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Table of Content
05 October 2020, Volume 71 Issue 10
    Reviews and monographs
    Photoelectrochemical water splitting into active hydrogen/oxygen species coupling with hydrogenation/oxidation process using layered double hydroxides-based nanocatalysts
    Tianyi LAI,Jikang WANG,Tian LI,Sha BAI,Xiaojie HAO,Yufei ZHAO,Xue DUAN
    2020, 71(10):  4327-4349.  doi:10.11949/0438-1157.20200693
    Abstract ( 262 )   HTML ( 37)   PDF (13207KB) ( 213 )  
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    Hydrogenation/oxidation processes are regarded as the most widely used catalytic reactions in modern chemical development. However, the traditional reaction process always requires harsh reaction conditions (such as high temperature, high pressure, a lot of hydrogen/oxygen consumption, etc), the high cost, overconsumption of energy and low selectivity is always limiting its further development. Therefore, conducting the hydrogenation/oxidation reaction efficiently under mild conditions is one of the greatest challenges in this field. Photoelectrocatalysis has been widely studied due to its wide, clean and sustainable energy sources, which combines the advantages of both photocatalysis and electrocatalysis. Moreover, the process of generating H2/O2 by photoelectrocatalytic water splitting involves the production of highly reactive intermediate species (active hydrogen *H and active oxygen *O) which can be used by directly coupling the hydrogenation/oxidation catalytic processes, and the efficiency of coupled reaction will be greatly improved. The review here summarizes the research progress of photoelectrocatalysis from three aspects: active species of intermediate products produced by photoelectrochemical water splitting, hydrogenation/oxidation reaction of the traditional chemical industry, and coupling photoelectrochemical water splitting with hydrogenation/oxidation process using layered double hydroxides (LDHs)-based nanomaterials. It is expected to provide ideas for the high selectivity and low cost preparation of high value-added organic chemicals.

    Recent advances of numbering-up technology of micro-dispersion devices
    Yongjin CUI, Yankai LI, Kai WANG, Jian DENG, Guangsheng LUO
    2020, 71(10):  4350-4364.  doi:10.11949/0438-1157.20200561
    Abstract ( 165 )   HTML ( 10)   PDF (4095KB) ( 140 )  
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    Monodisperse droplets are templates for producing spherical particles and microcapsules, and related materials are widely used in optical display, drug delivery, bioassay, food processing and other fields. Micro-dispersion technology is a recognized new method to obtain microdroplets with tiny size, narrow particle size distribution and controllable structure by accurately controlling the multiphase flow in microchannels. However, due to the low throughput of a single microchannel, its large-scale industrial and commercial applications are seriously limited. To achieve high-throughput and easy-to-control production, it is the basic numbering-up strategy of micro-dispersion devices by parallelizing a large number of microdroplet generators and the network of fluid distribution channels onto a single chip. To maintain the monodispersity of droplets and the robustness of device, the uniform distribution of fluid in parallel microchannels is a key scientific issue. This paper systematically reviews the recent progress in the numbering-up technology of micro-dispersion devices. The manufacturing technologies and materials are analyzed. On this basis, the future research directions of numbering-up of micro-dispersion devices are prospected.

    Recent progress in preparation of functional capsule membranes based on co-extrusion minifluidic technique
    Wenying LIU, Xiaojie JU, Rui XIE, Wei WANG, Zhuang LIU, Liangyin CHU
    2020, 71(10):  4365-4378.  doi:10.11949/0438-1157.20200445
    Abstract ( 127 )   HTML ( 7)   PDF (4830KB) ( 86 )  
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    As a kind of encapsulation system, the capsule membrane has a unique internal cavity structure, which can encapsulate and protect active substances and is widely used in the fields of substance encapsulation and controlled release of drugs. Capsule membranes fabricated with calcium alginate (Ca-Alg) as shells process notable advantages such as good biocompatibility and degradability. Compared with other fabrication methods, co-extrusion minifluidic technique has the advantages of facile fabrication process and mild conditions for fabrication of Ca-Alg capsule membranes with uniform size and regulated structures. This paper reviews recent progress in fabrication and functionalization of Ca-Alg capsule membranes by co-extrusion minifluidic technique. Fabrication of Ca-Alg capsule membranes with single and multi-compartment, factors affecting mass transfer of Ca-Alg capsule membranes, encapsulation of cells for producing multicellular spheroids and investigating the mechanics of tumor progression in vitro with three-dimensional environments, and functionalization of Ca-Alg capsule membranes by addition of functional materials with thermo and pH-responsive switching functions are highlighted. This review provides guidance for the further design and fabrication of novel capsule membranes as well as their applications in enzyme catalytic reactions, immobilizations of cells and foods, and controlled release of chemicals.

    Application of ionic liquid in extraction and separation of rare earth
    Daoguang WANG, Junfeng WANG, Xiangping ZHANG, Yilin WANG, Xiaofei ZHANG
    2020, 71(10):  4379-4394.  doi:10.11949/0438-1157.20200677
    Abstract ( 156 )   HTML ( 4)   PDF (2454KB) ( 135 )  
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    The extraction and separation of rare earth elements is one of the key steps to obtain high-purity single rare earths. The development of new materials and new processes with high-efficiency separation capabilities for rare earth elements is a hot spot for scientific and technological workers worldwide. As a representative new material, ionic liquid has unique physical and chemical properties such as non-volatile, non-flammable, good stability, and adjustable structural properties. In recent years, its application in the field of rare earth element extraction and separation has received extensive attention.This paper provides a systematical review of the publications in recent years reporting the application of ILs in extraction and separation of rare earth (RE) that is essential to obtain high-purity RE products. The ILs-based extraction and separation by use of non-functional and/or functional ILs were here reviewed and discussed in terms of extraction/stripping behaviors, separation performance and mechanisms. The challenges and future directions for the development and application of ILs-based extraction on RE separation were discussed finally.

    Research status and development trend of artificial antibacterial fibers
    Le ZHOU, Binqi WANG, Yi NIE
    2020, 71(10):  4395-4408.  doi:10.11949/0438-1157.20200633
    Abstract ( 104 )   HTML ( 2)   PDF (5464KB) ( 108 )  
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    With the improvement of people??s awareness of environmental protection and health, the demand for antibacterial technology in the fiber textile market is increasing. Artificial antibacterial fibers are composite fibers with antibacterial function prepared by adding antibacterial agents into common fiber, which is simple and convenient to industrial production and application. Antibacterial agent is the key component in the preparation of artificial antibacterial fibers, which determines the preparation method and antibacterial effect of antibacterial fibers. The research status of inorganic antibacterial agents, organic antibacterial agents, natural antibacterial agents and new material antibacterial agents used in the preparation of artificial antibacterial fibers were mainly discussed and reviewed, and the research focus and development trend of artificial antibacterial fibers in the future were prospected.

    Advances in single-atom catalysts for oxygen electrodes
    Yao WANG,Yiyun TANG
    2020, 71(10):  4409-4428.  doi:10.11949/0438-1157.20190615
    Abstract ( 122 )   HTML ( 13)   PDF (5240KB) ( 96 )  
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    As the most promising energy conversion and storage devices, fuel cells and metal-air batteries are of great benefit in alleviating the energy and environmental problems. However, the sluggish oxygen electrode reactions, including oxygen reduction reaction (ORR) for fuel cell and ORR couple with oxygen evolution reaction (OER) for zinc-air batteries, seriously limit the efficient of both types of devices. In recent years, single-atoms catalysts (SACs) have been proposed to improve the kinetics of oxygen electrode reaction. Therefore, for these two types of oxygen electrode reactions, this review firstly summarized their possible mechanism. Then, the SACs were classified by the different metal elements for both ORR and OER. Thus, noble-metal-based and non-noble-metal-based catalysts have been summarized in these two reactions. At the same time, a summary of the dual-function catalyst and its application in zinc air batteries is also given. Finally, in view of the current problems and future development directions of SACs, suggestions are put forward, aiming to pave the way for the design and development of monoatomic oxygen electrode catalysts.

    Recent progress on cathode materials for potassium-ion batteries
    Zhibo ZHANG, Kunyao PENG, Maoning GENG, Xinyue ZHAO, Si LIU, Changbao ZHU
    2020, 71(10):  4429-4444.  doi:10.11949/0438-1157.20200612
    Abstract ( 137 )   HTML ( 13)   PDF (5625KB) ( 108 )  
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    Due to resource and cost advantages, as well as the similarity of working principles with lithium-ion batteries, potassium-ion batteries (PIBs) have a bright future in large-scale energy storage applications. However, the ion size of potassium is larger than that of lithium and sodium ions, which not only affects the transport in the electrode, but also tends to cause irreversible damage to electrode structure, resulting poor electrochemical performance. For PIBs, the graphite that already applied in lithium-ion batteries can be used as anode, thus the cathode materials are the key to develop the high-performance potassium ion batteries. This review summarized the progress of various types of cathode materials for PIBs, and discussed their advantages, problems and corresponding modification methods. Finally, the main challenges and perspectives are also discussed to provide the future direction of cathode materials for PIBs.

    Constructing and regulating electrocatalysts: from perspective of mesoscale
    Xingqun ZHENG, Li LI, Zidong WEI
    2020, 71(10):  4445-4461.  doi:10.11949/0438-1157.20200739
    Abstract ( 90 )   HTML ( 7)   PDF (10845KB) ( 70 )  
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    The electrocatalyst is the core of the electrochemical reaction in the chemical energy conversion process. It is of great significance to improve the electrocatalytic efficiency, save energy and reduce consumption by maximizing its catalytic performance. Guaranteeing almost all active sites of catalysts on the cross of various channels, regulating the intrinsic activity, as well as improving conductivity and stability are of great significance for designing and optimizing electrocatalysts and maximizing their performance. Along with modulation of electrocatalysts, there is a nonlinear relationship among the changes of structure, composition and properties of catalysts, which shows mesoscale characteristics, that is, entirely new characteristics which is different from that of the two extreme cases. This review summarizes the mesoscale phenomena and effects in constructing and modulating active sites of electrocatalysts. It covers the mesoscale phenomenain terms of crystal structure, chemical composition, phase interface and strain effects in tuning structure and performance of electrocatalysts. It is interesting to gain insight into mesoscale mechanisms which opens a fresh perspective to optimal and tunable design and preparation of electrocatalysts, and thus supply copious novel ideas for forming a new theory system for electrochemical catalysis.

    Research advances in deep learning based quantitative structure-property relationship modeling of solvents
    Luyao TIAN, Zihao WANG, Yang SU, Huaqiang WEN, Weifeng SHEN
    2020, 71(10):  4462-4472.  doi:10.11949/0438-1157.20200814
    Abstract ( 104 )   HTML ( 7)   PDF (2060KB) ( 84 )  
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    Quantitative structure-property relationship is an important theoretical basis for the design and development of solvent molecules. The establishment of an accurate and reliable prediction model can effectively solve the problems of limited property database resources, large human and material resources consumption and dangerousness in the experimental process. With the rapid development of artificial intelligence technology, deep learning has made some breakthroughs in chemical industry. In this context, this work reviews the research theories and methods of classical and intelligent modeling, and introduces some advances of deep learning in intelligent modeling on large-scale data. In addition, the advantages and application prospects of deep learning techniques in the prediction of various basic physical properties as well as potential impacts on environment, health and safety of organics are elaborated. From the angle of the intelligent development of green solvents, the prospects of theoretical and application researches on quantitative structure-property relationship based on deep learning are outlined in the development of chemical product and process.

    Research on synthesis and application of metal-organic frame composites in supercapacitors
    Yanqin XU, Liyue XIAO, Yuan CAO, Changguo CHEN, Dan WANG
    2020, 71(10):  4473-4490.  doi:10.11949/0438-1157.20191596
    Abstract ( 122 )   HTML ( 4)   PDF (10805KB) ( 57 )  
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    Electrode material is a key component of supercapacitors (SCs). As a porous material, metal-organic frameworks (MOFs) have attracted much attention in the field of SCs electrode materials due to their high specific surface area, controllable structure, and adjustable pore size. The low conductivity and stability of MOFs are still the main challenges in practical applications. MOF composite materials are a type of composite materials composed of MOFs and one or more different materials. They can effectively combine the advantages of MOFs with the advantages of other functional materials, such as excellent electrical conductivity and unique electrochemical properties. Therefore, MOF composite materials can achieve high reversible capacity and excellent cycle performance, overcome the shortcomings of MOFs materials, and have broad application prospects in the field of SCs electrode materials. According to the dimensional classification of the materials combined with MOFs, they can be divided into four types of composite materials: 0D, 1D, 2D, and 3D MOFs. The composition and synthesis methods of these four types of composite materials are reviewed. The application of MOF composite materials in the field of SCs is systematically introduced. Furthermore, its development prospects are prospected.

    Mesoscopic strategies and molecular design of diaphragm for electrochemical reactors
    Cunpu LI, Jianchuan WANG, Zidong WEI
    2020, 71(10):  4490-4501.  doi:10.11949/0438-1157.20200759
    Abstract ( 183 )   HTML ( 7)   PDF (5007KB) ( 106 )  
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    The diaphragm material in the electrochemical reactor is a special material that separates the positive electrode and the negative electrode on the electronic path but keeps the ion transport path open. As one of the three critical materials in the electrochemical reactor, the separating diaphragm must be stable in the crucial acidic/basic, strong electric field strength, and other complex micro-environments. In this review, we focus on the molecular design of the separating diaphragm inside the electrochemical reactors. The mesoscopic strategies to regulate electrochemical properties and chemical stabilities of the separating diaphragm were discussed. The purpose of this review is to set up a link between the molecular structure of the separating diaphragm and the performances of the electrochemical reactors in terms of mesoscopic strategies.

    Progress of superhydrophobic porous materials
    Li CHEN, Cailong ZHOU, Jingcheng DU, Wei ZHOU, Luxi TAN, Lichun DONG
    2020, 71(10):  4502-4519.  doi:10.11949/0438-1157.20191305
    Abstract ( 253 )   HTML ( 15)   PDF (10073KB) ( 204 )  
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    Porous materials such as metal organic framework materials (MOFs), covalent organic framework materials (COFs), organic porous polymers (POPs), etc., have been used widely used in the fields of separation, catalysis, gas storage and drug release due to their diversity, designability, controllability and functionalization of pores. Despite these promising applications, some of the porous materials suffer from moisture-sensitivity and instability in aqueous media due to their inherent structural features. To overcome this problem, endowing them with hydrophobicity is an effective strategy. However, designing superhydrophobic porous materials has certain challenges. In this work, the progress of MOFs, COFs and POPs with (super-)hydrophobic property is introduced. Issues related to their design strategy, structures, and practical applications such as catalysis, oil/water separation and gas storage and separation were analyzed. Additionally, the current problems and the future research directions of the hydrophobic porous materials were discussed.

    Application of synthetic biology in manufacture of bio-based plastics
    Yanqin XU, Xizhi YANG, Ruoshi LUO, Yuhong HUANG, Feng HUO, Dan WANG
    2020, 71(10):  4520-4531.  doi:10.11949/0438-1157.20200214
    Abstract ( 132 )   HTML ( 6)   PDF (2437KB) ( 62 )  
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    Synthetic biology is a new discipline that uses engineering ideas as a guide to transform and reconstruct natural biological genomes, synthesize new biological components, construct new metabolic routes, and produce novel products or obtain new phenotypes. Bio-based plastics are plastics produced under the action of microorganisms or the chemical reactions using natural materials as raw materials. The usage of synthetic biology to construct engineered strains to produce bio-based plastics has become a hot topic in academia and industry. This paper reviews the development of synthetic biology and important techniques in the field of synthetic biology, focusing on the research progress in the field of metabolic pathways and engineering optimization for the construction of bio-based plastic polymer monomers and derivatives such as polyhydroxyalkanoate, nylon, polylactic acid, and butylene glycol succinate using synthetic biological techniques.

    Bio-inspired fog harvesting materials: from fundamental research to promotional strategy
    Wei ZHOU, Li CHEN, Jingcheng DU, Luxi TAN, Lichun DONG, Cailong ZHOU
    2020, 71(10):  4532-4552.  doi:10.11949/0438-1157.20200454
    Abstract ( 164 )   HTML ( 5)   PDF (23888KB) ( 86 )  
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    Nowadays, the water crisis has seriously affected people??s daily life due to water pollution and the increasing shortage of fresh water. Capturing water from the morning fog can relieve water shortages in dry areas. Inspired by the spontaneous fog trapping of Namib desert beetles, cacti, spider silk, and other animals or plants, various bionic fog collection materials with special wetting properties have been constructed by researchers. This review summarizes the latest research progress of bio-inspired fog harvesting materials in detail, discusses the design and preparation method of constructing bionic water collection materials from the four major bio-inspired strategies of fog collection, and introduces the design schemes to improve the efficiency of fog harvesting. Furthermore, the problems existing in the current bionic water collection process are analyzed, and the development trend of the materials in the future is forecasted.

    Strategies for tuning porous structures of air electrode in fuel cells
    Wenjing ZHANG, Jing LI, Zidong WEI
    2020, 71(10):  4553-4574.  doi:10.11949/0438-1157.20200750
    Abstract ( 84 )   HTML ( 6)   PDF (19057KB) ( 62 )  
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    A fuel cell is a device that converts chemical energy into electrical energy. The design of the catalytic layer of the air electrode must not only include abundant and easily accessible reactive sites, but also have highly connected electrons, protons, and reactant and product mass transfer channels.Thus the electrodes should hold specific three-dimensional geometrical structures and well-arranged functional channels to ensure accessibility of the active sites and continuous electrochemical reaction. Recently, a range of strategies have been reported to construct various porous structures for electrocatalysts of oxygen reduction reaction, including templating method, high temperature induced phase transition method, combined templating and phase transition method, and the pore-making method based on metal-organic-framework materials. The latest progresses in this field are reviewed in this article.

    Research advances in thermally coupled intensification technology for special distillation
    Shirui SUN, Ao YANG, Tao SHI, Weifeng SHEN
    2020, 71(10):  4575-4589.  doi:10.11949/0438-1157.20200757
    Abstract ( 100 )   HTML ( 2)   PDF (3692KB) ( 92 )  
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    In the production and separation process of petroleum, medicine, chemical industry and other industries, it is often accompanied by the production of azeotropic or similar boiling point mixtures. Its high-efficiency and energy-saving separation is a prerequisite for industrial clean production and sustainable development. Special distillation as an effective separation method attracts substantial attention from researchers. However, special distillation is a process with high-energy consumption. Therefore, the development of intensification technology for special distillation with low costs and reliable performance is of great significance for the economy and energy sustainable development. According to the heat and mass transfer laws of special distillation, this work introduces the research advances of thermally coupled distillation, dividing wall column, side-stream distillation, organic Rankine cycle, heat pump and different pressure thermally coupled technologies in energy saving special distillation process from the intensification principles and retrofitting technologies. In addition, this work outlines the challenge and opportunity of intensification technology to provide references of the theoretical research and application to special distillation.

    Molecular thermodynamic model for compounding of multiple surfactants
    Jin CHENG, Zhangyang CHEN, Yuming ZHANG, Qi DUAN, Cheng LIAN, Honglai LIU
    2020, 71(10):  4590-4600.  doi:10.11949/0438-1157.20200678
    Abstract ( 114 )   HTML ( 5)   PDF (1798KB) ( 81 )  
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    Surfactants are widely used in the actual industrial production. Generally, it is a compound system of multiple surfactants to make use of the characteristics of different components, so that the compound system has better performance than a single surfactant. The compounding mechanism of multiple surfactants is still an interesting topic. In this paper, experimental and theoretical models are used to study the synergistic effect among the components of mixed surfactants. Firstly, based on Flory-Huggins theory, the molecular thermodynamic model of the multi-component surfactant system is derived. The interaction parameters of the two systems are correlated through the experimental data of the binary system. The critical micelle concentration (cmc) of the multi-component system and the phase composition of the mixed surfactant micelle can be predicted. The calculated results of the three-component surfactant system model are in good agreement with the experimental values.

    Porous BN for selective adsorption of sulfur-containing compounds from fuel oil: DFT study
    Qiaoling LI, Xiaoyu WU, Xuewei WANG, Zhi XIE, Xiaofei YU, Xiaojing YANG, Yang HUANG, Lanlan LI
    2020, 71(10):  4601-4610.  doi:10.11949/0438-1157.20200359
    Abstract ( 98 )   HTML ( 5)   PDF (4069KB) ( 30 )  
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    Selective removal of sulfides in fuel oil is of great significance to the environment and human health. In this work, using density functional theory (DFT) with and without long-range dispersion correction via Grimme??s scheme (D-DFT), the adsorption behavior and adsorption selectivity of dibenzothiophene (DBT), n-hexadecane, and n-octane and toluene on the porous boron nitrides (p-BN) with/without vacancy defect have been studied. On perfect p-BN, the adsorption energy (Eads) was calculated to be 1.395, 0.600 and 0.457 eV (PBE+D) for single DBT, n-hexadecane and n-octane molecules respectively, indicating that the adsorption of DBT on p-BN is highly preferred over n-hexadecane. The strong adsorption of DBT on p-BN was attributed to the intermolecular force that derived from the interaction between the B—N polar bond and the permanent dipole of DBT molecule. With the introduction of nitrogen (VN) and boron (VB) vacancy defects, the Eads of DBT increased to 1.650 and 1.875 eV (PBE+D) and the Eads of the n-hexadecane is only 0.400 and 0.600 eV (PBE+D), respectively. The electronic structure [calculations density of states (DOS), the highest occupied molecular orbital (HOMO), total charge density together with charge density difference, and Hirshfeld charges] reveal that the chemical interactions between the defect level and S atom in sulfide enhanced the adsorption of DBT molecule on p-BN. For practical application, other sulfur-containing organic compounds including 4,6-dimethyldibenzothiophene (4,6-DMDBT), thiophene (T), benzothiophene (BT) and carbide toluene in fuel oil are also considered and p-BN still tends to selectively adsorb sulfides from carbides preferentially, suggesting that p-BN with/without vacancy defect is promising for the removal of sulfur-containing organic compounds from fuel oil. Finally, the defect formation energies were estimated to evaluate the energetic stability of defective p-BN. The growth of VN or VB strongly depends on the chemical environment. Under boron-rich conditions, the use of B2H4 as the B source is more conducive to the formation of VN than the use of B, α-B12, and BH3, etc. Contrastingly, the use of N2H4 as the N source in the nitrogen-rich environment is more beneficial to the formation of VB than the use of N2, NH3. Our results provide a useful guidance for the design and fabrication of porous BN sorbent for sulfur-containing organic matter removing from fuel oil.

    Fluid dynamics and transport phenomena
    Chaotic mixing and droplet dispersion characteristics of liquid - liquid with elastic combined impeller
    Zuohua LIU, Chuang WANG, Wei SUN, Changyuan TAO, Yundong WANG
    2020, 71(10):  4611-4620.  doi:10.11949/0438-1157.20200675
    Abstract ( 106 )   HTML ( 4)   PDF (1868KB) ( 62 )  
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    Traditional mixing and clarification tanks generally use rigid stirring blades to achieve liquid-liquid two-phase mixed extraction, which generally suffers from low efficiency and high energy consumption. A kind of elastic combined impeller was used in the mixing clarifier in this work to enhance the liquid-liquid biphase mixing behavior. Lyapunov exponent (LLE) and multiscale entropy (MSE) were used to characterize the chaotic state of the system, the particle size distribution and D32 were used to characterize the dispersion effect. The influence of impeller type (elastic combined impeller, rigid-flexible combined impeller and rigid impeller), spring length, wire diameter and outer diameter on mixing effect was studied. The results indicated that compared with the rigid impeller and the rigid-flexible combined impeller, the elastic combined impeller strengthens the energy dissipation mode of the flow field through the deformation and energy storage of the spring, improves the dispersion effect of the dispersed phase, and was conducive to the chaotic mixing of the liquid-liquid biphase. When stirring speed N = 200 r/min, the spring wire diameter was 0.6 mm, the relative length of the spring was 1.2, and the external diameter of the spring was 7 mm, the LLE value and the amplitude of MSE were the largest and the MSE values fluctuate most strongly. At the same time, there was a log-linear relationship between the D32 of dispersed phase and the stirring speed in each stirring system, and the droplet size of dispersed phase in the elastic combined impeller system was smaller and more.

    Experiment and numerical simulation of chaotic mixing performance enhanced by perturbed rigid-flexible impeller in stirred tank
    Zuohua LIU,Hongjun WEI,Xia XIONG,Changyuan TAO,Yundong WANG,Fangqin CHENG
    2020, 71(10):  4621-4631.  doi:10.11949/0438-1157.20200313
    Abstract ( 93 )   HTML ( 2)   PDF (1902KB) ( 62 )  
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    To eliminate the isolated mixing regions in the stirred tank, factors associated with chaotic mixing performance were studied, including flow field structure and fluid velocity of rigid RT impeller (R-RT), perturbed rigid RT impeller (PR-RT) and perturbed rigid-flexible RT impeller (PRF-RT). The maximum Lyapunov exponent (LLE) and multi-scale entropy (MSE) were calculated by using Matlab software programming, and the differences in flow field structure and fluid velocity of the three blade systems were studied through computational fluid mechanics. The experimental and computational results showed that perturbed rigid-flexible RT impeller could destroy the boundary of the mesostatic flow field in the isolated mixing regions and the symmetry flow in the process of fluid mixing through the random disturbance of the flexible blade, eliminating the isolated mixing regions. At 90 r/min, the LLE of the perturbed rigid-flexible RT impeller is larger than that of rigid RT impeller and perturbed rigid RT impeller. The LLE of the rigid-flexible RT impeller compared with the rigid RT impeller and perturbed rigid RT impeller increases 13.29% and 7.25% respectively and the MSE of the perturbed rigid-flexible RT impeller is also larger than that of rigid RT impeller and perturbed rigid RT impeller. The perturbed rigid-flexible RT impeller enhances the flow field instability, forms an asymmetric flow field structure, and reduces the distribution range of isolated mixing regions. The perturbed rigid-flexible RT impeller enhances the energy dissipation of the blade, improves the fluid velocity at the bottom and top of the tank and the wall of the tank, and reduces the mixing time.

    Chaotic mixing performance and mass transfer enhanced by rigid-flexible impeller with pulse jet
    Zuohua LIU, Wei SUN, Xia XIONG, Changyuan TAO, Yundong WANG, Fangqin CHENG
    2020, 71(10):  4632-4641.  doi:10.11949/0438-1157.20200303
    Abstract ( 79 )   HTML ( 2)   PDF (1461KB) ( 38 )  
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    Conventional stirred reactors generally use rigid impeller for mechanical stirring, which leads to the easy creation of isolation mixing regions in the reactor and reduces the efficiency of fluid mixing. The use of multi-flow field coupling to induce chaos and promote more fluids into a chaotic state is one of the effective ways to improve fluid mixing efficiency. In this work, the largest Lyapunov exponent(LLE) and multi-scale entropy(MSE) are investigated with the Matlab compile pressure pulsation signals. The effects of duty ratio, paddle type, flexible paddle thickness, paddle height from the bottom and pulsed air jet flow rate on the chaotic mixing of fluids in a stirred reactor under different pulse periods are explored. In addition, the effects of different impeller types, jet types and air jet flow rate on the volume oxygen mass transfer coefficient KLa are compared and analyzed. When T=0.4 s and D=80%, the results show that the LLE of the rigid-flexible RT impeller compared with the rigid RT impeller increases 11.58% and the MSE of the rigid-flexible RT impeller is also larger than that of rigid RT impeller. It was showed that the pulsed jet rigid-flexible impeller system can better enhance fluid chaos, increase the fluid mixing efficiency and homogenize the system energy distribution. In addition, pulse jet coupling RF-RT impeller system enhances the turbulent characteristics of the fluid, promotes the reduction of the thickness of the liquid film, strengthens the mass transfer and increases the KLa value of the system. When power consumption per unit volume is 360 W/m3, the KLa of the PJ-RF-RT system compared with the PT-R-RT system increases 13.46%, and the KLa of the PJ-R-RT system compared with the SJ-R-RT system increases 11.86%.

    Catalysis, kinetics and reactors
    Study on binder of extruded mordenite catalyst for dimethyl ether carbonylation
    Shouying HUANG, Xiong XIONG, Pei HE, Jianhao WANG, Ying LI, Hongkai LIU, Jing LYU, Xinbin MA
    2020, 71(10):  4642-4651.  doi:10.11949/0438-1157.20200609
    Abstract ( 73 )   HTML ( 4)   PDF (1315KB) ( 57 )  
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    The carbonylation of dimethyl ether (DME) to produce methyl acetate (MA) and the hydrogenation of MA to ethanol is a novel, green and economical ethanol synthesis route. The formation of the catalyst is of great significance to the industrialization of this process. In this paper, pseudo-boehmite and silica sol are used as binders, and mordenite molecular sieve (MOR) is extruded to prepare a series of molded MOR catalysts with different binder types and contents. By using strength evaluation and Weibull distribution analysis, we investigated the mechanical stability and reliability of the extruded MOR. Afterwards, XRD, N2-physisorption, NH3-TPD and IR spectra of pyridine adsorption were employed to explore the influence of binder on textural properties, acidity and catalytic performance. The results showed that the crystal structure of MOR was maintained after addition of binder. When the pseudo-boehmite was used as a binder, the catalyst showed the best mechanical property and catalytic activity. By establishing the quantitative relationships among the yield, TOF and structure parameter, it is found that the space time yield of MA was linearly related to the specific surface area of micropores. Meanwhile, the almost constant TOF indicated that the binders did not affect the catalytic capacity of each activesites in MOR for carbonylation of dimethyl ether.

    Effects of identities of supports on Fe-based catalyst and their consequences on activities of CO2 hydrogenation to olefins
    Yangyang LIU, Chao SUN, Malhi Haripal Singh, Chongyang WEI, Zhenzhou ZHANG, Weifeng TU
    2020, 71(10):  4652-4662.  doi:10.11949/0438-1157.20200653
    Abstract ( 189 )   HTML ( 30)   PDF (1670KB) ( 107 )  
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    The direct synthesis of olefins by CO2 hydrogenation with iron-based catalysts is one of the best ways to achieve CO2 emission reduction and CO2 conversion and utilization. At present, the CO2 hydrogenation activity and structural strength of the iron-based catalysts are still relatively low during CO2 hydrogenation process, which has become an important challenge for the industrialization of CO2 hydrogenation to olefins. In this work, a series of the supported iron-based catalyst was prepared by the impregnation method to study the influence of the properties of support materials on the structure of iron-based catalysts and the reactivities of the direct synthesis of olefins from CO2 hydrogenation. This work found that the support induced the iron species formed during the process of CO2 hydrogenation, simultaneously affected the order degree of carbon species on the surface of iron-based catalyst, and tuned the capability of CO2 adsorption and the activities of CO2 activation. The results shown that the Fe-based catalyst supported on ZrO2 exhibited the best catalytic performance for CO2 hydrogenation to olefins at 320℃ and 2.0 MPa. The CO2 conversion (>30%) and the selectivity of olefins in C2—C7 hydrocarbon products were as high as over 85%, the ratio of olefins to paraffins was 8.2, and the CO selectivity was 17.1%.

    Study on diffusion-reaction coupled strengthening mechanism based on electrosynthesis of titanium dioxide nanotube array
    Huang ZHOU, Yu CHANG, Xing FAN, Nannan ZHANG, Changyuan TAO
    2020, 71(10):  4663-4673.  doi:10.11949/0438-1157.20191292
    Abstract ( 90 )   HTML ( 5)   PDF (2975KB) ( 56 )  
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    As an excellent semiconductor material, the TiO2 is widely used in the areas of photocatalysis, solar cells, and biomedical devices. Various technologies have been established to prepare TiO2 nanotube array. These technologies mainly include numerous hydrothermal methods, template method, sol-gel method, and anodic oxidation method. Among them, the anodic oxidation method attracts much attention because of its highly ordered, uniform distribution and variable structure control. At present, the modified preparation of TiO2 nanotube array is still studied by researchers. However, basic study on the kinetic mechanism of the growth process of nanotube array is rare. Herein, we proposed the diffusion-reaction coupled strengthening mechanism based on the electrosynthesis of titanium dioxide nanotube array. Furthermore, the evolution of TiO2 nanotube array with electrolysis time was investigated, and the nonlinear dynamic mechanism of TiO2 nanotube array structure growth process was discussed in combination with SEM and electrochemical impedance analysis. It was found that the formation of TiO2 nanotube array was a self-organization behavior in the diffusion-reaction coupling process of oligomer hydroxyl titanium intermediates. Moreover, the reaction kinetics mechanism was established by analyzing the electrochemical growth mechanism, and its linear stability was analyzed. Besides, the parameter threshold space formed by the ordered structure in TiO2 nanotube array and the accompanying electrochemical oscillation were explained, and its evolution process was also discussed. After optimization, TiO2 nanotube array with ordered structure was prepared. It revealed the internal mechanism of diffusion-reaction coupling in the electrosynthesis of TiO2 nanotube array. In addition, the nonlinear dynamic mechanism proposed in this paper exists widely in the electrodissolution process of various metals, which has a significant influence on the structure formation of products and the power consumption of reaction process. This also provides a theoretical basis for strengthening the batch electrosynthesis process of new nanomaterials.

    Separation engineering
    Solubility of light alkanes and alkenes in ionic liquids
    Rui ZHANG, Shuyuan DONG, Luo WU, Zhichang LIU, Chunming XU, Haiyan LIU, Xianghai MENG
    2020, 71(10):  4674-4687.  doi:10.11949/0438-1157.20200735
    Abstract ( 106 )   HTML ( 14)   PDF (2782KB) ( 49 )  
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    The solubility of light hydrocarbons in a variety of ionic liquids was studied, and it was found that ionic liquids containing Cu(Ⅰ) had higher solubility for hydrocarbons and alkene/alkane solubility selectivity, and Et3NHCl-2.1CuCl ionic liquid was preferred. The effects of temperature and pressure on the solubility of light hydrocarbons were investigated for the selected ionic liquid. It was found that low temperature and high pressure were favorable for the dissolution of light hydrocarbons, and the alkene/alkane solubility selectivity decreased with the increase of temperature and pressure. The alkene/alkane solubility selectivity was above 8.3 at the temperature of 30℃ and the pressure of 0.2 MPa. The initial dissolution rate of hydrocarbons in ionic liquid was large, but it decreased rapidly with prolonging time, and the dissolution rate of alkenes was higher than that of alkanes at the same conditions. The alkene/alkane separation selectivity increased with decreasing content of alkenes in the mixture of alkenes and alkanes. Light hydrocarbons dissolved in ionic liquids could be desorbed by means of increasing temperature, restoring the dissolution capability of ionic liquids to hydrocarbons. Alkanes were easier to be desorbed than alkenes, and small-molecule hydrocarbons were easier to be desorbed than large-molecule hydrocarbons. The desorption percentage exceeded 92% under optimal conditions. Ionic liquid had a good reusable performance in the absorption and separation of light alkanes and alkenes. The solubility only decreased by less than 5% when it was reused five times, and the alkane/alkane solubility selectivity was basically not affected by reusing times. Software Gaussian 09 was used to study the interaction between anions of ionic liquids and light alkanes and alkanes, and the solubility difference of light alkenes and alkanes in different ionic liquids was well explained.

    Preliminary study on mechanism of confined mass transfer and separation: “secondary confinement” effect of interfacial adsorption layer
    Qingwei GAO, Yao QIN, Yumeng ZHANG, Shanshan WANG, Yudan ZHU, Xiaoyan JI, Xiaohua LU
    2020, 71(10):  4688-4695.  doi:10.11949/0438-1157.20200765
    Abstract ( 119 )   HTML ( 5)   PDF (1779KB) ( 68 )  
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    The confined mass transfer separation membrane is mainly for the high-precision separation process at the molecular/ion level, which is of great significance to solve the application needs of CO2 separation, azeotrope separation, lithium extraction from salt lake, desalination of seawater and so on. However, at present, the research of the confined mass transfer mechanism of this kind of membrane is lagging behind, and the theoretical models of confined mass transfer are lacking, which can no longer meet the needs of the rapid development of materials and chemical engineering. From the perspective of meso-science, the abnormal phenomenon of high flux and high selectivity of the confined mass transfer separation membrane is considered, that is, breaking through the trade-off effect, which is governed by compromise-in-competition between the selectivity mechanism and the flux mechanism. It is found that the fluid molecules will preferentially adsorb at the interface and form a stable adsorption layer. Based on this, the hypothesis of “secondary confinement” is put forward, that is, the surface induced new solid-like interface will have confinement effect on the intermediate fluid again. By comparing the pore size and the secondary confined size of the confined mass transfer separation membrane, the selective mechanism of the secondary confinement is further confirmed, and the quantitative prediction of the membrane flux and selectivity is preliminarily explored by combining the selective mechanism and the flux model, which may provide a theoretical basis for the precise construction of the limited area mass transfer membrane.

    Comparison of absorption efficiency of three hydrogen sulfide absorbents and optimization of absorption conditions of potassium iodate system
    Xue LYU, Yue MOU, Yiwen MIU, Hanlu LIAO, Jiansu RAN, Jie ZHENG
    2020, 71(10):  4696-4703.  doi:10.11949/0438-1157.20191151
    Abstract ( 106 )   HTML ( 4)   PDF (896KB) ( 36 )  
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    Hydrogen sulfide is corrosive and toxic, and the use of absorbents to absorb hydrogen sulfide gas is an important desulfurization treatment. The absorption efficiency of different absorbent is different. The absorption efficiency of three different hydrogen sulfide absorbent, namely ferric chloride system, potassium iodate system and alkaline potassium ferricyanide system, was firstly compared. Based on this, the absorption parameters of potassium iodate system were optimized, and the effects of concentration, temperature, pH, gas flow rate and time on the hydrogen sulfide gas absorption efficiency were discussed. The optimum absorption conditions were obtained by orthogonal test: temperature 55℃, pH 6.01, H2S flow rate 0.3 L·min-1, absorption time 1 min, the third-order absorption efficiency of 8%(mass) potassium iodate is 51.56%. The results of this study provide a theoretical reference for the absorption of hydrogen sulfide and support for the study of indirect electrolysis process.

    Molecularly imprinted materials with core-shell structure for directed desiccation
    Zhuangfei JIANG, Jiayuan HE, Rongrong MA, Qingyao LI, Lili YANG, Ling TAN, Qihui ZHANG
    2020, 71(10):  4704-4710.  doi:10.11949/0438-1157.20200210
    Abstract ( 101 )   HTML ( 6)   PDF (2002KB) ( 19 )  
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    SiO2 as the support material, methacrylic acid (MAA) as the functional monomer, azodiisobutyronitrile (AIBN) as the initiator, ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent, a surface molecularly imprinted polymer (SMIPs) material which can selectively absorb bitter substances in lemon juice was prepared. Transmission electron microscopy and infrared absorption spectroscopy were used to characterize the SMIPs, followed by adsorption capacity and selectivity studies. The results showed that SMIPs had core-shell structure, good adsorption performance (27.72 mg/g) and fast adsorption capacity (60 min). The adsorption was in accordance with the second-order kinetic model, and the adsorption process was in accordance with the Langmuir monolith adsorption model. Finally, SMIPs were used to remove the bitter substance evodine in lemon juice, and the result showed that SMIPs had good desiccation ability.

    Magnetic temperature-sensitive molecularly imprinted materials for separation and enrichment of single component of formononetin in medicinal plants
    Jiayuan HE, Zhuangfei JIANG, Rongrong MA, Lili YANG, Qingyao LI, Ling TAN, Zhitao CHEN, Qihui ZHANG
    2020, 71(10):  4711-4719.  doi:10.11949/0438-1157.20200346
    Abstract ( 60 )   HTML ( 2)   PDF (2500KB) ( 24 )  
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    The magnetic and temperature double response molecularly imprinted polymers for formononetin-specific adsorption (MTMIPs) were successfully prepared by using Fe3O4 as supporting matrix, formononetin as template, N-isopropyl acrylamide as the thermo-sensitive type functional monomer and methacrylic acid as auxiliary functional monomer. SEM, TEM, FT-IR, TGA and magnetic analysis were used to characterize the structure of MTMIPs, and then their adsorption properties and reproducibility were investigated. The results showed that MTMIPs was a core-shell structure with good thermal stability, good adsorption performance (16.43 mg/g) and fast adsorption performance. The adsorption kinetics of formononetin was consistent with the quasi-second-order kinetics model, and the adsorption process was consistent with the Langmuir monolayer adsorption with good reproducibility. HPLC test results show that MTMIPs can be used to separate and enrich formononetin from complex samples.

    Process system engineering
    Multi-objective operation optimization of olefin separation process for MTO plant
    Lu YANG, Shuoshi LIU, Xiaoyan LUO, Siyu YANG, Yu QIAN
    2020, 71(10):  4720-4732.  doi:10.11949/0438-1157.20200698
    Abstract ( 137 )   HTML ( 8)   PDF (2102KB) ( 92 )  
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    In modern coal processing industries, methanol-to-olefins (MTO) is an important equipment. Its olefin separation process is facing with problems such as the change of raw materials, the loss of olefin products and the high consumption of utilities. Operation optimization is required to achieve maximum benefits under the circumstance of quality assurance and requirements. This article takes the pre-depropanized olefin separation process of Lummus as the research object. And the optimization objectives are the total yield of ethylene and propylene as well as the total energy consumption. Modeling, simulation and multi-objective optimization of the process are conducted. Non-dominated sorting genetic algorithm (NSGA-II) is used to solve multi-objective optimization problem. The simultaneous optimization of 15 operational variables is achieved. Under the current yield, the optimal operation point is found by reducing the reflux ratio of low pressure depropanizer, deethanizer and 1# propylene tower and so on. The results show that the optimal operating point can reduce energy consumption by 20 MW compared with the existing operating point. The optimization interval of each operation variable corresponding to different trade-off points is determined by the comprehensive analysis of decision variables. It is also found that distillation equipment can operate in different optimal operation intervals.

    Surface and interface engineering
    Study on highly efficient corrosion inhibition of copper by regular self-aggregates of organic molecule
    Xue LUO, Chuan JING, Haijun HUANG, Hongru LI, Zhiyong WANG, Zhenqiang WANG, Fang GAO, Shengtao ZHANG
    2020, 71(10):  4733-4749.  doi:10.11949/0438-1157.20191318
    Abstract ( 89 )   HTML ( 1)   PDF (4568KB) ( 41 )  
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    This study presents synthesis of target ionic bistriazole rings-based molecule, 4,4'-{benzene-1,3-diylbis[(1E)-3-oxoprop-1-ene-1,3-diyl]}bis[2-(2H-benzotriazol-2-yl)phenolate] dipotassium (BDBD), through multi-step preparation route. At room temperature, the target molecule can self-assemble to produce nano-micron self-aggregates in a 3.5%(mass) NaCl / DMSO (dimethyl maple) mixed solution (volume ratio, 40/60). It is shown that the predominantly strong chemical adsorption of the formed molecular self-aggregates on the studied copper specimen leads to the yield of self-assembly film on copper surface, which is characterized by FT-IR, Raman and XPS spectroscopy. The corrosion inhibition performance of the stable self-aggregates adsorbed-copper specimens in 3.5%(mass) brine solution based on electrochemical method is surveyed. The results show that the target molecular self-aggregates can effectively inhibit copper corrosion in NaCl solution.

    Preparation and characterization of durable superhydrophobic protective coatings on aluminum alloy
    Lei LIU, Yue ZHANG, Xia LI, Jinglei LEI, Lingjie LI
    2020, 71(10):  4750-4759.  doi:10.11949/0438-1157.20200591
    Abstract ( 116 )   HTML ( 3)   PDF (1791KB) ( 49 )  
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    The durable superhydrophobic protective coatings on the 7B04 aluminum alloy surface was prepared by using acid etching and boiling water bath to construct micro-nano hierarchical structure, and then spraying suspension containing aluminum phosphate adhesive (AP) and perfluorooctyltrichlorosilane (PFOTS) to increase adhesion and reduce surface energy. The samples were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), contact angle measurement (CA), electrochemical impedance spectroscopy(EIS) and a variety of the environmental simulation experiments. The results showed that the static water contact angle (WCA) of the surface is 158.4° and the slide angle (SA) is about 0°, suggesting superhydrophobicity and low adhesion to water. The coating resistance (Rc) was as high as 101.55 kΩ· cm2 and the charge transfer resistance (Rt) in NaCl corrosion medium increased by nearly two orders of magnitude, showing excellent protective performance. The sample can withstand a variety of damages, with ideal mechanical durability, chemical durability and environmental durability.

    High efficient corrosion inhibition of steel by nano-micro aggregates of Sapindus mukorossi Gaertn peel extracts
    Xue LUO, Haijun HUANG, Ziping LUO, Zhiyong WANG, Xiaojing MU, Hongru LI, Xinchao WANG, Shengtao ZHANG, Fang GAO
    2020, 71(10):  4760-4772.  doi:10.11949/0438-1157.20200065
    Abstract ( 83 )   HTML ( 1)   PDF (3375KB) ( 37 )  
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    To seek green, sustainable and natural plant extracts with the potential for large-scale application as corrosion inhibitors, this article selects the extracts of the Sapindus mukorossi Gaertn peels with surfactant properties as the research object. Hence, this article uses Sapindus mukorossi Gaertn peel extracts (SMGPE) with surfactant properties as the study candidate. This survey presents efficient extraction of Sapindus mukorossi Gaertn peels by simply refluxing ethanol solution. It is shown that SMGPE can process orderly nano-micro meters aggregation in DMF/HCl (volume ratio: 50/50, 1.0 mol/L HCl solution) mixed solution through self-organization at the room temperature.The results show that the predominantly strong chemical adsorption of formed SMGPE aggregates on the studied Q235 steel specimens is suggested through the detection of FT-IR, Raman as well as XPS spectroscopy. This study further determines the corrosion inhibition effect of the stable SMGPE aggregates for the studied steel specimens in 1.0 mol/L HCl aqueous solution based on electrochemical method. The results suggest that the SMGPE aggregates can inhibit corrosion of the steel specimens in HCl solution efficiently, and the greatest corrosion inhibition efficiency is over 90%.

    Biochemical engineering and technology
    Treatment of biomass tar by CO2 plasma
    Ming ZHANG, Lehao LI, Rulong LI, Jianhua WU, Baogen SU, Guangdong WEN, Qiwei YANG, Qilong REN
    2020, 71(10):  4773-4782.  doi:10.11949/0438-1157.20200879
    Abstract ( 89 )   HTML ( 3)   PDF (1335KB) ( 66 )  
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    The tar produced in the process of biomass gasification would not only corrode the pipelines and equipment, but also reduce the efficiency of biomass gasification. Traditional methods, such as physical treatment and thermal cracking, have deficiencies which severely restrict their application. This article achieved efficient transformation (carbon yield >90%) from benzene and naphthalene, regarded as model compounds of biomass tar, to syngas using CO2 plasma on self-designed rotating arc plasma torch, proving the feasibility of CO2 plasma treatment of biomass tar. Further analysis on the composition of practical biomass tar and the investigation of biomass tar gasification were carried out. Water content in biomass tar could be used as gasification agent and control the H2/CO scale (0.3—1). The above results provide new ideas for the development of biomass tar harmlessness and resource utilization technology.

    Study on modification of NH2-MCM-41 and its pH-responsive drug release
    Yanqin XU, Zhao QIN, Ye WANG, Yuan CAO, Changguo CHEN, Dan WANG
    2020, 71(10):  4783-4791.  doi:10.11949/0438-1157.20191604
    Abstract ( 86 )   HTML ( 6)   PDF (2251KB) ( 34 )  
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    Mesoporous silica (MCM-41) was synthesized by copolycondensation of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES). Firstly, it was modified with amino group. Then, four different drug carriers, Me-Ph-NH-MCM-41, OHC-Ph-NH-MCM-41, HO-Ph-NH-MCM-41, and HOOC-Ph-NH-MCM-41, were synthesized by grafting —R group (—R: —CHO, —OH, —CH3, —COOH), respectively. FT-IR, SEM, Zeta potential, and XRD were used to characterize its structure and morphology, indicating the successful synthesis of modified MCM-41. Rhodamine B (RhB) was used as a model for drug loading performance testing and the sensitive drug release behavior of this drug release system under different pH simulated humors was investigated. The effects of different —R groups on drug release were also explored. The results show that the four carriers hardly release drugs under neutral conditions. The drug release can be effectively controlled by changing the pH of the environmental system. The drug release behavior can be described by the Korsmeyer-Peppas kinetic model. The experiment showed that the drug release amount: RhB@HOOC-Ph-NH-MCM-41>RhB@OHC-Ph-NH-MCM-41>RhB@HO-Ph-NH-MCM-41>RhB@Me-Ph-NH-MCM-41. The pH-response of drug carriers with different —R groups was different, and the drug release amount of RhB@HOOC-Ph-NH-MCM-41 reached 57.87% at pH = 1.2, which has some potential applications in intelligent controlled release materials of drugs.

    Energy and environmental engineering
    Research on leaching rate enhancement and organic matter removal in wet-process phosphoric acid
    Changyuan TAO, Xiuxiu WANG, Zuohua LIU, Renlong LIU, Jinhua LUAN
    2020, 71(10):  4792-4799.  doi:10.11949/0438-1157.20200672
    Abstract ( 90 )   HTML ( 1)   PDF (1293KB) ( 34 )  
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    In the process of wet-process phosphoric acid leaching, the product phosphoric acid appears black due to the incomplete carbonization of some organic matter. A novel type of catalytic oxidation wet-process phosphoric acid purification technology was proposed in this work. During the leaching process, the oxidant (H2O2) and catalyst (MnO2) was added to form the peroxides such as ·OH and HO2· in the transformation process, which can enhance the removal rate of organic matter and strengthen the leaching rate of phosphate rock. The different reaction conditions that affected the leaching rate of wet-phosphoric acid and the removal of organic matter were investigated. The results indicated that 96.9% of phosphate rock were leached under the optimum conditions of H2O2 dosage 0.08 ml/g, MnO2/P mass ratio of 0.04, 80℃ and for 40 min. At the same time, the TOC remove rate reached 79%. The analysis mechanism showed that H2O2 will form H3PO4 · H2O2 peroxide with H3PO4 in the solution, and MnO2 will react with it like Fenton to generate a large amount of ·OH, and then fully oxidized the black organic matter into CO2 and H2O. Organic matter “wrapped” on the surface of the phosphate rock is broken by ·OH, which promoted the leaching of phosphoric acid and enhanced the removal of organic matter.

    Material science and engineering, nanotechnology
    Synthesis of ruthenium-embedded nitrogen-doped graphene for carbon dioxide hydrogenation
    Lu LI, Linghui LIU, Jinming XU, Yanqiang HUANG, Tao ZHANG
    2020, 71(10):  4800-4807.  doi:10.11949/0438-1157.20200680
    Abstract ( 80 )   HTML ( 5)   PDF (4605KB) ( 37 )  
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    Two-dimensional (2D) layered materials have attracted great interest in the energy storage and catalysis field due to their graphene-like structure and excellent performance. Ruthenium-embedded nitrogen-doped graphene (Ru-NG) have been obtained by a novel method, using montmorillonite as hard template and Ru-phenanthroline chelate as precursor. After calcination in N2 atmosphere at 800℃, Ru-NG were obtained and further characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and nitrogen sorption. Ru-NG have 2D layered structure just like the montmorillonite template, and C, N, O and Ru are homogeneously distributed on them. The average sizes of Ru nanoparticles do not change much with the increasing of Ru content, and they keep at about 1.2 to 1.4 nm. The XPS results indicate that phenanthroline has been successfully transformed to nitrogen-doped carbon during pyrolysis, and the peaks at 398.5, 400.1 and 401.5 eV suggest the presence of pyridine-like, pyrrole-like and quaternary nitrogen atoms, respectively. Compared with the Ru catalyst supported on activated carbon prepared by the traditional impregnation-reduction method, Ru-NG exhibits excellent catalytic activity in the reaction of hydrogenation of carbon dioxide to formic acid.

    Synthesis of PEGylation hydroxyapatite drug delivery system and its dual channels fluorescence imaging
    Xiaojing LI, Wen SUN, Yao KANG, Jiangli FAN, Xiaojun PENG
    2020, 71(10):  4808-4819.  doi:10.11949/0438-1157.20200780
    Abstract ( 56 )   HTML ( 2)   PDF (4526KB) ( 21 )  
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    PEGylated drug delivery systems (DDSs) can overcome the side effects of traditional chemotherapy by enhancing drug permeability and retention (EPR) effects. In this work, DOX@HAP (hydroxyapatite) was initially fabricated via the coprecipitation and hydrothermal method, further functionalized with Cy (cyanine) by coupling reaction of APTES and then introduced hydrophilic PEG chains by using copper(I)-catalyzed alkyne–azide cycloaddition reaction. Physicochemical properties including the morphology, particle size and phase composition, were characterized by TEM, SEM, particle size analyzer, FTIR, XPS and XRD. The encapsulation efficiency and drug release profile of DOX@HAP-Cy-PEG were analyzed by UV-Vis spectrophotometry. Furthermore, the cellular uptake of DOX@HAP-Cy-PEG nanoparticles in Hela and HepG2 cells was monitored by the dual channels fluorescence imaging of DOX and Cy. The results showed that DOX@HAP-Cy-PEG nanoparticles could be used to real-time monitor the dynamic distribution of DDSs in Hela and HepG2 cells by dual channels.

    Theoretical study on electrocatalytic nitrogen fixation performance of two-dimensional AuP2
    Xiaorong ZHU, Yafei LI
    2020, 71(10):  4820-4825.  doi:10.11949/0438-1157.20200714
    Abstract ( 56 )   HTML ( 2)   PDF (1484KB) ( 30 )  
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    The electrochemical conversion of nitrogen (N2) and water (H2O) into ammonia (NH3) under normal temperature and pressure conditions is a green and environmentally friendly method of ammonia synthesis. However, because N2 has a very high chemical inertness, an electrocatalyst must be used to accelerate the kinetic process of the reaction. In this paper, we use density functional theory calculations to reveal that AuP2, a new type of two-dimensional inorganic material, has good catalytic activity for the electrochemical reduction of N2 to NH3. In the two-dimensional AuP2 material, significant charge transfer occurs between Au and P atoms due to the difference in electronegativity, so that positively charged P can be used as an active site to promote nitrogen reduction. Our calculations show that the rate-determining step of the entire reaction is the process of generating *NNH from N2 with a limiting voltage of 1.2 V, and the catalytic activity can be comparable to some metal catalysts. This work provides new ideas for the design of high-efficiency nitrogen reduction electrocatalysts.

    Study on thermal properties of stearyl alcohol modified graphene oxide/ n-octadecane composite phase change materials
    Di CAI, Jing LI
    2020, 71(10):  4826-4835.  doi:10.11949/0438-1157.20191231
    Abstract ( 74 )   HTML ( 2)   PDF (3728KB) ( 42 )  
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    Adding high thermal conductivity fillers to n-octadecane to form a composite phase change material(PCM) can improve its thermal conductivity. At the same time, to ensure high thermal conductivity, dispersion stability and recycling reliability of PCM, a type of composite PCM has been fabricated by grafting stearic alcohol onto graphene oxide (GO). The modified graphene/n-octadecane composite PCMs with 0, 1%, 2%, 3% and 4%(mass) of modified graphene were prepared to characterize and study of feature structure and thermophysical properties by means of scanning electron microscope, infrared spectrum analysis, differential scanning calorimetry and thermal conductivity analysis, etc. Experiments show that the modified graphene/n-octadecane composite PCMs prepared in this paper has good dispersion stability. When the mass fraction of modified graphene reaches 4%, the thermal conductivity of composite PCMs is 131.9% higher than that of pure n-octadecane.

    Construction of free binder V2O5 and Fe2O3 flexible electrode and its application in supercapacitor
    Bingbing HU, Shu YANG, Yan LI, Chuanlan XU, Peng CHEN, Jingjing YU, Danmei YU, Changguo CHEN
    2020, 71(10):  4836-4846.  doi:10.11949/0438-1157.20191307
    Abstract ( 83 )   HTML ( 3)   PDF (3152KB) ( 33 )  
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    In recent years, more and more research has been devoted to the development of new electrode materials with ultra-high energy density and high Faraday reaction activity, especially applying them to a new generation of supercapacitor energy storage systems. In this study, sea urchin-shaped V2O5 nanospheres and tetrakaidecahedron Fe2O3 nano boxes have been grown directly on flexible matrix carbon cloth by hydrothermal method. The hydrothermal time can control the microstructure of V2O5, and the morphology determines the performance of energy storage, the positive electrode material of sea urchin-shaped V2O5 nanosphere exhibits a maximum specific capacitance of 535 F·g-1. In addition, the tetrakaidecahedron Fe2O3 nano box is used as the negative electrode, and a new structure V2O5//Fe2O3 flexible supercapacitor is assembled. When the power density is 699.49 W·kg-1, the energy density can reach 46.06 W·h·kg-1. Moreover, it also has good mechanical flexibility, and the specific capacity retention rate is still as high as 83.4% after 5000 times of 180° bending cycle tests. This work provides a general and effective strategy for developing the next generation flexible electronic devices with ultra-high energy density.