JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2019
·Vol. 138
·期 2
·1251-1257
·
IF 2.471
Wang Yanfei,Liu Xiaoyu,Zhao Xiaoyu,Chen Zhao,Yang Libin,Zhu Liang
Solid–liquid-phase equilibrium is an important part of chemical thermodynamics, and its basic theoretical research plays a vital role in the advancement of the chemical industry. Solid–liquid equilibria for binary mixtures of 3-nitrotoluene and 4-nitrotoluene were measured using differential scanning calorimetry under atmospheric pressure (101.3 kPa). The results showed that the phase diagram of the 3-nitrotoluene + 4-nitrotoluene binary system presented a eutectic behavior, and the eutectic point was x 1 = 0.6487, T E = 272.15 K. Furthermore, the experimental results were correlated with Wilson and nonrandom two-liquid (NRTL) activity coefficient models well. The relative standard deviations were 0.496 and 0.236, respectively, and the absolute mean deviations were 0.005 and 0.001, respectively.
研究领域:
化学热力学
·
化工工程
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DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2021
·
IF 4.821
Jiankun Cao,Huayin Zhang,Sihui Liang,Qian Xu
Pyrene functionalized polyacrylonitrile nanofibers mat (Py-PAN NFM) was prepared via a green approach based on deep eutectic solvents . The Py-PAN NFM was further employed as solid-state fluorescent sensors for determining 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT) in real water samples. In order to adapt to the hydrophobicity of Py-PAN NFM surface, the water samples were extracted by dichloromethane, and then the extraction solvents were directly dropped onto the Py-PAN NFM. The conversion of sample polarity ensures that Py-PAN NFM does not need to be immersed in the water samples for a long time. The target TNT and DNT can immediately interact with the pyrene fluorophores on surface of Py-PAN NFM, thus accelerating the detection speed. Because the targets were also enriched through the conversion process, the sensing sensitivity has been significantly improved and the limits of detection of TNT and DNT can reach 8.81 × 10 −9 M and 2.74 × 10 −8 M, respectively. The Stern–Volmer plots for fluorescence quenching by TNT and DNT displayed an overall linearity in the entire tested concentration range with quenching constants of 2.57 × 10 6 M −1 and 3.15 × 10 5 M −1 , respectively. Moreover, the selectivity study indicated that other nitro compounds have an insignificant effect on the fluorescence sensing detection of TNT and DNT, and Py-PAN NFM can be reused at least 6 times without degradation in fluorescence-quenching performance. The theoretical calculations demonstrated that photoinduced electron transfer was involved in the quenching process and the fluorescence lifetime measurements revealed that a static quenching mechanism was suitable to explain the quenching behavior. The experimental results fully proved the practicability of this method in the rapid and sensitive monitoring of nitroaromatic compounds.
研究领域:
环境科学
·
分析化学
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DOI
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2022
·Vol. 101
·期 3
·1591-1601
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IF 2.5
Renjie Deng,Yao Tian,Huajie Liu,Weiwei Yan
This work presents a novel heterogeneous catalytic system for the preparation of para -nitrotoluene ( p -NT) with nitrogen dioxide (NO 2 ) as a nitrating agent in the presence of oxygen (O 2 ). By applying dealuminated Hβ zeolite treated with oxalic acid (Hβ-Ox) as a catalyst, p -NT can be obtained with high conversion (90.5%) and selectivity (72.6%). In addition, it can be recycled at least five times without a significant decrease in catalytic activity. This result demonstrates that the catalyst has high efficiency, good stability, and regenerability. Meanwhile, the characteristics of pristine Hβ and different dealuminated Hβ zeolites modified with organic and inorganic acids were systematic contrastive studied using X-ray diffraction (XRD), nitrogen (N 2 ) adsorption-desorption, Fourier-transform infrared (FT-IR), scanning electron microscope (SEM), temperature-programed desorption of ammonia (NH 3 -TPD), pyridine adsorption infrared (Py-FT-IR), and solid state 27 Al nuclear magnetic resonance ( 27 Al MAS-NMR). Finally, the higher conversion and para -selectivity over Hβ-Ox also give a reasonable explanation in this paper.
研究领域:
化学工程
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催化材料科学
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DOI
高影响因子
Catalysis Science & Technology
·
2024
·
IF 4.4
Renjie Deng,Huajie Liu,Haishuai Cui,Yao Tian,Hai Yang
In this work, we have developed a green method for the preparation of para-nitrotoluene through the catalytic nitration of toluene with nitrogen dioxide (NO2) under the promotion of dioxygen (O2). The experimental results reveal that the dealumination of Hβ zeolite has a significant effect on the catalysis of the developed NO2–O2–acetic anhydride (Ac2O) system, in which the conversion of toluene is 78.1% and the selectivity to para-nitrotoluene is 71.8%. Furthermore, the nature of different dealuminated catalysts was investigated by nitrogen adsorption–desorption analysis, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), thermal gravimetric analysis (TGA), inductively coupled plasma (ICP), ammonia temperature-programmed desorption (NH3-TPD), pyridine adsorbed Fourier-transform infrared (Py-FT-IR), scanning electron microscopy (SEM) and 27Al magic-angle spinning nuclear magnetic resonance (27Al MAS NMR) techniques. The results of characterization indicate that the structure of the Hβ zeolite still remains and that of Al species in the extra-framework is preferentially removed after acid treatment. Based on the combined results of catalytic characterization and DFT calculation, a feasible reaction mechanism of improved para-selectivity in toluene nitration was suggested for the NO2–O2–Ac2O system.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
AUSTRALIAN JOURNAL OF CHEMISTRY
·
2014
·Vol. 68
·期 6
·919-925
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IF 1.644
Jianping Wei,Fangmei Li,Junhui Xu,Xinhua Peng
New polynitrostilbenes were directly synthesised by the Knoevenagel condensation of aromatic aldehydes with nitrotoluenes. The differential scanning calorimetry results demonstrated that the introduction of an amino group and C=C double bonds could improve the thermal stability.
研究领域:
有机化学
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材料科学
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Zhifei Ma,Yu Yang,Yonghai Jiang,Beidou Xi,Tianxue Yang,Xing Peng,Xinying Lian,Kun Yan,Hongliang Liu
The reactivity of potassium persulfate (PP) in the degradation of 2,4-dinitrotoluene (2,4-DNT), with when iron and carbon as activators, is investigated. Effects of pH, persulfate concentration, and ionic strength on the degradation efficiency of 2,4-DNT by persulfate are studied in batch experiments, with simulated groundwater environmental conditions of no light, neutral pH and low temperatures (15 °C). The degradation of 2,4-DNT heightens and follows the pseudo-first-order kinetic model in the system comprising Fe/AC and S 2 O 8 2− . Addition of activated carbon (AC) increases the release of Fe 2+ to activate PP. When the concentration of persulfate is 100 mg/L, the 2,4-DNT degradation is the best at an initial pH of 2. The 2,4-DNT removal efficiency increases in the order of pH 2 > pH 9 > pH 3 > pH 5 > pH 11 > pH 7 in the Fe/AC + PP system. 2,4-DNT degradation in the presence of Cl − is slower in the first 100 min, but there is no obvious difference in degradation efficiency further on. This is most likely due to persulfate activation and Fe/AC reduction in this system. Meanwhile, the presence of bicarbonate ions inhibits the degradation of 2,4-DNT. A possible mechanism is proposed based on the reasons for the degradation of 2,4-DNT in the Fe/AC + PP system. Iron–carbon micro-electrolysis promotes micronmeter-sized iron to generate Fe 2+ . This study provides the design for an advanced, refractory organic matter-based oxidation technique for improved groundwater pollution remediation.
研究领域:
环境科学
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化学工程
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DOI
高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
·
2020
·Vol. 22
·期 5
·1-9
·
IF 2.132
Ma Zhifei,Yang Yu,Yang Tianxue,Wu Daishe,Peng Xing,Xi Beidou,Jiang Yonghai,Jia Yongfeng
To evaluate the longevity of the iron-activated persulfate (PS) oxidation degradation of 2,4-dinitrotoluene (2,4-DNT), zero-valent iron (ZVI), and three different micron-scale iron oxides were used as catalysts for the activation of PS. It was revealed that 2,4-DNT was degraded more effectively by ZVI and maghemite (γ-Fe 2 O 3 ) compared to that of hematite (α-Fe 2 O 3 ) and magnetite (Fe 3 O 4 ) catalyst treatments. Denitration of 2,4-DNT and oxidation of nitro groups as nitrate occurred by Fe 0 /PS and γ-Fe 2 O 3 /PS. When the 2,4-DNT removal rate was 1%, the generated sulfate concentrations of Fe 0 /PS and γ-Fe 2 O 3 /PS were 2.08 mg/L and 1.27 mg/L, respectively. Only micron scale γ-Fe 2 O 3 could activate PS for 2,4-DNT removal. ZVI was cycled and able to activate PS through multiple rounds. The size of the corrosion products of ZVI was more than 100 nm, and the particle size gradually increased in the cycling process. The first cycle of Fe 0 resulted in 45% removal of 2,4-DNT in 360 min. The 2,4-DNT removal efficiency (68.15%) increased after the second cycle, reaching the best removal efficiency in the fourth cycle. Oxidation products formed during degradation covered the ZVI surface, forming a shell. Adsorption of organic pollutants to this shell aids in the removal efficiency of 2,4-DNT and longevity of ZVI in groundwater.
Graphical abstract
研究领域:
环境科学
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化学工程
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DOI
高影响因子
TALANTA
·
2021
·
IF 6.057
Yongli Liu,Qingxiang Zhou,Yalin Wu,Shuangying Li,Yi Sun,Xueying Sheng,Yali Zhan,Jingyi Zhao,Jinghan Guo,Boyao Zhou
Carbon dots have been a promising nano-carbon material with many advantages, and attracted many more attentions. This study designed a new chemosensor integrating the strong fluorescent property of carbon dots and the magnetism of amino-functionalized magnetic core-shell nanomaterial , Fe@SiO 2 –NH 2 for determination of 2,4,6-trinitrotoluene (TNT). In this system, fluorescent carbon dots interacted with amino groups on the surface of amino-functionalized magnetic core-shell nanomaterial leading to fluorescence quenching of carbon dots, appearance of TNT competitively replaced of carbon dots on the surface of the magnetic material through forming a Meisenheimer complex. This sensor exhibits excellent selectivity and sensitivity for TNT, and which provided a good dynamic linear range for TNT from 10 to 2000 ng mL −1 . The experiments demonstrate a low detection limit of 2.15 ng mL −1 . The intra-day precisions for 25, 100 and 500 ng mL −1 were 4.6, 2.3 and 0.5% (RSD, n = 6), inter-day precisions for 25, 100 and 500 ng mL −1 were 4.2, 2.5 and 0.9% (RSD, n = 6), respectively. The developed sensor was validated with river water, dust, and soil samples, and the achieved spiked recoveries were immensely satisfied from 98.1% to 102.0%. The Fe@SiO 2 –NH 2 possessed excellent reusability. This sensor exhibits that it is simple, sensitive and selective, and will be a vital analytical tool for TNT in many fields.
研究领域:
分析化学
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环境科学
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产品关联
DOI
PubMed
高影响因子
Forensic Chemistry
·
2022
·
IF 3.096
Chao Huang,Jingyu Wang,Jingruolan Lin,Wei Huang,Yi He
Simple and convenient detection of 2,4,6‑trinitrotoluene (TNT) explosive is of great importance for public security and environmental protection. Herein we report the fabrication of a supramolecular visual colorimetric assay for TNT based on γ-cyclodextrin (γ-CD) molecular container. The hydrophobic cavity of γ-CD can encapsulate the hydrophobic TNT molecular because the molecular size of TNT is smaller than that of γ-CD. The γ-CD-TNT inclusion complex can react with NaOH to generate colored Meisenheimer complexes with enhanced absorption capacity, enabling highly sensitive colorimetric detection of TNT. Under optimal experimental parameters, the present visual colorimetric method displays a linear dynamic range of 0–200 μM with a detection limit of 0.8 μM, which shows 2-fold enhancement in the sensitivity compared with the γ-CD-free detection system. When the TNT concentration reaches 10 μM, it is discernible by the naked eye. Moreover, this assay is highly selective to TNT and applied for real water and soil samples. The spiked recoveries vary from 91.5% to 100%, demonstrating the potential practical applications.
研究领域:
化学
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环境科学
·
公共安全
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产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2024
·
IF 5.5
Lowell Toku Kokuloku,Elvis Djam Miensah,Aotian Gu,Kaiwei Chen,Peng Wang,Chunhui Gong,Yan Jiao,Kai Chen,Yi Yang
Background Activated carbon (AC) is commonly used to remove many pollutants from water due to its appealing adsorption properties. However, the pristine surface properties of AC limit its ability to effectively remove 2,4,6-trinitrotoluene (TNT, a widely used explosive water contaminant). Modifying AC with Fe nanoparticles (NPs) can significantly improve the surface properties of the Fe/AC composite, thereby enhancing its adsorption capabilities. Method Commercial charcoal-based AC was modified with Fe NPs via wet impregnation followed by a one-step carbothermal synthesis (labeled Fe-AC-800). A detailed characterization of Fe-AC-800 and its counterparts, pristine AC and thermally modified AC (AC-800, without Fe NPs doping) was performed using XRD, Raman Spectroscopy, SEM, EDS, BET, XPS, and FTIR. Then, the adsorption characteristics and performances of Fe-AC-800 were analyzed to determine its effectiveness in removing TNT and compared to AC and AC-800, considering the impact of in-situ Fe-modification and carbothermal treatment. Significant findings Fe-AC-800 displayed a higher adsorption capacity for TNT (387.74 mg/g) than the pristine AC (265.52 mg/g) but only slightly higher than AC-800 (339.64 mg/g). This was ascribed to the combined effect of the carbothermal treatment and Fe NPs doping, which constructed a richer porous structure that improved the Fe-AC-800 surface features and favored TNT removal. The optimal adsorption capacity of Fe-AC-800 was 464.13 mg/g under ambient conditions. TNT adsorption onto Fe-AC-800 and AC-800 conformed to only the Langmuir isotherm model, indicating uniform monolayer adsorption, whereas on the pristine AC, it satisfied both Langmuir and Freundlich isotherm models, respectively. The primary mechanism of TNT adsorption onto Fe-AC-800 was physical adsorption through pore filling, hydrogen bonding, and π-π EDA interactions, respectively.
研究领域:
环境科学
·
材料科学
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产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2015
·
IF 5.636
Sheng Huang,Qian He,Suying Xu,Leyu Wang
We report for the first time a photothermal paper sensor for the selective and sensitive detection of 2,4,6-trinitrotoluene (TNT) down to 14 ng/cm2. In the presence of TNT, a Meisenheimer complex was formed by means of a charge transfer process from an electron-rich group in polyaniline (PANI) to an electron-deficient nitro group in TNT, which resulted in the near-infrared absorption around 800 nm. Upon irradiation with an 808 nm diode laser, the photothermal effect of the PANI/TNT complex caused the temperature increase, and the temperature difference (ΔT) was proportional to the TNT concentration, while the temperature increase was hardly observed for other nitroaromatics including 2,4-dinitrotoluene (DNT), 2,4,6-trinitrophenol (TNP), and nitrobenzene (NB), affording high selectivity toward TNT. All the tests can be conducted both in solution and on paper. Therefore, the proposed photothermal strategy not only offers a fast and convenient protocol for selective detection of TNT but also indicates great potential in practical applications, especially for airport/railway security inspection and prevention of terrorist attacks.
研究领域:
化学传感器
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材料科学
·
环境监测
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2024
·Vol. 149
·期 24
·14715-14725
·
IF 3
Chen Peng,Chen Liping,Zhou Juan,Wu Wenqian,Guo Zichao,Chen Wanghua
Thermal analysis and calorimetry techniques with sealed sample cells are frequently employed to investigate the thermal stability of hazardous materials. However, the influence of sample mass on thermal decomposition is often ignored. To investigate the effect of sample mass on autocatalytic decomposition substances under sealed condition, 2,4-DNT was chosen for test and analysis. The techniques including differential scanning calorimetry (DSC), rapid screening calorimetry(RSC), high-performance liquid chromatography-mass spectrometry (HPLC–MS), and gas chromatography-mass spectrometry (GC–MS) were utilized for in-depth research on the decomposition of 2,4-DNT. The results revealed that an increase in sample mass led to an significant elevation in gaseous products such as CO 2 and CO with a negative heat of formation (ΔH f ). Then the system pressure and decomposition heat of 2,4-DNT increase significantly, thereby enhancing the thermal decomposition process. After that, it has been determined that o–nitrotoluene, m–nitroaniline, and o–nitrobenzoic acid can catalyze the decomposition of 2,4-DNT. Finally, it is advisable to increase the sample mass as much as possible when testing and analyzing such nitro compounds which would help ensure that the predicted results are closer to the actual conditions of production, transport, storage.
研究领域:
化学工程
·
材料科学
·
安全科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）