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Table of Content
25 August 2022, Volume 41 Issue 8
    Invited review
    PSE in China: retrospect and prospects
    YANG Youqi, CHEN Bingzhen
    2022, 41(8):  3991-4008.  doi:10.16085/j.issn.1000-6613.2022-0401
    Abstract ( 152 )   HTML ( 14)   PDF (5870KB) ( 159 )  
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    This was an overview on the developments of process systems engineering (PSE) in China, in memory of the establishment of the PSE Professional Committee under Systems Engineering Society of China for 30 years. The paper was divided into four parts. The first part of the introduction was a brief review of the origin of PSE as a discipline in China. The second part was the development contribution and problems of PSE in the past 30 years. The important achievements of PSE in the past 30 years (especially in the past 10 years) and its contribution to process industry were briefly reviewed and summarized, and some existing problems including the position of PSE in China were pointed out. The next half part of this paper was the prospect of PSE’s future developments. In the third part of challenges and opportunities on future developments for PSE, the development situation for PSE were introduced from the global perspective and the perspective of China’s future development of the problems. It was further pointed out that PSE discipline would have some opportunities to play a role. Finally, the future prospects, mainly some suggestions for future works, were put forward in the fourth part.

    Chemical processes and equipment
    Research progress and prospect on inherent safety assessment methods for chemical processes
    ZHU Jiaxing, HAO Lin, LIU Guozhao, WEI Hongyuan
    2022, 41(8):  4009-4024.  doi:10.16085/j.issn.1000-6613.2021-2004
    Abstract ( 229 )   HTML ( 43)   PDF (1472KB) ( 252 )  
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    Sustainability is the key to social, ecological and economic development. The development path of sustainable manufacturing requires a balance between environmental, social and economic aspects. Inherent safe design is one of the most effective ways to reduce risk to achieve sustainable development of chemical industry. Inherent safe design can permanently eliminate or reduce the hazards involved in chemical processes. In this paper, an overview is presented covering the origins of inherent safety concept, its historical development, the concept of the four principles of inherent safety, the stages of application and potential use of the four principles of inherent safety throughout the life cycle of the process industry, and methods for inherent safe design assessment. The research progress and problems of inherent safe design assessment methods are introduced, which includes parameter-based score inherent safety assessment methods, parameter-based numerical inherent safety assessment methods, graph-based inherent safety assessment methods, risk analysis-based safety assessment methods and multi-objective-based inherent safety assessment method. The advantages and disadvantages of various methods are analyzed and compared and the future development and improvement of those methods were also commented.

    Effect of local erosion on flow field and separation performance of α-type cyclone separator
    FAN Junling, HE Hao, ZHANG Pan, CHEN Guanghui
    2022, 41(8):  4025-4034.  doi:10.16085/j.issn.1000-6613.2021-2031
    Abstract ( 76 )   HTML ( 6)   PDF (6818KB) ( 202 )  
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    Flow field and erosion characteristics of α-type cyclone separator were numerically simulated by Reynolds stress model (RSM), particle discrete phase model (DPM) and E/CRC erosion equation based on Eulerian-Lagrangian approach. Effect of local erosion on flow field and separation performance of the equipment was studied by analyzing the distribution rule of velocity vector, tangential velocity and particle trajectory. The results showed that the erosion in the wall opposite to the α-type cyclone separator inlet was the most serious, and the maximum erosion rate was about 1.4×10-5kg/(m2·s). The change of wall geometry caused by erosion led to deflection of airflow direction, which was not conducive to the stability of the main stream and the separation of solid particles. With the intensification of local erosion, the short-circuit flow at the inlet of the vortex finder increased sharply, resulting in a decrease in fluid flow in the area below the inlet of the vortex finder and a decrease in the tangential velocity of the outer vortex. The escape phenomenon of fine particles was more obvious, and the movement trajectory of coarse particles tended to coincide, and it was easier to form a high-concentration ash ring to aggravate the erosion of the wall. Compared with the condition without erosion, when the local erosion thickness was 50mm, the particle separation efficiency of 3μm particles decreased from 74.38% to 54.97%, the cut off diameter increased from 0.73μm to 2.36μm, and the pressure drop of the equipment decreased by about 15.41%. The research results provide a theoretical guidance for industrial application of cyclone separators.

    Analysis of fly ash deposition blockage mechanism and structure optimization of low temperature economizer
    FU Shuangcheng, CAO Gang, CHEN Qiangfei, SUN Xiaorun, OU Guofu, ZHOU Faqi, LI Luyu
    2022, 41(8):  4035-4046.  doi:10.16085/j.issn.1000-6613.2021-1944
    Abstract ( 56 )   HTML ( 6)   PDF (14197KB) ( 255 )  
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    In response to the occurrence of fly ash deposition blocking the furnace tube gap in low-temperature economizer of thermal power plants, the particle deposition behavior was analyzed using a shear transfer (SST) k-ω turbulence model and a discrete particle model (DPM). The deposition dynamics near the support beam in the economizer was predicted, and then the fin arrangement structure above the support beam was optimized and flow field was analyzed. The results showed that fly ash particles were deposited on the upper surface of the support beam due to the presence of the support beam and the upper fins in the coal economizer. Under denitrification conditions, ammonium bisulfate increased the adhesion between the fly ash. This aggravated the adhesion deposition, and thus the ash accumulation grew upwards and caused blockage. By changing the structure of the fin arrangement above the support beam, the flue gas flow pattern near the support plate was changed. For most of the fly ash particles (dp>40μm) in the flue gas, the inertial effect dominated and had a large impact rate with the wall. By changing the arrangement of the fins on the furnace tube, the ability of the fly ash particles to move laterally was increased, which has a better effect on the deposition blockage on the support beam.

    Coal gasification fine slag vacuum dewatering by ceramic membrane and numerical simulation
    GUO Fanhui, WU Jianjun, ZHANG Haijun, GUO Yang, LIU Hu, ZHANG Yixin
    2022, 41(8):  4047-4056.  doi:10.16085/j.issn.1000-6613.2021-2152
    Abstract ( 57 )   HTML ( 2)   PDF (2738KB) ( 37 )  
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    Gasification fine slag (GFS) is the waste of coal gasification process and its efficient dewatering is a prerequisite for its resource utilization and reduction disposal. In this paper, the dewatering experiment and numerical simulation were carried out by using ceramic membrane vacuum filtration system. The gasification fine slag slurry concentration and subaqueous adsorption time affected the filter cake forming thickness, and the increase of filter cake thickness caused increasing water transport path, which extended the effective dewatering time. The dewatering rate value of filter cake dewatering process showed a non-linear decrease trend and there was a limit value of 40% for dewatering process, which was related to the physicochemical properties. When the vacuum degree was less than 0.08MPa, the “channel water” of GFS filter cake can be effectively removed at about 24s. In the Fluent numerical simulation, Euler model was selected to determine the resistance coefficient of ceramic membrane filter plate and GFS filter cake. The error between experimental value and simulation result of dewatering process was less than 5%, which confirmed the reliability of the model. The evolution laws of vacuum pressure field and water content distribution cloud diagram were analyzed during the GFS dewatering process. The results indicated that dewatering efficiency of fine gasification slag can be improved by increasing dewatering vacuum degree, decreasing filter cake thickness and increasing “channel water” ratio and GFS particles equivalent diameter. Moreover, the filtrate obtained from ceramic membrane vacuum dewatering system had high cleanliness and some indexes met the standard of industrial water. The results had guiding significance for improving the dewatering efficiency and reducing energy consumption of GFS dewatering process, which was in line with the policy goal of “Carbon peak and Carbon neutral” in China.

    Analysis of influence of oil shale in-situ mining on some groundwater index
    JI Dongli, YE Jiliang, HE Shaolin, YUAN Hongying, XU Longtan, LI Ruolin, WANG Shuai, SONG Yang, QI Zhibin, GE Yanbing
    2022, 41(8):  4057-4064.  doi:10.16085/j.issn.1000-6613.2021-2136
    Abstract ( 51 )   HTML ( 6)   PDF (1055KB) ( 61 )  
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    At present, the study of oil shale in-situ mining is mainly focused on exploitation technology and process, and there are few reports on the impact of groundwater environmental risk caused by exploitation, which can lay a foundation for the establishment of quantitative evaluation model of groundwater environmental risk level of oil shale in-situ mining. Firstly, the weight loss ratio, specific surface area, element and mineral composition of oil shale and pyrolysis residue with particle size ≤2mm produced at different pyrolysis temperatures, air atmosphere and 0.1MPa were analyzed. Secondly, the effects of oil shale in-situ mining on pH, chroma, sulfate, ammonia nitrogen and chemical oxygen demand (CODMn) of groundwater quality indexes were investigated through leaching experiments at different pyrolysis temperatures and leaching times. The results showed that there was a negative correlation between weight loss rate and specific surface area of oil shale. The groundwater quality indexes in the leaching liquid were mainly affected by the change of organic matter content, rock composition and the proportion of each element. Meanwhile, pH and chroma were affected by pyrolysis temperature and leaching time, and pyrolysis temperature had great influence on sulfate, ammonia nitrogen and CODMn. Oil shale in-situ mining has a certain influence on groundwater quality, and appropriate risk prevention measures should be taken during exploitation.

    Design and control of pressure-swing distillation for separating methyl acetate-methanol-ethyl acetate azeotropic system
    XIANG Sheng, WANG Chao, ZHUANG Yu, GU Siwen, ZHANG Lei, DU Jian
    2022, 41(8):  4065-4076.  doi:10.16085/j.issn.1000-6613.2021-2059
    Abstract ( 76 )   HTML ( 4)   PDF (4971KB) ( 101 )  
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    The methyl acetate-methanol-ethyl acetate azeotropic mixtures can be produced in the production process of polypropylene alcohol, which must be treated immediately to avoid the environmental pollution and resource waste. In this paper, two pressure-swing distillation (PSD) separation sequences with different product orders were designed for the separation of methyl acetate-methanol-ethyl acetate mixture, which were economically optimized to obtain the optimal design parameters with the minimal total annual costs as target using genetic algorithm. The results showed that the equipment investment costs were 5.6×105USD/a and 5.7×105USD/a, and the energy costs were 8.8×105USD/a and 1.0×106USD/a for two PSD separation sequences, respectively. In addition, the control structures of the PSD scheme with economic advantages were constructed, so that the PSD process could remain stable and the purities of the three products after stabilization could still maintain near the initial set values in the face of feed flowrates and compositions disturbances.

    Molecular dynamics simulation on adsorption and dehydration behavior of calcium carbonate on heat exchange surface
    XIAO Yi, WANG Bingbing, YU Xuliang, WANG Xin, CAI Hanyou
    2022, 41(8):  4077-4085.  doi:10.16085/j.issn.1000-6613.2021-1943
    Abstract ( 53 )   HTML ( 5)   PDF (3829KB) ( 35 )  
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    Calcium carbonate fouling has a higher thermal resistance, and deposition of calcium carbonate on the heat exchange surface will lead to the reduction of heat exchanger efficiency, thus the formation and suppression of calcium carbonate are the focus of heat exchanger design. In this work, molecular dynamics method was adopted to analyze the adsorption and dehydration behavior of calcium carbonate on the copper metal surface in supersaturated calcium carbonate solution. The results showed that Ca—C coordination number firstly increased and then approached a constant value during the adsorption process of calcium carbonate to the surface, while the ion hydration number firstly decreased and then approached a constant value. The structure of calcium carbonate adsorbed on the metal surface did not changed significantly, and calcium carbonate was an amorphous structure with a certain hydration number. Increasing the surface temperature, the dehydration of the calcium carbonate was more complete, coordination numbers of Ca—C and Ca—O become higher, and the calcium carbonate adsorbed on the high-temperature surface transforms from a hydrated structure to anhydrous crystals. When the surface temperature was 800K, the ion hydration number was close to 0, and the Ca—O coordination number was approximate 6, which was close to the Ca—O coordination number of anhydrous calcium carbonate crystals at the macro scale.

    Energy processes and technology
    Research progress of non-aqueous solvents on the pretreatment of lignocellulose
    HAN Mingyang, QIAO Hui, FU Jiaming, MA Zewen, WANG Yan, OUYANG Jia
    2022, 41(8):  4086-4097.  doi:10.16085/j.issn.1000-6613.2021-1969
    Abstract ( 76 )   HTML ( 8)   PDF (512KB) ( 203 )  
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    Lignocellulose is the most abundant renewable resource in China. However, the intertwined complex structures prevent further conversion of cellulose and hemicellulose inside, which makes researchers seek effective pretreatment methods to solve the current problem. With the continuous discovery of solvents for biomass pretreatment and the emergence of new solvents, non-aqueous solvent pretreatment as an emerging pretreatment method has shown good effects and application prospects in the biorefinery of lignocellulosic raw materials. In this paper, based on introducing the physicochemical properties of various non-aqueous solvents, recent advances on the effect of these solvents on the pretreatment of lignocellulose, including the performance for hemicellulose and lignin removal and their influence on enzymatic hydrolysis are reviewed. The main advantages and disadvantages of different non-aqueous solvent pretreatment are also summarized. Furthermore, the challenges and future development directions of non-aqueous solvent pretreatment are proposed, which would provide references and guidance for future green, low-cost and efficient pretreatment methods.

    Progress and challenges of electrochemical synthesis of ammonia from different hydrogen and nitrogen sources
    GUAN Haoran, ZHU Lina, ZHU Lingyue, YUAN Dandan, ZHANG Yuqing, WANG Baohui
    2022, 41(8):  4098-4110.  doi:10.16085/j.issn.1000-6613.2021-2178
    Abstract ( 99 )   HTML ( 8)   PDF (2015KB) ( 649 )  
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    Ammonia is a primary chemical for the synthesis of basic organic chemicals and fertilizers. The Haber-Bosch process is employed in industry to synthesize ammonia, which not only uses a lot of energy but also has a low conversion of only 10% to 15%. Electrochemical ammonia synthesis has the advantages of clean production and gentle reaction conditions as compared to the Haber-Bosch process. The features and benefits of electrochemical ammonia synthesis using nitrogen, nitrate, and nitric oxide as nitrogen sources are discussed, and the reaction mechanisms are studied based on the properties of these nitrogen sources. Different hydrogen supply schemes and hydrogenation methods are described and evaluated based on the diverse nitrogen sources, and the research development of reaction catalysts is systematically summarized. Problems of the electrolytic systems such as poor solubility of nitrogen in water, nitrates with too many valence states, excessive intermediates, instable nitrogen oxide system, and competing hydrogen evolution reaction, are discussed in detail. Some suggestions for them are proposed which include altering the composition or structure of the hydrogen source to prevent hydrogen evolution, developing new catalyst systems with high active sites and oxygen vacancies to improve reaction selectivity, and developing non-aqueous electrolyte systems to improve reaction rate and synthesis efficiency.

    Analysis of the methane hydrate decomposition kinetics through depressurization method by using a pilot-scale reactor
    WANG Yunfei, SUN Changyu, YU Xichong, LI Qingping, CHEN Guangjin
    2022, 41(8):  4111-4119.  doi:10.16085/j.issn.1000-6613.2021-2010
    Abstract ( 49 )   HTML ( 0)   PDF (1501KB) ( 185 )  
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    A pilot-scale reactor with a volume of 196L was adopted to examine the decomposition behavior of hydrate reservoir which contains a bottom gas-rich zone. Exploitation experiments with a single vertical well, and with double well (vertical and horizontal well) were conducted. Results showed that an excessive pressure drop might result in well blocking by the ice which was resulted from foam entrainment. For reservoir with a bottom gas-rich zone, the areas closer to the well and the bottom of the reactor had a greater temperature drop, compared to other areas of the reactor owing to the faster local gas flow rate. The classical decomposition dynamics model was established. Results showed that for the large three-dimensional device, the driving force and decomposition rate could not reflect the actual hydrate decomposition behavior accurately. However, after the driving force was corrected through the residual ration of hydrate, the driving force had a linear relationship with the decomposition rate, and fitting parameters of single well experiment that k=0.284mol/(min·MPa) and double well experiment that k=0.279mol/(min·MPa) can be mutually verified.

    Experimental simulation of depressurization mining of the class 1 hydrate reservoir
    HUANG Ting, LI Qingping, LI Rui, PANG Weixin, CHEN Guangjin
    2022, 41(8):  4120-4128.  doi:10.16085/j.issn.1000-6613.2021-2124
    Abstract ( 35 )   HTML ( 1)   PDF (1893KB) ( 104 )  
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    Hydrate reservoirs containing underlying free gas in the South Sea have the geological conditions to realize the “two-gas production” of underlying free gas and hydrate decomposition gas, which can increase the gas production of hydrate mining and improve economic efficiency. However, there are few indoor experimental simulation studies on this type of reservoir, and there is insufficient understanding of the mining law. In this paper, a three-dimensional hydrate simulation device was developed to establish a new method for the preparation of the first type of hydrate reservoir containing free gas layers, and to study the gas and water production characteristics of the hydrate reservoir during the depressurization production process. The results showed that the production pressure below the four-phase point of methane hydrate could effectively accelerate the hydrate decomposition process and improve the mining efficiency. When the production pressure was reduced from 2.95MPa to 2.14MPa, the gas recovery rate in the rapid gas production stage was increased by 10%, the total mining time was shortened by about 38%, and the total recovery rate was increased from 73% to 81%. When the production well hole was located in a hydrate layer, secondary hydrate formation may occur near the well hole, resulting in a significant reduction in the rate of gas production. Compared with the production well in a gas layer, with the same cumulative gas production rate, the production time was extended by about 30%. Comparing the first and third types of hydrate reservoirs, the rapid gas production phase of the first type hydrate reservoir lasted for more than 20min, which was more than twice as long as that of the third type hydrate reservoir, but the total gas recovery rate was slightly lower. The first type of gas-saturated hydrate reservoir was modeled here, and to simulate actual marine hydrate reservoir, it had certain limitations. Future research will need to focus on the scale of experimental equipment, regional temperature control methods, experimental media selection, and reservoir remodeling stability. So that we can solve the key technical problems of reservoir remodeling to provide basic data reference for the mining of argillaceous silt-type natural gas hydrate reservoirs with underlying free gas in our country.

    Gravity effect on PCM melting process under constant heat flux boundary
    ZHANG Chunwei, LI Shanfeng, GUO Yongzhao, ZHANG Xuejun, JIANG Long
    2022, 41(8):  4129-4139.  doi:10.16085/j.issn.1000-6613.2021-2086
    Abstract ( 44 )   HTML ( 1)   PDF (3432KB) ( 144 )  
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    To improve the melting rate of PCM in latent heat storage unit, a universal coordinate based on the heat source input direction and gravity direction was defined, and a visual experimental device and corresponding mathematical model were established to investigate the effect of the included angle γ on the melting of PCM in the square cavity under the constant heat flux boundary. The results showed that when the included angle γ increased from 0° to 180°, the melting time first increased, then decreased, and rise slightly again. When the included angle γ was 0°, the heat transfer in PCM was only heat conduction. When the included angle γ was 15°, the melting time was the longest and increased by 40.32% compared with that of the single heat conduction process. When the included angle γ was 120°, the melting time was the shortest and reduced by 63.11% compared with that of the single heat conduction process. Therefore, when the included angle is small, natural convection has an inhibitory effect on the PCM melting. Only when the included angle γ is greater than a certain value, could natural convection promote the PCM melting. Also, the optimal included angle γ obtained under different working conditions was between 90° and 180°, and relatively close to 90°. Therefore, the lowest point on the heat source side should be lower than that on the PCM side for the regular latent heat storage unit in practical engineering applications.

    Influence of molar ratio of silicon to calcium on mineral evolution and ash melting characteristics during the combustion process of Zhundong coal
    WANG Guangxu, JIN Jing, ZHANG Yunpeng, LIU Bojianzhi, LIANG Shiyu, ZHAI Zhongyuan
    2022, 41(8):  4140-4146.  doi:10.16085/j.issn.1000-6613.2021-1960
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    Selecting the Zhundong high-calcium Wucaiwan (WCW) coal as the research object, the coal ash melting characteristics and mineral evolution were studied by changing the molar ratio of silicon to calcium (M) in coal ash, and the mineral balance was predicted by using FactSage thermodynamic calculation software. The results showed that in WCW raw coal ash, mineral CaSO4 evolved into mineral Ca2MgSi2O7 with low melting point, which made the prediction of slagging and fouling of raw coal ash by ash melting temperatures (AFTs) had a great deviation. For mixed coal ash, when M increased to 3, compared with raw coal ash, CaSO4 was decomposed earlier, and SiO2 reacted with CaO preferentially to generate CaMgSi2O6 mineral with lower melting point, thus causing the melting point of mixed coal ash to decrease. When the M in coal ash increased to 5, sufficient SiO2 will react with MgO to generate the high melting point mineral Mg2SiO4, which significantly improved the AFTs of mixed coal ash at this moment and improved the coal ash fusion characteristics. The results of thermodynamic calculation of mineral equilibrium agreed well with X-ray diffraction analysis (XRD) , and the Gibbs free energy results verified the rationality of mineral evolution process.

    Industrial catalysis
    Progress in the degradation of organic pollutants by H2O2/PMS/PDS activated by transition metal single-atom catalysts
    DUAN Yi, ZOU Ye, ZHOU Shukui, YANG Liu
    2022, 41(8):  4147-4158.  doi:10.16085/j.issn.1000-6613.2021-2140
    Abstract ( 92 )   HTML ( 11)   PDF (1493KB) ( 62 )  
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    Single-atom catalysts (SACs) are a new type of material that can load metal on the carrier in atomic state. They have the advantages of high atom utilization, strong catalytic activity and easy recovery, so they have attracted much attention in the catalytic degradation of organic pollution. In this work, the influencing factors of SACs were introduced, and the applications of SACs in environmental field for catalytic degradation of organic pollutants are summarized. In addition, the catalytic mechanisms of SACs of different transition metals (Fe, Co, Mn, Cu, etc.) in advanced oxidation technology based on hydrogen peroxide or persulfate are reviewed. Single-atom metal (M) generally bonds with N to form the active site M—N x, which activates the oxidant to generate radicals or singlet oxygen, and effectively degrades organic pollutants. Finally, the research directions of SACs on the catalytic degradation of organic pollutants are the preparation of SACs of high metal loading, high stability and wide range of pH, and the design of specific catalysts for different target pollutants according to the structure-performance relationship and catalytic mechanisms of SACs.

    Progress of metal oxide in OX-ZEO catalyst for CO x hydrogenation to light olefins
    ZHANG Peng, MENG Fanhui, YANG Guinan, LI Zhong
    2022, 41(8):  4159-4172.  doi:10.16085/j.issn.1000-6613.2022-0422
    Abstract ( 95 )   HTML ( 17)   PDF (5301KB) ( 214 )  
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    Metal oxide-zeolite (OX-ZEO) bifunctional catalyst can convert CO x hydrogenation into light olefins with high selectivity. In this work, the progresses of metal oxide in OX-ZEO catalyst for CO x hydrogenation to light olefins are summarized, the advantages of “relay catalysis” are expounded through the thermodynamic analysis of CO x hydrogenation to methanol/ethylene reaction, and the type and composition of metal oxide, OX-ZEO preparation method and the influence of “proximity” between oxide and SAPO-34 are mainly discussed. The catalytic reaction mechanism, the role of oxygen vacancy and the strategy to suppress side reactions are discussed. The problems and challenges of the OX-ZEO catalytic route are analyzed, and the development trend of the OX-ZEO catalytic system is prospected. It is believed that the catalytic activity can be improved by increasing the oxygen vacancies of metal oxides through elemental doping, promoter modification or optimizing preparation conditions, etc. Moreover, the by-product CO2 generation can be suppressed by hydrophobic surface modification of the metal oxides to improve the utilization of C atoms.

    Effect of cosolvent in activation solution on regenerated denitration catalysts
    MA Jing, MA Ziran, LIN Dehai, MA Shaodan, WANG Baodong
    2022, 41(8):  4173-4180.  doi:10.16085/j.issn.1000-6613.2021-2559
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    The deactivated denitration catalysts used in a coal-fired power plant were washed and then immersed in activation solutions with oxalic acid and ethanolamine respectively as cosolvents for investigating the regeneration effect. The fresh, deactivated, and two regenerated catalysts were analyzed with XRF, N2-physisorption, in-situ pyridine adsorption, NH3-TPD, Raman, XPS, H2-TPR, and then were tested in a fixed bed denitration catalytic reactor. The major deactivation of denitration catalysts was because that the K, Na from fly ash caused loss of specific surface area, pore volume, Lewis acid sites, active VO x species, and ratio of V5+, and weakened the catalysts’ oxidation-reduction ability. Meanwhile, the two regenerated catalysts with the same vanadium content showed great difference on the denitration efficiencies. Ethanol-cat, regenerated by ethanolamine-assisted activation solution had denitration efficiency over 97% of that of the fresh catalyst. However, Oxalic-cat, regenerated by oxalic acid-assisted activation solution showed almost no regeneration effect. This was due to the vanadium species with different states in the two activation solutions. The vanadium species in ethanolamine-assisted activation solution could recover Lewis acid sites, ratio of V5+ and active VO x species of the deactivated catalysts, and enhance the oxidation-reduction ability of catalysts effectively, but the vanadium species in oxalic acid-assisted activation solution could hardly attain these results.

    Hydrothermal preparation of 3D flower-spherical Bi2SiO5 for photocatalytic esterification of oleic acid
    CHANG Yaoping, GUAN Xiushuai, ZHENG Qian, JIN Shanbiao, ZHANG Changming, ZHANG Xiaochao
    2022, 41(8):  4181-4191.  doi:10.16085/j.issn.1000-6613.2021-2161
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    The fossil fuel depletion and environmental pollution have made the search for sustainable and renewable energy sources (e.g. biofuels) become a world focus. In this paper, 3D flower-spherical Bi2SiO5 was prepared via a simple hydrothermal method and used for the photocatalytic esterification of oleic acid with methanol under simulated sunlight irradiation. To understand the physical, chemical and optical properties of Bi2SiO5 catalyst, the as-prepared samples were characterized by XRD, XPS, SEM, HRTEM, NH3-TPD and UV-vis DRS, and the compositions of reaction products were analyzed by FTIR. The yield of methyl oleate as the esterification product was quantified by 1H NMR, due to the simple calculation and accurate and reliable results. Under simulated sunlight irradiation, the optimum reaction conditions were 12:1 alcohol to oil ratio, 5% catalyst, 70℃ and 6h, under which the yield of methyl oleate was 28.8%. The 1H NMR analysis showed that the selectivity of methyl oleate was as high as 100% and the yield of methyl oleate was still 26.8% after three recycles of catalyst. ESR tests confirmed the existence of hydroxyl radical (·OH) and superoxide radical (·O2-) in the reaction. As the first application of Bi2SiO5 in photocatalytic esterification, a possible reaction mechanism was proposed to explain the relative catalytic activity.

    Synthesis of heteroatom-substituted beta zeolites for catalytic epoxidation of cyclic olefins
    WU Yushuai, YOU Qing, DONG Xujie, ZHU Ziqi, WANG Xu, CHEN Huiyong, MA Xiaoxun
    2022, 41(8):  4192-4203.  doi:10.16085/j.issn.1000-6613.2021-2097
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    Four types of heteroatom-substituted beta zeolites were prepared by a post-synthetic method. Nanosized Al-beta was used as the dealumination substrate, followed by the incorporation of 4—6 transition-metal atoms (W, Mo, V, and Ti) into the framework of dealuminated beta. The obtained heteroatom-substituted beta zeolites (W-beta, Mo-beta, V-beta, and Ti-beta ) well inherited the high crystallinity, large micropore volume and nanoparticle morphology from their parent Al-beta. However, the incorporation amounts of various heteroatoms were different due to the discrepancy in ion radiuses and M—O bond lengths, and V-beta, and Ti-beta showed much higher metal contents than W-beta and Mo-beta. The beta zeolites were further used as catalysts for the epoxidation of cyclohexene and cyclooctene. W-beta and Mo-beta revealed lower conversions of cyclic olefins but higher turnover frequency (TOF) values than V-beta and Ti-beta, indicating the higher activities of the W and Mo active sites. V-beta exhibited the highest conversion of cyclohexene due to its high content of V, but the epoxide selectivity over V-beta was much lower than that over the other heteroatom-substituted beta catalysts, which could be ascribed to the excess oxide species that promoted the side reaction of allylic oxidation. Besides, serious leaching of V species were observed for the V-beta catalyst that led to a poor recyclability in liquid-phase epoxidation reaction. Among all the heteroatom-substituted beta catalysts, Ti-beta exhibited the highest conversion and epoxide selectivity in the catalytic epoxidation of cyclic olefins. Moreover, the Ti active species in Ti-beta were quite stable, which further gave a superior recyclability of Ti-beta. In addition, the conversion of cyclic olefins over Ti-beta can be enhanced by increasing the content of Ti, but the excess Ti species tend to form the low-activity oxides and reduce the TOF value.

    Nitrogen-sulfur doped biochar/permonosulfate for degradation of sulfisoxazole in water
    PAN Jie, WANG Mingxin, GAO Shengwang, XIA Xunfeng, HAN Xue
    2022, 41(8):  4204-4212.  doi:10.16085/j.issn.1000-6613.2021-2197
    Abstract ( 46 )   HTML ( 0)   PDF (2627KB) ( 20 )  
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    A series of N and S doped and modified biocarbon fiber materials NSC-X were synthesized by high-temperature pyrolysis. The samples were characterized by various techniques. Sulfisoxazole (SSX) was selected as for degradation in water, and the degradation effect and mechanism of SSX by NSC-X activated peroxysulfate (PMS) were studied. The experimental results showed that the doping of N and S elements significantly improved the degradation performance of the activated PMS. The catalytic performance of NSC-5 was the best. When the dosage of NSC-5 was 0.4g/L and the PMS and SSX concentrations were 0.25mmol/L and 10mg/L, more than 80% of SSX was removed after 90 minutes of reaction, and the reaction rate was 2.7 times of that with biological carbonaceous material (BC) involved in the reaction. Electron paramagnetic resonance (EPR) showed that the main active species in the degradation included singlet oxygen (1O2), sulfate radical (·SO4-) and hydroxyl radical (·OH). The doping of nitrogen and sulfur accelerated the electron transfer rate, thereby increasing the catalytic activity of the materials.

    Effect of CeO2 morphology on the performance of CuO/CeO2 catalyst for CO2 hydrogenation to methanol
    ZHANG Jiaqi, LIN Lina, GAO Wengui, ZHU Xing
    2022, 41(8):  4213-4223.  doi:10.16085/j.issn.1000-6613.2021-1977
    Abstract ( 48 )   HTML ( 3)   PDF (4295KB) ( 271 )  
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    CeO2 nanoparticles(W-CeO2), CeO2 nanosheets(S-CeO2), CeO2 nanorods(B-CeO2) and CeO2 nano-octahedra(O-CeO2) were firstly prepared by hydrothermal method, and then CuO/CeO2 catalysts with fixed copper mass fraction were obtained by impregnation method. The catalysts were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), automated adsorption analyzer (BET), H2 programmed temperature rise reduction (H2-TPR), N2O titration and other characterization techniques, and their catalytic performance was assessed in a fixed bed quartz tube reactor with controlled temperature and pressure. The effects of the CuO/CeO2 catalyst morphology on the methanol production by CO2 hydrogenation were investigated. The catalytic activity of the CuO/CeO2 catalysts showed a strong dependence on their morphology, and the factors of the exposed crystalline surface, specific surface area, surface basic sites and surface oxygen defects of the catalysts all affected the CO2 conversion, methanol selectivity and the yield. Among them, the order of the activity of the preferentially exposed crystalline surfaces of CeO2 with different morphologies is S-CeO2({100}+{110})>W-CeO2{100}>B-CeO2{111}≈ O-CeO2{111}). The higher the activity of the exposed crystalline surfaces, the more oxygen defects on the catalyst surface, and the stronger the CuO/CeO2 interactions, the better the catalytic activity. Regarding CuO/S-CeO2, it had the most basic sites on the surface with a specific surface area of 88.8m2/g and copper dispersion of 19.2%, giving the best catalytic activity of CO2 conversion 6.56%, methanol selectivity 96.3% and yield 0.063g/(gcat·h). The activity evaluation tests showed the conversion rates of the catalysts were in the order of S-CeO2>B-CeO2>W-CeO2>O-CeO2, which indicates that the CeO2 morphology could determine the physical and chemical properties and the catalytic activity of the CuO/CeO2 catalysts.

    Materials science and technology
    Research progress in benzoxazine resin
    ZU Liwu, BI Ying, ZHAO Binhui, LI Jidong, YANG Qing, CONG Shanshan
    2022, 41(8):  4224-4240.  doi:10.16085/j.issn.1000-6613.2021-1947
    Abstract ( 51 )   HTML ( 12)   PDF (3313KB) ( 336 )  
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    Polybenzoxazine(PBZ) as a class of heterocyclic polymers are ranked as materials of superb thermal stability, extremely high tensile strength and good chemical resistance, which has been applied in many fields such as aerospace composites, blends and electronic circuit boards. In this paper, three routes and synthesis methods for preparing BZ monomer are reviewed, and the mechanism of cationic ring-opening polymerization (ROP) of benzoxazine (BZ) monomer without catalyst is summarized. Functionalized BZ monomers with containing addition-curable sites are categorized, and the influence of curable groups on the properties of PBZ is mainly discussed. Similarly, the structure, properties and research status of functionalised BZ with varying structural features but no additional polymerisable groups are investigated in detail. By molecular design, the monofunctional, difunctional and polymerisable group-substituted BZ is prepared, as well as high-molecular-weight PBZ and main-chain BZ novice materials. The research progress of BZ composites is introduced. The shortcomings of PBZ resin, such as high processing temperature and high brittleness of classical PBZ, and the reasons are pointed out. Finally, the development direction of benzoxazine resin in the preparation of green bio-based BZ, the modification of PBZ composite material and the synthesis of functional BZ with new structure are prospected.

    Research progress of molecular simulation technology in the development and application of chitosan functional materials
    FENG Ying, ZHAO Mengjie, CUI Qian, XIE Yuju, ZHANG Jianwei, DONG Xin
    2022, 41(8):  4241-4253.  doi:10.16085/j.issn.1000-6613.2021-2176
    Abstract ( 55 )   HTML ( 3)   PDF (3512KB) ( 35 )  
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    Chitosan is widely used in medicine, energy, environmental protection and other fields because of its excellent biocompatibility, renewability, biodegradability, flocculation and adsorption. With the rapid development of computer science and quantum chemistry, the application of molecular simulation to the development and application of chitosan materials has become a hot spot. In this paper, the research progress of molecular simulation technology in this field in recent years was reviewed, the basic methods and characteristics of molecular simulation were summarized, and the common modules and applications of quantum chemistry based molecular simulation software Materials Studio in chitosan research were described in detail. On this basis, the analysis and prediction of molecular structure, micro reaction mechanism and compatibility of chitosan by molecular simulation, as well as the research progress of molecular simulation of chitosan in the fields of biomedical materials, fuel cell, corrosion inhibitor and water treatment were introduced. The advantages of molecular simulation method in the development and application of chitosan functional materials and the shortcomings in the exploration of micro mechanism were summarized and analyzed. The research methods of using multi-scale simulation and combining with machine learning to improve the accuracy and calculation speed of simulation results were proposed, which provided a new idea for the design and development of new chitosan materials in the future.

    Progress in water stable and water absorption applications of metal-organic frameworks
    ZU Mei, XU Haitao, XIE Wei, CHENG Haifeng
    2022, 41(8):  4254-4267.  doi:10.16085/j.issn.1000-6613.2021-2040
    Abstract ( 67 )   HTML ( 8)   PDF (3927KB) ( 410 )  
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    Water vapor is widely present in air and industrial gases and its collection and removal requires the use of adsorbents with high water absorption and storage capacity. Metal-organic frameworks (MOFs), as a new type of porous material with high porosity and high specific surface area, have the characteristics of both mesh structure and controlled pore size adjustment, and are widely studied in various fields such as adsorption, separation, catalysis and filtration. The application of MOFs in water adsorption requires not only high-water stability, but also hydrophilic and adsorption-desorption cycle capabilities. This paper reviewed the basic composition of water-stable MOFs, the design principles based on Pearson’s soft and hard acid-base theory, the factors influencing the water adsorption behavior and the progress of applications such as air water harvesting and gas dehumidification. The physical parameters of 13 water adsorption MOFs and their derivatives with reference to the saturation moisture absorption were listed. Finally, the problems in the synthesis mechanism, batch preparation and application of water adsorption MOFs were summarized, and the corresponding solutions were proposed, which were expected to provide valuable references for the research direction of MOFs in water adsorption applications.

    Review and perspective of gas sensing application based on polydiacetylene
    GE Mingliang, HE Ziyu
    2022, 41(8):  4268-4276.  doi:10.16085/j.issn.1000-6613.2021-2094
    Abstract ( 34 )   HTML ( 1)   PDF (1625KB) ( 172 )  
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    The mechanism of polydiacetylene as gas sensing material was analyzed in this paper. The principle of gas sensing performance enhancement, advantages, as well as existing problems were clarified in reference to the reinforcing material, i.e., polyurethane, graphene, molybdenum disulfide and cellulose nanocrystalline. The application of new sensors such as food spoilage detection and portable wrist sensor was also introduced. Polydiacetylene as gas sensing material was still in its infancy. Some problems needed to be solved urgently, such as the lack of clarity about the mechanism of optical transformation, cumbersome side chain modification process, limited choice of functional groups and vulnerability to lose efficacy. The selection of reinforcement materials should be expanded and the structure of composite should be adjusted to achieve high selectivity and sensitivity response to the measured gas in future studies. It was necessary to make good use of the advantages of simple molding process and good compatibility with the environment of polydiacetylene composite to prepare more functional gas sensing materials.

    Research progress on countermeasures for microcrack-induced capacity degradation of Ni-rich cathode materials
    LI Xiang, GE Wujie, MA Xianguo, PENG Gongchang
    2022, 41(8):  4277-4287.  doi:10.16085/j.issn.1000-6613.2021-2138
    Abstract ( 36 )   HTML ( 2)   PDF (3990KB) ( 15 )  
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    With the wide application of lithium-ion batteries in the fields of electric vehicles and energy storage, the demand for cathode materials, especially lithium cobalt oxide, lithium nickel-cobalt-manganese oxide and lithium nickel-cobalt-aluminum oxide cathode materials, have increased dramatically. However, due to the scarcity of cobalt resources, “Ni-rich and Co-poor” has become an important concern and direction of development of the lithium-ion battery industry in recent years. Ni-rich cathode materials (Ni mole content higher than 60%) have attracted wide attention due to the advantages of high energy density and cost efficiency, and the pace of industrialization of the materials has accelerated over time. The conventional spherical Ni-rich cathode materials are faced with the problem of rapid capacity fading caused by microcrack formation due to anisotropic volume change. The problem is considered as the dominant factor of capacity fading of spherical Ni-rich cathode materials. In this paper, several strategies to deal with this problem in recent years are reviewed, including interstitial coating, design and synthesis of radially ordered primary particles, and the use of Ni-rich single-crystal cathode materials. These methods are analyzed, evaluated and summarized in detail, and further research direction is prospected.

    Research progress of low-carbon hydrocarbon(C1~C3) separation based on MOFs
    ZHANG Yuke, LIU Qian, DUAN Yuanyuan, ZHAO Yingjie, CUI Yang, SHI Lijuan, LI Xiangyuan, LI Jianchuan, FAN Haiming, YI Qun
    2022, 41(8):  4288-4302.  doi:10.16085/j.issn.1000-6613.2021-2037
    Abstract ( 48 )   HTML ( 0)   PDF (2841KB) ( 26 )  
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    The separation and purification of low molecular weight hydrocarbon (C1—C3) mixtures is a critical and energy-consuming industrial process. Therefore, it is imminent to develop solid adsorption materials that can selectively adsorb and separate C1—C3 molecules with low energy consumption under mild conditions. As a relatively novel class of porous organic-inorganic hybrid materials, metal-organic frameworks (MOFs) have received extensive concerned in the field of low-carbon hydrocarbon separation and purification due to its precisely controllable pore structure and diverse chemical microenvironment. This work outlined the characteristics of MOFs as adsorbents for the separation and purification of low-carbon hydrocarbon gases. The focus was on the application progress of MOF materials in the separation of C1 (CO2/CH4), C2 and C3. The three common separation mechanisms of MOFs materials in the separation of C1—C3 hydrocarbons were summarized firstly, and then the adsorption and separation performance of MOFs materials for common C1—C3 hydrocarbon molecules in recent years were reviewed accordingly. The structure-activity relationship of MOFs in the separation of C1—C3 hydrocarbons was analyzed. The control concepts and methods of the pore size/shape, skeleton flexibility and surface function of MOFs materials were summarized. The high cost of MOFs materials, poor hydrothermal stability, and the difficulty of precise detection of the relationship between the host and the object were proposed, which restricted their application and development. Future research should be focused on developing low-cost, diversified and specific new ligands, constructing composite adsorbents, and clarifying the host and guest properties of the separation system during the adsorption and separation process. It would provide an exploration direction for the directional design of MOFs materials for the low-carbon hydrocarbons separation.

    Progress on superhydrophobic materials from nanocellulose
    ZHAN Xun, CHEN Jian, YANG Zhaozhe, WU Guomin, KONG Zhenwu, SHEN Kuizhong
    2022, 41(8):  4303-4313.  doi:10.16085/j.issn.1000-6613.2021-2005
    Abstract ( 48 )   HTML ( 1)   PDF (1998KB) ( 53 )  
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    Due to the abundant hydroxyl groups on the surface, nanocellulose has high hydrophilicity and water absorption, which has become the main factor affecting its large-scale application. Functional modification of the active hydroxyl groups on the surface of nanocellulose to improve its hydrophobicity has increasingly become an attractive research area. Based on a brief description of superhydrophobic materials and a comparison of different preparation methods of superhydrophobic materials, this article focused on the research progress on using nanocellulose to construct superhydrophobic materials (aerogels, paper, coatings and films) in the fields of biomedical, papermaking, oil-water separation, food packaging, energy storage materials, etc., and summarized and analyzed the problems in the application of nanocellulose superhydrophobic materials. At the same time, it was pointed out that the future development direction of nanocellulose to construct superhydrophobic materials would focus on the pollution-free process, process simplification and stability optimization.

    Research progress of metal organic framework/polyamide thin film nanocomposite membrane
    ZHU Xiao, ZHU Junyong, ZHANG Yatao
    2022, 41(8):  4314-4326.  doi:10.16085/j.issn.1000-6613.2021-1946
    Abstract ( 38 )   HTML ( 4)   PDF (2395KB) ( 28 )  
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    Compared to the traditional polyamide thin-film composite (TFC) membranes, metal-organic frameworks (MOFs)/polyamide thin-film nanocomposite (TFN) membranes exhibit higher perm-selectivity and show great potential for molecular and ion separation in industrial applications, which benefited from MOFs materials with high surface area, orderly and controllable pore structure, favored polymer affinity and customizable chemical function. This review first briefly introduced the research background of MOFs polyamide composite membrane, and then summarized the progress of MOFs polyamide composite membrane in terms of the characteristics of MOFs materials and the preparation strategy of MOFs polyamide composite membrane. The roles of physicochemical features of MOFs in the microstructure and separation performance of TFN membranes are discussed. Subsequently, various preparation strategies of MOFs doped polyamide membrane are introduced, and the loading efficiency of MOFs is analyzed. Finally, the application of MOFs polyamide composite membrane in gas and liquid system separation is briefly described. The stability of MOFs polyamide membrane in the application process is analyzed, and the future research of MOFs polyamide composite membrane in the optimization of MOFs load and functional design is prospected.

    Research progress on the fabrication and application of textile materials with photonic crystal structural colors
    CHEN Huanhuan, GAO Weihong, CHEN Kaikai, ZHANG Zhiyue, ZHAO Xiaoyan
    2022, 41(8):  4327-4340.  doi:10.16085/j.issn.1000-6613.2021-1959
    Abstract ( 33 )   HTML ( 0)   PDF (5026KB) ( 32 )  
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    In order to solve the problem that traditional chemical dyes and pigments with high pollution, high energy consumption and easy fading are widely used in textile printing and dyeing industry, the research progress in preparation and application of textile materials with photonic crystal structural colors in recent years was reviewed according to the characteristics of structural colors materials such as colorant free, bright color and not easy to fade. This paper introduced the structure of photonic crystal and its color generating mechanism, expounded the common preparation methods of textile materials with structural color, summarized the application of photonic crystal structural color in fiber, yarn, fabric and pigment, and analyzed the problems existing in the application process. The analysis showed that photonic crystal structural colors textile materials can achieve rapid preparation with large area. Constructing structural colors on fabrics was more convenient with more researches, while there were fewer studies on constructing structural colors on yarns. Constructing structural colors on fibers was easy to give them functionality and related research was gradually increasing. Finally, the problems in the application of photonic crystal structural colors to the textile field were summarized and the research direction was prospected.

    Research and application of electrospun nanofibers with special morphology: a review
    WANG Hui, LIU Xinyi, WANG Wei, WAN Tong, LI Zongjie, WANG Shaoyu, CHENG Bowen
    2022, 41(8):  4341-4356.  doi:10.16085/j.issn.1000-6613.2021-2016
    Abstract ( 32 )   HTML ( 3)   PDF (2734KB) ( 26 )  
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    Special morphology nanofibers were prepared with the in-depth study of the electrospinning technology and process mechanism. It had larger specific surface area and higher porosity than ordinary nanofibers, as well as the versatility given to fibers by doping with various organic/inorganic materials. Its research had penetrated into many fields such as energy and environment, catalytic filtration, bioengineering, food safety, etc., and it was one of the hotspots in the research of nanomaterials fields. However, there were still some problems need to be solved, such as imperfect research system, high difficulty in mass production, poor reproducibility and so on. In this review, the forming mechanism of special morphology nanofiber was highlighted, the unique morphological structure and excellent properties of special morphology nanofiber were summarized, and its application research in the fields of particle penetration, particle interception and transportation were reviewed in detail. In addition, the limitation of special morphology nanofibers was discussed from research and preparation to application. A complete research system for special morphology nanofibers should be established and the functional nanofiber membranes with special morphology should be also developed for various application fields to promote the industrialization of special morphology nanofibers from the perspective of environmental protection and stability.

    Research progress of erythritol phase change materials for thermal storage
    YANG Yukai, XIA Yongpeng, XU Fen, SUN Lixian, GUAN Yanxun, LIAO Lumin, LI Yaying, ZHOU Tianhao, LAO Jianhao, WANG Yu, WANG Yingjing
    2022, 41(8):  4357-4366.  doi:10.16085/j.issn.1000-6613.2021-2101
    Abstract ( 43 )   HTML ( 4)   PDF (3385KB) ( 29 )  
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    Erythritol, a type of medium temperature phase change material, has attracted considerable attention in thermal storage for its good comprehensive performance such as high enthalpy, non-toxicity and excellent thermal stability. However, its ubiquitous defects, such as easy leakage during its phase transition, severe supercooling and poor thermal conductivity, reduce the efficiency of thermal energy and limit its wide practical application. In this paper, the research progress in solving the problems of easy leakage, high supercooling and low thermal conductivity of erythritol phase change materials is reviewed in recent years. The methods for preparing shape-stabilized erythritol phase-change thermal storage materials mainly include blending pressing, electrospinning, microcapsule and porous material adsorption. Corresponding composite strategies can be implemented according to different preparation methods to achieve the purpose of package, supercooling reducing and enhancement of thermal conductivity. It is believed that the future research toward erythritol phase-change thermal storage materials not only focuse on thermal properties, but also considere multi-functionalization of erythritol phase-change materials for widening its applications.

    Structure and properties of PTFE membrane for high efficiency air filtration
    LIU Chaojun, LIU Junjie, DING Yike, ZHANG Jianqing
    2022, 41(8):  4367-4374.  doi:10.16085/j.issn.1000-6613.2021-1955
    Abstract ( 48 )   HTML ( 0)   PDF (1776KB) ( 31 )  
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    PTFE membrane high-efficiency air filter material has been widely used in the clean room of the electronics industry because of its high filtration efficiency, low-resistance and boron-free release. However, there is still a lack of systematic comparative research on the structure and performance of PTFE membrane/conventional filter. In this paper, two commercial PTFE membrane high-efficiency filter materials were selected, and the microstructure and filtration properties of the materials were compared comprehensively with those of ultra-fine glass fiber filter materials by means of scanning electron microscopy, pore size analyzer, automatic filter material tester and other characterization methods. The results showed that PTFE membrane was essentially a kind of fiber filter material, and its average diameter was about 60—85nm, which was much lower than 668.8nm of fiberglass filter. The filtration efficiency of PTFE membrane was comparable to that of fiberglass filter, and its initial resistance was 50% lower than that of fiberglass filter. However, the dust-loading performance of PTFE membrane was inferior to that of fiberglass filter, which made the former more suitable for situation equipped with regeneration or pre-filtration devices.

    Removal of methylchlorosilane in silicon-based electron gas by molecular dynamics simulation
    LI Yanping, YAN Dazhou, YANG Tao, WEN Guosheng, HAN Zhicheng
    2022, 41(8):  4375-4385.  doi:10.16085/j.issn.1000-6613.2021-2154
    Abstract ( 41 )   HTML ( 0)   PDF (1779KB) ( 28 )  
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    Optical fiber communication technology is a promising multi-channel communication means owing to the advantages of large communication capacity, low transmission loss and good security performance. As one of the related technologies, silicon-based electron gas SiCl4 is used to prepare optical fiber preform by chemical vapor deposition. But, the metal and hydrogen impurities in SiCl4 increase the absorption loss of optical fiber transmission due to the great vibration absorption of photons. In fact, the purity of SiCl4 for optical fiber is very high, and the content of methylchlorosilane should be reduced to 5mg/kg or less. So far, photochlorination combined with distillation is the most suitable method to prepare high purity SiCl4 for optical fiber. In this paper, reactive molecular dynamics simulation of the photochlorination process for the removal of methylchlorosilane impurities was carried out at the molecular level. At first, the removal effects of Cl2, Cl radical, as well as reaction temperature on methylchlorosilane were compared and analyzed. Then, the main intermediate products formed in different simulation systems and the main conversion paths were explored. This research provided the basic chemical reaction mechanism and process improvement direction for the photochlorination technology. The simulation results showed that the removal efficiency of methylchlorosilane could reach double times of that of Cl2 under the same simulation conditions when Cl radical was introduced into the reaction system. Besides, it was not monotonous of the relationship between the reaction temperature and the removal efficiency of methylchlorosilane. As a result, there was an optimal reaction temperature (373K) to maximize the removal efficiency of methylchlorosilane. The C—H bond and C—Si bond in methylchlorosilane molecule were difficult to break because of the large bond energy. For example, the C—H bond could be observed only when the reaction temperature in the system rose to a certain value (423K), and the C—Si bond can be observed only when the active Cl radical was introduced into the system.

    Microporous carbon modified separator for high performance lithium sulfur batteries
    JIN Wei
    2022, 41(8):  4386-4396.  doi:10.16085/j.issn.1000-6613.2021-2007
    Abstract ( 48 )   HTML ( 5)   PDF (5199KB) ( 27 )  
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    Owing to the higher energy density, lithium-sulfur batteries have become one of the most promising energy storage systems. However, the shuttle effect derived from polysulfide hiders its large-scale commercial application. To solve this problem, a unique microporous carbon (UMC) via facile pyrolysis to modify separator in lithium sulfur battery was synthesized. The UMC with a uniform pore size of 0.56nm had abundant nanopores, facilitating lithium ion transportation and ensuring the re-used of polysulfides on the cathode side. With a current density of 0.1C, the initial discharge specific capacity of the battery was 1359mAh/g and the capacity retained 966mAh/g after 100 cycles. It also delivered good capacitance retention of 88% after 500 cycles, indicating excellent cycling stability. On the contrary, the specific capacity of commercial PP was only 409mAh/g after 100 times.

    Preparation and electrochemical performance of bagasse-based phosphorus-doped activated carbon
    XIONG Yongzhi, LIU Yanyan, CHEN Xiaohong, LU Beili, HUANG Biao, LIN Guanfeng
    2022, 41(8):  4397-4405.  doi:10.16085/j.issn.1000-6613.2021-2056
    Abstract ( 38 )   HTML ( 0)   PDF (2061KB) ( 18 )  
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    Bagasse-based phosphorus-doped activated carbon was prepared with bagasse as carbon source and phytic acid as phosphorus source and activator, and applied to the field of supercapacitors. The effects of activation temperature and impregnation ratio on the iodine adsorption value, methylene blue adsorption value and electrochemical performance of activated carbon were analyzed. The mechanism of phosphorus doping to improve the electrochemical performance of activated carbon was explored through the combination of pore structure, phosphorus-containing functional groups and hydrophilic characterization. The results showed that the activation of phytic acid promoted the adsorption capacity and specific surface area of activated carbon, forming a microporous/mesoporous composite structure. Phytic acid was used as a phosphorus source to achieve phosphorus doping of activated carbon, and the binding types were C—P and C—P?????O, C—P—O and C—O—P. The introduction of phosphorus-containing functional groups improved the hydrophilicity of activated carbon, and provided active sites for pseudocapacitance reactions, and thus improving electrochemical performance. Theoretical analysis of capacitance contribution indicated that diffusion behavior was not the main factor limiting its capacitance behavior, which was mainly affected by the electric double layer on the electrode surface and the pseudo-capacitance reaction. Under the optimum conditions, when the activation temperature was 900℃ and the impregnation ratio was 1.5, the iodine adsorption value, methylene blue adsorption value and specific capacitance of phosphorus-doped activated carbon were 1321mg/g, 255mg/g and 222F/g (current density was 1A/g), respectively. After 9000 cycles, its capacitance retention rate was still as high as 98.77%, showing that phosphorus doping had the potential as a supercapacitor.

    Double dynamic covalent bond crosslinked nano-cellulose conductive hydrogel for a flexible sensor
    QIU Yijuan, LIN Jiawei, QIN Jirui, WU Jiayin, LIN Fengcai, LU Beili, TANG Lirong, HUANG Biao
    2022, 41(8):  4406-4416.  doi:10.16085/j.issn.1000-6613.2021-2052
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    Self-healing conductive hydrogels have great potential applications in flexible wearable devices because of their good self-healing properties and electrical conductivity. A double dynamic cross-linked hydrogel network based on borate ester bond and imine bond was synthesized via cross-linking polyvinyl alcohol (PVA) and polyethylenimine (PEI) with 4-formylbenzoboric acid (Bn). Then, PPy@CNF (grafted polypyrrole (PPy) on the surface of CNF) was incorporated to construct PBP-PPy@CNF nanocomposite hydrogels with good self-healing and electrical conductivity. The results indicated that when the content of PPy@CNF was 0.8wt%, the mechanical properties of the hydrogel were the best. The maximum stress and the fracture tensile strain can be up to 6.65kPa and 2080%, respectively with electrical conductivity of 2174μS/m. In the strain range of 0—800%,the gauge factor GF can be divided into three linear response regions,namely 0—200% (GF1=2.82), 200%—600% (GF2=7.15) and 600%—800% (GF3=12.85). The strain sensors integrated by PBP-PPy@CNF hydrogel with good stability and repeatability can efficiently identify and monitor the various human motions,showing promising applications in the field of wearable sensing devices. This study provided a new way for the design of conductive hydrogel and broadens the application of nanocellulose in sensor field.

    Effect of hydrothermal oxidation pretreatment on the physicochemical properties of fuel pellets prepared from cotton stalks
    YANG Jifan, ZHANG Shouyu, CAO Zhongyao, LANG Sen, LIU Simeng, ZHOU Yi, HU Nan, WU Yuxin
    2022, 41(8):  4417-4424.  doi:10.16085/j.issn.1000-6613.2021-1935
    Abstract ( 35 )   HTML ( 1)   PDF (1373KB) ( 15 )  
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    Cotton stalk (CS) was first pretreated by hydrothermal oxidation (HTO) process in an autoclave at 180—280℃ and then densified to prepare fuel pellets. The effect of HTO temperature on the physicochemical properties of the resulted CS pellets was investigated by thermogravimetric analyzer, X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FTIR), etc. The results indicated that the resulted CS yield decreased with the increase of HTO temperature. The hemicellulose contained in CS decomposes completely before HTO temperature reached to 180℃, the amorphous cellulose decomposed before 200℃, the crystalline cellulose decomposed before 260℃, and the relative content of the lignin gradually increased. The cellulose crystallinity of the resulted CS showed a decreasing trend as HTO temperature increases. The fixed carbon yield, the calorific value and the energy density of the resulted CS pellet increased, but the combustion characteristic became worse. The apparent density of the resulted CS pellet remained around 1300kg/m3, and the compressive strength decreased with increasing HTO temperature. The compressive strength of the pellet prepared from CS pretreated at 180℃ was the maximum, which increased by 183.33% compared with that from the raw material. The key factors affecting the compressive strength were crystalline cellulose which could act as a skeleton support and pseudo-lignin which acted as binder. The fuel pellet from CS pretreated at 180℃ showed the best combustion characteristic and physical properties with the calorific value of 17.76MJ/kg, the energy density of 23.44GJ/m3, and the compressive strength of 11.9MPa. The resulted indicated that the biomass pellets could be used as high-quality solid fuels.

    Performance of thermochemical sorption heat storage using manganese chloride/ammonia
    WANG Zhen, YAN Ting, HUO Yingjie
    2022, 41(8):  4425-4431.  doi:10.16085/j.issn.1000-6613.2021-2164
    Abstract ( 36 )   HTML ( 1)   PDF (1468KB) ( 21 )  
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    Thermochemical sorption heat storage has attracted extensive attention in recent years because of its advantages such as low heat storage loss, high heat storage density and cold and hot composite storage. An experimental test system of thermochemical sorption heat storage was established based on the thermochemical sorption technology. For direct thermal energy storage and release mode of thermochemical sorption heat storage, theoretical analysis and experimental research were conducted by employing the MnCl2/NH3 as the working pair. The results showed that the highest thermochemical sorption heat storage density was 1296.36kJ/kg MnCl2 or 1101.90kJ/kg consolidated composite sorbent under the charging temperature of 162℃, discharging temperature of 45℃ and condensation/evaporation of 25℃. The thermochemical sorption heat storage efficiency decreased from 38.98% to 24.08% when the discharging temperature increased from 45℃ to 85℃. Due to the influence of heat and mass transfer, chemical reaction kinetics and other factors, the actual heat storage performance of the sorption heat storage system under the same operating conditions was lower than the theoretical value. Thermochemical sorption heat storage was a very promising way for thermal energy storage, which could be used in the efficient recovery and utilization of medium and low temperature thermal energy, such as solar energy and industrial surplus/waste heat. This work could provide the strong technical support and had the important guiding significance for practical industrial application.

    Preparation and properties of polyurea/polyurethane shell microencapsulated essence by interfacial polymerization
    WANG Qiaoyi, LU Shaofeng, SHI Wenzhao, HONG Xun, YAO Dongxia, ZHANG Ling
    2022, 41(8):  4432-4440.  doi:10.16085/j.issn.1000-6613.2022-0202
    Abstract ( 26 )   HTML ( 0)   PDF (2001KB) ( 26 )  
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    Flavor microcapsules with three different structural shells of polyurea, polyurethane and polyurea/polyurethane were prepared by interfacial polymerization using jasmine flavor as the core material and isoflurone diisocyanate (IPDI) with diethylenetriamine (DETA), β-cyclodextrin (β-CD) and β-CD/DETA reactants as the wall material, respectively. The effects of different microcapsules shells on the microcapsules’ apparent morphology, thermal stability and flavor microcapsules’ slow release were investigated, and the flavor diffusion mode was analyzed by kinetic model. The results showed that the polyurea/polyurethane composite shell microcapsules prepared with β-CD/DETA had excellent capsule formation, dense and complete shells, the best thermal stability and slow release performance, and the textiles finished by them could maintain a strong fragrance for more than 90 days. The data of high-temperature slow release of the three flavor microcapsules at 100℃ and 120℃ were in accordance with the zero-level, first-level, Ritger-Peppas and Higuchi kinetic models. The Ritger-Peppas equation fitted to the polyurea/polyurethane composite shell had an n-value closer to 0.45, which was more consistent with Fick diffusion and better retarding performance.

    Fabrication and thermal properties of decanoic acid-paraffin/graphene aerogel form-stable phase change materials
    BAI Jingang, YUAN Zhengji, LIU Yu, ZHANG Yishi, LYU Xifeng
    2022, 41(8):  4441-4448.  doi:10.16085/j.issn.1000-6613.2021-2102
    Abstract ( 38 )   HTML ( 1)   PDF (2693KB) ( 25 )  
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    With the gradual advancement of the concept of carbon neutrality, adjusting energy supply policies and advocating low-carbon life can promote the green development of the whole society. The use of phase change materials (PCMs) to store and release heat can effectively use renewable energy and reduce the issue of CO2 emissions caused by fossil fuels. In this paper, graphene aerogel is used as the carrier of phase change materials, and a series of graphene phase change materials with high coating rate and low leakage rate are prepared by using different ratios of decanoic acid/paraffin for organic phase coupling. The study finds that when the decanoic acid/paraffin wax ratio of the graphene aerogel shaped phase change material is 7∶3, the phase change enthalpy reaches 202.91J/g. After 200 cycles, the phase change latent heat change of the composite material is within 4.25%, and the leakage rate is only 3.20%. The use of DSC, TG, XRD, SEM to analyze the microstructure of the material shows that graphene aerogel improves the shape stability of the phase change medium, effectively prevents the coupled organic phase during the phase change process from leaking, and enables the material to store and release heat stably, enhances the thermal conductivity, and has good application prospects.

    Biochemical and pharmaceutical engineering
    Differential effect of DDMZ1 cometabolic decolorization on the degradation of dyes with different structures
    FAN Jiao, XIE Xuehui, QIN Yan, CHEN Xiaoguang, FANG Yingrong, YANG Shanshan, ZHAO Jianggui, MO Haonan, ZHENG Hangmi, LIU Na, ZHANG Qingyun, SONG Xinshan
    2022, 41(8):  4449-4463.  doi:10.16085/j.issn.1000-6613.2021-2070
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    In order to explore the difference of decolorization efficiency and microbiological mechanism of functional flora DDMZ1 on five different dyes under the same co-matrix condition, the decolorization rate of functional bacteria DDMZ1 on 12 different dyes with five distinct structures was measured under the co-matrix condition of Yeast Extract (YE). Then, the degradation products of five typical dyes with different structures in YE co-matrix system were further identified by liquid chromatography/time-of-flight/mass spectrometry (LC-TOF-MS), and their degradation pathways were deduced. Finally, Illumina Miseq sequencing was utilized to evaluate the distinction in microbial community structure and the enrichment of dominant functional bacteria in YE co-substrate caused by five typical dyes with different structures, and further revealed the interactions between dye structures, community structures, dominant bacteria, and decolorization performances of dyes in YE co-metabolism substrate. The decolorization results indicated that, the addition of YE co-matrix could promote the decolorization efficiency of bacterial community significantly. After 72h treatment with 12 different structures of dyes at the concentration of 100mg/L, the decolorization rate of azo dyes could reach more than 80%, and the decolorization rate of triphenylmethane dyes, especially malachite green,increased from almost 0 to 98.3%. The decolorization rate of anthraquinone dyes also increased by about 20%. LC-TOF-MS analysis showed that the five typical dyes with different structures were biodegraded into metabolites with small molecular weight and simple structures under the action of YE co-substrate. The findings of high-throughput sequencing manifested that the addition of co-matrix YE notably increased the diversity of bacterial community structures in different dye samples compared with the mineral nutrients (MN) medium. Under the same co-matrix condition of YE, the dominant functional bacteria of dye samples with different structures were obviously different from each other. For example, the dominant functional bacteria in azo dye samples YEAO7, YERB5 and YECBE were Escherichia-shigella (accounting for 32.33%, 38.41% and 33.96%, respectively), Stenotrophomonas (47.40%) was dominant functional bacteria in anthraquinone dye samples YERBBR, and Pseudomonas (92.79%) was the absolute dominant functional bacterium in the samples of YEMG. These results indicated that dyes with similar structures might enrich semblable dominant functional bacteria genus, while dyes with different structures obviously enriched different dominant functional bacteria genus.

    Protoplast fusion preparation of three-effect engineered bacteria HL and its mechanism of algae dissolution
    HUANG Jinjie, MAO Linqiang, ZHANG Wenyi
    2022, 41(8):  4464-4472.  doi:10.16085/j.issn.1000-6613.2021-2167
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    In order to fundamentally control cyanobacteria, five strains of fusion bacteria were obtained by fusing protoplasm of the highly-efficiency Algicidal bacteria R1 and the denitrification and phosphorus accumulation bacterium B8 screened by research group. Taking Microcystis aeruginosa, the dominant algae species of cyanobacteria, as the test object, one of the strains (named HL) was optimized by the algae dissolution, nitrogen and phosphorus removal, and the kinetic model of degradation of Microcystis aeruginosa was constructed by using the substrate inhibition Haldane model. The algicidal effect was determined by treating the bacterial solution in different ways, and the algicidal effect was observed by scanning electron microscopy (SEM), supplemented by three-dimensional fluorescence and infrared spectroscopy to explore the mechanism of algae dissolution. The experimental results show that strain HL has the efficient algicidal ability, stable denitrification and phosphorus removal, and the degradation process of different concentrations of Microcystis aeruginosa in the symbiotic environment is in accordance with the Haldane equation, with the maximum specific growth rate (μm) of 1.046d-1, half-saturation constant (Ks) of 896.92mg/m3 and inhibition constant (KI) of 1568.95mg/m3, which indicates that strain HL has good tolerance and degradation ability to Microcystis aeruginosa and damages algae cells wall by secreting active substances such as aromatic amino acids, leading to the fragmentation and death of algae cells.

    Fine chemicals
    Synthesis and performance of silicon modified BPA-PA phenolic epoxy resin conductive adhesive
    GUO Rui, LI Ping’an, ZHAO Yunfei
    2022, 41(8):  4473-4480.  doi:10.16085/j.issn.1000-6613.2021-1945
    Abstract ( 34 )   HTML ( 1)   PDF (2302KB) ( 252 )  
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    Using bisphenol A paraformaldehyde phenolic resin (BPA-PA phenolic resin), dimethyldimethoxysilane and epichlorohydrin as raw materials, silicon-modified BPA-PA phenolic epoxy resin was obtained through transesterification and nucleophilic substitution reactions. FTIR and XPS were used for structural confirmation. Combining non-isothermal DSC, T-β extrapolation line and FTIR analysis, the optimal curing process conditions were studied. The effects of different silane addition levels on the properties of silicon-modified BPA-PA phenolic epoxy resin were discussed. Finally, silicon-modified BPA-PA phenolic epoxy resin was used as the matrix resin, and conductive fillers and additives were added to prepare a medium-temperature conductive adhesive. Conduct tensile shear strength, volume resistivity and thermogravimetric test analysis of its conductive adhesive were tested and analyzed. The results showed that the self-made silicon modified BPA-PA phenolic epoxy resin conductive adhesive had a tensile shear strength of 20.18MPa, a volume resistivity of 7.44×10-4Ω·cm and a residual carbon content of 68.89%. Compared with the conductive adhesive made of commercially available E-51 epoxy resin, the self-made silicon-modified BPA-PA phenolic epoxy resin conductive adhesive increased tensile shear strength by 5.73MPa and reduced volume resistivity by 3.86×10-4Ω·cm with increasing amount of residual carbon by 7.49%.

    Preparation and properties of silanylated polysuccinimide-loaded avermectin
    SU Shaochun, LIN Chengwei, ZHOU Xinhua, ZHOU Hongjun
    2022, 41(8):  4481-4490.  doi:10.16085/j.issn.1000-6613.2021-2084
    Abstract ( 29 )   HTML ( 2)   PDF (3796KB) ( 172 )  
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    In order to reduce the loss and degradation of pesticides, the nanomaterial and nanotechnologies have great potential to develop new nanoformulation. Silanylated polysuccinimide (PDSi) was prepared by the amine bond ring-opening reaction with 3-aminopropyl triethoxysilane and diaminobutane as functional monomers, which encapsulated avermectim (AVM) via self-assembly to form AVM@PDSi nanoparticles system. Compared with bare AVM, the leaves adhesion of AVM@PDSi is significantly improved with its leaf retention increased by 56.50%. Moreover, PDSi has good antioxidant activity with the maximum scavenging rate of 1,1-diphenyl-2-picrylhydrazide (DPPH) free radical being up to 41.88%. Under the same UV irradiation (Emax=365nm), the half-life of AVM (AVM@PDSi) is nearly half longer than bare AVM. Also, AVM@PDSi can intelligently control pesticide release by adjusting monomer ratio and pH, with the releasing rate for AVM@PDSi-3 being 67% after 72h and the fastest releasing at pH 9. More importantly, AVM@PDSi shows the good storage stability and retains the toxicity for insecticidal effect.

    Preparation and biodegradability of polyaspartic acid hydrogel
    YUE Yao, PU Mengfan, WANG Wenrui, ZHAO Jianbo, CAO Hui
    2022, 41(8):  4491-4497.  doi:10.16085/j.issn.1000-6613.2021-2049
    Abstract ( 32 )   HTML ( 2)   PDF (2354KB) ( 13 )  
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    Polyaspartic acid (PASP) gel was prepared with glycerol triglycidyl ether as the cross-linking agent. The thermal properties and viscoelasticity of this hydrogel were investigated, and the biodegradability was investigated by plate culture and zymotic fluid culture. Results showed that the glycerol triglycidyl ether crosslinked hydrogel had better heat resistance and viscoelasticity. The plate test proved that PASP hydrogel also had good biodegradability. The zymotic fluid culture proved that the type and dosage of crosslinking agent had great influence on the degradation of hydrogel. When the crosslinking agent was glycerol triglycidyl ether and the crosslinking degree was 60%, the degradation rate of gel on the ninth day was 49.3%, which was 9.2% lower than that of crosslinking agent of ethylene glycol diglycidyl ether, indicating that the network structure of glycerol triglycidyl ether was denser under the same crosslinking degree. When the cross-linking agent was glycerol triglycidyl ether and the crosslinking degree was 40%, the gel degradation rate was 59.8%, which was 17.5% higher than that when the cross-linking degree was 60%. This work laid a foundation for the practical application of polyaspartic acid hydrogel.

    Resources and environmental engineering
    Research status and progress of waste tire pyrolysis technology
    JI Xuanyu, LIN Weijian, ZHOU Xiong, BAI Jisong, YANG Yu, KONG Jie, LIAO Chongyang
    2022, 41(8):  4498-4512.  doi:10.16085/j.issn.1000-6613.2021-2045
    Abstract ( 57 )   HTML ( 0)   PDF (1541KB) ( 850 )  
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    According to the current research of waste tire treatment, the pyrolysis mechanisms and technologies were analyzed and compared. The effects of process parameters such as pyrolysis temperature, heating rate, material particle size and catalyst on the yield of pyrolysis products were discussed seriously. It indicated that the kinetic model proposed by the Coast-Redfern integration method was more accurate relatively, and the average reaction activation energy was about 129.5kJ/mol. The current research indicated that the pyrolysis temperature had the greatest influence on the products yield, and the yield of gas and liquid products increased with increasing temperature. Relative higher yield of liquid products and higher quality of solid products were able to be achieved in the pyrolysis temperature ranges of 500—550℃ and 500—650℃, respectively. Furthermore, the characteristics and applications of the solid, liquid and gas three-phase products were analyzed and summarized, as well as the distributions and control methods of pollutants (S, PAHs), to provide a technical basis for the industrial development of waste tire pyrolysis technology. The technology references for the industrial application of waste tire pyrolysis were concluded consequently.

    Treatment of antibiotic wastewater enhanced by zero-valent iron and its coupling technology
    ZHU Tingting, SU Zhongxian, ZHAO Tianhang, LIU Yiwen
    2022, 41(8):  4513-4529.  doi:10.16085/j.issn.1000-6613.2021-2026
    Abstract ( 58 )   HTML ( 2)   PDF (3279KB) ( 38 )  
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    Antibiotics are widely used in the treatment of diseases, animal husbandry and pest control, etc. However, the large-scale production and use of antibiotics have caused lasting damage to the ecosystem. And incompletely degraded antibiotics gradually accumulated in the environment, leading to the enrichment of antibiotic resistance genes (ARGs), which will also pose a great threat to our environment. Therefore, it's urgent to develop antibiotic treatment methods that are cost-effective and can reduce ARGs. Zero-valent iron (ZVI) has been widely used in treating wastewater containing refractory pollutants due to its advantages of low cost, easy operation and without secondary pollution. It has also been widely studied in the treatment of antibiotic wastewater. In present paper, the application of ZVI and its coupling technology in the treatment of antibiotic wastewater from the aspects of the action mechanism of ZVI and its coupling technology on antibiotics and the effect of ZVI on anaerobic digestion were summarized. The ZVI degrades antibiotics mainly by generating hydroxyl radical (·OH). In addition, hydroxides and oxides formed from ZVI can adsorb and remove a large number of antibiotics. The ZVI coupled photo-Fenton or electro-Fenton could promote the generation of ·OH through light or electric energy, and realize the recycling of Fe2+. In the process of ZVI coupled anaerobic digestion, ZVI could promote the degradation of antibiotics and reduce some ARGs by optimizing microbial community and improving enzyme activity. In view of the characteristics of the above process, synthesizing cost-effective ZVI materials, and exploring the reduction mechanism of ARGs by ZVI in anaerobic digestion will be the focus of future researches.

    Review on selective recovery of lithium from cathode materials in spent lithium-ion batteries
    WANG Yue, ZHENG Xiaohong, TAO Tianyi, LIU Xiuqing, LI Li, SUN Zhi
    2022, 41(8):  4530-4543.  doi:10.16085/j.issn.1000-6613.2021-1940
    Abstract ( 84 )   HTML ( 13)   PDF (1878KB) ( 81 )  
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    With the vigorous development of the energy vehicle market, lithium-ion battery, as the key component of the new energy vehicles, has been facing the risk with insufficient supply of critical metal resources especially lithium resource. Recycling secondary lithium resources contained in waste lithium-ion batteries will become an indispensable way to solve the problem of unbalanced supply and demand of lithium resources and promote the sustainable development of the industry. Therefore, selective extraction of lithium by step or priority, which could promote efficient extraction of lithium from spent lithium-ion batteries, has attracted much attention of researchers. This review introduces four current mainstream methods of selective extraction including pyrometallurgy, hydrometallurgy, mechanochemical method and electrochemical method. And based on explaining their basic reaction mechanism, the results of the latest researches are summarized separately and the advantages and disadvantages of each extraction method are deeply analyzed from the several quantitative indexes such as energy consumption, material consumption, recovery ratio, selectivity and environmental impact. Finally, the development trend and prospect of the recovery of valuable metals in spent lithium-ion batteries are put forward, aiming at providing references for the development of cleaner and more efficient recycling process in the future.

    Research progress on enhancing resource utilization of organic solid waste aerobic composting based on biochar
    HUANG Xia, HE Yingying, ZHANG Yidie, YANG Dianhai, DAI Xiaohu, XIE Li
    2022, 41(8):  4544-4554.  doi:10.16085/j.issn.1000-6613.2021-2129
    Abstract ( 59 )   HTML ( 2)   PDF (1304KB) ( 35 )  
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    Aerobic composting is an effective means of rendering organic solid waste harmless, stable and resourceful. In recent years, biochar has shown great promise as a compost conditioner to optimize composting environmental parameters, accelerate the composting process and improve compost quality. Biochar has a rich porous structure and huge specific surface area, strong water holding capacity, cation exchange capacity and adsorption capacity. These properties have great advantages in promoting the composting process, such as promoting the degradation of organic matter and the formation of humus, strengthening the activity of microbial communities, reducing odor and greenhouse gas emissions, and reducing the biological effectiveness of heavy metals, antibiotics, and other pollutions. This paper reviews the role of biochar in the aerobic composting process of different types of organic wastes, summarizes the application of biochar-based enhancements in composting, and proposes future research directions for biochar, aiming to optimize the aerobic composting process in terms of functional materials and provide theoretical basis and data support for the application of biochar in aerobic composting.

    Study of CO2 absorption stability of AEP-DPA-CuO phase change nanofluids
    LU Shijian, LIU Ling, LIU Ziwu, GUO Bowen, YU Xulin, LIANG Yan, ZHAO Dongya, ZHU Quanmin
    2022, 41(8):  4555-4561.  doi:10.16085/j.issn.1000-6613.2021-0195
    Abstract ( 41 )   HTML ( 1)   PDF (1205KB) ( 17 )  
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    The core of CO2 capture technology by chemical absorption method is absorbent, and the stability of absorbent is the key to realize the long-term continuous operation of CO2 capture device. The degradation of 0.6mol/L AEP-0.4mol/L DPA-0.1mol/L ACT phase change organic amine absorption system under high temperature and oxygen-containing conditions leads to the technical problems of corrosion enhancement and absorbent loss. The degradation components were analyzed and the main influencing factors were studied. It was found that CO2 loading, O2 and temperature had great influence on the degradation rate, and the order of influencing factors was: CO2>O2>temperature. Fe3+ had greater influence on oxidative degradation than on thermal degradation. By GC-MS analysis, there were three kinds of thermally stable salts in thermal degradation and six kinds of thermally stable salts in oxidative degradation. To inhibit thermal degradation and oxidative degradation, six kinds of antioxidants, such as potassium sodium tartrate, were selected for investigation. The results showed that the best antioxidant was acetone oxime, and the best dosage was 800mg/L, in which the thermal degradation inhibition rate was 97.9%, and the oxidative degradation inhibition rate was 98.3%. The low degradation rate of AEP-DPA-ACT phase change system was realized, which provided a guarantee for the stable operation of phase change nanofluids.

    Oxidative degradation of naproxen in water by UV-Fe(Ⅵ) process
    YI Xuenong, LI Jingmei, GAO Yuqiong
    2022, 41(8):  4562-4570.  doi:10.16085/j.issn.1000-6613.2022-0121
    Abstract ( 27 )   HTML ( 1)   PDF (2132KB) ( 17 )  
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    The degradation rate of naproxen (NPX) can be significantly improved by activating ferrate under UV light. The effects of different process, Fe(Ⅵ) concentration, pH, phosphate, HCO3-, Cl- and humic acid (HA) were investigated. The main active species of the reaction were determined by the free radical quenching experiment and the intermediate valence iron identification experiment. In addition, the mineralization degree of NPX was determined by TOC and the possible degradation paths were proposed on the basis of the intermediates detected by liquid chromatography-mass spectrometry analysis. The results showed that after 60min of reaction, Fe(Ⅵ) alone can hardly degrade NPX. The degradation rate of NPX by UV alone was less than 26%, while the degradation rate of NPX by UV-Fe(Ⅵ) process was as high as 82%. The degradation process conformed to the pseudo-first-order kinetic law (R2>0.95) with a reaction rate constant of 0.0306min-1, which was 6.2 times and 102 times of the degradation rates of UV alone and Fe(Ⅵ) alone, respectively. The initial pH of the solution had a significant effect on the degradation of NPX in the UV-Fe(Ⅵ) process, and the degradation was favored under acidic conditions, mainly due to the dual effect of different forms of ferrate and NPX at different pH. At the same pH, phosphate had a significant inhibitory effect on the degradation of NPX, mainly because of the complexation of phosphate and the decomposition products of ferrate resulting in a decrease in ·O2-. In addition, Cl- and HA had different degrees of inhibition on NPX degradation. However, HCO3- had a promoting effect on degradation, because the addition of HCO3- increased the pH of the solution and enhanced the stability of ferrate. The dominant active species in the UV-Fe(Ⅵ) process is ·O2-, which decarboxylates NPX mainly through electron transfer mechanism and finally generates acids, ketones and ethers.

    Synthesis of polymeric ionic liquid and its performance on adsorption desulfurization
    SHAN Qingwen, ZHANG Juan, WANG Yajuan, LIU Wenqiang
    2022, 41(8):  4571-4579.  doi:10.16085/j.issn.1000-6613.2021-1963
    Abstract ( 57 )   HTML ( 3)   PDF (1997KB) ( 26 )  
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    Functionalized ionic liquid monomer was synthesized from N-methyldiallylamine and metal phthalocyanine, and then polymerized on the surface of the carrier(silica gel ball) to prepare a polymeric functionalized ionic liquid as an adsorbent[(NMDA-Pc/Ni2+)/SiO2]. The adsorbent was characterized by infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, and polarized light microscope. The adsorption and desulfurization performance of the adsorbent for dibenzothiophene(DBT) at normal pressure and room temperature was investigated. The optimal adsorption conditions were the amount of adsorbent of 1.5g/10mL model oil, and the adsorption time of 20min, under which the maximum adsorption capacity of DBT was 6.198mg/g. The adsorption behavior of the adsorbent to DBT followed the Freundlich adsorption isotherm model and the pseudo-second-order kinetic model. The adsorbent was washed and regenerated with methanol, and the adsorption performance was not significantly reduced after reused for 5 times. Both olefins and aromatics affected the adsorption desulfurization performance of the adsorbent, with the former being more significant. The adsorbent also had a good adsorption for different sulfur compounds, and the removal order was dibenzothiophene>benzothiophene>thiophene.

    Effect of exopolysaccharide content on alkaline-thermal hydrolysis process of dissolved sludge protein and hydrolysate solid-liquid separation performance
    XIE Li, LI Xiufen
    2022, 41(8):  4580-4586.  doi:10.16085/j.issn.1000-6613.2021-2046
    Abstract ( 39 )   HTML ( 4)   PDF (3420KB) ( 20 )  
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    In recent years, with the emergence of resource shortages and environmental pollution, the research on the recovery and utilization of surplus sludge protein has received extensive attention. This paper focused on the study of the influence of the content of extracellular polysaccharides on the dissolved sludge protein and the hydrolysate solid-liquid separation by the alkaline-thermal hydrolysis method, and the preliminary analysis of its influence mechanism was carried out. The results showed that the increase in the content of extracellular polysaccharides had a significant inhibitory effect on the protein dissolution of the remaining sludge, and at the same time, the solid-liquid separation performance of the hydrolysate deteriorated. When the mass fraction of extracellular polysaccharide was 350mg/gTS, the dissolution rate of protein was 29.62%, the mass fraction of DNA in the hydrolysis residue was 233.33mg/gTS, the volume of the filtrate was 23.60mL, and the viscosity of the hydrolysate was 545.33mPa·s. Excitation emission matrix spectra and confocal laser scanning microscopy showed that with the increase of extracellular polysaccharide content, the Maillard reaction between polysaccharide and protein intensifies, and the area coverage of polysaccharide increased, which were not conducive to the dissolution of sludge protein.

    Perspective
    Exploration of the development path for the hydrogen energy
    ZHOU Ying, ZHOU Hongjun, XU Chunming
    2022, 41(8):  4587-4592.  doi:10.16085/j.issn.1000-6613.2022-0396
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    Hydrogen has three characteristic uses: chemical, exclusive fuel and secondary energy. During the proposed energy revolution, the government will promote the development of photovoltaic wind power to achieve CO2 emission reduction. With the reduction of photovoltaic wind power costs, green hydrogen has shifted from chemical to exclusive fuel and secondary energy properties. In the meantime, China’s 30·60 goal is to lead re-electrification, which will change the steel, refining, coal chemical, oil-gas fields, automobiles, coal power and cement industries. Western China will realize hydrogen energy transformation through photovoltaic in-situ electrolysis of water and green gas islands. Green hydrogen produced in eastern China may become a carrier tool for rural revitalization and an important starting point for the creation of low-carbon cities. Advanced layout, strengthening innovation, continuous breakthroughs in the key core technologies of hydrogen energy and long-term adherence to technological iteration and industrial demonstration are the fundamental ways to realize the industrialization of hydrogen energy.