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Table of Content
28 June 2021, Volume 34 Issue 6
    Fluid Dynamics and Transport Phenomena
    Spray and mixing characteristics of liquid jet in a tubular gas-liquid atomization mixer
    Lingzhen Kong, Jiaqing Chen, Tian Lan, Huan Sun, Kuisheng Wang
    2021, 34(6):  1-11.  doi:10.1016/j.cjche.2020.08.016
    Abstract ( 185 )   PDF (1293KB) ( 116 )  
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    For the design and optimization of a tubular gas-liquid atomization mixer, the atomization and mixing characteristics of liquid jet breakup in the limited tube space is a key problem. In this study, the primary breakup process of liquid jet column was analyzed by high-speed camera, then the droplet size and velocity distribution of atomized droplets were measured by Phase-Doppler anemometry (PDA). The hydrodynamic characteristics of gas flow in tubular gas-liquid atomization mixer were analyzed by computational fluid dynamics (CFD) numerical simulation. The results indicate that the liquid flow rate has little effect on the atomization droplet size and atomization pressure drop, and the gas flow rate is the main influence parameter. Under all experimental gas flow conditions, the liquid jet column undergoes a primary breakup process, forming larger liquid blocks and droplets. When the gas flow rate (Qg) is less than 127 m3·h-1, the secondary breakup of large liquid blocks and droplets does not occur in venturi throat region. The Sauter mean diameter (SMD) of droplets measured at the outlet is more than 140 μm, and the distribution is uneven. When Qg > 127 m3·h-1, the large liquid blocks and droplets have secondary breakup process at the throat region. The SMD of droplets measured at the outlet is less than 140 μm, and the distribution is uniform. When 127 < Qg < 162 m3·h-1, the secondary breakup mode of droplets is bag breakup or pouch breakup. When 181 < Qg < 216 m3·h-1, the secondary breakup mode of droplets is shear breakup or catastrophic breakup. In order to ensure efficient atomization and mixing, the throat gas velocity of the tubular atomization mixer should be designed to be about 51 m·s-1 under the lowest operating flow rate. The pressure drop of the tubular atomization mixer increases linearly with the square of gas velocity, and the resistance coefficient is about 2.55 in single-phase flow condition and 2.73 in gas-liquid atomization condition.
    Dynamics of self-organizing single-line particle trains in the channel flow of a power-law fluid
    Xiao Hu, Jianzhong Lin, Dongmei Chen, Xiaoke Ku
    2021, 34(6):  12-21.  doi:10.1016/j.cjche.2020.10.009
    Abstract ( 163 )   PDF (1392KB) ( 111 )  
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    The formation of self-organizing single-line particle train in a channel flow of a power-law fluid is studied using the lattice Boltzmann method with power-law index 0.6≤n≤1.2, particle volume concentration 0.8%≤Φ≤6.4%, Reynolds number 10≤Re≤100, and blockage ratio 0.2≤k≤0.4. The numerical method is validated by comparing the present results with the previous ones. The effect n, Φ, Re and k on the interparticle spacing and parallelism of particle train is discussed. The results showed that the randomly distributed particles would migrate towards the vicinity of the equilibrium position and form the ordered particle train in the power-law fluid. The equilibrium position of particles is closer to the channel centerline in the shear-thickening fluid than that in the Newtonian fluid and shear-thinning fluid. The particles are not perfectly parallel in the equilibrium position, hence IH is used to describe the inclination of the line linking the equilibrium position of each particle. When self-organizing single-line particle train is formed, the particle train has a better parallelism and hence benefit for particle focusing in the shear-thickening fluid at high Φ, low Re and small k. Meanwhile, the interparticle spacing is the largest and hence benefit for particle separation in the shear-thinning fluid at low Φ, low Re and small k.
    Numerical simulation and experimental study of the characteristics of packing feature size on liquid flow in a rotating packed bed
    Xifan Duan, Zhiguo Yuan, Youzhi Liu, Hangtian Li, Weizhou Jiao
    2021, 34(6):  22-31.  doi:10.1016/j.cjche.2020.09.063
    Abstract ( 133 )   PDF (920KB) ( 59 )  
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    Rotating packed bed has high efficiency of gas–liquid mass transfer. So it is significant to investigate fluid motion in rotating packed bed. Numerical simulations of the effects of packing feature size on liquid flow characteristics in a rotating packed bed are reported in this paper. The particle image velocimetry is compared with the numerical simulations to validate the turbulent model. Results show that the liquid exists in the packing zone in the form of droplet and liquid line, and the cavity is droplet. When the radial thickness of the packing is less than 0.101 m, liquid line and droplets appear in the cavity. When rotational speed and radial thickness of the packing increase, the average diameter of the droplets becomes smaller, and the droplet size distribution becomes uniform. As the initial velocity of the liquid increases, the average droplet diameter increases and the uniformity of particle size distribution become worse. The droplet velocity increases with the radial thickness of the packing increasing, and gradually decreases when it reaches the cavity region. The effect of packing thickness is most substantial through linear fitting. The predicted and simulated values are within ±15%. The cumulative volume distribution curves of the experimental and simulated droplets are consistent with the R-R distribution.
    Transformation of single drop breakup from binary to ternary and multiple in turbulent jet flows
    Wenjun Liang, Dengfei Wang, Meijuan Qian, Ziqi Cai, Zhipeng Li, Zhengming Gao
    2021, 34(6):  32-39.  doi:10.1016/j.cjche.2020.11.039
    Abstract ( 99 )   PDF (806KB) ( 89 )  
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    By releasing liquid drops in turbulent jet flows, we investigated the transformation of single drop breakup from binary to ternary and multiple. Silicone oil and deionized water were the dispersed phase and continuous phase, respectively. The probability of binary, ternary, and multiple breakup of oil drops in jet flows is a function of the jet Reynolds number. To address the underlying mechanisms of this transformation of drop breakup, we performed two-dimensional particle image velocimetry (PIV) experiments of single-phase jet flows. With the combination of drop breakup phenomenon and two-dimensional PIV results in a single-phase flow field, these transformation conditions can be estimated: the capillary number ranges from 0.17 to 0.27, and the Weber number ranges from 55 to 111.
    Radiation-absorption, chemical reaction, Hall and ion slip impacts on magnetohydrodynamic free convective flow over semi-infinite moving absorbent surface
    M. Veera Krishna
    2021, 34(6):  40-52.  doi:10.1016/j.cjche.2020.12.026
    Abstract ( 107 )   PDF (810KB) ( 229 )  
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    The investigation of radiation-absorption, chemical reaction, Hall and ion-slip impacts on unsteady MHD free convective laminar flow of an incompressible viscous, electrically conducting and heat generation/ absorbing fluid enclosed with a semi-infinite porous plate within a rotating frame has been premeditated. The plate is assumed to be moving with a constant velocity in the direction of fluid movement. A uniform transverse magnetic field is applied at right angles to the porous surface, which is absorbing the fluid with a suction velocity changing with time. The non-dimensional governing equations for present investigation are solved analytically making use of two term harmonic and non-harmonic functions. The graphical results of velocity, temperature and concentration distributions on the analytical solutions are displayed and discussed with reference to pertinent parameters. It is found that the velocity profiles decreased with an increasing in Hartmann number, rotation parameter, the Schmidt number, heat source parameter, while it increased due to an increase in permeability parameter, radiation-absorption parameter, Hall and ion slip parameters. However, the temperature profile is an increasing function of radiation- absorption parameter, whereas an increase in chemical reaction parameter, the Schmidt number Sc or frequency of oscillations decrease the temperature profile on cooling. Also, it is found that the concentration profile is decreased with an escalating in the Schmidt number or the chemical reaction parameter.
    Separation Science and Engineering
    Characterization of oil component and solid particle of oily sludge treated by surfactant-assisted ultrasonication
    Zuhong Lin, Fushuai Xu, Lili Wang, Liyang Hu, Lingfu Zhu, Jie Tan, Zhifeng Li, Tingting Zhang
    2021, 34(6):  53-60.  doi:10.1016/j.cjche.2020.08.001
    Abstract ( 95 )   PDF (866KB) ( 43 )  
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    The ultrasonic technique has been demonstrated to be a promising method for the disposal of hazardous oily sludge. However, the separation of oil from the surfaces of the solid particles is still difficult due to the strong interaction between the oil and solid particle. In this study, three types of surfactants were used to assist the ultrasonic treatment of oily sludge. The oil component, surface composition, and structure of the solid particle were determined. The results showed that different surfactants had different oil removal abilities. In the three surfactant-assisted sonication systems, the oil removal rate increased during the starting reaction period and then decreased with longer sonication time. The results of four components analysis suggested that surfactant easy to be ionized in water posed a better removal effect on resins, while the amphiphilic surfactant preferred saturates, aromatics and asphaltenes. The morphology analysis indicated that particle size was shattered into smaller ones by the ultrasonic process, and the wettability of the solid surface also changed during this treatment. The characterization of the oil component and solid particle during surfactant-assisted ultrasonication treatment will help to better understand the separation of oil from oily sludge and improve the oil recovery efficiency from oily sludge.
    Experimental determination of gas holdup and volumetric mass transfer coefficient in a jet bubbling reactor
    Mostafa Abbasian-arani, Mohammad Sadegh Hatamipour, Amir Rahimi
    2021, 34(6):  61-67.  doi:10.1016/j.cjche.2020.07.051
    Abstract ( 93 )   PDF (814KB) ( 71 )  
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    The hydrodynamics and mass transfer characteristics of a lab-scale jet bubbling reactor (JBR) including the gas holdup, volumetric mass transfer coefficient and specific interfacial area were assessed experimentally investigating the influence of temperature, pH and superficial gas velocity. The reactor diameter and height were 11 and 30 cm, respectively. It was equipped with a single sparger, operating at atmospheric pressure, 20 and 40℃, and two pH values of 3 and 6. The height of the liquid was 23 cm, while the superficial gas velocity changed within 0.010-0.040 m·s-1 range. Experiments were conducted with pure oxygen as the gas phase and saturated lime solution as the liquid phase. The liquid-side volumetric mass transfer coefficient was determined under unsteady-state oxygen absorption in a saturated lime solution. The gas holdup was calculated based on the liquid height change, while the specific interfacial area was obtained by a physical method based on the bubble size distribution (BSD) in different superficial gas velocities. The results indicated that at the same temperature but different pH, the gas holdup variation was negligible, while the liquid-side volumetric mass transfer coefficient at the pH value of 6 was higher than that at the pH=3. At a constant pH but different temperatures, the gas holdup and the liquid-side volumetric mass transfer coefficients at 40℃ were higher than that of the same at 20℃. A reasonable and appropriate estimation of the liquid-side volumetric mass transfer coefficient (kla) in a pilot-scale JBR was provided which can be applied to the design and scale-up of JBRs.
    Preparation and adsorption performance of multi-morphology H1.6Mn1.6O4 for lithium extraction
    Xiulei Li, Baifu Tao, Qingyuan Jia, Ruili Guo
    2021, 34(6):  68-76.  doi:10.1016/j.cjche.2020.09.006
    Abstract ( 98 )   PDF (926KB) ( 181 )  
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    In this paper, a lithium-ion sieve (LIS) with different morphologies, such as rod-like (LIS-R), spherical (LIS-S), flower-like (LIS-F), and three-dimensional macroporous-mesoporous (LIS-3D), was prepared by hydrothermal synthesis, solid reaction, and hard-template synthesis. The results showed that the LIS with different morphologies presented great differences in specific surface area, pore volume, adsorption selectivity, and structure stability. LIS-3D with highest specific surface area and pore volume displayed the maximum adsorption capacity and adsorption rate, but the stability of LIS-3D was poor because of the manganese dissolution. By comparison, LIS-S has the best structural stability while maintaining a satisfactory adsorption capacity (35.02 mg·g-1) and adsorption rate. The LIS-S remained about 90% of the original adsorption capacity after five cycles of adsorption-desorption process. In addition, in the simulated brine system (the magnesium to lithium ratio of 400), the LIS-S exhibited the highest selectivity (αMgLi) of 425.14. In sum, the LIS-S with good morphology is a potential adsorbent for lithium extraction from brine.
    Catalysis, Kinetics and Reaction Engineering
    Oxidative dehydrogenation of ethane with carbon dioxide over silica molecular sieves supported chromium oxides: Pore size effect
    Zhibin Deng, Xing Ge, Wenting Zhang, Shizhong Luo, Jun Shen, Fangli Jing, Wei Chu
    2021, 34(6):  77-86.  doi:10.1016/j.cjche.2020.08.006
    Abstract ( 85 )   PDF (1008KB) ( 58 )  
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    SBA-15 with varied pore size from 4 to 8 nm were synthesized by tuning the temperature of hydrothermal treatment, the supports were then used to load the active phase CrOx through a conventional impregnation method. The resulting catalysts were characterized by small/wide angle XRD, N2 adsorption/desorption, FT-IR, TEM-EDX, XPS, TPR and CO2-TPD to study the feature of structure, surface chemical state, redox and basicity. It was found from these results that the metal species could be well dispersed on catalysts with larger pore size. Cr6+ species could enter into the framework by substituting the Si atoms of SBA-15, and Cr3+ mainly exist on extra framework. Pore size had profound effects on reducibility, surface composition and basicity. Cr6+ species were necessary to activate the C-H bonds of alkanes, while the basicity played an important role in activating C-O bonds of CO2. The best performances were achieved over the sample Cr supported on SBA-15 with a pore diameter of 7 nm in oxidative dehydrogenation of ethane in the presence of CO2.
    Pore-level numerical simulation of methane-air combustion in a simplified two-layer porous burner
    Yang Liu, Yangbo Deng, Junrui Shi, Rujie Xiao, Houping Li
    2021, 34(6):  87-96.  doi:10.1016/j.cjche.2020.09.061
    Abstract ( 76 )   PDF (856KB) ( 77 )  
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    A simplified two-dimensional model of two-layer porous burner based on pore level is developed. The heat transfer of solid phase in porous burner is seen as the synergistic effects of conduction through connecting bridges and surface radiation between the solid particles in the model. A numerical simulation study on the characteristics of flow, combustion and heat transfer in the two-layer porous burner is carried out using the pore level model, and the effects of the control parameters such as the inlet velocity and solid thermal conductivity on thermal non-equilibrium are investigated. The results show that the flame structure is highly two-dimensional based on pore level. Obvious thermal non-equilibrium in the burner for the two phases and solid phase are observed, the largest temperature difference between the gas and solid phases is observed in combustion zone, while the temperature difference inside the solid particles is largest near the flame front. The results also reveal that thermal non-equilibrium of porous burner is much affected by the inlet velocity and solid thermal conductivity.
    Simulation of the hydrodynamics and mass transfer in a falling film wavy microchannel
    Siyuan Chen, Tao Zhang, Li Lv, Yanxiao Chen, Shengwei Tang
    2021, 34(6):  97-105.  doi:10.1016/j.cjche.2020.09.014
    Abstract ( 117 )   PDF (739KB) ( 155 )  
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    The flow in a liquid falling film is predominantly laminar, and the liquid-side mass transfer is limited by molecular diffusion. The effective way to enhance the mass transfer is to improve the liquid film flow behavior. The falling film behaviors of water, ethanol and ethylene glycol in nine different wavy microchannels were simulated by Computational Fluid Dynamics. The simulation results show that the falling film thickness exhibits a waveform distribution resulting in a resonance phenomenon along the wavy microchannel. The fluctuation of liquid film surface increases the gas–liquid interface area, and the internal eddy flow inside the liquid film also improves the turbulence of liquid film, the gas–liquid mass transfer in falling film microchannels is intensified. Compared with flat microchannel, the CO2 absorption efficiency in water in the wavy microchannel is improved over 41%. Prediction models of liquid film amplitude and average liquid film thickness were established respectively.
    Process Systems Engineering and Process Safety
    Data-driven optimal operation of the industrial methanol to olefin process based on relevance vector machine
    Zhiquan Wang, Liang Wang, Zhihong Yuan, Bingzhen Chen
    2021, 34(6):  106-115.  doi:10.1016/j.cjche.2020.09.040
    Abstract ( 104 )   PDF (660KB) ( 148 )  
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    Methanol to olefin (MTO) technology provides the opportunity to produce olefins from nonpetroleum sources such as coal, biomass and natural gas. More than 20 commercial MTO plants have been put into operation. Till now, contributions on optimal operation of industrial MTO plants from a process systems engineering perspective are rare. Based on relevance vector machine (RVM), a data-driven framework for optimal operation of the industrial MTO process is established to fully utilize the plentiful industrial data sets. RVM correlates the yield distribution prediction of main products and the operation conditions. These correlations then serve as the constraints for the multi-objective optimization model to pursue the optimal operation of the plant. Nondominated sorting genetic algorithm II is used to solve the optimization problem. Comprehensive tests demonstrate that the ethylene yield is effectively improved based on the proposed framework. Since RVM does provide the distribution prediction instead of point estimation, the established model is expected to provide guidance for actual production operations under uncertainty.
    Local component based principal component analysis model for multimode process monitoring
    Yuan Li, Dongsheng Yang
    2021, 34(6):  116-124.  doi:10.1016/j.cjche.2020.10.030
    Abstract ( 119 )   PDF (1401KB) ( 96 )  
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    For plant-wide processes with multiple operating conditions, the multimode feature imposes some chal lenges to conventional monitoring techniques. Hence, to solve this problem, this paper provides a novel local component based principal component analysis (LCPCA) approach for monitoring the status of a multimode process. In LCPCA, the process prior knowledge of mode division is not required and it purely based on the process data. Firstly, LCPCA divides the processes data into multiple local components using finite Gaussian mixture model mixture (FGMM). Then, calculating the posterior probability is applied to determine each sample belonging to which local component. After that, the local component information (such as mean and standard deviation) is used to standardize each sample of local component. Finally, the standardized samples of each local component are combined to train PCA monitoring model. Based on the PCA monitoring model, two monitoring statistics T2 and SPE are used for monitoring multimode pro cesses. Through a numerical example and the Tennessee Eastman (TE) process, the monitoring result demonstrates that LCPCA outperformed conventional PCA and LNS-PCA in the fault detection rate.
    Chemical Engineering Thermodynamics
    Innovative surfactant of Gemini-type for dissolution mitigation of steel in pickling HCl medium
    Medhat Kamel, Mohamed Hegazy, Salah Rashwan, Mohamed El Kotb
    2021, 34(6):  125-133.  doi:10.1016/j.cjche.2020.09.051
    Abstract ( 115 )   PDF (999KB) ( 76 )  
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    A new surfactant of Gemini-type, N,N'-((phthylbis(oxy))bis(ethane-2,1-diyl))bis(N,N-dimethyldodecan- 1-aminium bromide) is prepped & confirmed. The dissolution suppression impact of the new compound on steel is performed in 1 mol·L-1 HCl environment by means of chemical and electrochemical methods. The prepared surfactant is an agreeable dissolution inhibitor for steel. The mitigation efficacy rises with the quantity of the compound. The surfactant belongs to inhibitors of mixed-type. The adsorption of the synthesized compound followed the Langmuir's model. The negative magnitudes of both ΔGadsθ and ΔHadsθ indicate that the adsorption process proceeds from its own accord and exothermic. The mechanism of adsorption is elucidated by scanning microscopy. It is established that the transfer resistance (Rct) value rose, where the value of the phase element (CPE) reduced with the amount of synthesized inhibitor. According to the experimental data arrived by surface tension measurements, the prepared compound is a powerful active agent at the air/water boundary.
    Thermodynamic modeling and phase diagram prediction of salt lake brine systems II. Aqueous Li+-Na+-K+-SO42- and its subsystems
    Huan Zhou, Peng Wu, Wenxuan Li, Xingfan Wang, Kuo Zhou, Qing Hao
    2021, 34(6):  134-149.  doi:10.1016/j.cjche.2020.11.040
    Abstract ( 146 )   PDF (2146KB) ( 302 )  
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    It is still a challenging task to accurately and temperature-continuously express the thermodynamic properties and phase equilibrium behaviors of the salt-lake brine with multi-component, multi-temperature and high concentration. The essential subsystem of sulfate type brine, aqueous Li+-Na+-K+-SO42- and its subsystems across a temperature range from 250 K to 643 K are investigated with the improved comprehensive thermodynamic model. Liquid parameters (ΔgIJ, ΔhIJ, and ΔCp,IJ) associated with the contributions of Gibbs energy, enthalpy, and heat capacity to the binary interaction parameters, i.e. the temperature coefficients of eNRTL parameters formulated with a Gibbs Helmholtz expression, are determined via multi-objective optimization method. The solid constants ΔfGk°(298.15) and ΔfHk°(298.15) of 11 solid species occurred in the quaternary system are rebuilt from multi-temperature solubilities. The modeling results show the accurate representation of (1) solution properties and binary phase diagram at temperature ranges from eutectic points to 643 K; (2) isothermal phase diagrams for Li2SO4-Na2SO4-H2O, Li2SO4-K2SO4-H2O and Na2SO4-K2SO4-H2O ternary systems. The predicted results of complete structure and polythermal phase diagram of ternary systems and the isothermal phase diagrams of quaternary system excellently match with the experimental data.
    Numerical simulation of two-phase flow and droplet breakage of glycerin-water mixture and kerosene in the cyclone reactor
    Yanni Chi, Rui Zhang, Xianghai Meng, Jian Xu, Wei Du, Haiyan Liu, Zhichang Liu
    2021, 34(6):  150-159.  doi:10.1016/j.cjche.2021.02.021
    Abstract ( 105 )   PDF (838KB) ( 139 )  
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    A liquid-liquid cyclone reactor (LLCR) was designed to achieve mixing-reaction-separation integration during isobutane alkylation catalyzed by ionic liquids. However, studies of the droplets deformation and breakage in the kind of reactors are lacking. In this work, the research studied the velocity distribution, pressure field, and turbulent field to investigate the flow pattern and the main energy loss location in the LLCR through the computational fluid dynamics (CFD) method. The simulation results were verified by experiemnts to prove the correctness of the model. Then the deformation and breakage process of droplets, and the influencing factors of droplets breakage were studied by remodeling which was based on the tangential velocity distribution result of the three dimensional model. The three dimensional simulation results clearly showed that the pressure of the LLCR was mainly concentrated in the cone section and fluid turbulent motion was the most intense near the lateral wall. The reconstruct the results of the two dimensional model clearly showed that the deformation and breakage location of droplets were mainly occurred in the velocity boundary layer, while it was difficult to break in the mainstream region. In addition, low surface tension and high Weber number had a positive effect on droplet breakage.
    An experimental approach for measuring carbon dioxide diffusion coefficient in water and oil under supercritical conditions
    Mohammad Sadegh Sharafi, Mehdi Ghasemi, Mohammad Ahmadi, Alireza Kazemi
    2021, 34(6):  160-170.  doi:10.1016/j.cjche.2020.08.034
    Abstract ( 91 )   PDF (1783KB) ( 99 )  
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    Several direct or indirect approaches have been proposed to measure diffusion coefficient of gases into liquids. The main complexity of indirect techniques such as pressure decay method is interpreting early pressure–time data which strongly affected by incubation period effect or convective instability. In the current approach, accurate apparatus and precise experimental setup including a high pressure and temperature PVT cell, a high precision Sanchez pump, heating and recording sub-system are implemented and a novel data analysis procedure is applied to modify pressure decay method. The effect of incubation period is reduced remarkably and diffusion coefficient of carbon dioxide in water in wide range of pressures and temperatures is determined and the effects of temperature, pressure and carbon dioxide phase alteration from gas to supercritical are investigated and the value of uncertainty is estimated. Furthermore, diffusion coefficient of CO2 and methane in an oil sample from one of the Iranian southwest oil formations is determined precisely using the experimental approach while no incubation period is detected. The results showed that incubation period duration decreases with increasing diffusion coefficient. Additionally, when CO2 state is gas, rate of increasing diffusion coefficient with pressure is decreased with temperature and when CO2 state is supercritical, the rate of increasing diffusion coefficient with pressure is decreased significantly.
    Catalytic cascade acetylation-alkylation of biofuran to C17 diesel precursor enabled by a budget acid-switchable catalyst
    Chuanhui Li, Yuanzhong Li, Xiaoxiang Luo, Zhengyi Li, Heng Zhang, Hu Li, Song Yang
    2021, 34(6):  171-179.  doi:10.1016/j.cjche.2020.09.037
    Abstract ( 98 )   PDF (892KB) ( 77 )  
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    Lignocellulosic biomass is a promising feedstock for the synthesis of value-added chemicals and biofuels. However, one of the biggest challenges for producing high-quality diesel fuels is the lack of sufficient carbon-chain length in biomass derivatives. In this study, a C17 diesel precursor 1,1,1-tris(5-methyl-2-f uryl)ethane (TEMF) with a yield of ca. 70% was synthesized from the cascade acetylation-hydroxyalkyla tion/alkylation of bio-based 2-methylfuran (MF) with acetic anhydride (AA) catalyzed by acid-treated montmorillonite with enhanced acidity and improved porosity. The catalytic mechanism of the cascade reaction process was investigated over different types of acid species (Brønsted acid and Lewis acid), and the influence of in situ formed acetic acid was also examined. A synergistic effect was observed to enable the synthesis of TEMF from the trimerization of MF with AA, in which Lewis acid and weak Brønsted acid species mainly catalyze the acetylation and hydroxyalkylation processes, while the subsequent alkylation step is mainly catalyzed by strong Brønsted acid.
    Dual-radiation-chamber coordinated overall energy efficiency scheduling solution for ethylene cracking process regarding multi-parameter setting and multi-flow allocation
    Di Meng, Cheng Shao, Li Zhu
    2021, 34(6):  180-197.  doi:10.1016/j.cjche.2020.09.060
    Abstract ( 73 )   PDF (1486KB) ( 225 )  
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    Ethylene cracking process is the core production process in ethylene industry, and is paid more attention to reduce high energy consumption. Because of the interdependent relationships between multi-flow allocation and multi-parameter setting in cracking process, it is difficult to find the overall energy efficiency scheduling for the purpose of saving energy. The traditional scheduling solutions with optimal economic benefit are not applicable for energy efficiency scheduling issue due to the neglecting of recycle and lost energy, as well as critical operation parameters as coil outlet pressure (COP) and dilution ratio. In addition, the scheduling solutions mostly regard each cracking furnace as an elementary unit, regardless of the coordinated operation of internal dual radiation chambers (DRC). Therefore, to improve energy utilization and production operation, a novel energy efficiency scheduling solution for ethylene cracking process is proposed in this paper. Specifically, steam heat recycle and exhaust heat loss are considered in cracking process based on 6 types of extreme learning machine (ELM) based cracking models incorporating DRC operation and three operation parameters as coil outlet temperature (COT), COP, and dilution ratio according to semi-mechanism analysis. Then to provide long-term decision-making basis for energy efficiency scheduling, overall energy efficiency indexes, including overall output per unit net energy input (OONE), output-input ratio per unit net energy input (ORNE), exhaust gas heat loss ratio (EGHL), are designed based on input–output analysis in terms of material and energy flows. Finally, a multi-objective evolutionary algorithm based on decomposition (MOEA/D) is employed to solve the formulated multi-objective mixed-integer nonlinear programming (MOMINLP) model. The validities of the proposed scheduling solution are illustrated through a case study. The scheduling results demonstrate that an optimal balance between multi-flow allocation, multi-parameter setting, and DRC coordinated operation is reached, which achieves 3.37% and 2.63% decreases in net energy input for same product output and conversion ratio, as well as the 1.56% decrease in energy loss ratio.
    Densities and excess molar volumes of mixtures containing diesel, biodiesel and alkanols at temperatures from 288.15 to 313.15 K
    Sunita Malik, Poonam Jangra Darolia, S. K. Garg, V. K. Sharma
    2021, 34(6):  198-207.  doi:10.1016/j.cjche.2020.09.065
    Abstract ( 122 )   PDF (814KB) ( 44 )  
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    The present work is focusing on the synthesization and physico-chemical properties of Jatropha curcas biodiesel with diesel and alcohols. The densities of binary diesel (2) + 1-alkanols (C3 or C4) (3) and ternary Jatropha curcas biodiesel (1) + diesel (2) + 1-alkanols (C3 or C4) (3) blends have been reported over full range of composition at temperatures within range 288.15 to 313.15 K. Also densities of Jatropha curcas biodiesel (1) + diesel or 1-alkanols (C3 or C4) (2) blends have been measured at 313.15 K. Excess molar volumes, VE, V123E of binary and ternary blends were calculated from the measured data and the derived properties were correlated to composition using Redlich–Kister equation. A reasonable agreement was found between the measured and estimated values. Further, densities and excess molar volumes data were reasoned to discuss molecular interactions taking into consideration effect of composition and temperature.
    A design of Nafion-coated bilayered quasi-solid electrolyte for lithium-O2 batteries with high performance
    Yingfei Hou, Lin Jiang, Yaoyao Zhang, Zhiwen Qin, Chi Jiang, Ming Wang
    2021, 34(6):  208-216.  doi:10.1016/j.cjche.2020.10.024
    Abstract ( 91 )   PDF (897KB) ( 99 )  
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    Lithium-air (also known as lithium-oxygen) batteries have attracted considerable global attention in recent years due to their extremely high energy density (11,140 W·h·kg-1). The electrolyte is a key element in lithium-air batteries and the traditional organic electrolyte has great safety risk due to leakage. On the contrary, the polymer electrolyte has the advantages of high safety, high stability and easy processing comparing with the organic liquid electrolytes. In this paper, a new idea was proposed to coat the Nafion membrane on a layer of polymer for blocking the oxidation reduction electric (RM) and Li based on the selective permeability on lithium ion of the Nafion membrane. Self-made thicknesscontrollable Nafion membrane, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) and 2,2,6,6-tetramethylpiperidinooxy (TEMPO) were used to prepare a quasi solid polymer electrolyte (NSPE). Electrochemical workstation and LAND battery testing system were used to perform a galvanostatic charge/discharge test on Li-O2. The ionic conductivity of NSPE was 4.3×10-4 S·cm-1 at room temperature and the discharge platform was 2.6 V and the charging voltage was 3.7 V after 50 cycles with the cut-off capacity of 500 mA·h·g-1.
    Thermodynamic performance assessment of vacuum membrane-based dehumidification and air carrying energy radiant air-conditioning system (VMD-ACERS)
    Liang Chun, Guangcai Gong, Xi Fang, Pei Peng
    2021, 34(6):  217-227.  doi:10.1016/j.cjche.2020.11.022
    Abstract ( 93 )   PDF (1408KB) ( 155 )  
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    Temperature and humidity independent control (THIC) air-conditioning system is a promising technology. In this work, a novel temperature and humidity independent control (THIC) system is proposed, namely VMD-ACERS, which integrates vacuum membrane-based dehumidification and air carrying energy radiant air-conditioning system. This work establishes a novel coefficient of performance (COP) model of VMD-ACERS. The main parameters affecting the COP of conventional fan coil unit cooling system (FCUCS) and VMD-ACERS are investigated. The performance of FCUCS and VMD-ACERS are compared, and the energy-saving potential of VMD-ACERS is proved. Results indicate that, for FCUCS, the importance ranking of parameters is basically stable. However, for VMD-ACERS, the importance ranking will be affected by FCU and refrigerant. The most important parameters of VMD-ACERS are condensation temperature and permeate side pressure. On the contrary, superheating, subcooling are relatively less important parameters. For VMD-ACERS, it is not necessary to pursue the membrane with very high selectivity, because the selectivity of membrane would also be a less important parameter when it reaches 500. The COP of VMD-ACERS is higher than that of FCUCS when the permeate side pressure is higher than 8 kPa. The VMD-ACERS solves two technical problems about power-saving and thermal comfort of conventional THIC, and can extend the application of THIC air-conditioning system.
    Special Topic: Progress in Advanced Energy Technologies and Materials
    Special issue on progress in advanced energy technologies and materials
    Wenjin Ding, Xiaolei Fan
    2021, 34(6):  228-229.  doi:10.1016/j.cjche.2021.01.004
    Abstract ( 95 )   PDF (183KB) ( 96 )  
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    Preparation and water sorption properties of novel SiO2-LiBr microcapsules for water-retaining pavement
    Wenjing Li, Gilmore Wellio, Tiejun Lu, Changjun Zou, Yongliang Li
    2021, 34(6):  230-241.  doi:10.1016/j.cjche.2021.01.007
    Abstract ( 93 )   PDF (1114KB) ( 82 )  
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    Novel SiO2-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope (SEM), particle size analysis, and Fourier transform infrared spectroscopy (FT-IR). The water vapor sorption and desorption of the formulated microcapsules was then experimentally studied using dynamic vapor sorption (DVS), with the results fitted to three kinds of adsorption kinetics models. In addition, the specific surface area (SSA) was also calculated based on BET theory; and the thermal performance was investigated by laser flash analysis (LFA). Experimental results show a change of 103% in mass of the microcapsule sample under 90% relative humidity (RH) at 30 ℃ after water vapor sorption. The fitting of results indicates that the adsorption process is mainly governed by the intra-particle diffusion mechanism, followed by the pseudo-first-order adsorption process. In comparison with most conventional pavement materials, it is found that the SSA of the formulated microcapsules is much larger while the thermal conductivity is lower. The unique properties of the formulated SiO2-LiBr microcapsules have significant potential to take the edge off the urban heat island effect and reduce rutting when applied to water-retaining pavement materials.
    A power plant for integrated waste energy recovery from liquid air energy storage and liquefied natural gas
    Tongtong Zhang, Xiaohui She, Yulong Ding
    2021, 34(6):  242-257.  doi:10.1016/j.cjche.2021.02.008
    Abstract ( 103 )   PDF (1124KB) ( 62 )  
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    Liquefied natural gas (LNG) is regarded as one of the cleanest fossil fuel and has experienced significant developments in recent years. The liquefaction process of natural gas is energy-intensive, while the regasification of LNG gives out a huge amount of waste energy since plenty of high grade cold energy (-160℃) from LNG is released to sea water directly in most cases, and also sometimes LNG is burned for regasification. On the other hand, liquid air energy storage (LAES) is an emerging energy storage technology for applications such as peak load shifting of power grids, which generates 30%-40% of compression heat (~200℃). Such heat could lead to energy waste if not recovered and used. The recovery of the compression heat is technically feasible but requires additional capital investment, which may not always be economically attractive. Therefore, we propose a power plant for recovering the waste cryogenic energy from LNG regasification and compression heat from the LAES. The challenge for such a power plant is the wide working temperature range between the low-temperature exergy source (-160℃) and heat source (~200℃). Nitrogen and argon are proposed as the working fluids to address the challenge. Thermodynamic analyses are carried out and the results show that the power plant could achieve a thermal efficiency of 27% and 19% and an exergy efficiency of 40% and 28% for nitrogen and argon, respectively. Here, with the nitrogen as working fluid undergoes a complete Brayton Cycle, while the argon based power plant goes through a combined Brayton and Rankine Cycle. Besides, the economic analysis shows that the payback period of this proposed system is only 2.2 years, utilizing the excess heat from a 5 MW/40MWh LAES system. The findings suggest that the waste energy based power plant could be co-located with the LNG terminal and LAES plant, providing additional power output and reducing energy waste.
    Continuous generation of lattice oxygen via redox engineering for boosting toluene degradation performances
    Shiya He, Zhimin You, Xin Jin, Yi Wu, Cheng Chen, He Zhao, Jian Shen
    2021, 34(6):  258-266.  doi:10.1016/j.cjche.2020.07.050
    Abstract ( 106 )   PDF (2040KB) ( 72 )  
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    Excellent performances promoted by lattice oxygen have attracted wide attention for catalytic degradation of volatile organic compounds (VOCs). However, how to control the continuous regeneration of lattice oxygen from the support is seldom reported. In this study, we selected sepiolite supported manganese-cobalt oxides (CoxMn100-xOy) as model catalysts by tuning Co/(Co + Mn) mass ratio (x = 3%, 10%, 15%, and 20%) to enhance toluene degradation efficiency, owing to lattice oxygen regeneration by redox cycle existing at the interface and Mn species with high valence state, initiated by cobalt catalytic performance under the role of crystal field stability phase. The results of activity test show that the sepiolite-Co15Mn85Oy catalyst exhibit outperformances at 193 ℃ with 10,000 h-1 GHSV. In addition, the catalyst existed at the bottom of the “volcano” curve correlated T50 or T90 with Co/(Co + Mn) weight ratio is sepiolite-Co15Mn85Oy, conforming its outperformance. Further characterized by investigating active sites structural and electronic properties, the essential of superior catalytic activity is attributed to the grands of lattice oxygen continuous formation resulted from redox engineering based on the high atomic ratio of surface lattice oxygen with continuous refilled from the support and that of Mn4+/Mn3+ cycle initiated by cobalt catalytic behaviors. All in all, redox engineering, not only promotes grands of active species reversible regeneration, but supplies an alternative catalyst design strategy towards the terrific efficiency-to-cost ratio performance.
    Application of fracturing technology to increase gas production in low-permeability hydrate reservoir: A numerical study
    Peng-Fei Shen, Gang Li, Xiao-Sen Li, Bo Li, Jin-Ming Zhang
    2021, 34(6):  267-277.  doi:10.1016/j.cjche.2020.07.019
    Abstract ( 99 )   PDF (1363KB) ( 45 )  
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    Low temperature and low permeability are the challenges for the development of hydrate reservoirs in permafrost. The ice produced around the production well caused by high depressurization driving force reduces the gas production, and it is necessary to reduce the effect of ice production on gas production. In this work, a new combination of fracturing technology and depressurization method was proposed to evaluate the gas production potential at the site DK-2 in Qinghai-Tibet Plateau Permafrost. A relatively higher intrinsic permeability of the fracture zone surround the horizontal production well was created by the fracturing technology. The simulation results showed that the fracture zone reduced the blocking of production ice to production wells and promoted the propagation of production pressure. And the gas production increased by 2.1 times as the radius of the fracture zone increased from 0 to 4 m in 30 years. Nearly half of the hydrate reservoirs were dissociated in 30 years, and greater than 51.7% of the gas production was produced during the first 10 years. Moreover, production behaviours were sensitive to the depressurization driving force but not to the thermal conductivity. The growth of gas production was not obvious with the intrinsic permeability of the fracture zone higher than 100 mD. The effect of ice production on gas production by fracturing technology and depressurization method was limited.
    Catalytic performance improvement of volatile organic compounds oxidation over MnOx and GdMnO3 composite oxides from spent lithium-ion batteries: Effect of acid treatment
    Mingming Guo, Lizhong Liu, Jia-nan Gu, Hongbo Zhang, Xin Min, Jianxing Liang, Jinping Jia, Kan Li, Tonghua Sun
    2021, 34(6):  278-288.  doi:10.1016/j.cjche.2020.08.015
    Abstract ( 98 )   PDF (1424KB) ( 34 )  
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    In this work, cathode materials of spent lithium-ion ternary batteries are recovered and used as metal precursor to prepare multi-metal oxides MnOx(SY) and GdMnO3(SY) via combustion method and sol–gel method, respectively. Furthermore, a series of MnOx(SY)-n and GdMnO3(SY)-n (n = 0.05, 0.10, 1.00, 4.00, n represents the dilute HNO3 concentration) catalysts are fabricated by acid treatment of MnOx(SY) and GdMnO3(SY) samples and catalytic activities of oxygenated VOCs oxidation over all the prepared catalysts are investigated. Catalytic evaluation results show that acid-treated MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples perform the optimum VOCs removal efficiency respectively, which may be attributed to their obvious enhancement of physicochemical properties. In detail, MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples exhibit the larger specific surface area, bigger amount of surface high-valence metal ions (Mn4+, Co3+, Ni3+), more abundant adsorbed oxygen species and better low-temperature reducibility, which can play a crucial role in the significant improvement of VOCs oxidation. In situ DRIFTS results imply that the possible main intermediates are -OCO, -COO and -C-O species produced during VOCs oxidation. Possible by-products are further determined via TD/GC–MS analysis.
    Removal of lead (Pb(II)) and zinc (Zn(II)) from aqueous solution using coal fly ash (CFA) as a dual-sites adsorbent
    Widi Astuti, Achmad Chafidz, Ahmed S. Al-Fatesh, Anis H. Fakeeha
    2021, 34(6):  289-298.  doi:10.1016/j.cjche.2020.08.046
    Abstract ( 118 )   PDF (976KB) ( 118 )  
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    Coal fly ash (CFA) is composed of minerals containing some oxides in crystalline phase (i.e., quartz and mullite), as well as unburned carbon as mesoporous material, thus enabling CFA to act as a dual-sites adsorbent with unique properties. This work focused on the adsorption of Pb(II) and Zn(II) from binary system, a mixture containing two metal ion solutions present simultaneously, onto NaOH-modified CFA (MCFA). Several adsorption tests were conducted to evaluate the effect of several parameters, including pH and contact times. The experiment results indicated that chemical treatment of CFA with NaOH increased pore volume from 0.021 to 0.223 cm3·g-1. In addition, it could also enhance the availability of functional groups on both minerals and unburned carbon, resulting in almost 100% Pb(II) and 97% Zn(II) adsorbed. The optimum pH for adsorption system was pH = 3 and quasi-equilibrium occurred in 240 minutes. Equilibrium data from the experimental results were analyzed using Modified Extended Langmuir (MEL) and Competitive Adsorption Langmuir-Langmuir (CALL) isotherm models. The analysis results showed that the CALL isotherm model could better describe the Pb(II) and Zn(II) adsorption process onto MCFA in binary system compared with MEL isotherm model.
    Synthesis and characterization of caprolactone based polyurethane with degradable and antifouling performance
    Abid Ali, Lina Song, Jiankun Hu, Jingxian Jiang, Qingqing Rao, Muhammad Shoaib, Shah Fahad, Yongjie Cai, Xiaoli Zhan, Fengqiu Chen, Qinghua Zhang
    2021, 34(6):  299-306.  doi:10.1016/j.cjche.2020.11.007
    Abstract ( 130 )   PDF (1387KB) ( 60 )  
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    In this work, a degradable polyurethane composed of caprolactone (CL) and L-Lactide (LLA) as soft segments, and 4,4’-methylenebis(cyclohexyl isocyanate) (H12MDI) and polytetramethylene ether glycol (PTMEG) as hard segments, was prepared. Hydrolytic degradation experiment revealed that the degradable polyurethane (PU) could be degraded in artificial seawater. It also showed that caprolactone-copolyurethane (CL-PU) copolymer with higher crystallinity degraded much slower in artificial seawater. However, the introduction of LLA resulted in an increase in the hydrophilicity and reduction in the crystallinity of degradable PU, as demonstrated by the contact angle analysis. The result of the scanning electron microscope showed that the surface of degradable PU renewed under static condition. Moreover, degradable PU was able to be used as a carrier, and it controlled the release rate of 4, 5-dichloro-2- octyl-isothiazolone (DCOIT). The anti-diatom (Navicula incerta) test demonstrated that the (caprolactone-co-L-lactide)-co-polyurethane 4 (CL/LAx-PU4) with DCOIT contents prevented the adhesion of diatom Navicula incerta (88.37% reduction) due to their self-polishing and the release of antifoulants. Therefore, the degradable PU consisted of CL, LLA, and DCOIT could be a durable resin with good antifouling activity for the application in the marine anti-biofouling field.
    Materials and Product Engineering
    Synthesized graphene oxide and fumed aerosil 380 dispersion stability and characterization with partially hydrolyzed polyacrylamide
    Najeebullah Lashari, Tarek Ganat
    2021, 34(6):  307-322.  doi:10.1016/j.cjche.2020.09.035
    Abstract ( 112 )   PDF (5581KB) ( 65 )  
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    Hydrolyzed polyacrylamide (HPAM) is a commonly used polymer for the chemicals, mining and refining processes of hydrocarbon but suffers from a persistent high-temperature instability problem. In contrast, the nanoparticle suspension remains a technical challenge because of the strong interactions of van der Waal forces within nanoparticles, which always encourage aggregation. This research sought to improve nanoparticles (NP) stability and polymer (HPAM) rheological properties to improved hydrocarbon recovery by utilizing synthesized graphene oxide (GO) nanosheets and fumed Aerosil 380 Silica oxide (SiO2). The aqueous nanocomposites based on HPAM-GO and HPAM-SiO2 in aqueous polymeric solutions have been developed, and its viscoelastic and static behaviour is studied. The results imply that by adding fumed silica NP, the viscoelastic behaviour of HPAM is marginally improved, particularly in high temperatures and salinity, however, the inclusion of GO’s significantly improves the viscosity and stability of the base polymer fluid at high temperatures. The Fourier data for the transformation of the infrared spectrum confirmed that the hydrogen bonding formed between HPAM carbonyl groups and silica NP surface silanol functionality and covalent interlinking of electrostatic h-bonding between HPAM and functional GO contributed to the improved stabilization and improved rheological performance that helps to recover high salinity and temperature hydrocarbons.
    Functional monodisperse microspheres fabricated by solvothermal precipitation co-polymerization
    Fenghao Guo, Yuanyuan Ding, Yanyan Wang, Xiao Gao, Zhiyong Chen
    2021, 34(6):  323-331.  doi:10.1016/j.cjche.2020.09.036
    Abstract ( 106 )   PDF (719KB) ( 83 )  
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    Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization. We herein demonstrate that micro-sized monodisperse poly(methacrylic monomer-divinylbenzene) microspheres containing epoxy, lauyl, carboxyl and hydroxyl functions can be fabricated by solvothermal precipitation co-polymerization at 20% (mass) monomer loading with over 94% microsphere yield. The morphology and porosity of the obtained particles can be readily tuned by cosolvent-acetonitrile binary solvents. Addition of a small amount of cosolvent that has similar solubility parameter to that of the functional monomer can significantly improve the monodispersity of the obtained microspheres. When tetrahydrofuran was used as the co-solvent, the surface area of the highly porous microspheres achieved higher than 400 m2·g-1. Solvothermal precipitation co-polymerization can be expected in scale-up fabrication of various monodisperse functional microspheres free of any surfactant and additive.
    Effects of coagulation-bath conditions on polyphenylsulfone ultrafiltration membranes
    Zhenghui Liu, Jun Xiang, Xiaoli Hu, Penggao Cheng, Lei Zhang, Wei Du, Songbo Wang, Na Tang
    2021, 34(6):  332-340.  doi:10.1016/j.cjche.2020.11.038
    Abstract ( 132 )   PDF (1363KB) ( 167 )  
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    Polyphenylsulfone (PPSU) ultrafiltration membrane with different structures was prepared by nonsolvent-induced phase separation. The effects of coagulation bath conditions (concentration and temperature) on membrane morphology, pure water flux, pore size, porosity, and contact angle were studied and discussed based on ternary-phase diagrams. Results indicated that water had stronger coagulant power than ethanol, and that the morphology of the membrane prepared from the polyphenylsulfone/1-methyl- 2-pyrrolidinone/H2O (PPSU/NMP/H2O) system had finger-like structures. Conversely, sponge-like structures were observed for the PPSU/NMP/(NMP-H2O) and PPSU/NMP/(70NMP-EtOH-H2O) systems. Ethanol also greatly influenced on membrane structures. According to the Scanning electronic microscopy (SEM) image, the composition (mass fraction) of casting solution is 16% PPSU-84% NMP and the coagulation bath consisting of 70% NMP-26% H2O-4% C2H5OH. Meanwhile, the PPSU ultrafiltration membrane with spong-like was prepared under 8 ℃ coagulation bath. The formation of sponge-like structure reduces the pure water flux of ppsu membrane from 488.39 L·m-2·h-1 to 36.04 L·m-2·h-1. It also reduces the gas permeability, porosity, and pore size of the membrane. The addition of ethanol and NMP into the coagulation bath increases the roughness of the PPSU ultrafiltration membrane and reduces the hydrophilicity of the membrane.