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Table of Content
28 December 2018, Volume 26 Issue 12
    Fluid Dynamics and Transport Phenomena
    Investigation of the hydrodynamics of slug flow in airlift pumps
    Zhineng Wang, Yong Kang, Xiaochuan Wang, Shijing Wu, Xiaoyong Li
    2018, 26(12):  2391-2402.  doi:10.1016/j.cjche.2018.04.015
    Abstract ( 692 )   PDF (1766KB) ( 193 )  
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    A slug flow model considering the dispersed bubbles entrained from the tail of Taylor bubble (TB) and recoalesced with the successive TB was proposed. Experiment was conducted to test the validity of this model by using a high-speed camcorder and particle image velocimetry (PIV). It was found that the model was valid for predicting the characteristics of slug flow in airlift pump within average error of 14%. Moreover, large pipe diameter was found to accelerate the rise velocity of TB and decreases void fraction in liquid slug by a small margin.
    Dynamic characteristics of charged droplets in an electrostatic spraying process with twin capillaries
    Jun Zhang, Hongzhou He, Guanxing Huang
    2018, 26(12):  2403-2411.  doi:10.1016/j.cjche.2018.03.006
    Abstract ( 576 )   PDF (2199KB) ( 34 )  
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    The experimental and simulated investigations on electrostatic spraying with twin capillaries are carried out. The starting electric voltage required for the cone-jet and the deposition characteristics of the droplets are measured. The whole spraying process, which includes jet and droplet motions, is simulated and the simulated results on the motions of jet and droplet are basically consistent with the experiments. According to the simulated results, the contributions of various electric forces to droplet movement are quantitatively analyzed and the droplet dynamic characteristics, especially the interaction mechanism between two sprays, are revealed. The test results on the droplet deposition characteristics partially support the simulated results on the droplet motion. The present work is useful for a better understanding on the interaction between sprays in double or multi-capillary system.
    Extra low friction coefficient caused by the formation of a solid-like layer: A new lubrication mechanism found through molecular simulation of the lubrication of MoS2 nanoslits
    Jiahui Li, Yudan Zhu, Yumeng Zhang, Qingwei Gao, Wei Zhu, Xiaohua Lu, Yijun Shi
    2018, 26(12):  2412-2419.  doi:10.1016/j.cjche.2018.02.027
    Abstract ( 532 )   PDF (824KB) ( 30 )  
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    Monolayer molybdenum disulfide (MoS2) is a novel two-dimensional material that exhibits potential application in lubrication technology. In this work, molecular dynamics was used to investigate the lubrication behaviour of different polar fluid molecules (i.e., water, methanol and decane) confined in monolayer MoS2 nanoslits. The pore width effect (i.e., 1.2, 1.6 and 2.0 nm) was also evaluated. Results revealed that decane molecules exhibited good lubricating performance compared to the other two kinds of molecules. The friction coefficient followed the order of decane < methanol < water, and decreased evidently as the slit width increased, except for decane. Analysis of the spatial distribution and mobility of different confined fluid molecules showed that a solid-like layer was formed near the slit wall. This phenomenon led to the extra low friction coefficient of confined decane molecules.
    Experimental research on stabilities, thermophysical properties and heat transfer enhancement of nanofluids in heat exchanger systems
    Cong Qi, Maoni Liu, Guiqing Wang, Yuhang Pan, Lin Liang
    2018, 26(12):  2420-2430.  doi:10.1016/j.cjche.2018.03.021
    Abstract ( 521 )   PDF (3121KB) ( 63 )  
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    Stable TiO2-water nanofluids are prepared by a two-step method, stabilities of nanofluids are investigated by precipitation method and transmittance method respectively, and thermal conductivities and viscosities are also measured. An experimental system for studying the heat transfer enhancement of nanofluids is established, and heat transfer and flow characteristics of TiO2-water nanofluids in heat exchanger systems with a triangular tube and circular tube are experimentally studied. The effects of nanoparticle mass fractions (ω=0.1 wt%-0.5 wt%) and Reynolds numbers (Re=800-10000) on the heat transfer and flow performances of nanofluids are analyzed. Fitting formulas for Nusselt number and resistance coefficient of nanofluids in a triangular tube are put forward based on the experimental data. The comprehensive performances of nanofluids in a triangular tube are investigated. It is found that nanofluids in a triangular tube can significantly improve the heat transfer performance at the cost of a small increase in resistance coefficient compared with that in a circular tube, especially the resistance coefficients are almost the same between different nanoparticle mass fractions at turbulent flow. It is also found that the comprehensive evaluation index η decreases with Reynolds number at laminar flow but a critical maximum value appears at turbulent flow.
    Experimental study on thermo-hydraulic performances of nanofluids flowing through a corrugated tube filled with copper foam in heat exchange systems
    Yongliang Wan, Runhan Wu, Cong Qi, Gang Duan, Ruizhao Yang
    2018, 26(12):  2431-2440.  doi:10.1016/j.cjche.2018.07.007
    Abstract ( 520 )   PDF (1171KB) ( 36 )  
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    Thermo-hydraulic characteristics of TiO2-water nanofluids in thin-wall stainless steel test tubes (corrugated tube and circular tube) filled with copper foam (40 PPI) are experimentally investigated and compared with those in test tubes without copper foam. The effects of nanoparticle mass concentration on flow and heat transfer performances are investigated. In addition, the mutual restriction relationships between Reynolds number (Re), Nusselt number (Nu) and resistance coefficient (f) are discussed respectively. Also, the comprehensive coefficient of performance (CCP) between heat transfer and pressure drop is evaluated. The results show that core-enhancement region for heat transfer using experimental tubes filled with copper foam is notably different from that of tubes without copper foam. There is a corresponding Reynolds number (about Re=2400) for the maximum CCP of each condition. And the heat transfer can be enhanced dramatically and sustained at 8000 ≤ Re ≤ 12000.
    Effects on the mixing process of a coiled tube after a T-junction: Simulation and correlation
    Shan Zhu, Kai Wang, Yangcheng Lü
    2018, 26(12):  2441-2447.  doi:10.1016/j.cjche.2018.04.003
    Abstract ( 530 )   PDF (659KB) ( 38 )  
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    Simulations were performed to examine the effects of a coiled tube after a T-junction on the mixing and flow characteristics. A coiled tube was found to have two effects:inducing a radial flow and flattening the axial velocity distribution, which enhances and weakens the mixing, respectively. In the straight tube section connecting the T-junction and coiled tube, the latter may dominate and cause the mixing to deteriorate. An experiment was performed with the Villermaux/Dushman method to verify the simulation results. Based on a mixing performance simulation with various fluid and geometric structure parameters, a dimensionless correlation was obtained that can be used to determine the mixing intensity along the coiled tube with a deviation of less than 1.5%. These results provide guidance for designing a coiled tube or optimizing the operating conditions to meet the mixing requirements of specific chemical processes.
    Separation Science and Engineering
    Hydrodynamics performance and tray efficiency analysis of the novel vertical spray packing tray
    Hongkang Zhao, Lun Li, Baohua Wang, Dan Yu, Qunsheng Li
    2018, 26(12):  2448-2454.  doi:10.1016/j.cjche.2018.01.030
    Abstract ( 559 )   PDF (598KB) ( 62 )  
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    Column setup has been widely utilized in the petroleum and chemistry industries. However, with the fast progress of industries and the increasingly serious energy shortage, designing a new column setup with better performance and higher capacity becomes more urgent. In order to improve column's capacity and expand operating condition, a new type of column tray named novel vertical spray packing (NVSP) tray was designed and experimented. The performances of the novel tray, including pressure drop, weeping, entrainment and tray efficiency, were tested in a plexiglass column. In addition, performances of the novel tray were compared with that of the sieve tray and the Glitsch V1 valve tray. Based on the experiment data, the mathematical correlations of pressure drop, weeping and entrainment for the novel tray were established by regression analysis method. A fundamental model of dry pressure drop of the novel tray was promoted at the form of sum mode. The results indicate that the novel tray has wider operating condition and better performance.
    Thermodynamical and catalytic aspects of zinc separation from aqueous solution
    Sajjad Aghazadeh, Mahdi Gharabaghi, Ziaedin Shafaei
    2018, 26(12):  2455-2460.  doi:10.1016/j.cjche.2018.07.022
    Abstract ( 498 )   PDF (490KB) ( 28 )  
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    The present research work examines extraction mechanism of zinc by D2EHPA (Di-2-ethyl hexyl phosphoric acid) and comprehensively studies the main effective parameters on the process. Results of thermodynamic experiments showed that zinc extraction by D2EHPA was endothermic and spontaneous, and thermodynamic parameters including entropy and enthalpy were+27.37 J·mol-1·K-1 and 25.21 kJ·mol-1, respectively. Gibbs free energy was varied between -7.21 kJ·mol-1 and -8.41 kJ·mol-1 with the variation of temperature from 20℃ to 70℃. Solution ionic strength was increased by addition of potassium and lithium sulfate solution while addition of calcium sulfate decreased ionic strength whereby zinc extraction efficiency was also decreased. TBP showed positive synergism at concentration of 5% (v/v) and negative synergism effect at concentrations of 2% and 10%. Simultaneous addition of both TBP and salt caused extraction efficiency to drop significantly and lower both TBP and ionic strength efficiency. Results showed that a continuous addition of TBP tends to effectively improve the zinc extraction efficiency. Experiments in the presence of catalyst Ni-Raney demonstrated that zinc extraction kinetic increases remarkably and due to easy recycling of the catalyst, we can propose a novel idea in solvent extraction field.
    Effects of pre-oxidant (KMnO4) on structure and performance of PVDF and PES membranes
    Xuehui Zhao, Yan Hu, Yun Wu, Hongwei Zhang
    2018, 26(12):  2461-2470.  doi:10.1016/j.cjche.2018.02.021
    Abstract ( 574 )   PDF (851KB) ( 37 )  
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    The structure and performance of membrane materials are very important to the efficient and stable operation in membrane drinking water purification technology. Potassium permanganate (KMnO4), which can change the characteristics of organic matters and control membrane surface fouling, has been widely used as pre-oxidant in the front of membrane drinking water process. This study investigates the evolution of membrane surface structure and performance when polyvinylidene fluoride (PVDF) and polyethersulfone (PES) were exposed to 10, 100 and 1000 mg·L-1 KMnO4 solution for 6 and 12 d, respectively. The aged membrane physicochemical characteristics such as membrane surface morphology, chemical composition, hydrophilicity, porosity and zeta potential were evaluated by modern analytical and testing instruments. The anti-fouling property of membrane surface was also investigated by the filtration-backwash experiment. The results indicated that the different concentrations and exposure time of KMnO4 led to a different variation on PVDF and PES membrane surface structure and performance, which could further affect the membrane separation performance and the membrane fouling behaviors. The membrane surface pore size and porosity increased due to the dislodgment and degradation of membrane additive (PVP), which improved membrane permeability and enhanced the adsorption and deposition of pollutants in the membrane pores. With the increase of exposure time, the membrane surface pore size and porosity reduced for the reactions of chain scission and crosslinking on membrane materials, and the backwashing efficiency declined, leading to a more serious irreversible fouling. Compared with PVDF membranes, the formation of sulfonic group for PES membranes increased the negative charge on membrane surface due to the oxidation of KMnO4. The present study provides some new insights for the regulation of the pre-oxidant dose and the selection of the membrane materials in KMnO4 pre-oxidation combined with membrane filtration system.
    Recovery of polyphenols from camu-camu (Myrciaria dubia H.B.K. McVaugh) depulping residue by cloud point extraction
    Carlos Eduardo de Araújo Padilha, Juliana Chris Silva de Azevedo, Francisco Canindé de Sousa Júnior, Sérgio Dantas de Oliveira Júnior, Domingos Fabiano de Santana Souza, Jackson Araújo de Oliveira, Gorete Ribeiro de Macedo, Everaldo Silvino dos Santos
    2018, 26(12):  2471-2476.  doi:10.1016/j.cjche.2017.10.032
    Abstract ( 485 )   PDF (275KB) ( 53 )  
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    In this study the potential of cloud point extraction formed by a non-ionic surfactant was used in order to separate polyphenols from industrial residues of camu-camu. The effects of operational conditions of the cloud point extraction (CPE) on the polyphenol recovery and volumetric ratio were investigated. The results showed a maximum recovery of 95.71% that was obtained using 7.0 wt% Triton X-114, native pH (3.25), and 80 wt% polyphenol extract at 30℃. The use of cloud point extraction was successful to recover the polyphenols from agroindustrial residue since it is a simple as well as of low-cost technique.
    Gas permeation properties of a metallic ion-cross-linked PIM-1 thin-film composite membrane supported on a UV-cross-linked porous substrate
    Hongyong Zhao, Lizhong Feng, Xiaoli Ding, Xiaoyao Tan, Yuzhong Zhang
    2018, 26(12):  2477-2486.  doi:10.1016/j.cjche.2018.03.009
    Abstract ( 662 )   PDF (1961KB) ( 48 )  
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    Metallic ion-cross-linked polymer of intrinsic microporosity (PIM-1) thin-film composite (TFC) membranes supported on an ultraviolet (UV)-cross-linked porous substrate were fabricated. The UV-cross-linked porous substrate was prepared via polymerization-induced phase separation. The PIM-1 TFC membranes were fabricated via a dip-coating procedure. Metallic ion-cross-linked PIM-1 TFC membranes were fabricated by hydrolyzing the PIM-1 TFC membrane in an alkali solution and then cross-linking it in a multivalent metallic ion solution. The pore size and porous structures were evaluated by low-temperature N2 adsorption-desorption analysis. The membrane structure was investigated by field-emission scanning electron microscopy. The effects of heat treatment and pore-forming additives on the gas permeance of the UV-cross-linked porous substrate are reported. The effects of different pre-coating treatments on the gas permeance of the metallic ion-cross-linked PIM-1 TFC membrane are also discussed. The metallic ion-crosslinked PIM-1 TFC membrane displayed high CO2/N2 selectivity (23) and good CO2 permeance (1058 GPU).
    An agent-based simulation with NetLogo platform to evaluate forward osmosis process (PRO Mode)
    Mostafa Taherian, Seyed Mahmoud Mousavi, Hooman Chamani
    2018, 26(12):  2487-2494.  doi:10.1016/j.cjche.2018.01.032
    Abstract ( 555 )   PDF (492KB) ( 102 )  
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    Forward osmosis (FO), as an emerging technology, is influenced by different factors such as operating conditions, module characteristics, and membrane properties. The general aim of this study was to develop a suitable (flexible, comprehensive, and convenient to use) computational tool which is able to simulate osmosis through an asymmetric membrane oriented in pressure retarded osmosis (PRO) mode in a wide variety of scenarios. For this purpose, an agent-based model was created in NetLogo platform, which is an easy-to-use application environment with graphical visualization abilities and well suited for modeling a complex system evolving over time. The simulation results were validated with empirical data obtained from literature and a great agreement was observed. The effect of various parameters on process performance was investigated in terms of temperature, cross-flow velocity, length of the module, pure water permeability coefficient, and structural parameter of the membrane. Results demonstrated that the increase in all parameters, except structural parameter of the membrane and the length of module led to the increase of average water flux. Moreover, nine different draw solutes were selected in order to assess the influence of net bulk osmotic pressure difference between the draw solution (DS) and feed solution (FS) (known as the driving force of FO process) on water flux. Based on the findings of this paper, the performance of FO process (PRO mode) can be efficiently evaluated using the NetLogo platform.
    The combination of 1-octyl-3-methylimidazolium tetrafluorborate with TBAB or THF on CO2 hydrate formation and CH4 separation from biogas
    Gang Yue, Aixian Liu, Qiang Sun, Xingxun Li, Wenjie Lan, Lanying Yang, Xuqiang Guo
    2018, 26(12):  2495-2502.  doi:10.1016/j.cjche.2018.03.014
    Abstract ( 552 )   PDF (612KB) ( 30 )  
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    [C8min] BF4 was used in this work to combine with TBAB or THF for the investigation about thermodynamic and kinetic additives on CO2 and CH4/CO2 hydrates. The results show that[C8min] BF4 has the inhibition effect on the equilibrium of hydrate formation. About the kinetic study,[C8min] BF4 could improve the rate of CO2 hydrate formation and increase the gas uptake in hydrate phase. At the same time, the combination of TBAB and[C8min] BF4 could increase the mole friction of CH4 in residual gas comparing with the data in THF solution. CH4 separation efficiency was strongly enhanced. Since that the size of CO2 and CH4 molecules are similar, CH4 and CO2 could form the similar hydrate, so the recovery of CH4 from biogas decreases lightly. The CH4 content in biogas can purified from 67 mol% to 77 mol% after one-stage hydrate formation. In addition, the combination of THF and[C8min] BF4 do not have obvious promoting effect on CH4 separation comparing with the gas separation results in pure THF solution.
    Modification of PES/PU membrane by supercritical CO2 to enhance CO2/CH4 selectivity: Fabrication and correlation approach using RSM
    Misagh Ahmadi, Sara Masoumi, Shadi Hassanajili, Feridun Esmaeilzadeh
    2018, 26(12):  2503-2515.  doi:10.1016/j.cjche.2017.11.018
    Abstract ( 534 )   PDF (1137KB) ( 135 )  
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    Integrally skinned asymmetric gas separation membranes of polyethersulfone (PES)/polyurethane (PU) blend were prepared using supercritical CO2 (SC-CO2) as a nonsolvent for the polymer solution. The membrane consisted of a dense and a porous layer, which were conjoined to separate CO2 from CH4. The FTIR, DSC, tensile and SEM tests were performed to study and characterize the membranes. The results revealed that an increase in SC-CO2 temperature causes an increment in permeance and a decrease in membrane selectivity. Furthermore, by raising the pressure, both permeance and selectivity increased. The modified membrane with SC-CO2 had much higher selectivity, about 5.5 times superior to the non-modified membrane. This higher selectivity performance compared to previous works was obtained by taking the advantages of both using partial miscible blend polymer due to the strong polar-polar interaction between PU PES and SC-CO2 to fabricate the membrane. The response surface methodology (RSM) was applied to find the relationships between several explanatory variables and CO2 and CH4 permeance and CO2/CH4 selectivity as responses. Finally, the results were validated with the experimental data, which the model results were in good agreement with the available experimental data.
    Microwave-assisted solvent extraction of castor oil from castor seeds
    Nur Atirah Ibrahim, Muhammad Abbas Ahmad Zaini
    2018, 26(12):  2516-2522.  doi:10.1016/j.cjche.2018.07.009
    Abstract ( 550 )   PDF (481KB) ( 168 )  
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    This study was aimed at evaluating the physicochemical properties and oxidation stability of castor oil using microwave-assisted solvent extraction (MAE). MAE was performed using 5% ethanol in hexane as solvent at different extraction times, power intensities and solvent-to-feed (S/F, ml of solvent to gram of feed) ratios. The process parameters were optimized by statistical approach using historical data design of response surface method (RSM). The oils were characterized for yield, physicochemical properties, dielectric properties and oxidation stability, and comparison was also made with oil extracted using Soxhlet method. Results show that the maximum oil yield of 37% was obtained at 20 min with microwave power intensity of 330 W and S/F ratio of 20. The main fatty acid composition of castor oil is ricinoleic acid. The density, refractive index, dielectric properties and oxidation stability of oils are not affected by the extraction methods and extraction parameters of MAE. However, the MAE-extracted oil is more viscous compared to that by Soxhlet method. With extra caution on oil oxidation, MAE could be a promising solvent extraction method with an 86% less in processing time and a higher yield.
    Facile synthesis of hierarchically porous carbons by controlling the initial oxygen concentration in-situ carbonization of ZIF-8 for efficient water treatment
    Na Zhou, Yan Du, Chunyu Wang, Rizhi Chen
    2018, 26(12):  2523-2530.  doi:10.1016/j.cjche.2018.05.014
    Abstract ( 466 )   PDF (795KB) ( 78 )  
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    The state-of-the-art approaches for adjusting the structural characteristics of porous carbons are the aftertreatments, which are complicated and time consuming. In this work, a facile approach was developed, i.e., controlling the initial oxygen concentration in-situ during the direct carbonization of zeolitic imidazole framework-8 (ZIF-8), to adjust the pore structure and prepare hierarchically porous carbons. The introduction of oxygen can significantly affect the crystalline and pore structures of porous carbons, and promote the pore widening and the formation of mesopores. An appropriate initial oxygen concentration can notably enhance the surface area and mesopore volume of porous carbon, and then improve the adsorption capacity toward methylene blue (MB) dye from water by 3.4 times. The developed approach is more efficient at lower carbonization temperature. Moreover, the introduction of oxygen can increase the ratio of HO-C=O groups on the carbon surface, leading to enhanced interaction with MB molecules and higher adsorption capacity toward MB. The as-prepared porous carbons exhibit superior adsorption capacities toward MB dye as compared to the reported ZIF-8 derived carbons. These findings would aid the development of porous carbon materials with high performance.
    Catalysis, kinetics and reaction engineering
    Aggregation and fragmentation of agglomerates in a fluidized bed of mixed nanoparticles by adding FCC coarse particles
    Hongbing Mo, Bao Xu, Chuanbao Luo, Tao Zhou, Jiangrong Kong
    2018, 26(12):  2531-2536.  doi:10.1016/j.cjche.2018.02.011
    Abstract ( 583 )   PDF (479KB) ( 41 )  
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    In this study, the influence of fluid cracking catalyst (FCC) on the fluidization behavior of ZnO-CuO binary nanoparticles was systematically investigated by varying FCC size. High-speed camera was employed to analyze the collision and fragmentation process of agglomerates with adding FCC coarse particles. It can be found from photographs by the camera that fluidization performance improved by the agglomerate variation that is bound to be shaped a compact and spherical structure. Furthermore, the result of agglomeration composition analysis showed that uniform mixing of nanoparticles remarkably affected the fluidization behavior of ZnO-CuO binary system. Finally, the improvement of fluidization performance can be justified by the analysis of inter-cohesive force between the two agglomerates with sharp reduction of the newly-formed agglomerates.
    Study on the pinene isomerization catalyzed by TiM
    Jionghua Xiang, Zhenghong Luo
    2018, 26(12):  2537-2541.  doi:10.1016/j.cjche.2018.02.005
    Abstract ( 514 )   PDF (419KB) ( 28 )  
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    The isomerization reaction of pinene is one of the most important chemical reactions in the deep processing of pinene. The purpose of this study is to improve the performance of the metatitanic acid by composite. The composite metatitanic acid catalyst TiM was prepared by adding Mn elements in the preparation process. The catalytic performance of TiM was evaluated. Comparison of TiM and metatitanic acid catalyst (Ti-FGP), the reaction rate of TiM catalyst was faster, and after the reaction, the yield of camphene and tricyclene increased about 1%. The catalysts were characterized by an SEM, FT-IR and laser particle size analyzer. The results show that the pinene isomerization reaction requires the synergistic action of the Brönsted acid and Lewis acid. Brönsted acid has great influence on the activity of catalyst, and Lewis acid has a great influence on the selectivity of the catalyst. The structure and morphology of the catalyst have a certain effect on the selectivity of pinene isomerization reaction.
    Mechanistic insights into the selective hydrogenation of resorcinol to 1,3-cyclohexanedione over Pd/rGO catalyst through DFT calculation
    Zuojun Wei, Haiyan Liu, Yidong Chen, Dechao Guo, Ruofei Pan, Yingxin Liu
    2018, 26(12):  2542-2548.  doi:10.1016/j.cjche.2018.01.031
    Abstract ( 576 )   PDF (402KB) ( 67 )  
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    In our previous work, graphene-supported Pd catalyst (Pd/rGO) exhibited higher activity and selectivity for the liquid phase selective hydrogenation of resorcinol to 1,3-cyclohexanedione compared with other catalysts. In the present study, further experimental and theoretical investigations were conducted to reveal the reaction mechanism and the catalytic mechanism of Pd/rGO for resorcinol hydrogenation. The effects of graphene nanosheet and the solvent on the reaction were investigated, and the pathway for resorcinol hydrogenation was proposed supported by density functional theory (DFT) calculations. The results showed that the excellent selectivity of Pd/rGO to 1,3-cyclohexanedione was attributed to the strong π-π and p-π interactions between the graphene nanosheet and the benzene ring as well as hydroxyl in resorcinol molecule, which was in agreement with our previous speculation. In weak polar aprotic solvents, solvation free energy had less impact to the π-π and p-π interactions mentioned above. In strong polar aprotic solvents and polar protic solvents, however, the influence of solvation free energy was much greater, which led to the decrease in the conversion of resorcinol and the selectivity to 1,3-cyclohexanedione.
    Process Systems Engineering and Process Safety
    Batch process monitoring based on WGNPE-GSVDD related and independent variables
    Yongyong Hui, Xiaoqiang Zhao
    2018, 26(12):  2549-2561.  doi:10.1016/j.cjche.2018.09.022
    Abstract ( 567 )   PDF (1845KB) ( 27 )  
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    In many batch processes, there are related or independence relationships among process variables. The traditional monitoring method usually carries out a single statistical model according to the related or independent method, and in the feature extraction there is not fully taken into account the characterization of fault information, it will make the process monitoring ineffective, so a fault monitoring method based on WGNPE (weighted global neighborhood preserving embedding)-GSVDD (greedy support vector data description) related and independent variables is proposed. First, mutual information method is used to separate the related variables and independent variables. Secondly, WGNPE method is used to extract the local and global structures of the related variables in batch process and highlight the fault information, GSVDD method is used to extract the process information of the independent variables quickly and effectively. Finally, the statistical monitoring model is established to achieve process monitoring based on WGNPE and GSVDD. The effectiveness of the proposed method was verified by the penicillin fermentation process.
    Application of convolutional neural networks to large-scale naphtha pyrolysis kinetic modeling
    Feng Hua, Zhou Fang, Tong Qiu
    2018, 26(12):  2562-2572.  doi:10.1016/j.cjche.2018.09.021
    Abstract ( 570 )   PDF (1446KB) ( 61 )  
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    System design and optimization problems require large-scale chemical kinetic models. Pure kinetic models of naphtha pyrolysis need to solve a complete set of stiff ODEs and is therefore too computational expensive. On the other hand, artificial neural networks that completely neglect the topology of the reaction networks often have poor generalization. In this paper, a framework is proposed for learning local representations from largescale chemical reaction networks. At first, the features of naphtha pyrolysis reactions are extracted by applying complex network characterization methods. The selected features are then used as inputs in convolutional architectures. Different CNN models are established and compared to optimize the neural network structure. After the pre-training and fine-tuning step, the ultimate CNN model reduces the computational cost of the previous kinetic model by over 300 times and predicts the yields of main products with the average error of less than 3%. The obtained results demonstrate the high efficiency of the proposed framework.
    Chemical Engineering Thermodynamics
    Measurement and correlation of phase equilibrium data of the mixtures consisting of water, resorcinol, mesityl oxide at different temperatures
    Youchang Wang, Shaoming Zhou, Jinhui Tang, Yun Chen, Libo Li
    2018, 26(12):  2573-2580.  doi:10.1016/j.cjche.2018.06.014
    Abstract ( 478 )   PDF (1180KB) ( 46 )  
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    Liquid-liquid equilibrium (LLE) data were measured for the ternary system of water+resorcinol+mesityl oxide under atmospheric pressure at temperatures of (298.2, 323.2, 333.2, 343.2 and 353.2) K. The reliability of the experimental data was verified by the Hand and Bachman equations. The distribution coefficient and selectivity were calculated from the experimental LLE data, which showed high efficiency of mesityl oxide extracting resorcinol from the aqueous solution. The NRTL and UNIQUAC models were employed to fit the measured experimental LLE data and yield corresponding binary interaction parameters.
    Electric conductivity and electric convertibility of potassium acetate in water, ethanol, 2,2,2-trifluoroethanol, 2-propanol and their binary blends
    Xi Wu, Shiming Xu, Debing Wu, Huan Liu
    2018, 26(12):  2581-2591.  doi:10.1016/j.cjche.2018.06.004
    Abstract ( 562 )   PDF (1201KB) ( 78 )  
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    Salinity gradient energy between the concentrated and diluted electrolyte solutions can be converted to electric energy by using reverse electrodialysis (RED) technology. Electrolyte solution is a vital factor that impacts the energy conversion efficiency. Potassium acetate (KAc) was chosen as solute, and water, ethanol, 2,2,2-trifluoroethanol (TFE), 2-propanol (IPA) and several of their binary mixtures were selected as solvents. Electric conductivity of these solutions were measured under varying conditions. KAc was easily ionized in water and possessed the maximum electric conductivity, following by KAc-H2O-TFE and KAc-H2O-ethanol, and then KAc in pure TFE, ethanol, and IPA respectively. For electric convertibility of these solutions working in a RED power generation system, it was found that the KAc-H2O possessed the maximum power density, and the KAc-ethanol-H2O possessed the larger open circuit voltage than aqueous KAc solution under the same working condition. Besides, it was observed that both the electric conductivity and electric convertibility were significantly influenced by the concentration and temperature of solution. With the increasing of concentration, electric conductivity of these solutions increased firstly and then reached to the peak, but later it decreased. Solution temperature took a positive impact role to the electric conductivity. Electric conductivity of these solutions can be estimated by using a modified amplitude version of Gaussian peak function.
    Biotechnology and Bioengineering
    Biochar-mediated regulation of greenhouse gas emission and toxicity reduction in bioremediation of organophosphorus pesticide-contaminated soils
    Meinan Zhen, Benru Song, Xiaomei Liu, Radhika Chandankere, Jingchun Tang
    2018, 26(12):  2592-2600.  doi:10.1016/j.cjche.2018.01.028
    Abstract ( 547 )   PDF (772KB) ( 64 )  
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    Organophosphorus pesticides (OPPs) are a set of toxic persistent organic pollutants (POPs) present in the environment. Recently, biochar-mediated bioremediation has exhibited many advantages over conventional methods for the remediation of pesticide-contaminated soil. In the present study, biochar and nitrogen fertilizer (NH4NO3) were employed to remediate OPP-contaminated soil and the greenhouse gas (GHG) emission during 90 days of incubation was investigated. After thermal desorption treatment, the content of organophosphorus pesticides reduced from 175.61 μg·kg-1 to 62.68 μg·kg-1. The addition of NH4NO3 in the following bioremediation led to larger reduction (34.35%) of the pesticide concentration than that of biochar (31.90%) for the contaminated soils with thermal desorption treatment, while the simultaneous addition of biochar and NH4NO3 led to the largest reduction of pesticide concentration (11.07%) for the soil without thermal desorption treatment. The addition of biochar and NH4NO3 only slightly increased the emission rate of GHGs from the soil without thermal treatment, but remarkably increased the emission rate of GHGs from the soil after thermal treatment. In most cases, the addition of NH4NO3 is more effective than biochar to promote the degradation of pesticide, but also exhibited higher GHG emission. The microbial community analysis suggests that the enhanced degradation of pesticide is mainly owing to the increased activity of microorganism.
    A cold adapt and ethanol tolerant endoglucanase from a marine Bacillus subtilis
    Dongsheng Xue, Xuhao Zeng, Chunjie Gong, Dongqiang Lin, Shanjing Yao
    2018, 26(12):  2601-2606.  doi:10.1016/j.cjche.2018.02.007
    Abstract ( 508 )   PDF (396KB) ( 48 )  
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    The catalytic properties and thermodynamic kinetics of the endoglucanase from a marine Bacillus subtilis were analyzed. Optimum pH and temperature of the endoglucanase activity were 5.0 and 35℃. The endoglucanase activity, melt point temperature was 1.13 folds (247.02 U·ml-1), 2.1℃ higher (39.2℃) in 6% ethanol solution than that (218.60 U·ml-1), (37.1℃) in free ethanol. At 40℃-55℃, Gibbs free energy, ΔG, and the content of α-helix was higher in 6% ethanol solution than that in ethanol free solution. The increasing of α-helix content led to higher activity and better thermostability in ethanol solution. The cold adapt ethanol tolerant endoglucanase was valuable for bioethanol product by simultaneous saccharification and fermentation process.
    Stability improvement of human collagen α1(I) chain using insulin as a fusion partner
    Yu Mi, Yuan Gao, Daidi Fan, Zhiguang Duan, Rongzhan Fu, Lihua Liang, Wenjiao Xue, Shanshan Wang
    2018, 26(12):  2607-2614.  doi:10.1016/j.cjche.2018.04.008
    Abstract ( 481 )   PDF (677KB) ( 45 )  
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    To enhance the stability of recombinant human collagen α1(I) chains (rhCOL1A1) in production and purification stages, a gene fragment fusing COL1A1 and insulin protein coding domains was synthesized and inserted into the pPIC9K expression vector. The fusion peptide-expressing Pichia pastoris strain was created by transformation. After optimization of shake flask cultures, the ultimate intracellular expression level of the insulin-collagen α1 (I) chain fusion protein (INS-COL1A1) reached about 300 mg·L-1, and no obvious protein degradation was found in the fermentation and purification processes. The His-tagged recombinant fusion protein was detected by western blotting and was effectively purified using Ni2+-chelating chromatography. A prominent improvement in the stability of INS-COL1A1 was observed compared to rhCOL1A1 in vitro, and the rhCOL1A1 released from the fusion protein was studied by LC-MS/MS and in bioassays. The results showed that the purified rhCOL1A1 was consistent with the native protein in amino acid composition and had a similar biological compatibility. To our knowledge, this is the first study to demonstrate the use of insulin as a fusion protein to improve the stability of easily degradable proteins.
    Reconstruction of tyrosol synthetic pathways in Escherichia coli
    Cui Yang, Xianzhong Chen, Junzhuang Chang, Lihua Zhang, Wei Xu, Wei Shen, You Fan
    2018, 26(12):  2615-2621.  doi:10.1016/j.cjche.2018.04.020
    Abstract ( 515 )   PDF (498KB) ( 79 )  
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    Tyrosol is a pharmacologically active phenolic compound widely used in the medicine and chemical industries. Traditional methods of plant extraction are complicated and chemical synthesis of tyrosol is not commercially viable. In this study, a recombinant Escherichia coli strain was constructed by overexpressing the phenylpyruvate decarboxylase ARO10 from Saccharomyces cerevisiae, which could produce tyrosol from glucose. Furthermore, genes encoding key enzymes from the competing phenylalanine and tyrosine synthesis pathways and the repression protein TyrR were eliminated, and the resulting engineered strain generated 3.57 mmol·L-1 tyrosol from glucose. More significantly, codon optimization of ARO10 increased expression and tyrosol titer. Using the novel engineered strain expressing codon-optimized AR10 in shake-flask culture, 8.72 mmol·L-1 tyrosol was obtained after 48 h. Optimization of the induction conditions improved tyrosol production to 9.53 mmol·L-1 (1316.3 mg·L-1). A higher titer of tyrosol was achieved by reconstruction of tyrosol synthetic pathway in E. coli.
    Energy, Resources and Environmental Technology
    Preparation optimization of multilayer-structured SnO2-Sb-Ce/Ti electrode for efficient electrocatalytic oxidation of tetracycline in water
    Kun Yang, Yuyu Liu, Jiawen Liu, Jinli Qiao
    2018, 26(12):  2622-2627.  doi:10.1016/j.cjche.2018.08.010
    Abstract ( 480 )   PDF (569KB) ( 51 )  
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    In this study, electrodeposition and thermal decomposition were alternatively used for the fabrication of a series of novel multilayer-structured SnO2-Sb-Ce/Ti (SSCT) electrodes, and their physiochemical and electrochemical properties were investigated for electrochemical oxidation of tetracycline (TC) in aqueous medium. Experimentally, after the SnO2-Sb-Ce (SSC) composite was electrodeposited for 120 s on the titanium substrate in aqueous solution, the outer thermal coatings composed of SSC were synthesized by a hydrothermal method. Both influences of electrodeposition time (Ted) and thermal decomposition time (Ttd) were investigated to obtain the optimum preparation. It was found that when increasing Ted to a certain extent a longer lifetime of electrode can be achieved, which was attributed to a more solid interlayer structure. A notable SSCTTed,Ttd electrode, i.e., SSCT3,10, which was prepared through three times of 120 s' electrodeposition (Ted=3) and ten times of thermal decomposition (Ttd=10) obtained the highest oxygen evolution potential 3.141 V vs. SCE. In this selected electrode, when 10 mg·L-1 initial TC concentration was added to this wastewater, the highest color removal efficiency and mineralization rate of TC were 72.4% and 41.6%, respectively, with an applied electricity density of 20 mA·cm-2 and treatment time of 1 h. These results presented here demonstrate that the combined application of electrodeposition and thermal decomposition is effective in realization of enhanced electrocatalytic oxidation activity.
    Facile ultrasonic-assisted synthesis of micro-nanosheet structure Bi4Ti3O12/g-C3N4 composites with enhanced photocatalytic activity on organic pollutants
    Huihui Gan, Futao Yi, Huining Zhang, Yongxing Qian, Huixia Jin, Kefeng Zhang
    2018, 26(12):  2628-2635.  doi:10.1016/j.cjche.2018.02.017
    Abstract ( 598 )   PDF (740KB) ( 63 )  
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    The Bi4Ti3O12/g-C3N4 composites with microsheet and nanosheet structure were prepared through facile ultrasonic-assisted method. The SEM and TEM results suggested that the nanosheets g-C3N4 were stacked on the surface of regular Bi4Ti3O12 sheets. Comparing with pure Bi4Ti3O12 and g-C3N4, the Bi4Ti3O12/g-C3N4 composites showed significant enhancement in photocatalytic efficiency for the degradation of RhB in solution. With the mass ratio of g-C3N4 increasing to 10 wt%, the Bi4Ti3O12/g-C3N4-10% presented the best photocatalytic activity. Its photocatalysis reaction constant was approximately 2 times higher than the single component Bi4Ti3O12 or g-C3N4. Meanwhile, good stability and durability for the Bi4Ti3O12/g-C3N4-10% were confirmed by the recycling experiment and FT-IR analysis. The possible mechanism for the improvements was the matched band positions and the effective separation of photo-excited electrons (e-) and holes (h+). Furthermore, based on the results of active species trapping, photo-generated holes (h+) and superoxide radical (·O2-) could be the main radicals in reaction.
    Effect of monovalent anions on cationic Gemini micro-emulsion
    Yinglu Gu, Shuang Chen, Hui'e Liu, Yubin Wang, Pingping Zhou
    2018, 26(12):  2636-2640.  doi:10.1016/j.cjche.2018.03.010
    Abstract ( 525 )   PDF (713KB) ( 36 )  
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    Micro-emulsion usually consists of water, oil, surfactants and co-surfactants, and each component has an effect on the phase behavior and solubilization of the micro-emulsion. When the surfactant in the micro-emulsion system is quaternary ammonium cationic Gemini surfactant, the surfactant mainly combines with the anions in the salt. With the increase of salt concentration, the phase transformation of Winsor I → Winsor Ⅲ → Winsor Ⅱ occurred, but the optimum salinity and salt width are different because of the type of salt. The effects of 5 different kinds of monovalent anions, including C6H5SO3-, I-, Br-, NO3- and Cl-, on the phase behavior and solubilization of quaternary ammonium cationic Gemini micro-emulsion are researched by Winsor phase diagram. It is found that the effects of organic anions C6H5SO3- and I- on the phase behavior and solubilization of quaternary ammonium cationic Gemini micro-emulsion are most significant, and the effects of Br-, NO3- and Cl- are less significant. Meanwhile, when the optimum solubilization is achieved, the amount of sodium benzoate is the least, indicating that the organic anion has stronger self-organization behavior with quaternary ammonium cationic Gemini surfactants.
    Materials and Product Engineering
    Red tetrazolium as an effective inhibitor for the corrosion of cold rolled steel in 7.0 mol·L-1 H2SO4 solution
    Xianghong Li, Shuduan Deng, Xiaoguang Xie
    2018, 26(12):  2641-2653.  doi:10.1016/j.cjche.2018.02.029
    Abstract ( 504 )   PDF (2714KB) ( 91 )  
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    The corrosion inhibition of cold rolled steel (CRS) in 7.0 mol·L-1 H2SO4 solution by red tetrazolium (RTZ) was carefully investigated using both experimental procedures and theoretical techniques. The results show that RTZ acts as an effective inhibitor for the corrosion of CRS in 7.0 mol·L-1 H2SO4, and the maximum inhibition efficiency is higher than 95% with a RTZ concentration of 2.0 mmol·L-1. The adsorption of RTZ on CRS surface follows Langmuir isotherm. RTZ effectively retards both cathodic and anodic reactions, and acts as a mixed-type inhibitor. EIS exhibits two capacitive loops, and their resistances increase drastically in the presence of RTZ. SEM and AFM confirm that the addition of RTZ could significantly retard the corrosion of CRS surface. A series of characterizations like FTIR, RS, XRD and XPS reveal that the corrosion CRS surface is composed of the corrosion products of iron sulfates, iron oxides and iron hydroxide, as well as inhibitor. Theoretical results of quantum chemical calculation and molecular dynamics (MD) indicate that the adsorption center of RTZ+ (organic cationic part of RTZ) mainly relies on its tetrazole ring, and the adsorption of RTZ+ on Fe (001) surface is in a nearly flat orientation mode.
    Synthesis, optimization and characterization of biochar based catalyst from sawdust for simultaneous esterification and transesterification
    Suchith Chellappan, Vaishakh Nair, Sajith V., Aparna K.
    2018, 26(12):  2654-2663.  doi:10.1016/j.cjche.2018.02.034
    Abstract ( 594 )   PDF (1141KB) ( 66 )  
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    The development of a benign environmental catalyst for the generation of biodiesel is an area of importance to reduce the overall usage of fossil fuels. In the current work, biochar was produced by slow pyrolysis of Irul wood sawdust. The optimization for biochar generation was carried out for different reaction temperatures and heating durations. The biochar was used to prepare solid acid catalysts by sulfonation process. The characterization of biochar and the sulfonated catalyst were carried out using Elemental analysis, Fourier Transform Infrared spectroscopy (FTIR), Powder X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Surface area analyzer (BET). The characterization results showed that sulfonation of biochar resulted in biochar based solid acid catalyst containing various functional acidic groups like weak acidic -OH groups, strong acidic -COOH and SO3H groups. The total acid density and sulfonic acid group density of catalyst were estimated and showed excellent acidic sites concentration which gives a good catalytic activity for biodiesel production through simultaneous esterification and transesterification. The enhanced catalytic activity is due to the high acid density of SO3H groups and the reactant accessibility towards acidic sites as well as the strong affinity between the hydrophilic reactants and the neutral OH groups which are bonded with the polycyclic aromatic carbon rings. The performance of biochar catalyst for the production of biodiesel was evaluated by comparing the yield obtained. The FTIR and Gas Chromatography-Mass Spectroscopy (GC-MS) were also carried out for the analysis of biodiesel produced.
    Preparation and characterization of tung oil-based flame retardant polyols
    Wei Zhou, Puyou Jia, Yonghong Zhou, Meng Zhang
    2018, 26(12):  2664-2671.  doi:10.1016/j.cjche.2018.03.011
    Abstract ( 545 )   PDF (739KB) ( 50 )  
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    Three kinds of tung oil-based structural flame retardants polyols (TOFPs) were prepared by new methods in this paper. First, tung oil was used to produce monoglyceride and diglyceride by transesterification with glycerol by sodium methoxide. The products after transesterification were epoxidized by peracetic acid which was in-situ generated from acetic acid and hydrogen peroxide in the presence of sulfuric acid catalyst. And then, TOFPs were prepared from epoxidized alcoholysis tung oil (EGTO) with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), diethyl phosphate (DEP) and diethanolamine (DEA) by ring-opening reactions, respectively. GPC was used to evaluate the conversion rate, at optimum reaction conditions, selectivity for monoglyceride in transesterification. The influence of different parameters such as temperature, mole ratio or mass ratio on the conversion rate of transesterification and epoxidation were investigated. The molecular structures of TOFPs were characterized by FTIR and 1HNMR. Finally, tung oil-based polyurethane foams (TOPUFs) were prepared by a one-shot process using TOFPs with polyisocyanate. The LOI values of TOPUFs whose content of DOPO-EGTO, DEP-EGTO and DEA-EGTO were 100 wt% can reach to 26.2%, 25.1%, and 24.4%, respectively.
    Classified index to 2018
    2018, 26(12):  2672-2681. 
    Abstract ( 238 )   PDF (261KB) ( 9 )  
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