Journal of Chemistry
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2020
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IF 1.79
Yuchen Ya,Xiaokang Nie,Licheng Peng,Longkai Xiang,Jialong Hu,Wenlong Dong,Huaqiang Chu
Laminar diffusion flame was used to study the effect of ethanol on n-heptane flame in terms of the morphology and microstructure of soot under atomization combustion. For the same carbon mass flux at the outlet of the burner, the ratio of ethanol doping in n-heptane was changed, and the soot was collected from the axial positions of the flame at different heights using the thermophoresis probe method. The results showed that the flame height increased significantly with the increasing ratio of ethanol doping. When the ratio of ethanol and n-heptane (CE/CN) was 1.5, the flame height increased by 10 mm compared with that of pure n-heptane flame. Besides, the temperature in the center of the flame decreased with the increasing ratio of ethanol doping, but the temperature in the low position was higher than that in the pure n-heptane flame, and the temperature in the high position was lower than that in the pure n-heptane flame. However, the flame temperature was the highest when the proportion of ethanol in the mixture was greater than that of n-heptane. The temperature at the flame center decreased with the increasing ratio of ethanol doping, while the temperature at the flame edge increased with the ratio. The primary particle size of soot (soot size hereafter) in all working conditions increased with the increase of flame height, which was in line with the general growth law of soot. Moreover, the soot size at the same height decreased with the increasing ratio of ethanol doping, and this trend was most obvious at the flame height of 20 mm and 30 mm. Compared with pure n-heptane, when CE/CN was 1.5, the soot size at 20 mm and 30 mm decreased by an average of 34.83%, indicating that ethanol could inhibit the surface growth of soot particle. Furthermore, the density of soot particles collected by a single copper net decreased significantly, indicating that ethanol could reduce the production amount of soot.
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CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Yi Xia,Jie Shi,Qian Sun,Dan Wang,Xiao-Fei Zeng,Jie-Xin Wang,Jian-Feng Chen
Colloidal nanocrystals can offer exquisite control of physical and chemical properties for technological applications by tuning their sizes, shapes and crystal forms. Herein, a convenient phase-transfer route was presented to controllably prepare transparent dispersions of monodispersed ZrO 2 nanocrystals in an aqueous-organic two-phase medium. By adjusting the surfactants, solvents and basicity, the controllability of crystal forms from monoclinic to tetragonal phases, the particle length from 5 to 20 nm, and the different shapes including spindle, cobblestone, sphere, branch, rod and cube can be achieved. The as-prepared ZrO 2 nanocrystals can be readily dispersed in nonpolar solvents, thereby forming the ultra-highly concentrated (60 wt%), highly stable (>18 months) and highly transparent nanodispersions. Density functional theory (DFT) calculations were further used to elucidate the root causes of underpinning growth mechanisms. This work not merely enriches the methodology of controllable fabrication of monodispersed sub-10 nm ZrO 2 nanocrystals, but also enables a platform to synthesize rare-earth-doped nanophosphors using ZrO 2 as the host matrix. The fluorescent ZrO 2 :Yb 3+ /Er 3+ nanocrystals, which can be easily monodispersed in organic solvents, were also prepared with visible luminescene properties under near-infrared irradiation.
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高影响因子
CHEMICAL ENGINEERING SCIENCE
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2020
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IF 3.871
Jiayuan Wang,Wenqi Cao,Lingyu Zhu,Jianli Wang,Richard Lakerveld
The crystal size distribution (CSD) is an important quality attribute of pharmaceutical crystals. An emulsion is an attractive system to enable improved control over the CSD compared to conventional bulk crystallization by confining the crystal formation and growth. However, the method is currently challenged by inhibition of nucleation in small droplets and a lack of confinement of growing crystals. Cooling crystallization of a pharmaceutical inside the droplets of an oil-in-water emulsion is investigated. The droplet size is optimized to avoid the strong inhibition of nucleation and to minimize a lack of confinement of growing crystals. Furthermore, the influence of the type of surfactant and the hydrodynamic conditions on the CSD are investigated. The results demonstrate how the inhibition of nucleation in emulsion droplets due to the small-volume effect can be mitigated and how confinement can be improved, which is important for improved control over the CSD.
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高影响因子
THERMOCHIMICA ACTA
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2020
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IF 2.762
Yuxin Zheng,Chen Zhang,Haihua Liu
A new flow calorimeter is developed to analyze the isobaric heat capacity of liquid. The characteristics of calorimeter have been studied at temperatures from 293 K to 353 K and pressures from 0.1 MPa to 15 MPa. The design of the calorimeter includes the innermost part of the calorimeter with two thick-walls, aluminum shields and microheater. The function of thick-walls with aluminum shields is to replace the conventional constant temperature bath for minimizing heat loss and precisely controlling the temperature of calorimeter. In order to verify the feasibility and reliability of the apparatus, the heat loss is checked by pure water under given pressure and various temperatures. The heat capacity of toluene, heptane and cyclohexane are measured at various temperatures and pressures. The experimentally measured data as a whole is in good agreement with the literature values available. Compared with the literature data, the experimental results by using the new calorimeter show that the deviations are less than 2%.
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JOURNAL OF SOLUTION CHEMISTRY
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2020
·Vol. 49
·期 2
·145-165
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IF 1.273
Yang Xuzhao,Wang Jun,Fang Yun
Asymmetrical ammonium-based gemini ionic liquids, 1-trimethylammonium-3-(1-methylpiperidinium)propane dibis[(trifluoromethyl)sulfonyl]imide ([N 111 C 3 MPip][NTf 2 ] 2 ) and 1-trimethylammonium-3-(4-methylmorpholinium)propane dibis[(trifluoromethyl)sulfonyl]imide ([N 111 C 3 MMor][NTf 2 ] 2 ), were synthesized and structurally characterized by 1 H NMR, 13 C NMR, and MS. The melting temperatures and associated enthalpies and entropies of fusion of these gemini ionic liquids have been determined through differential scanning calorimetry (DSC). Thermal stabilities of [N 111 C 3 MPip][NTf 2 ] 2 and [N 111 C 3 MMor][NTf 2 ] 2 have been investigated by thermogravimetric analysis technology under pure nitrogen atmosphere. The solubility data of [N 111 C 3 MPip][NTf 2 ] 2 and [N 111 C 3 MMor][NTf 2 ] 2 in water, ethanol, benzyl alcohol, 2-phenylethanol and n -heptane were determined by a synthetic method using a laser monitoring observation technique in the temperature range 298.15–333.15 K under atmospheric pressure. The solubility in all pure solvents increased with the increasing temperature and the greatest solubilities of both gemini ionic liquids were observed in benzyl alcohol. The modified Apelblat, Buchowski–Ksiazaczak λh and NRTL models were employed to correlate the experimental solubility data. The calculated results show good agreement with the experimental data and modified Apelblat and λh equations are more accurate than the NRTL model. The standard state enthalpy, entropy, and Gibbs energy of dissolution of the GILs in the studied solvents were evaluated through the van′t Hoff equation using the experimental solubility data. The excess enthalpies of the solutions were also determined by the λh model. The dissolution behavior can serve for the synthesis and purification process of GILs.
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CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Suhang Chen,Hongsheng Yu,Wei Zhang,Ruiqi Shen,Wei Guo,Luigi T. DeLuca,Haiyang Wang,Yinghua Ye
The aluminum-fluorine reaction hold great potential in crippling Al pre-combustion sintering and agglomeration during combustion. Herein, the laser-sensitive Al/PVDF fuel rich films were prepared by employing a sponge-like microvoids structure through a phase inversion method coupled with micro-segmented flow, displaying the laser power threshold and ignition delay time by less than 4.8 J·cm −2 and 1.57 ms compared to unignited dense Al/PVDF pellet by a 19.6 J·cm −2 laser. The decreased Al atoms plasma electron temperature and a reduced F irons density with the increased Al content, imply a reduction of Al-F reaction ratio. This Al/PVDF films reveal 5 times higher flame propagation rate and mass consumption compared to the vacuum freeze-dried one, contributing to enhanced convective heat transfer in sponge-like microvoids channels. The ambient oxygen and released HF diffusion in microvoids, creating Al-F, Al-O competitive reaction path. The Al-O and Al-F reactions proportions of Al-30, Al-50 and Al-70 in open air were determined by 2:98, 41:59 and 74.5:22 after inferring evaporated AlF 3 combustion products and O 2 reactant by several assumption and calculation based on XPS results. The released gaseous H 2 and AlF 3 from Al droplet surface reduce nano-aluminum sintering. The different reaction paths of Al/PVDF films during combustion and thermal analysis were analyzed.
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FUEL
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2020
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IF 5.578
Huimin Chen,Fengjiao Yi,Caiping Ma,Xiang Gao,Suyao Liu,Zhichao Tao,Baoshan Wu,Hongwei Xiang,Yong Yang,Yong-wang Li
The bifunctional catalysts capable of regulating the metal dispersion and location through encapsulating palladium (Pd) nanoparticles inside Beta and mordenite (MOR) zeolites were used for n-heptane hydroisomerization. Several characterizations such as X-ray powder diffraction (XRD), scanning electron microscope (SEM), N 2 -adsorption and so on suggested that the difference in the phase, textural property, morphology, and acidity of zeolites between the catalysts with encapsulation structure and prepared by impregnation method was negligible whether Beta- or MOR-series catalysts. Nevertheless, the higher Pd dispersion, smaller Pd particle size, and higher aggregation resistance can be achieved on the encapsulation catalysts as determined by H 2 -pulse and transmission electron microscopy (TEM). Compared to the palladium-loading catalyst prepared by conventional impregnation method, the encapsulation structure guaranteed the higher selectivity and yield in n-heptane isomerization due to the significantly improved balance and intimacy. Furthermore, the catalyst with the complete encapsulation structure for the Beta-series catalysts and the catalyst with partial encapsulation structure for the MOR-series catalysts respectively exhibited the highest isomer selectivity and yield. All results may be resulted from that the zeolite topology and crystal size acted a significant role in determining the intimacy of the bifunctional catalysts with encapsulation structure, due to the different diffusion hurdles of the channels structure.
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高影响因子
CELLULOSE
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2020
·Vol. 27
·期 12
·7283-7296
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IF 4.21
Lu Ruiyang,Yu Yucong,Adkhamjon Gafurov,Gong Wenli,Sun Xiaoqing,Liu Lin
Abstract In this paper, a facile and efficient approach to robust and durable superhydrophobic cotton fabric was presented via in situ CuO deposition and stearic acid (STA) coating. The combined effects of both rough structure and low surface energy endowed cotton fabric (Cot) with superhydrophobicity, water repellency, and self-cleaning property. Moreover, the as-prepared fabric (Cot–CuO–STA) could keep its robust superhydrophobicity under harsh environmental conditions of acidic, alkaline and salt solutions, high temperature, mechanical abrasion and washing. Importantly, the obtained Cot–CuO–STA with WCA of 156.5° had great potential in oil/water separation with high separation efficiency of up to 98.7% for various oils (dichloromethane, trichloromethane, soybean oil, and n-heptane). Further, fascinating permeate flux (more than 1800 L.m −2 .h −1 ) and remarkable recyclability made Cot–CuO–STA a promising application in oil-contaminated water treatment and marine spilt oil cleanup. Graphic abstract Robust and durable superhydrophobic cotton fabric was fabricated for oil/water separation via a facile and efficient route. The resultant fabric exhibited remarkable separation efficiency for different kinds of oils, fascinating permeate flux, and excellent recyclability.
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Molecular Catalysis
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2020
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IF 3.687
Yepeng Xiao,Jincheng Liu,Hui Wang,Chong Yang,Huicheng Cheng,Yiqiang Deng,Lihua Cheng,Yanxiong Fang
Designing high-performance catalyst for the oxidation of cyclohexane (CyH) into value-added products like cyclohexanol and cyclohexanone (the mixture called KA oil) is of paramount significance in chemical industry. Herein, the catalytic activity of graphene oxide coupled with Ag and Fe 3 O 4 nanopaticles composites (GO-Ag&Fe 3 O 4 NPs) was investigated to understand the synergistic effect between Ag and Fe 3 O 4 NPs in photothermal oxidation of CyH. The comparative experiments between thermal and photothermal catalysis indicated that: (a) Conversion efficiency was facilitated by temperature rise, but less than 50 % of selectivity to KA oil was obtained at high temperature (140 °C); (b) Higher selectivity and milder condition were achieved by photothermal catalysis comparing to that of the thermal catalysis; (c) Ag NPs played more important role in photocatalysis, while thermocatalysis was intensified by Fe 3 O 4 NPs. Using 1.5 MPa of dry air as oxidant, 6.6 % of CyH conversion with over 98 % of selectivity was gained by GO-Ag&Fe 3 O 4 NPs. Additionally, no obvious decline in catalytic efficiency was observed after 5 cycles. The concept of photothermal cooperation for CyH oxidation over GO-Ag&Fe 3 O 4 NPs may provide a new approach for the partial oxidation of saturated C H and the design of high-performance catalysts.
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FOOD CHEMISTRY
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2020
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IF 6.306
Xiujuan Wang,Meng Song,Suting Liu,Sizhu Wu,Aung Myat Thu
Based on the experimental data of gas chromatography-mass spectrometry, an improved artificial neural network was first established to predict the migration of 2-ethylhexyl phthalate (DEHP) plasticizer from poly(vinylidene chloride) (PVDC) into food simulants (ie., heptane, ethanol and water). The sensitivity analysis indicated that temperature acted as a crucial factor influencing the migration values of DEHP. Then, a combined experimental and molecular dynamic (MD) simulation was performed to understand the migration kinetics and the mechanism of DEHP. Hansen solubility parameters of three component ( δ d , δ p , δ h ) were simplified into two-component solubility parameters ( δ vdW , δ e ), and the tuple was successfully applied to describe the interactions between PVDC and food simulants. The MD results showed that high interaction energy and fractional free volume in PVDC/DEHP/food simulant systems accelerated the migration of DEHP. These fundamental studies would provide significant insights into the migration of environmental contaminants.
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PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
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2020
·Vol. 44
·期 25
·10621-10627
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IF 3.288
Xue Xiong,Meiling Qi
This work presents a novel column fabrication approach for capillary gas chromatography (CGC) through the condensation reaction of a hydroxyl-terminated polymer with a cross-linker inside a capillary column. In this work, polypropylene glycol (PPG 4000) and tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS) were employed to fabricate the PPG-gel capillary column for GC analyses. Inside the column, a 3D cross-linked organogel network forms on the capillary inner surface by condensation of PPG 4000 with ICS under the given mild conditions. As a result, the PPG-gel column exhibited moderate polarity and showed distinctly advantageous resolving performance and inertness for carboxylic acids over the PPG column by the conventional static coating method. Also, it achieved high-resolution separations of the isomer mixtures of alkanes, alkylbenzenes and halobenzenes. Moreover, the PPG-gel column exhibited dramatically improved solvent stability because of its cross-linked organogel network. The organogel column displayed excellent column repeatability and reproducibility with the RSD% values in the range of 0.01–0.04% for run-to-run, 0.71–0.84% for day-to-day and 2.4–3.1% for column-to-column. The proposed organogel approach is facile and applicable to other analogous materials and has a promising future for wide applications.
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JOURNAL OF MEMBRANE SCIENCE
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2020
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IF 7.183
Xiaochang Cao,Haoqing Xu,Songlin Dong,Jiayou Xu,Zhihua Qiao,Song Zhao,Jixiao Wang,Zhi Wang
In this work, we proposed a simple method to prepare high-performance and pressure-resistant mixed matrix membranes (MMMs) for CO 2 /H 2 separation. The groups or segments of poly-(vinylamine) (PVAm) were used to modify covalent organic frameworks (COFs), and COFs with similar frameworks but different surfaces were obtained. Then, modified COFs were mixed with PVAm matrix and used to coat the modified-polysulfone (mPSf) to prepare MMMs for CO 2 /H 2 separation. Modified COFs and the PVAm matrix were highly compatible because COF surfaces possessed the same groups or segments as PVAm. Meanwhile, in the coating solution, COF surfaces were found to induce penetration of PVAm molecules into COF pores, narrowing the pore size of the COFs and providing an amino environment for CO 2 preferential absorption and transport. The penetration degree was affected by the hydrogen bond between COF surfaces and the PVAm molecules. In addition, the incorporated COFs effectively restricted the mobility of the PVAm matrix, increasing the pressure resistance for MMMs under high pressure. In the gas permeation test, the optimal MMMs could achieve a CO 2 permeance of 957 GPU and a CO 2 /H 2 selectivity of 17.1 at 2.0 MPa because of the high compatibility and size of the channels (0.94 nm).
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