Journal of Physical Chemistry C
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2019
·
IF 4.309
Zepeng Rao,Xiaofeng Xie,Xiao Wang,Asad Mahmood,Shengrui Tong,Maofa Ge,Jing Sun
A series of Er-doped TiO2 photocatalysts, using Er(NO3)3·6H2O precursor ranging from 0.5 to 2 mol %, were synthesized via sol–gel method with titanium(IV) isopropoxide solution as reactant. The structure and properties of as-prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, thermogravimetric analysis, photoluminescence, electrochemical impedance spectroscopy, and photocurrent. The as-synthesized Er-doped TiO2 nanoparticles demonstrated improved photocatalytic activities for the photodegradation of selected volatile organic compounds, including acetaldehyde, o-xylene, and ethylene. Additionally, high photodegradation of acetaldehyde was recorded in the visible region (λ > 420 nm). XPS analysis revealed that a handful of Er in anatase TiO2 was presented in the form of Er2O3, which benefited by increasing the specific surface area ranging from 59.28 to 110.34 m2/g and consequently enhanced the adsorption capacity for acetaldehyde, o-xylene, and ethylene 3.3, 3.7, and 3.8 times, respectively, in contrast to the undoped TiO2. Electron spin resonance results showed that Er doping caused production of oxygen vacancies (VO) and Ti3+, which promoted the photocatalytic activity of the catalyst. The TiO2 samples containing 0.5–1.5% Er content exhibited higher photoactivity in comparison with other samples. The highest removal efficiency of acetaldehyde and o-xylene within 100 min was 99.2 and 84.6%, respectively, and ethylene degradation efficiency reached 22.4% within 180 min. Furthermore, the visible light elimination efficiency of acetaldehyde was 25.5%. Finally, the results suggested that Er doping predominantly inhibited the catalyst poisoning in the degradation of o-xylene.
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ENERGY & FUELS
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2019
·
IF 3.021
Haiming Zhang,Bin Jiang,Na Yang,Na Zhang,Luhong Zhang,Zhaohe Huang,Xiaoming Xiao,Xiaowei Tantai
Ionic liquid (IL) aqueous solutions (aq) have emerged as promising candidates for SO2 absorption. In this work, a new series of diamino polycarboxylate protic ionic liquids (DPPILs) aq with low viscosities and high stabilities were developed and used for SO2 capture. All of the prepared absorbents could efficiently absorb low-concentration SO2 in simulated flue gas. Among them, DPPILs aq based on citric acid (CA) presented the most excellent SO2 desorption performance; nearly all absorbed SO2 could be easily desorbed under mild conditions. Particularly, N,N-dimethylethylenediamine citrate [DMEDA][CA] showed the highest available absorption capacity toward 0.2 vol % SO2 (up to 0.51 molSO2/molILs and 0.058 gSO2/gabs in 50 wt % aq at 20 °C), which also presented satisfactory SO2/CO2 selectivity, reusability, and SO2 removal efficiency. Fourier transform infrared and nuclear magnetic resonance spectroscopic analyses revealed that the protonation of [DMEDA]+ and [CA]− promoted SO2 absorption. Overall, the studied DPPILs aq with excellent physical properties, SO2 absorption–desorption performance, and stability may have a great perspective in industrial SO2 removal.
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Inorganic Chemistry Frontiers
·
2019
·Vol. 6
·期 8
·2043-2049
·
IF 5.934
Di Liu,Guangsheng Pang,Zhiyong Tang,Shouhua Feng
Interfacial engineering has demonstrated a significant effect on fabricating highly efficient membranes for gas separation. Herein, we introduced a new way to prepare a soft MOF membrane with a modified interface using polyelectrolyte branched polyethyleneimine (PEI) as the joint material. Assembled with layered graphene oxide (GO) and zeolitic imidazolate framework-8 (ZIF-8) nanocrystals, branched PEI not only functions as a soft coat onto the ZIF-8 surface to overcome the rigid nature but also well connects with GO nanosheets via electrostatic attraction, thus preventing the fracture of the membrane. When employed as the gas separation membrane for H2/CH4, the long gas diffusion pathway determined by layered GO and the accurate sieving effect endowed by ZIF-8 enable the remarkable permeance and selectivity. Furthermore, by simply altering the content of GO nanosheets and ZIF-8 nanocrystals in the composite membrane, one can easily adjust the permeance and selectivity toward the separation of H2/CH4 gas mixture.
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MACROMOLECULES
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2018
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IF 5.914
Shuangshuang Hou,Bien Tan
Exploring the effect of functional group substitution on the porous structure and gas adsorption performance of polymer materials is becoming much fascinating. Here, three novel polymers, based on various amine building blocks, were efficiently prepared by the solvent knitting method. It is intriguingly found that with the gradual functional group substitution of phenyl by naphthyl in building blocks both porosity and gas uptake capacity of these hyper-cross-linked polymers can be finely tuned, with SBET increased from 874 to 1717 m2 g–1, and CO2 adsorption capacity tuned from 12.76 to 18.85 wt % (273.15 K/1.00 bar). Besides, these polymers could reveal CO2/N2 selectivity up to 24.9 and CO2/CH4 selectivity of 6.3 at 298.15 K. This work has proved that increasing the number of naphthyl in precursors will be in favor of knitting microporous with improved porosity and enhanced gas uptake ability, and naphthyl outweighs phenyl in their contributions to bettering the porosity parameters and gas uptake capacity of synthesized polymers, which is crucially important for the further research.
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Environmental Chemistry
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2018
·Vol. 15
·期 7
·411-423
·
IF 2.923
Shuyan Wang,Lin Du,Narcisse T. Tsona,Wenxing Wang
Environmental context Acetate esters, emitted into the atmosphere from both natural and anthropogenic sources, can participate in photochemical processes leading to the formation of secondary organic aerosols. We report a study on the kinetics and mechanisms of the reaction of two acetate esters with O3, OH, NO3, and Cl radicals. The results help our understanding of the chemical behaviour of this important class of compounds in the atmosphere. The photodegradation reactions of isopropenyl acetate (IPA) and 2-methyl-2-propenyl acetate (MPA) initiated by O3, OH, Cl and NO3 radicals have been investigated in a 100 L Teflon reactor at 293 ± 3 K, by using gas chromatography with flame-ionisation detection as well as thermal desorption–gas chromatography–mass spectrometry to monitor the reactants and the products. The rate constants for the reactions of IPA and MPA with the four atmospheric oxidants were determined by using either absolute or relative rate methods. The following rate constants (in units of cm3 molecule−1 s−1) were obtained: k(O3 + IPA) = (0.37 ± 0.06) × 10−18, k(OH + IPA) = (6.44 ± 0.74) × 10−11, k(Cl+ IPA) = (4.33 ± 0.52) × 10−10, k(NO3 + IPA) = (1.62 ± 0.22) × 10−14, k(O3 + MPA) = (2.76 ± 0.40) × 10−18, k(OH + MPA) = (7.41 ± 0.92) × 10−11, k(Cl + MPA) = (3.33 ± 0.39) × 10−10, k(NO3 + MPA) = (1.34 ± 0.23) × 10−14. With the exception of the kinetic study of the reactions of O3 and OH with IPA and the mechanistic study of the reaction of IPA with O3, the current research reports the first kinetic and mechanistic investigation for these reactions at atmospheric pressure. Acetic anhydride and 1-acetoxyacetone are the main products of the reactions of IPA and MPA, respectively. On the basis of the products and estimated tropospheric lifetimes of the two esters, reaction mechanisms are proposed and the atmospheric implications are discussed.
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CHEMICAL ENGINEERING JOURNAL
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2018
·
IF 6.735
Shaolong Yang,Zhitao Han,Xinxiang Pan,Bojun Liu,Dongsheng Zhao
UV/chlorine has attracted much attention in flue gas and water treatment fields in recent years. However, only a few studies highlighted gas pollutants removal performance of UV/chlorine method in real water. In this study, nitrogen oxide (NO x ) removal using UV-irradiated electrolyzed seawater (UV/electrolyzed seawater) was explored under simulated seawater environment in a semi-batch photochemical reactor. Comparison experiments between UV/H 2 O 2 and UV/chlorine in both freshwater and seawater systems were performed. Results showed that NO removal efficiency in UV/chlorine freshwater system was higher than those in UV/chlorine seawater system, due to radical scavenging effects of water matrices in seawater. Several strong reactive radicals (e.g., OH, Cl, OCl, ClOH − ) yielded from UV/chlorine system were considered to contribute to NO x removal, among which the role of OH radical was confirmed by radical-trapping experiments. The alkalinity of the seawater adversely impacted contributions of these reactive radicals to NO x removal, which caused a sharp drop in NO x removal efficiencies. Comparatively, the chloride ion in seawater had slight influences on NO x removal efficiencies of UV/electrolyzed seawater. Then, optimization of NO x removal efficiencies against three key variables (active chlorine concentration, UV irradiation dose, and initial pH) was investigated in simulated seawater using Design Expert Software. A regression model of NO x removal efficiency was obtained with satisfactory accuracy. Results indicated that active chlorine concentration and UV irradiation dose significantly influenced NO x removal efficiencies, compared with pH effects. Furthermore, NO x removal mechanisms involved in reactive radicals were discussed for UV/electrolyzed seawater method. Due to pH-dependent characteristics of both active chlorine species and carbonate species in electrolyzed seawater, NO x removal pathways by UV/electrolyzed seawater were different as the environment changed from acid to alkalinity.
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Journal of Analytical Methods in Chemistry
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2018
·
IF 1.262
Mengsi Cao,Pingping Zhang,Yanru Feng,Huayin Zhang,Huaijiao Zhu,Kaoqi Lian,Weijun Kang
A reliable derivatization method has been developed to detect and quantify morpholine in apple juices and ibuprofen with gas chromatography-mass spectrometry. Morpholine can react with sodium nitrite under acidic condition to produce stable and volatile N-nitrosomorpholine derivative. In this experiment, various factors affecting the derivatization and extraction process were optimized, including volume and concentration of hydrochloric acid, quantity of sodium nitrite, derivatization temperature, derivatization time, extraction reagents, and extraction time. The derivative was extracted with dichloromethane and determined by gas chromatography-mass spectrometry. The linearity range of morpholine was 10–500 g·L−1 with good correlation, and limits of detection (LOD) and limits of quantification (LOQ) were 7.3 g·L−1 and 24.4 g·L−1, respectively. Low, medium, and high concentrations of morpholine were added in apple juices and ibuprofen samples to evaluate standard recovery rate and relative standard deviation. The spiked recovery rate ranged from 94.3% to 109.0%, and the intraday repeatability and interday reproducibility were 2.0%–4.4% and 3.3%–7.0%, respectively. The developed method has good accuracy and precision. This quantitative method for morpholine is simple, sensitive, rapid, and low cost and can successfully be applied to analyze the residual morpholine in apple juices and drug samples.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2018
·
IF 4.229
Long-Fei Xie,Pei-Gao Duan,Jia-Li Jiao,Yu-Ping Xu
A series of Ni catalysts with different zeolites were prepared by wet impregnation method and used to catalyze supercritical water gasification (SCWG) of microalgae for production of hydrogen-rich fuel gas under conditions of 430 °C, 60 min, ρ H₂O = 0.162 g/cm 3 , 2 g/g Ni/zeolites. Compared with noncatalytic SCWG, the presence of Ni/zeolite could increase the hydrogen gasification efficiency and carbon gasification efficiency by promoting water–gas shift and steam reforming reactions which are mainly affected by the amount of strong acid sites and Ni, respectively. The highest carbon gasification efficiency (CGE) and hydrogen gasification efficiency (HGE) of 23.61% and 23.55% were achieved with Ni/HY (Na 2 O, 0.8%). The gaseous produced mainly consisted of H 2 and CO 2 . The H 2 content in the gaseous products varied from 27.15 to 40.51% depending on the Ni/zeolites and increased with increasing the SiO 2 /Al 2 O 3 molar ratio of HZSM-5, which is 2.3–3.6 times higher than that of produced without catalyst. The H 2 yield varied between 2.57 and 3.61 mmol/g depending on the Ni/zeolites and increased from 2.19 to 5.61 mmol/g with increasing the SiO 2 /Al 2 O 3 molar ratio from 50:1 to 170:1, which is 3.6–7.8 times higher than that of produced without catalyst. Coke formation, surface area loss, and sintering of Ni could decrease the activity of the Ni/zeolites.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2019
·
IF 5.107
Zimu Xu,Xiaojuan Xue,Shuheng Hu,Yunxia Li,Jie Shen,Yan Lan,Rongxing Zhou,Fan Yang,Cheng Cheng
Norfloxacin (NOR) is a typical kind of Fluoroquinolone antibiotics which is extensively used around the world. Residues of NOR have been found continuously increasing in the water systems thus posing detrimental effects to the aquatic ecosystem and human health. In this study, the degradation effect and mechanism on NOR in aqueous solution are investigated by gas-liquid phase dielectric barrier discharge (DBD) plasma combined with different catalysts (H 2 O 2 or Fe 2+ ). The concentrations of three representative plasma-generated long-lived reactive species (H 2 O 2 , O 3 and N O 3 - ) were measured in dH 2 O and found enhancing with the lengthening discharge period. Variations on the treatment parameters were carried out in discharge power, initial solution pH and the concentration of catalysts. A discharge power at 60 W provided optimal balance on the degradation effect and energy efficiency would be beneficial, while there is not much impact from the initial solution pH on NOR degradation. Both H 2 O 2 and Fe 2+ at low concentration (0.5–10 mg/L of Fe 2+ , 0.1–1.0 mmol/L of H 2 O 2 ) were observed contributing to the improvement on the NOR degradation rate, while inhibition would occur at high concentration (10–20 mg/L of Fe 2+ , 1.0–2.0 mmol/L of H 2 O 2 ). The DBD/H 2 O 2 (0.5 mmol/L)/Fe 2+ (10 mg/L) system was found the optimal condition to achieve a high NOR degradation rate of more than 98% after plasma treatment for only 0.5 min at discharge power of 60 W. Moreover, 72.3 ± 1.7% of the total organic carbon (TOC) in NOR solution have been removed in the DBD/Fe 2+ (10 mg/L) system at 15 min which signifies a high mineralization efficiency. The cleavage of piperazine ring and quinolone ring, defluorination and hydroxylation are considered the major pathways for NOR degradation. The biological toxicity of the plasma/Fe 2+ -induced degradation intermediates has been detected and it fluctuated with the treatment time and finally declined. Therefore, the DBD/catalyst system could be an effective and promising method on pharmaceutical wastewater treatment in the future.
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Xiu-Xiu Fang,Wen-Min Liao,Jian-Dong Song,Wen-Zhi Jia,Yun Wang,Ji-Qing Lu,Meng-Fei Luo
A series of 3V-xFe/MgF 2 catalysts with different V/Fe molar ratios were prepared by a sol-gel method, and the effect of Fe promotion on the catalytic performance of gas-phase dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was investigated. It was found that proper V/Fe ratio was helpful to improve the activity. The 3V-0.5Fe/MgF 2 catalyst (with a V/Fe ratio of 6/1) gave a HFC-245fa conversion of 76.6% at 320 °C, which was 13.4% higher than that on the 3V/MgF 2 (63.2%). The synergy between V and Fe species resulted in enhanced surface acidity which accounts for the enhanced activity. The VO x and FeO x species in the fresh catalyst could be transformed to VOF x and FeF 3 species during the reaction, which were regarded as the active sites. However, higher content of Fe in the catalyst resulted in the partial coverage of V species, which led to decline of surface acidity and thus the suppressed activity. Also, surface carbon deposition was responsible for the slight catalyst deactivation .
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ChemCatChem
·
2018
·Vol. 10
·期 24
·5689-5697
·
IF 4.674
Wei Hong,Zhi-Qiang Wang,Shihui Zou,Yuheng Zhou,Linfang Lu,Qiuyue Zhou,Xue-Qing Gong,Jie Fan
Graphical Pt does it again ! The morphology of Pt nanoparticles was successfully regulated by calcinating Pt/SiO 2 catalysts in different atmospheres and achieved a 78.1 % cyclohexanone yield at 170 °C in oxidative dehydrogenation of KA-oil. It is industrially attractive to produce cyclohexanone directly from gas-phase oxidative dehydrogenation (ODH) of KA-oil (a mixture of cyclohexanone and cyclohexanol) since extra alcohol-ketone separation process can be potentially omitted. Herein, by simply tuning the calcination atmosphere of Pt/SiO 2 , we successfully regulated the morphology of Pt nanoparticles and optimized their catalytic performance in ODH of KA-oil. Pt/SiO 2 calcined in O 2 atmosphere showed a cube-like morphology and achieved a 78.1 % cyclohexanone yield at 170 °C, which surpassed its counterpart calcined in H 2 and most of the reported catalysts. Further experimental and theoretical calculation results indicated that cubic Pt nanoparticles possessed stronger adsorption ability to cyclohexanol and therefore performed better in ODH of KA-oil.
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JOURNAL OF CHROMATOGRAPHY A
·
2015
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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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