CHIRALITY
·
2019
·Vol. 31
·期 12
·1053-1059
·
IF 1.927
Yu-Yu He,Jun-Hui Zhang,Qing Pu,Sheng-Ming Xie,Yan-Xia Li,Lan Luo,Xue-Xian Chen,Li-Ming Yuan
Chiral mesoporous silica (CMS) has attracted widespread attention because of some unique properties, such as high surface area, uniformly structured nanoscale cavities, and excellent chemical and thermal stability. In this work, we report the utilization of a CMS as the stationary phase for the separation of racemates in gas chromatography (GC). A CMS-coated capillary column was fabricated by a dynamic coating method. Eighteen racemates belonging to different classes of organic compounds were separated on this column, including chiral alcohols, aldehydes, ketones, organic acids, halohydrocarbons, alkenes, alcohol amines, epoxides, and amino acid derivatives. In addition, linear alkanes, alcohols, and aromatic hydrocarbons have also been resolved.
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GREEN CHEMISTRY
·
2019
·Vol. 22
·期 3
·742-752
·
IF 9.405
Xiwei Hu,Xun Sun,Qiang Song,Yangyang Zhu,Yu Long,Zhengping Dong
Metal-free carbon catalysts with excellent catalytic performance have drawn much research attention recently. Herein, polymer-derived N,S co-doped carbon catalysts (PDNSC-X) with a hierarchically porous structure were facilely prepared by a cost-effective and convenient strategy via carbonization of a N- and S atom-containing polymer precursor and were subsequently used as efficient metal-free catalysts. The catalytic activity of the as-fabricated PDNSC-800 was greater than those of other reported heteroatom-doped carbon catalysts in catalytic reduction of various nitroarenes. The high catalytic activity of PDNSC-800 was related to the synergistic effects of a high surface area, a hierarchically porous structure, abundant N- and S-containing active sites, and defect formation. In addition, the close relationship between the N species (especially pyrrolic N) and high selectivity in metal-free catalytic synthesis was investigated in the reduction of nitroarenes and selective oxidation of ethylbenzene. This study may provide a new strategy to fabricate specific heteroatom-doped metal-free carbon catalysts for environmentally friendly efficient organic transformation.
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MICROCHIMICA ACTA
·
2019
·Vol. 187
·期 1
·1-8
·
IF 5.479
Xi Ying,Du Yingxiang,Sun Xiaodong,Zhao Shiyuan,Feng Zijie,Chen Cheng,Ding Wen
A monolithic capillary column was prepared by single-step copolymerization of the ionic liquid 1-vinyl-3-octylimidazolium bromide (VOI) and styrene. The VOI and styrene monomers were introduced to provide multiple interaction sites and increase hydrophobicity and aromaticity of the monolithic column, respectively. The effect of porogen ratio, monomer ratio and reaction temperature on permeability was investigated. The resulting column was characterized by scanning electron microscopy, and the results suggest that the column possesses high porosity and good homogeneity. A relatively strong anodic electroosmotic flow was generated over a wide range of pH values (pH 2.0–10.0), and this facilitates the rapid separation of analytes within 12 min. Alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), proteins and amino acids were used to evaluate the performance of the monolithic column under capillary electrochromatography mode by UV detection. Mixed-mode retention mechanisms including hydrophobic interaction, π-stacking, ion-exclusion interaction were observed. The monolithic column exhibits high column efficiency (8.72 × 10 4 plates∙m −1 ) and satisfying separation capability (the resolution of four alkylbenzenes: 2.54, 2.86 and 4.62, four PAHs: 2.79, 4.83 and 4.77, three proteins: 4.35 and 2.86, two amino acids: 3.34).
Schematic representation of capillary electrochromatography (CEC) systems with ionic liquid and styrene based organic polymer monolithic column for separation of alkylbenzenes, polycyclic aromatic hydrocarbons, proteins and amino acids.
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BUILDING AND ENVIRONMENT
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2019
·
IF 4.82
Shen Yang,Xudong Yang,Dusan Licina
People spend a substantial amount of daily time in vehicle environments being exposed to variety of airborne chemicals. High concentrations of volatile organic compounds (VOCs) inside vehicle cabins have been of increasing concern owing to various health risks. Yet, there is a limited knowledge and data about VOC emissions from interior vehicular materials. In a controlled small-scale ventilated chamber, we quantified dynamic VOC emission characteristics for four commonly-used vehicular interior materials (leather coat of seats (LCS), dashboard (DB), pillar (PI) and ceiling (CE)) exposed to the two interior air temperatures (25 and 60 °C). The emission strengths of VOCs increased with temperature elevation by 3–36 times, but not linearly for every group of compounds. The level of individual VOC compounds emitted was a strong function of time, indicating the importance of a continuous sampling approach. Correlation analysis of individual VOCs revealed different emission mechanisms among the major compounds. The source apportionment results indicated that the LCS materials were associated with emissions of aromatics, carbonyls and other VOCs at 25 °C, while special attentions should be paid to the DB and the PI for their predominant contributions to extremely elevated level of aliphatic compounds at 60 °C. The results of this study are potentially useful for database of VOC emissions from vehicular materials, development of improved standard testing methods and for improved modeling of VOC emissions.
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NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 44
·17306-17314
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IF 3.069
An Pei,Luna Ruan,Jianhua Liao,Huan Zhang,Jiexiang Wang,Kai Yang,Zhiping Liu,Lihua Zhu,Bing Hui Chen
Herein, Ni/C was prepared at room temperature (RT) by liquid chemical reduction by using hydrazine hydrate as the reducing agent. The impregnation method was adopted to deposit precious metals on carbon black (C) to obtain the Pd/C, Ru/C monometallic and PdRu/C bimetallic catalysts. The PdNi/C, RuNi/C bimetallic and PdRuNi/C tri-metallic catalysts were obtained through a chemical replacement reaction method. The as-prepared catalysts were characterized by inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), high-angle annular dark-field scanning TEM (HAADF-STEM) and STEM energy dispersive X-ray spectroscopy (STEM-EDS) elemental mapping and line-scanning, scanning electron microscopy (SEM) and SEM-EDS, X-ray photoelectron spectroscopy (XPS) and high-sensitivity low-energy ion scattering spectroscopy (HS-LEIS) techniques, which proved that PdRu islands were supported on the Ni/Ni(OH)2 nanoparticles (NPs) (PdRu-on-Ni/Ni(OH)2 NPs) in PdRuNi/C. The results revealed that the PdRuNi/C catalyst showed the most excellent catalytic performance for ethylbenzene hydrogenation under mild reaction conditions mainly owing to the synergistic effect among the Pd, Ru and Ni related species. The PdRuNi/C catalyst also exhibited good stability in ethylbenzene hydrogenation.
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JOURNAL OF CHROMATOGRAPHY A
·
2019
·
IF 3.858
Zhihua Song,Shenghong Li,Yafeng Guan,Shuo Wang,Yinghao Wang,Gangqiang Yang,Xiaochen Zhang,Jinhua Li,Wenhao Song,Chuanming Zhou,Lingxin Chen
In this work, multilayer zirconia-coated silica (ZrO 2 /SiO 2 -n) microspheres were successfully produced by a straightforward hydrothermal procedure with a low concentration of Zr 4+ (5 mM) under low potential of hydrogen (pH) conditions (pH = =2). The obtained ZrO 2 /SiO 2 -n materials exhibited favorable characteristics for high-performance liquid chromatography (HPLC) separation, including high surface area and pore volume, good pore structure, narrow particle size, and pore size distribution. In addition, the zirconia coverage in the mesopores was confirmed by soaking the material in 1 M NaOH solution, with the particles showing strong resistance to the basic solution. The obtained ZrO 2 /SiO 2 -n stationary phases were packed into a fused-silica capillary tubing for the separation of alkaloids in hydrophilic interaction chromatography (HILIC) mode, and a column efficiency of 47,800 plates/m was obtained for berberine on a ZrO 2 /SiO 2 -6 micro column. The ZrO 2 /SiO 2 -6 microspheres were further modified by dodecylphosphonic acid (C 12 P-2-ZrO 2 /SiO 2 -6); the C 12 P-2-ZrO 2 /SiO 2 -6 material showed great potential for application in reversed-phase liquid chromatography (RPLC) mode. The C 12 P-2-ZrO 2 /SiO 2 -6 micro column showed a column efficiency of 55,000 plates/m for naphthalene and 51,300 plates/m for benzene.
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SN Applied Sciences
·
2019
·Vol. 2
·期 1
·1-11
·
IF 0
Li Genrong,Yu Wenqin,Xiao Zhaojing,Long Mei,Tong Lanyan,Qiu Yue
A rapid, sensitive, and practical QuEChERS method coupled with gas chromatography–mass spectrometry was developed for the simultaneous determination of 16 chemical adjuvant residues in samples of fruits (apple, nectarine, grape) and vegetables (tomato, cucumber, spinach). All target compounds were separated in less than 16 min. Samples were extracted with acetonitrile, and the types of extraction salt and cleanup sorbent were optimized. The optimized method was validated by evaluating the linearity, accuracy, precision, and matrix effect. The recoveries of the 16 pesticides adjuvants ranged from 61.2 to 116.3% with relative standard deviations lower than 11.6%. Limits of detection ranged from 0.21 to 3.02 μg/kg, and limits of quantification ranged from 0.71 to 10.07 μg/kg. Finally, the developed method was successfully employed to identify and quantify pesticide adjuvant residues in the analysis of 30 real fruit and vegetable samples.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2018
·
IF 3.649
Heng Yu,Chao Fan,Yu Cheng,Benhua Huang,Yu Li,Junjie Zhang,Aqun Zheng,Yang Sun
A series of titanium-aluminum binary oxides are prepared through co-precipitation of metal salts with polyvinylpyrrolidone (PVP) in alkaline solution, along with dehydration. Most of synthetic oxides are composed of micro- or nano-sized blocks, while one of them shows an interesting two-dimensional morphology. Furthermore, loading of aluminum into co-precipitation would increase product porosity compared with the non-loaded case, while addition of PVP shows influences on building micropores of synthetic oxide. In catalysis, the synthetic oxides usually show high activities for nitration of various arenes. The key factors affecting catalytic outputs are carefully discussed, and the matching relation between shape of substrate and pore distribution of catalyst may affect catalytic efficiency too. Moreover, the binary oxide featuring PVP shows more durable recycling behavior than the non-doped one. On the other hand, nitration reactions of naphthalene and benzene halides show better stereoselectivities than those of alkylbenzenes. In general, this study may contribute to the catalytic progress of new oxide materials.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 2
·1-8
·
IF 5.479
Li Zhentao,Mao Zhenkun,Chen Zilin
This work reports on the in-situ growth of a metal organic framework (MOF) composed of zinc(II), adeninate and biphenyldicarboxylate on the inner wall of a capillary, and the use of this MOF as a stationary phases in open-tubular capillary electrochromatography. The inner wall of a fused-silica capillary was first modified with 3-aminopropyltriethoxysilane to create surface amino sites, and then the MOF was synthesized by in-situ growth. The modified capillary was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results proved the successful growth of the MOF. The resultant open-tubular column showed good separation selectivity towards neutral compounds, acidic and basic compounds including nonsteroidal anti-inflammatory drugs, sulfa drugs and small biomolecules. In addition, the modified column is stable and repeatable. The precisions (expressed as RSDs) of the retention time for intra-day ( n = 5) and inter-day (n = 5) separations and between columns ( n = 3) are less than 0.5, 1.6 and 4.7%, respectively. Conceivably, this new kind of MOF represents a most useful novel stationary phase in electrochromatographic separations.
Schematic presentation of the open-tubular column modified with bio-MOF-1 by in situ hydrothermal reaction with adeninate, Zn(II) and biphenyldicarboxylate for capillary electrochromatographic separations.
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TALANTA
·
2018
·
IF 4.244
Tiemei Li,Yuefei Song,Jingjie Xu,Jing Fan
As a new type of green solvents , deep eutectic solvents (DESs) are attracting more and more attentions due to their unique properties and cheapness. However, most DESs reported previously were hydrophilic and thus limiting their applications in aqueous medium. In this study, a novel hydrophobic DES was prepared by mixing ethylparaben and methyl trioctyl ammonium chloride , and density, viscosity, and contact angle of the DES were determined to character its solvent characteristics. Then, this DES was used as an efficient additive of sol-gel sorbent coating of poly(dimethylsiloxane) (PDMS) fiber. It was found that the addition of hydrophobic DES could generate a lot of neat pores in the PDMS fiber surface, thus significantly improving the performance of PDMS fiber coating. The feasibility of PDMS-DES adopted for head space solid phase microextraction was evaluated by GC-FID for the extraction and determination of volatile organic compounds, such as toluene, ethylbenzene and o -xylene. Key parameters affecting the extraction efficiency were investigated systematically. Under optimal conditions, the linear range with PDMS-DES fiber lied between 10 and 1000 μg L −1 , and the limit of detection (LOD) was in the range from 0.005 to 0.025 μg L −1 . Compared with homemade PDMS fiber, the peak area of signal response for the PDMS-DES fiber was 3 times higher. At the same time, the LOD for the proposed method was much lower than the commercial 100 µm-PDMS fiber coating.
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Journal of Inorganic and Organometallic Polymers and Materials
·
2019
·Vol. 30
·期 3
·859-868
·
IF 1.637
Cheng Lingping,Cai Jianfeng,Ke Yanxiong
Core–shell particles (CSPs), also known as superficially porous particles or fused-core particles, consisting of a solid core and a porous shell, have emerged as an advanced technology in high-performance liquid chromatography (HPLC). We report here an ultrasonic-assisted sol–gel method for the fabrication of CSPs with uniform mesoporous silica shell using tetraethoxysilane as the silica source and dodecylamine as a catalyst, template and porogen agent in a methanol–water solution. Instead of stirring, sonication was adopted to guarantee the particles monodispersity and uniformity. The shell thickness between 300 and 700 nm could be obtained by adjusting the sonication time and the volume ratio of methanol–water. Pore sizes from 3.4 to 8.5 nm were tuned by hydrothermal treatment. The C18-bonded 2.7 μm CSPs with a shell thickness of ~ 500 nm showed some advantages over a commercial 1.7 μm BEH column, and successfully applied for the analyses of a Chinese medicine and peptides. The CSPs could be a promising candidate as HPLC packing materials.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2018
·
IF 2.196
Danxia Shen,Tao Chen,Peng Bai,Xianghai Guo
The isobaric vapor–liquid equilibrium (VLE) data for the binary systems 2-methoxyethanol + ethylbenzene, ethylbenzene + dimethyl sulfoxide (DMSO), and 2-methoxyethanol + DMSO and the ternary system 2-methoxyethanol + ethylbenzene + DMSO were measured with a Fischer VLE 602 apparatus at 100.00 kPa. The VLE data for all the binary and ternary systems were thermodynamically consistent and passed the Wisniak’s L–W test. The binary VLE data were correlated with the Wilson, nonrandom two-liquid, and universal quasichemical models with minor deviations. The ternary VLE data predicted from the corresponding binary interaction parameters agreed well with the experimental data. The azeotropic temperature and composition of the 2-methoxyethanol and ethylbenzene azeotropic mixture at 100.00 kPa were 391.05 K and 60.15 mol % 2-methoxyethanol, respectively. Additionally, the azeotrope disappeared after adding DMSO, which confirms that DMSO can serve as a prospective entrainer for separating 2-methoxyethanol from ethylbenzene in the extractive distillation process.
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