JOURNAL OF CHROMATOGRAPHY A
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2020
·
IF 4.049
Qianqian Xu,Baogen Su,Zongbi Bao,Yiwen Yang,Qiwei Yang,Qilong Ren
Gas-liquid chromatography is an effective method to determine infinite dilution activity coefficients ( γ ∞ ). Wall-coated open-tubular (WCOT) column which offers more advantages over packed column should be a preferable column type; however, the small carrier gas flow rate and stationary phase amount in WCOT columns limit its application in the determination of γ ∞ . Mathematical strategy made some progress to avoid the quantification problem in the determination of γ ∞ by static-wall-coated open-tubular (SWCOT) columns. However, the previously reported strategy was based on the assumption that SWCOT column was geometrically an ideal hollow cylinder, which indeed deviates from the reality. In this study, without that assumption, we derived a new microgeometry-independent equation by using the relationship between the hold-up volume ( V M ) and the volume of stationary phase ( V L ), and used it to measure the γ ∞ of various organic solutes in two ionic liquids (ILs) 1‑butyl‑3-methylimidazolium dicyanamide and 1,3-dibutyronitrile-imidazolium bis((trifluoromethyl)sulfonyl)imide, both of which contain double cyano groups in the anion or cation. Phase loading study was adopted to eliminate the influence of interfacial adsorption to partition. The infinite dilution partial molar excess enthalpy, selectivity and capacity were directly calculated from the experimental γ ∞ values, and the linear solvation energy relationship (LSER) model was used to characterize the specific properties of both ILs. This new established equation will promote the application of SWCOT columns in thermodynamic measurement and benefit the fast screening of novel solvents for chemical separation processes.
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Catalysts
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2020
·Vol. 10
·期 5
·533
·
IF 3.52
Jinjun Wen,Chunlei Huang,Yuhai Sun,Long Liang,Yudong Zhang,Yujun Zhang,Mingli Fu,Junliang Wu,Limin Chen,Daiqi Ye
CO2hydrogenation to methanol is one of the main and valuable catalytic reactions applied on Cu/ZnO-based catalysts; the interface formed through Zn migration from ZnO support to the surface of Cu nanoparticle (ZnOx-Cu NP-ZnO) has been reported to account for methanol synthesis from CO2hydrogenation. However, the accompanied reverse water gas shift (RWGS) reaction significantly decreases methanol selectivity and deactivates catalysts soon. Inhibition of RWGS is thus of great importance to afford high yield of methanol. The clear understanding of the reactivity of RWGS reaction on both the direct contact Cu-ZnO interface and ZnOx-Cu NP-ZnO interface is essential to reveal the low methanol selectivity in CO2hydrogenation to methanol and look for efficient catalysts for RWGS reaction. Cu doped plate ZnO (ZnO:XCu) model catalysts were prepared through a hydrothermal method to simulate direct contact Cu-ZnO interface and plate ZnO supported 1 wt % Cu (1Cu/ZnO) catalyst was prepared by wet impregnation for comparison in RWGS reaction. Electron paramagnetic resonance (EPR), XRD, SEM, Raman, hydrogen temperature-programmed reduction (H2-TPR) and CO2temperature-programmed desorption (CO2-TPD) were employed to characterize these catalysts. The characterization results confirmed that Cu incorporated into ZnO lattice and finally formed direct contact Cu-ZnO interface after H2reduction. The catalytic performance revealed that direct contact Cu-ZnO interface displays inferior RWGS reaction reactivity at reaction temperature lower than 500 °C, compared with the ZnOx-Cu NP-ZnO interface; however, it is more stable at reaction temperature higher than 500 °C, enables ZnO:XCu model catalysts superior catalytic activity to that of 1Cu/ZnO. This finding will facilitate the designing of robust and efficient catalysts for both CO2hydrogenation to methanol and RWGS reactions.Keywords:reverse water–gas shift reaction;CO2hydrogenation to methanol;Cu doping;direct contact Cu-ZnO interface;ZnOx-Cu NP-ZnO interface
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2020
·
IF 5.774
Xiao Li,Shifan Yu,Kun Li,Chao Ma,Jing Zhang,Hui Li,Xiao Chang,Lei Zhu,Qingzhong Xue
It is imperative to research CO 2 separation membrane in terms of the issues of greenhouse gas emission. In this work, zeolitic imidazolate frameworks-8 (ZIF-8) particles in situ inserted by multiwalled carbon tubes (MWCNTs) (MWCNTs@ZIF-8) were embedded into Pebax matrix to fabricate mixed matrix membranes (MMMs). The incorporated ZIF-8 particles increased the free volume of membranes, resulting in the improvement of the CO 2 permeability. The functionalized MWCNTs in situ inserted into ZIF-8 particles not only avoided the aggregation of ZIF-8 particles but also enhanced the CO 2 adsorption property, resulting in the improvement of the CO 2 /N 2 selectivity. Furthermore, the MWCNTs can provide rapid transport channels for CO 2 molecules between two adjacent ZIF-8 particles and high mechanical properties for membranes. As a result, the MMMs with 8 wt% MWCNTs@ZIF-8 exhibited an excellent separation performance with CO 2 permeability of 186.3 Barrer and CO 2 /N 2 selectivity of 61.3, which surpassed the 2008 Robeson upper-bound. This study provided a new strategy for preparing high-performance CO 2 separation membranes.
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FUEL PROCESSING TECHNOLOGY
·
2020
·
IF 4.982
Yue Cao,Bing Song,Min Song,Fanyue Meng,Yuexing Wei,Qi Cao
Arsenic with high volatility and toxicity is usually generated during coal combustion and the capture of arsenic is restrained at high temperature since the sintering of adsorbents. Therefore, it is necessary to develop an adsorbent with sintering resistance for the arsenic removal at high temperature. In the study, the arsenic vapor capture by CaSiO 3 , CaO and SiO 2 was carried out in the flue gas with/without SO 2 and NO at high temperatures from 1000 °C to 1200 °C. The results showed that CaSiO 3 exhibited excellent arsenic capture with the capacity of 4.98 mg/g and the capture efficiency was increased with the temperature increasing. The effect of acid gases was also considered. A certain amount of CaSO 4 with poor capture performance was formed on CaSiO 3 surface in the presence of SO 2 , leading to the decrease of the amount of arsenic captured. On the other hand, the effect of NO was not obvious as SO 2 . Although arsenic capture was suppressed when introduced SO 2 and NO, it still remained considerable arsenic capture for the CaSiO 3 adsorbent. Additionally, the pivotal role of O 2 was also studied. Taking into account the high capture capacity and excellent anti-sintering property, CaSiO 3 was a good adsorbent suitable for the removal of arsenic from coal combustion flue gas.
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RSC Advances
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2020
·Vol. 10
·期 50
·29843-29854
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IF 3.119
Wenwen Zeng,Yingzhi Liu,Guoliang Chen,Haoran Zhan,Jun Mei,Nan Luo,Zhoukun He,Changyu Tang
Considering the harmfulness of nitrogen dioxide (NO2), it is important to develop NO2 sensors with high responses and low limits of detection. In this study, we synthesize a novel SnO–Sn3O4 heterostructure through a one-step solvothermal method, which is used for the first time as an NO2 sensor. The material exhibits three-dimensional flower-like microparticles assembled by two-dimensional nanosheets, in situ-formed SnO–Sn3O4 heterostructures, and large specific surface area. Gas sensing measurements show that the responses of the SnO–Sn3O4 heterostructure to 500 ppb NO2 are as high as 657.4 and 63.4 while its limits of detection are as low as 2.5 and 10 parts per billion at 75 °C and ambient temperature, respectively. In addition, the SnO–Sn3O4 heterostructure has an excellent selectivity to NO2, even if exposed to mixture gases containing interferential part with high concentration. The superior sensing properties can be attributed to the in situ formation of SnO–Sn3O4 p–n heterojunctions and large specific surface area. Therefore, the SnO–Sn3O4 heterostructure having excellent NO2 sensing performances is very promising for applications as an NO2 sensor or alarm operated at a low operating temperature.
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ANALYTICA CHIMICA ACTA
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2020
·
IF 5.977
Zhuoru He,Qing Luo,Zhongqiu Liu,Lingzhi Gong
GC-MS platform has been proved to be an important analytical technique for plasma metabolomics , but lack of efficient sample preparation strategies prior to sample injection has limited its wide application. In the present work, twenty two extraction protocols including protein precipitation (PPT), liquid-liquid extraction (LLE), solid-phase extraction (SPE) and ultrafiltration were simultaneously evaluated using non-spiked and metabolite standards spiked human plasma. Sample-to-extraction solvent ratio and metabolites derivatization conditions were also investigated and optimised. The results demonstrated that stepwise LLE protocol (MeOH–H 2 O/CHCl 3 /CHCl 3 –MeOH) was the most efficient extraction strategy for the combination of untargeted and targeted metabolomics. Sample-to-extraction solvent ratio of 1:3 (v:v) was found to perform better than higher solvent ratios. Also, the maximum derivatization performance was obtained when using 30 μL N-methyl-N-tri-methylsilyltrifluoroacetamide (MSTFA) and 1% trimethyl-chlorosilane (TMCS) incubated at 60 °C for 120 min. In the end, the optimised sample preparation method was applied successfully to plasma untargeted metabolomics of rheumatoid arthritis (RA) and four metabolites (gamma-butyrolactone, MG (0:0/18:0/0:0), tocopherol and oxalic acid) were found to be potential biomarkers for the diagnosis of RA.
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Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 26
·13132-13141
·
IF 11.301
Yang Feng,Zhikun Wang,Weidong Fan,Zixi Kang,Shou Feng,Lili Fan,Songqing Hu,Daofeng Sun
The designability and adjustability of the pore structure are vital advantages of metal–organic framework (MOF) materials for separation. Their exploration in the field of membrane separation is still inadequate, especially for the regulation of the pore environment based on the inorganic secondary building unit (SBU). In this work, we have studied the effect of the pore environment regulated by the SBU on the gas separation performance of MOF membranes for the first time. The Fe3(μ3-O)(CH3COO)6 SBU of the parent framework (soc-MOF, a stable microporous Fe-MOF) was in situ modified with imidazole (IM) molecules to construct the soc-MOF-IM polycrystalline membrane. The exact location of the incorporated IM and the narrowed pore size are observed based on the determined crystal structure. The gas solubility, diffusivity and separation performance of the two membranes are evaluated. Compared to the soc-MOF membrane with a H2/CO2 selectivity of 6, the soc-MOF-IM polycrystalline membrane possesses a significantly enhanced H2/CO2 selectivity (48), which is mainly attributed to the triggered molecular sieving effect. Thanks to the facile introduction of functional molecules and precise adjustment of the pore environment, SBU modification can be a powerful strategy to improve the separation performance of MOF membranes.
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CELLULOSE
·
2020
·Vol. 27
·期 12
·7127-7138
·
IF 4.21
Liu Hanbin,Yang Xiaohan,Wang Jiaxi,Meng Qingjun,Qian Liwei,Wu Haiwei,Duan Chao,Li Zhijian,Zhou Hongwei
Abstract Separation of dyes and proteins from water remains a significant challenge. Common absorbents without recyclability might bring secondary pollutions, which may be avoided by developing stimuli-responsive smart absorbents. Here in this work, a CO 2 -responsive polymer poly(2-(dimethylamino) ethyl methacrylate) was grafted from cellulose fibers (Cell-g-PDEA). The chemical structure and surface morphology were confirmed with nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction and scanning electron microscope. The CO 2 -sensitivity was demonstrated by monitoring the pH, surface Zeta potential and dispersed appearance under stimulus of CO 2 . Furthermore, the modified cellulose fibers were packed into a syringe to construct a smart separation column that reversibly captured and released anionic dyes and proteins from water under gas stimulus. Comparing with traditional pH or temperature responsive materials, the CO 2 -responsive cellulose fibers take the advantages on energy-saving, good reversibility and moderate running conditions, thus might find applications in smart separations, clinical diagnose and therapies. Graphic abstract
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 25
·10621-10627
·
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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Materials
·
2020
·Vol. 13
·期 9
·2033
·
IF 3.057
Yongzhen Lei,Long Mao,Jin Yao,Zhihan Li
Poly(lactic acid) (PLA) represents one of the most promising and attractive bio-based polymers for green packaging. However, toughness, gas barrier and antibacterial properties of pure PLA films cannot compete with those of traditional petroleum-based active packaging plastics. To fill this gap, utilization of excellent chelating properties of phytic acid (PA), functionalized layered double hydroxides (LDHs@PA-Cu(II)) was firstly synthetized via facile deposition and chelation of one-step assembled PA-Cu(II) coordination compounds on the surface of layered clay. Furthermore, LDHs@PA-Cu(II)/PLA nanocomposites were prepared by blending LDHs@PA-Cu(II) and pure PLA via solution casting evaporation process. After adding only 1 wt % LDHs@PA-Cu(II), elongation at break and tensile strength increase by 53.0% and 18.9%, respectively, and the oxygen relative permeability decreases by 28.0%. Due to the strong interface interaction and heterogenous nucleation, the reinforcement effect of LDHs@PA-Cu(II) at low loadings is remarkable. Meanwhile, owing to the antibacterial activity of PA-Cu(II) coatings, the antibacterial rate (against Escherichia coli) of LDHs@PA-Cu(II) exceeds 99.99%. Furthermore, the corresponding LDHs@PA-Cu(II)/PLA nanocomposites also show outstanding antibacterial properties, which will be a promising candidate for active packaging application.Keywords:layered double hydroxides;phytic acid;antibacterial activity;polylactic acid;barrier properties
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CRYSTENGCOMM
·
2019
·Vol. 22
·期 2
·275-282
·
IF 3.382
Peng Yan,Jucai Yang,Xiangying Hao,Zhisheng Chen,Guanhua Shen,Yanhua Zhao,Deyun Ma,Jiaxin Zhu
A new Zn-based metal–organic framework with 8-connected hex topology constructed from bipyridine and carboxylate ligands, namely [Zn(cpna)3(tmbpy)]n·4DMF (1) (H2cpna = 6-(4-carboxyphenyl)nicotinic acid; tmbpy = 3,3′-dimethyl-4,4′-bipyridine), has been synthesized under solvothermal conditions. The Zn-MOF was structurally characterized and retained a good crystal structure after activation (1a), an indication of permanent porosity. 1a exhibits a BET surface of 770 m2 g−1 and the maximum aperture of 8.60 Å. Single component adsorption isotherm measurements of C2H2, CO2, CH4, CO and N2 on 1a were performed both at 273 K and 298 K, and the selectivities for C2H2/CH4, C2H2/CO2, CO2/CO, CO2/CH4 and CO2/N2 were estimated on the basis of the ideal adsorbed solution theory (IAST). 1a shows the uptake of C2H2 (3.89 mmol g−1) and CO2 (3.52 mmol g−1) at 273 K and 100 kPa, respectively. Due to the Lewis basic pyridyl sites inside the channel of the framework, 1a showed good adsorption selectivities for C2H2/CH4(50 : 50) and C2H2/CO2(50 : 50) at 298 K (100 kPa).
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CRYSTENGCOMM
·
2019
·Vol. 21
·期 42
·6414-6422
·
IF 3.382
Rui Zhang,Wanqing Song,Mingjing Wang,Huiming Ji
Metal–organic framework (MOF) materials with controlled microstructures have become popular in the last few decades. In this study, Zn-MOF precursors with diverse crystallinity and particle size (20–800 nm) were synthesized using an accelerating or retarding nucleation process by introducing various secondary ligands, which were employed as modulators in the coordination and ligand exchange equilibria according to their different acidity coefficients. Thus, the pore size of MOF-derived ZnO clusters was different, resulting in diverse gas sensing properties. Moreover, large precursor-derived ZnO-(2 and 3) assemblies with the micropore sizes of 1 nm and 0.75 nm showed size-selective sensing and better performance, which exhibited a higher and fast response (4 s) to butanone and n-butanol with the lengths of 0.664 nm and 0.499 nm, respectively, and a low limit of detection (0.1 ppm). This simple method of controlling the nucleation of MOFs and the pore size of ZnO assemblies paved a new way towards the design of the microstructure of MOF-based functional materials.
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