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Table of Content
28 December 2019, Volume 27 Issue 12
    Food processing wastewater purification by microalgae cultivation associated with high value-added compounds production-A review
    Shuhong Li, Shuang Zhao, Siliang Yan, Yiting Qiu, Chunfeng Song, Yang Li, Yutaka Kitamura
    2019, 27(12):  2845-2856.  doi:10.1016/j.cjche.2019.03.028
    Abstract ( 320 )   PDF (2204KB) ( 273 )  
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    Microalgae have been considered as an efficient microorganism for wastewater treatment with simultaneously bioenergy and high value-added compounds production. However, the high energy cost associated with complicated biorefinery (e.g. microalgae cultivation, harvesting, drying, extraction, conversion, and purification) is a critical challenge that inhibits its large-scale application. Among different nutrition (e.g. carbon, nitrogen and phosphorous) sources, food processing wastewater is a relative safe and suitable one for microalgae cultivation due to its high organic content and low toxicity. In this review, the characteristic of different food wastewater is summarized and compared. The potential routes of value-added products (i.e. biofuel, pigment, polysaccharide, and amino acid) production along with wastewater purification are introduced. The existing challenges (e.g. biorefinery cost, efficiency and mechanism) of microalgal-based wastewater treatment are also discussed. The prospective of microalgae-based food processing wastewater treatment strategies (such as microalgae-bacteria consortium, poly-generation of bioenergy and value-added products) is forecasted. It can be observed that food wastewater treatment by microalgae could be a promising strategy to commercially realize waste source reduce, conversion and reutilization.
    A state-of-the-art review on single drop study in liquid-liquid extraction: Experiments and simulations
    Jiyizhe Zhang, Yundong Wang, Geoffrey W. Stevens, Weiyang Fei
    2019, 27(12):  2857-2875.  doi:10.1016/j.cjche.2019.03.025
    Abstract ( 265 )   PDF (3164KB) ( 123 )  
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    The experimental and numerical investigations of single drop in liquid/liquid extraction system have been reviewed with particular focus on experimental techniques and computational fluid dynamic simulation approaches. Comprehensive surveys of available experimental techniques and numerical approaches for single drop rising and falling were given. Subsequently, single drop mass transfer was also reviewed both experimentally and numerically. Additionally, single drop breakage and coalescence process and the influencing factors were summarized and compared, so as to establish sub-models for population balance model. Future directions on single drop mass transfer, drop breakage and coalescence were suggested. It is believed that the single drop is a powerful tool to assist extraction process design from lab-scale to pilot-scale.
    Fluid Dynamics and Transport Phenomena
    Thermal cracking characteristics of n-decane in the rectangular and circular tubes
    Zhiliang Lei, Bin Liu, Qin Huang, Kuo He, Zewei Bao, Quan Zhu, Xiangyuan Li
    2019, 27(12):  2876-2883.  doi:10.1016/j.cjche.2019.01.034
    Abstract ( 178 )   PDF (1333KB) ( 58 )  
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    To investigate the effect of regenerative cooling channel geometry on pyrolysis of endothermic hydrocarbon fuel, a series of supercritical pyrolysis experiments of n-decane in the rectangular and circular tubes were conducted. Moreover, sensitivity analysis of production of propylene and methane as well as CFD simulation were also done. The results showed that gas yield and conversion in the circular tube with an inner diameter of 2 mm had a similar tendency with the one of 1.5 mm in inner diameter. The conversion in the circular tube was much less than that in the rectangular tube at the same outlet temperature. The heat sink of the rectangular tube at the same outlet temperature was larger than that of circular tubes, but the temperature at the corner of the rectangular tube was relatively high. According to the experimental data of the test tubes, a correlation between the conversion and the temperature in the rectangular and circular tubes at the same outlet temperature was fitted, providing a reference for the design of regenerative cooling channels.
    Stochastic modeling of subgrid-scale effects on particle motion in forced isotropic turbulence
    Haoshu Shen, Yuxin Wu, Minmin Zhou, Hai Zhang, Guangxi Yue
    2019, 27(12):  2884-2891.  doi:10.1016/j.cjche.2019.05.007
    Abstract ( 159 )   PDF (2069KB) ( 26 )  
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    The subgrid-scale effects on particle motion were investigated in forced isotropic turbulence by DNS and priorLES methods. In the DNS field, the importance of Kolmogorov scaling to preferential accumulation was validated by comparing the radial distribution functions under various particle Stokes numbers. The prior-LES fields were generated by filtering the DNS data. The subgrid-scale Stokes number (StSGS) is a useful tool for determining the effects of subgrid-scale eddies on particle motion. The subgrid-scale eddies tend to accumulate particles with StSGS <1 and disperse particles with 1 < StSGS < 10. For particles with StSGS ≫ 1, the effects of subgrid-scale eddies on particle motion can be neglected. In order to restore the subgrid-scale effects, the Langevin-type stochastic model with optimized parameters was adopted in this study. This model is effective for the particles with StSGS >1 while has an adverse impact on the particles with StSGS <1. The results show that the Langevin-type stochastic model tends to smooth the particle distribution in the isotropic turbulence.
    Performance comparison of heat exchangers using sextant/trisection helical baffles and segmental ones
    Yaping Chen, Hongling Tang, Jiafeng Wu, Huaduo Gu, Shifan Yang
    2019, 27(12):  2892-2899.  doi:10.1016/j.cjche.2019.07.006
    Abstract ( 221 )   PDF (8771KB) ( 23 )  
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    The shell side flow fields of both sextant and trisection helical baffle heat exchangers are presented on meridian and multilayer hexagon slices. It verifies that the performance of sextant schemes is better than those of the other kinds of helical baffle heat exchangers. The main mechanisms are due to the restricted leakage flow in the minimized gaps with increased baffle number and by one row of tubes dampen the leakage flow in the circumferential overlapped area of the adjacent helical baffles. The performance features were simulated on two different angled sextant helical heat exchangers and each compared with two trisection ones of either identical helical pitch or identical incline angle. The results verified that the performances of helical heat exchangers are mainly determined by the helical pitch rather than the baffle incline angle. The average values of comprehensive index hoΔpo-1/3 of the trisection helical schemes T-24.1° and T-29.7° are correspondingly 3.47% and 3.34% lower than those of the sextant ones X-20° and X-25° with identical helical pitches. The comparison results show that the average values of shell side h.t.c. ho and comprehensive index hoΔpo-1/3 of the optimal dual helix sextant scheme DX30° are respectively 7.22% and 23.56% higher than those of the segment scheme S100.
    Separation Science and Engineering
    Thermal degradation of diethanolamine at stripper condition for CO2 capture: Product types and reaction mechanisms
    Idris Mohamed Saeed, Brahim Si Ali, Badrul Mohamed Jan, Wan Jefrey Basirun, Shaukat Ali Mazari, Ibrahim Ali Obid Birima
    2019, 27(12):  2900-2908.  doi:10.1016/j.cjche.2018.09.017
    Abstract ( 186 )   PDF (1978KB) ( 65 )  
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    Amine-based absorption/stripping is one of the promising technology for CO2 capture from natural and industrial gas streams. During the process, amines and CO2 undergo irreversible reactions to produce undesired compounds, which cause corrosion, foaming, increased viscosity and breakdown of equipment, ultimately contributing to the economic loss and environmental pollution. In this study, the thermal degradation of aqueous diethanolamine in the presence and absence of dissolved CO2 was investigated. The experiments were performed in stainless steel cylinders. The results show that thermal degradation in the absence of CO2 was a slow process; triethanolamine, and tris(2-aminoethyl)amine were only the degradation products identified in the mixture In addition, the rate of degradation was very low, only 3% degradation was observed after 4 weeks. But in the presence of CO2, sixteen degradation products were identified, nine of which were new degradation products reported for the first time in this study. The 3-(2-hydroxyethyl)-2-oxazolidinone, 1,4-bis(2-hydroxyethyl) piperazine and triethanolamine were the most abundant degradation products. The remaining DEA concentration after 4 weeks was about 20% of the total amine concentration. The most probable degradation reactions and their mechanisms are also proposed.
    Process design and economic analysis of methacrylic acid extraction for three organic solvents
    Jie Li, Zhijian Peng, Chunshan Li, Ping Li, Rafiqul Gani
    2019, 27(12):  2909-2916.  doi:10.1016/j.cjche.2019.02.014
    Abstract ( 215 )   PDF (2524KB) ( 49 )  
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    In this work, a techno-economic study for the solvent based extraction of methacrylic acid from an aqueous solution is presented. The involved phase equilibrium calculations in process design are verified by measured experimental data. First, experiments are conducted with different solvent candidates to measure LLE (liquid-liquid equilibrium) data and to establish the effects of extraction temperature and dosage of solvent. Next, the binary interaction parameters for the UNIQUAC model to be used for equilibrium calculations are fine-tuned with measured data. Then, a process for the solvent based extraction of methacrylic acid recovery is designed and verified through simulation with the regressed UNIQUAC model parameters. The optimal configuration of the process flowsheet is determined by minimizing the total annualized cost. Among the three solvent candidates considered-cyclohexane, hexane and toluene-the highest efficiency and the lowest total annualized cost is found with toluene as the solvent.
    Acid precipitation coupled electrodialysis to improve separation of chloride and organics in pulping crystallization mother liquor
    Zhaoyang Li, Rongzong Li, Zhaoxiang Zhong, Ming Zhou, Min Chen, Weihong Xing
    2019, 27(12):  2917-2924.  doi:10.1016/j.cjche.2019.07.002
    Abstract ( 165 )   PDF (5489KB) ( 76 )  
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    Inefficient separation of inorganic salts and organic matters in crystallization mother liquor is still a problem to industrial wastewater treatment since the high salinity significantly impedes organic pollutant degradation by oxidation or incineration. In the study, acidification combined electrodialysis (ED) was attempted to effectively separate Cl- ions from organics in concentrate pulping wastewater. Membrane's rejection rate to total organic carbon (TOC) was 85% at wastewater intrinsic pH=9.8 and enhanced to 93% by acidifying it to pH=2 in ED process. Negative-charged alkaline organic compounds (mainly lignin) could be liberated from their sodium salt forms and coagulated in acidification pretreatment. Neutralization of the organic substances also made their electro-migration less effective under electric driving force and in particular improved separation efficiency of chloride and organics. After acid-ED coupled treatment (pH=2 and J=40 mA·cm-2)[TOC] remarkably reduced from 1.315 g·L-1 to 0.048 g·L-1 and[Cl-] accumulated to 130 g·L-1 in concentrate solution. Recovery rate of NaCl was 89% and the power consumption was 0.38 kW·h·kg-1 NaCl. Irreversible fouling was not caused as electric resistance of membrane pile maintained stably. In conclusion, acidic-ED is a practical option to treat salinity organic wastewater when current techniques including thermal evaporation and pressure-driven membrane separation present limitations.
    Isolation and purification of carbazole contained in anthracene slag by extraction combined with medium pressure liquid chromatography
    Zhihao Ma, Xianyong Wei, Mingyao Zhou, Guanghui Liu, Fangjing Liu, Zhongqiu Liu, Xinyue Yu, Zhimin Zong
    2019, 27(12):  2925-2929.  doi:10.1016/j.cjche.2018.12.012
    Abstract ( 154 )   PDF (1573KB) ( 87 )  
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    Ultrasonic-assisted extraction (UAE) combined with medium pressure liquid chromatography (MPLC) was designed for carbazole separation from anthracene slag (AS). The effects of liquid/solid ratio, temperature, and extraction times on carbazole separation were investigated. When using CCl4 and ethyl acetate as extraction solvents and combining with MPLC, carbazole recovery and purity are 75.1% and 95.4%, respectively. The mechanism for carbazole separation were presumed by examining intermolecular interactions such as N-H…π, π-π, and C-Cl…π interactions. These results demonstrate that UAE/MPLC has a considerable potential as a green and promising strategy for separating and purifying carbazole and other chemicals from AS.
    Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid-nitric acid aqueous solution by strong acid cation resin
    Rui Lü, Qing Xi, Tan Li, Rui Li, Xiaochao Zhang, Jianxin Liu, Caimei Fan, Junqiang Feng, Lingyun Zhang, Zhihua Wang
    2019, 27(12):  2930-2936.  doi:10.1016/j.cjche.2018.12.025
    Abstract ( 157 )   PDF (552KB) ( 77 )  
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    The separation of Ca2+ and Mg2+ ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer. This paper studied the adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions by strong acid cation resin, and the effects of phosphoric acid and nitric acid on the adsorption process were investigated. The results reveal that the adsorption process of Ca2+ and Mg2+ ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1, respectively. The adsorption kinetics of Ca2+ and Mg2+ ions on resin fits better with the pseudo-first-order model, and the adsorption equilibrium in pure water is reached within 10 min contact time, while at the present of phosphoric acid, the adsorption rate of Ca2+ and Mg2+ ions on resin will go down. The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution, but the dynamic operation should control the flow rate of mix acid solution. Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.
    Liquid-liquid two-phase mass transfer characteristics in a rotating helical microchannel
    Yan Cao, Jun Li, Yang Jin, Jianhong Luo, Yubin Wang
    2019, 27(12):  2937-2947.  doi:10.1016/j.cjche.2018.12.026
    Abstract ( 242 )   PDF (3355KB) ( 37 )  
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    In this work, the mass transfer characteristics of two immiscible fluids were investigated in a rotating helical microchannel with hydraulic diameter of 932 μm. Aqueous phosphoric acid solution and 80% tri-n-butyl phosphate (TBP) in kerosene were selected for the investigation of mass transfer performance in quartz glass/high density polyethylene (HDPE) microchannel. High dispersion between the two immiscible fluids can be obtained in the microchannel due to the intensifying action of centrifugal force, and the majority of the droplets with average diameter of 20-100 μm were produced in the microchannel. The flow rate and rotation speed were found to have great effects on the extraction efficiency and average residence time. The empirical correlation of average residence time based on experimental data was developed by theoretical analysis and data fitting method, and a mathematical model of the mass transfer coefficient in dispersed phase was proposed.
    Catalysis, kinetics and reaction engineering
    Aminolysis of ethyl acetate in continuous flow and its reaction kinetics
    Tao Shen, Bo Ouyang, Chao Qian, Xinzhi Chen
    2019, 27(12):  2948-2952.  doi:10.1016/j.cjche.2019.03.015
    Abstract ( 252 )   PDF (527KB) ( 34 )  
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    The aminolysis of ethyl acetate was promoted significantly via continuous reaction in a tubular reactor. N-propylacetamide was thus synthesized without presence of solvent and catalyst. The optimum conditions were obtained as follows:the reaction temperature is 218℃, the reaction pressure is 3.5 MPa, the molar ratio (ethyl acetate:N-propylamine) is 1:1, and the residence time is 350 min. Accordingly, the conversion of ethyl acetate is up to 94.8%. Furthermore, the kinetics of the rapid reaction stage (when the conversion of ethyl acetate is 20%-80%) can be expressed as lnk--4629:44 1/T + 2:1366, and the apparent activation energy is Ea=38489 J·mol-1.
    Synthesis, characterization and catalytic methanation performance of modified kaolin-supported Ni-based catalysts
    Jiao Liu, Chuanyue Zheng, Junrong Yue, Guangwen Xu
    2019, 27(12):  2953-2959.  doi:10.1016/j.cjche.2019.04.009
    Abstract ( 227 )   PDF (1126KB) ( 66 )  
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    Kaolin as a raw material for mesoporous support was firstly modified by calcination, acid treatment, and then was used to prepare nickel catalysts. The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different. XRD pattern of the kaolin calcined at 600℃ or 900℃ exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100℃ showed obvious peaks for γ-Al2O3. Therefore, the nickel-based catalysts exhibited different physic-chemical properties. Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 > CA-900 > CA-1400 > CA-600 > KA ≈ 0 at temperatures of 350-650℃ and a space velocity of 120 L·g-1·h-1. Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation.
    The nature of the deactivation of hydrothermally stable Ni/SiO2-Al2O3 catalyst in long-time aqueous phase hydrogenation of crude 1,4-butanediol
    Haitao Li, Yin Zhang, Hongxi Zhang, Xiaoqin Qin, Yalin Xu, Ruifang Wu, Zheng Jiang, Yongxiang Zhao
    2019, 27(12):  2960-2967.  doi:10.1016/j.cjche.2019.03.008
    Abstract ( 115 )   PDF (1814KB) ( 41 )  
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    The deactivation of Ni/SiO2-Al2O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated. During the operation time of 2140 h, the catalyst showed slow activity decay. Characterization results, for four spent catalysts used at different time, indicated that the main reason of the catalyst deactivation was the deposition of carbonaceous species that covered the active Ni and blocked mesopores of the catalyst. The TPO and SEM measurements revealed that the carbonaceous species included both oligomeric and polymeric species with high C/H ratio and showed sheet. Such carbonaceous species might be eliminated through either direct H2 reduction or the combined oxidation-reduction methodologies.
    Process Systems Engineering and Process Safety
    Explosion limits estimation and process optimization of direct propylene epoxidation with H2 and O2
    Mengke Lu, Yanqiang Tang, Wenyao Chen, Guanghua Ye, Gang Qian, Xuezhi Duan, Weikang Yuan, Xinggui Zhou
    2019, 27(12):  2968-2978.  doi:10.1016/j.cjche.2019.01.015
    Abstract ( 221 )   PDF (4442KB) ( 72 )  
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    Direct propylene epoxidation with H2 and O2, an attractive process to produce propylene oxide (PO), has a potential explosion danger due to the coexistence of flammable gases (i.e., C3H6 and H2) and oxidizer (i.e., O2). The unknown explosion limits of the multi-component feed gas mixture make it difficult to optimize the reaction process under safe operation conditions. In this work, a distribution method is proposed and verified to be effective by comparing estimated and experimental explosion limits of more than 200 kinds of flammable gas mixture. Then, it is employed to estimate the explosion limits of the feed gas mixture, some results of which are also validated by the classic Le Chatelier's Rule and flammable resistance method. Based on the estimated explosion limits, process optimization is carried out using commercially high and inherently safe reactant concentrations to enhance reaction performance. The promising results are directly obtained through the interface called gOPT in gPROMS only by using a simple, easy-constructed and mature packed-bed reactor, such as the PO yield of 13.3%, PO selectivity of 85.1% and outlet PO fraction of 1.8%. These results can be rationalized by indepth analyses and discussion about the effects of the decision variables on the operation safety and reaction performance. The insights revealed here could shed new light on the process development of the PO production based on the estimation of the explosion limits of the multi-component feed gas mixture containing flammable gases, inert gas and O2, followed by process optimization.
    Fuzzy comprehensive assessment of running condition for a large-scale centrifugal compressor set
    Yanji Sun, Yanqiu Pan, Zhongliang Zhou, Xin Li
    2019, 27(12):  2979-2988.  doi:10.1016/j.cjche.2019.03.013
    Abstract ( 112 )   PDF (4420KB) ( 37 )  
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    A fuzzy comprehensive assessment method of running condition was constructed and applied to a large-scale centrifugal compressor set in a petrochemical corporation aiming at the monitoring and early warning of abnormal conditions in industry. The maximal information coefficient (MIC) correlation analysis of indexes was introduced to determine the independent indexes to be assessed, and the dynamic deterioration degree was calculated using the predicted independent indexes by the second-order Markov chain model. The fuzzy membership degree weighting method was employed to assess the running condition of all units in the set. Simple and direct radar chart was used to visualize condition assessment grades. Results showed that the proposed fuzzy comprehensive assessment method successfully assessed the running condition of the set. The constructed method achieved 10 min earlier alarm than the traditional threshold alarm occurred at the specific moment of 00:44 on April 7 of 2018. The method would provide a valuable tool and have a wide engineering application in ensuring the safety and reliability of industrial production.
    Chemical Engineering Thermodynamics
    Thermodynamic data calculation for iron phases in sulfoaluminate cementitious materials prepared using solid wastes
    Wenlong Wang, Guolin Li, Lizhi Zhou, Changzai Ren
    2019, 27(12):  2989-2993.  doi:10.1016/j.cjche.2019.01.010
    Abstract ( 142 )   PDF (309KB) ( 33 )  
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    The preparation of sulfoaluminate cementitious materials (SCM) is a promising way to massively utilize solid wastes. Iron phases are significant in SCM system but the thermodynamic data of some key minerals, such as 6CaO·Al2O3·2Fe2O3 (C6AF2) and 6CaO·2Al2O3·Fe2O3 (C6A2F), are missing, which greatly hinders the SCM optimization in a theoretical way. This work, for the first time, calculated the standard formation enthalpy, Gibbs free energy of formation, entropy and molar heat capacity for C6AF2 and C6A2F and lowered the errors to the least with the reference of C4AF data in the literature. By building the function diagram of Gibbs free energy changes with temperature for the basic iron phase formation reactions with the obtained thermodynamic data, it is proved that the formation likeliness of C6AF2 is higher than that of C6A2F, as is accordant to the literatures and verifies the correctness of obtained data. This work provides a good theoretical foundation to optimize SCM mineral system and to study relevant mechanism deeply.
    Densities and viscosities for ionic liquids [BMIM][BF4] and [BMIM][Cl] and their binary mixtures at various temperatures and atmospheric pressure
    Jinlong Li, Hong Zhu, Changjun Peng, Honglai Liu
    2019, 27(12):  2994-2999.  doi:10.1016/j.cjche.2019.04.016
    Abstract ( 198 )   PDF (425KB) ( 48 )  
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    The density and viscosity of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] and 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and their binary mixtures within the temperatures from 303.15 K to 323.15 K and at ambient pressure were determined in this work. The temperature dependences of density and viscosity were satisfactorily described with the linear model and the Vogel-Tammann-Fulcher type equation, respectively. The molar volume and viscosity of binary IL mixtures were predicted through ideal mixing rules showing that almost null deviations for IL mixtures were observed and their mixing was remarkably close to linear ideal behavior in the molar volumes, while comparatively large errors in viscosity occurred. Additionally, the molar volume of the investigated pure ILs and their mixtures could well be predicted by a predictive model presented by Valderrama et al. (Fluid Phase Equilib., 275 (2009) 145).
    Solubility and mass transfer of H2, CH4, and their mixtures in vacuum gas oil: An experimental and modeling study
    Zhigang Lei, Yifan Jiang, Yao Liu, Yichun Dong, Gangqiang Yu, Yanyong Sun, Ruili Guo
    2019, 27(12):  3000-3009.  doi:10.1016/j.cjche.2019.05.010
    Abstract ( 146 )   PDF (1322KB) ( 23 )  
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    In this work, the solubility data and liquid-phase mass transfer coefficients of hydrogen (H2), methane (CH4) and their mixtures in vacuum gas oil (VGO) at temperatures (353.15-453.15 K) and pressures (1-7 MPa) were measured, which are necessary for catalytic cracking process simulation and design. The solubility of H2 and CH4 in VGO increases with the increase of pressure, but decreases with the increase of temperature. Henry's constants of H2 and CH4 follow the relation of ln H=-413.05/T + 5.27 and ln H=-990.67/T + 5.87, respectively. The molar fractions of H2 and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients. The results showed that with the increase of pressure, the liquid-phase mass transfer coefficients increase. Furthermore, the solubility of H2 and CH4 in VGO was predicted by the predictive COSMO-RS model, and the predicted values agree well with experimental data. In addition, the gas-liquid equilibrium (GLE) for H2 + CH4 + VGO system at different feeding gas ratios in volume fraction (i.e., H2 85% + CH4 15% and H2 90% + CH4 10%) was measured. The selectivity of H2 to CH4 predicted by the COSMO-RS model agrees well with experimental data. This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.
    Energy, Resources and Environmental Technology
    Optimization of the N2 generation selectivity in aqueous nitrate reduction using internal circulation micro-electrolysis
    Zhijuan Niu, Sitao Zhang, Yanhe Han, Mengmeng Qi
    2019, 27(12):  3010-3016.  doi:10.1016/j.cjche.2018.12.007
    Abstract ( 172 )   PDF (2973KB) ( 30 )  
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    The reduction of nitrate using internal circulation micro-electrolysis technology (ICE) was investigated. The effect of the reaction time, initial pH, Fe/C ratio, and aeration rate on the nitrate reduction was investigated using a single factor experiment. Based on the results of the single factor experiment, a response surface methodology (RSM) was applied to optimize the N2 generation selectivity. The effects and interactions of three independent variables were estimated using a Box-Behnken design. Using the RSM analysis, a quadratic polynomial model with optimal conditions at pH=8.8, Fe/C=1:1, and an aeration rate of 30 L·min-1 was developed by means of the regression analysis of the experimental data. Using the RSM optimization, the optimal conditions yielded a N2 generation selectivity of 72.0%, which is in good agreement with experimental result (73.2%±0.5%) and falls within the 95% confidence interval (IC:66.8%-77.3%) of the model results. This indicates that the model obtained in this study effectively predicts the N2 generation selectivity for nitrate reduction by the ICE process, thus providing a theoretical basis for process design.
    Effect of gas composition on nitric oxide removal from simulated flue gas with DBD-NPC method
    Lan Yang, Xiang Zhang, Qing Kan, Binran Zhao, Xiaoxun Ma
    2019, 27(12):  3017-3026.  doi:10.1016/j.cjche.2019.01.026
    Abstract ( 150 )   PDF (6792KB) ( 29 )  
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    A new method for nitric oxide (NO) removal was developed by combining dielectric barrier discharge (DBD) and negative pulse corona (NPC). The effects of gas composition (O2, CO2, and H2O) on NO removal were investigated with this method, and the effect of alcohols (methanol and ethanol) addition on NO removal was also investigated as well as the reaction mechanisms to enhance the NO removal efficiency. The experimental results showed that O2, CO2, and H2O had obvious inhibition effects on NO removal, and the negative effects were in the following order:O2 > CO2 > H2O. The addition of methanol or ethanol in the reaction system could mitigate the negative effects of O2, CO2, and H2O on NO removal, and also eliminated the production of NO2. The positive effect of alcohols addition with DBD-NPC denitration method was also validated in the simulated flue gas, in which the NOx (NO, NO2) was mainly converted into N2.
    Materials and Product Engineering
    Relationship between equilibrium potential and radius of lanthanides electrolyzed on the zinc cathode
    Peng Li, Milin Zhang, Debin Ji, Min Qiu, Li Liu
    2019, 27(12):  3027-3035.  doi:10.1016/j.cjche.2019.02.011
    Abstract ( 141 )   PDF (6341KB) ( 46 )  
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    The electrochemical behavior of lanthanide elements deposited on liquid zinc cathodes was studied using cyclic voltammetry (CV) and open circuit chronopotentiometry (OCP). We observed a "bimodal effect" in the equilibrium deposition potentials of zinc with lanthanides. A mathematic equation is derived to illustrate the relationship between the equilibrium potential of the intermetallic compounds formed by lanthanide elements and zinc and their atomic radius. This equation is not only applicable to lanthanide elements but also hold for other elements such as alkali metal lithium, alkaline earth metal magnesium, calcium and transition metal niobium, which have crucial theoretical significance for the electrolysis of intermetallic compounds, the separation, and extraction of metals.
    Controlling pore structures of Pd-doped organosilica membranes by calcination atmosphere for gas separation
    Yibin Wei, Hengfei Zhang, Jiaojiao Lei, Huating Song, Hong Qi
    2019, 27(12):  3036-3042.  doi:10.1016/j.cjche.2019.03.021
    Abstract ( 101 )   PDF (3471KB) ( 29 )  
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    Pd-doped organosilica membranes were prepared by controlling calcination atmospheres (i.e. POS-Air, POS-N2, POS-H2, POS-H2/N2) to tailor their networks for improving their gas separation performance. This study shows that Pd (II) could be only maintained under non-reductive calcination atmosphere, while inert and reducing calcination atmosphere is more beneficial to maintain organosilica moieties in POS networks. POS-H2/N2 membrane showed the optimal H2 separation performance that its permselectivities for H2/CO2, H2/N2, H2/CH4 and H2/SF6 are 15.0, 96.7, 173.0 and 3400.0, respectively. Moreover, it is found that H2 molecules pass through the four membranes based on activated diffusion, while CO2 molecules permeation through POS-N2 and POS-Air membrane is dominated by surface diffusion. This work may provide insight into the understanding of the calcination atmosphere effect on gas separation performance of metal-doped organosilica membranes.
    Preparation and characterization of a novel antibacterial acrylate polymer composite modified with capsaicin
    Jianhui Zhou, Xiaotong Zhang, Ying Yan, Jianfeng Hu, Hang Wang, Yan Cai, Jinqing Qu
    2019, 27(12):  3043-3052.  doi:10.1016/j.cjche.2019.03.024
    Abstract ( 162 )   PDF (2526KB) ( 75 )  
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    A novel antibacterial acrylate polymer composite modified with capsaicin was successfully synthesized by a two-step reaction. Capsaicin and acryloyl chloride were firstly esterified, and then applied to solution polymerization with acrylate monomers and styrene. The yield of the esterified products was about 85.3%. The polymer was characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), contact angle (CA) and antibacterial ring tests. The number-average molecular weight (Mn) of the polymer was 27214, based on the capsaicin-acrylate dosage of 6.5 wt%. The TGA revealed a stable thermal property. The contact angles of the polymers films on tinplate increased from 77.5° to 86.2° with the increasing amount of capsaicin-acrylate. The antibacterial tests demonstrated excellent antimicrobial capability of the polymers.
    Synthesis plasmonic Bi/BiVO4 photocatalysts with enhanced photocatalytic activity for degradation of tetracycline (TC)
    Nianjun Kang, Dongbo Xu, Weidong Shi
    2019, 27(12):  3053-3059.  doi:10.1016/j.cjche.2019.05.008
    Abstract ( 114 )   PDF (1872KB) ( 54 )  
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    In recent years, the excessive use of antibiotics has become a serious problem for human health. BiVO4 regarded as one of the most promising visible-light-driven photocatalysts was used to degrade the antibiotics. In this paper, we fabricated Bi/BiVO4 plasmonic photocatalysts which enhanced the photocatalytic activity of BiVO4 for degradation of tetracycline (TC) antibiotic. The Bi/BiVO4 photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy. In addition, the photocatalytic experiment results show that the 0.04-Bi/BiVO4 sample has the best photocatalytic activity for 2 times than the pure BiVO4 photocatalyst. The cycle experiments, after four repetitions of the experiments, showed the sample still maintained a high photocatalytic activity. Finally, the photocatalytic reaction mechanism was also studied by free radical capture experiments and electron paramagnetic resonance spectroscopy.