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Table of Content
15 April 2024, Volume 43 Issue 4
    Perspective
    Prospects for the creation of novel interfacial separation materials driven by artificial intelligence
    HE Lin, HE Changqing, SUI Hong
    2024, 43(4):  1649-1654.  doi:10.16085/j.issn.1000-6613.2024-0175
    Abstract ( 57 )   HTML ( 5)   PDF (2394KB) ( 46 )  
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    The advancement of computer technology and artificial intelligence has presented a novel research paradigm, known as the "fourth generation". It has revolutionized the field of material development. Moreover, it has generated fresh prospects for the fabrication of interfacial separation materials. However, artificial intelligence is still in its infancy in this field. This is mainly ascribed to the constraints imposed by the interfacial separation process mechanism and the physical and chemical characteristics of materials and groups. This work developed a million-level (106) model database to address the issue of data scarcity in particular systems. The database furnished a substantial, dependable and standardized data foundation for generative models and large prediction models. Through extracting latent correlations between molecular properties and structures from large datasets and applying molecular simulation calculations to study the mechanism of inter-molecular interactions, the aim was to examine the governing laws of the recombination process. This enabled the development of interfacial separation materials with exceptional performance. Finally, this work concluded with a concise overview of the significant impact and prospects for growth that arose from interdisciplinary approaches, including meso-scale big data, machine learning potential theory, domestic software development, organic synthesis and intelligent algorithms. The intention was to facilitate the advancement of virtual laboratories to the forefront of innovation.

    Chemical processes and equipment
    Air gap membrane distillation research status and applications
    DU Yongliang, LIANG Zhuobin, GONG Yaoxu, BI Haojie, XU Zhiyuan, YUAN Hongying
    2024, 43(4):  1655-1666.  doi:10.16085/j.issn.1000-6613.2023-0715
    Abstract ( 41 )   HTML ( 2)   PDF (1761KB) ( 36 )  
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    As a new separation technology with excellent separation performance and energy saving potential, membrane distillation has attracted much attention under the background of the low-carbon economy. As a form of the membrane distillation with high thermal efficiency, air gap membrane distillation has more significant energy saving advantages. This paper summarized the domestic and international research progress related to air-gap membrane distillation, and the main research directions of membrane distillation technology were pointed out from the mass and heat transfer model, numerical simulation and membrane module structure. The current status of research and technology application for membrane distillation process optimization was highlighted. Membrane distillation process optimization included improving membrane flux or reducing membrane contamination through membrane module structural design optimization, the use of modified membranes, and the application of physical fields. In terms of technology application, air-gap membrane distillation technology could be applied mainly in the fields of seawater desalination, high concentration industrial wastewater treatment and concentration processing.

    Convection heat transfer research of supercritical R134a in mini-channel of tube
    ZHANG Qiaoling, MA Zuhao, YU Ziyuan, LIU Zijun, HUANG Biyun, YANG Zhendong, MA Haoran
    2024, 43(4):  1667-1675.  doi:10.16085/j.issn.1000-6613.2023-1273
    Abstract ( 30 )   HTML ( 0)   PDF (4999KB) ( 20 )  
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    The supercritical organic Rankine cycle (SORC) is an ideal new power cycle technology for recovering energy using supercritical organic Rankine cycle. The energy efficiency of the system is significantly affected by the SORC, the supercritical organic working medium, low grade energy recovery, and the heat transfer characteristics of the supercritical organic working medium. At present, it has become a bottleneck that restrict the development of organic Rankine cycle technology. To address this issue, the experimental studies were conducted on the flow heat transfer characteristics of supercritical R134a in a tiny channel with an inner diameter of 2mm). The parameters considered in the study were as follows: heat flux ranging from 60—120kW/(m2·s), mass flow rate from 800—3000kg/(m2·s), pressure from 4.1—5.1MPa, and working medium inlet temperature from 20—100℃. The effects of heat flow density, mass flow velocity, pressure and fluid temperature on the heat transfer characteristics were discussed. The results showed that the heat transfer coefficient initially increased and then decreased with the increase of fluid temperature. It also increased with the increase of mass flow rate but decreased with the increase of heat flux and pressure. According to the experimental data, a prediction accuracy of ± 10% for R134a in the microchannel was achieved, demonstrating good prediction accuracy.

    Numerical simulation plate side flow heat transfer new plate-shell heat exchanger with considering physical property changes and shell heat transfer
    SUN Chao, AI Shiqin, LIU Yuechan
    2024, 43(4):  1676-1689.  doi:10.16085/j.issn.1000-6613.2023-0890
    Abstract ( 31 )   HTML ( 0)   PDF (10852KB) ( 23 )  
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    With superior heat transfer performance and temperature and pressure resistance, plate-shell heat exchangers have broad application prospects in chemical production and other fields. Utilizing the realizable kε turbulence model combined with the enhanced wall function, a numerical simulation study was carried out on the plate side flow and heat transfer characteristics of a new type of plate-shell heat exchanger. The change of medium physical properties with temperature and the influence of shell heat transfer on heat transfer performance were discussed, and the fitting correlation formula obtained from existing experiments was verified. The flow and heat transfer characteristics of different corrugation heights at different inlet flow velocities were analyzed emphatically. At the same time, based on the field synergy principle, the synergy between the velocity field and the temperature field, and the field synergy angle distribution of the velocity field and the pressure field were revealed. The results showed that the flow and heat transfer of the heat exchanger couldnot ignore the influence of the change of the fluid medium‍’‍s physical properties and the heat transfer of the shell. With increased corrugation’‍s inclination height, the fluid flow line changed from “longitudinal flow” to “crossflow”. The distribution tended to be uniform and the heat transfer performance was improved. Continuous vortex structures were formed along the crests and troughs, and a periodic, centrally symmetrical high-shear vorticity concentration zone was formed around the contact point. The local field perpendicular to the flow direction synergistically presented a periodic variation, and the higher the corrugation height, the more pronounced the periodicity. Although the field synergy performance increased with the increase of the corrugation height, the fluid flow state changed with the increase of the flow velocity, and the flow in the core area of the corrugated channel was similar to the heat flow, which made the degree of synergy worse.

    Analysis on heat transfer characteristics of supercritical methane in precooling channels
    WANG Yanhong, JIANG Lei, XUE Shuai, LI Hongwei, JIA Yuting
    2024, 43(4):  1690-1699.  doi:10.16085/j.issn.1000-6613.2023-0657
    Abstract ( 27 )   HTML ( 0)   PDF (5472KB) ( 7 )  
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    In order to study the precooling performance of methane precooler, numerical research on heat transfer characteristics of supercritical methane in precooling channels were carried out based on Realizable k-ε turbulence model. Influence mechanisms of methane pressure and precooler structural parameter on heat transfer were analyzed. Temperature field and flow field characteristics in the channel section were discussed, the effects of centrifugal force and secondary flow on heat transfer were explored, and the entropy generation in the heat transfer process was analyzed. The influence of thermal acceleration on heat transfer was investigated, and a new dimensionless factor and criterion for thermal acceleration were proposed. The heat transfer correlation was established by combining the centrifugal force term and the thermal acceleration term. The results show that the low thermal conductivity of thermal boundary layer in the inlet region causes the heat transfer deterioration, and the centrifugal force leads to the circumferential difference in heat transfer. The strong secondary flow appears in the channel cross-section, and the heat transfer entropy generation is significant. The increase in methane pressure is beneficial for suppressing the heat transfer deterioration and weakening the effect of centrifugal force. The increase in outer diameter of precooler will enhance the centrifugal force and exacerbate the heat transfer deterioration. When Ac exceeds 8.19×10-7, the thermal acceleration plays a role in the deterioration of heat transfer. The proposed heat transfer correlation can effectively predict the heat transfer of supercritical methane in precooled channels.

    Numerical simulation of centrifugal spray drying based on single-droplet evaporation
    ZHU Yanni, WANG Wei, SUN Yanchenhao, WEI Gang, ZHANG Dawei
    2024, 43(4):  1700-1710.  doi:10.16085/j.issn.1000-6613.2023-0656
    Abstract ( 23 )   HTML ( 0)   PDF (5553KB) ( 10 )  
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    In order to analyze the physical field distribution and droplet movement pattern inside centrifugal spray dryer, a three-dimensional steady-state mathematical model of the spray drying process was established by using the Euler-Lagrange method coupling the single-droplet drying model. Experiments were conducted on a pilot-scale centrifugal spray drying system using 70% (wet basis) maltodextrin solution as the feedstock, and the temperature distribution inside the dryer was measured. The results showed that the simulated temperatures at characteristic points agreed well with the experimental values with 1.84% of average relative error, demonstrating the accuracy and reliability of the simulation results. Examination of continuous phase transfer process revealed that the three-dimensional physical field showed a cylindrically asymmetric distribution, having higher temperatures, lower water vapor contents, and greater airflow velocities at the center area of the tower. Analysis of droplet movement trajectory and drying process found that larger droplets had longer drying times, while smaller droplets had shorter drying times but longer residual time due to the occurrence of swirling and backflow. The effects of inlet air temperature, atomization disc rotation speed, and inlet air angle on the physical field distribution and droplet drying behavior inside the tower were studied by simulation, and the mass and heat transfer mechanism of spray drying process were analyzed.

    Experimental and numerical simulation on heat transfer characteristics of vertical cesium heat pipes
    ZHAO Jilong, GUO Yuxiang, CHEN Hongxia, YUAN Dazhong, DU Xiaoze
    2024, 43(4):  1711-1719.  doi:10.16085/j.issn.1000-6613.2023-0622
    Abstract ( 18 )   HTML ( 0)   PDF (3125KB) ( 7 )  
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    Medium-temperature cesium heat pipes’ expensive cost and the active chemical properties of cesium medium, lead to a big difficulty for experimental study. Thus, it is of great significance to analyze and predict the start-up characteristics and internal phase-change heat transfer of the cesium heat pipe by numerical simulation. Firstly, the frozen start-up experiment of a vertical cesium heat pipe was carried out, and based on current heat pipe simulation models, an adaptive model with consideration of the linkage of evaporator and condenser was established by UDF. As proved, the maximum temperature difference of the heat pipe wall between the experimental and the numerical simulation result was less than 20K, and the sudden temperature drop at the end of the condenser was present realistically, which proved the accuracy of the model. Secondly, based on the frozen start-up experiment of a vertical cesium heat pipe with variable heating power, the evolution of wall temperature and internal phase distribution of the heat pipe during the start-up process was simulated, and the average difference of wall temperature was used to evaluate the temperature uniformity over the effective length. At last, with various evaporator lengths (200mm and 120mm), heating powers (1028.2W and 844.4W) and filling ratios (8.8%, 12% and 15%), the phase distribution, temperature distribution and pressure distribution were compared and analyzed in simulation. The optimum matching condition of the evaporator length and the filling ratio was obtained by considering of the effective working length, temperature uniformity, condensate stacking and dry-out phenomena in the evaporator. The content had great potential significance for the optimal design of heat pipes.

    Technological conditions and optimization of near-critical water treatment of waste tobacco leaves
    LIU Zhaoyang, JIA Guotao, ZHU Zhizhong, YIN Quanyu, FU Hongzhe, ZHAO Xiangyu, LI Dingjun, YANG Xinling, ZHANG Mingyue
    2024, 43(4):  1720-1730.  doi:10.16085/j.issn.1000-6613.2023-0504
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    In order to explore the optimal process conditions for producing bio-oil from waste tobacco leaves treated with near-critical water, a single factor experimental design was used to investigate the effects of reaction temperature, solid-liquid ratio and holding time on the bio-oil yield of tobacco leaves. The technology conditions of near-critical water treatment of waste tobacco were optimized by orthogonal experiment. The results showed that the optimal treatment combination was 260℃, solid-liquid ratio 4∶50 and holding time 15min. Under these conditions, the yield of tobacco leaf bio-oil was 57.68%. The composition of water-soluble oil and residual oil was characterized by GC-MS analysis. The results showed that a total of 69 chemical components were isolated under the optimal extraction process conditions, mainly phenols, accounting for 49.39% of the total, followed by heterocycles, accounting for 25.69% of the total; a total of 37 chemical components were isolated from the residual oil, mainly esters and heterocycles, accounting for 25.66% and 20.21% of the total oil, respectively. This method follows the concept of green extraction, uses water as solvent, and is environmentally friendly. Compared with traditional extraction methods, this method has high yield of bio-oil and rich aroma components, which provides a new way for the treatment of waste tobacco leaves.

    Energy processes and technology
    Recent research and prospect of liquid organic hydrogen carries technology
    LIU Ruolu, TANG Haibo, HE Feifei, LUO Fengying, WANG Jinge, YANG Na, LI Hongwei, ZHANG Ruiming
    2024, 43(4):  1731-1741.  doi:10.16085/j.issn.1000-6613.2023-0515
    Abstract ( 42 )   HTML ( 2)   PDF (1594KB) ( 46 )  
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    As the vision of building a green hydrogen society, the demand for hydrogen energy will grow massively on a large scale as well, but the storage and transportation will also be the bottleneck that restricts the scale of the industrial development. Liquid organic hydrogen carries (LOHCs) have advantages over conventional high-pressure hydrogen storage methods in terms of low cost and safety for the large-scale storage and long-distance transportation of hydrogen energy. However, this technology is still at the early stage of development, and the related reports are limited. This paper reviews the main liquid organic hydrogen materials, aromatic such as aromatic hydrocarbons and aza-aromatic hydrocarbons, and analyses their hydrogen storage properties, advantages, problems and development status. Furthermore, various metal catalysts involved in hydrogenation and dehydrogenation processes are described. Finally, based on the current research, the prospects for liquid organic hydrogen storage technology are presented and the feasibility of liquid organic hydrogen storage technology in various fields and its high economic values are pointed out. However, for large-scale application, it's necessary to select the optimal liquid organic hydrogen materials, develop new catalysts with high selectivity, high catalytic activity and low cost, and further optimize hydrogenation and dehydrogenation technologies.

    Optimization of the preparation process of 52# Fischer-Tropsch wax based on DFSS method
    JIANG Chenguang, ZHANG Shengzhen, ZHANG Cuiqing, GUO Yi, SUN Yongwei
    2024, 43(4):  1742-1753.  doi:10.16085/j.issn.1000-6613.2023-0706
    Abstract ( 16 )   HTML ( 1)   PDF (5661KB) ( 3 )  
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    52# Fischer-Tropsch wax was prepared by solvent extraction from hydrorefining reduced third-line oil, which was investigated based on the six sigma design. The mathematical models of the oil content, yield, melting point and solvent-oil ratio, solvent ratio, crystallization time, cooling rate, and crystallization temperature were proposed by using the central composite design assigned to response surface design, analyzing the influence of each factor and their interaction on the response value. The optimal combination of preparation process parameters and better operation window were obtained by multi-objective optimizing, which guided the 100kg/h pilot test to proceed smoothly. The results showed that when the solvent-oil ratio was 5, solvent ratio was 2, crystallization time was 6min, crystallization temperature was 5℃, and the cooling rate was 5.3℃/min, the melting point of the wax was 52—54℃, the oil content was 0.2%—0.8%, and the yield was more than 25%, which met the requirement of the refined wax. The experimental value was closed to the predicted value of the model, which indicated that the models had good fitting effect, high prediction accuracy and reliable quality.

    Start-up characteristics of high-temperature proton exchange membrane fuel cell stacks based on flat heat pipes
    QIAN Zhiguang, WANG Shixue, ZHU Yu, YUE Like
    2024, 43(4):  1754-1763.  doi:10.16085/j.issn.1000-6613.2023-0714
    Abstract ( 10 )   HTML ( 0)   PDF (4387KB) ( 7 )  
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    High-temperature proton exchange membrane fuel cells (HT-PEMFC) operate at about 160℃ and have the advantages of better electrochemical reaction kinetics, simpler hydrothermal management and higher CO tolerance than conventional low-temperature cells. However, upon the increase of operating temperature, the fast start-up of HT-PEMFC becomes one of the important challenges that restrict its application promotion. In current work, a preheat start-up method using a flat plate heat pipe (FHP) for a HT-PEMFC reactor with a rated power of 500W was attempted. An experimental system was designed and built to evaluate this method in terms of preheating time, temperature distribution, and heat transfer distribution. The experimental results showed that increasing the heating power significantly reduced the preheating time from 3000s at 500W to 980s at 1500W. However, it also caused a deterioration of the temperature uniformity, with a maximum temperature difference of about 28℃ in the vertical direction at 500W increased to 80℃ at 1500W. In addition, the temperature difference in the horizontal direction increased with the heating power, especially in the area close to the heat source, up to 15.7℃, which would undoubtedly accelerate the mechanical failure of the proton exchange membrane. In practice, a higher heating power should be selected to reduce the start-up time but not affecting the cell operating life too much.

    Evaluation of the thermal energy storage performance of calcium-magnesium binary composite salt hydrates
    LIU Han, QU Minglu, YE Zhendong, YANG Fan, HUANG Beijia, ZHANG Yaning, LIU Hongzhi
    2024, 43(4):  1764-1773.  doi:10.16085/j.issn.1000-6613.2023-0648
    Abstract ( 32 )   HTML ( 4)   PDF (6199KB) ( 8 )  
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    Salt hydrate as a type of thermochemical energy storage materials involves reversible chemical reactions for the storage and release of heat during the processes of adsorption and desorption. It has high thermal energy storage density and is suitable for long-term thermal energy storage. Moreover, it can be combined with solar energy utilization, which can reduce the dependence on fossil energy. In this study, effect of different porous matrix, microporous molecular sieve(13X) and mesoporous diatomaceous earth(WSS) on the thermal energy storage performance of calcium-magnesium binary composite salt hydrates was investigated based on MgCl2 and CaCl2 with a molar ratio of 1∶2. Firstly, the pore structure, sorption isotherm and cycle stability of the developed two types of calcium-magnesium binary composite salt hydrates were compared. A two-dimensional model of a honeycomb thermal energy storage unit was used to analyze the storage/release performances of the developed two composites. Results showed that the 13X had smaller pore volume, larger specific surface area than WSS. Due to the impregnation of MgCl2/2CaCl2, the pore volume, specific surface area and porosity of calcium-magnesium binary composite salt hydrates had been reduced compared to those of corresponding porous matrix. Both MgCl2/2CaCl2 composites showed higher sorption capacity than that of the porous matrix. Moreover, the Polanyi adsorption potential theory could describe the sorption isotherm of the calcium-magnesium binary composite salt hydrates well. Furthermore, the simulation results showed that the thermal energy storage density of the WSS20 was 371.94MJ/m3, which was higher than that of 13X17, as well as the energy released power and recovery efficiency. The WSS20 could be used for storing/releasing thermal energy more than 47 times, while the 13X17 showed bad stability even within 10 cycles. Therefore, considering both thermal energy storage density and cycle stability, WSS20 was more suitable for storing thermal energy.

    Effect of non-uniform electric field on bubble dispersion characteristics in high-viscosity fluid
    HE Fachao, LIU Hailong, LI Changfeng, WANG Junfeng
    2024, 43(4):  1774-1782.  doi:10.16085/j.issn.1000-6613.2023-0582
    Abstract ( 14 )   HTML ( 1)   PDF (4612KB) ( 7 )  
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    Electric field enhanced multiphase flow technology for interphase dispersion and mass transfer is widely used in chemical production. The size and dispersion behavior of bubbles and the physical properties of the continuous phase are important factors affecting the mass transfer efficiency in multiphase flow systems. In this study, a charged liquid-gas dispersion experimental platform was designed and built to visually study the dispersion behavior of bubbles in a high-viscosity fluid under the action of a non-uniform electric field. The morphological characteristics of the bubbles during the growth and dispersion process were recorded, and the effects of electric field strength and gas flow rate on the bubble dispersion behavior and bubble size were analyzed. The experimental results indicated that with the increase of electric field intensity, the dispersion behavior of air in glycerol underwent transitions from dripping mode to bead mode when the electric Bond number (BoE) reached 4.5. After reaching 8.7, it further transformed into mixed mode and finally corona mode when the electric Bond number reached 17.8. The bubble diameter decreased significantly with increasing electric field strength. Compared to the bubble size under no electric field, the bubble diameter decreased by 80% when the electric Bond number reached 6.4. In the mixed mode, the bubbles broke into numerous microbubbles, with microbubble diameters below 100μm. This effectively increased the interface area between the gas and liquid phases. Meanwhile, the study showed that the transition of the bubble dispersion mode mainly depended on the electric field strength, and the increase of the gas flow rate had little effect on the transition of the bubble dispersion mode and the bubble diameter. Based on the existing data, bubble diameter prediction model related to the electric Bond number in the range 0<BoE<16 was established. The results of this study could provide reference for the growth and dispersion behavior of bubbles in complex fluids under the action of electric fields.

    Industrial catalysis
    Research progress in synergistic catalytic elimination of multiple pollutants in flue gas of coal combustion coupled with renewable fuels
    WANG Hongyan, MA Ziran, LI Ge, MA Jing, ZHAO Chunlin, ZHOU Jiali, WANG Lei, PENG Shengpan
    2024, 43(4):  1783-1795.  doi:10.16085/j.issn.1000-6613.2023-0535
    Abstract ( 16 )   HTML ( 0)   PDF (3818KB) ( 12 )  
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    Aiming at the problems of synergistic catalytic elimination of multiple pollutants (NO, Hg0, VOC, etc.) in the flue gas of coal combustion coupled with renewable fuels under the background of "dual carbon", we summarized the single component and multi pollutant synergistic catalytic elimination mechanism, interaction mechanism and catalyst design in this work. The mechanism of synergistic catalytic elimination of multiple pollutant is similar to that of single pollutant removal, but the performance of synergistic elimination is affected by interaction of pollutants and flue gas composition. The active components, heterogeneous reaction processes, and monolithic catalyst were reviewed. Finally, the prospect of synergistic catalytic elimination of multiple pollutants in flue gas of coal combustion coupled with renewable fuels is proposed that includes the catalyst optimization at the molecular and mesoscopic levels, high stability dispersion of active components, breaking the adsorption mode, design of anti-poisoning catalyst and systematic research in practical application.

    Preparation of PEMFC catalysts by electrodeposition
    CHEN Jiayi, GAO Weitao, YIN Yanan, WANG Cheng, OUYANG Hongwu, MAO Zongqiang
    2024, 43(4):  1796-1809.  doi:10.16085/j.issn.1000-6613.2023-0695
    Abstract ( 21 )   HTML ( 0)   PDF (16975KB) ( 13 )  
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    As an energy conversion device that converts fuel chemical energy directly into electrical energy, proton exchange membrane fuel cell (PEMFC) has received much attention because of its high efficiency and environmental protection advantages. The catalyst directly determines the performance of PEMFC and is one of the most central parts of PEMFC. Electrodeposition is considered as a promising method for the preparation of PEMFC catalysts due to the advantages of controllable nucleation, low cost, easy operation and scalability. This article introduces the common processes in electrodeposition and reviews the representative achievements of PEMFC catalyst preparations by electrodeposition in recent years. It is pointed out that through accurately controlling the voltage, current and solution components, the electrodeposition has outstanding advantages in the preparation of alloy catalysts, non-precious metal catalysts, and catalysts with special morphologies such as core-shell structure, nanowire structure and nano-array structure. This allows the electrodeposition superior to other methods for the preparation of PEMFC catalysts, and to achieve industrial application. Finally, this article foresees the future research focus and direction for the preparation of PEMFC catalysts by electrodeposition, and points out that the researches on the regulation mechanism and catalytic mechanism of electrodeposition should be combined to guide the improvement of the preparation process. Meanwhile, the application pathway of electrodeposition for low-platinum or non-platinum catalysts should be explored, which will be of help to the technological breakthrough of PEMFC catalysts.

    Particulate photocatalysts for light-driven overall water splitting
    WU Chenhe, LIU Yumin, YANG Xinmin, CUI Jiwei, JIANG Shaokun, YE Jinhua, LIU Lequan
    2024, 43(4):  1810-1822.  doi:10.16085/j.issn.1000-6613.2023-0603
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    Photocatalytic overall water splitting (POWS) is a simple and cost-effective approach to directly transforming solar energy into green hydrogen, which attracts great attention and demonstrates a bright prospect. The performance of photocatalyst is recognized as the key factor in the development of POWS. The strategies for improving the performance mainly focus on the three fundamental steps of photocatalysis, i.e., light absorption, carrier separation and migration and surface reaction. This paper reviews the recent achievements from the perspectives of valid strategies in coping with the challenges in these steps. Based on this, we summarize the important strategies of designing and preparing efficient photocatalysts for POWS and analyze the remaining obstacles to the industrial application of POWS. It is pointed out that the main challenge at present is to develop efficient narrow-gap photocatalysts. Meanwhile, the problems of serious backward reaction, the instability of the materials, and the technological problems like the separation of H2-O2 mixture during large-scale operations should also be addressed in the future.

    Effect of precipitating agent on the performance of Co3O4-catalyzed decomposition of N2O
    SUN Jinru, SONG Aolei, ZHAO Mingxin, ZHAO Tiantian, WANG Hong, KE Ming
    2024, 43(4):  1823-1831.  doi:10.16085/j.issn.1000-6613.2023-0579
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    The Co3O4 composite metal oxides were prepared by the hydrothermal method using cobalt acetate as the cobalt source. The physicochemical properties of the catalysts were characterized by XRD, FTIR, TEM, SEM, BET, H2-TPR, O2-TPD and XPS. The catalyst catalytic decomposition activity of N2O was evaluated in a fixed-bed microreactor, and the effect of precipitants (NaOH、 Na2CO3、 NaHCO3、 H2NCONH2、 CH8N2O3、 NH3·H2O) on the catalytic decomposition performance of N2O was investigated. The results showed that the Co3O4 catalysts prepared by the hydrothermal method were all of spinel structure, and different precipitating agents affected the catalyst morphology, redox performance and catalytic decomposition N2O activity. The activity of the catalysts prepared with sodium precipitant was higher than that of other catalysts because it promoted the reduction process of Co3+ to Co2+, influenced the chemical environment of cobalt ions, improved the electron donating capability, weakened the Co—O bond in the catalyst, and accelerated the regeneration of oxygen vacancies during the catalytic reaction. The Co3O4-NaOH catalyst, which contained a small amount of Na ions, had a strong redox ability, a large Oads/Olatt ratio, resulting in a large amount of oxygen adsorbed on the surface, and a low N2O decomposition temperature. Under the conditions of the reaction gas composition of 0.88% O2, 0.65% N2O, and N2 as equilibrium gas (flow rate of 80mL/min), T10 and T95 were 330℃ and 470℃, respectively.

    Regulation of catalyst acid sites and its effect on the deep hydrogenation performance of anthracene
    LIU Yurong, WANG Xingbao, LI Wenying
    2024, 43(4):  1832-1839.  doi:10.16085/j.issn.1000-6613.2023-0529
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    Deep hydrogenation of polycyclic aromatic hydrocarbons (PAHs) in coal tar is an effective method to prepare coal-based high energy density fuel. Due to the unique electronic structure and steric hindrance effect, present catalysts show insufficient capacity for deep hydrogenation of PAHs. In addition, increasing the acidity of catalyst and reaction conditions will lead to the increase of cracking products and the decrease of selectivity of perhydro-products. In this study, Al-SBA15 and USY were used to prepare composite meso-microporous supports with moderate acidity by hydrothermal synthesis. The noble metal Pt was loaded on the composite acid support by equi-volume impregnation. The saturation hydrogenation performance of the synthesized composite catalyst for the model compound anthracene was studied. The results showed that the selectivity of perhydroanthracene could reach about 99% when Brønsted acid content was 144.4μmol/g. TEM and SEM results showed that the Pt/Al-SBA15+USY catalyst was rod-like after hydrothermal recombination with USY inside and Al-SBA15 outside. The composite support maintained the original pore size of about 9.6nm and 0.8nm, respectively. Pt nanoparticles had high dispersion and the optimal size was 3.03nm. Comparative analysis showed that the acid content of the composite support prepared by hydrothermal synthesis of Al-SBA15 and USY molecular sieve was lower than that of the molecular sieve support after direct mixing. Thus, the capacity of saturated hydrogenation was improved.

    Effect of oxygen vacancies in Ni/Sm2O3-CeO2/Al2O3 catalyst on CO2 methanation at low temperature
    GUO Xiaodong, MAO Yujiao, LIU Xiangyang, QIU Li, YU Feng, YAN Xiaoliang
    2024, 43(4):  1840-1850.  doi:10.16085/j.issn.1000-6613.2023-0571
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    Ni/Sm2O3-CeO2/Al2O3 and Ni/MnO x -Sm2O3-CeO2/Al2O3 catalysts were obtained by using Mn, Sm and Ce sources in the form of LDHs precursor by hydrothermal synthesis after a standard calcination and reduction treatment. Subsequently, the catalytic performance of the two catalysts were investigated at low temperature in CO2 methanation. Compared to Ni/Sm2O3-CeO2/Al2O3, Ni/MnO x -Sm2O3-CeO2/Al2O3 with the introduction of MnO x showed an excellent performance below 225℃, with 68% of CO2 conversion and 100% of CH4 selectivity, and 0.087s-1 of TOF, which was higher than that of Ni/Sm2O3-CeO2/Al2O3 (0.013s-1). Meanwhile, Ni/MnO x -Sm2O3-CeO2/Al2O3 maintained stable CO2 conversion and CH4 selectivity in long-term test for 100h. This was mainly due to the fact that the introduction of MnO x increased the oxygen vacancies on Ni/MnO x -Sm2O3-CeO2/Al2O3 with a high degree of Ni particle dispersion. Meanwhile, MnO x could also increase the basic sites of the resultant catalyst, which promoted CO2 adsorption and activation. In situ DRIFTS analysis further revealed that oxygen vacancies on Ni/MnO x -Sm2O3-CeO2/Al2O3 promoted the formation of formate and methoxy intermediates at low temperatures, leading to an enhanced catalytic properties in CO2 methanation.

    Vermiculite-supported FeCe bimetallic catalyst for selective catalytic reduction of NO with CO
    GAO Fei, LIU Zhisong, PAN Keke, LIU Minmin, DAI Bin, DAN Jianming, YU Feng
    2024, 43(4):  1851-1862.  doi:10.16085/j.issn.1000-6613.2023-0525
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    NO removal by CO selective catalytic reduction (CO-SCR) has gained great attentions. In this paper, vermiculite-supported Fe-Ce bimetallic oxides (FeCe/VMT) for CO-SCR were prepared by coprecipitation-assisted impregnation (CP-IM) with the natural mineral vermiculite as the carrier. The characterization results showed that compared with the traditional impregnation method (IM), FeCe/VMT (CP-IM) prepared by coprecipitation-assisted impregnation had larger specific surface area (106.9m2/g) and more oxygen vacancies due to more active sites available. The enhanced synergistic effect between FeCe was beneficial to the increase of both catalytic activity and stability in CO-SCR reaction. Performance tests showed that NO conversion reached 100% at 300℃ with 50000h-1 gas hourly space velocity (GHSV), and the performance of the catalyst didn't decrease within 48h. When the temperature dropped to 250℃, the conversion of NO could still reach 97%. At the same time, insitu infrared spectroscopy and density functional theory were used to reveal the corresponding catalytic mechanism. This research provided a promising method for preparing supported catalysts with large specific surface area.

    Materials science and technology
    Advances in adsorbents for aromatics/cycloalkanes separation
    JIN Binhao, ZHU Xiaoqian, KE Tian, ZHANG Zhiguo, BAO Zongbi, REN Qilong, SU Baogen, YANG Qiwei
    2024, 43(4):  1863-1881.  doi:10.16085/j.issn.1000-6613.2023-0533
    Abstract ( 26 )   HTML ( 3)   PDF (14462KB) ( 24 )  
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    Due to its energy efficiency and environmental friendliness, adsorption has the potential to replace extractive distillation as a new method for the separation of aromatics/cycloalkanes with the same amount of carbon atoms. The materials used for adsorption separation have evolved from the traditional molecular sieves to new porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs) and porous molecular crystals (PMCs), which show preferential adsorption of aromatics or cycloalkanes and excellent selectivity. This review investigated the recent progress of MOFs, COFs and PMCs for the separation of benzene/cyclohexane and toluene/methylcyclohexane, focusing on the ideas of structural design, the adsorption and separation performance and mechanisms of the three types of materials. These mechanisms included two different types of mechanisms such as thermodynamic equilibrium and molecular exclusion. Though remarkable progress had been made, some prominent issues still existed in this field. The laws of diffusion and mass transfer of adsorbent as well as the separation performance of materials loaded in fixed bed for mixtures were inadequately researched, the stability and impurity sensitivity of materials were not caught enough attention, the structures of porous materials were overly complex, and the costs of materials needed to be reduced. All of them needed to be taken into account in future research.

    Progress in the preparation of hierarchically porous MOF and applications in adsorption and separation
    YANG Dongxiao, XIONG Qizhao, WANG Yi, CHEN Yang, LI Libo, LI Jinping
    2024, 43(4):  1882-1896.  doi:10.16085/j.issn.1000-6613.2023-0546
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    Metal-organic framework (MOF), which has the advantages of high specific surface area, abundant porosity and adjustable pore size, has received attention from many scholars and is considered as an ideal adsorbent for adsorption and separation. However, in practical applications, most microporous MOF materials are severely limited in their intrinsic mass transfer rates during adsorption, and methods for constructing hierarchically pores are not universally applicable. In this paper, the methods for constructing hierarchical pores MOF such as moderator strategy, template strategy and post-processing strategy were introduced. The hierarchically pores materials with both mesopores and macropores were prepared, and the advantages and disadvantages of each method with application scenarios to obtain a universal strategy for constructing hierarchical pores MOF with adjustable pore size under relatively mild conditions were evaluated. To address the application of hierarchically porous MOF materials in the field of gas adsorption and separation, this paper focused on the case of constructing hierarchical pores MOF to enhance the adsorption of CO2 gas. It was found that the construction of hierarchically porous increased the pore size, improved the specific surface area of MOF, and provided additional pore channels to enhance the adsorption capacity and mass transfer rate of gas molecules. The results showed that the hierarchically pores MOF had excellent performance in gas adsorption and separation. Finally, the problems of hierarchical pores MOF synthesis and application were discussed, and the challenges faced by hierarchical pores MOF such as green reproducibility of the synthesis process were prospected.

    Research progress on polymeric membranes containing fluorenyl, imide and naphthyl groups for gas separation
    FAN Wenxuan, XU Shuangping, JIA Hongge, ZHANG Mingyu, QU Yanqing
    2024, 43(4):  1897-1911.  doi:10.16085/j.issn.1000-6613.2023-0661
    Abstract ( 18 )   HTML ( 1)   PDF (6413KB) ( 8 )  
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    The inter-polymer chain spacing and polymer chain stiffness are the determining factors for gas permeation properties, the introduction of rigid groups (fluorenyl, imide and naphthyl) into the polymer chain can effectively improve gas permselectivity due to the presence of large volume and rigid twisted groups in polymers can inhibit interchain stacking of relatively rigid chains (i.e., increase free volume fraction) and reduce rotational mobility around flexible links (i.e., increase stiffness). In this paper, the recent five years studies on membranes based on polymer containing fluorenyl, imide and naphthyl group materials in the field of gas separation were reviewed. These researches were classified by the structure of polymer materials that make up the membranes and introduced in terms of synthesis, gas selectivity and the main factor affecting the selectivity. Finally, based on the characteristics of rigid polymers, the application of rigid polymer materials should be expanded in terms of the modification of existing materials with high gas permeability and low selectivity, the modification of bio-based materials and the preparation of composite membranes, providing a reference for the preparation of gas separation membranes with high performance in the future.

    Silica-based aerogel materials and their preparation technology from a patent analysis
    XIONG Wenting, LUO Qiji, YAN Chungen
    2024, 43(4):  1912-1922.  doi:10.16085/j.issn.1000-6613.2023-0673
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    Aerogel is a multifunctional new material. The silica-based aerogel as the most widely studied aerogel material, first industrialized in China in 2004, has been widely used in electronics, construction, thermal insulation, aerospace, energy and other fields. However, compared with foreign countries, there are fewer high-end products in China and the original innovation is slightly insufficient. In this paper, the patents related to silica-based aerogel materials and its preparation technology in the past 20 years were studied and the research hotspots in the past 20 years from the perspective of patents were explored. This paper analyzed the current market competition pattern from the dimensions of market flow and key applicants, and pointed out that the developed countries represented by the United States, Germany and Japan were in the leading position through the global patent layout to achieve a greater control of the market to a certain extent. It focused on analyzing the research hotspots of silica-based aerogel and its preparation technology from the perspectives of technical hotspots and technical routes. At present, aerogel particles, precursor improvement and fiber reinforcement were the research focuses in this field in recent years, and all countries had paid more attention to metal oxide composites and transparent energy storage materials. Then, by sorting out the technical characteristics of Chinese transferred and transformed patents, it helped enterprises to accurately find cooperation partners when seeking technical cooperation. Finally, the research directions that Chinese enterprises needed to focus on in technological innovation were summarized to provide guidelines for future technological research and development.

    Optimization of compounding ratio of fume-suppressing asphalt and evaluation of its effect of fume suppression
    LI Ping, CHEN Xiule, ZHANG Qiang, NIAN Tengfei, WANG Yuxing, WANG Meng
    2024, 43(4):  1923-1933.  doi:10.16085/j.issn.1000-6613.2023-0613
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    In order to suppress the generation of asphalt fumes at high temperatures and reduce the level of environmental pollution and the health impact of operators, the optimization study of the compounding ratio of fume-suppressing asphalt was carried out. Based on the needle penetration, ductility and softening point of single-doped fume-suppressing asphalt and the fume production test results of the asphalt under the self-research device, the optimization of the ratio of fume-suppressing asphalt was carried out by combining entropy weight method and genetic algorithm, and analysis of the dispersion uniformity and storage stability of the optimized fume suppressant in asphalt and its effect on the characteristic functional groups of asphalt. The high, medium and low temperature performance tests of fume-suppressing asphalt based on the optimized compounding ratio were carried out, and the effect of fume suppression was evaluated to verify the effectiveness of the optimized compounding ratio method. The main conclusions were as follows. The fume suppressant was uniformly dispersed in the asphalt and did not change the characteristic functional groups of asphalt. The optimized compounded fume-suppressing asphalt met the storage stability requirements. The optimized compounding of fume suppressant improved high and low temperature performance of asphalt and enhanced the medium temperature fatigue performance of asphalt. The color change of the filter tube before and after the asphalt fume collection indicated that the asphalt fume enrichment method was highly reliable. The optimized compounding fume-suppressing asphalt had a significant effect of fume suppression and the maximum fume suppression rate was 99.7%. The small difference between the predicted and measured values of the indicators proved the reliability of the optimized compounding ratio method.

    Preparation and sodium storage application of one-dimensional porous TiO2@carbon nanofibers composite
    HU Feiyan, PENG Jiahuan, LI Heng, XU Zhaohua, SUN Ning
    2024, 43(4):  1934-1943.  doi:10.16085/j.issn.1000-6613.2023-0615
    Abstract ( 9 )   HTML ( 0)   PDF (8175KB) ( 3 )  
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    One-dimensional porous titanium dioxide@carbon nanofibers (P-TiO2@CNFs) composite with a lamellar branch structure was prepared by in situ electrospinning and concentrated alkali hydrothermal etching methods, and then employed as the anode material of sodium-ion batteries. The lamellar branching structure could effectively shorten the ion diffusion pathway and increase the contact area between electrolyte and active material. The porous structure provided more reactive sites, thus accelerating the charge transfer kinetics. Finally, the chemical bonding between TiO2 and carbon nanofibers could reinforce the structural stability of the composites. The surface morphology, microstructure, crystal structure, specific surface area, pore size and valence state of P-TiO2@CNFs were analyzed. The galvanostatic charge and discharge measurements and rate performance tests were performed on the NEWARE battery test system. The experimental results demonstrated that P-TiO2@CNFs exhibited excellent reversible capacity of 197mAh/g at 2.0A/g after 2000 cycles, and high specific capability of 61.7mAh/g at an ultrahigh current density of 30.0A/g.

    Experimental study on the preparation and stability of water-based carbon black-collagen nanofluids
    LI Kai, WEI Helin, ZUO Xiahua, YANG Weimin, YAN Hua, AN Ying
    2024, 43(4):  1944-1952.  doi:10.16085/j.issn.1000-6613.2023-0561
    Abstract ( 13 )   HTML ( 1)   PDF (3144KB) ( 4 )  
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    Due to their excellent photothermal conversion performance, nanofluids have become the research focus of new solar collector media. However, due to its poor stability and complex preparation process, it has not been promoted in practical applications. In this paper, carbon black-collagen nanofluids were prepared by a two-step method using deionized water as the base solution. The effects of material addition order, collagen type, ultrasound time, material ratio and solution pH on the stability of nanofluids were explored. The results showed that the stability could be improved by dispersing carbon black and then adding collagen when preparing water-based carbon black-collagen nanofluids. Porcine skin collagen was more suitable for the preparation of carbon black-collagen nanofluids. The nanofluids prepared by ultrasound for 45min, the carbon black collagen mass ratio of 1/20 and the pH of suspension of 6.5―7.5 had good stability. This research would contribute to the industrial application of water-based carbon black-collagen nanofluids in the field of solar photothermal conversion in the future.

    Preparation and adsorption properties of zinc-doped titanium-based cesium ion sieves
    WANG Debin, LIN Mengyu, YANG Xue, DONG Dianquan
    2024, 43(4):  1953-1961.  doi:10.16085/j.issn.1000-6613.2023-0555
    Abstract ( 14 )   HTML ( 0)   PDF (4843KB) ( 9 )  
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    Titanium-based ion sieve adsorbents have good application prospects in the extraction of cesium from salt lake brine and the treatment of radioactive nuclear wastewater. In this paper, based on the improved sol-gel technology, trace Zn2+ was doped into the Ti—O lattice of Cs2Ti6O13 to improve the cell structure, and the zinc doped titanate precursor material (CZnTO) was prepared. The precursor was subjected to acid treatment to form a zinc-doped protonated titanate (HZnTO). The prepared HZnTO was characterized by XRD, SEM, EDS, FTIR, Raman spectroscopy and XPS, which showed that the incorporation of trace amounts of Zn2+ did not destroy the original layered structure. Through adsorption experiments, the effects of aqueous pH, initial cesium ion concentration, adsorption time and temperature on the adsorption behavior of HZnTO were investigated. The studies found that at 288K, pH=11 and an initial Cs+ concentration of 3000mg/L, the adsorption of HZnTO for about 2h could achieve a saturated adsorption capacity of 323mg/g. In a low concentration solution with an initial Cs+ concentration of 30mg/L, HZnTO could still maintain an adsorption and removal rate of over 80%. The adsorption of Cs+ on HZnTO conformed to the quasi second order kinetic equation and Langmuir adsorption isotherm, indicating that the adsorption of Cs+ on HZnTO was chemical adsorption mainly by single molecular layer adsorption. Selective adsorption experiments and cyclic adsorption-desorption experiments showed that the selectivity of HZnTO for Cs+ was much higher than that of other ions. After 7 cycles of cyclic adsorption, the adsorption capacity of HZnTO could still reach 87.6% of that of the initial cycle, demonstrating a good stability.

    Preparation and characterization of gel polybenzimidazole proton exchange membrane with alkyl sulfonic acid side chains
    ZHU Taizhong, ZHANG Liang, HUANG Zequan, LUO Lingping, HUANG Fei, XUE Lixin
    2024, 43(4):  1962-1971.  doi:10.16085/j.issn.1000-6613.2023-0636
    Abstract ( 12 )   HTML ( 0)   PDF (4277KB) ( 8 )  
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    Phosphoric acid (PA) doped polybenzimidazoles (PBI) has become a preferred material for high-temperature proton exchange membrane fuel cells (HT-PEMFCs) due to its excellent thermal and chemical stability, as well as its high glass transition temperature. However, the weak dissociation and diffusion rate of phosphoric acid molecules at low temperatures resulted in poor proton conductivity of the membrane and difficulties in cold start-up of the fuel cell. Therefore, developing high-temperature proton exchange membranes that can operate efficiently over a wide range of temperatures and humidities is currently a challenge. In particular, extending the low-temperature operating window and achieving cold start-up capability are of great significance for the practical applications of fuel cells, such as in vehicles. In this study, a series of PA doped gel state polybenzimidazole proton exchange membranes with flexible alkyl sulfonic acid side chains were designed and synthesized through a polyphosphoric acid sol-gel process and a lactone ring-opening reaction. The effects of introducing sulfonic acid and varying the side-chain length on PA doping level, proton conductivity, and stability under different temperatures and humidities were investigated. The results showed that the prepared gel state membranes had a porous structure with self-assembled layer stacking, which facilitated the absorption of a large amount of PA and provided fast pathways for proton transmission. Among them, PA/PS-PBI exhibited proton conductivity performance superior to other reported works over a wide temperature range. Specifically, at room temperature, its proton conductivity increased from 0.0286S/cm of the original membrane to 0.0694S/cm, which was further increased to 0.1619S/cm and 0.3578S/cm at 80℃ and 200℃, respectively. In addition, the proton conductivity values of these membranes below 80℃ under 0% relative humidity (RH) were comparable to those of Nafion membrane under 100% RH, providing a new solution for breaking the classic definition of proton exchange membranes and achieving for applications in wide temperature range (25—240℃) fuel cell operations.

    DES changed the diffusion rate of amine monomer to prepare high-performance composite reverse osmosis membrane
    HE Jin, LAI Yuwen, LI Yanchun, ZHOU Shilin, ZHOU Yong, GAO Congjie
    2024, 43(4):  1972-1980.  doi:10.16085/j.issn.1000-6613.2023-0713
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    Among the commonly used methods to improve the performance of composite films, interfacial polymerization (IP), a key step to regulate the formation of composite films, is a simple and effective method, however, the influence of deep eutectic solvents in the process of interfacial polymerization is relatively rare, and a polyamide composite reverse osmosis membrane is prepared by introducing deep eutectic solvents (DES with a molar ratio of 1∶2) into the interfacial polymerization process. The structure and physicochemical properties of composite films were characterized by Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effect of DES addition on the performance of reverse osmosis membrane was investigated, and the effect of viscosity on the diffusion rate of amine monomer was systematically analyzed. When the DES addition amount was 5%, the composite membrane had the best comprehensive performance, with a flux of 63L/(m2·h) and a retention rate of 99%. The results showed that the incorporation of DES reduced the surface roughness, hydrophilicity and electronegativity, and increased the flux of the composite reverse osmosis membrane modified by DES compared with the unmodified composite membrane. This work was of great significance for the preparation of high-performance composite membranes.

    Co-production and modification of magnesium hydroxide and calcium carbonate by controlled carbonization of dolomite
    PENG Lijia, WANG Yinlong, ZHAI Chen, WANG Qi, CHEN Xiaopeng, TONG Zhangfa
    2024, 43(4):  1981-1991.  doi:10.16085/j.issn.1000-6613.2023-0688
    Abstract ( 21 )   HTML ( 0)   PDF (4716KB) ( 8 )  
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    The comprehensive use of dolomite for the development of high-end products and their technologies have become the focus of current researchers. In this paper, high value-added magnesium hydroxide and calcium carbonate were prepared by controlled carbonation method of dolomite and modified. The effects of pH at the end-point, temperature and CO2 flow rate of carbonation on the crystalline and particle morphology of the products, as well as the effects of zinc stearate addition, stirring speed, time and temperature on the modification of the products were investigated respectively. The results showed that when the pH at the end-point of carbonation reaction was controlled to 10.5, the products contained only calcium carbonate and magnesium hydroxide; the optimal carbonation reaction conditions were 20℃ and CO2 flow rate 1L/min, and the average particle size of magnesium hydroxide and calcium carbonate was 190.4nm; the optimal modification conditions of magnesium hydroxide and calcium carbonate were zinc stearate addition 1.0%, stirring speed 600r/min, modification time 60min, and modification temperature 50℃ , the activation degree of the modified magnesium hydroxide and calcium carbonate was 95.8%, and the oil absorption value was 41.2g/100g.

    Synthesis and performance test of an acid and alkali resistant high strength resin
    WANG Bing, WANG Lei, HUANG Xinru, YUAN Hongpeng, LAI Xiaojuan, LI Peng
    2024, 43(4):  1992-2000.  doi:10.16085/j.issn.1000-6613.2023-0610
    Abstract ( 10 )   HTML ( 0)   PDF (2082KB) ( 12 )  
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    Secondary cementing of small casing is a new type of cementing technology. At present, due to the brittleness of cement itself, it is easy to gas channeling and water channeling, and it is an alkaline solidified body, which is easy to produce cracks under pressure, and it is also easy to be damaged by acidic medium. An unsaturated polyester resin was synthesized by using D-33 diol and maleic acid as raw materials and styrene as dispersant. The introduction of fillers in the resin system improved the toughness and compressive strength of the product. The resin was characterized by FTIR. The performance of the resin system was evaluated by universal testing machine. The results indicated that the target product contained the characteristic peaks of aldehyde group, carbon-carbon double bond and p-benzene ring structure. The curing system was dibenzoyl peroxide / N,N-dimethylaniline, and its dosage at 50℃, 60℃ and 70℃ was 0.2%/0.02%, 0.1%/0.02% and 0.1%/0.01%, respectively. The test results of universal testing machine showed that the compressive strength after curing at 50℃, 60℃ and 70℃ for 24h was about 50MPa, 70MPa and 90MPa, respectively. A cementing material with adjustable polymerization time, low viscosity, high pressure resistance, acid and alkali resistance was obtained in the experiment, which was expected to be widely used in horizontal well refracturing.

    Biochemical and pharmaceutical engineering
    Pseudo-protein biomaterials: Classification, synthesis and application
    XUE Yunjiao, ZHANG Xuan, LIU Yang, CHEN Yuhuan, FANG Jing, YANG Fang
    2024, 43(4):  2001-2016.  doi:10.16085/j.issn.1000-6613.2023-0626
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    Pseudo-protein is a new synthetic biodegradable material. It takes amino acids as the basic structural unit. Unlike protein, pseudo-protein has other linking groups in addition to peptide bonds, which gives it not only the excellent properties of proteins, but also the good mechanical properties, thermal properties, adjustable physicochemical properties, excellent cytocompatibility, 3D microporous structure, etc. Therefore, pseudo-proteins can be effectively applied in carriers, wound healing, tissue engineering, etc. Firstly, this paper reviews the types of pseudo-proteins studied so far, including non-functional and functional pseudo-proteins, followed by a detailed description of the methods for the synthesis of pseudo-proteins by condensation, including solution polycondensation, interfacial polymerization, melt polycondensation and ring-opening polymerization, and then summarizes the applications of pseudo-protein biomaterials in drug carrier, gene carrier, tissue engineering and wound dressing. Finally, the future development of synthetic routes and applications of pseudo-protein biomaterials is prospected.

    Fine chemicals
    Research advances of preparation of Pickering emulsions and their stability
    QI Yabing, WU Zibo, YANG Qingcui
    2024, 43(4):  2017-2030.  doi:10.16085/j.issn.1000-6613.2023-0528
    Abstract ( 28 )   HTML ( 0)   PDF (2615KB) ( 16 )  
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    Pickering emulsion refers to an emulsion which is stabilized by ultrafine solid particles or solid colloidal particles instead of traditional surfactants. It is widely applied in many fields involving petroleum, water treatment, cosmetics, food, pharmacy and materials industries due to its advantages such as excellent stability, convenient regulation, environment protection and low cost. In view of preparation and stability of Pickering emulsions, the preparation methods of Pickering emulsions were reviewed systematically. Then, the pattern and research progress of solid emulsifier particles were sketched. Besides, the stability mechanism of Pickering emulsions were revealed. Furthermore, the influencing factors on stability of Pickering emulsions were analyzed. And then, the existing problems of Pickering emulsions were discussed. Finally, the development trends of Pickering emulsions were outlooked. In future, the progress of Pickering emulsion were mainly shown in the following three aspects. ① The cheap, environment-friendly and reused Pickering emulsions with unmodified or modified natural solid nanoparticles were realized. ② The intelligent responsive Pickering emulsions (temperature, pH, magnetic and other response types) were applied in preparation of materials, slowly release or recovery of substance, catalytic reaction and so on. ③ The structure of solid emulsifier particles and emulsions were accurately controlled, and the systemized theory of emulsions preparation was established through deeply investigating the stability mechanism of Pickering emulsions.

    Resources and environmental engineering
    Progress on direct air capture of carbon dioxide
    LIAO Changjian, ZHANG Kewei, WANG Jing, ZENG Xiangyu, JIN Ping, LIU Zhiyu
    2024, 43(4):  2031-2048.  doi:10.16085/j.issn.1000-6613.2023-0606
    Abstract ( 31 )   HTML ( 4)   PDF (3385KB) ( 34 )  
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    Direct air capture (DAC) of carbon dioxide technology is a kind of negative carbon technology. As one of the important technologies to help achieving the carbon peaking and carbon neutrality goals, DAC technology has great development prospects. The development history of DAC and the operation and development of existing DAC projects were briefly described, and some liquid DAC technologies and solid DAC technologies were introduced. The liquid DAC technologies included aqueous hydroxide sorbents, aqueous basic solutions, aqueous amino acids/BIGs and alkalinity concentration swing technologies. The solid DAC technologies included solid alkali carbonates, solid-supported amine materials, MOFs materials,moisture swing technology and so on. The technological process and related equipment of various DAC technology were summarized. The principle of various DAC technologies, carbon dioxide capture methods and adsorbent/absorbent regeneration methods were described in detail. The advantages and disadvantages of each DAC technology in terms of adsorbent/absorbent performance, regeneration temperature, regeneration energy consumption and cycle stability were analyzed. It was pointed out that it was necessary to further develop DAC adsorbents/absorbents with low cost, high adsorption/absorption performance and good cycle stability, optimize and develop adsorbent/absorbent regeneration process, and develop process strengthening technology suitable for DAC technology, so as to lay a foundation for the subsequent large-scale and commercial application of DAC.

    Practice and development of leak detection and repair technology in petroleum refining and petrochemical industry in the United States
    LI Lingbo
    2024, 43(4):  2049-2062.  doi:10.16085/j.issn.1000-6613.2023-0641
    Abstract ( 19 )   HTML ( 0)   PDF (2250KB) ( 15 )  
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    The U.S. Environmental Protection Agency (EPA) was the first in the world to introduce leak detection and repair technology (LDAR) to control fugitive volatile organic compounds (VOCs) emissions from equipment leaks in petroleum refining and petrochemical industry. They have experienced the primary (1983—1999) and enhanced (around 2000—2020) stages, and is currently in the early stage of technological innovation. Their development history and experience are significant reference for policies, regulations, standards and techniques related to LDAR in China. This paper outlines the foundation and development of LDAR, technological progress and quality improvement in the United States, as well as the equivalent emission reduction policies and alternative means of emission control for LDAR. Additionally, the progress of technical innovations and the application such as optical gas imaging (OGI) detection, low-emission techniques, sensor-based automated and continuous detection and other high temporal and spatial resolution monitoring technologies is discussed and compared to LDAR. The future development of LDAR technology upgrades and innovations is explored. In general, the United States lead the world in the development and application of innovative LDAR technologies such as sensor-based leak detection, OGI detection and low-emission sealing techniques. Intelligent leak detection sensor network will probably be the dominant direction of LDAR technology innovation or next-generation LDAR research and development. Low-emission sealing technology will probably be an important auxiliary method to LDAR, while OGI will be an important alternative and supplementary LDAR detection technology.

    Recent advances in safely efficient deep emission reduction, recovery and thermal oxidation of VOCs from petrochemical storage tanks in China
    LIU Shida, WANG Haiyan, HOU Shuandi, LIU Zhongsheng, LIAO Changjian, WANG Kuanling
    2024, 43(4):  2063-2076.  doi:10.16085/j.issn.1000-6613.2023-0623
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    This review summarized the VOCs generation and emission mechanisms, emission characteristics, as well as the progress in VOCs reduction, recovery and thermal oxidation technologies for the petrochemical storage tanks. It proposes opinions and suggestions, aiming to contribute to the deep reduction of VOCs emissions from petrochemical storage tanks in China. Besides the gas generation from the large and small breathing of storage tanks, there are also gas generation phenomena such as high temperature heavy oil thermal cracking. When calculating the combustible gas concentration in tank emissions, components such as hydrogen sulfide, methane, hydrogen and ammonia should not be overlooked. The current VOCs control for storage tanks in China and the United States mainly focuses on source reduction through the use of floating roof tanks, with process control during tank operation and end-of-pipe treatment as supplementary measures. However, it is difficult to meet increasingly strict environmental requirements. It is suggested that China should revise the current standards in a timely manner. According to calculations, the VOCs emissions from organic liquid storage tanks in China in 2019 were estimated to be approximately 392000t to 904000t, mainly from petrochemical enterprises. It is recommended to prioritize control emissions from intermediate product tanks such as crude diesel, crude gasoline, crude aviation kerosene, wax oil, fuel oil, and residual oil, together with tanks containing benzene, toluene, xylene, methanol, and other substances. It is proposed that China should carry out deep reduction of VOCs emissions from petrochemical storage tanks, including source reduction, process control and end-of-pipe treatment. The internal floating roof tanks with built-in gas bag could become another important source reduction technology following floating roofs. It is also emphasized that compared to absorption and condensation, low-temperature diesel absorption have advantages in treating exhaust gases from tanks with high sulfur content, such as crude gasoline, crude diesel, and high-temperature heavy oil. Furthermore, it is noted that overall VOCs control for external emissions from petrochemical storage tanks in China is transitioning from recovery to combined recovery and thermal oxidation (catalytic oxidation, regenerative thermal oxidation, incinerators, process heating furnaces, boilers). The control target for non-methane total hydrocarbons at the outlet of thermal oxidation units is set to be less than 20mg/m3.

    Research progress of novel hydrometallurgy in recycling cathode materials from spent lithium-ion batteries
    MA Wenjun, ZHANG Xu, LIU Mengshun, LIANG Zhiyuan
    2024, 43(4):  2077-2090.  doi:10.16085/j.issn.1000-6613.2023-0547
    Abstract ( 27 )   HTML ( 3)   PDF (3055KB) ( 14 )  
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    The green and efficient recycling of cobalt, nickel, lithium and other rare metals in spent lithium batteries has gradually become the focus of research at home and abroad. Traditional acid leaching owns the advantages of low energy cost, high purity of metal recovery and high efficiency. However, traditional acid leaching uses caustic acids and expensive extracts, takes a long time and produces secondary waste such as waste acids, sludge and highly saline solutions. Therefore, this paper focused on the application of green leaching agent and reducing agent in traditional acid-leaching and two novel green solvents of deep eutectic solvent (DES) and supercritical fluid (SCF) in the green and efficient recovery of cathode materials of lithium batteries. The important effects of selective leaching technology on simplifying recovery procedures and assisted means like microwave or ultrasonic on improving leaching conditions were reviewed. The application of supercritical water (SCW) and supercritical carbon dioxide (SC-CO2) to degrade organic pollutants, recover rare metals, and improve the synthesis of cathode materials was emphasized, which provided important reference value for efficient, green and low-cost recovery of valuable metals from spent lithium batteries.

    Review of experimental and numerical simulation research on the development of natural gas hydrate reservoir with underlying gas
    SUN Xian, LIU Jun, WANG Xiaohui, SUN Changyu, CHEN Guangjin
    2024, 43(4):  2091-2103.  doi:10.16085/j.issn.1000-6613.2023-0676
    Abstract ( 11 )   HTML ( 0)   PDF (6459KB) ( 5 )  
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    Class 1 hydrate deposits consist of an upper hydrate layer and a lower two-phase flow layer containing free gas, which are the preferred target for natural gas hydrate exploitation. This paper introduces the characteristics and trial production of the class 1 hydrate reservoirs, and reviews the related experimental and numerical simulation researches. In terms of the experimental research, the remodeling of the class 1 accumulation and the subsequent hydrate decomposition research are summarized. It is found that most of the experimental studies on class 1 hydrate reservoirs have certain limitations in reservoir shaping. The underlying gas of hydrate reservoirs synthesized in many experimental studies is pure gas without porous media, which cannot simulate the mass transfer process of class 1 hydrate reservoirs. Moreover, the gas production rate in different gas production stages is significantly different, and the gas production rate in the initial stage is faster. It is assumed that the model establishment idea that hydrate decomposition occurs on a sharp interface is not applicable to the numerical simulation study of the class 1 hydrate reservoir decomposition because the class 1 hydrate reservoir has multiple decomposition fronts at the same time during the decomposition stage. The future research direction of the class 1 deposits is also proposed. It is suggested to expand the research scale and simulate the stress of hydrate reservoirs in natural marine environment, so as to be closer to the natural hydrate accumulation environment and improve the reference of experimental results.

    Research status and suggestions of yellow hosphorus production technology by thermal processing under peak carbon dioxide emission and carbon neutrality
    YAO Yuan, JING Hongquan, YIN Yuting, QI Shuailiang, WANG Yanyu. HOU Cuihong
    2024, 43(4):  2104-2116.  doi:10.16085/j.issn.1000-6613.2023-0560
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    Yellow phosphorus is the important basic raw material of phosphorus chemical industry, which supports our phosphate refinement and the development of organic phosphorus chemical industry. Thermal yellow phosphorus production has the characteristics of high energy consumption, high pollution and high carbon emission. It is the only way for Chinese yellow phosphorus enterprises to innovate the sustainable development mode of industry, to break through the multiple constraints of resources, energy and environment, and to develop green yellow phosphorus production technology. Combined with the time background of "carbon peak and carbon neutrality", this paper described the development of yellow phosphorus production technology and the status quo of by-product resource utilization. There were some problems in yellow phosphorus production, such as phosphate ore resource depletion, widespread utilization of low-value by-products, high difficulty in energy transformation, low overall energy efficiency level of enterprises and insufficient key technologies of industrial chain link. In order to realize energy saving and carbon reduction and green development of yellow phosphorus industry, this paper put forward five suggestions: to accelerate the promotion of pelletizing technology of low and medium grade phosphorus ore in tail gas sintering of yellow phosphorus, to increase the development of value-added utilization technology of resources, to explore new technology of yellow phosphorus reduction, to strengthen cooperation between enterprises, and to build a multi-industry coupled circular economy of phosphorus resource industry.

    Comprehensive evaluation on the typical utilization and disposal processes for resin powder from waste printed circuit boards by analytic network process
    ZONG Yuhang, CHI Yaxin, ZHANG Xihua, WANG Zhaolong, ZHENG Yang, JIANG Yongfang
    2024, 43(4):  2117-2125.  doi:10.16085/j.issn.1000-6613.2023-0585
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    Faced with the ever-increasing generation of waste printed circuit boards (WPCBs), waste resin powder obtained through mechanical and physical processes can cause a slew of issues, including resource waste and secondary contamination if not properly utilized and disposed. Thus, it is urgent to comprehensively evaluate the typical existing technologies for waste resin powder from WPCBs. This work constructed a network hierarchy relationship from five aspects, including resource, environment, economy, technology and society, to determine the linkage and feedback between the guidelines and indicators. Then, the ranking of the advantages and disadvantages towards three typical utilization and disposal technologies for waste resin powder from WPCBs, including landfill, incineration and mechanical processes, by a comprehensive evaluation method based on analytic network process (ANP) combined with expert scoring. It was found that the mechanical process could achieve the highest comprehensive level with excellent performance from the environmental, resourceful and economic criteria. Finally, the evaluation model developed in this study was applied to conduct a comprehensive evaluation in terms of criteria and indicators by taking a resource recycling enterprise in Suzhou as an example, and the validity of the established model was confirmed. The findings and conclusions were expected to provide theoretical basis and reference for the selection of technical routes for the industrial utilization and disposal of waste resin powder from WPCBs.

    Preparation of magnesium slag-based porous materials and their performance for Pb2+ adsorption in wastewater
    LU Guangjun, HAN Jingang, CHEN Ying, MA Zhibin
    2024, 43(4):  2126-2134.  doi:10.16085/j.issn.1000-6613.2023-0514
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    Magnesium slag-based porous materials (MSBPM) were prepared from magnesium slag by adding a composite exciter and foaming agent. Firstly, the effects of water glass modulus, alkali doping, blowing agent doping and roasting temperature on the mechanical and adsorption properties of MSBPM were investigated. The apparent morphology and porosity of MSBPM were observed and analyzed using scanning electron microscopy. Again, the adsorption performance of MSBPM on Pb2+ was investigated. The effects of parameters such as adsorbent dosing amount, initial concentration of solution, pH, adsorption time and temperature on the adsorption performance were studied. The results showed that the best adsorption performance of MSBPM on Pb2+ was achieved when the dosing of foaming agent was 8%, the dosing of alkali was 10% and the modulus was 1.3. The saturation adsorption capacity reached 303.95mg/g, which was 27% higher than that of the original magnesium slag. The compressive strength at this point was 2.84MPa. When the initial concentration of Pb2+ was 500mg/L, only 3.4g of adsorbent per liter of wastewater was required to achieve over 99% removal of Pb2+. The adsorption process was monolayer chemisorption, which was in accordance with the proposed secondary kinetic model.

    Simultaneous nitrogen and phosphorus removal and microbial community structure under autotrophic denitrification driven by complex sulfur substrate
    GE Sijie, YANG Daxin, LYU Jun, WANG Zhen, ZHANG Chuanyi, ZHANG Wenhua
    2024, 43(4):  2135-2143.  doi:10.16085/j.issn.1000-6613.2023-0629
    Abstract ( 16 )   HTML ( 0)   PDF (4505KB) ( 5 )  
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    Facing the drawback of autotrophic denitrification performance driven by a single sulfur base, three groups of complex sulfur substrate packed bed reactors (B1, B2, B3) were constructed by using elemental sulfur (S0) and natural iron sulfur ores (FeS, Fe1-x S, FeS2) as biological fillers. The deep nitrogen and phosphorus removal effect and microbial community structure characteristics of municipal tailwater were investigated during start-up and stable operation of the reactors. The results indicated that the high denitrification performance were obtained in the three reactors and the NO3--N removal efficiency increased with the extension of the reactor hydraulic retention time (HRT). When the reactor HRT was 12h (B1), 12h (B2) and 9h (B3), 20mg/L NO3--N was completely removed. The PO43--P was removed through chemical precipitation with iron ions generated in the denitrification process, and P removal rate was positively correlated with the effect of nitrogen removal. The SO42-/NO3- of the complex sulfur substrate reactor was lower than that of the single sulfur based autotrophic denitrification system. Also, sulfate production accordingly decreased and the pH was maintained above 6.3 without adding pH buffers. Microbial community structure analysis showed that Thiobacillus and Ferritrophicum were the dominant genera of sulfur autotrophic denitrifying bacteria in the three reactors. The relative abundances of Thiobacillus and Ferritrophicum in B1, B2 and B3 reactors were 16.07% and 31.24%, 30.07% and 50.19%, and 30.20% and 11.62%, respectively. The complex sulfur substrate enhanced the richness and species diversity of microbial communities, which showed better nitrogen and phosphorus removal performance.

    Effect of bituminous coal mixing on the electro-dewatering performance of sludge
    SHA Li, SU Yingjia, LING Zichen, YU Xiaoyan, LI Shupeng, GUO Lili, XIONG Jing, FANG Lianhu, ZHANG Ran, ZHANG Shuting
    2024, 43(4):  2144-2152.  doi:10.16085/j.issn.1000-6613.2023-2258
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    To promote the process of resource utilization of sludge incineration, this article used bituminous coal to mix activated sludge, and then the electro-dewatering performance of the mixed sludge was studied. The variations of physical and chemical properties, organic properties, and low calorific value of mixed sludge during the electro-dewatering process were examined. The results showed that the dewatering content of sludge first increased and then decreased with the increase in bituminous coal dosage. When the optimal coal dosage was 50%DS, the moisture content of the mixed sludge decreased from 81%±0.8% to 50.1%±0.6%, and the dewatering time was shortened by 30.8% compared to no-mixed sludge. Mixing bituminous coal could improve the conductivity and Ohmic heating effect of sludge, thereby improving the dewatering efficiency. The moisture content of sludge was highly correlated with the content of hydrophilic amino acids such as threonine, serine, histidine, glutamic acid, and hydrophobic amino acids such as valine (|r|>0.883, p<0.05). Electro-dewatering after mixing bituminous coal could reduce the content of hydrophilic amino acids and oxygen-containing functional groups in the sludge cake, improving the hydrophobicity of the sludge. After the electro-dewatering of mixed sludge, the low calorific value of sludge cake was increased by more than 60% compared to the no-mixed electro-dewatering treatment. This result was helpful for the subsequent resource utilization of mixed combustion of sludge and coal.

    Transfer behaviors of dissolved organic matter along stripping purified water reusing crude oil electric desalting process
    ZHANG Rui, KOU Yue, SUN He, WANG Chenyu, LI Zhuoyu, WANG Qinghong, CHEN Chunmao
    2024, 43(4):  2153-2160.  doi:10.16085/j.issn.1000-6613.2023-0559
    Abstract ( 17 )   HTML ( 0)   PDF (2590KB) ( 4 )  
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    The reusing of stripping purified water (SPW) in crude oil electric desalting process (EDP) is an efficient water-saving measure for petroleum refineries. In this study, a comprehensive analysis based on gas chromatography-mass spectrometry (GC-MS) and orbitrap mass spectrometry (Orbitrap MS) was established, and the transfer behaviors of dissolved organic matter (DOM) along SPW reusing crude oil EDP were investigated at the micro-level. During EDP, 13 types of aromatic amines, 34 types of nitrogen-containing heterocycles, 13 types of medium-/long-chain alkylphenols and 1 type of ether in SPW were transferred into oil phase. The quality of crude oil was not deteriorated while the yield slightly increased, and the total organic load in electric desalting wastewater (EDW) reduced by 50%. Simultaneously, 8 types of naphthenic acids, 7 types of oxygen-containing heterocycles, 3 types of short-chain alkylphenols, 504 types of O2, O4, O3S1, N1O3 species with low unsaturation and 186 types of O4S1, N1O2 species with high unsaturation originally in crude oil were transferred into water phase, increasing the complexity of DOM constituents and acute bio-toxicity of EDW. The results enhanced insights to highly polluted point-source wastewaters and improved the management of petroleum refineries.

    Technique of wet carbonation of modified magnesium slag
    SUN Weiji, LIU Lang, FANG Zhiyu, ZHU Mengbo, XIE Geng, HE Wei, GAO Yuheng
    2024, 43(4):  2161-2173.  doi:10.16085/j.issn.1000-6613.2023-0660
    Abstract ( 19 )   HTML ( 0)   PDF (7014KB) ( 19 )  
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    Carbonation reaction of alkali-based industrial solid waste is one of the carbon sequestration strategies for mineralization to absorb CO2 and reduce greenhouse gas emissions. In this study, the wet carbonation process was introduced for the first time, and through experimental tests using XRD, FTIR and TG-DTG, it was focused on exploring the effects of temperature change, stirring speed, carbonation time and liquid-solid ratio on the carbonation reaction of modified magnesium slag, and then discussed the carbonation products and carbon sequestration efficiency of modified magnesium slag under the four factors. The results showed that the mineral composition of modified magnesium slag was mainly dominated by β-C2S, which was an industrial solid waste with good CO2 storage capacity, and the carbonation products were mainly dominated by calcite-type calcium carbonate crystals and silica gel. After the carbonation reaction, the particle size of the modified magnesium slag carbonation product increased significantly, the specific surface area decreased, the particle size distribution became more uniform and the particle size distribution range became narrower. When the carbonation reaction temperature was 60℃, the aeration time was 30min, the liquid-solid ratio was 10mL/g and the stirring speed was 600r/min, the carbon sequestration efficiency of modified magnesium slag reached the maximum (28.4%), i.e. 1kg of modified magnesium slag could be mineralized to absorb 0.284kg of CO2. Therefore, the wet carbonation process had a great application for the recycling of modified magnesium slag and the carbon dioxide sequestration potential.

    Optimization of preferential lithium extraction from waste ternary lithium ion batteries by carbothermal reduction
    ZHOU Mingxian, YE Xiaozhou
    2024, 43(4):  2174-2182.  doi:10.16085/j.issn.1000-6613.2023-0539
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    The process of carbon thermal reduction-CO2 water immersion was used to preferentially extract lithium from the cathode materials of spent ternary lithium ion batteries. The variables were changed individually such as roasting temperature, roasting duration, effective carbon addition, water leaching duration, solid liquid ratio, CO2 flow rate and countercurrent water washing order to investigate the effects on the leaching rate of metal elements. When roasting temperature was 700℃, roasting time was 120min, effective carbon addition(75.56% carbon powder) was 14% (weight), liquid solid ratio was 10mL/g, water leaching time was 180min, CO2 flow rate was 100mL/min and three stage countercurrent water washing, the leaching rate of lithium could reach 96.31%, and the leaching rates of cobalt, nickel and manganese metals were all lower than 0.1%. This process was applicable to different types of NCM batteries. In addition, the phase changes before and after carbothermal reduction were investigated by XRD, TEM and SEM-EDS.

    Two-electron water oxidation reaction assisted electrochemical oxidation with boron doped diamond to inhibit ClO3- and ClO4- formation
    DING Jia, WU Wenqi, LI Pengcheng
    2024, 43(4):  2183-2190.  doi:10.16085/j.issn.1000-6613.2023-0699
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    Boron-doped diamond (BDD) electrodes have been widespread applied in the treatment of refractory organic pollutants for their advantages of efficient production of hydroxyl radical (·OH) and high stability. However, chlorate (ClO3-) and perchlorate (ClO4-), which are toxic by-products produced in the process of electrolysis of chlorine-containing medium, is one of the key obstacles to the application of BDD electrodes. In this work, we developed a method to use two-electron water oxidation reaction (2e-WOR) assisted electrochemical oxidation with BDD to inhibit ClO3- and ClO4- formation in the water treatment, meanwhile, studied the degradation effects of atrazine (ATZ), which was one of the most popular herbicides as a model organic pollutant. The results indicated that the presence of NaHCO3 effectively promoted the production of H2O2 by 2e-WOR, which decreased the concentration of active chlorate (AC), ClO3- and ClO4-. The concentration of AC was reduced by 60.3% in the presence of 10mmol/L NaHCO3, the suppression rates of ClO3- and ClO4- were 10.2% and 39.2%. Adding 50mmol/L and 100mmol/L NaHCO3 resulted in a decrease of 60.0% and 72.50% in the ClO3- accumulation rate and 66.2% and 72.60% in the ClO4- accumulation rate. The mechanism of suppression of ClO3- and ClO4- by 2e-WOR was as followed. Firstly, H2O2 which was produced by 2e-WOR decreased the concentration of the key intermediate—AC by reacting with it, which reduced the concentration of ClO3- and ClO4-. Secondly, HCO3- competed with ClO3- for ·OH, then reduced the conversion rate of ClO3- to ClO4- . The appropriate concentration of NaHCO3 was conducive to the degradation of ATZ. The addition of NaHCO3 was improved by 27.2% and 53.8% in the presence of 10mmol/L and 50mmol/L NaHCO3, Scavenging experiment indicated that the addition of NaHCO3 was beneficial to the improvement of degradation of ATZ in the homogeneous solution.

    Impacts of CeO2 oxygen carriers on the conversion of mercury in chemical looping combustion of coal
    WANG Xudong, LIU Dunyu, XU Kailong, LIU Qiuqi, FAN Yunpei, JIN Jing
    2024, 43(4):  2191-2200.  doi:10.16085/j.issn.1000-6613.2023-0521
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    Mercury pollution has attracted increasing attention due to serious harm to the human beings and ecosystem. This study aims to analyze the effects of CeO2 oxygen carriers on the conversion of mercury during coal chemical looping combustion. The combustion characteristics of "CeO2+coal", "SiO2+coal" and "coal" in the fluidized bed reactor were investigated experimentally. In gasification atmosphere, the reaction between oxygen carrier and coal was mainly converted to CO2 and a small amount of compositions including CO, CH4, and H2 . "CeO2+coal" system consumed the largest amount of O2 and produced the largest amount of CO2, indicating that the CeO2 oxygen carriers contributed to the fully combustion of the coal. Mercury was mainly released as Hg0 in the gasification atmosphere, and the Hg0 release from "CeO2 + coal" accounted for 49.75% of the total mercury, which was significantly lower than that of the system without oxygen carriers. In air atmosphere, mercury was released in the form of Hg2+ with a small amount. The Hg0 and Hg2+ release from "CeO2 + coal" system were both lower than those of the "coal" system. By changing the different locations between CeO2 oxygen carriers and coal in experiments, it was shown that under gasification atmosphere, CeO2 oxygen carriers had weak adsorption capacity for Hg0, and their catalytic and oxygen release properties were the key factors in removing Hg0, and the catalytic activity played a major role. Under gasification atmosphere, CO2 could replenish the lattice oxygen consumed in CeO2, thus improving its catalytic and regenerative performances. XPS analysis of the CeO2 oxygen carriers after reduction and oxidation showed the peak position for Ce3+ in Ce 3d disappeared and all of them were converted to Ce4+, which indicated that the CeO2 oxygen carrier had good cyclic performance.

    Rapid start-up performance of mainstream Anammox in a single-stage fixed-bed biofilm reactor
    HAI Yan, ZHOU Xin, LI Yan
    2024, 43(4):  2201-2209.  doi:10.16085/j.issn.1000-6613.2023-0541
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    Mainstream anaerobic ammonium oxidation (Anammox) is a hotspot and difficulty issue for nitrogen removal from municipal wastewater. In this study, a single-stage fixed-bed biofilm reactor (SFBR) was used to treat simulated municipal wastewater. By switching from intermittent operation and controlling low-oxygen (DO: 0.4—0.7mg/L), mainstream Anammox was successfully started up after 65 days, and the system achieved removal efficiencies of ammonia nitrogen and total nitrogen up to 98.8% and 92.6%, respectively. At this moment, the biofilm structure was dense and appeared red. Microbial activity test showed that the activity of Anammox bacteria (SAA) was the highest among all the functional bacteria. High-throughput sequencing confirmed that the co-existence of Anammox genus (Candidatus Brocadia), partial denitrification genus (Thauera) and nitrifying genus (Nitrospira), but ammonia oxidizing bacteria was not detected. Further analysis of the amoA functional gene amplicon indicated that Nitrospira was actually complete ammonia oxidizing (Comammox) bacteria. Therefore, the system achieved nitrogen removal from municipal wastewater through the coupled pathway of complete nitrification/partial denitrification/Anammox within an oxygen-stratified biofilm. These study findings provided a new process idea for the rapid realization of mainstream Anammox.

    Establishment of separation method for polysulfide ions in wet desulfurization
    GAO Kang, ZHANG Xian, CHEN Shuaijun, WU Ximing, SHEN Jun, WANG Yugao, NIU Yanxia
    2024, 43(4):  2210-2218.  doi:10.16085/j.issn.1000-6613.2023-0689
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    Polysulfide ion Sx2- is an intermediate product of the conversion of H2S to elemental sulfur in wet catalytic oxidation desulfurization technology. In the desulfurization environment, there is a parallel competition between the sulfur evolution reaction and parasite reaction, and the existing form and concentration of Sx2- are the prerequisite for evaluating the degree of the two competitive reactions. In this paper, UV-vis, LC-MS, and HPLC methods were used to determine the existence and concentration of Sx2-. The results showed that the total concentration of Sx2- could be determined by the UV-vis method. The methylation method could capture each form of Sx2-, LC-MS and HPLC methods could separate each form of methylated polysulfide, and the larger the number of sulfur atoms (2—10) of Sx2-, the longer the retention time. Combined with the standard curve established by UV-vis and the relative intensity of each form of Sx2- on HPLC, the absolute concentration of each form of Sx2- in solution was calculated. S42-, S52-, S62- and S102- were the main types of sodium polysulfide solution, in which the concentration and pH had little effect on Sx2-, and the high temperature was not conducive to the formation of Sx2-, thus not conducive to the formation of elemental sulfur. This work laid a foundation for further research on the origin of parasites and the acceleration of sulfur evolution.

    Effect of pH on MEC desulfurization performance and microbial mechanism of action
    GUO Meng, GUO Meixin, WEI Sijia, ZHAO Yujiao, JIA Xuan
    2024, 43(4):  2219-2225.  doi:10.16085/j.issn.1000-6613.2023-0686
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    The use of microbial electrolysis cells (MEC) technology, in conjunction with the cooperative action of electroactive microorganisms on the anode, achieves the removal of sulfides. This is a new process for biogas desulfurization and a research hotspot. For long-term operation of the desulfurization MEC process, non-specific cation competition causes proton transfer from the anode to the cathode to be impeded, resulting in low desulfurization efficiency and unstable operation. In this study, different initial pH values were used to regulate the proton balance in the desulfurization MEC. Through analysis of desulfurization performance, electrochemical performance, and microbial kinetics, the influence of pH regulation on the desulfurization performance of the MEC and the microbial mechanism were elucidated. The findings demonstrated that highly effective and stable anode biofilms capable of removing sulfides could be established at initial pH between 7 and 9, with comparable maximum current densities, sulfide removal efficiencies exceeding 95%, and COD removal rates over 80%. In comparison to initial pH of 8 and 9, pH fluctuation during the desulfurization process was minimized at an initial pH of 7, contributing to greater MEC stability and S2- removal rates reaching up to 100%. The oxidation-reduction peak of the anode biofilm was pronounced, with accelerated proton and electron transfer rates. Thiomonas and Desulfovibrio microorganisms were dominant, exhibiting higher abundance and primarily involved in the oxidation removal of sulfides. These results underscored the importance of regulating the initial pH of the MEC anode chamber to improve MEC desulfurization efficiency and operational stability while providing valuable technical support for microbial electrochemical biogas desulfurization applications.

    Red brick doping modified Baiyun Obo iron ore concentrate oxygen carrier performance
    ZHANG Pengfei, CHEN Weipeng, XIAO Zhuonan, LYU Qinggang, ZHANG Shunfeng, ZHANG Zifeng
    2024, 43(4):  2226-2234.  doi:10.16085/j.issn.1000-6613.2023-0549
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    The modified Baiyun Obo iron ore concentrate oxygen carrier was prepared by mechanical mixing method with the addition of red brick powder from construction solid waste, and the effect of red brick powder addition on CO chemical chain combustion performance was analyzed by thermogravimetric analyzer and tube furnace experiments, and the mechanism was analyzed by means of characterization such as SEM, XRD, BET, and kinetic analyses. Through the DTG curve, it could be seen that the reaction temperature of Baiyun Ebo iron ore concentrate carrier with CO was basically higher than 800℃, and the red brick powder modified carrier could enhance the chemical chain combustion reaction rate and accelerate the reaction process, especially for the 2.5% red brick modified sample, the reaction effect was optimal at 950℃, and the CO2 yield reaches 87%. The kinetic analysis of the programmed heating experimental data revealed that the red brick powder could shorten the reaction time with CO and accelerate the reaction process, and based on the cyclic reaction experiments, the modified oxygen carrier exhibited a more stable carbon conversion rate. The improved reactivity and enhanced cyclic stability were mainly due to the higher specific surface area and pore structure of the oxygen carriers by the red brick powder.

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