p-n heterojunction film of Cu 2 O/α-Fe 2 O 3 was constructed by electrodepositing p-type Cu 2 O microcubes on liquid phase deposited film of n-type α-Fe 2 O 3 . The surface morphology , the crystal phase and composition of Cu 2 O/α-Fe 2 O 3 heterojunction film were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The enhanced absorption in the visible light region was observed in UV–visible diffuse reflectance spectra. Meanwhile, an efficiently improved separation and faster transfer of photogenerated electrons and holes were revealed by photoluminescence spectra and electrochemical impedance spectra. The Cu 2 O/α-Fe 2 O 3 p-n heterojunction was applied to photoelectrocatalytic degradation of oxytetracycline at a bias potential of +0.5 V under visible light illumination. After 60-min photoelectrocatalytic treatment, 73.3% of oxytetracycline was removed and the degradation rate constant reached 2.14 × 10 −2 min −1 . Moreover, the crystal phases and compositions for the used and fresh Cu 2 O/α-Fe 2 O 3 films were studied, and a possible photoelectrocatalytic mechanism was proposed.
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POLYMER
·
2018
·
IF 3.483
Xi-Chuan Li,Chuan-Shan Hu,Hui-Juan Li,Peng-Yun Li,Abdul Haleem,Wei-Dong He
Ring-opening polymerization (ROP) of N-carboxy-α-amino acid anhydride (NCA) of γ-benzyl l -glutamate (BLG) was investigated under frozen condition for the first time. This cryo-ROP was performed in DMSO or 1,4-dioxane below the freezing point of polymerization mixture. The kinetics was monitored with proton nuclear magnetic resonance spectroscopy and gel permeation chromatography , disclosing the well control over molecular weight , living polymerization features and considerable polymerization rate. Compared with the polymerization proceeded at 30 °C, which showed weak linearity regarding the reaction kinetics and relatively broad distribution of molecular weight, the cryo-ROP exhibited excellent first-order kinetics as well as narrow molecular distribution.
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ADVANCED SYNTHESIS & CATALYSIS
·
2018
·Vol. 361
·期 4
·803-812
·
IF 5.123
Xinjian Yin,Yayun Liu,Lijun Meng,Haisheng Zhou,Jianping Wu,Lirong Yang
Glutamate dehydrogenases (GluDHs) are promising biocatalysts for the synthesis of chiral α-amino acids by asymmetric reductive amination of α-keto acids. However, their strict substrate specificity limits their applications. To address this problem, we developed a molecular engineering method for GluDHs that enhances the asymmetric reductive amination of bulky α-keto acids. Based on rational design, a “cave” located in the active site pocket of Pp GluDH (GluDH from Pseudomonas putida ), which plays an essential role in substrate recognition, was tailored to facilitate the accepting of bulky substrates. Two mutants (A167G and V378A) were discovered to have significantly enhanced catalytic activity toward 2-oxo-4-[(hydroxy)(methyl)phosphinyl]butyric acid (PPO) and several other bulky substrates. This molecular engineering method was then applied to ten other GluDHs from different sources and with different properties. All engineered GluDHs acquired substantial improvements in PPO-oriented catalytic activity. The most efficient mutant of NADP + (nicotinamide adenine dinucleotide phosphate)-specific GluDHs showed up to 1820-fold increased activity and the specific activity reached 111.02 U/mg-protein. The NAD + (nicotinamide adenine dinucleotide)-specific GluDHs, which have no detectable wild type activity toward PPO, acquired a considerable level of activity (1.90–29.48 U/mg-protein). In batch production of L-phosphinothricin, these “cave-tailored” GluDHs exhibited markedly improved catalytic efficiencies compared with their wild types and ee values of >99%. The space-time yields (STY) varied from 818.16 to 1482.96 g ⋅ L −1 ⋅ d −1 , suggesting potential practical applications of these mutants.
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JOURNAL OF POROUS MATERIALS
·
2018
·Vol. 26
·期 4
·961-970
·
IF 1.858
Sun Hao,Wang Ao,Sun Kang,Jiang Jianchun,Wang Fang,Gu Zhenggui
Hierarchical HBEA catalysts were fabricated through alkaline treatment and evaluated in a fixed-bed reactor. The relative crystallinity, pore property, Si/Al molar ratio, coke formation and structure of catalysts were investigated by the methods including X-ray diffraction, N 2 physisorption, X-ray fluorescence, thermogravimetric analysis and transmission electron microscope, respectively. The acidity of catalysts was studied by Fourier transform infrared spectrometry using pyridine as the probe molecule. These results demonstrated that pure NaOH treatment improved the mesoporosity of catalyst, while decreased the β -methylnaphthalene selectivity and catalyst stability due to the partially destroyed framework and an increase in the concentration of Lewis acid sites. The Lewis acid sites are responsible for the hydride transfer and subsequent reaction that form coke. In contrast, the presence of tetra-propyl-ammonium hydroxide in the mixed-alkali treatment resulted in regular mesopores development, preserved intrinsic zeolite properties and Lewis sites proportion, leading to the maintained β -MN selectivity and coke deposition rate. The increased mesoporosity and strong Brönsted acid sites amount per number of coke were responsible for the improved coke tolerance of mixed-alkali treated HBEA, and thus its deactivation rate was 41.7% lower than that of HBEA catalyst.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2018
·
IF 3.909
Mengting Wang,Jinyuan Shi,Lei Wang,Yaqin Hu,Xingqian Ye,Donghong Liu,Jianchu Chen
In this study, lotus leaf flavonoids (LLF) were found to show a notable inhibition activity on α-amylase in a mixed-type manner with IC 50 value of (5.58 ± 0.10) mg/mL. The intrinsic fluorescence of α-amylase was quenched by the interaction with LLF through a static quenching mechanism, and LLF-α-amylase complex was spontaneously formed mainly driven by the hydrophobic interaction and hydrogen bonding. Multispectroscopic analyses (synchronous fluorescence, three-dimensional fluorescence, circular dichroism (CD) and fourier transform infrared spectra (FT-IR)) comprehensively demonstrated that the binding of LLF to α-amylase would change the conformation and microenvironment of α-amylase, resulting in inhibiting the enzyme activity. The present study indicated that LLF had potential to be as an ingredient in functional food for the prevention of type-2 diabetes.
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BIORESOURCE TECHNOLOGY
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2018
·
IF 5.807
Jiatong Jiang,Hairong Wu,Yao Lu,Tao Ma,Zhe Li,Derong Xu,Wanli Kang,Baojun Bai
The performance and de-emulsification mechanism of α-amylase, a novel environmental friendly biodemulsifier in petroleum industry, was investigated at room temperature. The effects of α-amylase on the viscosity of amphiphilic polymer solution and de-emulsification rate were studied by changing the concentration of α-amylase, temperature and salinity. Polymer molecular weight, Zeta potential, interfacial film strength and interfacial tension were measured to investigate the de-emulsification mechanism of α-amylase. The results show that α-amylase is an efficient biodemulsifier to increase the de-emulsification rate of amphiphilic polymer emulsions. Hydrolysis of α-amylase to amphiphilic polymers destroys the structure of the amphiphilic polymer, thereby reduces the viscosity and the interfacial film strength of the system. Once de-emulsification is completed, the lower layer, i.e. the emulsified layer, will be clear. Thus, α-amylase can be applied as an effective de-emulsifier for amphiphilic polymer-stabilized O/W emulsion.
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CHINESE SCIENCE BULLETIN
·
2012
·Vol. 58
·期 7
·708-712
·
IF 1.321
Liu LiHong,Zhou XiaoBing,Xie Rong-Jun,Huang Qing
Pure Ca-α-SiAlON:Eu 2+ was synthesized by microwave sintering method at a relatively low temperature of 1550°C. Photoluminescence intensity of the resultant phosphor was higher than those of the samples synthesized by conventional gas-pressure sintering technique at 1750°C. When it was excited at 450 nm, the as-prepared yellow Ca-α-SiAlON:Eu 2+ sample had an external quantum efficiency of 42%, comparable to the sample synthesized at 1750°C under 0.5 MPa N 2 gas pressure by the GPS method reported in reference. The experimental results demonstrated that the microwave sintering method was also an interesting approach for synthesizing nitride phosphors, which promises lower firing temperature than those by carbothermal reduction and nitridation (CRN) methods, higher heating rate and shorter duration time compared with those by gas-pressure sintering.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2013
·
IF 3.172
Shaofeng Zhang,Feng Ren,Wei Wu,Juan Zhou,Lingling Sun,Xiangheng Xiao,Changzhong Jiang
Composite photocatalysts that consist of semiconductor and noble metal nanostructures have been considered to be the promising and crucial materials for straightforward improving the efficiency in photocatalytic process and for the conversion of solar to chemical energy. In this work, we fabricated Ag-α-Fe 2 O 3 hybrid composites through a self-catalytic growth method by using the aldehyde-modified spindle α-Fe 2 O 3 nanoparticles (NPs) as supports. The size of supported Ag NPs can be directly controlled on the surface of α-Fe 2 O 3 . The morphology and structure of the resulting Ag-α-Fe 2 O 3 hybrid composites were studied by various techniques, including SEM, TEM, and XRD. The distinct photocatalytic behaviors were examined through the photodegradation of RhB dye. It was found that with the Ag NPs, the photocatalytic activities were enhanced greatly and the size of the Ag NPs played a crucial influence on the photocatalytic behaviors of the Ag-α-Fe 2 O 3 composites.
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ORGANIC & BIOMOLECULAR CHEMISTRY
·
2015
·Vol. 13
·期 26
·7323-7330
·
IF 3.562
Kelu Yan,Daoshan Yang,Wei Wei,Jing Zhao,Yuanyuan Shuai,Laijin Tian,Hua Wang
A novel, efficient, and catalyst-free strategy has been initially developed for the construction of thioesters via the direct radical oxidative decarboxylation of α-keto acids with thiols, and the corresponding target products were obtained in moderate to good yields. It offers an alternative approach for the synthesis of useful diverse thioesters.
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MATERIALS LETTERS
·
2014
·
IF 2.269
Jing-He Yang,Chao Wang,Duo Yang,Xingyun Li,Peng Shang,Yamin Li,Ding Ma
The boron-doped α-Ni(OH) 2 nanoflowers (B-α-Ni(OH) 2 ) with high specific surface area (400 m 2 g −1 ) were synthesized by the one pot liquid-phase method using P123 (EO 20 PO 70 EO 20 ) as template and NaBH 4 as alkali and boron sources. The size of the B-α-Ni(OH) 2 nanoflowers is about 300 nm and there are many porous. The 50 nm nanoplates are the basic structure units of nanoflowers and thickness of the nanosheets is approximately 5 nm. The content of B is about 15% among the Ni, B, O elements and boron exists mainly in the form of BO 2 − , which was confirmed by XPS characterization. B-α-Ni(OH) 2 nanoflowers exhibit a high specific capacitance of ~2296 F g −1 at a charge and discharge current density of 3 A g −1 with excellent cycling ability. The high specific capacitance and remarkable rate capability are promising for applications of B-α-Ni(OH) 2 nanostructures as advanced electrochemical capacitor materials with both high energy and cycling ability.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2017
·
IF 6.198
Xufang Qian,Meng Ren,Yao Zhu,Dongting Yue,Yu Han,Jinping Jia,Yixin Zhao
A novel α-FeOOH/mesoporous carbon (α-FeOOH/MesoC) composite prepared by in situ crystallization of adsorbed ferric ions within carboxyl functionalized mesoporous carbon was developed as a novel visible light assisted heterogeneous Fenton-like catalyst. The visible light active α-FeOOH nanocrystals were encapsulated in the mesoporous frameworks accompanying with surface attached large α-FeOOH microcrystals via C–O–Fe bonding. Assisting with visible light irradiation on α-FeOOH/MesoC, the mineralization efficiency increased owing to the photocatalytic promoted catalyzing H2O2 beyond the photothermal effect. The synergistic effect between α-FeOOH and MesoC in α-FeOOH/MesoC composite improved the mineralization efficiency than the mixture catalyst of α-FeOOH and MesoC. The iron leaching is greatly suppressed on the α-FeOOH/MesoC composite. Interestingly, the reused α-FeOOH/MesoC composites showed much higher phenol oxidation and mineralization efficiencies than the fresh catalyst and homogeneous Fenton system (FeSO4/H2O2). The XPS, XRD, FTIR, and textural property results reveal that the great enhancement comes from the interfacial emerged oxygen containing groups between α-FeOOH and MesoC after the first heterogeneous Fenton-like reaction. In summary, visible light induced photocatalysis assisted heterogeneous Fenton-like process in the α-FeOOH/MesoC composite system improved the HO• production efficiency and Fe(III)/Fe(II) cycle and further activated the interfacial catalytic sites, which finally realize an extraordinary higher degradation and mineralization efficiency.
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