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Table of Content
10 October 2021, Volume 40 Issue 10
    Special column:Resource recycling and value-added utilization
    Research progress on comprehensive recovery and utilization of copper slag
    WANG Linsong, GAO Zhiyong, YANG Yue, HAN Haisheng, WANG Li, SUN Wei
    2021, 40(10):  5237-5250.  doi:10.16085/j.issn.1000-6613.2021-0657
    Abstract ( 478 )   HTML ( 27)   PDF (1216KB) ( 579 )  
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    Copper slag is a by-product of pyrometallurgical copper smelting. More than 90% of copper is produced by pyrometallurgical copper smelting. With the progress of science and technology and the needs of people's life, the output of copper in China is increasing year by year. Copper slag contains a lot of recoverable valuable metals, and it is also an excellent inorganic material. The comprehensive recovery of valuable metals in copper slag can reduce the pressure caused by insufficient resources, and the utilization of residual slag can not only reduce environmental pollution, but also produce products with economic value. This paper analyzed and discussed the principle, current situation, advantages and disadvantages of recovering valuable metals from copper slag by means of pyrodilution, wet leaching, beneficiation enrichment and combined process, and summarized the application of copper slag as silicate inorganic materials in building materials and functional materials. The future development direction of metal recovery and resource utilization of copper slag was prospected.

    Current status of control technology of Fe impurity in recycled aluminum alloy
    HE Xuefeng, LIU Bo, ZHANG Shengen
    2021, 40(10):  5251-5269.  doi:10.16085/j.issn.1000-6613.2021-0653
    Abstract ( 285 )   HTML ( 6)   PDF (9353KB) ( 160 )  
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    Using waste aluminum as raw material to produce recycled aluminum can reduce bauxite consumption and avoid high energy consumption and high emission in electrolytic aluminum production process. Due to the complex source and high pretreatment difficulty, a large amount of iron impurities are inevitably mixed in waste aluminum. Iron-containing impurities will form iron-rich intermetallic compounds of α-Fe, β-Fe, δ-Fe and π-Fe, which will significantly reduce the mechanical and corrosion resistance of recycled aluminum alloy, deteriorate castability, and lead to the degradation of recycled aluminum products. In this paper, the research status of iron-containing impurity removal technologies in aluminum alloys was reviewed. These technologies mainly included centrifugal method, electromagnetic method, filtration method, flux method, metamorphic element method, ultrasonic treatment, heat treatment and so on. The development trend of iron removal technologies in the future was prospected. In the future, the integrated calculation method should be introduced on the basis of crystal growth and solidification theory to explore the mass transfer, diffusion, enrichment, segregation and migration of iron in aluminum alloy, which had a strong guiding significance for the control of iron-rich phase. A new type of flux with high iron removal rate and green environmental protection was developed to improve the ability of flux to adsorb Fe impurities, the kinetic process of reaction with Fe impurities, and the uniformity and stability of reaction with aluminum melt.

    Research progress and challenges in recycling of typical alloys
    WANG Man, XI Xiaoli, WANG Yanan, TANG Kangyao
    2021, 40(10):  5270-5280.  doi:10.16085/j.issn.1000-6613.2021-0806
    Abstract ( 237 )   HTML ( 8)   PDF (1534KB) ( 451 )  
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    As one kind of critical basic materials, high-performance alloys play a vital role in high-end equipment manufacturing, new energy and other strategic emerging industries. With the development and growth of strategic emerging industries in China, demands for alloy materials with high performance will increase substantially. However, preparation of alloy materials needs to consume a large amount of metal mineral resources, which includes various scare metals. At the same time, the social accumulation of scrap alloys will increase year by year, resulting in ecological problems. Therefore, how to achieve coordinated development among resource, development and environment has become an international research hotspot. Circular economy has been considered to be an important way to achieve sustainable development. Cemented carbides, lightweight alloys and high temperature alloys have a wide range of important applications in national economy and defense construction. In this paper, three typical alloys including tungsten carbide cemented carbide, lightweight aluminum alloys and high temperature nickel-based alloys were selected, and their resource reserves, scrap characteristics and recycling technologies were systematically analyzed. Finally, the prospective of alloying recycling in the future was given.

    Review and perspective of vanadium extraction techniques from converter vanadium-bearing slag
    QIU Yuchao, SHI Junjie, YU Bin, XIAO Pan, ZHAO Fei, MA Wenyuan, LI Jianzhong, LIU Changsheng
    2021, 40(10):  5281-5292.  doi:10.16085/j.issn.1000-6613.2021-0807
    Abstract ( 282 )   HTML ( 5)   PDF (2092KB) ( 298 )  
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    It is an important aspect to ensure the sustainable development of China's vanadium industry by efficiently low-cost and green recover the vanadium from converter vanadium-bearing slag. Based on the composition and phase characteristics of the vanadium-bearing slag, the existing vanadium extracting techniques employed by different companies in the world were comprehensively summarized. The principle, advantages, as well as existing problems related to different vanadium extracting processes were clarified in reference to the traditional processes, i.e., sodium roasting - water leaching, calcification roasting-acid leaching, cleaner production technology of vanadium oxide by Panzhihua Iron and Steel Co. Ltd., and novel processes including microwave roasting, super-gravity selective separation, microbial metallurgy, etc. With the advancement of global carbon neutral targets, the development of future novel vanadium extracting technique should pay more attention to solve the existing environmental and resource problems including the large production of saline wastewater, the difficult harmless of the ammonium mirabilite and the difficult in re-using the sodium from the vanadium tailings. Meanwhile, the construction of the thermodynamic database and the dynamic models for the micro migration mechanisms of valuable metals should also be studied more deeply, and the advantages of microwave, super gravity, ultrasonic, etc. should be applied in traditional techniques. Furthermore, other valuable metals presented in vanadium-bearing slag should be efficiently recovered to realize pollution source abatement. Based on the new techniques and fundamental data, the further vanadium extracting process should be developed in the direction of green, low cost, short flow route and high efficiency.

    Pollution and utilization of chemical industry spent catalysts
    CAO Limei, QIU Zhaofu, ZHANG Wei, YANG Ji
    2021, 40(10):  5293-5301.  doi:10.16085/j.issn.1000-6613.2021-0800
    Abstract ( 288 )   HTML ( 7)   PDF (807KB) ( 467 )  
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    The chemical industry in the world replaces a large amount of spent catalysts every year. If the disposal method is improper, it will not only cause serious pollution to the ecological environment, but also waste resources. A preliminary investigation and analysis of the status quo of spent catalysts in the chemical industry were conducted in this paper. The sources, categories and characteristics of spent catalysts in the chemical industry were reviewed. Based on the characteristics that the content of valuable metals in spent catalysts was much higher than the corresponding components contained in mineral deposits, it was suggested to use them as secondary resources. The potential environmental risks of waste chemical catalysts were analyzed and environmental risk assessments were proposed. It was recommended to establish a database of environmental risk information for spent catalysts. The control methods and existing problems of spent catalyst reduction, resource utilization and harmlessness were discussed. It was proposed that the treatment and disposal of spent chemical catalysts should be considered from the perspective of clean production, not limited to pure end pollution control. It was recommended to develop new green technologies for spent catalyst reduction, recycling and harmless treatment to achieve the purpose of reducing pollution and comprehensive recycling of resources.

    Status and research progress on recovery of spent hydrogenation catalysts
    SHI Zhisheng, DING Yunji, ZHANG Shengen
    2021, 40(10):  5302-5312.  doi:10.16085/j.issn.1000-6613.2021-0654
    Abstract ( 295 )   HTML ( 7)   PDF (819KB) ( 298 )  
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    Spent hydrogenation catalysts are hazardous wastes and important secondary resources because they contain refractory organics and strategic metals such as Mo, W, Ni, Co and V. Resource utilization of spent catalysts has significant economic, social and environmental benefits. In this paper, the general situation of hydrogenation catalysts is introduced, and the recovery status of spent hydrogenation catalysts, including acid leaching, alkali leaching, roasting-leaching progress and pyrometallurgical progress is reviewed. Organic matter should be removed by solvent washing, mechanical method or roasting before recovery. The acid concentration of acid leaching is high, which is corrosive to equipment. The recovery rate of Ni and Co by alkali leaching is low, and the high-efficiency recovery of polymetallic can be realized by alkali leaching and acid leaching. However, hydrometallurgical progress has serious problems, such as the generation of wastewater and serious pollution. Roasting-leaching is the main recovery method at present, which has been industrially applied, but there are some problems such as long recovery process and a large amount of subsequent leaching wastewater. In order to solve the problems of water pollution, the method of enriching and recovering valuable metals by carbothermic reduction and using tailings for green building materials is put forward, and the prospect of metal recovery of waste catalyst is discussed.

    Research on disposal methods of spent vanadium-titanium-based catalysts
    HOU Xuejun, ZHANG Xiaoming, CHENG Wenbo, WANG Xin, WANG Chunxia, XU Shengming, HUANG Guoyong
    2021, 40(10):  5313-5324.  doi:10.16085/j.issn.1000-6613.2021-0568
    Abstract ( 226 )   HTML ( 5)   PDF (1174KB) ( 222 )  
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    At present, coal-fired power generation still accounts for a large proportion of the total power generation in China. Coal-fired power plants will produce a large amount of NOx which can cause harm to the human body and the environment. Therefore, it is essential to properly handle the NOx produced by coal-fired power plants. It is very important to control NOx emissions through using the selective catalytic reduction (SCR) technology. As the core of SCR system, a large number of vanadium-titanium-based SCR catalysts has been applied to remove NOx in coal-fired power plants. It has been an urgent problem to dispose the spent SCR catalysts. In order to motivate further research in the regeneration process of catalyst and the recovery of valuable metals, this paper systematically collated the literature in the corresponding background. The latest research on the catalyst regeneration process and the valuable metals recovery technology were introduced. The challenges related to the regeneration processes and the technologies of valuable metals recovery were analyzed. In addition, the guidelines on how to develop effective regeneration processes and recovery techniques for spent vanadium-titanium-based catalyst were proposed.

    Applications of thermodynamic research in recycling of lithium ion battery
    LIU Zixiao, ZHANG Jialiang, YANG Cheng, CHEN Yongqiang, WANG Chengyan
    2021, 40(10):  5325-5336.  doi:10.16085/j.issn.1000-6613.2021-0818
    Abstract ( 453 )   HTML ( 22)   PDF (2972KB) ( 554 )  
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    Recycling of spent lithium ion batteries has become a hot topic in the field of resource recovery recently, but the theoretical basis of related recovery system is still comparatively weak. In the aspect of thermodynamics, most researchers still take the classical theory of metallurgical physical and chemical as the guide, and carry out research with the help of E-pH diagrams, predominance diagrams and other methods. In this paper, the existing typical thermodynamic studies in this field were reviewed. The guidance of thermodynamic research on the current recovery process of spent lithium ion batteries, the inspiration for the selective extraction of lithium from spent ternary cathode materials and lithium iron phosphate cathode materials, and the development of new technologies for the regeneration of failed battery materials were described in detail. Meanwhile, based on the summary and review of the existing research on the thermodynamics of lithium ion battery recycling system, the key problems to be solved and the direction for future thermodynamic research on lithium ion battery recycling were pointed out.

    Research progress on cleaner production and engineering of calcium carbide preparation
    XU Wanyi, WANG Hongxia, CUI Xiaomi, ZHANG Zaoxiao
    2021, 40(10):  5337-5347.  doi:10.16085/j.issn.1000-6613.2020-2156
    Abstract ( 264 )   HTML ( 8)   PDF (748KB) ( 459 )  
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    China is the biggest calcium carbide production country in the world, and the calcium carbide production is an important part of chemical industry. Currently, the electric-thermal method is the most widely used industrial calcium carbide production method. But due to its high energy consumption, high pollution, high investment, low output, and many other disadvantages, the traditional calcium carbide industry is in urgent need of process upgrading. It is becoming a research hotspot to develop large-scale integrated calcium carbide industry chain with energy saving, consumption reduction, comprehensive and efficient utilization of raw materials and additional product. Oxygen-thermal method has the characteristics of low energy consumption, low material consumption, high efficiency and less pollution, which is a promising new method to replace electro-thermal method. In this paper, the new technology of calcium carbide from coal is reviewed, including the technology of oxygen-thermal coal to calcium carbide production, the coal to calcium carbide polygeneration system and the clean production of calcium carbide. The research progress of oxygen-thermal calcium carbide method is summarized. Then, the coal to calcium carbide and chemical/power system polygeneration process, as well as the technical routes of carbide slag comprehensive utilization and waste gas trap are discussed and analyzed. The further worthy research directions are also prospected. It is of great significance for the theoretical research, engineering practice and system operation of the clean and high-efficiency calcium carbide production.

    Biorefining of biocrude oil: recirculation of by-products and hydrothermal autocatalysis
    GAO Chuanrui, TIAN Chunyan, LI Zhihe, YI Weiming, YUAN Qiaoxia, FU Peng, ZHANG Yuchun, LI Zhiyu
    2021, 40(10):  5348-5359.  doi:10.16085/j.issn.1000-6613.2020-2183
    Abstract ( 206 )   HTML ( 1)   PDF (1064KB) ( 376 )  
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    Hydrothermal liquefaction (HTL) can simulate generation of crude oil under high temperature and high pressure. Bio-crude oil prepared by HTL can solve the problem of oil resource depletion in the future. However, the problem of disposal by-products during HTL restricts its sustainable development. One way to solve this problem is direct hydrothermal catalysis for bio-crude oil to reduce processing by-products and then integration of various technologies to in-situ convert by-products into resources. Based on this and according to biorefinery, a developing model integrating hydrothermal technologies to biorefinery of bio-crude oil was discussed in this paper. This model was based on analyzing the characteristics of hydrothermal by-products; then catalysts were prepared via hydrothermal synthesis of solid products, reusing of aqueous products, and separation or completely oxidization of gas products to produce organic acids; and finally, recirculation of hydrothermal by-products in this model was realized and biomass was autocatalyzed to produce biocrude oil again. This model conforms to the concept of green chemical industry and has important significance for accelerating the large-scale production of bio-crude oil and alleviating the energy crisis.

    Analysis of thermodynamics of vanadium extraction from clay vanadium ore by direct atmospheric pressure activation
    ZHANG Hao, YE Guohua, CHEN Ziyang, XIE Yu, ZUO Qi
    2021, 40(10):  5360-5369.  doi:10.16085/j.issn.1000-6613.2020-2103
    Abstract ( 167 )   HTML ( 0)   PDF (1329KB) ( 449 )  
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    At present, there are few experiments and basic researches on direct acid leaching of clay vanadium ore. In order to further promoted the research progress of this kind of problem, the method of experiment combined with thermodynamic calculation was adopted in this study. The results of the best leaching agent were obtained through experiments. The thermodynamic behavior and mechanism of vanadium leaching process were explained by thermodynamic calculation. The influence of total amount of different sulfur elements on the components of acid leaching solution was further analyzed. The solution chemical analysis was carried out for vanadium extraction process from acid leaching solution. The results showed that manganese dioxide has the ability to oxidize low valence vanadium to high valence vanadium, so as to improve the leaching rate of vanadium. The increase of temperature will have adverse effects on the improvement of leaching rate and the oxidation of manganese dioxide, but it will inhibit the leaching of impurities and have a positive impact on the separation of impurities. The amount of sulfuric acid not only affect the pH of the leaching process, but also affect the content of each component in the acid leaching solution. The solubility of iron impurities in the low sulfur system is lower than that in the high sulfur system, which is conducive to the separation of impurities in the process of vanadium extraction. By analyzing the change of solution components in the leaching process, the theoretical basis can be provided for the subsequent vanadium extraction process.

    Lithium storage performance of Fe-doped Xuan paper-based carbon fiber materials
    HU Sisi, SUN Lizhi, ZHANG Di, WANG Bo
    2021, 40(10):  5370-5377.  doi:10.16085/j.issn.1000-6613.2021-0146
    Abstract ( 162 )   HTML ( 3)   PDF (3505KB) ( 299 )  
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    In order to improve the high cost and environmental pollution of current lithium-ion battery electrode materials, a method of directly sintering and carbonizing Xuan paper made of plant fibers and modification of it as a lithium-ion battery anode electrode material was proposed. By changing the sintering temperature and time, the optimal carbonization mechanism of Xuan paper was explored, and then the Xuan paper-based carbon fiber materials were modified by doping Fe in a simple solution method and sintering method. The prepared materials were characterized and compared by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and X-ray energy spectroscopy (EDS). The results showed that Fe was successfully incorporated into the raw materials of Xuan paper. The material had strong flexibility and can be used directly as an electrode. The structure was uniform and stable, and the upper surface of the microstructure had many uniform micropores than before. The lithium storage performance of the prepared Xuan paper material as the anode electrode of the lithium ion battery was analyzed by the constant current charge and discharge method. The results showed that the first cycle specific capacity of the lithium-ion battery can reach 565.4mA·h/g at a current density of 500mA/g, and can still maintain a high capacity of 124.7mA·h/g when current density up to 2500mA/g. Besides, a stable and long lifespan of 1000 cycles at a current density of 1000mA/g can be also obtained.

    Mechanism and characteristics of nature inspired enzyme-fungi synergistic system for lignin pretreatment
    TANG Liang, LIAO Qiang, XIA Ao, HUANG Yun, ZHU Xianqing, ZHU Xun
    2021, 40(10):  5378-5387.  doi:10.16085/j.issn.1000-6613.2021-0642
    Abstract ( 171 )   HTML ( 3)   PDF (2646KB) ( 174 )  
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    The natural termite-fungi symbiosis system can effectively convert lignocellulosic biomass. Its essence is the destruction of physical structure, modification of functional groups and the reduction of non-productive adsorption of lignin to enzymes, thereby improving the efficiency of enzymatic saccharification, which can provide new opportunities for the utilization of biomass energy. Based on laccase (La) that degrades lignin phenolic units in the termite guts and Termitomyces sp. (Te) that degrades lignocellulose in the nests, this study proposed a new system for synergistically pretreating lignin. The pretreatment characteristics of La and typical lignin-degrading fungi Phanerochaete chrysosporium (PC) on the lignin model compound-alkali lignin was compared with Te. The results showed that the maximum activities of laccase and lignin peroxidase (LiP) produced by Te were increased by 43.3% and 58.5%, respectively, after the alkali lignin was pretreated by laccase. Meanwhile, the maximum activities of laccase and manganese peroxidase (MnP) produced by PC were increased by 35.9% and 31.6%, respectively. Laccase pretreatment enhanced the properties of Te and PC on functional groups modification and the physical structures destruction of alkali lignin. The results of fourier infrared transform spectroscopy (FTIR) showed that the absorption peaks of alkali lignin functional groups were significantly reduced after enzyme-fungi synergistic system pretreatment. The results of scanning electron microscopy (SEM) and mercury injection test showed that enzyme-fungi synergistic system severely damaged the surface structure of alkali lignin, and the average pore size of alkali lignin pretreated by La and Te synergistic (La+Te) system was significantly increased by 31.1% and 45.6% compared with single La and single Te, respectively. The maximum enzyme adsorption capacity of alkali lignin pretreated by La+Te system was 51.5% less than that of untreated alkali lignin sample. Due to the significant reduction of non-productive adsorption, the subsequent enzymatic hydrolysis conversion rate was 71.5% higher than that of untreated alkali lignin sample. This study demonstrated enzyme-fungi synergistic system was effective in altering the physical and chemical properties of alkali lignin, thereby promoting subsequent enzymatic saccharification of cellulose, which may provide guidance for biofuel production.

    Chemical processes and equipment
    Research and development of loop heat pipe with flat evaporator
    XIONG Kangning, WU Wei, WANG Shuangfeng
    2021, 40(10):  5388-5402.  doi:10.16085/j.issn.1000-6613.2020-2215
    Abstract ( 311 )   HTML ( 16)   PDF (4793KB) ( 396 )  
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    Loop heat pipe (LHP) is an efficient heat transfer device. Compared with other traditional heat pipes, the biggest advantage of LHP is its large heat transfer distance and anti-gravity operation. This study reviewed LHP, which is advantageous not only to the development of basic theory of LHP but also to the development and utilization of novel and high-efficiency LHP. In this review, the LHP are classified according to the shape of evaporator, and the progress of the experimental research and theoretical model research on the flat evaporator LHP in the past five years are introduced , including wick structure design, working fluid choice, evaporator optimization, evaporator model research and LHP system model research. In addition, the advantages and disadvantages of the six wick structures and their application status are analyzed, and the differences of several common working fluid and three conventional flat evaporator LHP system models are compared. Finally, the research status of flat evaporator LHP is summarized, and the scientific analysis and prospect of the experimental research and theoretical model research for the flat evaporator LHP are proposed.

    Development and prospect of solar-driven membrane distillation system
    LI Yihang, DAI Shaoling, YU Zhen, GU Ruonan, CHENG Shao’an
    2021, 40(10):  5403-5414.  doi:10.16085/j.issn.1000-6613.2020-2050
    Abstract ( 330 )   HTML ( 7)   PDF (7294KB) ( 181 )  
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    Seawater desalination is becoming the main technology to solve the increasing worldwide demand for freshwater, however, traditional seawater desalination faced with several disadvantages, such as high cost, high energy consumption, and low thermal efficiency. In recent years, solar-driven seawater desalination has received widespread attention due to its high efficiency and low cost. Among plentiful desalination systems, solar-driven membrane distillation (SDMD) is mostly studied due to its wide range of applications, high evaporation efficiency, low energy consumption, and low cost. A lot of works focused on SDMD structures and photothermal materials have been carried out to improve the performance, overcome the temperature polarization, and prevent membrane fouling. This article first classifies the existing SDMD systems according to the location of the photothermal conversion occurrence and then elaborates on the development status and technical bottlenecks of various SDMD. In addition, the limitations of current solar membrane distillation technologies and future challenges are also discussed for the further development and application of SDMD systems.

    Study on the separation of emulsified oil and fouling mechanism by deacetylated cellulose scetate membrane
    RAU Juiyeh, MAO Zhujian, LIN Xiaoyu, GUO Shaoying, HU Jiapeng
    2021, 40(10):  5415-5423.  doi:10.16085/j.issn.1000-6613.2020-1508
    Abstract ( 204 )   HTML ( 3)   PDF (2105KB) ( 171 )  
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    In this research, the cellulose acetate membrane (CA fiber membrane) was produced by electrostatic spinning, and the prepared CA membrane was modified by added TiO2 powder and deacetylated cellulose acetate (d-CA). After, the membrane filtration characteristics, permeation flux, removal efficiency of oil/water emulsion and membrane resistances were discussed. The results showed that the thermal stability and superhydrophilicity of the modification CA fiber membrane could be improved by TiO2 and D-CA, and the stable water and filtration flux were obtained. In operation conditions at 40kPa and 60 minutes, the TiO2@d-18.5%CA membranes were good membrane with water flux, filtration flux, removal efficiency of oil/water emulsion and backwash flux of 824.8L/(m2·h), (311.3±12.5)L/(m2·h), 93.6%±1.1% and 451.5L/(m2·h), respectively. The addition of TiO2 might lead to an increase in the irreversible resistance ratio of oil on the membrane surface. However, the d-CA modified could reduce the fiber membrane resistance and increase the proportion of reversible resistance, and improve the potential of CA fiber membrane in oil-water separation.

    Optimization of heat pump heat storage-heating system for suppressing fluctuation in power consumption
    LIU Xueling, FU Weijuan, NIU Jintao, WANG Yuanming
    2021, 40(10):  5424-5430.  doi:10.16085/j.issn.1000-6613.2020-2058
    Abstract ( 155 )   HTML ( 1)   PDF (779KB) ( 45 )  
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    Focusing on the problem of difference in the heating load between day and night for office building, which leads to sharp fluctuation in the power consumption of heat pump heating system within a day, thermal storage and heating system using heat pump that suppresses power consumption fluctuations is built, and optimization control strategy is proposed. Taking the stability of power consumption and lower electricity cost as the objective function, the parameters of heat storage and heating are optimized. Based on the weather parameters of Tianjin and one office building with 9000m2, the optimization in electricity consumption of the heat pump thermal storage and heating system is carried out. The results indicate that when thermal energy storage is added and the operation parameters is optimized, the valley power consumption is increased and the peak power load is reduced, which achieves the stable electricity consumption during one day. On typical days of heating, the power consumption during peak hours and hourly power consumption on typical day reduces 50.29% and 28.10%, respectively, and the hourly power consumption is stable at 53.54kW throughout the day. Compared with the conventional heat pump heating system without heat storage, the fluctuation of power consumption is greatly cut down and the total operating cost is reduced during the whole heating period.

    Analysis of performance of CO2 transcritical heat pump system with mechanical subcooling and ejector
    DONG Liwei, LI Minxia, YAO Liang, MA Yitai, ZHAN Haomiao
    2021, 40(10):  5431-5440.  doi:10.16085/j.issn.1000-6613.2020-2077
    Abstract ( 233 )   HTML ( 1)   PDF (2383KB) ( 107 )  
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    The use of ejector can reduce energy loss and improve the performance of cycle in heat pump. The ejector was integrated with the existing cycle,CO2 transcritical heat pump system with mechanical subcooling that major cycle with ejector and auxiliary cycle with ejector were proposed respectively. A thermodynamic model was developed to analyze the performance of system when using three different terminals, traditional designed radiator (TDR), floor-coil radiator (FCR) and small temperature difference fan-coil unit (STD-FCU). The new systems were compared with CO2 basic system (BASE) and CO2 mechanical subcooling heat pump system (MSHPS). Four typical climate cities were selected in China and heating seasonal performance factor (HSPF) were discussed during the heating season. The results indicated that a maximum coefficient of performance (COP) exists at optimum major discharge pressure, auxiliary discharge pressure and subcooler outlet temperature in mechanical subcooling system. The system with STD-FCU as the terminal has the highest COP. Compared with the COP of BASE system under rated condition, MSHPS (AWE) and MSHPS (MWE) can increase by up to 21.18% and 26.66% respectively. And compared with the COP of MSHPS, the new system can increase by about 2.62% and 9.53% respectively. MSHPS (MWE) has better performance improvement effect. MSHPS (MWE) can still operate under severely cold conditions. The system with ejector has higher HSPF in different temperature regions. The HSPF improvement effect of the cold regions represented by Harbin is most obvious. The system with TDR as the terminal is more suitable for the cold region of high latitude, and the system with STD-FCU as the terminal is more suitable for the area of low latitude. In addition, refrigerants used in auxiliary cycle affect the overall performance of the system. CO2 achieves the best effect in MSHPS (AWE) and R717 achieves the best effect in MSHPS (MWE).The system can reach higher COP when R32/R1234yf is employed in auxiliary cycle but can’t achieve the best effect.

    Analysis of droplet condensation process on solid cold surface
    ZHANG Zhe, ZHAO Enhui, YAN Lei, YANG Wenzhe, YUAN Hui, ZHANG Qiumei, TIAN Jinjin
    2021, 40(10):  5441-5450.  doi:10.16085/j.issn.1000-6613.2020-2118
    Abstract ( 210 )   HTML ( 1)   PDF (2460KB) ( 334 )  
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    Droplet condensation heat transfer mode in industry such as aerospace engineering, steam power engineering, chemical engineering has wide application. The individual droplet condensation process has been largely studied. The characteristics of droplet condensation group were studied in this paper. The condensation process of droplet on the cold surface of tetrafluoroethylene plate was observed by visual experimental equipment, and the change rule of droplet condensation process on the cold surface was explored under different conditions of subcooling degree and RH (relative humidity). The experimental results show that RH has the greatest influence on droplet condensation rate compared with subcooling degree. The number of droplets in the first generation was normally distributed with the setting time. The peak time of droplets in different subcooling degrees was 180—480s, and they were all concentrated in the range of 1.0×1012—1.6×1012. Under high RH, the droplet consolidation time is shorter and the second generation droplet condensation process is faster. During the formation of the second generation of droplets, the peak value of the number of droplets with high subcooling degree under different RH was higher than that with low subcooling degree. The subcooling degree of 24K at 80%RH was nearly 2 times that of 22K. The peak values of the area rate were all concentrated in the range of 75%—82%, and the area rate fluctuated between 65%—85% after stabilization. In engineering practice, it is of guiding significance to select environmental conditions under specific requirements of droplet state and to predict and judge droplet characteristics under corresponding environmental conditions. Improving the heat exchange performance of condensing and heat exchange equipment has positive significance for energy saving, raw materials and environmental protection.

    Deformation and Coulomb splitting mode of droplets under electric field
    WANG Junfeng, FAN Zhiheng, WANG Dongbao, LU Shuaiquan
    2021, 40(10):  5451-5458.  doi:10.16085/j.issn.1000-6613.2020-2150
    Abstract ( 231 )   HTML ( 2)   PDF (2052KB) ( 263 )  
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    A visual study of the microscopic morphological characteristics of methanol droplets under the action of an electric field was carried out based on high-speed tomography technology. The time-resolved deformation and the Coulomb splitting evolution behavior of charged droplets at different growth stages in a two-phase flow system were accurately captured. The details of the deformation and splitting process as well as behavior evolution of the charged droplets under different working conditions were achieved. Considering the coupled effect of the Coulomb force as well as dielectrophoretic force and the surrounding flow regimes on the droplet, the formation mechanism of the Coulomb split of the droplet at different growth stages in the presence of an electric field was revealed. The results showed that the electric field strength and the droplet size were the main factors that determine droplet deformation and the Coulomb splitting mode. The deformation and Coulomb splitting mode of charged droplets could be divided into pushed deformation, top breakup, top-sided breakup, and umbrella-shaped breakup. Combining the dimensionless parameters to quantitatively analyze the deformation and breakup characteristics of the droplet, the degree of droplet deformation and top breakup became more severe. The critical umbrella-shaped breakup length of the droplet decreased with the increase of the electric field intensity and the decrease of the droplet size.

    Performance analysis of heat pump water heater with different wrap-around condenser coil structure on the charging and discharging
    LIU Heng, TAN Jianming, LI Shuhong, DU Minghao, YE Qiang
    2021, 40(10):  5459-5467.  doi:10.16085/j.issn.1000-6613.2020-2206
    Abstract ( 190 )   HTML ( 3)   PDF (3452KB) ( 145 )  
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    The domestic air source heat pump water heater (HPWH) can efficiently produce hot water, and the optimization of the design of the wrap-around condenser coil structure can further improve the system performance. In this paper, the structure of the wrap-around variable-pitch condenser coil was proposed. The coupling model was formed by combining a MATLAB heat pump model with a CFD model of the water tank. The accuracy of the model was verified by experiments after it was simultaneously formed. The influence of wrap-around variable/constant-pitch condenser coil structure on the performance of heat pump water heater during charging and discharging was simulated and studied. The results showed that the average heat transfer coefficient and the COP of the wrap-around variable-pitch condenser coil structure on charging increased by 21.91% and 10.75%, respectively, compared with the wrap-around constant-pitch condenser coil structure. The hot water temperature distribution was more uniform. The average heat transfer coefficient and the COP of the wrap-around variable-pitch condenser coil structure on discharging were slightly higher than that of the wrap-around constant-pitch condenser coil structure The hot water extraction efficiency and heat discharging efficiency were increased by 7.69% and 8.53%, respectively. The temperature quality of the hot water discharged from the water tank was improved. This paper provides the direction and guidance for the optimization design of the wrap-around condenser coil structure.

    Three-phase fluid dynamics simulation of ionic liquid system in mixer-settler
    TANG Qi, BAO Di, SHAO Shaoxiong, XU Ping, LIU Lianwei, ZHENG Weiming
    2021, 40(10):  5468-5479.  doi:10.16085/j.issn.1000-6613.2020-2216
    Abstract ( 199 )   HTML ( 1)   PDF (7711KB) ( 320 )  
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    As a new kind of green solvents, ionic liquids (ILs) have been widely studied in recent years and have potential application prospects in the spent fuel reprocessing technology. However, a lack of study on flow characteristics of ILs in the extraction equipment limits the practical applications of ILs extraction system. Mixer-settler widely used in extraction was taken as the research object in this paper. The deionized water and the 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C4mim][NTf2]) were adopted as the aqueous phase and the organic phase, respectively. The computational fluid dynamics (CFD) simulation was carried out to study the organic phase distribution, pressure field and turbulence degree, etc. at different agitation speeds, flow ratios and temperatures. Moreover, the influence of air on the flow behavior was considered. The simulation result accorded with the experiment data and the maximum error was less than 6.3%. The results showed that the mixing performance can be promoted significantly by increasing the agitation speed. The air flow rate at the outlet was increased significantly with increasing agitation speed when it exceeded 500r/min, which may affected the performance of clarifying chamber. Besides, the mixing performance of organic phase and aqueous phase can be promoted with increasing flow ratio and temperature at the agitation speed of 350r/min. The moment of agitator was effectively reduced by heating up. The organic phase velocity and the moment of agitator were not significantly affected by heating when the temperature exceeds 303K. Therefore, the actual process conditions were recommended to combine with heating and the adjustment of agitation speed for achieving better mixing performance while reducing the requirements of the clarifying chamber.A numerical simulation method for the three-phase system of ILs is set up in the study. Moreover, some reasonable suggestions are provided for optimizing the operating conditions of the mixer-settler, and a reference for further study of ILs extraction system is provided.

    Change characteristics of pressure drop and collection efficiency of the filter separators in the gas transmission station
    JING Peiyu, ZHENG Sijia, ZHANG Shuai, TANG Chao, DUAN Linlin, FU Bin
    2021, 40(10):  5480-5490.  doi:10.16085/j.issn.1000-6613.2020-2217
    Abstract ( 192 )   HTML ( 2)   PDF (4808KB) ( 109 )  
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    The typical horizontal filter separator in the gas station was taken as the subject to evaluate the collection efficiency and working status of the filter separators through their operational pressure-drops under different operating conditions and guide their field operation and replacement of their filter elements. The dust on-line detection technique and CFD simulation were adopted to analyze the static and dynamic characteristics of pressure drop and collection efficiency of filter separator under different running time and pressure. The major results were verified using actual values. The results indicate that the lower of initial pressure-drop of the filter separator , the lower of operating pressure at the same flow rate. With the increase of its operational time, a strong trend of the monitored pressure-drop values is negatively deviating their best-fitted curves, and its collection efficiencies also present a decreasing trend, especially at its lower operational pressure, due to the gas with higher flow velocity carrying more coalesced particles to the downstream and leading to the increase of downstream dust concentration at this operational condition. The errors of collection efficiencies obtained by the on-line particle monitoring technique and the CFD method are lower than 20%. The actual dust collection verified that both methods are of higher accuracy, reliability and suitable in the prediction on the evolution of the pressure drop and the collection efficiency.

    Nitration of n-hexane with NO2 and theoretical calculation
    LI Xingyan, WANG Mo, DAI Xuan, PENG Xinhua, TANG Shuangling
    2021, 40(10):  5491-5498.  doi:10.16085/j.issn.1000-6613.2020-2225
    Abstract ( 238 )   HTML ( 7)   PDF (834KB) ( 174 )  
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    Effects of reaction conditions on the nitration of n-hexane with NO2 were systematically studied, including reaction temperature, mole ratio of n-hexane to NO2 and reaction time. The results showed that the conversion of n-hexane could reach 85.9% under the following reaction conditions: reaction temperature 120℃, mole ratio of n-hexane to NO2 1∶2 and reaction time 4h. Density functional theory (DFT) was used to study the reaction mechanism, the activation energies (Ea) of three possible reaction mechanisms were calculated at the B3LYP/6-311++G(3df,2pd)//B3LYP/6-31G* level. The calculated results are consistent with the experimental ones and further indicated that the crucial step of the process is the O atoms’ attacking of the H atoms, and 2-nitrohexane and 3-nitrohexane are the main products. The data of molecular geometry, atomic natural charge and IR spectra showed that the breaking of C—H bond and the formation of N—H are cooperative. Obvious changes of molecular geometry and atomic natural charge happened to the atoms of C(5), H(7), O(22), O(23) and N(21), which all participated in the nitration process.

    Energy processes and technology
    Research status-in-situ and key challenges in pipeline transportation of hydrogen-natural gas mixtures
    SHANG Juan, LU Yanghui, ZHENG Jinyang, SUN Chen, HUA Zhengli, YU Wentao, ZHANG Yiwei
    2021, 40(10):  5499-5505.  doi:10.16085/j.issn.1000-6613.2020-2140
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    The fluctuation of wind and solar power is one of the important constraints on their development. It is generally believed that hydrogen production using renewable energy and applying the in-service natural gas pipelines to transport hydrogen-natural gas mixtures is one of the effective ways to absorb large-scale wind and solar electricity. In this review, the demonstration projects of hydrogen-mixed natural gas pipeline transportation were introduced. The technical research and development status of hydrogen-natural gas mixture pipeline transportation were expounded from such 4 aspects as hydrogen-compatibility of pipeline materials, hydrogen-suitability of equipment, operation and safety, and construction of standard system, and the problems and challenges faced by the development of hydrogen-mixed natural gas pipeline transportation at present were concluded. Considering the current situation of hydrogen-natural gas mixture pipeline transportation in China, it is recommended to deploy hydrogen-natural gas mixture supply network as a whole, promote the construction of hydrogen-blended natural gas infrastructure in an orderly manner according to local conditions, and strengthen the research on hydrogen-compatibility of pipe materials, hydrogen-suitability of equipment and components, and operation safety security techniques. Furthermore, it is advisable to carry out application demonstration projects, and establish the standard system as soon as possible, so as to promote the development of the hydrogen energy industry effectively.

    Heat-release behaviors during CH4 hydrate formation in porous sediments by differential scanning calorimeter
    ZHU Yujie, XIE Yan, ZHONG Jinrong, SUN Changyu, CHEN Guangjin, WANG Xiaohui
    2021, 40(10):  5506-5513.  doi:10.16085/j.issn.1000-6613.2020-2134
    Abstract ( 177 )   HTML ( 0)   PDF (2024KB) ( 110 )  
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    Comprehending the heat-release behaviors of natural gas hydrate during their formation in porous sediments is of great significance to the development of natural gas hydrate resources and the understanding of hydrate accumulation. In this study, the influence of quartz sand particle size, initial water content, temperature and salt conditions on the heat release behaviors during CH4 hydrate formation in porous sediments was investigated by using a high-pressure micro differential scanning calorimeter. The experimental results show that, as the particle size of the quartz sand decreases, the heat release rate for CH4 hydrate formation increases. The exothermic peak for CH4 hydrate formation increases obviously with the initial water content decreased. However, there is not a significant correlation between the final cumulative heat and initial water content in the experimental time. When the temperature is 263.15K, there is no obvious exothermic peak during the CH4 hydrate formation. The exothermic law during CH4 hydrate formation in 3.35% NaCl solution is consistent with that in deionized water system, but their overall heat release rate and cumulative heat are lower. The experimental results by micro calorimeter show good regularities, which also has certain reference value for the further development of the calorimeter in hydrate formation kinetics.

    Simulation and application of fixed-bed residuum hydrotreating unit process model based on RHDS-SIM
    FAN Ming, ZHAO Yuansheng, WANG Yuan, HE Shengbao
    2021, 40(10):  5514-5522.  doi:10.16085/j.issn.1000-6613.2020-2152
    Abstract ( 226 )   HTML ( 2)   PDF (814KB) ( 237 )  
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    The 2.4×106t/a capacity fixed-bed residuum hydrotreating plant process flow model for specialized process analysis and optimization was established by utilizing the Petro-SIM software and RHDS-SIM suite and was contributed to debottlenecking and making an effort to quality and margin incrementation. The accuracy and reliability of the model were validated, as well as the impacts on hydroprocessing by alternative hydrogen partial pressure and reactor inlet temperature were studied. As the hydrogen partial pressure changed from 12.76MPa to 13.34MPa, the catalysts life remaining of R1, R2 and R3 increased 6 days, 36 days and 33 days, respectively. The total desulfurization, demetalization and concarbon removal rate were enhanced by augment of R1 inlet temperature, while the chemical hydrogen consumption increased from 141.3m3/m3 to 144.7m3/m3. Raising the inlet temperature of R3 from 384℃ to 390℃, sulfur content of the hydro-treated residual reduced from 5514μg/g to 4880μg/g. The effect of decreasing MP steam consumption of the stripper on utility cost was also simulated. The results suggested that, when the flow rate of MP steam was lowered by 0.4t/h, a margin of about 1372000CNY/a could be obtained. Sidedraw flowrate of diesel should be controlled under 23t/h in order to meet the product specifications and downstream unit demands when increasing the diesel yields.

    Industrial catalysis
    Progress of electrocatalytic hydrogen evolution reaction catalysts
    WANG Chunxia, SONG Zhaoyi, NI Jiping, PAN Zongwei, HUANG Guoyong
    2021, 40(10):  5523-5534.  doi:10.16085/j.issn.1000-6613.2021-0763
    Abstract ( 640 )   HTML ( 47)   PDF (5839KB) ( 672 )  
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    Hydrogen energy is currently recognized as one of the renewable clean energy sources in the world, and it is the main substitute for fossil fuels in the future energy supply. As a green and sustainable hydrogen production method, electrocatalytic hydrogen evolution reaction has become the subject of extensive research in recent years. The development of high-performance, low-cost and high-activity hydrogen evolution catalysts is currently the main challenge. This article summarized the progress of high-performance catalysts used in the HER reaction in recent years that focused on the basic principle of the HER reaction, parameters that determined the HER performance, various kinds of transition metals and compounds, non-metal catalysts, single-atom catalysts and other electrocatalytic hydrogen evolution catalysts. The relationship between the catalytic activity and the different morphology, unique structure, chemical composition and synthesis method of the catalyst was also disscussed. Moreover, the synthesis strategy, the intrinsic activity of increasing active sites and the amount of active sites that influenced the catalytic activity were also reviewed.

    Recent advance in directing synthesis of aromatic hydrocarbon from syngas via oxygenated compound intermediates
    SHANG Yunshan, WANG Qianjin, YANG Jiayi, YUAN Delin, ZHANG Fan, LIU Hua, XING Aihua, JI Shengfu
    2021, 40(10):  5535-5546.  doi:10.16085/j.issn.1000-6613.2020-2069
    Abstract ( 286 )   HTML ( 15)   PDF (1891KB) ( 341 )  
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    Compared with the syngas to aromatics through methanol route, the one-step syngas to aromatics (namely STA) is a very promising non-petroleum base route, because of its advantages of low cost and short process. In this paper, the research progresses in the development of bi-functional catalyst for the one-step synthesis of aromatics were reviewed. Firstly, the process of one-step conversion of syngas to aromatic was introduced, with the focus on the preparing methods of various catalysts used. The impacts of the physical and chemical properties of metal oxide and zeolite on the catalytic behavior were summarized, including the composition of metal oxides, ratio of two metals, crystal morphology, crystal size, ratio of metal oxides to zeolite, and acidity and diffusivity of zeolite. Furthermore, it introduced the forms and formation mechanisms of different intermediates on bifunctional catalyst. Finally, this paper reviewed current issues and challenges on one-step conversion of syngas to aromatic, and pointed out that the development of high-performance catalyst is the main research direction in the future.

    Preparation of ɛ-MnO2 with different morphologies and their catalytic combustion of toluene
    YU Weixiong, CHENG Gao, CUI Xiao’e, ZENG Xiaohong, LAN Bang, LI Yongfeng, ZHANG Canyang, SUN Ming, YU Lin
    2021, 40(10):  5547-5553.  doi:10.16085/j.issn.1000-6613.2020-2037
    Abstract ( 212 )   HTML ( 11)   PDF (1266KB) ( 161 )  
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    ?-MnO2 with different morphologies, including sphere, ellipsoid and cube were prepared by three methods and their catalytic activities were investigated by catalytic combustion of toluene. The physicochemical properties of the ?-MnO2 catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption-desorption, X-ray photoelectron spectrum (XPS), and H2-programmed temperature reduction (H2-TPR). The results showed that the catalytic activity of ?-MnO2 depended strongly on the morphology, following the sequence of sphere > cube > ellipsoid. The superior catalytic activity of sphere-like ?-MnO2 was due to its larger surface area, higher content of Mn3+ and better reducibility. Moreover, the sphere-like ?-MnO2 still kept good catalytic activity after a 60h long-term test.

    Materials science and technology
    Research progress on preparation and application of microcapsule phase change materials
    GONG Xue, WANG Chengyao, ZHU Qunzhi
    2021, 40(10):  5554-5576.  doi:10.16085/j.issn.1000-6613.2020-2165
    Abstract ( 378 )   HTML ( 12)   PDF (8849KB) ( 531 )  
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    Microcapsule phase change material (MCPCM) can achieve the encapsulation of the phase change materials and avoid leakage and agglomeration. It has broadened the application fields of phase change materials and has a great prospect. The core and shell materials of MCPCM were firstly introduced. Then, the principles of spray drying, sol gel, complex coacervation, interfacial polymerization, in-situ polymerization, suspension polymerization and microemulsion polymerization methods were elaborated. The microscopic morphology characteristics of MCPCM were presented. Furthermore, the influences of particle size distribution, encapsulation ratio and core-shell ratio on the thermal stability and heat storage capacity of MCPCM were analyzed. Meanwhile, the application of MCPCM in the fields of building energy conservation, heat storage and temperature regulation textile, military aviation, energy utilization and other fields were summarized. Finally, the research direction of microcapsule phase change materials had been prospected.

    Progress in the membranes of polymers of intrinsic micro-porosity PIM-1 for gas separation
    GUO Haiyan, PENG Donglai, FENG Xiaoquan, JIN Yehao, TIAN Zhihong, WANG Jing, ZHANG Yatao
    2021, 40(10):  5577-5589.  doi:10.16085/j.issn.1000-6613.2020-2061
    Abstract ( 488 )   HTML ( 17)   PDF (3081KB) ( 494 )  
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    PIM-1(polymers of intrinsic micro-porosity) constructed by rigid and contorted component monomers has the characteristics of high surface area, good thermal stability and solvent treatability and is one of the most studied polymers of intrinsic micro-porosity. When compared with traditional polymer membrane, PIM-1 has extremely high gas permeability for molecules, making PIM-1 membrane a promising research value and application prospect in the field of gas separation. Therefore, it is necessary to summarize the current research progress and discuss the key problems restricting the development of PIM-1 membrane and their solutions. In this review, the performance index of gas separation membrane and the gas transfer model in the membrane were summarized firstly, and the main research progress of PIM-1 membrane of gas separation in the past two decades was summarized emphatically, including the progress in pure PIM-1 membrane and modified PIM-1 membranes and PIM-1 mixed matrix membranes. Simultaneously, the influence of diverse modification techniques on PIM-1 and the structure-property relationship was analyzed. Finally, the future research focus of PIM-1 membrane and the problems that needed to be solved before realizing industrial application was intensively discussed, such as to study on improving the permselectivity of PIM-1 membranes and strengthening the membrane stability and thinness.

    Research progress in molybdenum disulfide nanosheet-based NF/RO membranes for water treatment
    ZHAO Dongsheng
    2021, 40(10):  5590-5599.  doi:10.16085/j.issn.1000-6613.2020-2143
    Abstract ( 250 )   HTML ( 4)   PDF (3069KB) ( 319 )  
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    The inherent defects in the molybdenum disulfide (MoS2) nanosheets and the nano-confined channels between the nanosheets are beneficial to enhance the perm-selectivity of nanofiltration/reverse osmosis (NF/RO) membranes. In this paper, the sandwich structure of the MoS2 nanosheets, and their merits of easy functionalization, high adsorption capacity and redox removal ability, good smoothness and stability of interlayer nano-confined channels, and nice antifouling properties are introduced firstly. After that, the latest research progress of MoS2 nanosheets in nanoporous membranes, laminated membranes and mixed matrix membranes are reviewed. Finally, the critical issues in the future development of the MoS2 nanosheets based NF/RO membranes are summarized, mainly including the preparation of large-scale nanosheets and uniform sub-nanopores, the construction of ultra-thin and perfect MoS2 separation layer, the exploration of molecular and ion transport behaviors and potential separation mechanisms in the nano-confined channels, and the modification strategies to enhance their interfacial compatibility in polymer matrix, which are of great significance for the development of the next-generation high-performance NF/RO membranes.

    Application of electrospinning and electrospray technology in battery/cell field
    DENG Jianhui, YANG Xiaoqing, FANG Chenghui, CAO Dongqing, LI Liangjun, ZHANG Guoqing, GUO Jianwei
    2021, 40(10):  5600-5614.  doi:10.16085/j.issn.1000-6613.2020-2080
    Abstract ( 381 )   HTML ( 13)   PDF (8589KB) ( 340 )  
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    Among various methods for preparing nanomaterials, electrostatic spinning (electrospinning) and electrostatic spraying (electrospray) technologies have opened up low-cost, simple, and efficient routes for continuous nanofiber manufacturing in the past decades, which have attracted widespread attentions from numerous researchers. Therefore, this paper introduced the basic theory, the affecting parameters and the categories and characteristics of various electrospinning and electrospray technologies, including solution electrospinning, melt electrospinning, gas-assisted electrospinning, emulsion electrospinning, coaxial electrospinning, multi-jet electrospinning and needleless electrospinning. Furthermore, this work introduced the technical advantages of electrospinning and electrospray strategies, as well as their frontier applications in energy storage field, especially in lithium ion batteries, fuel cells, solar cells and supercapacitors. Finally, the challenges and development prospects of the electrospinning and electrospray technologies were forecasted.

    Research progress of surface protection coatings for concrete
    LIU Jing, MIAO Tongmeng, JIANG Ziqing, XU Yongjie, ZHONG Zilong, YU Peiyun
    2021, 40(10):  5615-5623.  doi:10.16085/j.issn.1000-6613.2020-2131
    Abstract ( 247 )   HTML ( 5)   PDF (4657KB) ( 268 )  
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    The concrete as a material of the porous engineering structures is easy to speed up the corrosion with outside water and harmful materials in temperature and external stress, and thus affecting the durability. Therefore, the high performance protective coatings of concrete have an important role in extending the service time. In this paper, the research status, existing problems and development direction of surface film-forming coating, silicone penetrating coating and pore closing coating on concrete surface protection were systematically introduced.

    Preparation of nanocellulose/Al2O3 sol/PE lithium-ion battery separation membrane and its film-forming mechanism
    SHI Peidong, HU Chunrui, ZHENG Miaomiao, ZHAO Juan, LIU Rui, JIA Yuanyuan
    2021, 40(10):  5624-5633.  doi:10.16085/j.issn.1000-6613.2020-1928
    Abstract ( 233 )   HTML ( 1)   PDF (7436KB) ( 204 )  
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    Currently, polyolefin films are commonly used as commercial battery’s separation membranes, but their poor thermal shrinkage and weak mechanical properties limit the application of lithium-ion batteries. Therefore, it is particularly important to develop the membranes with high thermal stability and excellent wettability in organic liquid electrolytes. The nanocellulose/Al2O3 colloid /PE separation membrane for lithium-ion battery was prepared by layer-by-layer self-assembly technology, and the optimal preparation conditions for the NC/A-PE membrane were determined as the solid content of Al2O3 sol 2%(mass fraction), the solid content of wheat bran nanocellulose suspension 0.2%(mass fraction), the infiltration time 5min, and the number of assembly layers 20. The thermal stability and the wettability of the electrolyte were improved with a 235.2% increase in the maximum Young’s modulus, which can effectively resist deformation during the membrane assembly. Scanning electron microscope (SEM), atomic force microscope (AFM) and field emission electron microscope (FEM) characterizations confirmed that aluminum oxide and nanocellulose were successfully assembled on the PE membrane, showing a stratified structure with distinct layers and uniform thickness. The battery separation membrane prepared by this method was green, safe, and non-toxic, and its thermal stability, mechanical properties and wettability to electrolyte have been significantly improved, showing a potential application prospect.

    Preparation and properties of coal pitch-based water-absorbing resin
    MA Xinru, GUO Tao, WANG Qun, LI Junmei, ZHANG Zhennan, CAO Qing
    2021, 40(10):  5634-5641.  doi:10.16085/j.issn.1000-6613.2020-2105
    Abstract ( 185 )   HTML ( 1)   PDF (2072KB) ( 164 )  
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    With coal pitch as a raw material, air as an oxidant, and alkaline aqueous solution as the reaction medium, the effects of liquid-solid ratio, solid-alkali ratio and reaction time on the oxidation rate of coal pitch were investigated. On this basis, a super absorbent resin was directly prepared by solution polymerization with the liquid product of coal oxidation (LP) and acrylic acid (AA) in water. In order to determine the optimal reaction conditions, the influence of the water absorbency performance of each factor through single factor and orthogonal design experiments were discussed. At the same time, the synthetic resin was characterized and the reaction mechanism was analyzed. Results showed that the resin synthesized by LP with acrylic acid, ammonium persulfate and N,N′-methylenebisacrylamide under the optimal reaction conditions of 75℃ and 30min had the maximum water absorption value. The infrared absorption spectrum confirmed that the synthesized resin contained the characteristic absorption peak of the aromatic ring of the aromatic component in LP. Among them, the water absorption rate in deionized water and 0.9% NaCl aqueous solution can reach the maximum of 613.3g/g and 42.2g/g, respectively. The mechanism of the synthetic resin was that the benzene polyacid in LP was connected with AA and N,N′-methylenebisacrylamide through ester group. This research explored a new alternative way for the efficient use of coal pitch.

    Three-dimensional hierarchical porous carbon derived from spent culture substrate of white fungus and its electrochemical application
    DENG Xiuchun, ZHUO Zuyou, BAI Xiaojie, SUN Jie, CHEN Yandan
    2021, 40(10):  5642-5651.  doi:10.16085/j.issn.1000-6613.2020-2113
    Abstract ( 179 )   HTML ( 0)   PDF (4854KB) ( 317 )  
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    Spent mushroom substrate has rich wood fiber matrix with loose and porous texture as well as mycelium protein, which brings an innate advantage to be used for the preparation of high-performance biomass-based porous carbon, and thus can also yield considerable ecological and economic benefits. Three-dimensional (3D) hierarchical porous carbon with high nitrogen-doping (7.78%) was prepared from spent culture substrate of white fungus by pretreatment with a mixture of NaOH/urea (mass ratio 7∶12) aqueous solution followed by high-temperature carbonization. The pore structure analysis results showed that the sample of BC-5-800 had a high specific surface area of 1568m2/g and total pore volume of 1.53cm3/g with mesoporosity up to 83%. With BC-5-800 as the working electrode, a high specific capacitance of 278F/g at 0.5A/g was recorded in a three-electrode test system and it could still maintained at 230F/g under 10A/g. When tested in two-electrode device, the energy density of BC-5-800 reached 5.83Wh/kg with power density as high as 6990W/kg, and the capacitance retention rate after 10000 charge-discharge cycles was 87%, showing excellent cyclic stability. This study paves a new way for the possible high-value reutilization of spent culture substrate of edible fungus.

    CO2 separation of Pebax-based mixed matrix membranes promoted by Cu(Qc)2
    NING Mengjia, DAI Yan, XI Yuan, ZHANG Xing, LIU Hongjing, HE Gaohong
    2021, 40(10):  5652-5659.  doi:10.16085/j.issn.1000-6613.2021-0963
    Abstract ( 230 )   HTML ( 6)   PDF (2560KB) ( 395 )  
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    In order to improve the CO2 separation performance of Pebax-1657, a metal-organic framework Cu(Qc)2 was prepared which could adsorb CO2 and be introduced into the Pebax-1657 matrix to prepare Pebax/Cu(Qc)2 mixed matrix membranes for CO2 gas separation. The films prepared by the solution casting method were characterized by scanning electron microscopy, thermogravimetric analysis, infrared spectroscopy and X-ray diffraction. Through the gas permeability test of the membrane, the effects of filler content, operating pressure and mixed gas on the gas permeability of the membrane were investigated. The results show that the random and effective stacking of the Cu(Qc)2 in the mixed matrix membranes create highly selective gas transport channels that dramatically enhance CO2/N2 selectivity. Both the CO2 permeability and CO2/N2 selectivity show a trend of first increasing and then decreasing with the increase of Cu(Qc)2 loading. When 3% Cu(Qc)2 filler is added, the CO2/N2 separation performance of the mixed matrix membrane is the best, and the CO2 permeability coefficient and CO2/N2 selectivity are 102 Barrer and 84, respectively. Compared with the pure Pebax-1657 membrane, it has increased by 45.7% and 40.0% respectively, successfully breaking the upper limit of Robeson separation, indicating that the mixed matrix membrane has potential in the application of CO2 separation.

    Fine chemicals
    Progress and improvement of inorganic polymer coagulant based on solid waste
    LIU Dingyi, WANG Bingyu, LI Shulin, XIE Huifang
    2021, 40(10):  5660-5669.  doi:10.16085/j.issn.1000-6613.2020-2065
    Abstract ( 231 )   HTML ( 6)   PDF (514KB) ( 305 )  
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    Inorganic polymer composite coagulants have superior flocculation ability, but few studies are on the preparation of inorganic polymer composite coagulants based on solid waste recycling. This paper introduced the preparation technology, properties and characteristics of three inorganic polymer composite coagulants based on solid waste, briefly described their application in water treatment, the interaction mechanism and existing problems, and combined with the research progress of new inorganic polymer composite coagulants to analyze the development direction of inorganic polymer composite coagulants based on solid waste. According to the current results, it was necessary to establish a comprehensive solid waste resource from the chemical composition of solid waste raw materials and optimize the inorganic polymer composite coagulant preparation process from different sources. Secondly, it was concluded that the technical and economic analysis should be carried out on the material and energy consumption of the coagulant to promote its large-scale production and use. It was suggested that the solid waste of sludge should be recycled and the inorganic salt produced in the preparation process should be paid attention to avoid the adverse effect on water quality. The results showed that it was necessary to strengthen the study of coagulant functionalization and develop the solid waste inorganic polymer composite coagulant with a synergistic effect.

    Screening and application of hydroxylamines as inhibitors based on density functional theory
    TANG Yafang, HUANG Zhankai, ZHAO Jia, HE Yanzhen, ZHAO Fuli, ZHANG Chunli, LIU Hongguang, HAN Enshan
    2021, 40(10):  5670-5677.  doi:10.16085/j.issn.1000-6613.2020-2164
    Abstract ( 182 )   HTML ( 2)   PDF (1659KB) ( 170 )  
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    The relationship between the polymerization inhibition of hydroxylamines in styrene and their electronic properties was studied. The energy of their frontier orbitals were caculated at the density functional B3LYP level using the 6-31g(d) basis set, and the electronic properties related to polymerization inhibition were also calculated. Through a combination of theoretical analysis and experiments, it was found that hydroxylamines with good polymerization inhibition on styrene had the characteristics of high electron delocalization of HOMO, low bond gap, high molecular hardness, low electronegativity and electrophilicity. Among these factors, bond gap, molecular hardness, electronegativity and electrophilicity were more important than the electron delocalization of HOMO. It could be found that there was a linear relationship between the induction period and the molecular electrophilicity. In addition, the synergistic effect of hydroxylamine and DNBP (2-sec-butyl-4,6-dinitrophenol) could also be explained by density functional theory (DFT) calculation, which further proved that DFT calculation played an important role in the screening and application of polymerization inhibitors.

    Continuous-flow diazotization of methyl anthranilate in microreactor system
    WANG Ben, WANG Chao, YIN Jinhua
    2021, 40(10):  5678-5691.  doi:10.16085/j.issn.1000-6613.2020-2203
    Abstract ( 362 )   HTML ( 6)   PDF (6693KB) ( 295 )  
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    The diazonium salt of methyl anthranilate (MA) is an typical diazo compound, which has been widely used in the field of modern organic synthesis due to its high chemical selectivity and high efficiency in the synthesis of complex molecules. The inherent defects in the traditional semi-batch synthesis process and the potential explosiveness of MA diazonium salt limit its application on industrial scale. In this paper, a continuous flow process for the synthesis of MA diazonium salt was proposed in a high-throughput microchannel reactor with “heart-cell” structure. Based on the single factor experiment, Box-Behnken design (BBD) center combination principle was used to construct the response surface model to optimize the process. The effects of interaction between different reaction conditions on the reaction were studied and compared with the laboratory scale semi-batch synthesis process. The results showed that the continuous diazotization process in micro reactor had significant effect on reducing the interaction effect of factors, improving the process controllability and inhibiting the parallel side reactions. The yield of MA diazonium salt of 92% was achieved under the optimized reaction conditions of n(MA)∶n(sodium nitrite)∶n(hydrochloric acid)= 1∶1.15∶2.67, reaction temperature 34.62℃ and residence time 45.07s, which is 10% higher than the semi-batch synthesis process. The high sensitivity to temperature of the diazotization synthesis system in the traditional semi-batch process can be effectively solved by this new synthesis method, which avoided the security hidden danger caused by the difficulty of reaction temperature control and the risk of high potential thermal runaway.

    Epoxidation modification of waste aramid fiber powder and properties of curing products
    YU Pengda, ZHANG Xiaoxian, ZHANG Jinfeng, TAN Jihuai, WANG Fang, WANG Fang, FU Bo, ZHU Xinbao
    2021, 40(10):  5692-5698.  doi:10.16085/j.issn.1000-6613.2020-2224
    Abstract ( 174 )   HTML ( 1)   PDF (1169KB) ( 76 )  
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    Aiming at the high-value low-molecular-weight para-aramid (PPTA) produced from the waste material of para-aramid fiber production, an effective recycling method was discussed. Epoxy group modified PPTA(PPTAGE) was prepared with PPTA as the raw material and epichlorohydrin as the modifier using an adopting metalized/substitution reaction. The synthesis conditions of PPTAGE were optimized through single factor experiments. The results showed that the suitable synthesis conditions of PPTAGE were m(ECH)∶m(PPTA)=3∶1, the amount of NaH (the mass percentage of the materials input) was 0.4%, the reaction temperature was 80℃ and the reaction for 4.5h. The modified aramid fiber was used as the filler of the epoxy resin to obtain the cured products, and the effect of PPTAGE on the mechanical properties of the cured product was studied. The properties of the cured product indicated that the modified PPTA can improve the adhesion of PPTA to the epoxy resin matrix. When the addition amount was 1%, the mechanical properties of the cured product was the best. After adding PPTAGE, the cured product was thermal stalely. Compared with PPTA/E-51, its performance was improved. SEM test showed that the impact fracture surface of PPTAGE/E-51 was ductile fracture.

    Biochemical and pharmaceutical engineering
    Preparation of pharmaceutical nanocrystals using wet nanomilling—Hydrotalcite
    WANG Xiaokang, ZHANG Yang, FALOLA Akinola, HE Yunliang, WANG Xuezhong
    2021, 40(10):  5699-5707.  doi:10.16085/j.issn.1000-6613.2020-2179
    Abstract ( 248 )   HTML ( 2)   PDF (1650KB) ( 268 )  
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    Low dissolution rate and solubility severely affects their bioavailability and efficacy and is the main factor that led to failure in the development of candidate drug compounds. Recent studies revealed that when the particle size is reduced to around 100—200nm, its dissolution rate and solubility significantly increase. Hydrotalcite is an effective API (active pharmaceutical ingredient) for treating gastric diseases. Its nanoparticle suspension shows a better anti-acid effect and a faster onset of action. In this study, preparation of hydrotalcite nanocrystals using wet nano milling technology was investigated. In the process, sodium hexametaphosphate was selected as a dispersant, and the impacts of dispersant dosage, grinding speed, hydrotalcite content, as well as grinding time on the particle size distribution were examined. An operational envelope was unveiled to obtain a hydrotalcite nano-suspension with D10 (76.4nm), D50 (161nm), and D90 (352nm) with the grinding speed being 3000r/min, the grinding time 105 minutes, the main drug volume fraction 2%, and the dispersant being 1.5% of the solid content mass fraction. The acid-neutralizing capacity experimental result showed that the dissolution rate of the nano-hydrotalcite suspension in hydrochloric acid was 5 times faster than that of the micron-sized suspension.

    Resources and environmental engineering
    Advances in 1,4-dioxane remediation methods: a review
    TIAN Kun, YAO Dandan, ZHAO Yuantian, GUO Lili, DONG Yuanhua, LIU Yun
    2021, 40(10):  5708-5719.  doi:10.16085/j.issn.1000-6613.2020-2055
    Abstract ( 245 )   HTML ( 13)   PDF (1020KB) ( 424 )  
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    As an emerging environmental contaminant, 1,4-dioxane is widely distributed in surface water, groundwater and drinking water. It is difficult to remove 1,4-dioxane by conventional water treatment methods, so its treatment technologies have attracted widespread attentions. In recent years, attentions have been paid to the environmental behavior of 1,4-dioxane and its adverse effects on human health. The remediation technologies of 1,4-dioxane were reviewed in this paper. First, the nature and distribution characteristics of 1,4-dioxane were summarized, and the existing pollution investigation and control standards at home and abroad were compared. Then the development of technologies for controlling 1,4-dioxane pollution in recent years were introduced from three aspects including physical, chemical and biological methods. The removal mechanism, advantages and disadvantages of different methods, and feasibility were also introduced. The inhibitory effect and mechanism of bioremediation methods under the coexistence of chlorinated hydrocarbons and heavy metals were pointed out, and the existing methods to deal with mixed pollutants were introduced. Finally, the main directions of future research on 1,4-dioxane pollution treatments were prospected.

    A review on RO/NF membrane autopsy and membrane fouling diagnosis
    HAI Yuyan, HE Can, MA Rui, XIONG Rihua
    2021, 40(10):  5720-5729.  doi:10.16085/j.issn.1000-6613.2020-2474
    Abstract ( 289 )   HTML ( 7)   PDF (2565KB) ( 286 )  
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    Reverse osmosis (RO) and nanofiltration (NF) membrane fouling will inevitably occur during long-term operation, which causes the decline of membrane performance. Once the water quality cannot meet the requirement for specific application, the deteriorated membranes need to be replaced. Membrane autopsy is considered as the most intuitive and effective method for studying and identifying the membrane fouling. The results of membrane autopsy and membrane fouling diagnosis are analyzed to provide an effective basis for optimizing the operation of membrane system, maintaining the membrane elements in a regular routine and rejuvenating the membrane performance. However, the practice of membrane autopsy and the study of membrane fouling diagnosis are not systematic and comprehensive. According to the related research of RO/NF membrane autopsy and membrane fouling diagnosis, in this paper, the detailed procedure of membrane autopsy and various analytical methods of membrane fouling were introduced, and meanwhile the existing problems in the practical application were discussed. The diagnosis of fouling composition and spatial distribution, the comparison of membrane fouling in different application scenarios and membrane materials are mainly reviewed, which may provide an insight into studying the mechanisms and control methods of membrane fouling, and optimizing the operation of membrane system.

    Research progress of catalytic oxidation of typical VOCs in cooking oil fumes
    WEI Jinghui, FENG Yongchao, YU Qingjun, YI Honghong, TANG Xiaolong, ZHANG Yuanyuan, MENG Xianzheng, YUAN Yuting
    2021, 40(10):  5730-5746.  doi:10.16085/j.issn.1000-6613.2020-2039
    Abstract ( 226 )   HTML ( 4)   PDF (3790KB) ( 148 )  
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    In recent years, cooking oil fumes (COFs) have gradually become a major source of air pollution in cities. Volatile organic compounds (VOCs) in cooking oil fumes do great harm to both human body and environment, which need to be purified as much as possible. Catalytic combustion is an efficient and widely used technology for removing various organic compounds due to its high removal efficiency as well as environment friendliness. In this paper, the compositions of typical volatile organic compounds in COFs were firstly summarized and analyzed based recent researches. It was found that hydrocarbons, aldehydes and ketones are the major components in COFs, followed by esters, alcohols and a small amount of polycyclic aromatic hydrocarbons. Then, the research development on the catalytic oxidation of these typical VOCs in COFs was reviewed systemically. Particularly, the catalysts commonly used for the catalytic combustion, including precious metal catalysts, non-precious metal catalysts and catalysts with specific structure, were summarized. Finally, the feasibility of different types of catalysts for purifying the VOCs from COFs was analyzed based on the review above. Moreover, the application of catalytic combustion technology in the treatment of COFs was prospected.

    Progress in research on adsorption for abatement of indoor formaldehyde
    XIAO Kang, WANG Qiong
    2021, 40(10):  5747-5771.  doi:10.16085/j.issn.1000-6613.2020-2041
    Abstract ( 306 )   HTML ( 9)   PDF (4169KB) ( 369 )  
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    Adsorption has the advantage of maturity, easy to operate, highly developed system and small fixed investment, and thus this technology is widely used in purification of indoor airborne pollutants. In this paper, the progress in research on adsorption for abatement of indoor formaldehyde was shortly reviewed. Different types of adsorbents were described in respect of raw carbon based adsorbents, modified carbon based adsorbents, inorganic non-carbon based adsorbents and organic non-carbon based adsorbents. The adsorption capacities of different types of adsorbents were compared, the mechanism of interaction between formaldehyde and adsorbent surface was shortly described, and the major factors impacting adsorption efficiency were summarized in detail. Generally, modified carbon based adsorbents were superior to others while other types of adsorbents only showed slight differences and no obvious difference in comparison with commercial adsorbents. The structure and physicochemical properties of adsorbents were the principal factors that influenced the adsorption efficiency. Textural properties, surface acid-base properties, oxygen containing and heteroatom containing surface groups and surface secondary phases of adsorbents all significantly influenced the adsorption efficiency. The conditions such as formaldehyde concentration, adsorption temperature and humidity, and grain size of adsorbents were also the influencing factors on adsorption efficiency. All these factors were reviewed along with the influencing ways and rules.

    Review on soot formation during biomass pyrolysis
    JIANG Hao, ZHU Youjian, SHAO Jing’ai, CHENG Wei, WU Guihao, YANG Haiping, CHEN Hanping
    2021, 40(10):  5772-5785.  doi:10.16085/j.issn.1000-6613.2020-2208
    Abstract ( 248 )   HTML ( 11)   PDF (5308KB) ( 513 )  
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    Soot, a type of solid carbonaceous nanoparticles, is the main components in PM2.5, and it is also the important contributor to global warming due to its high radiation. The generation of soot will reduce the energy utilization efficiency due to lower carbon conversion rate during biomass thermal chemical conversion process, and it can also downgrade the quality and yield of syngas during biomass gasification. Pyrolysis is the initial process during biomass thermal chemical conversion process. The characteristics, formation mechanism and emission reduction methods of soot during biomass pyrolysis are significant for the control of soot during thermal chemical conversion process. This study summarizes the research progress of biomass pyrolysis soot from the respects of sampling, emission, characteristics analysis, formation mechanism and reduction methods, mainly discusses soot yield, chemical composition, micro-morphologies, internal structure and reactivity, and summarizes the effects of feedstock characteristics and pyrolysis conditions on soot yield and reactivity. Measures to achieve soot control are also summarized. The current studies were carried out through the analyze of final soot particles. The evolutionary transformation mechanism of soot precursors, soot oxidation and elimination during biomass pyrolysis are still unclear. In addition, the formation of soot during pyrolysis is affected by feedstock and pyrolysis conditions, but current studies mostly focused on the impact analysis of a single factor. The multi-factor optimization analysis on soot formation needs to be strengthened.

    Analysis of gasification characteristics of coal-petrochemical sludge at high temperature based on Aspen Plus
    CHEN Yangui, ZHANG Wenqi, WANG Yinfeng, LIAO Chuanhua, ZHU Yuezhao
    2021, 40(10):  5786-5793.  doi:10.16085/j.issn.1000-6613.2020-2042
    Abstract ( 219 )   HTML ( 1)   PDF (862KB) ( 268 )  
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    High temperature gasification-melting technology is one of the key technologies for harmless disposal and resource utilization of petrochemical sludge. The high temperature co-gasification of the petrochemical sludge-coal can melt the heavy metals and fly ash in the hazardous wastes and block the dioxins, and the syngas is taken as the product. The disposal process can realize zero emission and high value utilization of products. In this paper, an equilibrium model of coal-petrochemical sludge gasification process at high temperature was established based on Aspen Plus software, and the effects of oxygen consumption ratio and blend ratio on gasification characteristics as well as the synergetic effect of co-gasification were studied. The results show that CO and H2 in syngas increase first and then decrease with the increase of oxygen consumption ratio. With the increase of blend ratio (10%—50%), the optimal oxygen consumption ratio required for gasification decreases from 0.72 to 0.43, and the calorific value of syngas decreases from 11.1MJ /m3 to 10.4MJ /m3. The co-gasification of the sludge and coal can make more efficient use of the water in the sludge and has a certain efficiency of oxygen saving. The effective syngas (CO and H2) increases by 1.0%—7.1% compared with gasification alone. In addition, in order to meet the requirements of high temperature melting (1350℃), the blend ratio should not be higher than 30%.

    Performance of electroosmosis plus capping technology on preventing sediment contaminants from release
    LIU Liujun, HU Yue, LI Yan, YUE Rui, HU Jiangjun, ZHU Hua, WANG Xu, MAO Xuhui
    2021, 40(10):  5794-5803.  doi:10.16085/j.issn.1000-6613.2020-2082
    Abstract ( 146 )   HTML ( 0)   PDF (2674KB) ( 85 )  
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    In recent years, in-situ control techniques to remediate the endogenous pollution of sediments have received extensive attention. This study aims at unravelling the preventing effect of “electroosmosis plus capping” technology on the release of endogenous pollution from the sediments of contaminated water bodies using lab-scale experiments. The results of electroosmotic treatment showed that, with the increase in cell voltage, smaller amounts of ammonia nitrogen were released from the sediments after treatment into the overlying water, but larger amounts of total phosphorus released. The followed capping experiment results showed that the use of natural coarse river sand for capping exhibited had the best effect. With a higher cap thickness and smaller particle size, a better controlling effect on pollutant release could be obtained. If the sediments were treated by the optimal conditions, pretreated by 20V electroosmosis voltage, and capped by 3cm coarse river sand (with a particle size of 3—5mm), the highest controlling efficiency of pollutants could reach up to 66.9%. Results of this study demonstrate that “electroosmosis plus capping” technology has excellent pollution controlling effect and can be developed as an effective and in-situ method to block the release of endogenous pollution from the sediment. The potential ecological environmental effect needs further observation.

    Preparation and toluene adsorption performance of sludge based activated carbon with loading Cu and Mn
    LI Xiaofei, DU Gaiping, DUAN Weichao, SUN Hui, ZHAO Dongfeng, LI Shi
    2021, 40(10):  5804-5811.  doi:10.16085/j.issn.1000-6613.2021-0147
    Abstract ( 176 )   HTML ( 1)   PDF (4537KB) ( 159 )  
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    Sludge-based activated carbon loaded by copper and manganese (SAC-CuMn) of different ratios were prepared by using the residual activated sludge from petrochemical enterprise as carbon source, 4mol/L ZnCl2 solution as activator, CuC2O4 andMnC2O4 as modifiers via one-step calcined technique of solid phase blending. SAC-CuMn samples were applied to adsorb toluene gas and the adsorptive performances were studied to optimize the proportion of copper and manganese in SAC. When the mass ratio of CuC2O4 andMnC2O4 is 4∶1, the yield, BET surface area, total pore volume, and granularity of SAC-CuMn are 52%, 617.77m2/g, 0.61cm3/g, and 0.5mm, respectively, and the performances of toluene adsorption is optimal. At the same time, the SAC-CuMn samples were characterized by ICP, SEM, TEM, FTIR, XRD, EDS, MAPPING, and XPS and their differences were compared. Furthermore, the mechanisms of toluene adsorption by SAC-CuMn were discussed. The results indicated that Cu and Mn were uniformly loaded in the structure of SAC-CuMn samples by solid-phase blending method. In the process of toluene adsorption, physical adsorption and Cu(Ⅰ) complex adsorption played the roles simultaneously to improve the toluene adsorption ability of SAC efficiently. The adsorption amounts of toluene in the optimal SAC-CuMn sample can reach 459.09mg/g and the breakthrough time of dynamic adsorption exceeds 500min.

    Continuous capture of carbon dioxide by ZIF-8/ethylene glycol slurry
    PAN Yong, CHEN Chi, XU Baoming, CHEN Guangjin
    2021, 40(10):  5812-5817.  doi:10.16085/j.issn.1000-6613.2020-2099
    Abstract ( 198 )   HTML ( 5)   PDF (849KB) ( 307 )  
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    Effective CO2 capture is of great significance for reducing greenhouse gas emissions and controlling global warming. Zeolitic imidazolate framework-8 (ZIF-8) and ethylene glycol are mixed to form a flowable slurry via the combination of absorption and adsorption. A series of separation experiments were carried out in an atmospheric pressure transparent PMMA column (height 3.7m, inner diameter 50mm) and a high pressure stainless steel bubble column (height 3m, inner diameter 40mm) respectively. The rich slurry is desorpted in the desorption tank and then returned to the absorption tower to capture carbon dioxide. The whole separation process can be carried out continuously. The results show that the lower the absorption temperature and the mixed air flow rate, the higher the slurry regeneration temperature and the tower pressure, the greater the amount of carbon dioxide absorbed by the slurry. The optimum operating conditions were determined as follows: absorption temperature 0.5℃, gas flow rate 47mL/min, slurry regeneration temperature 333.13K, and operation under normal pressure. Under the optimum operating conditions, the separation factor was 395. After more than 100hours of operation, the structure of ZIF-8 did not change and the ZIF-8/glycol slurry could be reused, which demonstrated the potential industrial application value of ZIF-8/glycol slurry.

    Effect of mechanical force and microwave on the NH3-SCR denitration of rare earth tailings
    HOU Limin, YAN Xiao, QIAO Chaoyue, FU Shancong, WU Wenfei
    2021, 40(10):  5818-5828.  doi:10.16085/j.issn.1000-6613.2020-2175
    Abstract ( 171 )   HTML ( 1)   PDF (6676KB) ( 143 )  
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    Due to the complex association of minerals in rare earth tailings, some minerals cannot be fully exposed to show their activity. In the paper, rare earth tailings were activated by the combination of mechanical force and microwave. Orthogonal test was used to study the effects of operation parameters of mechanical force and microwave activation on the NH3-SCR denitration performance, with the aid of characterization methods of XRD, SEM-EDS, H2-TPR, NH3-TPD, and BET. The results showed that the significance of the parameters was in the order: ball to powder weight ratio > rotor speed > ball milling time = ball diameter ratio > calcination temperature = calcination time = calcination power. The optimum activation parameters were determined as powder weight ratio was 1∶1, rotor speed was 300r/min, ball milling time was 2h, ball diameter ratio was 1∶1∶1, calcination temperature was 250℃, calcination time was 20min, and calcination power was 1100W, under which the denitration activity of rare earth tailings increased by 40%. The specific surface area, mineral dispersion, amount of surface acid active site and redox performance of rare earth tailings can be improved. The uniform distribution of weak, medium to strong and strong acid active sites is beneficial to the denitration activity. The high degree of hematite exposure is conducive to the denitration of rare earth tailings.

    Deep treatment of sucralose wastewater with sulfur autotrophic/heterotrophic synergistic denitrification
    GENG Yawen, LIU Feng, FENG Zhen, CHEN Jun, ZHANG Xuezhi
    2021, 40(10):  5829-5836.  doi:10.16085/j.issn.1000-6613.2020-2181
    Abstract ( 222 )   HTML ( 4)   PDF (1319KB) ( 246 )  
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    In order to solve the problem of nitrogen pollution in industrial wastewater and the defects of denitrification technology of single electron donor, a sulfur autotrophic/heterotrophic synergistic denitrification system was constructed in an upflow high efficiency fluidized bed denitrification reactor with Na2S2O3 and glucose as substrates. The deep denitrification of the sucrose trichloride production wastewater was studied. Under (35±1)℃, influent C/N/S was adjusted to 1.3/1/1.9, the operation of reactor for 40~109d reached a high nitrogen removal level. NO3--N removal rates were above 93%, Maximum NO3--N removal load up to 3.52kg/(m3·d), And without pH buffer, effluent pH is always above 7.0. The community composition of sulfur autotrophic/heterotrophic synergistic denitrification sludge was mainly autotrophic denitrifying bacteria and concurrent denitrifying bacteria, the proportion of which was 45.69% and 25.38% respectively, and the heterotrophic denitrifying bacteria were relatively few. Among them, Thiobacillus were the most abundant autotrophic denitrifying bacteria, accounting for 39.02%.

    Experimental and mechanism studies on degradation of the organics in biochemical influent of coal chemical industry by ozone catalytic oxidation
    WANG Jikun, LI Yang, CHEN Guifeng, LIU Min, LI Wenbo, HE Yicong
    2021, 40(10):  5837-5844.  doi:10.16085/j.issn.1000-6613.2021-0872
    Abstract ( 183 )   HTML ( 5)   PDF (7794KB) ( 74 )  
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    The process conditions and mechanism of ozone catalytic oxidation degradation of organic compounds in the biochemical influent of coal chemical industry were studied. Taking a coal chemical biochemical influent in Xinjiang as model, the types and amounts of refractory organics in wastewater were determined. Then, ozone catalytic oxidation tests of the refractory organics were carried out and the removal rates of chemical oxygen demand (COD) under different technological conditions were investigated to determine the best reaction conditions. Finally, dissolved organic matter (DOM) was taken as the research object to analyze the degradation law of refractory organics in wastewater. The results showed that the organic compounds were mainly phenol and humic acid. The optimal process parameters were as follows: catalyst dosage was 1.2L/L, ozone concentration was 500mg/L, and ozone aeration rate was 2.5m3/h. The UV254 of each component decreased after the reaction, and the removal rates were in the order of hydrophobic neutral substance(HoN)>hydrophilic basic substance(HiB)>hydrophobic basic substance(HoB)>hydrophilic acid substance(HiA)>hydrophobic acid substance(HoA)>hydrophilic neutral substance(HiN). After the catalytic oxidation by ozone, the fluorescence intensities of fulvic acids, humic acids, protein and soluble biological metabolites all decreased.

    Chemical industry park
    “Six Integrations”of establishing and managing chemical parks in China
    YANG Ting
    2021, 40(10):  5845-5853.  doi:10.16085/j.issn.1000-6613.2021-1814
    Abstract ( 340 )   HTML ( 6)   PDF (1449KB) ( 404 )  
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    With the development of chemical parks in China stepping into the stage of maturity, the “Integration” has become a recognized model and development direction for the construction and management of chemical parks, which has also kept evolving. In this paper, the “Six Integrations”theoretical system for the construction and management of chemical parks nowadays was described, and the content and importance of “Six Integrations” formed in the construction and management of chemical parks were analyzed from aspects of their development concepts, principles, system construction and interrelationships. A coordinative cooperative and sharing system for raw material and product projects, public engineering logistics, safety and fire emergency response, environmental protection ecology, intelligent and smart data, and management service and technology innovation was established to upgrade the industry, improve the facilities and optimize the management of the chemical parks, so as to standardize the management mode and promote the high-quality development of the chemical parks.

    Perspective
    Status and thinking of development constraints of refining to chemical transformation in China
    WANG Deliang, ZHOU Zhimao, LIN Menglei, LI Chao
    2021, 40(10):  5854-5860.  doi:10.16085/j.issn.1000-6613.2021-0421
    Abstract ( 222 )   HTML ( 5)   PDF (646KB) ( 249 )  
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    China’s refining industry is suffering from overall overcapacity. Under the influences of national macro-control and resource constraints as well as economic development needs, the transition from refining to chemical transformation is now the general trend. This paper analyzed the relevant limiting factors in supply and demand sides of chemical production capacity, namely operating rate, chemical light oil yield, short-term and long-term demand for petrochemical products, and expansions in chemical production capacity, to provide suggestions for this transformation period. The result showed that in the near future the transformation was limited by the competitiveness of units, whereas in the long-term the maximum chemical demand became the critical constraint. Under existing operation rate and construction plans, the average chemical light oil yield from refineries would increase to 20.6% in 2025. With the construction of the new plants, the production capacity of chemical raw materials was expected to increase sharply, causing the allowed maximum capacity of chemical production to come sooner than 2025. Drawing from facts and historical mean consumption data from China, America, Japan and South Korea, it was suggested that the peak consumption of chemical light oil would reach 329 million tons. Meanwhile, the overall average yield of chemical light oil of Chinese petrochemical plants would reached 41% in the long term.

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