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Table of Content
05 January 2020, Volume 71 Issue 1
    Reviews and monographs
    Higee process intensification technology and application for oceaneering
    Liangliang ZHANG, Jiwen FU, Yong LUO, Baochang SUN, Haikui ZOU, Guangwen CHU, Jianfeng CHEN
    2020, 71(1):  1-15.  doi:10.11949/0438-1157.20191374
    Abstract ( 1222 )   HTML ( 40)   PDF (4445KB) ( 608 )  
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    Higee (high gravity) technology, which is carried out in rotating packed bed (RPB), is one of the typical chemical process intensification technologies. Due to its small size, high mass transfer and high separation efficiency, it has been successfully applied in the chemical process on offshore platform. The structure and principle of RPB was introduced, and the related works was summarized in terms of fundamental research, mathematic modeling and CFD simulation of RPB, which provides theoretical support for the wide application of Higee technology. Finally, the industrial application of natural gas dehydration, desulfurization and water deoxidation in the oil and gas production of offshore platforms by supergravity technology is introduced.

    Functional ionic liquids for carbon dioxide capture and separation
    Guokai CUI,Shuzhen LYU,Jianji WANG
    2020, 71(1):  16-25.  doi:10.11949/0438-1157.20191288
    Abstract ( 1009 )   HTML ( 54)   PDF (583KB) ( 500 )  
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    Carbon dioxide capture and separation (CCS) is one of the main strategies to reduce carbon emissions and cope with global climate change. It is of great significance to develop highly selective absorbents and new routes to efficiently absorb and separate CO2. Recently, ionic liquids (ILs), especially functional ionic liquids, have been developed as a kind of representative material in the last 20 years due to their unique properties, such as ultra low vapor pressure, wide liquid temperature range, high thermal and chemical stability, wide electrochemical steady window, non-flammability, and tunable structure and properties. Thus, many attentions have been drawn on the absorption and separation of CO2 by using ILs. The current review focuses on the studies on functional ILs for CO2 capture and separation during the last five years (2015—2019), including recent progress on the applications of single site functional ILs, multiple sites functional ILs, functional IL-based mixtures, and functional IL-based hybrid materials in CCS. Finally, the challenges in the absorption and separation of CO2 from flue gas as well as further researches in this field have been discussed.

    Methods for measuring vaporization enthalpies of ionic liquids
    Sijie SONG,Jia YAO,Haoran LI
    2020, 71(1):  26-33.  doi:10.11949/0438-1157.20191240
    Abstract ( 487 )   HTML ( 14)   PDF (605KB) ( 303 )  
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    Due to their characteristics, such as low vapor pressure, low volatilization, strong electrical conductivity, stable chemical properties, recyclability and so on, ionic liquids (ILs) can replace organic solvents as a new environmentally friendly solvent, can be used as a catalyst to catalyze chemical reactions, can participate in electrochemical reactions as electrolyte solutions, can make new batteries and so on. It is generally believed that ILs are not volatile and their vaporization enthalpies cannot be measured. However, in recent years, the related research results of ILs have been reviewed, and it has been found that researchers have successively proposed many methods for obtaining vaporization enthalpies of ILs. We will systematically introduce these methods, expounding their principles, and laying a solid foundation for future research.

    Nano-interface enhanced CO2 absorption and mechanism analysis
    Xiaohua LU, Yifeng CHEN, Yihui DONG, Xiaoyan JI, Wenlong XIE, Nanhua WU, Rong AN, Zhongyang DAI, Zheng LI
    2020, 71(1):  34-42.  doi:10.11949/0438-1157.20191227
    Abstract ( 560 )   HTML ( 36)   PDF (1813KB) ( 338 )  
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    CO2 capture and separation (CCS) is a key step to mitigate greenhouse gas emissions and develop renewable energy. The trade-off between the rate and efficiency in the CO2 separation process cannot be solved with the traditional process intensification. Using nano-interface to realize process intensification has been widely used in the chemical process with multi-phase transfer, and CO2 separation is one of examples. This review summarizes the research work from the establishment of CO2 transfer model at nano-interface and the resistance regulation, the acquisition of the CO2 chemical potentials at equilibrium and at the nano-interface (the driving force regulation) and the molecular simulation analysis of the interface enhancement mechanism. Based on the theoretical studies, the resistance distribution for the CO2 separation process in a real absorption tower is further analyzed and a “three-stage strengthening scheme” is proposed to decrease the investment and operating costs.

    Polymeric microneedle arrays for applications in transdermal drug delivery systems
    Xingqun PU, Xiaojie JU, Rui XIE, Wei WANG, Zhuang LIU, Liangyin CHU
    2020, 71(1):  43-53.  doi:10.11949/0438-1157.20191175
    Abstract ( 738 )   HTML ( 13)   PDF (1675KB) ( 603 )  
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    Microneedle arrays, which can avoid the barrier effect of the stratum corneum and enhance the permeability across skin for hydrophilic drugs and biological macromolecules, are a novel model for transdermal drug delivery. Microneedle arrays have been widely studied because they are featured with painless, minimally invasive and efficient properties. There are many polymeric materials and manufacturing methods for polymeric microneedle arrays; therefore, the polymeric microneedle arrays not only have the advantages of other microneedle arrays, but also have the advantages of good biocompatibility, safety, accurate and controllable drug loading and low cost, etc. The polymeric microneedle arrays are the most widely studied and most promising microneedle arrays. This paper systematically reviews the main preparation methods of polymer array microneedles and the latest research progress in transdermal drug delivery systems.

    Progress in research on channel microenvironment regulation of graphene-based CO2 separation membrane
    Peng ZHANG,Zan CHEN,Hong WU,Runnan ZHANG,Leixin YANG,Xinda YOU,Ke AN,Zhongyi JIANG
    2020, 71(1):  54-67.  doi:10.11949/0438-1157.20191376
    Abstract ( 456 )   HTML ( 25)   PDF (1652KB) ( 571 )  
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    Graphene, as a two-dimensional nanosheet with the thickness of monoatomic layer, has become a unit of high-performance carbon capture membranes due to its unique physical property. The ultrathin thickness of graphene-based membranes is conducive to the preparation of ultrathin membranes in order to improve the flux of separation membranes. Upon that, the adjustable physicochemical property endows multiple microenvironment within the two-dimensional channel of graphene. In view of the multiple mass transfer mechaisms of CO2 separation membranes, it highlights the strategies and progress of precision controllable of physiochemical microenviroment within the two-dimensional channel of graphene in recent years. Expecting to provide a clear thinking for the reasonable design and controllable equipment of graphene-based CO2 separation membranes.

    Information transfer and transformation in bio/biomimetic-mineralization
    Haihua PAN, Ruikang TANG
    2020, 71(1):  68-80.  doi:10.11949/0438-1157.20191225
    Abstract ( 573 )   HTML ( 14)   PDF (1461KB) ( 342 )  
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    Biominerals, such as teeth, bones and shells, have multi-level ordered structure and excellent mechanical properties, and are the crystallization products of mineralization under the control of biomineralization process. The strategies for the control of crystallization in biomineralization would be good examples for a better understanding of the process control and the molecular engineering in chemical engineering. Taking the bio/biomimetic-mineralization of calcium phosphate and calcium carbonate systems as an example, the fundamental principles of biomineralization, such as biominerals/solution interface, the molecular recognitions between biominerals and biomatrix, the advanced molecular control of crystallization and biomimetic fabrications of biominerals-liked hybrid materials are reviewed and discussed in view of the paradigm of“the information transfer and transformation”in chemical engineering, which would be of great helpful for the future development of chemical engineering for solving the global problems of the exponential increased demand in water, energy and commodities with limited resources by using the green and high efficiency biomineralization technology.

    Recent advances in thermodynamic modelling of ionic liquid solutions
    Chunxi LI
    2020, 71(1):  81-91.  doi:10.11949/0438-1157.20191184
    Abstract ( 736 )   HTML ( 27)   PDF (630KB) ( 419 )  
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    Ionic liquids (ILs) is a novel and green solvent, and shows prospective applications in ILs related reaction and separation processes. Their thermodynamic properties and fluid phase equilibria data are instrumental for the ILs-related process design. This paper reviewed the recent advances in thermodynamic modelling of ILs solutions in terms of the following aspects, viz. study methods of solution thermodynamics, construction of solution thermodynamic models, the structure and intermolecular forces of ILs, thermodynamic models of ILs solution and their applications in fluid phase equilibria. Special focuse was given to the development of equation of state and excess Gibbs free energy or activity coefficient models, electrolyte and non-electrolyte solution models, as well as their treatment for ILs structure, hydrogen bonding and electrostatic interactions. The merits and demerits of these models were analyzed, and some suggestions were proposed for the study of molecular thermodynamic models of ILs solutions.

    Progress on ionic liquids for gas drying
    Chengmin GUI, Ruisong ZHU, Jie ZHANG, Zhigang LEI
    2020, 71(1):  92-105.  doi:10.11949/0438-1157.20191176
    Abstract ( 497 )   HTML ( 23)   PDF (3017KB) ( 325 )  
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    Ionic liquids (ILs) are regarded as excellent substitutes for traditional solvents in chemical industry. When they are used for capturing condensable gases, they have the advantages of less solvent loss, no corrosion and strong stability. Some ILs have the strong water absorption power, thus receiving wide attention in the field of gas drying. This review introduces the predictive molecular thermodynamic model for predicting the solubility of gases in ILs and the experimental measurement method on gas solubility. The drying mechanism and process of ILs for CH4, CO2 and other gases were analyzed. Finally, the basic research of ILs for gas drying is prospected.

    Application of deep eutectic solvents in battery and electrocatalysis
    Yu CHEN, Tiancheng MU
    2020, 71(1):  106-121.  doi:10.11949/0438-1157.20191071
    Abstract ( 1341 )   HTML ( 34)   PDF (1698KB) ( 1268 )  
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    Green and efficient battery and electrocatalytic reactions are essential requirements for sustainable development. Green and sustainable development is deemed as the demands of the new age, thus green battery and green electrocatalysis is urgently required. Achieving green and efficient battery and electrocatalytic reaction is a fundamental requirement for green chemistry and sustainable development. One of the key factors is the selection of electrolytes with high efficiency and the selection of solvents for synthesizing efficient electrode materials. Previous study mainly focused on the utilization of volatile organic compounds (VOCs) and ionic liquids. However, the high volatility of VOCs would lead to high air pollution and thus endanger human health; the high price, high instability and complex synthesizing procedure of ionic liquids would also hinder the wide application of ionic liquids. Deep eutectic solvents (DESs) are new type of green electrolytes and solvents. Compared with traditional solvents and electrolytes (such as ionic liquids, water, and supercritical carbon dioxide), DESs have the advantages of simple synthesis, low price, high biocompatibility, and high designability. Therefore, DESs have great application prospects in the field of battery and electrocatalysis. However, there is not a large amount of literature reports or a review of systematical conclusion. It is necessary to review the field of DESs application in battery and electrocatalytic reaction. The contents of this review include (1) DESs as green electrolytes for batteries and electrocatalytic reaction, which includes solar cells, flow redox cell, lithium ion battery, aluminum battery, sodium battery, zinc battery, supercapacitor, carbon dioxide electroreduction, nitrogen electrocatalysis, oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, water splitting reaction and ethanol electrochemical oxidation; (2) DESs for preparation electrode materials in battery and electrocatalytic reaction; (3) DESs as a solvent for recycling electrode materials; (4) Outlook and related issues. This review would be helpful to design new types of DESs for achieving efficient and green battery and electrocatalysis.

    Recent developments in enzymatic reactive distillation coupling technology
    Qinglian WANG, Xiaoda WANG, Hongxing WANG, Zhixian HUANG, Changshen YE, Ting QIU
    2020, 71(1):  122-137.  doi:10.11949/0438-1157.20191232
    Abstract ( 538 )   HTML ( 16)   PDF (1993KB) ( 520 )  
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    Enzymatic reactive distillation which combines the enzyme-catalyzed reaction with distillation process can be used to break the limitation of reaction equilibrium and improve the conversion and selectivity effectively. It is a new process intensification technology. In this paper, the progress of enzymatic reactive distillation coupling technology is reviewed from the enzyme catalyst and its catalytic reaction mechanism, the packing method of enzyme catalyst, the coupling mode of enzyme reaction and distillation process and several application cases. It shows that current development of enzyme reactive distillation coupling technique is not mature. The enzyme-catalyzed reactive distillation is quite different with the reactive distillation catalyzed by chemical catalyst. And the influences of parameters such as reaction temperature, substrate concentration on enzyme catalytic activity should be considered. In the future, the strengthening research can be carried out from the research system, enzyme immobilization technology, enzyme catalyst loading mode, enzyme reactive distillation theory research, enzyme reactive distillation coupling process development and so on.

    Progress on carbon monoxide removal using ionic liquids
    Jiajia LIU, Xue FU, Yingjie XU
    2020, 71(1):  138-147.  doi:10.11949/0438-1157.20191208
    Abstract ( 660 )   HTML ( 24)   PDF (616KB) ( 549 )  
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    As a new type of green solvent, ionic liquids (ILs) have shown unique properties and potential application value in carbon monoxide (CO) absorption and separation. In this paper, the recent research progress of CO absorption and separation by ILs has been reviewed, including the traditional ILs, anion functionalized ILs, ILs/ Cu(Ⅰ) salts and supported IL membranes (SILMs). The solubility of CO in ILs and the selectivity to other gases are mainly discussed, which is compared to the performance of carbon dioxide (CO2) absorption by ILs. The effect of the type of anion, cation, and substituent, temperature and pressure on the ability of CO absorption and separation by ILs was summarized, and the mechanism of CO absorption by ILs was introduced. Finally, some suggestions on the design and synthesis of new functional ILs for the efficient absorption and separation of CO are put forward.

    Advances in computer simulation of graphene biotoxicity
    Mengdi ZHOU, Jiawei SHEN, Lijun LIANG, Jiachen LI, Lehong JIN, Qi WANG
    2020, 71(1):  148-165.  doi:10.11949/0438-1157.20191233
    Abstract ( 523 )   HTML ( 9)   PDF (5724KB) ( 340 )  
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    Graphene is a two-dimensional carbon nanomaterial densely packed into a two-dimensional honeycomb lattice by a flat single-layer carbon atom. Graphene has excellent optical, electrical and mechanical properties and has important application prospects in biomedicine and materials science. With the wide application of graphene in scientific research, its biosafety issues are also received huge attention. Although a large number of studies have shown that graphene has good biocompatibility, some studies have found that graphene has certain biological toxicity. Graphene could interact with proteins, lipids and nucleic acids etc. Because it could permeate through the skin due to its small particle size. Recently, computer simulation has been widely used in the field of biology, chemistry and pharmaceutics etc. due to its low cost, high safety and easy access to dynamic structures which cannot be directly obtained by available experiment technologies. Therefore, in this paper, the computer simulation of the biotoxicity of graphene to cell membrane, proteins and DNA were reviewed, which may provide a reference for graphene biosafety evaluation and biomedical applications.

    Computer-aided method for catalytic reaction engineering research & process development
    Ming XIA, Congcong NIU, Hui SHI, Wei ZHANG, Zhongyi MA, Congbiao CHEN, Litao JIA, Bo HOU, Debao LI
    2020, 71(1):  166-176.  doi:10.11949/0438-1157.20191334
    Abstract ( 574 )   HTML ( 19)   PDF (933KB) ( 447 )  
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    Focusing on the problems in science, technology and engineering of catalytic reaction kinetic, catalyst particle engineering design, reactor analysis and process systems development, this work extended a computer-aided method for catalytic reaction engineering research and process development on the basis of the development work blocks established by the former ministry of chemical industry of China and the development requirements of high-technology institute s research and development. The extended method stressed the importance of computer-aided simulation in the multi-scale research and development, aiming to shorten research and development cycle and ensure high-efficient project implementation. At the same time, the related developments of catalytic reaction engineering research and process system development are reviewed, discussed and prospected.

    Thermodynamics
    Densities and viscosities of binary system containing 1,3-dimethylimidazolium dimethylphosphate and dimethyl sulfoxide or acetonitrile
    Xinxin WANG, Qing ZHOU, Xiaochun ZHANG, Zhibo ZHANG, Xingmei LYU, Suojiang ZHANG
    2020, 71(1):  177-191.  doi:10.11949/0438-1157.20191361
    Abstract ( 720 )   HTML ( 17)   PDF (2669KB) ( 185 )  
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    Due to its special structure and properties, ionic liquids have shown good results in the application of cellulose pretreatment. Relevant physical property data is indispensable in promoting the industrialization of ionic liquids. In this study, ionic liquid 1, 3-dimethylimidazolium dimethylphosphate ([Mmim][DMP]) was synthesized and the densities and viscosities for the binary systems of [Mmim][DMP] with dimethylsulfoxide (DMSO) or acetonitrile were measured in the temperature range from (293.15 to 323.15) K over the whole concentration. Then volume properties and excess property data was calculated and fitted. Based on the data of apparent molar volume V ? , apparent molar volume at infinite dilution V ? , partial molar volume V ? , excess molar volume V E, and molecular simulation results, the influence of the interaction between IL and solvents and hydrogen bonds formed between IL and DMSO (or acetonitrile) were analyzed.

    Theoretical investigation on thermodynamic properties of group Ⅲ phosphides
    Jie WU, Jiahui LI, Yanmei YU, Yangxin YU
    2020, 71(1):  192-199.  doi:10.11949/0438-1157.20191229
    Abstract ( 392 )   HTML ( 14)   PDF (1001KB) ( 408 )  
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    Group Ⅲ phosphides are one kind of important semiconductors, and the prediction of their thermodynamic properties is a basis of the design and application of these materials. Within the framework of density functional theory and the phonon model, the structural and thermodynamic properties as well as thermal expansion coefficients of boron phosphide, aluminum phosphide, gallium phosphide and indium phosphide were systematically investigated in the temperature range of 0—1000 K. The calculated lattice parameters for group Ⅲ phosphides are in good agreement with available experimental and other calculation results. It was also found by anharmonic approximation that the thermodynamic properties such as enthalpy, entropy and coefficient of thermal expansion increase monotonously with the increase of temperature, while the heat capacity approaches the Dulong-Petit limit at high temperatures (>700 K). The calculated values are in consistence with available experimental data, indicating that the used theoretical method is reliable for the prediction of thermodynamic properties of these semiconductors.

    Development of group-contribution equation of state and theoretical prediction of thermodynamic model parameters
    Shaoguang QU, Changhao WANG, Yunhai SHI, Changjun PENG, Honglai LIU, Ying HU
    2020, 71(1):  200-208.  doi:10.11949/0438-1157.20191149
    Abstract ( 523 )   HTML ( 12)   PDF (586KB) ( 327 )  
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    Thermodynamic model is an important tool to study fluid phase behaviour and thermodynamic properties.The effective application of theoretical model is inseparable from the determination of model parameters. To endow the prediction function of the thermodynamic model, the current strategy is to establish the group contribution(GC) equation of state(EOS), and to explore the theoretical prediction method of the parameters of the thermodynamic model. Based on the previously developed equations of state for square-well chain fluids with variable well-width range(GC-SWCF-VR ), the group contribution equations of state for square-well chain fluids(GC-SWCF) were established, and the contribution values of different groups to model parameters were obtained by using group contribution method. It was proved that the density of pure substences can be predicted satisfactorily by GC-SWCF. Combining conductor-like screening model(COSMO) with SWCF, the model parameters of SWCF equation for 192 organic compounds were obtained based on COSMO method, which is a theoretical method to determine model parameters without relying on experimental data. It is found that COSMO+SWCF can predict the density of pure substences. Using one temperature-independent binary interaction adjustable parameter, both GC-SWCF and COSMO+SWCF can be applied to the calculation of densities and vapor-liquid equilibrium for binary mixture.

    Phase equilibria of quaternary system CaCl2-CaSO4-CaB6O10-H2O at 308.15 K
    Fei YUAN, Jiangtao SONG, Jiayin HU, Yafei GUO, Shiqiang WANG, Tianlong DENG
    2020, 71(1):  209-215.  doi:10.11949/0438-1157.20191148
    Abstract ( 470 )   HTML ( 8)   PDF (749KB) ( 129 )  
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    In this work, an isothermal dissolution method was used to study the phase equilibria for the quaternary system (CaCl2-CaSO4-CaB6O10-H2O) at 308.15 K. The solubilities, densities, refractive indices and pH were investigated experimentally. According to the experimental data, the phase diagram, water-phase diagram and the diagrams on physicochemical properties including density, refractive index and pH against composition were plotted. The phase diagrams for the quaternary system at 308.15 K include one invariant point, three univariate solubility curves and three crystalline regions corresponding to CaCl2·4H2O, gypsum (CaSO4·2H2O) and gowerite (CaB6O10·5H2O). The crystallizing area of gypsum (CaSO4·2H2O) is the largest, the gowerite (CaB6O10·5H2O) is the second, and the CaCl2·4H2O is the smallest, indicating that the gypsum is most easily crystallized. In addition, the quaternary system was of the hydrate type I, neither double salt nor solid solution were formed. The physicochemical properties change regularly with the increasing of CaCl2 concentration and appeared a turning point at invariant point. The distributive behaviors of density and refractive index against the concentration of calcium chloride in the equilibrium solution are similar. On the contrary, the change law of pH is opposite. The phase equilibrium study of quaternary system (CaCl2-CaSO4-CaB6O10-H2O) will provide a theoretical basis for the development and utilization of calcium and boron resources in oilfield brines.

    Experimental and theoretical studies on vapor liquid equilibrium for formaldehyde + 1,3,5-trioxane + sulphuric acid + water system
    Xianming ZHANG, Yufeng HU
    2020, 71(1):  216-224.  doi:10.11949/0438-1157.20191242
    Abstract ( 501 )   HTML ( 4)   PDF (650KB) ( 179 )  
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    1,3,5-Trioxane is industrially produced from aqueous formaldehyde solutions through reaction distillation catalyzed by sulfuric acid. Optimizing industrial process of the synthesis and developing new catalysts have attracted extensive attention. It is necessary to establish a vapor-liquid equilibrium model of the reaction system and reveal the multiple functions that the catalyst may play in the synthesis of 1,3,5-trioxane. For this reason, experimental data for the vapor-liquid equilibrium of (formaldehyde + 1,3,5-trioxane + H2SO4 + water) system are measured. The extended UNIFAC model is used for correlating the vapor-liquid equilibrium data, and the model parameters are determined, whereby systematic calculation is made. The results show that the sulfuric acid catalyst has triple functions in the reaction distillation process. The above results are of great significance for optimizing the production process of 1,3,5-trioxane and developing new catalysts.

    Vapor-liquid equilibrium measurement featuring vapor phase sampling and synthetic liquid composition for systems containing ionic liquids
    Yalong TAN, Gaoxiang SHU, Linfang CUI, Lianzhong ZHANG
    2020, 71(1):  225-230.  doi:10.11949/0438-1157.20191316
    Abstract ( 416 )   HTML ( 7)   PDF (482KB) ( 165 )  
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    With respect to the application of ionic liquids in extractive distillation, this paper deals with some details of a synthetic method for liquid phase composition, while the vapor phase sample is analyzed, for the measurement of vapor-liquid equilibrium for systems containing ionic liquids. Basic ideas were from the quasi-static method, the exchanging method, and a structure of boiler featuring the active supply of vaporization center, which were developed by the research group of Prof. Shijun Han. Modified structures were presented for the droplet circulation of vapor phase and the boiler. A calculational procedure was presented for the liquid phase composition for systems containing several volatile and non-volatile components. Estimation of uncertainties was also presented. The method proposed provides experimental results for activity coefficients of the volatile components without the need of the relatively complicated analysis of the liquid phase sample containing ionic liquids. Through a procedure of repeated synthesis, trend of activity coefficients can be obtained with the variation of the composition. The method can be used for evaluation and screening of solvents for extractive distillation.

    Determination of solubility of steviol glycoside and rebiana as natural sweeteners in different solvents
    Hao YAN, Weidong YAN
    2020, 71(1):  231-236.  doi:10.11949/0438-1157.20191341
    Abstract ( 532 )   HTML ( 18)   PDF (727KB) ( 354 )  
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    The solid-liquid equilibrium data of two natural sweeteners, stevioside and rebiana, in different pure solvents were determined by high performance liquid chromatography (HPLC) at a temperature range of 288.15—328.15 K. From the experimental data, it was found that the solubility increased with the rising temperature in all studied solvents. The obtained values for the solubility of steviol glycoside and rebiana in pure solvents were correlated with the three-parameter equation and NRTL models. The results showed that two models can accurately correlate the solubility data obtained in this work. According to the solubility data obtained, the separation of steviol glycoside and rebiana and the selection of solvent for crystallization and purification are guided. According to the solubility data obtained, the separation of steviol glycoside and rebiana and the selection of solvent for crystallization and purification are guided.

    Retrofit for lubricating furfural refining process based on phase diagram analysis
    Jianqing HU, Kan WANG, Bingjian ZHANG, Qinglin CHEN
    2020, 71(1):  237-244.  doi:10.11949/0438-1157.20191304
    Abstract ( 576 )   HTML ( 10)   PDF (929KB) ( 211 )  
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    This paper is focused on improving the quality of the extracted oil and the yield of raffinate oil in the furfural process. Retrofit scheme for furfural refining process is proposed, figuring out the low separation efficiency of saturated and aromatic components. Adopting the virtual component method, the lubricating oil components are simplified into saturated, aromatic and polar component. The NRTL model is employed to predict the liquid phase equilibrium data at various temperature. With the analysis of temperature and solvent, the phase equilibrium temperature is the key point to affect the composition of liquid-liquid equilibrium and mass transfer efficiency. Based on the analysis of extraction process by phase diagram, a multi-stage extraction liquid recovery system for separating the extracted oil by temperature reduction step was proposed, resolving the difficulty of operating at lower temperatures. The simulation calculation was carried out in combination with the practical furfural refining unit. The results showed that designing a multi-stage extraction liquid recovery system,the solvent ratio, the heat and cold utility in the extraction process increased slightly. However, the yield of the raffinate oil is increased by more than 10%, and the quality of extracted oil is significantly improved. The separation efficiency in lubricating furfural refining is greatly improved.

    Solid-liquid phase equilibrium of dipentaerythritol in three mixed solvents
    Tao LI, Jiao SHA, Rui ZHAO, Pengshuai ZHANG, Shiqi LIU, Yu LI, Baozeng REN
    2020, 71(1):  245-253.  doi:10.11949/0438-1157.20191215
    Abstract ( 563 )   HTML ( 8)   PDF (555KB) ( 228 )  
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    In this paper, by the dynamic balance method, the solubility of dipentaerythritol (DPE) in water+(Methanol, ethanol, isopropanol) mixed solvents were evaluated from 293.15 K to 332.80 K under atmospheric pressure. The results showed that the solubility of DPE in different mass fractions of water + (methanol, ethanol, isopropanol) mixed solvents increases with the increasing of temperature. At the same temperature, the solubility in the selected solvent system increases first and then decreases with the increase of the mass fraction of methanol, ethanol or isopropanol. Experimental solubility data were correlated by three thermodynamic models including λh equation, the two parameters equation and the modified Apelblat equation. All the selected models give useful result in regression analysis of solubility. By the modified van t Hoff equation, the calculated Δsol H 0, Δsol S 0 and Δsol G 0 of DPE in the selected solvent system are all positive, indicating that the dissolution process is endothermic, entropic and non spontaneous.

    Determination and estimation of interfacial tension of CO2-cycloalkanes/aromatics
    Lin LI, Shuqian XIA, Qiaoyan SHANG, Peisheng MA
    2020, 71(1):  254-264.  doi:10.11949/0438-1157.20191260
    Abstract ( 386 )   HTML ( 4)   PDF (993KB) ( 292 )  
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    CO2 enhanced oil recovery technique uses CO2 to extract the remaining oil trapped in the stratum to enhance oil recovery and achieve CO2 landfill. Since CO2 can reduce the interfacial tension of crude oil, the interfacial tension data of CO2-crude oil system is an important basic data of CO2 Enhanced Oil recovery process. In this work, the interfacial tension data of CO2-cyclopentane/cyclohexane/cyclooctane/toluene/ethylbenzene/ethylcyclohexane were measured by pendent drop method at 40—120℃ in the pressure range of 0.27—14.70 MPa. The effects of pressure, temperature, carbon number and molecular structures on interfacial tension are analyzed. The results show that the interfacial tension values decrease with the pressure increasing when the temperature is constant. And at lower pressure, interfacial tension values decrease with the temperature increasing. But at higher pressure, it shows an opposite trend. The interfacial tension values of CO2-similar morphology structure increase with the carbon number. And the intermolecular forces have a certain effect on the interfacial tension. One empirical model for the interfacial tension is presented by analyzing the influences of these factors and summarizing the experimental data of CO2-crude oil (n-alkanes, cycloalkanes, aromatic hydrocarbons) binary system. In the model, the temperature, the pressure, the carbon number and the acentric factor were considered. The square of the correlation coefficient (R 2), root mean square error (RMSE) and average relative deviation (AARD) were 0.958, 1.12, 11.01% respectively.

    Fluid dynamics and transport phenomena
    Droplet and bubble dispersion in step T-junction microchannel
    Yuchao CHEN, Yongjin CUI, Kai WANG, Guangsheng LUO
    2020, 71(1):  265-273.  doi:10.11949/0438-1157.20191214
    Abstract ( 538 )   HTML ( 26)   PDF (1635KB) ( 812 )  
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    A high-speed camera was used to study the dispersion of droplets and bubbles in a stepped T-microchannel embedded in a capillary. Effects of two-phase flow, viscosity and surfactant on the flow pattern and the size of droplet and bubble were investigated. The results show that for the droplet dispersion system, the flow pattern is determined by the concentration of the surfactant and the continuous phase flow rate. The flow pattern changes from dripping flow to jetting flow as the two factors increase. For the bubble dispersion system, only the squeezing and dripping flow patterns exist. Addition of the surfactant has almost no effect on the bubble dispersion. The droplet and bubble size could be much smaller than channel size. Mathematical models for predicting the dispersion size in different systems are established, and the models have good prediction performances.

    Development and application of image analysis method based on deep-learning in gas-liquid-solid three-phase reactor
    Zhengliang HUANG, Chao WANG, Shaoshuo LI, Yao YANG, Jingyuan SUN, Jingdai WANG, Yongrong YANG
    2020, 71(1):  274-282.  doi:10.11949/0438-1157.20191255
    Abstract ( 538 )   HTML ( 13)   PDF (1819KB) ( 352 )  
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    In gas-liquid-solid three-phase reactors, the great challenges for image detection of flow parameters have been caused by the complex background with particles. An image analysis method of gas-liquid-solid three-phase reactor based on deep-learning is developed, which includes four steps: collecting image, making training set, establishing image recognition model and extracting flow parameters. The full convolutional neural network algorithm was chosen to build the identification model, and when the learning rate was set as 0.005, the number of epochs was set as 2000 and the training set size was set as 400 images in this model, the identification error of the model is less than 5%. The flow parameters such as local phase fractions (gas fraction and liquid fraction) and its spatial distribution, time series signals were obtained by the method. Then time domain analysis, frequency analysis, wavelet analysis and other analysis methods were used to extract the quadratic parameters from the spatial distribution and time series signals. And the quadratic parameters could be used to identify flow regimes, predict pressure drop and detect the uniformity of gas-liquid distribution. Furthermore, the method was applied to the detection of flow parameters in a trickle bed. The results showed that the time-domain variation, power spectrum density and probability density distribution of liquid fractions were used to distinguish the trickle flow, pulse flow and bubble flow. Meanwhile, the flow regime boundary was detected by characteristic parameters such as mean, standard deviation, range and half-width of probability density distribution curve of liquid fractions. The pressure drop in the trickle flow regime was predicted by the average liquid fraction, and the average relative deviation between the theoretical and experimental measurements was about 15%. In addition, the standard deviation of liquid fractions in the spatial distribution was used to detect the uniformity of gas-liquid distribution of different flow regimes in the trickle bed. This method provides a new tool for the research of gas-liquid-solid three-phase reactors.

    Catalysis, kinetics and reactors
    Study on modification of titanium-based metal-organic framework and catalytic performance
    Yunpeng QU, Bingxing ZHANG, Jinbiao SHI, Xiuniang TAN, Buxing HAN, Guanying YANG, Jianling ZHANG
    2020, 71(1):  283-289.  doi:10.11949/0438-1157.20191213
    Abstract ( 599 )   HTML ( 15)   PDF (1790KB) ( 491 )  
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    A series of materials were prepared by modifying titanium based metal-organic framework material NH2-MIL-125 with hydrogen peroxide at a certain temperature. The effects of modification methods and conditions on the properties of materials were studied systematically. However, NH2-MIL-125 as a photocatalyst suffers from low catalytic activity and stability, which largely restrict its practical applications. In order to improve the catalytic activity of NH2-MIL-125, a solvothermal route by using H2O2 was used to modify NH2-MIL-125. A series of materials were synthesized by treating NH2-MIL-125 with different volumes of H2O2 at different temperatures. X-ray diffraction, scanning electron microscope, transmission electron microscope, ultraviolet-visible light absorption spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and N2 adsorption analysis were used to characterize the structures and properties of the obtained product. Furthermore, their photocatalytic performances for the visible-light-driven oxidation of benzyl alcohol were tested. The results show that the product modified by 10 ml H2O2 at 50℃ exhibits excellent catalytic activity and selectivity. The maximum turnover frequency is nearly 6 times as high as that of NH2-MIL-125 at the same experimental conditions. The partial loss of organic ligands and the introduction of peroxide groups could generate more catalytic-active sites, which is responsible for the improved catalytic activity.

    Efficient isomerization of glucose to fructose co-catalyzed with basic ionic liquid and sodium borate
    Xiaoyan XIANG, Yi WEI, Baoyou PEI, Rongxing QIU, Xiaoyan CHEN, Zhaoyang ZHAO, Xiaoyan LUO, Jinqing LIN
    2020, 71(1):  290-296.  doi:10.11949/0438-1157.20191201
    Abstract ( 473 )   HTML ( 9)   PDF (661KB) ( 306 )  
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    Carbohydrates are an important part of biomass and can be converted into a series of high value-added chemicals through catalytic conversion, which has the advantages of high economic value, environmental friendliness and sustainability. Isomerization of glucose into fructose is a key step in the process. Herein, four basic functional ionic liquids: [HOEtMim]Phen, [EMim]Phen, [HOEtMim]Im, [Ch]Phen were synthesized and their catalytic performances on glucose isomerization were investigated. A comparison of direct transformation and catalysts combined with sodium borate complex was discussed. It showed that four basic ionic liquids exhibit good catalytic activities, but fructose is easily to be further degraded. While ionic liquids added with sodium borate obtain much higher fructose yields. It indicates that sodium borate plays an important role in both protective agent and synergistic catalysis. [Ch]Phen added with sodium borate is the most efficient. The basic structure parameters of [Ch]Phen were further characterized by 1H NMR, FT-IR and TG-DTG techniques. The effects of reaction temperature, reaction time, the dosage of catalyst and sodium borate on the isomerization and the optimal reaction conditions were investigated by single factor method. The yield of fructose is up to 64.7% with a high selectivity of 73.1% under the optimum condition at 70℃ within 7 min.

    Fe-Ce/SiO2 solid base catalyst for preparing dimethyl carbonate
    Chenliang WU, Xiaoqing LI, Chao ZHANG, Hefeng ZHANG, Xinhuan YAN
    2020, 71(1):  297-305.  doi:10.11949/0438-1157.20191152
    Abstract ( 417 )   HTML ( 8)   PDF (1523KB) ( 330 )  
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    A tetravalent supported iron catalyst is prepared by chemical reduction and oxidized to a Fe3+ basic active center by air. The activity and selectivity of the catalyst in the transesterification of propylene carbonate with methanol to prepare dimethyl carbonate were evaluated. The prepared catalysts were characterized by N2 adsorption-desorption, TEM, XRD, XPS and CO2-TPD. Compared with Fe or Ce single metal catalyst, the basic amount of Fe-Ce/SiO2 catalyst is greatly improved, and the interaction between Fe and Ce formed a stable amorphous structure. Propylene carbonate conversion of 88% and dimethyl ester selectivity of 92% were reached under the reaction conditions of alcohol ester molar ratio of 15∶1, reaction temperature of 140℃, catalyst dosage of 0.5% of the total mass of the reactants, and Ce/Fe atomic ratio of 2∶1. The activity of the catalyst remained unchanged after 10 cycles of use.

    Effects of Sm addition on reactivity and thermal stability of Pt/SBA-15 for catalytic complete oxidation of benzene
    Jianxin MAO, Ziqing YUAN, Hongxiao YANG, Renxian ZHOU
    2020, 71(1):  306-313.  doi:10.11949/0438-1157.20191258
    Abstract ( 396 )   HTML ( 7)   PDF (1091KB) ( 156 )  
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    The Sm addition effects on the reactivity and thermal stability of Pt/SBA-15 for catalytic complete oxidation of benzene were investigated. A simple method for recording the burning-off curves and the evaluation for the thermal stability of catalysts was adopted, that is, a constant flow of reaction gas was continuously introduced into a fixed bed reactor loaded with catalyst. The reaction temperature was increased step by step, and the on-line outlet concentrations of benzene were detected after time interval sampling. The burning-off curves could be recorded during this stage. After that, the reaction temperature was increased continuously, and kept at a certain value (e.g. 550℃), the on-line sampling analysis was kept at a set time. If necessary, the reaction temperature could be decreased step by step to check the activity variation of the catalyst. The results indicated that the activity order for four catalysts at lower temperature stage was Pt/SBA-15≈Pt/4%Sm2O3/SBA-15> Pt/Sm2O3> 4%Sm2O3/SBA-15, while the stability order at high temperature was Pt/4%Sm2O3/SBA-15> Pt/1.2%Sm2O3/SBA-15> Pt/SBA-15,Pt/Sm-SBA-15(SG)> Pt/SBA-15(SG). In conclusion, Sm can not improve the catalytic activity of Pt / SBA-15 at low temperature, but can significantly improve the stability of the catalyst at high temperature. At the same time, 1% Pt/4% Sm2O3 / SBA-15 has good catalytic activity at low temperature and high temperature stability, and has a good application prospect.

    Study on catalytic properties of novel ether-based perrhenate ionic liquids
    Xiaoxue MA, Kunhao LIANG, Jie WEI, Zongren SONG, Chuanyou XIAO, Lu GONG, Dawei FANG
    2020, 71(1):  314-319.  doi:10.11949/0438-1157.20191367
    Abstract ( 365 )   HTML ( 5)   PDF (675KB) ( 129 )  
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    Two novel ether-based perrhenate ionic liquids 1-(2-methoxyethyl)-3-ethylimidazolium perrhenate ([C22O1Im][ReO4]) and1-(2-ethoxyethyl)-3-ethylimidazolium perrhenate ([C22O2Im][ReO4]) were synthesized and characterized by nuclear magnetic resonance spectroscopy (1H NMR,13C NMR), Raman spectroscopy (Raman), electrospray ionization mass spectrometry (ESI-MS), differential scanning calorimetry (DSC). As a sort of organic synthesis intermediates which is chemically active and easily converted into other substances, epoxy compounds occupy an extremely important position in various industries of national production. The epoxidation of olefins is an important way to synthesize epoxy compounds. Therefore, two novel ether-based perrhenate ionic liquids were used as catalyst and solvent in the reaction system of cyclooctene epoxidation to epoxycyclooctane, respectively. The effects of reaction temperature, time, oxidant amount, catalyst amount and its recycle were investigated systematically. The results showed that the yield was more than 90%, the reaction selectivity was more than 99%, the catalyst was cycled 5 times, and the yield did not decrease significantly.

    Separation engineering
    Study on efficient separation of SF6/N2 mixture using a hydrothermally stable metal-organic framework
    Miao CHANG, Lei LIU, Qingyuan YANG, Dahuan LIU, Chongli ZHONG
    2020, 71(1):  320-328.  doi:10.11949/0438-1157.20191133
    Abstract ( 555 )   HTML ( 13)   PDF (1338KB) ( 382 )  
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    The efficient separation of the SF6/N2 mixture has important practical significance for the recovery of SF6 gas and the reduction of the greenhouse effect caused by its direct discharge. In this work, a metal–organic framework (Cu-MOF-OMe) was prepared with two different types and properties of pores. It possesses dually-functionalized characteristics of coordinatively unsaturated metal sites and methoxy groups, which exhibit good hydrothermal stability and adsorptive regenerability. This material also shows excellent separation performance for SF6/N2 mixture. At 298 K and 105 Pa, the observed adsorption selectivity (361) and sorbent selection parameter (SSP) value (780) are highest compared to various porous materials reported so far. Theoretical calculation results indicated that the underlying reason of such excellent separation properties is attributed to the cooperative effects of the open Cu sites in the hydrophilic pores and the abundant methoxy groups in the hydrophobic pores. The findings may provide valuable foundation for developing highly efficient materials for practical of SF6/N2 separation.

    Optimized fabrication of mixed matrix membranes based on amino-MIL-101(Cr) for highly efficient CO2 separation
    Kai YANG, Xuehua RUAN, Yan DAI, Jiaming WANG, Gaohong HE
    2020, 71(1):  329-336.  doi:10.11949/0438-1157.20191283
    Abstract ( 605 )   HTML ( 18)   PDF (1235KB) ( 230 )  
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    Metal-organic framework MIL-101(Cr) is a kind of new membrane materials with large pore size and high porosity, which can greatly enhance CO2 permeability for mixed matrix membranes. However, the blending with MIL-101(Cr) particles will lead to obvious decrease in CO2 selectivity, mainly caused by the following two reasons: terephthalic acid, as organic legend in MIL-101(Cr), is low in CO2 affinity relatively; particles after drying for activation, unable to be adequately dispersed in casting solution, would form defects in membranes. In response, two innovative attempts were carried through in this work. At first, amino-MIL-101(Cr) fillers were synthesized with 2-amino-terephthalic acid as organic legend, which could increase solution selectivity. Secondly, the retrofitted technique with MIL-101(Cr) activation after membrane fabrication was utilized to decrease defects caused by particle aggregation. FI-TR characterization revealed that amino-MIL-101(Cr) particles have been synthesized successfully. SEM images demonstrated that both MIL-101(Cr) and amino-MIL-101(Cr) particles can be evenly distributed in mixed matrix membranes through the retrofitted technique. Afterward, the membranes were fabricated with amino-MIL-101(Cr) blended in ethyl cellulose. Gas permeation tests revealed that the optimum particle loading is around 15%(mass). In this case, P C O 2 is about 166 barrer (16.5% and 93.0% higher than MIL-101(Cr) blended and pristine membranes, respectively), while α C O 2 / N 2 is about 23.9 (25.3% and 17.1% higher than that of MIL-101(Cr) blended and pristine membranes, respectively). On the whole, the blending with amino-MIL-101(Cr) particles through casting-activation approach can significantly enhance CO2 selective permeation in mixed matrix membranes.

    Study on synthesis and adsorption performance of hydrophobic ZSM-5 zeolites for removal of toluene in high-humidity exhaust gas
    Jun an GAO, Wei WANG, Jie ZHANG, Zhigang LEI, Dongjun SHI, Lingduo QU
    2020, 71(1):  337-343.  doi:10.11949/0438-1157.20191253
    Abstract ( 507 )   HTML ( 9)   PDF (972KB) ( 395 )  
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    ZSM-5 zeolites with different Si/Al ratios were synthesized by hydrothermal in situ method. The effect of Si/Al ratio on the structure and hydrophobicity of ZSM-5 was studied. The adsorption performance of ZSM-5 zeolites for toluene was investigated on a dynamic adsorption experimental device, and the adsorption isotherm equation of toluene on hydrophobic ZSM-5 was studied. The results show that the high-silicon ZSM-5 has good hydrophobicity, and its static water adsorption capacity is 0.014 g·g-1. Under high humidity conditions, the toluene concentration of 1800 mg·m-3, the GHSV of 25000 ml·h-1·g-1 and the temperature of 35℃, the breakthrough adsorption capacity of the synthesized ZSM-5 for toluene is 0.041 g·g-1, and the toluene saturated adsorption capacity is 0.075 g·g-1. The fitting of the adsorption isotherm showed that the adsorption of toluene on the hydrophobic ZSM-5 zeolites was in accordance with the Langmuir-Freundlich model.

    Biochemical engineering and technology
    Molecular dynamics study of binding of isoquinoline alkaloids to G-quadruplex
    Bo ZHANG, Yiran HE, Yingchun LIU, Qi WANG
    2020, 71(1):  344-353.  doi:10.11949/0438-1157.20191265
    Abstract ( 458 )   HTML ( 11)   PDF (1700KB) ( 127 )  
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    G-quadruplex is a nonclassical secondary structure of nucleic acids, which is mainly found in guanine (G) - rich DNA or RNA sequences. The G-quadruplex in organism is mainly formed in the telomere region and the promoter region of some proto-oncogenes, which is an essential object of biomedical research. Although the anti-cancer strategy targeting G-quadruplex has been proposed many times, no successful clinical trials have been conducted so far. Therefore, the study of G-quadruplex ligand binding in the proto-oncogene promoter region can provide guiding suggestions for the design of targeted anti-cancer drugs. The binding mechanism of different isoquinoline alkaloids to G-quadruplex was studied by molecular dynamics simulation. The confirmation of the stable binding of four isoquinoline ligands to G-quadruplex and the dominant factors of the binding were obtained by studying the binding process of the four isoquinoline ligands to G-quadruplex. This work has deepened the microscopic understanding of the binding mechanism of isoquinoline alkaloids and G-quadruplex at the atomic and molecular level and has guiding significance for the design of anti-cancer drugs.

    Molecular simulation on doxorubicin encapsulation and transport by chitosan-boron nitride nanotubes
    Jiachen LI, Bin YU, Qi WANG, Li ZHANG
    2020, 71(1):  354-360.  doi:10.11949/0438-1157.20191226
    Abstract ( 341 )   HTML ( 10)   PDF (817KB) ( 381 )  
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    There is a potential application prospect of chitosan BNNTs composite carrier in the field of drug transport. It is important to understand the mechanism of the encapsulation and transport of drugs by chitosan-BNNTs from atomic level. Herein, molecular dynamics (MD) simulation was employed to investigate the process of encapsulation and transmembrane delivery of doxorubicin (DOX) by chitosan-BNNTs. The anticancer drug DOX was used as a drug model. The free energy results indicate that DOX and chitosan can spontaneously enter the tube. It is also found that DOX can be adsorbed by the non-protonated chitosan and enter the tube in a suitable conformation. The interaction energy results show that phospholipid molecules can embed into BNNT (14,14) tubes, and extrude chitosan and DOX in the tube. This study can provide ideas for experiments to improve drug encapsulation efficiency and increase drug concentration on cancer cells.

    Energy and environmental engineering
    Efficient SO2 capture by ether-containing anion-functionalized ionic liquids
    Qiaoxin XIAO, Wenjun LIN, Haoran LI, Congmin WANG
    2020, 71(1):  361-367.  doi:10.11949/0438-1157.20191261
    Abstract ( 400 )   HTML ( 7)   PDF (748KB) ( 196 )  
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    The development of high efficient, economic and green SO2 absorbers not only has a strong academic value, but also has a good application prospect. Herein, a series of ether-containing anion-functionalized ionic liquids were designed and prepared. The effect of ether on SO2 absorption was investigated. The results indicated that SO2 capacity increased significantly when ether was introduced on the anion. Furthermore, absorption capacity of SO2 did not decrease obviously when the cation with a smaller molar mass tributyl ethyl phosphorus [P4442] was used. The effective absorption capacity of [P4442][2-CH3OPhCOO] was 3.32 mol SO2 per 1 mol IL at 20℃ and 105 Pa, with the effective mass absorption of 0.56 g SO2 per 1 g IL. The cycles of six absorption and desorption showed that SO2 capture by [P4442][2-CH3OPhCOO] was efficient and reversible. The method introducing ether to improve gas capture may be useful for other fields such as separation, catalyst and so on.

    Study on the capture of low pressure SO2 by imidazole-based ternary deep eutectic solvents
    Xiaoxia DENG, Lei GONG, Xiaobang LIU, Dongshun DENG
    2020, 71(1):  368-375.  doi:10.11949/0438-1157.20191266
    Abstract ( 469 )   HTML ( 3)   PDF (623KB) ( 151 )  
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    In recent years, DESs, which is composed of hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), is considered as a potential SO2 adsorbent due to its properties similar to ionic liquids. To prepare the DESs with large absorption capacity for low pressure SO2, reasonable price and good recycling performance, three ternary functionalized DESs of CC-Gly-Im, CC-PEG200-Im, CC-EG-Im were developed using choline chloride (CC) as HBA, imidazole (Im) as functional component, and cheap glycerol (Gly), PEG200, ethylene glycol (EG) as second HBD. The obtained DESs were further applied for experimental study for low pressure SO2, focusing on the type of second HBD, the content of imidazole, and temperature on the absorption performance of SO2. The results showed that PEG200 demonstrated the best property, and its DESs possessed moderate density and viscosity, satisfactory thermal stability and absorption capacity. The maximum absorption of CC-PEG200-Im (1∶2∶7) DESs for 1% SO2 at 40℃ reached 0.236 g SO2/g DES. The DESs presented stable absorption performance for SO2 after five absorption-desorption cycles. The CC-PEG200-Im could absorb SO2 by chemical interactions at the experimental conditions under 1H NMR spectrum investigation.

    Material science and engineering, nanotechnology
    Effect of Mg2+ on structure and physical chemistry properties of PVA/GG-Mg2+ composite hydrogels
    Fei WANG, Tongchun BAI
    2020, 71(1):  376-387.  doi:10.11949/0438-1157.20191330
    Abstract ( 413 )   HTML ( 4)   PDF (2008KB) ( 351 )  
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    The composite hydrogels of polyvinyl alcohol (PVA) and gellan gum (GG) are of interesting in the biomaterials application for its better biocompatibility. To improve the structure and mechanical properties of hydrogels, in this work, Mg2+ was introduced to crosslink the polymer chain, and the PVA/GG-Mg2+ hydrogel was formed. By analyzing its network structure, mechanical properties, swelling and dehydration kinetics, the effect of Mg2+ on the molecular interaction, hydrogel network structure and physical properties have been observed. The result indicates that, Mg2+ plays an important role in PVA/GG-Mg2+ hydrogel, it reorganizes the network structure, enhances the mechanical properties, strengthens the electrolytic and hydrogen bonding interactions, and improves the water holding property. The effect of the interaction between GG and Mg2+ is similar to the composite hydrogels of PVA/GG-Ca2+ and PVA/GG-Al3+. These observations will help the development of composite hydrogels in biomaterials application.

    Microstructure characterization and thermal stability of new silk fibroin composite films
    Yingying LI, Qianqian DENG, Hao LIU, Qichun LIU, Zhenggui GU, Fang WANG
    2020, 71(1):  388-396.  doi:10.11949/0438-1157.20191317
    Abstract ( 439 )   HTML ( 2)   PDF (996KB) ( 752 )  
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    Silk fibroin-based polymer composites can be widely used in the fields of tissue engineering, biomedicine, and semiconductor materials. In this study, a novel silk fibroin/polylactic acid biocomposite film was prepared by physical-blending technique. Scanning electron microscope(SEM), Fourier transform infrared analysis(FTIR), Raman spectroscopy, X-ray diffraction (XRD) and thermal analysis were used to characterize the morphology, structure, phase components and thermal stability of the composite films with different proportions, and to explore their microstructure, interaction mechanism and thermal stability. The results showed that with the increase of silk fibroin content, the content of β-sheet increased, the content of α-helix and random coils decreased, and the glass transition temperature increased. Due to the interaction between silk fibroin and polylactic acid, which improved the thermal stability of the composite film.

    g-C3N4-CdS-NiS2 composite nanotube: synthesis and its photocatalytic activity for H2 generation under visible light
    Kelong CHEN, Jianhua HUANG
    2020, 71(1):  397-408.  doi:10.11949/0438-1157.20191249
    Abstract ( 575 )   HTML ( 4)   PDF (2402KB) ( 661 )  
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    Rapid recombination of photogenerated electron-hole pairs is one of important factors leading to poor performance of semiconductor photocatalysts. Constructing a heterojunction is an effective method for separation of photogenerated electron-hole pairs. In the present work, g-C3N4-CdS-NiS2 composite nanotube was synthesized via thermal condensation using urea and thiourea as precursors, and subsequent two-step hydrothermal reactions. The photocatalytic activity of g-C3N4-CdS-NiS2 composite was investigated for H2 generation from water using triethanolamine as sacrificial agent under visible light irradiation. The optimal g-C3N4-CdS-NiS2 composite with the content of CdS 10%(mass) produced H2 at a rate of 50.9 μmol·h-1, which is 25 times and 11 times of that of pure g-C3N4 nanotube and g-C3N4-CdS (NiS2) binary composite, respectively. Moreover, cyclic photocatalytic experiments demonstrated the high stability of g-C3N4-CdS-NiS2 composite. The improvement in the photocatalytic performance for H2 production can be mainly attributed to the formation of heterojunction between CdS, NiS2 and g-C3N4 nanotubes, which is beneficial to the separation of photogenerated electron-hole pairs.

    Synthesis of carbides supported on ordered mesoporous carbon by molten salt method
    Minshan MENG, Jiahua ZHAO, Pengfei ZHANG
    2020, 71(1):  409-416.  doi:10.11949/0438-1157.20191271
    Abstract ( 559 )   HTML ( 11)   PDF (1814KB) ( 258 )  
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    Ordered mesoporous carbon is a kind of nanostructured material with regular pore structure, high specific surface area and large pore volume. It is also a very good carrier material. Meanwhile, transition metal carbides have a series of properties that are similar to precious metals because of their structural characteristics. They can be used as catalysts with high activity in theory for heterogeneous catalytic processes to replace precious metals. However, transition metal carbides greatly affect the catalytic activity due to their low specific surface area and large particle size. Therefore, a variety of ordered mesoporous carbon-supported transition metal carbides were synthesized by molten salt method, and the samples were characterized by SEM, TEM, XRD and BET. The results show that the method can form carbon-supported metal carbides such as TiC and Mo2C with small particle size and high specific surface area, which has better prospects for catalytic application.

    Preparation of GNs/[Bmim][BF4] composites and their supercapacitive properties
    Ying WEI, Mingsong TAO, Yaofeng ZHU, Qingguo ZHANG
    2020, 71(1):  417-425.  doi:10.11949/0438-1157.20191236
    Abstract ( 523 )   HTML ( 4)   PDF (1349KB) ( 386 )  
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    A one-step electrochemical exfoliation method was appliled to electrolyze a graphite rod in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]), and the exfoliation product was thermal-treated to obtain graphene/ionic liquid composite (GNs/[Bmim][BF4]). Then, the composite was characterized by methods of infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Raman spectroscopy. The plenty porous structure which can facilitates the retention of the electrode structure and the transfer of charge during charge and discharge was found in the composite of GNs/[Bmim][BF4]. When the composite was used in supercapacitor electrode, the performence was found to be superior to graphite. At 0.2 A/g current density, the specific capacitance can reach 221.32 F/g, and when the power density was 456.32 W/kg, the energy density was up to 83.51 (W·h)/kg.