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SCI和EI收录∣中国化工学会会刊
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Table of Content
28 July 2023, Volume 59 Issue 7
    Role of iron-based catalysts in reducing NOx emissions from coal combustion
    Yuehua Liu, Lili Chen, Shoujun Liu, Song Yang, Ju Shangguan
    2023, 59(7):  1-8.  doi:10.1016/j.cjche.2022.11.017
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    Nitrogen oxide (NOx) pollutants emitted from coal combustion are attracting growing public concern. While the traditional technologies of reducing NOx were mainly focused on terminal treatment, and the research on source treatment is limited. This paper proposes a new coal combustion strategy that significantly reduces NOx emissions during coal combustion. This strategy has two important advantages in reducing NOx emissions. First, by introducing iron-based catalyst at the source, which will catalyze the conversion of coke nitrogen to volatile nitrogen during the pyrolysis process, thereby greatly reducing the coke nitrogen content. The second is de-NOx process by a redox reaction between NOx and reducing agents (coke, HCN, NH3, etc.) that occurred during coke combustion. Compared to direct combustion of coal, coke prepared by adding iron-based catalyst has 46.1% reduction in NOx emissions. To determine the effect of iron-based additives on de-NOx performance, demineralized coal (de-coal) was prepared to eliminate the effect of iron-based minerals in coal ash. The effects of iron compounds, additive dosages, and combustion temperatures on de-NOx efficiency are systematically studied. The results revealed that the NOx emission of the coke generated by pyrolysis of de-coal loaded with 3% (mass) Fe2O3 decreases to 27.3% at combustion temperature of 900 ℃. Two main reasons for lower NOx emissions were deduced: (1) During the catalytic coal pyrolysis stage, the nitrogen content in the coke decreases with the release of volatile nitrogen. (2) Part of the NOx emitted during the coke combustion was converted into N2 for the catalytic effect of the Fe-based catalysts. It is of great practical value and scientific significance to the comprehensive treatment and the clean utilization process of coal.
    One-step ethylene separation from ternary C2 hydrocarbon mixture with a robust zirconium metal-organic framework
    Yuan Liu, Hanting Xiong, Jingwen Chen, Shixia Chen, Zhenyu Zhou, Zheling Zeng, Shuguang Deng, Jun Wang
    2023, 59(7):  9-15.  doi:10.1016/j.cjche.2023.01.001
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    One-step separation of high-purity ethylene (C2H4) from C2 hydrocarbon mixture is critical but challenging because of the very similar molecular sizes and physical properties of C2H4, ethane (C2H6), and acetylene (C2H2). Herein, we report a robust zirconium metal-organic framework (MOF) Zr-TCA (H3TCA = 4,4',4″-tricarboxytriphenylamine) with suitable pore size (0.6 nm×0.7 nm) and pore environment for direct C2H4 purification from C2H4/C2H2/C2H6 gas-mixture. Computational studies indicate that the abundant oxygen atoms and non-polar phenyl rings created favorable pore environments for the preferential binding of C2H2 and C2H6 over C2H4. As a result, Zr-TCA exhibits not only high C2H6 (2.28 mmol·g-1) and C2H2 (2.78 mmol·g-1) adsorption capacity but also excellent C2H6/C2H4 (2.72) and C2H2/C2H4 (5.64) selectivity, surpassing most of one-step C2H4 purification MOF materials. Dynamic breakthrough experiments confirm that Zr-TCA can produce high-purity C2H4 (>99.9%) from a ternary gas mixture (1/9/90 C2H2/C2H6/C2H4) in a single step with a high C2H4 productivity of 5.61 L·kg-1.
    Synthesis, characterization, and performance comparison of boron using adsorbents based on N-methyl-D-glucosamine
    Hui Jiang, Zijian Zhao, Ning Yu, Yi Qin, Zhengwei Luo, Wenhua Geng, Jianliang Zhu
    2023, 59(7):  16-31.  doi:10.1016/j.cjche.2023.01.012
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    Using N-methyl-D-glucosamine (NMDG) as the functional monomer, glycidyl methacrylate (GMA) as the connecting monomer, functionalized Fe3O4 nano-particles (NPs) as the support, three adsorbents were prepared including direct polymer GMA-NMDG, magnetic GMA-NMDG polymer (MGN), and boron magnetic ion-imprinted polymer (BMIIP). Based upon the optimization of synthesis conditions, the prepared adsorbents and intermediate products were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, energy dispersive spectroscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer-Emmett-Teller to investigate the synthesis process, the morphological structure and the functional properties of the materials. The optimum performances of GMA-NMDG, MGN and BMIIP were obtained in the initial neutral solution (pH of 6.5). Moreover, GMA-NMDG and MGN reached the maximum adsorption capacity at 120 min, whereas BMIIP reached adsorption saturation at 60 min. The pseudo-second-order kinetic model was more suitable for the adsorption of boron using the adsorbents. The maximum adsorption capacity of GMA-NMDG was found to be 43.4 mg·g-1, while those of MGN and BMIIP were 32.5 and 28.3 mg·g-1, respectively. The Langmuir isotherm model was more appropriate to describe the adsorption process. The adsorbents maintained satisfactory adsorption performance within a certain temperature range. Competing ions had little effect on the adsorption of boron, and would be adsorbed simultaneously, due to which, the effect of co-adsorption can be considered. The adsorption capacity of GMA-NMDG was high, while the adsorption selectivity of BMIIP was much better. Furthermore, BMIIP showed good adsorption after five cycles of adsorption and desorption. The comparison of adsorbents showed that GMA-NMDG had the highest adsorption capacity and was suitable for co-adsorption. MGN had a high adsorption capacity, good comprehensive performance and magnetic properties. BMIIP had better adsorption rate, adsorption selectivity and recyclability. Through the optimization of synthesis conditions, the adsorption capacity of the traditional monomer NMDG polymer was increased, and the magnetism was given to facilitate rapid recovery. Combined with the ion imprinting technology, it showed higher boron adsorption selectivity in the presence of competitive ions.
    Ultrasonic cavitation-enabled microfluidic approach toward the continuous synthesis of cesium lead halide perovskite nanocrystals
    Mingzhi Li, Zhikai Liu, Wang Yao, Chao Xu, Yangping Yu, Mei Yang, Guangwen Chen
    2023, 59(7):  32-41.  doi:10.1016/j.cjche.2022.12.001
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    Ligand assisted reprecipitation (LARP) is a widely used method for cesium lead halide perovskite nanocrystals (NCs) synthesis. Nevertheless, the ultrafast kinetics of LARP, as well as the inefficient transport properties and discontinuity of batch reactors, challenge the particle size control and experimental repeatability. To address these issues, an ultrasonic cavitation-enabled microfluidic approach was developed to achieve the continuous synthesis of cesium lead halide perovskite via LARP. It was found that the mixing between the good solvent and antisolvent in the microchannel was greatly enhanced by intensive ultrasonic cavitation. The mixing time could be reduced to below 10 ms under the irradiation of 35 W ultrasound. By modulating the mixing degree, LARP was proved to be a mixing-sensitive process. The effects of ultrasonic power, ultrasonic treatment time, total flow rate, water additive, and reprecipitation temperature on the synthesis of CsPbBr3 NCs were systematically investigated. As compared to CsPbBr3 NCs synthesized in the batch reactor, the sample synthesized via the ultrasonic cavitation-enabled microfluidic approach possessed stronger photoluminescence intensity and better repeatability. Moreover, the ultrasonic cavitation-enabled microfluidic approach could also realize the continuous synthesis of cesium lead halide perovskite NCs with different halide compositions to cover a wide visible spectrum (426-661 nm). The ultrasonic cavitation-enabled microfluidic approach paved the way for the large-scale of high-quality cesium lead halide perovskite NCs.
    Performance comparison of lithium fractionation from magnesium via continuous selective nanofiltration/electrodialysis
    Yong Xu, Qingbai Chen, Yang Gao, Jianyou Wang, Huiqing Fan, Fei Zhao
    2023, 59(7):  42-50.  doi:10.1016/j.cjche.2022.11.013
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    Although selective nanofiltration (SNF) and selective electrodialysis (SED) have been widely adopted in the field of Mg2+/Li+ separation, their differences have not been illustrated systematically. In this study, for the first time, SNF and SED processes in continuous mode were studied for Li+ fractionation from the same brine with high Mg/Li ratios and their differences were discussed in detail. For a fair analysis of the two processes, typical factors were optimized. Specifically, the optimal operating pressure and feed flow rate for SNF were 2.4 MPa and 140 L·h-1, respectively, while the optimal cell-pair voltage and replenishment flow rate for SED were 1.0 V and 14 L·h-1, respectively. Although the Li+ fractionation capacity of the two processes were similar, the selectivity coefficient of SNF was 24.7% higher than that of SED and, thus, the Mg/Li ratio in purified stream of the former was 19.0% lower than that of the latter. Due to higher ion driving force, SED had clear advantages in recovery ratio and concentration effects. Meanwhile, the specific energy consumption of SED was 20.1% lower than that of SNF. This study provided a better understanding and guidance for the application and improvement of the two technologies.
    The internal circulations on internal mass transfer rate of a single drop in nonlinear uniaxial extensional flow
    Anjun Liu, Jie Chen, Meng Guo, Chengmin Chen, Meihong Yang, Chao Yang
    2023, 59(7):  51-60.  doi:10.1016/j.cjche.2022.12.003
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    The internal flow of a droplet in the nonlinear extensional flow field will exhibit more than two internal circulations with the variation of nonlinear intensity (E). In this paper, the effect of positions and sizes of internal circulations on internal mass transfer rate of a single spherical droplet in a nonlinear extensional flow field is studied and compared with that in a linear extensional flow field. The simulation results show that when E ≥ 0, there are two symmetrical internal circulations in the droplet, which is the same with that in a linear extensional flow. The limit value of mass transfer rate Sh is 15, which is equal to that in a linear extensional flow, no matter how large E is. When E ≤ -3/7, the number of internal flow circulation of a droplet increase to four and the transfer rate Sh increases. When E = -1, the maximum internal transfer rate Sh equals 30 which is twice of that in a linear extensional flow. The generation of new flow circulations in droplets and the circulation positions will enhance mass transfer when E ≤ -3/7, which provides a new idea for enhancing the internal mass transfer rate of droplets.
    Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation, one-stage urea complexation and five-stage solvent crystallization
    Yingxi Gao, Jiayi Shi, Jie Wang, Fan Zhang, Shichao Tian, Zhiyong Zhou, Zhongqi Ren
    2023, 59(7):  61-71.  doi:10.1016/j.cjche.2022.10.007
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    Nervonic acid is the world's first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value. The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult. A new combined process of molecular distillation, urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials. First, according to the difference in the mean free path of fatty acids, molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18-C20 fatty acids of stearic, oleic, linoleic, and linolenic acids. The content of C16-C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes, in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%. Then, according to the difference in carbon chain length and saturation of fatty acid, the contents of C22-C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification (SPOMFs) ratio as 0.6. In addition, all saturated fatty acids were basically separated. Finally, according to the difference in the solubility of fatty acids in solvents, the C18-C20 unsaturated fatty acids of oleic, linoleic, and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization. The content of C18-C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization. The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization. The combined process of molecular distillation, urea inclusion and low temperature crystallization innovatively adopted an efficient, simple and easy-to-industrial solvent crystallization method to separate erucic and nervonic acids, obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.
    Data cleaning method for the process of acid production with flue gas based on improved random forest
    Xiaoli Li, Minghua Liu, Kang Wang, Zhiqiang Liu, Guihai Li
    2023, 59(7):  72-84.  doi:10.1016/j.cjche.2022.12.013
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    Acid production with flue gas is a complex nonlinear process with multiple variables and strong coupling. The operation data is an important basis for state monitoring, optimal control, and fault diagnosis. However, the operating environment of acid production with flue gas is complex and there is much equipment. The data obtained by the detection equipment is seriously polluted and prone to abnormal phenomena such as data loss and outliers. Therefore, to solve the problem of abnormal data in the process of acid production with flue gas, a data cleaning method based on improved random forest is proposed. Firstly, an outlier data recognition model based on isolation forest is designed to identify and eliminate the outliers in the dataset. Secondly, an improved random forest regression model is established. Genetic algorithm is used to optimize the hyperparameters of the random forest regression model. Then the optimal parameter combination is found in the search space and the trend of data is predicted. Finally, the improved random forest data cleaning method is used to compensate for the missing data after eliminating abnormal data and the data cleaning is realized. Results show that the proposed method can accurately eliminate and compensate for the abnormal data in the process of acid production with flue gas. The method improves the accuracy of compensation for missing data. With the data after cleaning, a more accurate model can be established, which is significant to the subsequent temperature control. The conversion rate of SO2 can be further improved, thereby improving the yield of sulfuric acid and economic benefits.
    An efficient microreactor with continuous serially connected micromixers for the synthesis of superparamagnetic magnetite nanoparticles
    Wenting Fan, Fang Zhao, Ming Chen, Jian Li, Xuhong Guo
    2023, 59(7):  85-91.  doi:10.1016/j.cjche.2022.12.008
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    A new microreactor with continuous serially connected micromixers (CSCM) was tailored for the coprecipitation process to synthesize Fe3O4 nanoparticles. Numerical simulation reveals that the two types of CSCM microchannels (V-typed and U-typed) proposed in this work exhibited markedly better mixing performances than the Zigzag and capillary microchannels due to the promotion of Dean vortices. Complete mixing was achieved in the V-typed microchannel in 2.7 s at an inlet Reynolds number of 27. Fe3O4 nanoparticles synthesized in a planar glass microreactor with the V-typed microchannel, possessing an average size of 9.3 nm and exhibiting superparamagnetism, had obviously better dispersity and uniformity and higher crystallinity than those obtained in the capillary microreactor. The new CSCM microreactor developed in this work can act as a potent device to intensify the synthesis of similar inorganic nanoparticles via multistep chemical precipitation processes.
    Synthesis, performance and structure characterization of glyoxal-monomethylolurea-melamine (G-MMU-M) co-condensed resin
    Haixiang Liu, Jun Zhang, Chunlei Dong, Gang Zhu, Guanben Du, Shuduan Deng
    2023, 59(7):  92-104.  doi:10.1016/j.cjche.2022.09.022
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    In order to reduce the formaldehyde emission of formaldehyde-based wood adhesive from the source, it is aimed to develop a novel co-condensed resin of glyoxal-monomethylolurea-melamine (G-MMU-M). A series of G-MMU-M resins with various formulations of raw materials were successfully prepared. The basic properties and bonding performance of the G-MMU-M resins were determined. Furthermore, the structures of resins were characterized by FTIR, 13C NMR, XPS, and ESI-MS. The results show that the prepared G-MMU-M resin remains stable for 30 d, meanwhile, the dry and wet bonding strength of the plywoods bonded with the resins, solid content and viscosity are influenced greatly by the addition amount of melamine and MMU/G molar ratio. The G-MMU-M resins with MMU/G molar ratio of 0.9:1.0 and 8% melamine exhibit the highest dry and bonding strength of 1.98 MPa and 1.27 MPa, increased by 34% and 63%, respectively, in comparison with glyoxal-monomethylolurea (G-MMU) resin. In the G-MMU-M resins, there were four main oligomers including M—CH(—+CH-MMU)-O-MMU, M-CH(—CH2OH)-MMU-O-MMU, M—CH(—OH)—+CH-MMU-O-MMU, and M—CH(—+CH-MMU)-MMU-p-G.
    Effect of carbon dioxide on oxy-fuel combustion of hydrogen sulfide: An experimental and kinetic modeling
    Xun Tao, Fan Zhou, Xinlei Yu, Songling Guo, Yunfei Gao, Lu Ding, Guangsuo Yu, Zhenghua Dai, Fuchen Wang
    2023, 59(7):  105-117.  doi:10.1016/j.cjche.2022.11.014
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    CO2 is an important component in the acid gas and it is necessary to study the effect of CO2 presence on the oxy-fuel combustion of H2S with particular focus on the formation of carbonyl sulfide (COS). The oxy-fuel combustion of acid gas was conducted in a coaxial jet double channel burner. The distribution of flame temperature and products under stoichiometric condition along axial (R = 0.0) and radial at about 3.0 mm (R = 0.75) were analyzed, respectively. The Chemkin-Pro software was used to analyze the rate of production (ROP) for gas products and the reaction pathway of acid gas combustion. Both experimental and simulation results showed that acid gas combustion experienced the H2S chemical decomposition, H2S oxidation and accompanied by H2 oxidation. The CO2 presence reduced the peak flame temperature and triggered the formation of COS in the flame area. COS formation at R = 0.0 was mainly through the reaction of CO2 and CO with sulfur species, whereas at R = 0.75 it was through the reaction of CO with sulfur species. The ROP results indicated that H2 was mainly from H2O decomposition in the H2S oxidation stage, and COS was formed by the reaction of CO2 with H2S. ROP and other detailed analysis further revealed the role of H, OH and SH radicals in each stage of H2S conversion. This study revealed the COS formation mechanisms with CO2 presence in the oxy-fuel combustion of H2S and could offer important insights for pollutant control.
    Facile wet-chemical fabrication of bi-functional coordination polymer nanosheets for high-performance energy storage and anti-corrosion engineering
    Minjie Shi, Nianting Chen, Yue Zhao, Cheng Yang, Chao Yan
    2023, 59(7):  118-127.  doi:10.1016/j.cjche.2022.11.011
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    Organic materials are of great interest in various applications owing to their intrinsic designability, molecular controllability, ease of synthesis, and ecological sustainability. In this work, a facile and mild wet-chemical strategy was carried out to construct a conjugated Ni-BTA coordination polymer via the π-d hybridization with 1,2,4,5-benzenetetramine (BTA) as π-conjugated ligands and Ni2+ as metallic centers, which exhibits a unique two-dimensional nanosheet-like structure with available active sites, sufficient electrochemical activity, and multi-electron redox capability. On the one hand, the as-prepared Ni-BTA coordination polymer as electrode material exhibits a rapid, reversible, and efficient energy storage behavior with a large reversible capacity of 198 mA·h·g-1 at 1 A·g-1 and a high-rate capability of 150 mA·h·g-1 at 20 A·g-1 in alkali-ion aqueous electrolyte, which are further demonstrated by the in-situ Raman investigation. On the other hand, the Ni-BTA coordination polymer as anti-corrosion additive was introduced into the epoxy resin to achieve a Ni-BTA epoxy coating, which shows a long-term anti-corrosion performance with a low corrosion rate of 4.62×10-6 mm·a-1 and a high corrosion inhibition efficiency of 99.86%, suggesting its great engineering potential as the bi-functional organic material for high-performance energy storage and corrosion protection.
    Towards understanding the mechanism of n-hexane tolerance in Synechocystis sp. PCC 6803
    Tao Sun, Shubin Li, Guangsheng Pei, Lei Chen, Weiwen Zhang
    2023, 59(7):  128-134.  doi:10.1016/j.cjche.2022.11.015
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    Synthetic biology efforts have also led to the development of photosynthetic cyanobacteria as “autotrophic cell factories” for biosynthesis of various biofuels directly from CO2. However, the low tolerance to toxicity of biofuels has restricted the economic application of cyanobacterial hosts. In this study, RNA-seq transcriptomics was employed to reveal stress responses to exogenous n-hexane in Synechocystis sp. PCC 6803. Functional enrichment analysis of the transcriptomic data showed that signal transduction systems were induced significantly. To further identify regulatory genes related to n-hexane tolerance, a library of transcriptional regulators (TRs) deletion mutants was then screened for their roles in n-hexane tolerance. The results showed that a knockout mutant of slr0724 that encodes an HtaR suppressor protein was more tolerant to n-hexane than the wild type, indicating the involvement of slr0724 in n-hexane tolerance. This study provides the foundation for better understanding the cellular responses to n-hexane in Synechocystis sp. PCC 6803, which could contribute to the further engineering of n-hexane tolerance in cyanobacteria.
    A dynamic control structure of liquid-only transfer stream distillation column
    Borui Liu, Tao Zhang, Yi Zheng, Kailong Li, Hui Pan, Hao Ling
    2023, 59(7):  135-145.  doi:10.1016/j.cjche.2022.12.009
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    The intention of this fundamental work is to explore the manipulation of a mixture of benzene, toluene and o-xylene separated from liquid-only transfer divided-wall column (LTS-DWC). First, two control structures are clearly proposed, including seven component control loops (CS1) and seven temperature control loops (CS2). However, two control structures can handle ±10% feed disturbances rather than larger feed disturbances. Subsequently, an equivalent four-column model by introducing withdraw ratio is developed to discuss the effect of two liquid-only side-stream on the overall reboiler duty. It is indicated that the second liquid-only side-stream withdraw ratio strongly affects the overall energy consumption. Hence, six-component control loops within the fixed second liquid-only side-stream withdraw ratio (CS3) is proposed and the purity of products returns to set value even as facing ±20% feed disturbances. Finally, based on the above results, it is established a temperature control structure (CS4) for controlling fixed second liquid-only side-stream withdraw ratio, which can cope with ±15% disturbances. Inspired by these findings, an insight into the dynamic control of LTS-DWC promotes the industrial implementation of DWC through new liquid-only side-stream configurations.
    Crystalline-magnetism action in biomimetic mineralization of calcium carbonate
    Chaoqun Wu, Xun Liu, Fujun Yao, Xin Yang, Yan Wang, Wenyuan Hu
    2023, 59(7):  146-152.  doi:10.1016/j.cjche.2023.01.004
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    The influence of minor environmental factors, such as the geomagnetic field, on the biomineralization of nacres, is often ignored but a great deal of research has confirmed its important role in the normal mineralization of calcium carbonate. Although the geomagnetic field is weak, its cumulative effects need to be considered given that the biomineralization process can take years. Accordingly, the authors of this paper have investigated the effects of weak magnetic fields (25 Gs or 50 Gs) on calcium carbonate mineralization and analyzed the mechanism involved. The results show that even a weak magnetic field conduces to the formation of vaterite or aragonite, in the induction order of precursor → vaterite → aragonite. The stronger the magnetic field and the longer the time, the more obvious the induction effect. The effect of a magnetic field is strongest in the aging stage and weakest in the solution stage. Inductions by egg-white protein and by a magnetic field inhibit each other, but they both restrict particle growth. These findings highlight the importance of minor environmental factors for biomineralization and can serve as a reference for biomimetic preparation of a CaCO3 nacre-like structure and for anti-scale technology for circulating cooling water.
    Experimental investigation of the mixing efficiency via intensity of segregation along axial direction of a rotating bar reactor
    Abdelgadir Bashir Banaga, Yan-Bin Li, Zhi-Hao Li, Bao-Chang Sun, Guang-Wen Chu
    2023, 59(7):  153-159.  doi:10.1016/j.cjche.2023.01.003
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    As a significant index to evaluate the mixing efficiency, studying the concentration distribution is directly related to the intensity of segregation (Is). In this work, the Is of the mixture composed of NaCl solution-water was investigated experimentally in a rotating bar reactor (RBR) by the conductivity method. The results showed that the mixing efficiency was improved along the axial direction from the bottom to the top in the RBR. The concentration distribution at the bottom section was more uneven, and Is was higher compared with the top section, which decreased from 6.53×10-5 to 1.57×10-7. With the increase of rotational speed from 0 to 700 r·min-1, Is at the bottom and top sections decreased from 4.27×10-3 to 7.10×10-5 and from 1.93×10-3 to 7.29×10-7, respectively. The increases flow rate of solution A, and the decreases of concentration of NaCl and flow rate of solution B gave rise to the reduction of Is, signifying an improved mixing efficiency. The results revealed that the conductivity method used in this paper has high efficiency and low cost to measure the, which indicates a promising prospect for estimating reactors’ mixing performance.
    Enhancing effect of choline chloride-based deep eutectic solvents with polyols on the aqueous solubility of curcumin-insight from experiment and theoretical calculation
    Wen Yu, Yiyang Bo, Yiling Luo, Xiyan Huang, Rixiang Zhang, Jiaheng Zhang
    2023, 59(7):  160-168.  doi:10.1016/j.cjche.2023.01.005
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    The development of green solvents for enhancing aqueous solubility of drug curcumin remains a challenge. This study explores the enhancing effect of deep eutectic solvents (DESs) on the aqueous solubility of curcumin (CUR) via experiment and theoretical calculation. Choline chloride-based DESs with polyols 1,2-propanediol (1,2-PDO), 1,3-propanediol, ethylene glycol, and glycerol as hydrogen bond donors were prepared and used as co-solvents. The CUR aqueous solubility increased with increasing the DESs content at temperature of 303.15-318.15 K, especially in aqueous ChCl/1,2-PDO (mole ratio 1:4) solutions. The positive apparent molar volume values and reduced density gradient analysis confirmed the existence of strong interactions between CUR and solvent. The van der Waals interactions and hydrogen bonding coexisted in DESs monomer retained the stability of DESs structure after introducing CUR. Moreover, the lower interaction energy of DESs…CUR system than that of the counterpart DESs further proved the strong interaction between CUR and DESs. The lowest interaction energy of ChCl/1,2-PDO…CUR system indicated that this system was the most stable and ChCl/1,2-PDO was promising for CUR dissolution. This work provides efficient solvents for utilizing curcumin, contributing to a deep insight into the interactions between DES and CUR at the molecular level, and the role of DESs on enhancing drugs solubility.
    Influence of the electrolyte conductivity on the critical current density and the breakdown voltage
    Hae-Kyun Park, Dong-Hyuk Park, Bum-Jin Chung
    2023, 59(7):  169-175.  doi:10.1016/j.cjche.2023.01.007
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    The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis (CGDE) in a water electrolysis. Critical current density (CCD) and breakdown voltage were measured together with in situ observation of hydrogen bubble behavior, whose influence has not been focused on. For a fixed current during normal electrolysis, hydrogen coalescence adjacent to cathode surface was invigorated at a lower conductivity. Photographic analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen bubbles. The CCD increased about 104% within given range of conductivity (11.50-127.48 mS·cm-1) due to impaired bubble coalescence, which delays hydrogen film formation on the cathode. Meanwhile, decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%. It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors, whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.
    Effects of ion-exchange on the pervaporation performance and microstructure of NaY zeolite membrane
    Meihua Zhu, Xingguo An, Tian Gui, Ting Wu, Yuqin Li, Xiangshu Chen
    2023, 59(7):  176-181.  doi:10.1016/j.cjche.2022.12.006
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    Pervaporation performance of NaY zeolite membranes is improved by ion-exchange with di-valent nitrate salt. Different nitrate salts, including Co(NO3)2, Mg(NO3)2, Zn(NO3)2, Ca(NO3)2, Cu(NO3)2, KNO3, and AgNO3, have great effects on the channel structure and water affinity of the NaY zeolite membrane. When the concentration of nitrate salt, ion-exchange temperature and time are 0.1 mol·L-1, 50 ℃ and 2 h, the ion-exchange degree order of NaY zeolites is Ag+ > K+ > Ca2+> Zn2+ ≫ Co2+ > Mg2+. Especially, Ag+ and K+ cation exchange degree of NaY zeolites are achieved to 96.54% and 82.77% in this work. BET surface, total pore capacity, pore size distribution and water contact angle of the ion-exchanged NaY zeolites are all disordered by mono- and di-valent cations. Di-valent nitrate salt is favor for increasing the dehydration performance of NaY zeolite membranes by ion-exchange. When the ion-exchange solution is Zn(NO3)2, the total flux variation and separation factor variation of the NaY membrane (M-5) are -45% and 230% for separation of 10% (mass) H2O/EtOH mixture by pervaporation, and the ion-exchanged membranes showed good reproducibility.
    Optimization of decoupling combustion characteristics of coal briquettes and biomass pellets in household stoves
    Jian Han, Xinhua Liu, Shanwei Hu, Nan Zhang, Jingjing Wang, Bin Liang
    2023, 59(7):  182-192.  doi:10.1016/j.cjche.2022.12.012
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    Burning coal briquettes or biomass pellets in household decoupling stoves is of significance to the reduction of residential pollutant emissions such as NO and CO. In order to make full use of the superiority of decoupling combustion technology, the household stoves should be specially designed and optimized to adapt to fuel types and combustion characteristics. Using numerical simulation and experimental validation, this study quantitatively clarified that the reducibility of devolatilization char plays an important role in the suppression of NO emission in the decoupling combustion of coal, while the reducibility of pyrolysis gases has a dominant effect on the reduction of NO in the decoupling combustion of biomass. An optimal parameter combination of throat height and grate angle was obtained for the simultaneous suppression of NO and CO emissions in the household decoupling stove burning coal briquettes. Two types of decoupling stoves were developed to enable the clean combustion of biomass pellets. The A-type biomass stove with a multi-pass smoke tunnel shows a better comprehensive NO and CO reduction effectiveness than the B-type biomass stove consisting of a two-stage grate structure and an S-shaped pyrolysis chamber. The optimal structural parameters provided references for the design and manufacture of commercial decoupling coal and biomass stoves.
    Nitrogen and phosphorus co-doped activated carbon induces high density Cu+ active center for acetylene hydrochlorination
    Fei Li, Xuemei Wang, Pengze Zhang, Qinqin Wang, Mingyuan Zhu, Bin Dai
    2023, 59(7):  193-199.  doi:10.1016/j.cjche.2023.01.017
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    This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination. Cu-based catalysts supported by NP co-doped activated carbon (AC) with different content (mCu-xNP/AC) were manufactured and applied in the acetylene hydrochlorination reaction. It was found that the doping of carriers N and P induced the transformation of Cu2+ to Cu+, and the catalytic activity was markedly improved. Under the optimal reaction temperature of 220 ℃, the gas hourly space velocity (GHSV) of C2H2 was 90 h-1 and VHCL : VC2H2 was 1.15. The initial activity of the 5%Cu-30NP/AC catalyst reached 95.59%. Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon, which increased the ratio of Cu+/Cu2+. The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C2H2 decreased slightly, and the chemisorption capacity for HCl increased significantly, which was the reason for the increased activity of the catalyst. The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.
    Synthesis of porous carbon nanomaterials and their application in tetracycline removal from aqueous solutions
    Sufei Wang, Mengjie Hao, Danyang Xiao, Tianmiao Zhang, Hua Li, Zhongshan Chen
    2023, 59(7):  200-209.  doi:10.1016/j.cjche.2022.12.014
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    The low-cost and efficient elimination of tetracycline from wastewater and to decrease the concentration in soils, sediments, rivers, underground water, or lakes are crucial to human health. Herein, three-dimensional porous carbon nanomaterials were synthesized using glucose and NH4Cl by sugar-blowing process at 900 ℃ and then oxidized under air atmosphere for surface functional group modification. The prepared 3D porous carbon nanomaterials were applied for the removal of tetracycline from aqueous solutions. The sorption isotherms were well simulated by the Langmuir model, with the calculated sorption capacity of 2378 mg·g-1 for C-450 at pH = 6.5, which was the highest value of today’s reported materials. The porous carbon nanomaterials showed high stability at acidic conditions and selectivity in high salt concentrations. The good recycle ability and high removal efficiency of tetracycline from natural groundwater indicated the potential application of the porous carbon nanomaterials in natural environmental antibiotic pollution cleanup. The outstanding sorption properties were attributed to the structures, surface areas and functional groups, strong interactions such as H-bonding, π-π interaction, electrostatic attraction, etc. This paper highlighted the synthesis of porous carbon nanomaterials with high specific surfaces, high sorption capacities, stability, and reusability in organic chemicals’ pollution treatment.
    Measurement and model of density, viscosity, and hydrogen sulfide solubility in ferric chloride/trioctylmethylammonium chloride ionic liquid
    Zhonghao Li, Yuanyuan Yang, Huanong Cheng, Yun Teng, Chao Li, Kangkang Li, Zhou Feng, Hongwei Jin, Xinshun Tan, Shiqing Zheng
    2023, 59(7):  210-221.  doi:10.1016/j.cjche.2022.11.012
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    The density and viscosity of ferric chloride/trioctylmethylammonium chloride ionic liquid (rFeCl3/[A336]Cl) with different molar ratios (r = 0.1-0.8) of FeCl3 to [A336]Cl were measured at temperatures from 313.15 to 358.15 K and atmospheric pressure. The density and viscosity data were fitted by the relevant temperature variation equations, respectively. The variation of density and viscosity with temperature and r was obtained. The solubility of rFeCl3/[A336]Cl to H2S was measured at temperatures from 318.15 to 348.15 K and pressures from 0 to 150 kPa. The effects of temperature, pressure, and r on the solubility of H2S were discussed. The reaction equilibrium thermodynamic model (RETM) was used to fit the H2S solubility data, and the average relative error was less than 1.3%, indicating that the model can relate the solubility data well. And Henry's constant and chemical reaction equilibrium constant were obtained by the RETM fitting. The relationships of Henry's constant and chemical reaction equilibrium constant with temperature and r were analyzed.
    Mass-producible low-cost flexible electronic fabrics for azo dye wastewater treatment by electrocoagulation
    Chaoyi Yin, Jingyuan Ma, Jian Qiu, Ruifang Liu, Long Ba
    2023, 59(7):  222-230.  doi:10.1016/j.cjche.2023.02.011
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    Electrocoagulation is progressively becoming an ecologically friendly water treatment method owing to its lack of secondary pollution, high active ingredient concentration, high treatment effectiveness, simple equipment, and simplicity of automated control implementation. Herein, electrocoagulation is offered as a method for treating wastewater containing azo dyes using a revolutionary flexible electronic fabric that can be mass-producible at a reasonable price. A computer-controlled machine embroiders 316L stainless steel fiber (316L SSF) onto an insulating fabric to manufacture a flexible electronic device of cathode and anode with a monopolar arrangement on the fabric surface. Using methyl orange (MO) solution to simulate azo dye wastewater, the decolorization rate of 500 ml MO reached 99.25% under the conditions of 50 mg·L-1 initial mass concentration, 120 min electrolysis time, 15 mA·g-1 current density, 1 cm electrode spacing, 0.1 mol·L-1 NaCl, pH 7.6, 200 r·min-1 rotational speed of the stirrer, and 22-25 ℃ room temperature. In addition, it is feasible to embroider flexible electronic fabrics with varied sizes and numbers of electrodes based on the amount of treated sewage to increase the degradation rate, which has significant practical application value.
    Minimax entropy-based co-training for fault diagnosis of blast furnace
    Dali Gao, Chunjie Yang, Bo Yang, Yu Chen, Ruilong Deng
    2023, 59(7):  231-239.  doi:10.1016/j.cjche.2022.12.007
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    Due to the problems of few fault samples and large data fluctuations in the blast furnace (BF) ironmaking process, some transfer learning-based fault diagnosis methods are proposed. The vast majority of such methods perform distribution adaptation by reducing the distance between data distributions and applying a classifier to generate pseudo-labels for self-training. However, since the training data is dominated by labeled source domain data, such classifiers tend to be weak classifiers in the target domain. In addition, the features generated after domain adaptation are likely to be at the decision boundary, resulting in a loss of classification performance. Hence, we propose a novel method called minimax entropy-based co-training (MMEC) that adversarially optimizes a transferable fault diagnosis model for the BF. The structure of MMEC includes a dual-view feature extractor, followed by two classifiers that compute the feature’s cosine similarity to representative vector of each class. Knowledge transfer is achieved by alternately increasing and decreasing the entropy of unlabeled target samples with the classifier and the feature extractor, respectively. Transfer BF fault diagnosis experiments show that our method improves accuracy by about 5% over state-of-the-art methods.
    Intensified shape selectivity and alkylation reaction for the two-step conversion of methanol aromatization to p-xylene
    Tingjun Fu, Ran Wang, Kun Ren, Liangliang Zhang, Zhong Li
    2023, 59(7):  240-250.  doi:10.1016/j.cjche.2023.02.021
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    Two-step conversion of methanol to aromatics via light hydrocarbons can significantly improve the conversion stability compared with direct aromatization of methanol, but it remains a challenge to achieve a high p-xylene (PX) selectivity. Herein, silica coating was firstly used to passivate external acid sites of ZSM-5 catalyst for the aromatization of light hydrocarbons by the chemical liquid deposition method. With the increase of SiO2 deposition, the density of the external acid sites of the catalyst was decreased from 0.1 to 0.03 mmol·g-1, which inhibited the surface secondary reactions and increased the PX/X from 34.6% to 60.0%. In view of the fact that the aromatization process in the second step was partly inhibited as methanol was consumed in advance in the upper methanol-to-light hydrocarbons catalyst layer, part of methanol was directly introduced into the lower aromatization catalyst layer to promote the alkylation process during the aromatization, which decreased the toluene selectivity from 34.5% to 14.3% but increased the xylene selectivity from 40.0% to 55.3%. It was also found that an appropriate external acid density was needed for aromatization catalyst to strengthen the alkylation process and improve the selectivity of xylene under the conditions of methanol introduction.
    The calculation and optimal allocation of transmission capacity in natural gas networks with MINLP models
    Yaran Bu, Changchun Wu, Lili Zuo, Qian Chen
    2023, 59(7):  251-261.  doi:10.1016/j.cjche.2022.12.010
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    The transmission capacity of gas pipeline networks should be calculated and allocated to deal with the capacity booking with shippers. Technical capacities, which depend on the gas flow distribution at routes or interchange points, are calculated with a multiobjective optimization model and form a Pareto solution set in the entry/exit or point-to-point regime. Then, the commercial capacities, which can be directly applied in capacity booking, are calculated with single-objective optimization models that are transformed from the above multiobjective model based on three allocation rules and the demand of shippers. Next, peak-shaving capacities, which are daily oversupply or overdelivery amounts at inlets or deliveries, are calculated with two-stage transient optimization models. Considering the hydraulic process of a pipeline network and operating schemes of compressor stations, all the above models are mixed-integer nonlinear programming problems. Finally, a case study is made to demonstrate the ability of the models.
    Oxidative exfoliation of spent cathode carbon: A two-in-one strategy for its decontamination and high-valued application
    Runze Chen, Yuran Chen, Xuemin Liang, Yapeng Kong, Yangyang Fan, Quan Liu, Zhenyu Yang, Feiying Tang, Johnny Muya Chabu, Maru Dessie Walle, Liqiang Wang
    2023, 59(7):  262-269.  doi:10.1016/j.cjche.2022.10.020
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    Spent cathode carbon (SCC) from aluminum electrolysis is a potential graphite resource. However, full use of the SCC remains a challenge, since it contains many hazardous substances (e.g., fluoride salts, cyanides), encapsulated within the thick carbon layers and thus posing serious environmental concerns. This work presents a chemical oxidative exfoliation route to achieve the recycling of SCC and the decontaminated SCC with high-valued graphene oxide (GO)-like carbon structures (SCC-GO) is applied as an excellent adsorbent for organic pollutants. Specifically, after the oxidative exfoliation, the embedded hazardous constituents are fully exposed, facilitating their subsequent removal by aqueous leaching. Moreover, benefiting from the enhanced specific surface areas along with abundant O-containing functional groups, the as-produced SCC-GO, shows an adsorption capacity as high as 347 mg·g-1 when considering methylene blue as a pollutant model, which exceeds most of the recently reported carbon-based adsorbents. Our study provides a feasible solution for the efficient recycling of hazardous carbonaceous wastes.
    Remediation of oily soil using acidic sophorolipids micro-emulsion
    Huie Liu, Hongjian Chen, Guanghui Huang, Yunfei Yu, Rujie Li, Shuang Chen
    2023, 59(7):  270-278.  doi:10.1016/j.cjche.2022.12.005
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    A sophorolipids (SLs) micro-emulsion in Winsor type I form was used for crude oil contaminated soil washing treatment. The micro-emulsion shows higher oil removal rate than SLs aqueous solution and diesel oil. The type I micro-emulsion with w(SLs) = 6%, w(NaCl) = 1%, w(diesel) = 13.36% gave a high oil removal rate of 95.6% and the eluate remained in type I state. The recovered oil showed lower viscosity, mainly caused by the entering of diesel from the micro-emulsion phase into the oil phase and the lower removal rate of the heavier components, such as the resin and asphaltene. The initial heavily saline-alkaline soil changed into mildly saline-alkaline state after washing treatment, favoring the germination and growth of plants, with ryegrass showing better germination and growth effect than alfalfa. The ryegrass showed good phytoremediation effect on the contaminated soil after SLs micro-emulsion washing. The combination process of SL micro-emulsion washing and ryegrass phytoremediation is prospective for oily soil treatment.
    Molybdenum tailored Co0/Co2+ active pairs on a perovskite-type oxide for direct ethanol synthesis from syngas
    Yi Wu, Pengfei Song, Ningyan Li, Yanan Jiang, Yuan Liu
    2023, 59(7):  279-289.  doi:10.1016/j.cjche.2023.01.018
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    Selective synthesis of ethanol from syngas under the Co-based catalysts is still challenging due to the hard of regulating the active site Co0 and Co2+ ratio. In this work, a series of CaTi0.9-xCoxMo0.1O3 (x = 0, 0.1-0.4) and CaTi0.7Co0.3O3 catalysts were prepared by using citric acid complexation method to promote the synthesis of ethanol. It was found that Mo species in the perovskite lattice can regulate the Co0 and Co2+ ratio through the domain-limiting effect of perovskite and the degree of Co reduction could be adjusted by changing the Co/Mo molar ratio. Among these investigated catalysts, the total selectivity of alcohols over the catalyst with the optimal Co/Mo ratio CaTi0.6Co0.3Mo0.1O3 reached 39.1%, with ethanol accounting for 74.7%, which was ascribed to the moderate and tightly bound ratio of dissociative to non-dissociative adsorption sites on the surface and the balance of CHx-CHy coupling and CO insertion.