RAPID COMMUNICATIONS IN MASS SPECTROMETRY
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2018
·Vol. 32
·期 21
·1897-1904
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IF 1.97
An Li,Qiusheng Chen,Ligang Pan,Jieqiong Dong,Xinxin Jin
Rationale The stable nitrogen isotopic composition of nitrate (NO 3 − ) can be an effective tool to identify NO 3 − sources and understand nitrogen cycling. However, the usefulness of this isotopic tool in environment research has been limited by complex analytical procedures for the nitrogen isotopic analysis of NO 3 − . We aimed to develop a novel method for the simple and rapid measurement of the δ 15 N value of NO 3 − in water. Methods Water NO 3 − was transformed into nitrobenzene for nitrogen isotopic analysis by gas chromatography–combustion–isotope ratio mass spectrometry (GC/C-IRMS). The derivatization procedure was optimized to maximize the nitrobenzene yield. 1.5-fold 98% sulfuric acid and 0.5-fold benzene with respect to the water sample were used to derive nitrobenzene with only 1 min of vortex at room temperature. The nitrobenzene derivatization product (dissolved in benzene) was then separated by GC, followed by combustion to N 2 for δ 15 N analysis by IRMS. Results The minimum amount of nitrogen required for accurate determination of the δ 15 N value was 8.6 ng at an m/z 28 intensity of 150 mV. The standard deviation of the GC/C-IRMS method was ≤0.5‰ (three replicates) even at a low NO 3 − concentration of 9.58 mg L −1 . The various standards and samples with different δ 15 N values exhibited good agreement with the assigned δ 15 N values obtained by using the proposed method. Conclusions Compared with previous methods, the newly developed method provided shorter analysis time and easy operation, and eliminated the need for the removal of chloride and nitrite. The GC/C-IRMS derivatization method offers a fully operational tool for δ 15 N measurement of NO 3 − in water.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2018
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IF 3.412
Yu Zhang,Yuping Liu,Wenxi Yang,Jia Huang,Yingqiao Liu,Mingquan Huang,Baoguo Sun,Changlin Li
To characterize potent odor-active compounds in preserved egg yolk (PEY), volatile compounds were isolated by headspace solid-phase microextraction and solvent-assisted flavor evaporation. Gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS) analyses identified a total of 53 odor-active compounds by comparing the odor characteristics, MS data, and retention indices with those of reference compounds. Twenty-seven odorants were detected in at least five isolates that were extracted and analyzed by the same method, and their flavor dilution (FD) factors, ranging from 1 to 2048, were measured by aroma extract dilution analysis (AEDA). To further determine their contribution to the overall aroma profile of PEY, 22 odorants with FD factors ≥16 and GC–MS responses were quantitated, and their odor activity values (OAVs) were calculated. According to the OAV results, 19 odorants with OAVs ≥ 1 are the potent odorants that greatly contribute to the characteristic aroma of PEY. Nine compounds were identified for the first time: (E,Z)-2,6-nonadienal, (E)-2-nonenal, 2-methylbutanal, dimethyl disulfide, trimethylamine, methional, dimethyl trisulfide, diisopropyl disulfide, and diethyl disulfide.
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JOURNAL OF CATALYSIS
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2018
·
IF 6.759
Jian-Dong Song,Tong-Yang Song,Ting-Ting Zhang,Yun Wang,Meng-Fei Luo,Ji-Qing Lu
A series of supported V 2 O 5 /MgF 2 catalysts were prepared and tested for dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) to synthesize 1,3,3,3-tetrafluoropropene (HFO-1234ze). The addition of V 2 O 5 in MgF 2 resulted in up to 5-fold increase in HFC-245fa conversion (from 19.2 to 95.2%) and much enhanced catalyst stability. Characterization results revealed that the dehydrofluorination initiated on the MgF 2 support triggered the transformation of V 2 O 5 to vanadium oxyfluoride (VOF x ) species via the reaction between V 2 O 5 and HF, and such species were responsible for the improved activity as they had much higher turnover frequencies (TOFs) than the MgF 2 (0.762 s −1 v.s. 0.026 s −1 at 320 °C). The kinetic results indicated that the 3.1V 2 O 5 /MgF 2 had much lower activation energy (44.6 ± 1.9 kJ mol −1 ) than the MgF 2 (69.0 ± 0.8 kJ mol −1 ). Accordingly, reaction mechanism on the V 2 O 5 /MgF 2 catalyst was proposed, which included slow dehydrofluorination on MgF 2 and fast dehydrofluorination on the VOF x species.
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FUEL
·
2017
·
IF 4.601
Yiquan Guo,Yongchun Zhao,Shaolong Wang,Cheng Jiang,Junying Zhang
Fly ash fine particles emitted from flue gas during coal combustion are the primary atmospheric pollutants in China. The purpose of this study was to investigate the characteristics of the zeta potential of fine particle suspensions. The relationship between the zeta potential and the fine particle removal efficiency was also discussed. Batch experiments were conducted to evaluate the zeta potential of fine particle aqueous solutions under various pH, ion concentration, surfactant, polymer, and chemical agglomeration solution conditions. A chemical agglomeration system was designed to simulate the removal process of the fine particles. The test results indicated that the zeta potential absolute value of the solution decreased initially and then increased as the pH increased. As the pH increased from 4 to 12, the zeta potential decreased from Zp = 9.4 mV to Zp = −45.4 mV. The isoelectric point (IEP) was 4.3. Also at the IEP, the highest fine particle removal efficiency of 25.9% was achieved. The zeta potential increased as the metal cation concentration of the solutions increased. The trivalent cation Al 3+ exhibited the best performance, which increased Zp from −32.1 mV to −11.2 mV and produced the highest fine particle removal efficiency of 9.2%. Polymers significantly impacted the zeta potential. As the concentration of kappa-carrageenan (CAR) increased from 0.01% to 5%, the zeta potential increased from −30.1 mV to 12.6 mV. The highest fine particle removal efficiency of 41.8% was acquired at a concentration of 0.5%, which had the lowest zeta potential absolute value of 3.5 mV. It can be inferred that the increase in the zeta potential induced the growth of the energy barrier, which prevented particle agglomeration. The suspension with a lower zeta potential exhibited a better fine particle removal efficiency.
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FUEL
·
2017
·
IF 4.601
Yafei Guo,Chuanwen Zhao,Jian Sun,Weiling Li,Ping Lu
Silica aerogel supported K 2 CO 3 sorbents with different K 2 CO 3 loadings were synthesized by sol-gel and wet impregnation processes. The sorbents were characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) techniques. CO 2 capture performances of the sorbents were tested in a simulated ultra-dilute flue gas stream of 1.0%CO 2 and 2.0%H 2 O at 20 °C, using a fixed-bed reactor coupled with an online infrared gas analyzer. Sorbent regeneration performances of the samples were evaluated in a pure N 2 atmosphere at 200 °C with a heating rate of 10 °C/min. CO 2 capture capacity and K 2 CO 3 utilization efficiency increased first and then decreased with the increase in K 2 CO 3 loading. The desired sorbent with 20 wt% K 2 CO 3 was screened for investigating the effects of acid impurities. The presence of 500 ppm SO 2 and 500 ppm NO in the simulated flue gas stream was found to adversely affect the CO 2 capture, sorbent regeneration and multiple cyclic performances. Detailed mechanisms of the irreversible sorbent deactivation process were discussed. SO 2 could be chemically absorbed by K 2 CO 3 under a moist condition to form byproduct of K 2 SO 3 ·H 2 O, and the byproduct was stable and would be accumulated in the sorbent during the repeated cycles. This further attenuated the physical properties and K 2 CO 3 utilization efficiency of the sorbent. These results would lay a solid foundation for further application of the sorbent in ultra-dilute flue gas treatment.
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CHEMICAL ENGINEERING SCIENCE
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2017
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IF 2.895
Rong Chen,Hao Feng,Xun Zhu,Qiang Liao,Dingding Ye,Jian Liu,Ming Liu,Gang Chen,Kun Wang
Visualization study on the interaction of the Taylor flow behavior and the catalytic activity in a gas-liquid-solid microreactor for nitrobenzene hydrogenation was performed under the long-term operation. The results showed that the gas slug length was first declined rapidly due to hydrogen consumption and then almost unchanged along the flow direction. After operating with a few hours, the variation of the gas slug length became obscure at the upstream due to the nanocatalyst deactivation but obvious at the downstream. Finally, the gas slug length was nearly unchanged. Corresponding to the long-term operation, the nitrobenzene conversion was first kept stable and then gradually declined, which well responded to the flow behaviors. Besides, effects of the inlet nitrobenzene concentration and flow rates on the flow behaviors were also explored. This work reveals the inherent interaction between the Taylor flow behavior and catalytic reaction under the long-term operation.
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JOURNAL OF APPLIED POLYMER SCIENCE
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2017
·Vol. 135
·期 10
·45728
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IF 1.86
Cuijia Duan,Xingming Jie,Haitao Zhu,Dandan Liu,Weiming Peng,Yiming Cao
With MOFs of Cu 3 (BTC) 2 and ZIF-8 as the dispersed phases and four polyimides with CO 2 permeabilities ranging from 1.36 to 564 barrer as the continuous phase, the influence of metal organic frameworks on the gas-separation properties of mixed-matrix membranes (MMMs) was investigated. The results show that the gas permeabilities of all of the prepared MMMs greatly increased and even largely exceeded the predicted value of the Bruggeman model; for example, with the same Cu 3 (BTC) 2 loading of 21.3 vol %, the O 2 permeability increase rate of our prepared Cu 3 (BTC) 2 /Matrimide 5218-20 MMMs was 2.26 times, whereas that predicted by the Bruggeman model was only 1.05 times. In addition, when the gas permeability of the polymeric phase was far lower than the dispersed phase of ZIF-8 or Cu 3 (BTC) 2 compared with ZIF-8, which had a particle size ( R ) around 150 nm, Cu 3 (BTC) 2 of 5–15 µm showed a little better enhancing effect on the gas-permeation performance of the MMMs. In addition to the properties of the dispersed and continuous phases, we speculated that the ratio between R of the dispersed phase to the membrane thickness ( L ) played an important role for MMMs; the larger R / L was, the greater the gas permeability of the MMMs was. This speculation was initially evidenced by the ZIF-8/ODPA/TMPDA-20 MMMs with different L s. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 45728.
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CHEMICAL ENGINEERING JOURNAL
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2017
·
IF 6.216
Jian Liu,Xun Zhu,Qiang Liao,Rong Chen,Dingding Ye,Hao Feng,Ming Liu,Gang Chen
In this study, the layer-by-layer self-assembly technique was employed to synthesize the Pd nanocatalysts on the polyelectrolytes thin film of PAH-PSS grafted on the polydopamine functionalized surface for the development of the gas-liquid-solid microreactor. The utilization of this technique not only allows for strong adhesion of PAH-PSS on polydopamine to form a (PAH-PSS)/PDA thin film but also enables efficient adsorption of the precursor via electrostatic interactions for the nanocatalyst synthesis. The chemical composition and morphology characterizations indicated that Pd nanoparticles could be uniformly dispersed over the polyelectrolytes thin film of PAH-PSS. Experimental results on the nitrobenzene hydrogenation showed that the newly-developed microreactor with the Pd nanocatalysts deposited on the (PAH-PSS)/PDA yielded high conversion and much better durability than did the one with the Pd nanocatalysts directly coated on the PDA. Three main reasons contributed to the improved performance: (i) the increase of the catalyst loading arising from more effective precursor adsorption for synthesizing Pd nanocatalysts, (ii) the alleviation of nanocatalysts migration and agglomeration, (iii) the reduction in the adsorption of generated intermediates/by-products. Parametric studies revealed that if the supply of hydrogen was sufficient, the change of the gas flow rate showed little effect on the performance. When the liquid flow rate and inlet nitrobenzene concentration were too high, not only the conversion but also the durability were decreased. The reduction of the liquid flow rate and inlet nitrobenzene concentration led to the enhancement of the durability. This work opens a window for fabricating the high-performance gas-liquid-solid microreactors.
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ACS Sustainable Chemistry & Engineering
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2017
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IF 5.951
Yu Long,Ruoyu Zhang,Juncheng Huang,Jinggang Wang,Yanhua Jiang,Guo-hua Hu,Jian Yang,Jin Zhu
A biobased poly(butylene 2,5-furan dicarboxylate) (PBF) is synthesized and blended with poly(lactic acid) (PLA). With only 5 wt % addition of PBF, the elongation at break of PLA becomes 18.5 times more than before, while the tensile modulus and tensile strength at yield keep almost the same. Morphological analysis based on scanning electron microscope pictures shows drastic shape deformation of PBF dispersed phases from sphere to fibril. The elongation ratio of PBF phase is much larger than that of PLA matrix, which is caused by a possible “plastic-rubber” transition in PBF during stretch process. On the other hand, stretch induced crystallization in PBF happened and it may increase the modulus of PBF along the tensile direction. Probably with the above two phenomena, PLA is dynamically toughened and strengthened in the elongation procedure. Moreover, the impact strength of the blends is better than those of the two pure components, and rubber-plastic transition and crystallization of PBF could improve the impact toughness too. The gas barrier property of PLA/PBF blends is also significantly enhanced by the introduction of a furan ring. It can be concluded that PLA/PBF blends are a good base material with great potential for future development in different areas.
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JOURNAL OF CHROMATOGRAPHY A
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2012
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IF 4.531
Guowen Chen,Wenjie Li,Chen Zhang,Chuanjian Zhou,Shengyu Feng
Phenyl-ended hyperbranched carbosilane (HBC) is synthesized and immobilized onto the inner wall of a fused silica capillary column using a sol–gel process. The hybrid coating layer formed is used as a stationary phase for gas chromatography (GC) and as an adsorption medium for solid phase microextraction (SPME). Trifluoroacetic acid , as a catalyst in this process, helps produce a homogeneous hybrid coating layer. This result is beneficial for better column chromatographic performances, such as high efficiency and high resolution. Extraction tests using the novel hybrid layer show an extraordinarily large adsorption capacity and specific adsorption behavior for aromatic compounds . A 1 ppm trace level detectability is obtained with the SPME/GC work model when both of the stationary phase and adsorption layer bear a hyperbranched structure. A large amount of phenyl groups and a low viscosity of hyperbranched polymers contribute to these valuable properties, which are important to environment and safety control, wherein detection sensitivity and special adsorption behavior are usually required.
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SENSORS AND ACTUATORS B-CHEMICAL
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2024
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IF 8
Hairui Fang,Jiawei Zhang,Eryang Shang,Hong Chen,Xiao Ma,Xingyu Kang,Huizhang Zhao,Yuxia Liu,Dong Wang
Metal oxides are widely used because of their simple structure, low price, and excellent gas-sensitive properties. But now, the metal oxide sensor faces two challenges. One is that when the detection limit of the sensor is low, it will be affected by a high concentration of gas and fail in practical applications. Second, the metal oxide sensor is susceptible to temperature changes, resulting in inaccurate measurement results. To address the above problems, the performance of metal oxides is enhanced through doping. Indium oxide doped with various levels of indium molybdate was prepared using a two-step hydrothermal method resulting in a composite material with an n-n heterostructure. The interaction formed by the n-n heterostructure enhances the redox reaction between NO 2 gas and the sensor, and the unique nano cluster structure provides more active sites for the sensor, significantly improving the gas performance of the sensor towards NO 2 . Sensors based on In 2 (MoO 4 ) 3 with a doping ratio of 4 % (the sample IM3) showed excellent gas sensitivity. The lower and upper detection limits of the sensor are 200 ppb (response is 1.46) and 150 ppm (response is 515.94), respectively. And the sensor has good resistance to ultra-high concentration (10000 ppm) nitrogen dioxide (NO 2 ) impact. In the range of 130–170°C, the temperature has a small and linear effect on the sensor response, which is very beneficial for temperature correction of gas sensors. The sensor prepared by In 2 (MoO 4 ) 3 doped In 2 O 3 composite material has a good potential for application in engineering practice.
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SENSORS AND ACTUATORS B-CHEMICAL
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2024
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IF 8
Bingliang Wang,Yongjiao Sun,Yimeng Dong,Yuchen Hou,Zhiyuan Lu,Zihan Wei,Wendong Zhang,Koichi Suematsu,Jie Hu
The construction of a novel Au nanoparticles loaded In 2 S 3 /In 2 O 3 hybrid microflowers composite was conducted through a well-designed hydrothermal and partial oxidation method and used for NO 2 sensing at room-temperature (RT). The characterization data confirmed the hybrid structures and demonstrated that the ratio of adsorbed oxygen species on the surface increased after partial oxidation. The sensing performance of flexible gas sensors based on In 2 S 3 /In 2 O 3 , In 2 O 3 , Au x In 2 S 3 /In 2 O 3 (x = 0.5, 1 and 2 wt%) were tested and compared at RT. Heterostructure construction and Au NPs loading significantly improved the sensing properties at RT. Peculiarly, the response value of 1 wt% Au NPs loaded In 2 S 3 /In 2 O 3 (Au 1 In 2 S 3 /In 2 O 3 ) sensor for 100 ppm NO 2 at RT was 20.7, which was 9.2 times higher than that of In 2 O 3 sensor. Meanwhile, it also possessed excellent selectivity, fast response/recovery time (12/27 s), good repeatability, long-term and mechanical stability. The outstanding sensing performance for NO 2 at RT mainly associated to the heterojunction between In 2 S 3 and In 2 O 3 and the catalytic effect of Au NPs. Finally, density functional theory (DFT) was used to calculate and analyze the gas adsorption and charger transfer, which related to the enhanced sensing performance.
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