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Table of Content
01 August 2020, Volume 39 Issue 8
    Chemical processes and equipment
    Interconnected chemical engineering: an intelligent manufacture mode of chemical industry emphasizing the integration of multiscale
    Xu JI, Yagu DANG, Li ZHOU, Yiyang DAI
    2020, 39(8):  2927-2937.  doi:10.16085/j.issn.1000-6613.2019-1835
    Abstract ( 529 )   HTML ( 30)   PDF (4729KB) ( 413 )  
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    The manufacture of chemical products is realized through the controlled conversion and transfer of mass and energy in chemical processes with diversity features, such as polyphasic, nonlinear, non-equilibrium, multi-scale and multi-spatial etc. The key of the development of intelligent manufacturing in the chemical industry is to achieve the interconnection between the involved subsystems and high process efficiency under multi-scale conditions. On the one hand, the understanding and regulation of the multi-scale interconnection mechanism of chemical processes is crucial for the safe and reliable operation of chemical systems. On the other hand, the realization of the interconnection, integration and collaboration between the subsystems at multiple scales in the chemical processes is the way for the green development of the chemical industry. Therefore, this work proposed an intelligent manufacturing mode for multi-scale integration in the chemical industry, which was identified as interconnected chemical engineering. In this paper, the concept, objectives, features and technical framework of interconnected chemical engineering were provided. The key technologies of interconnected chemical engineering were discussed. They included multi-level cyber-physical systems in the chemical industry, cloud manufacturing, the secure technologies of product lifecycle management, the model of dynamic safety monitoring and decision-making under the coupling and interlocking mechanism, and blockchain-based security technology with interconnected chemical data.

    Research progress on optimization of freezing stage in enhancement of freeze-drying
    Shuo ZHANG, Wei WANG, Yizhe LI, Yujia TANG, Nan LIU
    2020, 39(8):  2937-2946.  doi:10.16085/j.issn.1000-6613.2019-1713
    Abstract ( 380 )   HTML ( 19)   PDF (2929KB) ( 221 )  
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    Freeze-drying is characterized by high quality product but long drying time and high energy consumption. Optimization of freezing stage in freeze-drying was reviewed in the present article from the viewpoint of process enhancement. Conventional optimization methods of freezing stage comprise freezing rate control, ice nucleation regulation and annealing, which can all attain large and uniform ice crystals. A common feature of these methods is that the sublimation drying rate can be increased due to the increased size of crystals, while the desorption drying rate would be decreased due to the decreased internal surface area. These conventional optimization methods can moderately improve the drying rate of less hygroscopic materials. Due to its higher vapor pressure, organic solvent as a cosolvent can increase the driving force of mass transfer. However, the requirement for a lower residual content of organic solvent restricts its wide application compared with pure water in food, pharmaceutical, and biological industries. The technical idea of “freeze-drying of initial unsaturated porous media” provides a new solution for optimization of freezing stage. The key point of the proposal is that liquid material to be dried is first prepared into frozen material with a certain initial porosity, and then freeze-dried. The prefabricated pore structure benefits the migration of sublimated vapor and the tenuous solid substrate promotes the desorption of bound moisture. This kind of frozen material can simultaneously enhance the sublimation drying stage and desorption drying stage. This novel method is a perfect combination of high product quality with low processing cost, and is able to solve the problem of long drying time and high energy consumption in the traditional freeze-drying process.

    Analysis of the factors affecting the conveyance of catalyst in the regenerated standpipe of FCCU
    Wei PENG, Yansheng LIU, Shengxian HAN, Bingqing HUANG
    2020, 39(8):  2947-2953.  doi:10.16085/j.issn.1000-6613.2019-1486
    Abstract ( 270 )   HTML ( 10)   PDF (1634KB) ( 149 )  
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    The regenerated standpipe is used for conveying the regenerated catalyst between the regenerator and the riser in FCC unit. The flow patterns of catalyst in standpipe are influenced by many factors which complicates the operation. The influence factors of conveying catalyst in standpipe were investigated by measuring the axial pressure distribution inside the standpipe at different operating conditions on a 1.0Mt/a FCC unit. The operation result showed that the main factors affecting the standpipe operation included the density and average particle size of the catalyst, structure of standpipe, the position of slide valve, the properties and flow rate of the aeration gas, et al. Low density catalyst and high viscosity aeration gas can reduce bubble size and maintain stable reaction temperature. Aeration gas rate should be adjusted in time according to the standpipe driving force and slide valve pressure drop to avoid packed bed flow. In addition, standpipe structure and the position of the slide valve had great influence on the standpipe driving force. The analysis made in this work can be used as reference for the standpipe design and the revampment of FCC unit.

    Study on methane hydrate formation and decomposition characteristics in gas-water system
    Ting HUANG, Changjun LI, Ling DING, Qingping LI, M Aman ZACHARY
    2020, 39(8):  2954-2961.  doi:10.16085/j.issn.1000-6613.2019-1641
    Abstract ( 317 )   HTML ( 10)   PDF (1767KB) ( 152 )  
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    In order to further find out the effect of stirring on the methane hydrate formation and decomposition characteristics, a series of methane hydrate kinetically experiments under different stirring conditions was conducted by means of a transparent high-pressure autoclave. This autoclave had a volume of 522mL with the highest operating pressure of 21MPa. Several aspects were obtained including the function of stirring on the amount of total hydrate volume, the hydrate growth and decomposition rate, as well as the hydrate slurry flow property under different stirring rate based on the measured motor torque. The type of the stirring motor was ViscoPakt Rheo-57 which had the function of measuring stirring torque. The range of acceptable torque was 0~57N·cm with an accuracy of ±0.04N·cm. The experimental results indicated mainly three pieces of information. Firstly, the maximum amount of hydrate volume, the biggest and the stable hydrate growth rates increased with increasing stirring rate during the hydrate fast growth period. It was further verified that mass transfer was the primary factor controlling the hydrate formation process. Secondly, in the hydrate decomposition period, stirring can improve the dispersivity of hydrate particles and promote the transport of decomposition gas. Lastly, the motor torque of hydrate slurry presented a first stable and then increasing and final drastic fluctuation feature along with the increase of stirring rate. As a result, the critical volume fraction of solid hydrate particles that the hydrate slurry can carry was defined. The conclusions of this study can uncover the mechanisms of hydrate formation and decomposition to some degree and also provide a reference for the research of kinetic prediction models.

    Structural optimization of dividing wall column using response surface methodology coupled with NSGA-Ⅱ algorithm
    Jiangwei XIE, Chunli LI, Guoming HUANG
    2020, 39(8):  2962-2971.  doi:10.16085/j.issn.1000-6613.2019-1716
    Abstract ( 303 )   HTML ( 6)   PDF (4287KB) ( 175 )  
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    The optimal design of the dividing wall column (DWC) involves multiple variables. The complex interactions among the variables are complicated. This not only increases the design difficulty of the DWC but also limits its potential for industrial applications. In order to solve this problem, a multi-objective optimization using the response surface methodology (RSM) coupled non-dominated sorting genetic algorithm (NSGA-Ⅱ) was proposed for DWC design and optimization. Firstly, the design variables were determined and their levels were determined by using single-factor analysis. The experimental design were carried out by the BBD (Box-Behnken) method, and the objective functions of total annual cost (TAC) and reboiler duty (Q) were calculated by numerical simulation. Secondly, the statistical significance of each regression model was then evaluated by analysis of variance (ANOVA) and expressed as a quadratic polynomial. Finally, the response surface models were optimized by NSGA-Ⅱ algorithm, and a series of optimization schemes was obtained by calculating the Pareto front. Compared with the traditional process, the research showed that the analysis and optimization of the DWC by this new method can effectively reduce the Q while reducing the TAC, and provide a new idea for the optimization design of the DWC.

    Dynamic process and optimization for separation of 1,4-butanediol dehydration products using batch distillation method
    Rongli MI, Zijian FENG, Chunhai YI, Bolun YANG
    2020, 39(8):  2972-2979.  doi:10.16085/j.issn.1000-6613.2019-1744
    Abstract ( 388 )   HTML ( 9)   PDF (1321KB) ( 210 )  
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    To efficiently separate 3-buten-1-ol from dehydration products of 1,4-butanediol, a batch distillation process was designed in this work. The dehydration products in the batch distillation process were cut into three parts: light components, intermediate components and heavy components according to the composition and properties of the dehydration products. The batch distillation model was established based on the Aspen batch distillation module and the operating parameters were optimized by the uniform experimental design method. The comparison between the experimental and simulation results showed that the Aspen batch distillation module could simulate the batch distillation process of 1,4-butanediol dehydration products. The operating parameters including reflux ratio of light components and intermediate components, column kettle temperature, end condition of light component receiver and intermediate component receiver after optimization were 14.91, 17.00, 180℃, 73.81℃ and 117.69℃, respectively. Using the optimized operating parameters, the batch rectification process yielded 3-buten-1-ol with a purity of 95.1% and a single pass yield of 73.2%, which was 1.9% and 11.3% higher than before optimization. The research results provide a theoretical basis and data support for the industrial implementation of 1,4-dutanediol dehydration to 3-buten-1-ol.

    Investigation on characteristic of mass-flow in loop heat pipe with different working fluids under different load powers
    Chao LIU, Rongjian XIE, Deping DONG
    2020, 39(8):  2980-2988.  doi:10.16085/j.issn.1000-6613.2019-1776
    Abstract ( 282 )   HTML ( 7)   PDF (2621KB) ( 100 )  
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    The transient mass transfer of loop heat pipes (LHP) was studied to improve the simulation precision and enrich the experimental research methods for LHP. The mass flow rates of three LHPs with acetone, ethanol, and propylene as working fluids under different heating powers were investigated using a high-precision mass flowmeter. Results showed that at the start-up stage, when the heat load was 10W, the propylene LHP started up faster than that of the acetone and the temperature stability of two LHPs appeared lingeringly than the stability of mass flow; at steady state, with the increase of heat load, the average mass flow of LHP with different working fluids increased linearly, while the transient mass flow fluctuated continuously, and the fluctuation amplitudes decreased initially and then increased. The fluctuation amplitude of mass flow was jointly affected by the compressibility of vapor working medium and the heat applied on the capillary core. Through spectrum analysis, it was found that the fluctuation of liquid mass flow was also affected by the two-phase area of condenser. Under high heat loads, the heat load on the capillary core played a leading role, and the exacerbated fluctuation of vapor mass flow with large periodic variation was observed. The fluctuation frequency accelerated under a higher heat loads.

    Nucleate pool boiling heat transfer characteristics of perfluoroalkyl quaternary ammonium iodide
    Meibo XING, Zhiming GONG, Ruixiang WANG
    2020, 39(8):  2989-2997.  doi:10.16085/j.issn.1000-6613.2019-1778
    Abstract ( 290 )   HTML ( 9)   PDF (2189KB) ( 163 )  
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    Saturated pool boiling heat transfer experiments for different concentrations of perfluoroalkyl iodide (Le-134) aqueous solution has been experimentally investigated. The interface adsorption characteristics of Le-134 and the wettability of copper surface were investigated firstly. The static surface tension decreased with increasing concentration, and the variation of dynamic surface tension reduction increased with increasing concentration. At the concentration exceeding CMC (≥40mg/L), the surface tension of the solution was reduced to less than 20mN/m within 10s. Le-134 solution had good wettability, and the contact angle of the aqueous solution on the surface of the copper decreased with increasing concentration, which was only 21° at 300mg/L. Compared with deionized water, the amount of bubbles produced by Le-134 aqueous solution in pool boiling was significantly increased besides the bubble size and the bubble coalescence was reduced. It can be demonstrated that the heat transfer enhancement was more effective with the increase of concentration at the same heat flux, while the heat transfer performance was weakened with the increase of heat flux at the same concentration. Compared to deionized water, the obvious enhancement was observed at 10W/cm2 with 300mg/L Le-134. The superheat of the boiling surface was reduced by 49.3%, and the boiling heat transfer coefficient was increased by 109.1%.

    Development and verification of the transient capture model of slug flow based on the traveling wave method
    Dongxu WANG, Qihui HU, Yuxing LI, Shuang LI, Quan WANG
    2020, 39(8):  2998-3006.  doi:10.16085/j.issn.1000-6613.2019-1861
    Abstract ( 227 )   HTML ( 8)   PDF (2069KB) ( 278 )  
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    It is of great practical significance to accurately predict the characteristic parameters of slug flow in gas-liquid two-phase flow. The Renault model is a two-fluid model based on the non-viscous Kelvin-Helmholtz stability criterion and the viscous Kelvin-Helmholtz stability criterion, which can capture the interface movement of the slug front and rear. However, this model uses Riemann precise solution between liquid phase cells and the solution speed is slow. In order to simplify the calculation, the traveling wave method was introduced into the solution process of the liquid phase equation in the Renault model, and the possible dry areas were replaced with thin liquid film, making the traveling wave method applicable to all computing units. Under the condition of ensuring the accuracy of the model, the calculation speed was greatly improved, and the operation time was reduced by 28% on average compared with the Renault model. By comparing the calculation results of this model with the data of indoor small-scale loop experiment, the liquid holding rate is consistent with the measured results. The relative errors of pressure drop and slug length calculation are respectively within 25% and 30%, and the main distribution is within 20%. It shows that the improved transient slug flow model has the characteristics of fast calculation and high calculation accuracy, and has certain engineering application value.

    Liquid-liquid two-phase flow pattern and mass transfer in a rotating microchannel extractor
    Rui MA, Chunxin FAN, Jianhong LUO, Jun LI, Benhe ZHONG
    2020, 39(8):  3007-3013.  doi:10.16085/j.issn.1000-6613.2019-1748
    Abstract ( 290 )   HTML ( 7)   PDF (2355KB) ( 181 )  
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    The liquid-liquid two-phase flow pattern in rotating microchannel extractor (RME) was observed and recorded by high-speed photography. The extraction of chromium (Ⅲ) from water to an organic phase was selected as the experimental system. Three types and nine kinds of flow patterns were observed, namely, drop flow (sheet flow, drop sheet flow, drop banding flow), banding flow (banding flow, chaotic flow), and aqueous-organic flow (aqueous-organic drop flow, aqueous-organic banding flow, aqueous-organic banding annular flow, aqueous-organic filiform flow). Various factors, such as the size of the microchannel device, the rotating speed of the inner cylinder and the feeding velocity that could change the flow pattern were investigated. It was found that with the increase of flow velocity and rotation speed, the flow pattern in RME underwent drop flow to banding flow and then to aqueous-oil flow. Furthermore, the Weber number of aqueous phase and organic phase were correlated to form the flow pattern diagram, and the linear relationship between the inertial force and viscous force in RME was found. Finally, to find the flow pattern with high extraction efficiency, the extraction experiments of chromium were carried out under nine different flow patterns. This study of the flow pattern in the RME lays the foundation for the later experiments and the application of the device.

    Energy processes and technology
    Research progress on the deacidification technologies of crude oil and various distillates
    Bai HE, Xin LIAN, Songshan JIANG, Bo YU, Changguo CHEN, Lin CHEN, Dengli LEI, Mengqing GONG
    2020, 39(8):  3014-3026.  doi:10.16085/j.issn.1000-6613.2019-1709
    Abstract ( 320 )   HTML ( 20)   PDF (1390KB) ( 146 )  
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    Petroleum acid is a common corrosive substance in crude oil and its distillates, and the main component of the petroleum acid is naphthenic acid the content of which can be as high as 90%. Naphthanoic acid has all the chemical properties of carboxylic acid, so it often causes serious corrosions that affect the normal operations and service life of crude oil processing equipment and the devices that oil products contact with. With the increasing production of high acid value crude oil in the world in recent years, the corrosions and product quality problems caused by high acid value crude oil and the high acid value distillate are becoming more and more serious, so it is urgent to develop an economical and efficient deacidification technology to process the naphthenic acids. In this paper, various deacidification techniques for crude oil and oil products at home and abroad are reviewed and comprehensively summarized in detail. The analysis shows that there are many deacidification technologies reported at present, among which the hydrodeacidification effect in industrial application is good but the cost is high, while most of the other deacidification methods have many shortcomings. Therefore, it is very necessary to explore a green, environmentally friendly, efficient and universal oil deacidification process. Esterification deacidification process is simple and does not need complex subsequent treatment, and it can almost reduce the acid value of all high acid value crude oil and oil products (light and heavy distillate, residual oil), which will provide conveniences for the further processing of oils. The key point of esterification deacidification process is to develop high efficient catalysts. Although the current catalytic esterification system has a high deacidification rate, there is still a common deficiency of long reaction time. It is believed that after this problem is solved by strengthening the reaction process, the catalytic esterification deacidification process will soon be used to the actual industrial production of crude oil and oil products.

    Advances in the application of computer simulation technology in biomass conversion
    Pengkun GUO, Pan LI, Chun CHANG, Guizhuan XU, Xiaohua SHI, Jing BAI, Shuqi FANG
    2020, 39(8):  3027-3040.  doi:10.16085/j.issn.1000-6613.2019-1537
    Abstract ( 413 )   HTML ( 14)   PDF (3015KB) ( 344 )  
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    Biomass is a renewable energy source that is derived from animals and plants and has carbon fixation capabilities. This paper reviews the research progress of computer simulation in biomass conversion. Firstly, the main conversion and utilization technologies of biomass are introduced, which includes biomass gasification, liquefaction, physical conversion, bioconversion, etc. On the basis, the application progress of computer simulation assisting biomass conversion research is summarized, including process simulation based on thermodynamic model and kinetic model Aspen Plus and PRO/Ⅱ, and the molecular simulation based on quantum chemistry Gaussian 09w and Materials Studio, and the condition optimization simulation based on the analysis of the interaction of multiple parameters and the optimization Design Expert. Meanwhile, the application of life cycle assessment (LCA), neural network simulation (artificial neural networks, ANNs), and numerical simulation in biomass conversion are overviewed. Finally, the future development of computer simulation in biomass conversion is prospected. It is pointed out that it should continue to study the process which conforms biomass conversion, avoiding the model of simplifying the real process, and further enhance the reliability of simulation effect through the combination of different simulations.

    Research status and development trend of high-value utilization of crude glycerol
    Dongxiang WANG, Chen WANG, Shijie WANG, Guizhuan XU, Chun CHANG
    2020, 39(8):  3041-3048.  doi:10.16085/j.issn.1000-6613.2019-1634
    Abstract ( 358 )   HTML ( 10)   PDF (1227KB) ( 370 )  
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    Crude glycerol is the by-product of the biodiesel production, and its green treatment and application have become an urgent research topic. This paper introduces the research status of biological, chemical and electrochemical conversion methods of crude glycerol. On this basis, the research status of the production of 1,3-propanediol and hydrogen from crude glycerol by bioconversion, the production of acrolein and polyurethane by chemical conversion and the preparation of fuel cell by electrochemical conversion are reviewed, respectively. The research and development trend of high-value use of crude glycerol are also analyzed. Crude glycerol bioconversion has the disadvantages of the high cost of the culture medium and difficulty in product separation, which limits the current industrial application. Meanwhile, chemical conversion methods are still in the initial research stage, whereas electrochemical conversion methods have a good development space as emerging technologies. This paper points out that crude glycerol can be used as a new type of biomass resource, and the research of crude glycerol-based chemicals and new materials have broad prospects for development.

    Effect of quartz sand particle size on the formation and distribution of methane hydrate
    Yingmei WANG, Shiqiang DONG, Jing ZHAN, Qingbai WU, Peng ZHANG
    2020, 39(8):  3049-3056.  doi:10.16085/j.issn.1000-6613.2019-1788
    Abstract ( 264 )   HTML ( 3)   PDF (2714KB) ( 113 )  
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    In order to study the formation of methane hydrate in porous media with different particle sizes, quartz sand with particle sizes of 0.075—0.5mm, 0.5—1mm, 1—2mm and 2—3mm were used as porous media. The hydrate formation experiment was carried out at an initial pressure of 7.0MPa and a temperature of 0.5℃, and then the sampling observation and delamination were performed. Results showed that with the increase of medium particle size, the initial rate of formation and the amount of hydrate formation in the pores of quartz sand were decreased gradually, the hydrate began to form during aeration process in three particle sizes of 0.075—0.5mm, 1—2mm and 2—3mm, and there was a large amount of hydrate formation in particle size of 0.5—1mm during the hydrate formation process. The particle size of 0.5—1mm had the maximum gas consumption of 0.47mol, and gas consumption in particle size of 2—3mm was the minimum of only 0.05mol. According to the sampling observation, the methane hydrate on the surface of these four quartz sand bodies was mainly distributed evenly among the particles with dispersed or cemented into blocks. However, it was different from the result that the amount of hydrate in the upper part of sand body was more than that in the lower part of sand body by decomposition method. There was only a large amount of hydrate accumulation occurred on the top of quartz sand with 0.5—1mm. Therefore, it was inferred that when there was a large void in the upper part of a medium system with a certain particle size, the hydrate may be enriched in the void. The experimental result had certain reference value for the prediction of hydrate occurrence area and morphology in natural environment.

    Industrial catalysis
    Progress of alkylation catalysts for benzene with syngas
    Tengfei HAN, Hong XU, Hui GE, Xuekuan LI
    2020, 39(8):  3057-3065.  doi:10.16085/j.issn.1000-6613.2019-1681
    Abstract ( 334 )   HTML ( 13)   PDF (1433KB) ( 145 )  
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    Para-xylene (PX) is an important raw material for the preparation of polyester materials. With the rapid development of China’s economy, the demand for PX is growing rapidly. It is now mainly produced through petrochemical route. However, China lacks petroleum and urgently needs to develop coal-based PX production technology. The preparation of PX by alkylation of benzene with syngas is a new route, which has attracted much attention in recent years. In this paper, the recent research progress of alkylation of benzene and synthesis gas is reviewed in detail. The effects of the combination of noble metal (Pt), copper-based oxide and zinc-based oxide (ZnZr, ZnCr) with zeolite, as well as the combination mode of supporting and mechanical mixing on the catalytic performance are discussed. The reaction coupling and reaction condition matching are discussed, and this technology is compared with other three coal-based aromatics preparing technologies: syngas to aromatics, methanol to aromatics, and alkylation of benzene with methanol to produce aromatics, which shows that alkylation of benzene and syngas has the advantages of low cost and short process routes.

    Progress in photocatalytic selective oxidation of cyclohexane to cyclohexanone/cyclohexanol
    Zhanxin TONG, Liang SHI, Chao PENG, Chengyu LI, Hongyu QIN, Lijuan CHEN, Yujun XIANG
    2020, 39(8):  3066-3076.  doi:10.16085/j.issn.1000-6613.2019-1696
    Abstract ( 381 )   HTML ( 18)   PDF (1830KB) ( 465 )  
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    The selective oxidation of cyclohexane to cyclohexanone/ol is an industrially important process. The industrial thermal oxidation route has some disadvantages such as harsh reaction conditions, inevitable side reactions, low conversion of cyclohexane and low selectivity of cyclohexanone and cyclohexanol, which demands the development of alternative route that is more mild and environmentally friendly. The photocatalytic cyclohexane oxidation driven by sunlight can take place at normal temperature and pressure, and hence has attracted great attention. In this paper, the progress on the catalytic system, reaction mechanism and influencing factors of the photocatalytic selective oxidation of cyclohexane in last decade are reviewed. The research results on the element procedures of cyclohexane activation, cyclohexanone/ol formation and active radical regeneration as well as on the deactivation mechanism of catalysts were summarized and analyzed. In addition, the reaction parameters affecting the photocatalytic selective oxidation of cyclohexane were also analyzed and discussed in depth. It was found that ·OH was the main active radical, and cyclohexyl peroxide was the important intermediate. Cyclohexanone/alcohol was formed mainly through the photocatalytic decomposition of cyclohexyl peroxide. The light radiation parameters (incident light intensity and wavelength range), solvent and the structural and surficial properties of the catalysts are important factors affecting the reaction efficiency. Finally, it is pointed out that the key to the large-scale application of photocatalytic cyclohexane oxidation is to further improve the life and stability of the photocatalyst and to design a photocatalytic reaction device with reasonable structure and highly efficient utilization of light energy.

    Synthesis of nitriles and pyridine bases from bio-based small molecules by catalytic amination
    He ZHU, Yuecheng ZHANG, Jiquan ZHAO
    2020, 39(8):  3077-3085.  doi:10.16085/j.issn.1000-6613.2019-1722
    Abstract ( 296 )   HTML ( 7)   PDF (1304KB) ( 136 )  
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    Synthesis of nitriles and pyridine base from bio-based small molecules by catalytic amination can not only reduce the dependency on fossil resources in the production of these kinds of chemicals, but also promote the sustainable development of bio-based small molecule industry. Herein, the latest development in the conversion of ethanol and glycerol to nitriles and pyridine bases via catalytic amination were reviewed including the research results of our group. Among which, acetonitrile can be produced from ethanol with high yield. Ethanol can also be converted to pyridine bases over a catalyst with dehydrogenation activity and suitable acidity. Glycerol can be converted to nitriles or pyridine bases via either one step or two-step process, in which perfect acidity, stronger dehydrogenation-hydrogenation activity and bigger surface areas of catalysts are key facts to enable the catalysts with good performances. Two-step process generally produced nitriles or pyridine bases with much higher yield than one-step process. Deactivation of the catalysts took place due to the coke formation by irreversible adsorption of imine intermediates on the acid sites. Most deactivated catalysts can be regenerated via calcination at high temperature and in the presence of oxygen.

    Preparation of Fe2O3/modified natural zeolite catalyst and mechanism study on catalytic ozonation of 4-chlorophenol
    Lanhe ZHANG, Lin GUO, Jianing LI, Zicheng CHEN, Yanping JIA, Zheng LI, Xiaohui GUAN
    2020, 39(8):  3086-3094.  doi:10.16085/j.issn.1000-6613.2019-1735
    Abstract ( 255 )   HTML ( 19)   PDF (3168KB) ( 152 )  
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    In order to improve the efficiency of heterogeneous catalytic ozonation of refractory organic wastewater, Fe2O3/modified natural zeolite (MNZ) catalyst was prepared by impregnation method, in which the hexadecyl trimethyl ammonium bromide (CTMAB) modified natural zeolite and Fe(NO3)3·9H2O solution were used as the carrier and a precursor of active components, respectively. The structure and constituent of the catalyst were analyzed and the catalytic ozonation performance of 4-chlorophenol (4CP) as well as the catalytic mechanisms were studied by using energy dispersive spectrometer (EDS), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 adsorption/desorption, respectively. The results showed that the Fe2O3/MNZ catalyst maintained the surface structure of natural zeolite and Fe2O3 was uniformly deposited on the surface of zeolite, which confirmed the catalyst had typical molecular sieve structure. The special surface area, pore volume and pore size of the catalyst were 12.776m2/g, 0.042cm3/g and 3.932nm, respectively. The removal efficiencies of 4CP and COD were 87.26% and 48.83% when the initial concentration of 4CP, O3 concentration, temperature and pH were 100mg/L, 2.6mg/L, 25℃ and 7.0±0.2, respectively. MNZ and Fe2O3 synthetically promoted the decomposition of ozone into hydroxyl radical(·OH) with high oxidation capacity and thus improved the removal efficiency of 4CP. So, the reaction followed the mechanism of hydroxyl radical.

    Preparation of CoB/CeO2 catalysts for hydrogen generation from liquid NaBH4 solution
    Likui LIU, Wei LIU, Jia LI, Fang LI, Qiming LI
    2020, 39(8):  3095-3101.  doi:10.16085/j.issn.1000-6613.2019-0968
    Abstract ( 243 )   HTML ( 5)   PDF (1995KB) ( 110 )  
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    To improve the catalysts’ activity of NaBH4 hydrolysis, a series of CoB/CeO2 supported catalysts were prepared by a combined chemical reduction and post-calcination method. Catalytic activities of these catalysts in the hydrogen generation from NaBH4 hydrolysis were investigated. Phase structure and composition of the CoB/CeO2 supported catalysts were characterized by SEM, XRD and XPS, and the results were correlated with their catalytic performance. The experimental results indicated that the as-prepared supported CoB/CeO2 catalysts exhibited typical fluorite phase structure only, but the comparative analysis showed that significant crystallization of CoB still occurred at high temperature. CoB/CeO2 catalysts treated under air and nitrogen can have improved immobilization strength, but they displayed different surface morphologies. When used in hydrogen generation from liquid NaBH4 hydrolysis, CoB/CeO2-air and CoB/CeO2-N2 exhibited obviously different catalytic activities. Moreover, this difference tends to be more obvious at elevated treatment temperature. With the increase of calcination temperature, the catalytic activity of CoB/CeO2-air gradually decreased and even completely disappeared at 500℃, whereas CoB/CeO2-N2 maintained the catalytic activity more stably.

    MnCe based catalyst for o-xylene catalytic oxidation from coal-combustion flue gas
    Yuting WANG, Kai REN, Boxiong SHEN, Xiao ZHANG, Jiancheng YANG
    2020, 39(8):  3102-3109.  doi:10.16085/j.issn.1000-6613.2019-1687
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    The environment pollution from coal-fired combustion emission has aroused increasingly attention. MnCe based catalyst was regarded as a promising alternative catalyst for flue gas pollutants removal due to its high catalytic efficiency under low temperature and low cost. In this work, MnCe based catalysts were prepared via impregnation method for the removal of o-xylene from simulated flue gas. The effects of MnCe amount, reaction condition, the complex components in flue gas (H2O,SO2,NH3,NO) and typical pollutants on the catalytic removal of o-xylene have been investigated. The results indicated that reaction velocity and the catalyst loading amount had affected the o-xylene removal, especially at low reaction temperatures. H2O,SO2,NH3,NO in the flue gas showed inhibit effect on o-xylene removal in different degrees following different mechanisms. The mole ratio of Mn to Ce of 6∶4 showed satisfactory catalytic efficiency for o-xylene. The MnCe based catalyst exhibited good catalytic efficiencies towards NO removal and Hg0 oxidation in the flue gas, which were not obviously affected by the existence of o-xylene. However, the existence of SCR atmosphere and Hg0 had significantly inhibited the o-xylene removal.

    Materials science and technology
    Research progresses on hyper-crosslinked porous ionic polymers
    Xiaoyan XIANG, Xiaoyan LUO, Baoyou PEI, Zhaoyang ZHAO, Rongxing QIU, Xiaoyan CHEN, Jiaran LI, Ziheng ZHANG, Ruixun MA, Jinqing LIN
    2020, 39(8):  3110-3123.  doi:10.16085/j.issn.1000-6613.2019-1707
    Abstract ( 412 )   HTML ( 16)   PDF (2348KB) ( 378 )  
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    Hyper-crosslinked porous ionic polymers (HCPiPs) are a series of novel ionic organic functional materials with porous structure, large specific surface area and high charge density. Due to the advantages of mild reaction conditions, diverse preparation methods and easy functionalization, HCPiPs have made remarkable achievements in gas capture/storage, separation, catalysis, and energy storage & conversion in recent years. An overview of recent progress in the basic synthesis principles and strategies, as well as its application in the fields of gas capture/separation, heterogeneous catalysis, electrochemical energy storage, pollutant adsorption, etc., were presented. In addition, the key technical barriers on current HCPiPs preparation processes, one-step crosslinking, crosslinking-ionizing synchronous synthesis and post-modification were discussed, such as limited specific surface areas and total pore volumes, low charge density and uneven distribution, poor catalyst stability and efficiency. It was pointed out that further synthesis strategies should be focused on the design of proper pore structure and active site, content of functional ions and specific surface area, development of various new functional HCPiPs so as to expand its application fields.

    Progress of modified starch-based biodegradable plastics
    Qun LIU, Yucang ZHANG
    2020, 39(8):  3124-3134.  doi:10.16085/j.issn.1000-6613.2019-1698
    Abstract ( 578 )   HTML ( 23)   PDF (1247KB) ( 592 )  
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    Biodegradable starch-based plastics are prepared from starch to replace the traditional synthetic non-degradable plastics. It is conformed to the concept of sustainable development. Starch has the disadvantage of poor mechanical properties. It needs to be modified by physical or chemical methods to improve its mechanical properties. Starch can be modified by plasticizer, which can convert starch into thermoplastic starch. The ductility and film formation of starch can be improved through this method. The film forming and mechanical properties of materials can be obviously improved by blending starch with polymer (PVA, PLA, PBAT, etc). By blending starch with reinforcing agents (cellulose, chitosan, lignin, graphene, etc.), the mechanical properties, water resistance, thermal stability, oxygen permeability, and transparency of materials can be improved, and meanwhile the cost of materials is reduced. The flexibility of materials can be increased through adding plasticizer to starch, since plasticizer can interfere with the strong interaction between starch molecules. Starch-based biodegradable plastics can be applied widely in food, agriculture, pharmaceutical and other industries as packaging materials.

    Research progress on the interfacial compatibilizing of lignin/polyolefin composites
    Yilin YIN, Mingwei DI
    2020, 39(8):  3135-3145.  doi:10.16085/j.issn.1000-6613.2019-1829
    Abstract ( 283 )   HTML ( 10)   PDF (2798KB) ( 138 )  
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    Lignin is the second most abundant renewable biomass resource in the plant kingdom only behind the cellulose. And its effective utilization has always been the focus of people’s attention. The preparation of lignin/polyolefin composites by blending technology can not only improve the effective utilization of lignin, but also reduce the consumption of fossil energy and improve the environmental adaptability of polyolefin, which is a hot topic in recent years. However, there is a problem of poor interfacial adhesion between polyolefin and lignin, which affects the properties of composites directly, and thus improving their interfacial compatibility is very important to improve the performance of lignin/polyolefin composite. So, the structure and properties of lignin were introduced in this paper, and the reasons for the poor compatibility between lignin and polyolefin were also analyzed. Meanwhile, the research status and latest progress on lignin/polyolefin composites at home and abroad from the application of compatibilizing methods and blending process of composite materials were reviewed. The effects of compatibilizer, lignin modification method and blending process parameters on the interfacial compatibility of composites were discussed emphatically. In addition, based on the application of lignin/polyolefin composite in production and life, the development trend of interfacial compatibilization of lignin/polyolefin composite in the future was prospected. It was pointed out that searching for compatibilizers with low cost and excellent performance, compatibilizing materials multiply and introducing energy sacrifice bond would be the main research direction in the future.

    Progress on preparation and application of small-scale lignin particles
    Kai CHEN, Yungeng QI, Yanzhu GUO, Shi WANG, Haiming LI
    2020, 39(8):  3146-3162.  doi:10.16085/j.issn.1000-6613.2019-1850
    Abstract ( 352 )   HTML ( 12)   PDF (2520KB) ( 266 )  
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    Small-scale lignin particles are new products for high-value utilization of lignin. Due to their excellent physicochemical properties and potential application value, such as non-toxicity, corrosion resistance, antibiosis and antioxidation, they have attracted extensive attention and have been studied and developed by scientific researchers. In this paper, the preparation technologies of small-scale lignin particles, including self-assembly method, antisolvent method, interfacial polymerization/crosslinking method, high shear homogenization method, ultrasonic wave method, ultrasonic spray freezing method, microbial method and enzymatic method, etc., were reviewed. Subsequently, the preparation principle, preparation conditions and product characteristics of small-scale lignin particles prepared by different lignin raw materials and different methods were expounded. Then, the main preparation process parameters, physical and chemical characteristics and main size characterization methods of small-scale lignin particles were summarized and compared. In addition, the research progress on the application of small-scale lignin particles in ultra-violet protection, composite materials and drug delivery carriers was briefly introduced. In the end, the main problems existing in the preparation and application of small-scale lignin particles at the present stage and the future development direction were analyzed compendiously in order to provide reference for the research and development of lignin in forest resource deep processing and biomass-based nanomaterial science and technology.

    Application of metal-organic frameworks materials in adsorptive desulfurization
    Xuan LIU, Yingna CUI, Jingmei YIN, Changping LI
    2020, 39(8):  3163-3176.  doi:10.16085/j.issn.1000-6613.2019-1790
    Abstract ( 363 )   HTML ( 8)   PDF (2099KB) ( 524 )  
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    SOx from the combustion of sulfur compounds in fuel is one of the main sources of environmental pollution. In recent years, with the increasingly strict environmental regulations,deep desulfurization of fuel has become a top priority. Adsorption desulfurization (ADS) has the advantages of low energy consumption, mild conditions, simple operation and efficient reaction. It is considered to be one of the most promising technologies for achieving deep desulfurization. Currently, as a new member of porous material family, metal-organic frameworks (MOFs) have shown good desulfurization performance. This article reviewed the most up-to-date progress of MOFs in adsorption desulfurization in the past 10 years. Firstly, the different types of MOFs such as IRMOFs, ZIFs, MILs, PCNs, HKUST-1, UiOs and CPOs were described. The representative materials in each types of MOFs were introduced in detail, and the research and application progress of MOFs in adsorption desulfurization were summarized. The desulfurization effect, regeneration and recycling of MOFs were analyzed. Then, the mechanisms of adsorption desulfurization and the stability of MOFs were summarized. Finally, the key problems of the applications of MOFs to be solved in future were also mentioned. The future development prospects of MOFs in fuel adsorption desulfurization were prospected.

    Preparation and properties of super-hydrophobic polyvinylidene fluoride microporous membrane supported on deposited magnesium alloy
    Zhiying WANG, Haijing ZHANG, Peiying ZHANG, Zhensheng YANG, Chunli LI
    2020, 39(8):  3177-3182.  doi:10.16085/j.issn.1000-6613.2019-1315
    Abstract ( 277 )   HTML ( 9)   PDF (2502KB) ( 94 )  
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    Magnesium alloy with coarse coating was prepared by one-step immersion method, on which polyvinylidene fluoride (PVDF) membrane was fabricated by dry-wet phase inversion in PVDF/dimethylacetamide(DMAc) and octanol/water. The obtained membrane exhibited super-hydrophobicity with a water contact angle up to 160°. Rough-meter,scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) were employed to analyze the structure and compositions of the substrate and membrane surface. It was revealed that a layer of uniform ferrous tetradecanoate was formed on the magnesium alloy substrate, some of which moved to the bottom of the PVDF membrane resulting in the increase of the surface roughness and hence the increase of the hydrophobicity. Attrition tests showed that the super-hydrophobic membrane possessed good mechanical stability as well. When used in vacuum membrane distillation, the membrane showed high permeation and rejection coefficients, and great stability.

    Effect of branch structure on rheological properties of dendritic polymer before and after shearing
    Nanjun LAI, Xiaohu WEN, Wensen ZHAO, Yong WANG, Xubin ZHAO, Dan ZHOU
    2020, 39(8):  3183-3196.  doi:10.16085/j.issn.1000-6613.019-1682
    Abstract ( 267 )   HTML ( 5)   PDF (4439KB) ( 121 )  
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    In this paper, the effect of different branching degree on the rheological properties of dendritic polymers before and after shearing was studied by using the Warning Mixing Speed Governor to simulate the shearing action of polymer in its preparation, transportation and injection. Firstly, the changes of viscosity before and after shearing of dendritic polymer solutions with different degree branching at different polymer concentrations, different shear times and different shear strengths were analyzed. Three kinds of dendritic polymers with different degrees of branching were prepared, and the molecular size distribution and molecular weight of the dendritic polymers before and after shearing were studied. Moreover, the effects of different factors on the rheological properties of the dendritic polymers were studied and the viscoelastic properties of the dendrimer solution were analyzed. Finally, the effects of the branched structure on the rheological properties of dendritic polymer solutions before and after shearing were analyzed by environmental scanning electron microscopy. The results showed that the dendritic polymers with higher degree of branching had larger hydrodynamic radius and molecular weight and were less affected by the environment. The dendritic polymer solutions exhibited pseudoplastic fluid characteristics. The higher the degree of branching is, the smaller the power law index n of the polymer solution before and after shearing, and the greater the consistency coefficient K. The higher the degree of branching is, the more easily the entanglement between dendritic polymer branches is to form a dense, multi-layered spatial network structure, resulting in better rheological properties of the polymer solution before and after shearing.

    Molecular simulation and experimental demonstration of adsorption behavior of emulsifier on surface of chemical composition of aggregate
    Lingyun KONG, Xiujie QUAN, Chaobo LI, Miao YU
    2020, 39(8):  3196-3204.  doi:10.16085/j.issn.1000-6613.2019-1774
    Abstract ( 242 )   HTML ( 8)   PDF (2523KB) ( 100 )  
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    The adsorption behavior of sodium dodecyl benzene sulfonate(SDBS) and octadecyl trimethylammonium chloride (STAC) on the surface of the main chemical components of acidic aggregate (SiO2) and basic aggregate (CaCO3) was studied by means of molecular simulation and conductivity test. The simulation results show that there are two hydration layers around the two types of emulsifiers. The number of water molecules in the first hydration layer of the hydrophilic group of STAC is about twice that of SDBS, which is more hydrophilic than SDBS. According to the analysis of interface energy, for two types of emulsifiers, the adsorption capacity of STAC on the surface of the main chemical components of the aggregate is greater than SDBS. For both types of aggregates, the adsorption capacity of CaCO3 for the two types of emulsifiers is stronger than that of SiO2. The conductivity test results show that: under different aggregate ratios (mass ratio of emulsifier to aggregate chemical composition), the adsorption amount of emulsifier on the surface of CaCO3 is greater than SiO2, and with the increase of aggregate ratio, the chemical composition of different aggregates adsorption of emulsifiers also increased. The adsorption curves of CaCO3 and SiO2 for the two types of emulsifiers are approximately S-type, and the dispersion of the adsorption curves for STAC is less than SDBS. SDBS and STAC have the highest surface concentration (Γ1) on CaCO3, and the maximum adsorption capacity of STAC is about 3.2 times that of SDBS. The gray correlation between the coordination number of simulation parameters and the maximum adsorption amount and the adsorption coefficient of emulsifier is good. The coordination number can be used to analyze the hydrophilicity of the emulsifier, and the maximum adsorption capacity and adsorption coefficient can be used to judge the amount of the emulsifier adsorbed by the aggregate. The simulation results are consistent with the experimental results, indicating that molecular dynamics can accurately describe the adsorption behavior of emulsifier on the surface of main chemical components of the aggregate.

    Absorption properties of hollow fiber membranes of different materials for flue gas desulfurization
    Chaopeng YANG, Jie LIU, Hongda SHI, Zhiyong JI, Yingying ZHAO, Junsheng YUAN
    2020, 39(8):  3205-3212.  doi:10.16085/j.issn.1000-6613.2019-1607
    Abstract ( 224 )   HTML ( 4)   PDF (2020KB) ( 89 )  
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    Flue gas desulfurization with membrane has low energy consumption, large mass transfer area and high separation efficiency, which can effectively solve the problems of liquid flooding, liquid leakage and entrainment in traditional towers. The absorption performances of FTEE, PVDF and PP hollow fiber membranes applied in sulfur dioxide absorption were compared by a self-made membrane contactor. The effects of flue gas flow rate, water flow rate and water temperature in different membrane were investigated. The membrane parameters and hydrophobicity of these three membranes were detected and compared by scanning electron microscope and contact angle measuring instrument. The absorption performances of three membranes were in ascending order of PTFE>PP>PVDF under all the different conditions. In terms of the absorption concentration of sulfur dioxide in 120min, the maximum ratio of PTFE to PP was 1.68∶1, and the maximum ratio of PTFE to PVDF was 4.62∶1. The change of gas flow had a significant effect on the absorption of sulfur dioxide. When the flue gas flow rate increased from 60mL/min to 140mL/min, the absorption capacity of PTFE was obviously enhanced, and in 120min, the absorption concentration of sulfur dioxide increased by 2.14 times. The hydrophobicity was the main parameter that affected membrane performance. The surface contact angles of PTFE before and after immersion were 105° and 97°, respectively, and the hydrophobicity was much stronger than PP and PVDF. Among all, PTFE hollow fiber membrane had large pore size, high porosity, high hydrophobicity. Especially its good temperature resistance could highly reduce the cooling procedure of flue gas. These advantages made it a good application prospect in flue gas desulfurization process.

    Preparation of nano zinc oxide/silica hybrid and its effect on properties of natural rubber composites
    Yihang LI, Yuzhu XIONG, Qingpo ZHANG, Jiangbing WU
    2020, 39(8):  3213-3220.  doi:10.16085/j.issn.1000-6613.2020-0409
    Abstract ( 248 )   HTML ( 2)   PDF (3136KB) ( 265 )  
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    SiO2 particles were cyano-functionalized by 3-cyanopropyltriethoxysilane (CTOS), and ZnO/SiO2 hybrids (ZnO@SiO2) were produced by deposition of the ZnO nanoparticles on cyano-functionalized SiO2 (SiO2-CN) surface via a facile solvothermal method. The hybrid structures were analyzed by X-ray diffractometer, Fourier transform infrared spectrometer and scanning electron microscope. ZnO@SiO2 was used as a filler to prepare NR/ZnO@SiO2 composites, and the interface relationship between ZnO@SiO2 and rubber was studied. In addition, the influence of ZnO@SiO2 on the vulcanization characteristics and mechanical properties of rubber composites was analyzed. As a result, ZnO nanoparticles was successfully deposited on the surface of SiO2-CN, and NR/ZnO@SiO2 composites exhibited excellent mechanical properties and vulcanization characteristics. Compared with natural rubber, the tensile strength, stress at 100% strain, and stress at 300% strain of NR/ZnO@SiO2 composites with 5 phr hybrids were superlatively increased by 150.2%, 86.2% and 65.5%, respectively, and the curing time was reduced by 38.5%.

    Preparation and properties of PBT/TPU/DOPO-MA flame retardant composites
    Jiyong LUO, Daohai ZHANG, Mi ZHOU, Qin TIAN, Shuhao QIN
    2020, 39(8):  3221-3229.  doi:10.16085/j.issn.1000-6613.2019-1791
    Abstract ( 327 )   HTML ( 6)   PDF (5285KB) ( 241 )  
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    The DOPO derivative flame retardant (DOPO-MA) was synthesized via the synthetic reaction of DOPO and maleic anhydride. Its structure was characterized through Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance proton spectroscopy (1H NMR) techniques. The flame retardant was melt-blended with polybutylene terephthalate (PBT) and thermoplastic polyurethane (TPU) for the synthesis of PBT/TPU/DOPO-MA flame retardant composite. The performance of flame retardants on composites was investigated based on cone calorimeter, UL-94, limiting oxygen index (LOI), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and mechanical tests. The results showed that the PBT/TPU/DOPO-MA composite materials had good flame-retardancy performance. The LOI increased from 23.2 to 31.6 with additional 10% DOPO-MA, which could reach the UL-94 V-1 level. In addition, the decrease in peak heat release rate (PHRR) and the maximum heat radiation rate (MAHRE) was observed. The results based on thermogravimetric analysis revealed that the DOPO-MA introduced could improve the thermal stability of flame-retardant composites significantly. The amount of residual carbon increased from 6.87 to 14.36 with the addition of 10% DOPO-MA. Furthermore, the crystallinity of flame-retardant composites could be improved with the increase of DOPO-MA content.

    Liquid low molecular polyisoprene modified nitrile rubber foaming materials
    Wenyu WANG, Ruibao DONG, Zhibo LI, Guangqin PAN
    2020, 39(8):  3230-3235.  doi:10.16085/j.issn.1000-6613.2019-1755
    Abstract ( 230 )   HTML ( 23)   PDF (1344KB) ( 95 )  
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    The effect of microstructure of four grades of nitrile rubber (NBR) on vulcanization rate of NBR was studied by means of NMR, and the method of increasing the vulcanization rate of NBR was explored. The results show that there are three olefin structures in the NBR molecular chain: cis 1,4-polybutadiene, trans 1,4-polybutadiene and 1,2-vinyl.1,2-Vinyl has a correlation with the vulcanization rate of NBR. When the 1,2-vinyl content is high, the vulcanization rate is fast. The low molecular weight polyisoprene (LLPI) as a modifier of NBR increases the vulcanization rate of NBR and improves the NBR processability and mechanical properties of the foamed material. The tensile strength of foamed materials with 5 parts of LLPI increased by 14.2% and the elongation at break decreased by 27.1%. And LLPI can form cross-linking network and improve the tightness of cross-linking structure, reduce the melt strength of the rubber compound, and make the foaming of the foaming material good.

    Biochemical and pharmaceutical engineering
    Research progress in DHA production by thraustochytrids
    Huike YE, Qiuzhen WANG, Yaodong HE, Guangyi WANG
    2020, 39(8):  3235-3245.  doi:10.16085/j.issn.1000-6613.2019-1764
    Abstract ( 328 )   HTML ( 18)   PDF (1511KB) ( 237 )  
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    Docosahexaenoic acid (DHA) is a very important polyunsaturated fatty acid, which plays a crucial role in many physiological processes in humans and animals. Because of fast growth rate and high DHA content, thraustochytrids show great potential in large-scale DHA production. In this paper, the DHA synthesis pathway, culture conditions affecting DHA production and the current status of pilot scale fermentation by thraustochytrids were introduced. Firstly, two DHA metabolic pathways of thraustochytrids including fatty acid synthase (FAS) pathway and polyketide synthase (PKS) pathway were summarized and described. Subsequently, three factors affecting DHA production by thraustochytrids, namely carbon and nitrogen sources, dissolved oxygen and temperature, were discussed. Then, the pilot scale up of DHA production by thraustochytrids was reviewed. Finally, the existing problems in the production of DHA by thraustochytrids were pointed out, indicating that future research emphasis should be given to screening high quality strains, investigating the key enzyme in the DHA biosynthesis and studying the pilot scale up technology. This article would be useful for the industrialized production of DHA by thraustochytrids.

    Study on preparation and properties of hemicellulose abamectin-loaded microcapsule
    Linya ZHANG, Wei XUE, Limin GU
    2020, 39(8):  3246-3255.  doi:10.16085/j.issn.1000-6613.2019-1552
    Abstract ( 307 )   HTML ( 5)   PDF (2698KB) ( 160 )  
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    Abamectin has been widely used due to its high efficiency, pollution-free, and less drug resistance, but its poor stability and easy degradation lead to a large amount of utilization and waste. To solve the problems, abamectin-loaded microcapsule (HDCM) based on hemicellulose was prepared by in-situ polymerization. By studying preparation conditions, thermal degradation, storage stability and release kinetics, drug loading, thermal stability and release performances of HDCM were determined. The results showed that the drug loading of HDCM could reach 66.5%, and it had small particle size and uniform dispersion under the preparation conditions of the core-wall mass ratio of 1∶34, temperature of 65℃ and pH of 3.5. The thermal degradation performance and constant temperature thermal stability of HDCM were improved compared to avermectin agent. The maximum temperature of thermal decomposition was increased from 261℃ to 272℃. After 10h, the degradation rate of avermectin agent reached 12.1%, and the degradation rate of HDCM with the drug loading of 66.5% was only 5.2%. The release mechanism on HDCM satisfies Fick diffusion. The cumulative release rate of avermectin agent in water reached 83.8% within 12h, while the cumulative release rate of HDCM gradually increased after 24h. Within 12h the release rate of HDCM was only 33.7%, indicating that HDCM had excellent sustained release performance.

    Characteristics of anaerobic fermentation in CSTR, VPF and BVPF for yellow storage of corn straw
    Hao JIANG, Fan WU, Lei YU, Mingyu QIAN, Hongjun ZHOU, Yeqing LI
    2020, 39(8):  3256-3262.  doi:10.16085/j.issn.1000-6613.2019-1843
    Abstract ( 218 )   HTML ( 4)   PDF (1367KB) ( 121 )  
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    In order to improve the efficiency of anaerobic fermentation and the utilization rate of straw, the corn straw could be pretreated with physical and biological methods to form yellow storage of corn straw (YSCS). In this study, the fermentation performances of YSCS in different kinds of reactors were comprehensively investigated, including vertical plug flow (VPF) reactor, continuous stirred tank reactor (CSTR) and baffled vertical plug flow (BVPF) reactor which was upgraded from VPF reactor. In the VPF reactor, YSCS could perform well when the organic loading rate (OLR) was 0.5gVS/(L·d). However, it was difficult to discharge the materials with the increase of OLR. Besides, CSTR had a stirring sector, and thus the reactor could reach gas production equilibrium quickly. When OLR was 1gVS/(L·d), the time required for BVPF to reach stability was 7 days longer than that of CSTR. After it finally reached stability, the gas production per volatile solid (VS) in CSTR and BVPF reactors were 390.9mL and 382.4mL, respectively. When OLR was 2gVS/(L·d), BVPF needed two more days to reach equilibrium comparing to CSTR, and the gas production per VS of CSTR and BVPF reactors were 291.3mL and 294.9mL, respectively. In addition, pH and VFA/TIC values of all three reactors remained stable during the operation stage. After the increase of OLR, BVPF and CSTR were able to reach new equilibrium. These results indicated that VPF reactor could be used under the condition of low OLR. The time required for the CSTR to reach a steady state was short, but the gas production efficiency of the CSTR and BVPF was basically the same during stable operation. In conclusion, owing to the lower energy and water consumption, BVPF would have a promisingly commercial application prospect.

    Model building and transfer between spectrometers in the application of near infrared spectroscopy to online quality control of Chinese herbal liquid tonic
    Liping HU, Shengquan HUANG, Shuhua TIAN, Yansheng HUANG, Liuyun HU, FALOLA Akinola A, Xuan LI, Yidan SHU, Xue Zhong WANG
    2020, 39(8):  3263-3272.  doi:10.16085/j.issn.1000-6613.2019-1569
    Abstract ( 237 )   HTML ( 4)   PDF (2411KB) ( 93 )  
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    In the industrial application of near infrared spectroscopy (NIR) to on-line monitoring of product quality, it is not uncommon that the application environment is changed or instrument components e.g. the probe head or the fiber are replaced, leading to a situation that the original model no longer performs as satisfactory as before, but building completely new models by collecting new calibration data means huge task and waste of the previous valuable model and data. In order to solve the dilemma, by reference to the study on NIR application to on-line real-time monitoring of the polysaccharide content, soluble solid content and pH in the manufacture of a Chinese herbal medicine oral liquid, this paper has investigated model transfer methods between the master (original) NIR spectrometer and the slave (new) spectrometer in which the resolution of the two is different. Using the model that had been built and successfully applied to the original spectrometer as the master model, in the absence of a reference sample to which both the original (master) and the new (slave) spectrometers could be applied, a virtual reference between the two spectrometers was established, and a matrix for mode transfer was thus constructed. The method of direct standardization (DS) combined with principal component analysis (PCA) dimension reduction was used as the model transfer approach, and the best model was selected by using the relative error between the chemical index and the predicted value of the quality index. The result indicates that the relative errors can be controlled within 10% for polysaccharides between the predictions of the model and the chemical reference values, within 5% for soluble solids, and within 4% for pH. The online use shows that the transferred model can be effectively applied to the online and rapid prediction of quality indicators like the original model. The result proves the effectiveness of the model transfer approach presented in this work that makes use of virtual reference samples in applications where no one to one corresponding spectra for the same sample are available.

    Separation of 1,2,4-butanetriol by aqueous two-phase extraction
    Xuanhui DU, Fangyuan QIAN, Xinyao LU, Hong ZONG, Bin ZHUGE
    2020, 39(8):  3273-3277.  doi:10.16085/j.issn.1000-6613.2019-1801
    Abstract ( 315 )   HTML ( 5)   PDF (1049KB) ( 140 )  
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    Aqueous two-phase systems composed of organic solvents and inorganic salts could be used to extract 1,2,4-butanetriol (BT) from fermentation broth. Through the screening of several aqueous two-phase systems, the absolute ethanol/K2HPO4 two-phase system was finally selected to separate BT. The absolute ethanol/K2HPO4 two-phase system was investigated in detail, including phase diagram, and effect of phase composition on partition and pH. The results indicated that the phase could be formed in the range of the mass fraction of K2HPO4 being 19.83%~46.87%. The highest partition coefficient (18.35) and recovery (95.87%) of BT were obtained with an aqueous two-phase system composed of the system total 10g, 28% (mass ratio) absolute ethanol, 28% (mass ratio) K2HPO4 and pH 9.5. Under the optimal extraction condition, the system was further subjected to amplification experiments. The result showed that the amplification experiment had less influence on the distribution coefficient and recovery, which proved that the absolute ethanol/K2HPO4 two-phase system had high stability and potential for industrial application.

    Fine chemicals
    Synthesis and properties of Gemini surfactant containing polyfunctional groups
    Liyan WANG, Jia YANG, Yunqing LI, Li TANG, Jiaqing LIU, Yuying DU, Dingcheng WU
    2020, 39(8):  3278-3286.  doi:10.16085/j.issn.1000-6613.2019-1570
    Abstract ( 242 )   HTML ( 5)   PDF (2155KB) ( 138 )  
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    A series of Gemini surfactant (I8, I12,I14, I16) containing polyfunctional group were synthesized by using chloroacetyl chloride, isophthaloyl chloride, long alkyl chain primary amine(carbon chain length was 8,12,14,16), and N,N-dimethylethanolamine as main raw materials. The structures of product were characterized by FTIR and 1H NMR. The critical micelle concentrations (CMC) and the relevant thermodynamic parameters (, , ) were determined at different temperatures by electrical conductivity measurements. The surface tensions (γCMC) were determined by surface tension method at 298.15K. The foaming properties and emulsifying properties were investigated. The results show that target products have lower CMC values, and the lowest CMC value reaches 0.05mmol/L at 298.15K. The minimum value of γCMC for I16 is 36.14mN/m. Foam properties and emulsification test results show that I8 exhibits the best foaming ability; I12 and I14 exhibit the best foam stability (100%) at 298.15K. As emulsifying agent for benzene and xylene the target products have good emulsifying properties. Among these products, I12 has the best emulsifying properties for xylene, and the emulsification time is 900s; I16 has the best emulsifying properties for benzene, and the emulsification time is 629s.

    Colorimetric recognition of Cu2+ and fluorescence recognition of Zn2+ by s-triazine derivatives
    Limei LI, Meige WANG, Qiusheng YANG, Zhongyu DUAN
    2020, 39(8):  3287-3292.  doi:10.16085/j.issn.1000-6613.2019-1690
    Abstract ( 217 )   HTML ( 2)   PDF (2666KB) ( 124 )  
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    Two ion probes 1 and 2 with s-triazine symmetric structure were synthesized with 4-aminobenzonitrile, 2-tert-butylphenol and 3,5-di-tert-butylsalicylaldehude as raw materials and its structure was characterized by 1H NMR, 13C HMR, IR and mass spectrometry. The recognition performance of probes 1 and 2 for metal ions(Cr3+,Mn2+,Fe3+,Co2+,Ni2+,Cu2+,Zn2+,Cd2+,Hg2+) in the N,N-dimethylformamide (DMF) were investigated by UV-vis spectra and fluorescence spectra. Then, the mechanism of forming complexes with probe 1 and Zn2+ was discussed by 1H NMR. It was found that the fluorescence intensity of probe 1 had a significant increase after adding Zn2+ to the probe 1 solution. Probe 1 was a fluorescently enhanced probe and had the selective recognition to Zn2+. The color of solution of probe 2 in DMF was changed from colorless to yellow after adding Cu2+, and a new absorption peak appeared at the long wavelength of UV-vis spectrum. Probe 2 was a highly efficient UV probe for Cu2+ that can be recognized by naked eye.

    Resources and environmental engineering
    Research advances on applying carbon materials to activate persulfate in advanced oxidation technology
    Pengfei XIAO, Lu AN, Shuang HAN
    2020, 39(8):  3293-3307.  doi:10.16085/j.issn.1000-6613.2019-1833
    Abstract ( 554 )   HTML ( 26)   PDF (2459KB) ( 590 )  
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    In the degradation process of organic pollutants using activated persulfate oxidation technology, it is very important to develop new activation technology which is economical, efficient and safe, and it has become a research hotspot. In recent years, carbon materials, with their unique advantages and promising application prospects, have been widely concerned, and are expected to become a new generation of green catalysts for advanced oxidation technology. In this paper, the latest research progress on the application of various carbon-based materials including activated carbon, different types of biochar, surface modified carbon materials, heteroatom modified carbon materials, and metals and metal oxides loaded carbon materials for persulfate activation and carbon materials coupling with other technologies to activate persulfate to degrade organic pollutants are deeply reviewed. In addition, the operating cost of activated persulfate oxidation technology with carbon materials and other different methods is discussed. Finally, the current challenges and future development direction of carbon materials in persulfate based advanced oxidation technology are put forward. This review may provide a reference for the further popularization and application of carbon materials on catalyzing persulfate advanced oxidation reaction to degrade organic pollutants.

    Research progress of catalytic ceramic filter tubes for synergistic removal of flue gas pollutants
    Ge LI, Baodong WANG, Ziran MA, Chunlin ZHAO, Jiali ZHOU, Hongyan WANG
    2020, 39(8):  3307-3319.  doi:10.16085/j.issn.1000-6613.2019-1732
    Abstract ( 329 )   HTML ( 20)   PDF (2225KB) ( 303 )  
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    The emission of various pollutants in the combustion flue gas is the most important source of air pollution, and it is of great significance for the control of multi-pollutants of flue gas. This paper reviews two technologies at home and abroad regarding the removal of multi-pollutants from flue gas: traditional tandem removal technology and integrated synergistic removal technology. Compared with the traditional tandem removal technology, the multi-pollutant integrated synergistic removal technology has the advantages of high system efficiency, long service life, small floor space, low operating cost and wide application fields, and is the development trend of multi-pollutant treatment of flue gas. The ceramic filter tube catalyst technology has become a promising integrated synergistic removal technology with its unique asymmetric and pore size gradient structure. The researches on ceramic filter tube catalysts at home and abroad were mainly focused on the selection of filter tube and the process of denitrification catalyst loading. The research on the catalytic activity, filtration pressure drop and performance stability of the catalyst around the filter tube has achieved certain results. Based on the current research status of ceramic filter tube catalysts, this paper puts forward some suggestions for the development of catalyst technology for flue gas multi-pollutant ceramic filter tubes.

    Advances in resource utilization of oxygenated compounds in Fischer-Tropsch synthesis products
    Qi ZHANG, Tao WANG, Xuebing ZHANG, Xiangkun MENG, Yijun LYU, Zhuowu MEN
    2020, 39(8):  3320-3332.  doi:10.16085/j.issn.1000-6613.2019-1832
    Abstract ( 333 )   HTML ( 7)   PDF (1786KB) ( 521 )  
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    The Fischer-Tropsch synthesis (FTS) product contains various high value-added oxygenates. Lower carbon number oxygenates dissolve in the synthetic water, leading to the characters of strong acidity, high corrosion, pungent odor and difficult to be treated by bioprocess directly. Herein, realizing the targeted resources utilization according to the actual composition of FTS synthetic water is necessary. Only in this way can the economic and environmental benefits be maximized. With the development of indirect coal liquefaction industry, FTS synthetic water treatment technology has attracted increasing attentions from researchers. This article analyzed the compositional properties of FTS synthetic waters produced by different FTS technologies. Extraction and separation technologies for high value-added oxygenates that consists of oil separation, acid separation, and alcohol separation are reviewed. The technical advances in FTS synthetic water quality upgrading are also introduced. Also, the application and implementation performances of industrialized FTS synthetic water treatment technologies both domestic and overseas are summarized. At last, the future development direction of FTS synthetic water treatment including the improvement of high-efficiency integrated technologies, the expandable of the feedstock range, the reduction of energy consumption, as well as the reduction of the usage of various additives are outlooked.

    Microplastics pollution in freshwater environment
    Xingxing CHEN, Min LIU, Ying CHEN
    2020, 39(8):  3333-3343.  doi:10.16085/j.issn.1000-6613.2019-1787
    Abstract ( 504 )   HTML ( 30)   PDF (1193KB) ( 494 )  
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    Microplastics have long stayed in freshwater systems because of their larger surface area and hydrophobic characteristics, and microplastics pollution in freshwater has attracted wide attention from scholars and the public at home and abroad. In order to assess the environmental risks of microplastics in a more comprehensive way, this paper summarizes the current pollution status of microplastics in freshwater environment, the adsorption of microplastics to pollutants, the biotoxicity of microplastics to freshwater organisms and the control of microplastics pollution. Microplastics can be divided into primary and secondary microplastics. They are widely distributed in reservoirs, lakes, rivers and other waters, where population density and human activities, seasonal and hydrological characteristics affect microplastics distribution in freshwater. Microplastics have different degrees of adsorption to traditional pollutants such as heavy metals, polycyclic aromatic hydrocarbons and emerging pollutants such as antibiotics, and the adsorption behavior of microplastics is related to the properties of microplastics, the hydrophobic nature of pollutants and environmental factors such as pH, ion strength, temperature and dissolved organic matter in the water environment. In addition, microplastics can accumulate in freshwater organisms and cause physical, biochemical and other damage to aquatic organisms, while microplastics can carry pollutants to cause compound effects. Therefore, microplastics pollution needs to be controlled, control methods mainly include source control, the removal of microplastics in sewage treatment plants and the remediation of microplastics pollution.

    A review on photochemical reaction via organic triplet excited state
    Yantong CHEN, Xudong LI, Ye TAO, Hongying HUANG, Zhaolian YE, Xinlei GE
    2020, 39(8):  3344-3353.  doi:10.16085/j.issn.1000-6613.2019-1754
    Abstract ( 458 )   HTML ( 18)   PDF (1460KB) ( 417 )  
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    Photochemical reactions include direct photolysis and indirect oxidation, in which the indirect oxidation is mainly triggered by reactive oxygen species (ROS), including singlet oxygen (1O2), superoxide (O2-) and hydroxyl radical (·OH). In recent years, organic triplet excited state (generally refer to as 3C*), as a special oxidant, has attracted extensive attention in photochemical reactions. In this paper, the formation and photochemical reaction mechanism of organic triplet photosensitizers, the environmental photochemical reactions in which 3C* participates, the lifetime of 3C*, the determination of reaction rate and steady concentration, as well as the application of triplet excited states were reviewed. Meanwhile, the research direction of triplet excited states of organic molecules in the future is prospected. It was pointed out that 3C* was an important sink of VOCS and semi-/intermediate VOCs (S/IVOCs)in the atmosphere. The triplet states of dissolved organic matter (3DOM*) in natural water was the main oxidant for pollutant degradation. In the future, the research scope of the reaction of 3C* with organic matter and the determination of steady concentration and production rate (quantum yield) of 3C* in different systems should be extended in order to provide theoretical basis for pollutant treatment.

    Effect of nano-LaF3 on the granular flow lubrication behavior of biomass fuel soot
    Tianxia LIU, Kai KANG, Jian WANG, Zhanqi TANG, Xianguo HU
    2020, 39(8):  3354-3361.  doi:10.16085/j.issn.1000-6613.2019-1714
    Abstract ( 240 )   HTML ( 7)   PDF (6142KB) ( 81 )  
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    In order to explore the effect of soot particles on the friction pair interface of engine and the role of lubricating oil additives under extremely starved oil condition, a reciprocal friction and wear tester was performed to investigate the effect of nano-LaF3 on the granular flow lubrication behavior of biomass fuel soot (BS) particles under reciprocating friction condition. The roles of the nano-LaF3 between rubbing surfaces were analyzed by the Raman spectrometry, 3D laser scanning microscope and X-ray photoelectron spectrometer. Results showed that the wear resistance and friction reduction of friction pairs could been significantly improved under reciprocating sliding conditions as the addition mass fraction of the nano-LaF3 was more than 20%. With the increasing of nano-LaF3 content, the graphitization degree of soot was increased on the wear surface. Meanwhile, the graphite crystallite size was increased. The lubrication mechanisms of the nano-LaF3 for BS granular flow lubrication under sliding condition were attributed to the formation of tribo-films including LaF3 and other lanthanum compounds, carbon oxides and iron oxides on the wear surface. At the same time, the nano-LaF3 would induce the more graphite transition of soot under the sliding condition which sequentially enhanced the antifriction ability of BS granular flow lubrication.

    Flotation mechanism of rutile in synergistic systems composed by sodium oleate and hydroxylamine-type reagents
    Mingbao LIU, Wanzhong GUO, Wanzhong YIN
    2020, 39(8):  3362-3370.  doi:10.16085/j.issn.1000-6613.2019-1654
    Abstract ( 230 )   HTML ( 9)   PDF (2120KB) ( 177 )  
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    Flotation response of rutile in combined reagent systems composed by sodium oleate(SO) and hydroxylamine-type reagents was studied using pure mineral flotation test. Several techniques, namely zeta potential, contact angle, surface tension and UV spectroscope, were exploited to investigate the interaction mechanisms of the reagent combination at gas-liquid and solid-liquid interface in terms of interface chemistry properties. The results indicated that the collecting ability of the three reagents followed the order: sodium oleate (SO, 51.55%)>cupferron (CF, 18.72%)>neocupferron (NF, 14.01%)。The magnitude of effect of reagent adding order on rutile recovery was adding CF prior to SO>adding SO prior to CF>premixing SO and CF before adding> premixing SO and NF before adding>adding SO prior to NF>adding NF prior to SO, which was coincidence with the sequence of the synergism indexes. The electron conjugation effect, existing between the double bond in sodium oleate and the benzene ring or naphthalene ring bearing in hydroxylamine-type reagents, had a great impact on the adsorption and the association properties of the reagents. The amount and the configuration of complex formed by reagents play a leading role in rutile flotation behaviors.

    Industrial application of efficient organic sulfur removal solvent CT8-24
    Chaoyue YANG, Hua YI, Ke LIU, Jinlong HE, Wei NI, Honggang CHANG, Chao HU, Tianyou HU, Shiming CHEN, Wenke CHEN
    2020, 39(8):  3371-3379.  doi:10.16085/j.issn.1000-6613.2019-1775
    Abstract ( 278 )   HTML ( 11)   PDF (1424KB) ( 110 )  
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    Due to the low removal rate of organic sulfur by MDEA, it cannot meet the requirements for pipeline natural gas in GB 17820—2018. To solve this problem, the natural gas research institute has developed an efficient organic sulfur removal solvent (CT8-24). On the basis of indoor research and intermediate scale-up test, the industrial application is carried out on the 400×103m3/d unit imported from Chongqing natural gas purification plant of PetroChina Southwest Oil and gas field company. The absorption performance of the solvent under different absorption tower plate number, regeneration temperature and circulation quantity of the solution was investigated, and the appropriate process parameters were determined. The results of industrial application showed that the operation of the unit was stable after transforming MDEA aqueous solution into CT8-24 solvent. Under the 35 layer absorption tray, the H2S content in the product was less than 6mg/m3 and the total sulfur was less than 20mg/m3. The product gas met the latest requirements of GB 17820—2018. In addition, the adaptability of physical-chemical solvent to MDEA desulfurization unit was studied, which laid a solid foundation for the transformation of other purification plants.

    Electroosmotic dewatering of high salinity organic pharmaceutical wastewater sludge
    Jinting YUAN, Rui ZENG, Li SHA, Liming LIN, Kaiqiang ZHANG, Shuting ZHANG
    2020, 39(8):  3380-3385.  doi:10.16085/j.issn.1000-6613.2019-1820
    Abstract ( 279 )   HTML ( 4)   PDF (1690KB) ( 137 )  
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    In order to study the performance of electroosmotic dewatering process in high salinity organic pharmaceutical wastewater sludge and further understand the electroosmotic dewatering process of chemical sludge, the deep dewatering of filtrating dewatered high salinity organic pharmaceutical wastewater sludge by electroosmotic technology was investigated in this study. The effects of initial pH value on moisture content, current, conductivity, pH, zeta potential and energy consumption of the anode and cathode sludge during the electroosmotic dewatering process were evaluated, and the feasibility of electroosmotic dewatering process of high salinity organic pharmaceutical wastewater sludge was verified. The mechanism of electroosmotic dewatering of chemical sludge was discussed. The results showed that when the pH values of sludge cake was 2,3 and 4, respectively, zeta potential was positive, and electroosmotic flow was reversed, so it was unable to dehydrate. When pH increased to 5, zeta potential became negative, electroosmotic flow was removed from the cathode, and the moisture content of sludge was decreased from 53.2% to 44.8%. However, the dewatering amount decreased when the pH increased to 6. The conductivity of sludge decreased with the pH increasing. When the pH was 5, the initial current reached the maximum value. When the moisture content of sludge decreased to 45.5% after dewatering for 15min, the energy efficiency was the highest.

    Analysis of gas generation performance and key microorganisms of high solid anaerobic digestion of straw mixed with pig manure
    Guozhi FU, Wenyang GUO, Zonghu MA, Wei LIU, Bokai LI, Ziyan SUN, Zhenxin WANG, Yeqing LI
    2020, 39(8):  3386-3394.  doi:10.16085/j.issn.1000-6613.2019-1311
    Abstract ( 276 )   HTML ( 1)   PDF (3329KB) ( 96 )  
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    A single raw material, such as crop straw or livestock manure, is subjected to anaerobic digestion, and the gas production is not satisfactory. Based on energy conservation and efficiency, two raw materials were mixed to study the effect of different mass ratios of straw and pig manure(2∶1, 1∶1 and 1∶2)on anaerobic digestion. The results showed that the ratio of raw materials had a significant effect on the gas production of anaerobic digestion. Among the three ratios, when the ratio of straw to pig manure was 2∶1, the cumulative biogas production was the largest, reaching 229.66L, and the final methane content was stable at about 60.71%, which meant the amount of methane produced per unit VS was 131.8mL/g VS. At the same time, the change of biogas liquid properties (pH, VFA, TIC) from the reaction process also indicated that when the ratio of straw to pig manure was 2∶1, the experiment ran smoothly and the gas production was better. In addition, microbiological analysis showed that in the experimental group with the ratio of 2∶1, the relative abundance of Methanosarcinaceae was higher during the first three weeks of the experiment, and the richness and diversity of bacteria and archaea communities were higher than other two groups.

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