Desalination and Water Treatment
·
2016
·
IF 1.272
Xiao-ling Shao,Cheng-fei Zou,Fu-xing Wang,Yang Xiong,Xiang-yang Wu
The kinetics of the oxidation of chlorophenols (CPs) by potassium permanganate was studied in the present study, along with the changes in oxidant dosage, pH, temperature, and real water matrices. The reactions between permanganate and three kinds of CPs, i.e. 4-chlorophenol (4-MCP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP), are second order overall and first-order with respect to each reactant. The degradation rates of the CPs increase with increasing permanganate dosage or temperature. pH plays an important role during permanganate oxidation. With the increase in pH from 4.0 to 10.0, the reaction rates of 4-MCP and 2,4-DCP decrease first and then increase, and finally decrease rapidly when pH > pKa, while the rates of 2,4,6-TCP decrease continuously. The degradation rates of the CPs are obviously higher in real water than in pure water. The reaction rate follows the order of 2,4,6-TCP > 2,4-DCP > 4-MCP under acidic conditions, and follows the reverse order under alkaline conditions in both pure water and real water.
研究领域:
环境科学
·
化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 68
·39914-39923
·
IF 3.049
Cheng Qian,Yefei Wang,Zhen Yang,Zhengtian Qu,Mingchen Ding,Wuhua Chen,Zhenpei He
The in situ N2 generation technique is a promising method for enhancing oil recovery (EOR) and blockage removal. Conventionally, N2 is generated through the redox reactions of sodium nitrite (NaNO2) and ammonium chloride (NH4Cl). The effect of several parameters on N2 production was studied in this work. The reaction kinetics between NaNO2 and NH4Cl were developed. The results revealed that the optimal molar ratio was 1 : 1 for the reactants and a higher concentration of reactants, H+ and higher temperature would lead to an increase in the gas production volume and a better gas-generating efficiency. The kinetic equation of the N2 generation reaction was defined as dc/dt = −7.103 × 107 cH+1.3291c02.0949e(−51.28 kJ mol−1)/RT. Methyl formate, ethyl formate, ammonium persulphate as well as paraformaldehyde were selected as authigenic acids by measuring their pH values and their effect on the rate of gas-generation, and the gas production volume was studied. An energy enhancement experiment was conducted to examine the influence of reactant concentration, initial pressure and different authigenic acids on energy enhancement and gas-generating efficiency. The results showed that the increase in reactant concentration can improve the energy enhancement while neither the reactant concentration nor the initial pressure could hardly influence the gas-generating efficiency. The presence of authigenic acids can considerably enhance both the gas production volume and the gas-generating efficiency of the system. The ammonium persulphate assisted N2 generation system is considered to be suitable for field applications.
研究领域:
石油工程
·
化学工程
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Tu Lan,Qian Qiao,Fangxu Hu,De Li,Yong Chen
The electrochemical signals are very important to analyze and regulate the electrochemical systems, and the electrochemical oscillation is a newly discovered electrochemical signal in Li-ion batteries (LIBs), including the voltage and current oscillations. In this work, the Li4Ti5O12 was prepared using a home-made spray-drying instrument and high-temperature sintering, and its electrochemical oscillation was studied in LIBs. The electrochemical oscillation arose when the as-prepared Li4Ti5O12 precursor was sintered in a powder (not pellet) form, and it became stronger by reducing the lithium content in Li4Ti5O12. There are two types of electrochemical oscillation as a single-period oscillation or a double-period oscillation, and they can be transformed through varying the operating temperature, the current rate, and the conductive agent ratio, which might be owing to the electrochemical kinetics of Li4Ti5O12 electrodes. Combining the sintered forms and the X-ray photoelectron spectroscopy results, whether there is some fresh surface (formed by grinding the sintered pellet) becomes a typical difference between the powder-sintered and pellet-sintered Li4Ti5O12, which would affect the nucleation step and the reaction kinetics, and we proposed a possible reaction process of the electrochemical oscillation during the galvanostatic charging process of Li4Ti5O12 in LIBs.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Qi Lu,Kang Xue,Li Wang,Xiangwen Zhang,Ji-Jun Zou,Lun Pan
Alkyl decalins are promising jet fuel components with high density and well cryogenic properties, but are difficult to obtain. Here we bring up a facile approach to synthesize methyl-substituted decalins including methyl decalin, dimethyl decalin and trimethyl decalin via catalytic alkylation reaction. The reaction conditions are optimized to obtain the high decalin conversion of 83.1 %. Based on a series of experiments, it is indicated that the intermediate complex formed by tetramethylsilane, aluminum chloride and dichloroethane is the key to accelerate the reaction rate, and the reaction mechanism is proposed. Moreover, a pseudo-first-order irreversible reaction dynamics is studied, and the reaction kinetics parameters and reaction rate equati andons are obtained. After vacuum distillation, the fuel product shows high density (0.872 g/cm 3 ) and high volumetric neat heat of combustion (36.9 MJ/L), much higher than those of RP-3 fuel. This work provides a facile method to synthesize high-performance jet fuel.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Rao Chen,Chaoqun Yao,Shuainan Zhao,Xuan Liu,Yingjiang Lian,Guangwen Chen
It is critical for reactor design and process safety to determine the reaction kinetics for toluene nitration. Herein, a continuous-flow platform based on capillary microreactors was established. First, reaction regimes for toluene nitration and its consecutive side reaction (MNT (mononitrotoluene) nitration) were identified. On this basis, the influence of process parameters on conversion of toluene, selectivity of MNT and DNT (dinitrotoluene) and their isomer distribution were meticulously examined, including molar ratio of reactants, sulfuric acid strength, reaction temperature, and residence time. Subsequently, reaction kinetic models coupled with mass transfer were developed, allowing the simultaneous kinetic determination for toluene nitration and MNT nitration. It was found that the logarithm of the observed kinetic constant is proportional to the sulfuric acid strength. The kinetic parameters under 72.7 to 80.1 wt% sulfuric acid strengths were obtained. The outcomes provide a basis for process intensification and optimization of toluene nitration as well as other similar aromatics.
研究领域:
化学工程
·
过程强化
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Jinghua Wang,Hongyou Cui,Jiangang Wang,Zhihe Li,Ming Wang,Weiming Yi
Conversion of glucose to 5-hydromethyl furfural (HMF) and levulinic acid (LA) was systematically investigated in LiCl·3H 2 O without additional catalyst. Based on the experimental investigations by using glucose, fructose and HMF as the reaction substrate separately, corresponding reaction kinetics in LiCl·3H 2 O were modelled by first-order assumption. Kinetic analysis demonstrates that high temperature favors the formation of LA, while low temperature facilitates to selectively form humins. To achieve high LA yield, at least a temperature of 140 °C is required. Without additional catalyst converting glucose to LA in LiCl·3H 2 O, humins was predominantly derived from glucose and HMF, and glucose isomerization is the reaction rate-determining step. The activation energies of the main reactions are 160.96 kJ/mol (glucose to HMF), 139.20 kJ/mol (fructose to HMF), and 71.81–76.48 kJ/mol (HMF to LA) respectively. The activation energies for humins formation were 23.45 kJ/mol from glucose, 49.54 kJ/mol from fructose, and 42.15–65.85 kJ/mol from HMF, respectively. It is verified that LiCl·3H 2 O, as compared to aqueous medium, is an excellent reaction medium for converting glucose to LA as it can provide the active centers for fructose to HMF reaction and HMF to LA reaction, but lack of highly efficient Lewis acid for glucose isomerization. With the addition of Lewis acid (such as AlCl 3 and FeCl 3 ), as high as 83.4% of LA yield can be obtained respectively when directly converting glucose, with the total selectivities of LA and HMF of 95%.
研究领域:
生物化学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
·
2022
·
IF 5.582
Dong Wu,Yixing Huang,Qiang Zhang,Panding Wang,Yongmao Pei,Zeang Zhao,Daining Fang
It has long been observed when photo-curable resin is exposed to light, surface wrinkle pattern arises before the resin is fully photopolymerized. However, the critical condition for the onset of surface instability during photopolymerization process and how the wrinkling initiation is affected by photopolymerizing condition have not been theoretically resolved yet. In this paper, the onset of wrinkling initiation of a photopolymerization system is experimentally and theoretically investigated. The morphological patterns of surficial wrinkles are captured and characterized by in-situ monitoring of wrinkling initiation. Instability analysis of the transient and inhomogeneous photopolymerization system is implemented by state space method, combing the photochemical reaction kinetics with the coupled diffusion and large deformation theory of polymeric materials. Both the critical time and critical wavelength for wrinkling initiation can be predicted by our model, which is verified by experimental results. The critical time is significantly affected by the curing conditions that impact on the photochemical reaction kinetics, including irradiation intensity and photoinitiator concentration. Higher irradiation intensity and photoinitiator concentration can promote transformation of monomer and accelerate self-swelling behavior, generating a shorter time to surface instability. The critical wavelength is mainly affected by the mechanical properties of the material. Curing a thicker film with lower irradiation intensity and lower photoinitiator concentration results in a higher non-uniformity of material property, and generating a larger wavelength of wrinkle in the polymer surface. The theoretical and experimental analysis in this work provide guiding principles for controlling of surface morphology in photopolymerization-based designing and manufacturing.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2010
·
IF 4.144
Bin Yang,Guang-Guo Ying,Jian-Liang Zhao,Li-Juan Zhang,Yi-Xiang Fang,Long Duc Nghiem
The oxidation of triclosan by commercial grade aqueous ferrate (Fe(VI)) was investigated and the reaction kinetics as a function of pH (7.0–10.0) were experimentally determined. Intermediate products of the oxidation process were characterized using both GC–MS and RRLC–MS/MS techniques. Changes in toxicity during the oxidation process of triclosan using Fe(VI) were investigated using Pseudokirchneriella subcapitata growth inhibition tests. The results show that triclosan reacted rapidly with Fe(VI), with the apparent second-order rate constant, k app , being 754.7 M −1 s −1 at pH 7. At a stoichiometric ratio of 10:1 (Fe(VI):triclosan), complete removal of triclosan was achieved. Species-specific rate constants, k , were determined for reaction of Fe(VI) with both the protonated and deprotonated triclosan species. The value of k determined for neutral triclosan was 6.7(±1.9) × 10 2 M −1 s −1 , while that measured for anionic triclosan was 7.6(±0.6) × 10 3 M −1 s −1 . The proposed mechanism for the oxidation of triclosan by the Fe(VI) involves the scission of ether bond and phenoxy radical addition reaction. Coupling reaction may also occur during Fe(VI) degradation of triclosan. Overall, the degradation processes of triclosan resulted in a significant decrease in algal toxicity. The toxicity tests showed that Fe(VI) itself dosed in the reaction did not inhibit green algae growth.
研究领域:
环境科学
·
毒理学
✓ 已验证
DOI
PubMed
高影响因子
Journal of Materials Chemistry A
·
2023
·Vol. 11
·期 40
·21645-21654
·
IF 11.9
Min Zhang,Zhihong Du,Zhipeng Sun,Hailei Zhao
Iron-based double perovskites, as mixed electronic and oxygen ionic conductors, are potential air electrodes for reversible solid fuel cells. However, their catalytic activity towards the oxygen reduction reaction/oxygen evolution reaction is inferior to that of cobalt-based perovskites. Herein, a BaCO3-infiltrated SmBaFe2O5+δ (SBF) electrode is proposed with significantly enhanced catalytic activity. The theoretical computation and experimental study demonstrate that BaCO3 can significantly accelerate the oxygen adsorption/dissociation kinetics, which is identified to be the rate-limiting step of the SBF electrode. The BaCO3 decoration decreases significantly the polarization resistance from 0.154 to 0.068 Ω cm2 at 700 °C in air, and enables superior electrochemical performance in both fuel cell (FC) and electrolysis cell (EC) modes. The single cell with BaCO3 infiltrated SBF as an air electrode exhibits good operational stability in a reversible FC/EC mode for 34 cycles at ±300 mA cm−2, manifesting the good structural stability of the BaCO3-infiltrated SBF composite electrode under redox conditions. This work highlights the importance of clarifying the rate-limiting step and finding an effective strategy to facilitate this specific process for the design of high performance electrode materials.
研究领域:
材料科学
·
能源科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
·
2021
·
IF 1.134
Yong-Sheng NIU,Li-Xin SUN,Cong-Wei HU,Jin-Hao ZHOU,Qiang DOU,Qing-Nuan LI
The fluorination behavior of molybdenum (Mo) powder with NF 3 , such as temperature dependence of reactivity, reaction mechanism and kinetics were investigated on a homemade fluoride volatility process (FVP) research device. The in-situ Fourier transform infrared (FTIR) spectroscopy was applied to determine the beginning and the end of reaction. The research demonstrated that near 500 K or lower, the reaction between Mo power and NF 3 occurred, meanwhile, the temperature had an important influence on the average reaction rate and the utilization of NF 3 . When the temperature increased from 500 K to 700 K, the average rate increased from 1.04 × 10 –2 mol/h to 2.40 × 10 –2 mol/h and the utilization of NF 3 increased from 21.2% to 49.0%. The in-situ FTIR and XRD analysis assisted by thermodynamic calculation indicated that Mo power was converted to MoF 6 through an intermediate product MoF 3 : 2NF 3 (g) + 2Mo (s) = 2MoF 3 (s) + N 2 (g), then 2MoF 3 (s) + 2NF 3 (g) = 2MoF 6 (g) + N 2 (g). Based on a mathematical model with unreacted shrinking core, the calculated reaction rate constant increased from 1.77 × 10 –2 min –1 to 3.48 × 10 –2 min –1 in the temperature range of 500–700 K, and the activation energy was 10.13 kJ/mol.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2019
·
IF 6.97
Mingjie Chen,Rui-Min Li,Troy Runge,Jin Feng,Jing Feng,Songnan Hu,Qing-Shan Shi
Cellulose acetate is one of the oldest synthetic thermoplastic polymers and has various applications including usage as films, fibers, and membrane products. Traditionally, cellulose acetate is prepared by reacting cellulose with acetic anhydride in acetic acid using sulfuric acid as a catalyst. This process suffers from extensive depolymerization of the cellulose molecules and corrosion of the equipment from the use of the acidic solvent and catalyst. Herein we present an acid-free cellulose acetylation process using vinyl acetate as both the reactant and reaction medium and 1-ethyl-3-methylimidazolium acetate as the catalyst. The obtained cellulose acetate was confirmed by FTIR, NMR, and XRD studies. Additionally, the reaction kinetics, mechanism of the process, and properties of the obtained cellulose acetate were studied. Cellulose triacetate was obtained by our process within 2 h at 90 °C. The reaction kinetics was described with the classical pseudo-first-order rate expression of heterogeneous cellulose acetylation. The reaction mechanism was shown to be a peel-off mechanism similar to that of cellulose acetylation by the traditional acetic acid process. The molecular weight of the cellulose acetate produced by this new process was significantly higher than that from the traditional acetic acid process because of the absence of strong acids, which can depolymerize cellulose. In summary, we describe a new acid-free process to produce cellulose acetate that limits cellulose depolymerization and avoids the use of corrosive chemicals.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Nano Energy
·
2021
·
IF 17.881
Mengdie Yan,Chenlu Xu,Yang Sun,Huilin Pan,Hong Li
The reaction kinetics, reversibility and long-term stability of Zn anodes are crucial for rechargeable aqueous Zn batteries . Polymer electrolyte additives are low cost and effective to modify the deposition behavior of Zn anodes. Here, an interesting phenomenon appears that cycling stability and Coulombic efficiency of Zn anodes are improved by PEO additive in dilute aqueous electrolytes with different Zn salts, while the overpotential and long-term stability of Zn anodes vary significantly with different anions. Systematic electrochemical analysis coupled with NMR and MD simulation was performed to reveal the crucial role of salt anion in tuning the specific solvation structures and hydrogen bonding network of aqueous electrolytes with PEO additive, and interfacial double layer capacitance structures. The reaction kinetics and stability of Zn anodes were, therefore, intensively tuned by salt anions in aqueous electrolytes with PEO additives. The cycle life of Zn anode can be improved by 7–10 times with significantly reduced overpotential in bulky anion such as TFSI - based aqueous electrolyte than compact anion such as SO 4 2- in PEO containing aqueous electrolytes. This work provides useful and low-cost concepts to effectively improve Zn anodes reaction dynamics and cycle life by choosing optimal electrolyte salts and additives.
研究领域:
电化学
·
材料科学
✓ 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）