RSC Advances
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2017
·Vol. 7
·期 45
·28542-28547
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IF 3.108
Jie Hu,Yongjiao Sun,Xiu Wang,Lin Chen,Wengdong Zhang,Yong Chen
Flower-like molybdenum oxide@tungsten oxide (MoO3@WO3) composite microstructures were successfully synthesized by hydrothermal and impregnation methods. The fabricated samples were characterized by XRD, EDS, SEM and TEM, and the results show that the MoO3@WO3 composite is composed of crystallized nanosheets with a thickness of about 40 nm. The gas sensing properties of the MoO3@WO3 composite microstructures towards hydrogen sulfide (H2S) were investigated as a function of operating temperature and gas concentration. The gas sensors based on MoO3@WO3 composites show better sensing performances than that of a pure one. Moreover, the Mo6W-based gas sensor exhibits the highest response (28.5 towards 10 ppm H2S), fast response/recovery time (2 s/5 s), low detection limit (20 ppb) and good selectivity at optimum operating temperature (250 °C). Such an excellent performance can be attributed to the heterojunction between MoO3 and WO3.
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CHEMOSPHERE
·
2017
·
IF 4.208
Hongyun Hu,Dunkui Chen,Huan Liu,Yuhan Yang,Hexun Cai,Junhao Shen,Hong Yao
Arsenic emission from fuel combustion and metal smelting flue gas causes serious pollution. Addition of sorbents is a promising way for the arsenic capture from high temperature flue gas. However, it is difficult to remove arsenic from SO 2 /HCl-rich flue gas due to the competitive reaction of the sorbents with arsenic and these acid gases. To solve this problem, arsenic adsorption over γ-Al 2 O 3 was studied in this work to evaluate its adsorption mechanism, resistance to acid gases as well as regeneration behavior. The results show that γ-Al 2 O 3 had good resistance to acid gases and the arsenic adsorption by γ-Al 2 O 3 could be effectively carried out at a wide temperature range between 573 and 1023 K. Nevertheless, adsorption at higher-temperature (like 1173 K) leaded to the decrease of surface area and the rearrangement of crystal structure of γ-Al 2 O 3 , reducing the active sites for arsenic adsorption. The adsorption of arsenic was confirmed to occur at different active sites in γ-Al 2 O 3 by forming various adsorbed species. Increasing temperature facilitated arsenic transformation into more stable chemisorbed As 3+ and As 5+ which were difficult to remove through thermal treatment regeneration. Fortunately, the regeneration of spent γ-Al 2 O 3 could be well performed using NaOH solution.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2017
·
IF 2.536
Zhuomin Zhang,Yisen Zhan,Yichun Huang,Gongke Li
In this work, a portable large-volume constant-concentration (LVCC) sampling technique coupling with surface-enhanced Raman spectroscopy (SERS) was developed for the rapid on-site gas analysis based on suitable derivatization methods. LVCC sampling technique mainly consisted of a specially designed sampling cell including the rigid sample container and flexible sampling bag, and an absorption-derivatization module with a portable pump and a gas flowmeter. LVCC sampling technique allowed large, alterable and well-controlled sampling volume, which kept the concentration of gas target in headspace phase constant during the entire sampling process and made the sampling result more representative. Moreover, absorption and derivatization of gas target during LVCC sampling process were efficiently merged in one step using bromine-thiourea and OPA-NH 4 + strategy for ethylene and SO 2 respectively, which made LVCC sampling technique conveniently adapted to consequent SERS analysis. Finally, a new LVCC sampling-SERS method was developed and successfully applied for rapid analysis of trace ethylene and SO 2 from fruits. It was satisfied that trace ethylene and SO 2 from real fruit samples could be actually and accurately quantified by this method. The minor concentration fluctuations of ethylene and SO 2 during the entire LVCC sampling process were proved to be < 4.3% and 2.1% respectively. Good recoveries for ethylene and sulfur dioxide from fruit samples were achieved in range of 95.0–101% and 97.0–104% respectively. It is expected that portable LVCC sampling technique would pave the way for rapid on-site analysis of accurate concentrations of trace gas targets from real samples by SERS.
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JOURNAL OF CHROMATOGRAPHY A
·
2016
·
IF 3.926
Xiaohong Yang,Changxia Li,Meiling Qi,Liangti Qu
This work presents the separation performance of graphene-ZIF8 (G-Z) composite material as stationary phase for capillary gas chromatography (GC). The G-Z stationary phase achieved high column efficiency of 5000 plates/m determined by n -dodecane ( k = 1.22) at 120 °C and showed weakly polar nature. Importantly, it exhibited high selectivity and resolving capability for branched alkane isomers and aromatic positional isomers, showing clear advantages over the reported neat graphene and ZIF8. In addition, it attained high resolution for geometric cis -/ trans -isomers. The G-Z column exhibited good column thermal stability up to 300 °C and column repeatability with RSD values of retention times in the range of 0.01–0.19% for intra-day, 0.05–0.88% for inter-day and 0.66–5.6% for between-column, respectively, Moreover, the G-Z column was employed for the determination of minor impurity isomers in real reagent samples, which demonstrates its promising potential in GC applications .
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NANO
·
2016
·
IF 0.951
Zhiguo Sun,Jitao Yang,Li Zhang,Hongyong Xie
A new photocatalyst of sodium humate (HA–Na)/Nano-TiO 2 coating on the glass spheres for flue gas denitrification (DeNO x ) was prepared using the impregnation method. The HA–Na/TiO 2 is characterized by Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic activity of HA–Na/TiO 2 on removing NO x was investigated in a self-designed photocatalytic reactor. The synergistic mechanism of HA–Na and TiO 2 on DeNO x is also proposed and demonstrated. The experimental results indicate that specific surface area and average pore size of HA–Na are improved owing to the mixed TiO 2 nanoparticles. The crystal structure of TiO 2 has little change after mixing with HA–Na. Due to high photocatalytic performance of TiO 2 , NO was oxidized to NO 2 and HNO 3 eventually. On the other hand, HA–Na support can absorb and react with HNO 3 , which accelerates 10% of the catalytic reaction of TiO 2 and the utilization of light source. The chemical and physiological activity of oxidized HA–Na are improved than the original humate. The HA–Na/TiO 2 photocatalysts show great property on eliminating NO x because of the promoting effect between HA–Na and TiO 2 , and the NO removal efficiency can reach to 80% at the optimum condition.
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ENERGY & FUELS
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2016
·
IF 2.835
X. Liu,H. H. Jia,J. Zhou,X. Y. Yong,P. Wei,M. Jiang
CO2 removal is one of the key technological requirements in biogas purification. A technique using a gas–liquid mixing pump to capture CO2 and co-produce nano calcium carbonate was devised and tested in this work. The characteristic curves and CO2 absorption efficiency of the pump were investigated. The CO2 content of the end gas in all experiments was less than 2%, and the calcium carbonate samples showed that calcite was produced with a favorable particle size. A solution was proposed to deal with gas inlet blockage by preparing polyphenylene sulfide (PPS)–polytetrafluoroethylene (PTFE) coating. The coating had superhydrophobicity, self-cleaning ability, a unique microstructure, and good adhesion to the substrate. The gas inlet coated with PPS–PTFE could remain clean for at least 12 h, suggesting that the method used in this work was suitable. This work provides a novel approach for CO2 absorption and biogas purification.
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JOURNAL OF MEMBRANE SCIENCE
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2017
·
IF 6.035
Shuwen Yu,Shichun Li,Shiliang Huang,Zehua Zeng,Sheng Cui,Yu Liu
Mixed matrix membranes (MMMs) for gas separation show promising applications in energy and environment related fields. However, the poor compatibility between particles and polymers in MMMs is the main problem. Zeolitic imidazolate frameworks (ZIFs) as inorganic-organic hybrid porous materials have better compatibility with polymers than other inorganic particles, but interfacial defects between ZIFs and polymers still have been observed in MMMs. In this work, the interfacial compatibility in MMMs has been enhanced by building covalent bonds between amine modified ZIF-8 (NH 2 -ZIF-8) and polyamide in thin film nanocomposite (TFN) membranes prepared by in situ interfacial polymerization (IP). The attendance of amino groups on the surface of NH 2 -ZIF-8 was confirmed by both experiments and molecular simulation . The covalent bonds formed between NH 2 -ZIF-8 and trimesoyl chloride (TMC), the monomer in organic phase of IP, were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Compared with the TFN membrane with ZIF-8, the TFN membrane with NH 2 -ZIF-8 exhibits both higher CO 2 permeance and higher CO 2 /N 2 selectivity, which is mainly attributed to the enhanced interfacial compatibility and disturbed chain segment of polyamide by covalent bonds. Moreover, at high content of NH 2 -ZIF-8 in membranes, no interfacial crack appears between NH 2 -ZIF-8 and polyamide in membranes, which also confirms the excellent compatibility between NH 2 -ZIF-8 and polyamide. The TFN membrane with NH 2 -ZIF-8 shows high separation performance for CO 2 /N 2 , CO 2 /NO, and CO 2 /He gas pairs, which surpasses the Robeson's upper bounds.
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Scientific Reports
·
2015
·Vol. 5
·期 1
·1-6
·
IF 5.578
Yao Feng,Yi Bin,Shen Caihong,Tao Fei,Liu Yumin,Lin Zhixin,Xu Ping
Luzhoulaojiao liquor is a type of Chinese liquor that dates back hundreds of years, but whose precise chemical composition remains unknown. This paper describes the screening of the liquor and the identification of its compounds using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF-MS). Samples were prepared by both liquid-liquid extraction and solid-phase microextraction, which facilitated the detection of thousands of compounds in the liquor, thus demonstrating the superior performance of the proposed method over those reported in previous studies. A total of 320 compounds were common to all 18 types of Luzhoulaojiao liquor studied here and 13 abundant and potentially bioactive compounds were further quantified. The results indicated that the high-performance method presented here is well suited for the detection and identification of compounds in liquors. This study also contributes to enriching our knowledge of the contents of Chinese liquors.
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Catalysis Science & Technology
·
2014
·Vol. 4
·期 5
·1286-1292
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IF 4.76
Bing Liu,Ting Huang,Zehui Zhang,Zheng Wang,Yuhua Zhang,Jinlin Li
The present study reported the results on the water–gas shift (WGS) reaction over a series of Ru/C catalysts. It was found that the reduction method showed a remarkable effect on the catalytic activity of Ru/C catalysts over WGS reaction, which increased in an order of the reduction by NaBH4, ethylene glycol, H2. It has been shown that alkali additives with K2CO3 significantly improved the activity of the Ru/C catalysts. XPS results indicated that Ru species were further oxidized by the addition of K2CO3, which indicated an electron transfer from the alkali metal to the substrate, resulting in stronger bonding of the adsorbed gas. FTIR results showed that the absorption peak intensity of H2O and hydroxyl group increased with the increase of K2CO3 content, due to the strong hygroscopic ability of K2CO3. Through the addition of K2CO3 to the Ru/C catalyst, much more water was adsorbed around the catalytic active sites, reducing the strong adsorption of CO on the active sites. Thus the addition of K2CO3 balanced the concentration of water and CO on the active sites, which was considered to be the key step for low temperature WGS reaction over Ru supported on irreducible activated carbon.
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RSC Advances
·
2015
·Vol. 5
·期 119
·98500-98507
·
IF 3.84
Yunshi Liu,Ping Yang,Jia Li,Katarzyna Matras-Postolek,Yunlong Yue,Baibiao Huang
SnO2 and SnO2/CeO2 one dimensional (1D) nanostructures with various morphologies including solid nanofibers (NFs), nanobelts (NBs), nanotubes (NTs), and wire-in-tubes (WTs) were successfully prepared via a single-spinneret electrospinning process and a subsequent heat-treatment by adjusting the heating rate and the amount of CeO2. The interesting morphology evolution of samples from NTs to NBs was reported with increasing amounts of CeO2. In addition, SnO2 particles existed on the surface of the CeO2 matrix to form diverse structures in the 1D nanofibers. The band gap of the composite oxides decreased with the addition of CeO2. Compared with other nanostructures, SnO2/CeO2 NTs exhibited superior gas sensing properties, such as the highest response to ethanol. Due to the existence of Ce3+ and oxygen vacancies and the hollow structure, SnO2/CeO2 NTs revealed great CO oxidation performance, indicating the enhanced interactions between the catalyst and the target gas. These excellent properties were attributed to the prominent 1D hollow morphology, the good dispersion of SnO2 nanoparticles on the surface of the CeO2 matrix, the ideal crystallinity, and the composite interactions between the two oxides. In addition, the current method could be utilizable to fabricate other metal oxides with various morphologies for property controlling and important applications.
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JOURNAL OF CHROMATOGRAPHY A
·
2015
·
IF 4.169
Liang Hao,Dapeng Wu,Kun Ding,Hu Meng,Xiaohui Yan,Yafeng Guan
Thermal desorption–gas chromatography–mass spectrometer (TD–GC–MS) technique has been widely used for analysis of semi-violate organic compounds on atmospheric aerosol . To prevent GC column from being damaged by fine solid particles during thermal desorption process, glass wool as filter mat is indispensible. However, the filtration efficiency has never been validated. In this paper, the most penetrating particle size and the minimum packing thickness of glass wool were calculated based on classical filtration theory. According to the calculation results, packing parameters of glass wool were optimized experimentally using silica particles. It is demonstrated that glass wool with a packing thickness of 30 mm, solidity of 0.039 can effectively block these fine solid particles from penetrating at normal thermal desorption conditions ( T = 300 °C, u = 0.4–4 cm/s). Finally, the filtration efficiency of glass wool was further confirmed with real PM2.5 samples. Under the validated filtration condition, TD–GC–MS was applied for the analysis of non-polar organic compounds on real PM2.5 samples, and very good results were obtained.
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ANALYTICAL CHEMISTRY
·
2014
·
IF 5.825
Jun-Hui Zhang,Sheng-Ming Xie,Mei Zhang,Min Zi,Pin-Gang He,Li-Ming Yuan
Chiral nematic mesoporous silica (CNMS) has attracted widespread attention due to some unique features, such as its nematic structure, chirality, large pore size, high temperature resistance, low cost, and ease of preparation. We first reported the use of CNMS as a stationary phase for capillary gas chromatography (GC). The CNMS-coated capillary column not only gives good selectivity for the separation of linear alkanes, aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and isomers but also offers excellent enantioselectivity for chiral compounds. Compared with enantioseparations on commercial β-DEX 120 and Chirasil-l-Val columns, a CNMS-coated capillary column offers excellent enantioselectivity, chiral recognition complementarity, and the separation of analytes within short elution times. It can also be potentially applied in high-temperature GC at more than 350 °C. This work indicates that CNMS could soon become very attractive for separations.
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