JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
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2021
·Vol. 147
·期 2
·1405-1419
·
IF 4.626
Zhao Xiao-Qiao,Wu Wen-Qian,Li Hua-bo,Chen Wang-Hua,Guo Zi-Chao,Chen Li-Ping
Adiabatic calorimetry is one of the main experimental methods to quantitatively study the thermal hazard in chemical process. There are two problems in adiabatic calorimetry: (1) identification of the reaction model is difficult; (2) the equilibrium of system and the temperature uniformity of sample will be broken under the rapid temperature rise rate, especially at lower thermal inertia. In this work, the heat-quench-heat method in adiabatic calorimetry was proposed to determine the reaction model and slow the reaction rate to evaluate kinetic parameters accurately. A criterion was proposed to identify the reaction model which states that the decomposition is an n-order reaction if T 0,stage1 < T 0,stage2 ; otherwise autocatalytic behavior was observed. Mathematical simulations have been conducted for n-order and autocatalytic decompositions. To further validate the method, it is applied to two representative substances: DTBP and CHP. The validity of this method has been verified by simulation and experiment results.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY
·
2019
·Vol. 38
·期 10
·2169-2177
·
IF 3.421
An He,Xinyong Liu,Liang Qu,Yongfei Gao,Jianfeng Feng,Lin Zhu
We exposed zebrafish ( Danio rerio ) to different concentrations of lead and cadmium, and monitored them for survival at 24, 48, 72, and 96 h. Metal toxicity was predicted and compared using the dose–response and general threshold survival models in terms of required data sets, fit performance, and applicability. Environ Toxicol Chem 2019;38:2169–2177. © 2019 SETAC.
研究领域:
环境毒理学
·
生态学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
THERMOCHIMICA ACTA
·
2021
·
IF 3.115
Xiao-Qiao Zhao,Wen-Qian Wu,Hua-bo Li,Wang-Hua Chen,Zi-Chao Guo,Li-Ping Chen
Adiabatic calorimetry is one of the main experimental methods to quantitatively study the thermal hazard in chemical process. In this work, a pressure-identification method has been developed to determine the reaction model and evaluate the kinetic parameters in adiabatic process. A theory, named ‘Equivalent adiabatic theory’ was proposed to verify the accuracy of the pressure correction, which states that the calculated generated gas amount is dependable if the equivalent adiabatic initial temperature is constant; otherwise, it is unreliable. Initial conversion calculated by credible generated gas amount can be used as a truth value to determine the kinetic model from models with good fitting by temperature data. Further, this method is applied to two representative substances: 20% DTBP in toluene and 25% CHP in cumene. The validity of this method has been verified by experiment results.
研究领域:
化学工程
·
安全科学
✓ 已验证
产品关联
DOI
高影响因子
KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2021
·Vol. 38
·期 9
·1810-1817
·
IF 3.309
Luan Wenwen,Wang Chunyu,Zeng Zuoxiang,Xue Weilan,He Xuelian,Bai Yu
The hydrolysis kinetics of polyvinyl butyral (PVB) was studied in ethanol/water mixed solvents in the temperature range of 339.15-355.15 K, and a three-step hypothesis was proposed to describe the hydrolysis process. The influences of stirring speed, ethanol content and temperature on the hydrolysis of PVB were investigated, and an induction period (IP) phenomenon was found in the process of PVB hydrolysis. The ethanol content in the mixed solvents has a great influence on IP, which is due to the formation of the two kinds of water-ethanol clusters in the system. Temperature influences the IP by changing the catalytic activity of hydroxylamine hydrochloride (HH) on the hydrolysis of PVB. The shrinking core models with three controlling steps were used to fit the kinetic data, and the results indicate that the model controlled by chemical reaction is suitable to describe the kinetic behavior of PVB hydrolysis.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 47
·27305-27317
·
IF 3.049
Jing Li,Jindi Huang,Ruiming Yin
This work aims to develop an effective method for investigating the multistage debinding kinetics and reaction mechanisms of removing N,N-dimethylacrylamide/N,N′-methylenebisacrylamide (DMAA/MBAM) polymer from gelcast ceramic parts. Thermogravimetry (TG) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to investigate the thermal degradation characteristics and the main compounds produced during the pyrolysis of DMAA/MBAM polymer within green components. A multi-stage parallel reaction model (M-PRM) was proposed to separate the overlapping peaks in the dα/dT curves. The kinetic parameters (activation energy E and pre-exponential factor k0) of each substage were calculated using model-free methods (Flynn–Wall–Ozawa, Starink, Friedman and Kissinger–Akahira–Sunose) and an activation energy variable model. In addition, the most appropriate kinetic mechanism function f(α) of each substage was analyzed and discussed via Málek's procedure and the Šesták–Berggren (SB) model. The results showed that the DMAA/MBAM polymer burnout in green components can be divided into three substages through a three-stage parallel reaction model (3-PRM). The values of E (Friedman method) for substages 1 to 3 were E(α) = 139.862 − 110.481α + 156.161α2 − 88.714α3 kJ mol−1, E(α) = 160.791 + 152.496α − 236.906α2 + 163.724α3 kJ mol−1 and E(α) = 72.132 + 452.830α − 669.039α2 + 507.015α3 kJ mol−1, respectively. The average values of E showed an increasing tendency from substages 1 to 3, and a kinetic compensation effect was also observed between the E and k0 in each substage. The kinetic mechanism analysis revealed that the reaction mechanisms for substages 1 to 3 were f(α) = (1 − α)0.668α3.049(−ln(1 − α))−3.874, f(α) = (1 − α)0.700α3.177(−ln(1 − α))−3.962 and f(α) = (1 − α)1.049α−0.161(−ln(1 − α))0.518, respectively. It is expected that the research results can be extended to investigate the multiplex debinding of binders or polymers for various colloidal molding techniques.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Chinese Physics C
·
2023
·Vol. 47
·期 3
·034001
·
IF 3.6
Long He,Junhua Luo,Li Jiang
Measurement of the cross-sections of the 79Br(n, 2n)78Br, 81Br(n, p)81mSe, 81Br(n, α)78As, and 79Br(n, α)76As reactions was performed at specific neutron energies, precisely, 13.5±0.2, 14.1±0.2, 14.4±0.2, and 14.8±0.2 MeV, relative to the standard 93Nb(n, 2n)92mNb and 27Al(n, α)24Na reference reactions using offline γ-ray spectrometry and neutron activation. Monoenergetic neutrons were generated at the China Academy of Engineering Physics via a 3H(d, n)4He reaction using the K-400 Neutron Generator equipped with a solid 3H-Ti based target. The activity of the reaction produce was obtained using a high-purity germanium detector. The cross-sections of the (n, 2n), (n, p), and (n, α) reactions on the bromine isotopes were measured in the 13–15 MeV neutron energy range. The covariance analysis approach was employed for a thorough inspection of any uncertainties within the measured cross-section data. A discussion and comparison of the observed outcome were carried out with previously published data, especially with the results of the JENDL-4.0, JEFF-3.3, TENDL-2019, and ENDF/B-VIII.0 data libraries, along with the theoretical excitation function curve derived by employing the TALYS-1.95 program. Improved cross-section restrictions for the investigated processes in the 13–15 MeV neutron energy range will be obtained using the current findings, which will help to raise the caliber of associated databases. Furthermore, the parameters of relevant nuclear reaction models can be verified using this data.
研究领域:
核物理学
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核工程
✓ 已验证
DOI
高影响因子
ChemElectroChem
·
2022
·Vol. 9
·期 12
·e202200236
·
IF 4.782
Jialian Ding,Ping Zhou,Bin Su
Graphical Electrochemiluminescence quantum efficiency (ECL-QE) : ECL-QE of Ru(bpy) 3 2+ /TPrA system was calculated in terms of a kinetic reaction model, which could reveal the root cause of ECL-QE change and could potentially be used as a criterion of selecting efficient luminophores and analytical conditions. Electrochemiluminescence quantum efficiency (ECL-QE) is an important parameter to evaluate the energy conversion ability of luminophores and analytical sensitivity of corresponding ECL systems. Herein, taking tris(2,2’-bipyridine)ruthenium(II) (Ru(bpy) 3 2+ ) and tri- n -propylamine (TPrA) coreactant system as an example, the ECL-QE was evaluated in terms of a kinetic reaction model, in which Ru(bpy) 3 3+ was considered to be the key intermediate in a reaction scheme consisting of competitive oxidative reduction and catalytic reaction routes. It was calculated as the product of electrochemical excitation efficiency ( η ex ) and light emission efficiency (i. e., photoluminescence quantum yield, PLQY). We used finite element simulations to examine the variation of η ex with the electrode material, applied potential, concentration and distance from the electrode surface. η ex was found to be largely determined by the electrochemical oxidation rate of TPrA that varied by several orders of magnitude with the electrode material. The estimation of ECL-QE helped in selecting the appropriate conditions for efficient ECL generation and sensitive analysis.
研究领域:
分析化学
·
电化学
✓ 已验证
DOI
高影响因子
ACS Omega
·
2022
·
IF 4.132
Jing Li,Jindi Huang
This work aims to provide useful insights into the thermal debinding kinetics of gelcast ceramic parts, especially for debinding kinetics prediction involving heat preservation. Debinding experiments were conducted in a differential thermogravimetric analyzer at five heating rates (5, 8, 10, 15, and 20 °C/min) in the temperature range of 35–900 °C under an air atmosphere. The conversion (α) and pyrolysis rate (dα/dT) data were simulated using a modified independent parallel reaction (IPR) model and a multiple normally distributed activation energy model (M-DAEM). Their validity was assessed and compared by checking the agreement between the experimental results and the prediction capability. The results showed that both the modified IPR model and M-DAEM had high predictability for thermal debinding kinetics under linear heating conditions. The fitting quality parameters (Fit) were less than 1.406 and 1.01%, respectively. The activation energies (Ei, i = 1, 2, 3, 4, and 5) calculated by the M-DAEM ranged from 153.312 to 217.171 kJ/mol. The relationships between Ei of pseudo components 1 to 5 calculated by the modified IPR model were a function of the conversion rate. The Ei values were E1(α) = 116.750 + 11.153α – 26.772α2 + 4.362α3 kJ/mol, E2(α) = 139.595 – 66.162α + 75.702α2 – 38.041α3 kJ/mol, E3(α) = 190.854 + 135.755α – 214.801α2 + 116.093α3 kJ/mol, E4(α) = 64.068 + 280.086α – 380.270α2 + 264.724α3 kJ/mol, and E5(α) = 188.257 – 77.086α + 74.129α2 – 48.669α3 kJ/mol, respectively. However, it is noteworthy that the α and dα/dT curves predicted by the modified IPR model with a deviation of less than 8% were better than those predicted by the M-DAEM for the linear thermal debinding process with the holding stage. Accordingly, it is believed that the proposed modified IPR model is suitable for describing the thermal debinding kinetics involving the heat preservation of gelcast green parts.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
THERMOCHIMICA ACTA
·
2024
·
IF 3.1
Xuebai Guo,Cuixia Liu
In this work, the pyrolysis behaviors and kinetics of two bamboo ( Bambusa texlitis ) wastes were investigated via thermogravimetric analysis. The weight loss behaviors of pyrolysis were studied by curvature of the conversion (α) curves. The curvature of α can depict the characteristic temperatures of pseudo component (hemicellulose, cellulose and lignin) pyrolysis. Model-free model was applied to estimate the apparent activation energies of the pure components for comparison with other kinetic models. Three parallel reaction (TPR) and parallel finite number first-order reaction (FNFOR) models were used for kinetic studies. The first-order TPR model underestimates the apparent activation energies of pseudo components. The n th-order TPR model underestimates the apparent activation energy of lignin and obtains characteristic temperatures that are inconsistent with those of pure lignin. The parallel FNFOR model is more reliable for simulating the kinetics of lignocellulosic biomass pyrolysis. The apparent activation energies of pseudo components depend on the variety of lignocellulosic biomass.
研究领域:
化学工程
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材料科学
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环境科学
·
生物能源
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Yi Guo,Rui Wang,Chang Shu,Hong Li,Xin Gao
Reactive distillation (RD) can be effectively used to improve the selectivity of the intermediate product for complex multi-reaction schemes, which involves using distillation to manipulate the column profiles in the RD column (RDC) to attribute the desired reaction and the manipulating reactions to facilitate separation. As the demand for ethyl methyl carbonate (EMC) has increased significantly due to its structural characteristics, the selective synthesis of EMC from the consecutive transesterification of dimethyl carbonate (DMC) and ethanol (EtOH) in the presence of azeotropes between reactants and products was studied as featured reaction schemes. The basic resin catalyst KC161 is utilized to build the kinetic reaction model and supplement the primary data for the process design. The pilot-scale RD experiments are explored to verify the feasibility and the reliability of the model. The impact of critical operation and structure parameters on the conversion and selectivity of the reaction and the azeotropes formed in the system were analyzed. A hybrid distillation process containing an RDC, pressure-swing distillation columns, and a regular distillation column, was designed and optimized based on minimized total annual cost (TAC) using a sequential iterative algorithm. 0. 9997 (mole purity) EMC and 0. 9999 (mole purity) diethyl carbonate (DEC) were obtained with EMC selectivity up to 0.863%.
研究领域:
化学工程
·
工艺化学
·
工业化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
He Sun,Yusheng Yang
Neodynium oxyfluoride has been applied for luminescence materials and solid electrolytes because of its structure combined advantages of rare-earth cations with F − and O 2− anions. Since the neodynium oxyfluoride with tetragonal structure retains a defect structure having anion vacancies where anions transfer, it shows higher anion conductivity than that with cubic and rhombohedral structures. The feasibility of synthesizing tetragonal neodynium oxyfluoride in molten fluorides was investigated in this work. The neodynium oxyfluoride was not dissolved in molten LiF–CaF 2 based on the in-situ observation using confocal scanning laser microscope, therefore neodynium oxyfluoride can be easily collected from molten fluorides. The neodynium oxyfluoride with tetragonal structure was successfully synthesized by the reaction of Nd 2 O 3 with molten fluorides. The synthesis process was analyzed by differential scanning calorimetry combining X-ray diffraction and scanning electron microscope. The reaction model was described and the reaction rate constant was calculated. According to the mathematical description of kinetic equation, the reaction rate could be proportional to the interface difference between molten fluorides and solid Nd 2 O 3 .
研究领域:
材料科学
·
固体化学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2024
·
IF 13
Guanqing Zhang,Fengqing Liu,Qiliang Zhu,Hao Qian,Shouchao Zhong,Jingze Tan,Anmin Zheng,Fujian Liu,Lilong Jiang
Herein, a variety of 2,6-diaminopyridine (DAP) derived nitrogen-doped hierarchically porous carbon (DAP-NHPC-T) prepared from carbonization-induced structure transformation of DAP-Zn-SiO 2 -P123 nanocomposites are reported, which are facilely prepared from solvent-free co-assembly of block copolymer templates P123 with pyridine-rich monomer of DAP, Zn(NO 3 ) 2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO 2 templates promote the formation of mesoporous and supermicroporous structures in the DAP-NHPC-T, while high-temperature volatilization of Zn contributed to generation of micropores. The DAP-NHPC-T possess large BET surface areas (≈956–1126 m 2 g −1 ), hierarchical porosity with micro-supermicro-mesoporous feature and high nitrogen contents (≈10.44–5.99 at%) with tunable density of pyridine-based nitrogen sites (≈5.99–3.32 at%), exhibiting good accessibility and reinforced interaction with SO 2 . Consequently, the DAP-NHPC-T show high SO 2 capacity (14.7 mmol g −1 , 25 °C and 1.0 bar) and SO 2 /CO 2 /N 2 IAST selectivities, extraordinary dynamic breakthrough separation efficiency and cycling stability, far beyond any other reported nitrogen-doped metal-free carbon. As verified by in situ spectroscopy and theoretical calculations, the pyridine-based nitrogen sites of the DAP-NHPC-T boost SO 2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.
研究领域:
材料科学
·
化学工程
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）