CIESC Journal

Topologic group space method for estimating normal boiling point enthalpy of vaporization and boiling point

WEI Wenying;KONG Haining;XU Wen;HAN Jinyu

2006, 57(4): 710-714.

Abstract ( 682 )

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A space design for the molecule of organic compounds based on the traditional group division method was made, and a topologic group space method for estimating physical properties of organic compounds was proposed by using the group module index to characterize the group position in the molecule. Expressions for estimating enthalpy of vaporization at normal boiling point ΔH_vb and boiling point T_b were established, with the numerical values of relative group parameters obtained by fitting data from 503 and 669 organic compounds respectively. The average percentage deviations of vaporization enthalpy ΔH_vb and boiling point T_b estimation were 0.962% and 1.40% respectively. An extensive comparison between the proposed method and other widely used methods showed that the new method had wider applicability and higher accuracy.

Adsorption of erythromycin on macroporous resins and thermodynamic analysis

SONG Yinghua;ZHU Jiawen;CHEN Kui;WU Bin

2006, 57(4): 715-718.

Abstract ( 829 )

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Experiments were carried out to study the adsorption of erythromycin(EM) in aqueous solutions on macroporous resins. The adsorption equilibrium characteristics of three types of macroporous resins, XAD7HP,XAD16 and HZ816 were evaluated. The adsorption data were correlated with the Freundlich isotherm equation. The correlation results were in good agreement with experimental data. Thermodynamic calculation and analysis showed that the process of adsorption of EM was an endothermic physical process. The entropy of the system increased in the course of adsorption.

Model of contact heat transfer in granular moving bed

WU Jintao;CHEN Jizhong;YANG Yongrong

2006, 57(4): 719-725.

Abstract ( 607 )

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The heat transfer in granular materials can be found in many industrial processes,but such phenomenon is not well understood. A particle contact heat transfer model (PCHM) was developed by taking independent mechanisms into account. The model combined with discrete element methods(DEM)was used to simulate heat transfer between particles and inserted heating surface. Comparing the mechanisms with each other showed that, the heat conduction through contact area had the greatest contribution to apparent effective quantity of heat transfer Q_eff. The key factors effecting Q_eff include the number of particles contacting with heating wall,contact time, and contact area. When the average diameter was the same, the diameter distribution had little effect on heat transfer. When the average diameter was different, the effective heat transfer coefficient decreased with increasing particle diameter. The quantity of heat transfer was spatially nonuniform.

Boiling heat transfer on composite powder porous surface tubes

LIU Along;XU Hong;WANG Xuesheng;ZHOU Jianxin;HOU Feng;WANG Chen

2006, 57(4): 726-730.

Abstract ( 566 )

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Sintered porous coating of composite powder was applied on heat transfer tube. An experiment on enhanced boiling heat transfer with composite powder porous surface tubes was carried out, which used deionized water in tube to heat and boil acetone out of tube. The coefficient of boiling heat transfer, K and geometric parameters were measured and compared with the experimental results of a smooth tube and other domestic porous surface tubes. The resistance to fouling of porous surface tubes was also studied. The results indicated that porosity was the most important factor for the coefficient of boiling heat transfer of porous surface tubes. The coefficient of boiling heat transfer of porous surface tubes obtained in this paper could reach 14 times of that of smooth tubes at the same condition and porous surface tubes had the capability of resistance to fouling, which provides scientific data for the commercialization of that type of porous surface tubes.

Phenomenon of cavity and its size in rectangular movingbed

CHEN Yunhua;ZHU Xuedong;WU Yongqiang;DONG Yanhe;ZHU Zibin

2006, 57(4): 731-737.

Abstract ( 567 )

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Moving bed is widely used in industry, but the range of the velocity of cross-flow gas is limited by a phenomenon of “cavity”，which was investigated in a two-dimensional rectangular moving bed. The formation,developments of cavities in the moving bed were investigated and described with two particle materials and materials of wall. And the relationship between the size of a cavity and the velocity of cross-flow gas was investigated.A cavity could be created when the velocity of cross-flow gas or the pressure gradient was high enough, and the size of a cavity increased with the increase of cross-flow gas velocity.Based on force balance,a simplified nonlinear equation group with multiple physical parameters that affect the size of a cavity was developed and the cavity size vs cross-flow gas velocity relationship thus obtained agreed with experimental data.

Catalytic combustion of methane over Ce_1-xCu_xO_2-x/Al₂O₃ solid solution catalysts

YIN Fengxiang;JI Shengfu;CHEN Nengzhan;ZHAO Liping;WANG Wei;LI Chengyue;LIU Hui

2006, 57(4): 744-750.

Abstract ( 718 )

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In this study, Ce1-xCuxO2-x/Al2O3（x=0—1）solid solution catalysts and Ce0.2Cu0.8O1.2/Al2O3 catalysts with different Ce0.2Cu0.8O1.2 loading were prepared with the co-impregnation method. The catalysts were characterized by means of X-ray diffraction（XRD）and temperature-programmed reduction（TPR）. It was found that some of the Ce1-xCuxO2-x/Al2O3 catalysts exhibited high activity for catalytic combustion of methane because of the formation of the solid solution which promoted the dispersion of Cu, and changed redox property of the catalyst.There existed synergetic effect between CeO2 and CuO and the mole ratio of Ce to Cu influenced the activity of the catalyst.

Overgrowth of mesoporous MCM-41 on zeolite Y

ZHANG Haijuan;LI Yongdan

2006, 57(4): 751-756.

Abstract ( 663 )

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The deep hydrodearomatization and desulfurization of diesel fuel is a very challenging task by conventional hydrotreating processes using conventional catalyst support. Based on the molecular dimensions for typical aromatics and sulfur-containing compounds in diesel fuel, a pore structure design was proposed for sulfur-tolerant catalysts used in the second stage for aromatics reduction. A novel molecular sieve composite Y overgrown with a thin layer of mesoporous MCM-41 was prepared. The as-synthesized samples were characterized with various techniques. The results indicated that this composite was different from the mechanical mixture of MCM-41 and NaY. The composite possessed a mesopore system as well as a microporous structure of zeolite Y. Moreover, the mesopore wall of the composite was built of a lot of secondary building units characteristic of zeolite Y, which was quite different from the amorphous nature of MCM-41 in the mechanical mixture. The hydrothermal stability was improved.

Unsteady-state operation of trickle-bed reactor

LIU Guozhu;MI Zhentao

2006, 57(4): 757-761.

Abstract ( 633 )

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The influences of the various unsteady-state operating modes, such as the operation under pulsing regimes, periodic packing mode and periodic feed, on the performance of the trickle-bed reactor (TBR) were investigated experimentally by using the hydrogenation of 2-ethylanthraquinone over Pd/Al₂O₃ as a model reaction on a laboratory-scale TBR. It was found that the mass space-time yields of TBR was increased by 50% under pulsing regimes due to the enhancement of inter-phase mass transfer, which was confirmed by apparent kinetics research. The mass space-time yield of catalyst was increased by 40% for using the periodic packing mode due to the significant enhancement of gas-liquid mass transfer rates under the interested conditions. The periodic operation of TBR, which improved inter-phase mass transfer and eliminated the external static liquid holdup, increased conversion and selectivity by 10%.

Characterization of supported heteropoly acid (salt) and its catalytic behavior in synthesis of fructone

ZHANG Fumin;YUAN Chaoshu;REN Xiaoqian;WANG Jun

2006, 57(4): 762-768.

Abstract ( 697 )

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A series of 12-phosphotungstic acid(PW)and its cesium salt catalysts immobilized on various supports such as ultra-stable Y zeolite (USY), dealuminated USY (DUSY), SiO2 and SBA-15 were prepared. Their specific surface area and acid strength were measured, and their catalytic performance was evaluated in the synthesis of fructone by acetalization of ethyl acetoacetate with ethylene glycol. The high catalytic activity was found over the prepared supported heteropoly compound catalysts in this reaction. However, for the supported PW catalysts, a severe leaching of heteropoly anions into water was observed, leading to their poor reusability. By contrast, the Cs salt of PW catalyst supported on DUSY exhibited very high catalytic activity with high water tolerance and reusability. The conversion of ethyl acetoacetate of 98.7% with the selectivity of fructone above 97% could be obtained over 30%Cs2.5H0.5PW/DUSY under the optimal reaction conditions.

Physicochemical properties of TiO₂-SiO₂ composite oxide and their effects on diesel hydrorefining performance

ZHANG Shaojin;ZHOU Yasong;XU Chunming

2006, 57(4): 769-774.

Abstract ( 679 )

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A series of TiO2-SiO2 composite oxides, with different Ti/Si atomic ratios, were obtained by using the sol-gel method combined with the CO2 supercritical fluid drying (SCFD) method. The effects of the Ti/Si atomic ratio and calcination temperature on the properties of TiO2-SiO2 composite oxides, including specific surface area, pore structure, acidity and atomic coordination, were studied. The hydrodesulfurization(HDS) property of catalysts supported on TS-1 and TS-4 was investigated by using the residual fluid catalytic cracking(RFCC) diesel oil as feedstock. The experimental results showed that the pore structure stability and crystalline state stability of TiO2 modified by SiO2 increased dramatically. The acidity and interaction between the atoms of the TiO2-SiO2 varied with Ti/Si atomic ratio. The crystalline state and acidity of supports influenced the HDS property of catalysts. The presence of anatase TiO2 in the TiO2-SiO2, strengthened the interaction of the supports and active metals, and enhanced the HDS activity of the catalysts. The different acidic sites of catalysts showed different HDS properties to different type of sulfur compounds. The catalysts with a larger number of Bronsted acidic sites showed better HDS performance for the simple structure sulfur compounds. On the contrary, the catalysts with a larger number of Lewis acidic sites showed better HDS performance for the complicated structure sulfur compounds.

Methanol steam reforming on Pd/ZnO catalysts

WANG Yanhua; XU Hengyong;ZHANG Jingchang

2006, 57(4): 775-779.

Abstract ( 691 )

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The steam reforming of methanol on Pd/ZnO catalysts prepared by co-precipitation was studied in a stainless reactor under various conditions. The effects of Pd loading, reduction temperatures, reaction temperatures, weight hourly space velocity (WHSV) and molar ratio of water to methanol on the steam reforming of methanol to hydrogen were investigated. The results showed that when the mass fraction of metallic palladium was 15.9%, reaction temperature was 523—573 K, reduction temperature was 523—573 K, molar ratio of water to methanol was 1.0—1.2 and WHSV was 17.2 h^-1, higher methanol conversion, higher CO₂ selectivity, higher hydrogen yield and lower outlet CO molar fraction were achieved. The stability tests over 15.9% Pd/ZnO and the commercial CuO/ZnO/Al₂O₃ catalyst were made at 573 K. The results showed that the methanol conversion over 15.9% Pd/ZnO remained constant for 8 h without deactivation. On the contrary, the methanol conversion over CuO/ZnO/Al₂O₃ catalyst gradually decreased with time on stream by 14.4%. So Pd/ZnO catalysts display better stability.

Preparation and characterization of CNT-supported cobalt catalysts for 1-octene hydroformylation

ZHANG Hongzhe, WANG Xiuna, LI Jiawei, QIU Jieshan

2006, 57(4): 780-784.

Abstract ( 922 )

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Carbon nanotube-supported cobalt catalysts were prepared by using three techniques including impregnation method (IP), metal organic chemical vapor deposition method (MOCVD) and modified ethylene glycol method (EG). The size distribution of Co metal particles on Co/CNTs was studied with XRD and TEM. It was found that the Co/CNT catalysts prepared by MOCVD had high and homogeneous dispersion of spherical Co metal particles with a narrow particle-size distribution in the range of 5—10 nm centering around 7.5 nm, which is consistent with the calculated value 7.1 nm obtained by Scherrer formula from the XRD data. For the hydroformylation of 1-octene, the Co/CNT catalysts prepared by MOCVD were superior to those prepared by other methods and showed significantly higher activity and regioselectivity.The excellent catalytic performance could be attributed to homogeneous distribution and small size of cobalt metal particles.

Reaction of methanol as part of FCC feedstock

PAN Shuyu;JIANG Hongbo;WENG Huixin

2006, 57(4): 785-790.

Abstract ( 653 )

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The feasibility analysis of integrating methanol to oil(MTO) with FCC process is based on their similarities and compatibility. Feeding methanol as part of FCC feedstock is proposed to produce more light olefins. According to the characteristics of FCC, the effects of reaction temperature, methanol solution feed, and the coke content of catalyst were studied systematically. The experimental result testified the higher light olefins yields from methanol under FCC condition. The results showed that the highest hydrocarbon yield and its light olefins proportion were 26.3%—28.1％(mass) and 67.8%—66.5％(mass) respectively, on the equilibrium catalyst and 40%(mass) methanol solution feed at 550—600℃. The reaction characteristics of methanol conversion under FCC condition was proposed. The results provide important reference for the process of feeding methanol as part of FCC feedstock.

Characterization and catalytic properties of highly effective Ti-ZSM-5 zeolite prepared by gas-solid reaction

LIU Min;GAO Jian;GUO Xinwen;WANG Xiangsheng;LI Can;FENG Zhaochi

2006, 57(4): 791-798.

Abstract ( 836 )

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B-ZSM-5 zeolite with a smaller crystal size and a suitable amount of framework boron was synthesized by modifying hydrothermal synthesis temperature.Ti-ZSM-5 zeolite was prepared by the gas-solid reaction of acid-treated B-ZSM-5 with gaseous TiCl₄.The samples were characterized by SEM,XRD,FT-IR,UV-Raman and UV-Vis.The performance of Ti-ZSM-5 in phenol hydroxylation was investigated.The results showed that the smaller sized Ti-ZSM-5 samples had MFI topology structure and high crystallinity, higher content of framework titanium and no extra-framework titanium.The optimal reaction conditions of phenol hydroxylation over Ti-ZSM-5 were as follows: acetone as solvent, reaction temperature 343—363 K, the mass ratio of catalyst to phenol 5.0%—10.0%, the molar ratio of phenol to hydrogen peroxide 3—6,reaction time 3—6 h.Phenol conversion could be more than 23%.

Preparation of molybdenum carbide catalyst and its hydrodesulfurizationperformance for thiophene

JIN Guangzhou;ZHU Jianhua;JU Huliang;SUN Guida;GAO Junbin

2006, 57(4): 799-804.

Abstract ( 618 )

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Molybdenum carbide catalysts were prepared by temperature-programmed reaction using CH4/H2 gas mixture to carburize molybdenum trioxide at different temperatures, then were characterized with XRD and BET. TG-DTA in-situ approach was used to investigate the carburizing reaction of MoO3 in CH4/H2.The catalytic performance of molybdenum carbide catalysts was evaluated for hydrodesulfurization by using 5%(vol) thiophene as the model reactant under the conditions of 300—370℃, 3.0 MPa and space velocity 6 h-1. The results indicated that molybdenum carbide catalysts possessed much higher thiophene HDS activity than MoS2, and the HDS conversion of thiophene reached 98% at 370℃. It was also found that the BET surface area of molybdenum carbide catalysts decreased and more free carbon deposited on the catalyst surface with increasing carburizing temperature.Furthermore the HDS activity for thiophene decreased. The carburizing reaction pathway of MoO3 in CH4/H2 was MoO3→MoO2→MoOxCy→Mo2C, and the proper carburizing temperature was 675℃ as determined by experiment in this paper.

Effect of copper chloride hydroxide on catalytic synthesis of diethyl carbonate by oxidative carbonylation of ethanol

ZHANG Zhen;ZHANG Jing;WANG Shengping;MA Xinbin

2006, 57(4): 805-809.

Abstract ( 613 )

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The effects of different crystal structures of copper chloride hydroxide on the catalytic synthesis of diethyl carbonate by the oxidative carbonylation of ethanol was discussed. The catalytic activity was improved significantly and the active component of γ-Cu₂(OH)₃Cl was partially converted into Cu(OH)Cl when KCl was added in the catalyst. CO-TPD analysis of the catalyst showed that the adsorption of CO increased and the desorption temperature shifted to the right. Morphological analysis by SEM of the catalyst showed that the active component of the catalyst was highly dispersed on the carrier promoting the catalytic activity of the catalyst in the synthesis of DEC. Reaction mechanism analysis showed that the fact that Cu(OH)Cl was more active than γ-Cu₂(OH)₃Cl in the oxidative carbonylation of ethanol to DEC was attributed to the John-Teller effect.

Kinetic model of polystyrene degradation in supercritical toluene

HUANG Ke;TANG Lihua;ZHU Zibin;YING Weiyong

2006, 57(4): 810-814.

Abstract ( 642 )

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The degradation of polystyrene in supercritical toluene was studied at 310—370℃, 3.6—5.2 MPa by using a novel fast reactor. Supercritical solvents have unique properties such as excellent heat and mass transfer. Compared with thermal degradation without solvents, supercritical degradation obtains high conversion in a very short reaction time. The supercritical degradation of polystyrene is a typical free radical reaction mechanism, including chain fission, disproportionation, radical recombination, β-scission, intermolecular abstraction and intramolecular abstraction. Based on the reaction mechanism, the process of polystyrene degradation in supercritical toluene was modeled at the mechanistic level by using population balance equations formulated via the method of moments. The predictions of the degradation conversion of polystyrene were compared with experimental results, and the agreement was good.

Effect of preparation by ultrasound-assisted impregnation on properties of CuO/CeO₂/γ-Al₂O₃ catalysts for catalytic combustion of VOCs

GUO Jianguang;LI Zhong;XI Hongxia;XIA Qibin

2006, 57(4): 815-820.

Abstract ( 611 )

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CuO/CeO2/γ-Al2O3 catalysts were prepared by both an ultrasound-assisted impregnation method and by a conventional impregnation method. The catalytic combustion of two volatile organic compounds (VOCs), toluene and benzene, was carried out by using these CuO/CeO2/γ-Al2O3 catalysts. The surface properties of these catalysts were characterized with X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the ignition temperature and total conversion temperature of the VOCs on the CuO/CeO2/γ-Al2O3 catalysts prepared by ultrasound-assisted impregnation were much lower than those on the CuO/CeO2/γ-Al2O3 catalysts prepared by conventional impregnation, and the activity of the CuO/CeO2/γ-Al2O3 catalysts prepared by ultrasound-assisted impregnation was much higher than that of the CuO/CeO2/γ-Al2O3 catalysts prepared by conventional impregnation. XRD results showed that the use of ultrasound improved the dispersion of Cu ions on the surface of the CuO/CeO2/γ-Al2O3 catalysts.XPS results indicated that the use of ultrasound promoted the distribution of active components on the surface of the CuO/CeO2/γ-Al2O3 catalysts and increased the Cu+ content on the surface of the catalysts so that the activity of the catalysts for VOCs combustion can be enhanced.

Direct synthesis of hydrogen peroxide via hydrogen-oxygen plasma

ZHOU Juncheng;GOU Jianxia;CHEN Lixing;GUO Hongchen;WANG Xiangsheng

2006, 57(4): 821-823.

Abstract ( 649 )

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The effects of the diameter of high-voltage electrode wire, the voltage of discharge, the structure of reactor and the total flow rate of H2-O₂ feed on the direct synthesis of hydrogen peroxide in ambient conditions by the dielectric barrier discharge (DBD) plasma method were studied.The results showed that the diameter of high-voltage electrode wire, the voltage of discharge and the structure of reactor had pronounced effects on H₂O₂ synthesis. By using a self-designed DBD plasma reactor (recycled flowing electrolyte as grounding electrode), H₂O₂ was synthesized with 32.51% yield at room temperature and atmospheric pressure from H₂-O₂ feed, which was several times higher than that reported in literature.

Demulsification of liquid paraffine W/O emulsion by freezing and thawing

LIN Chang;HE Gaohong;LI Xiangcun;LIU Hongjing

2006, 57(4): 824-831.

Abstract ( 723 )

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The demulsification of water in oil(W/O)emulsion by freeze/thaw is a new physical demulsification method.By far, the demulsification process and mechanism are still unclear.By using a stable liquid paraffin emulsion as the object of study, the freeze/thaw demulsification process of W/O emulsion with a highly viscous continuous phase(oil phase) was studied with differential scanning calorimeter (DSC) and optical microscope.The results showed that the freeze/thaw demulsification was a gradual process.When the droplet was smaller than 5.5 μm, the emulsion system could be demulsified by several freeze/thaw cycles, and in the freeze/thaw cycles firstly the small droplets coalesced and grew, and then separated from the emulsion system.But when the droplet was larger, such as 51 μm, the demulsification would be complete only in one freeze/thaw cycle, with over 90%(vol) of demulsification ratio.In addition, it was found that the increase of water content was beneficial to demulsification efficiency.And it is the droplet size, not the water content affects the freezing point of water phase.When the droplet is larger, the freezing point temperature declines with the decrease of droplet size,the effect is not obvious when the droplet was smaller than 5.5 μm.

Enhancement effects of mechanically milling facilities on dissolution of Panzhihua ilmenite

LI Chun; CHEN Shengping;WU Zibing;GUO Linghong;LIANG Bin

2006, 57(4): 832-837.

Abstract ( 689 )

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The mechanical activation of Panzhihua ilmenite with tumbling ball mill, planetary ball mill and stirring ball mill, and the dissolution of activated ilmenite were investigated. Milling operation considerably accelerated the leaching reaction of ilmenite in dilute sulfuric acid solutions. Samples activated with stirring ball mill exhibited the highest leaching activity and those activated with planetary ball mill the second, while those activated with tumbling mill showed the least activity improvement. Characterization results suggested that the enhancement of ilmenite leaching was due to the increasing lattice strain in c axis direction of the ilmenite crystal cells. Milling with stirring ball mill produced more fine particles, larger lattice strain in c axis direction, and higher surface activity. It apparently accelerated dissolution.The enhancement effect on leaching reaction relied not only on the strength but also the form of the mechanical force applied.

Pervaporative separation of benzene/cyclohexane mixture using graphite-filled PVA membranes

PENG Fubing;JIANG Zhongyi

2006, 57(4): 838-842.

Abstract ( 602 )

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Graphite-filled poly-vinyl alcohol(CG-PVA) membranes were prepared by the solution blending method and characterized with FTIR, SEM and XRD methods. The results showed that graphite was uniformly distributed in the membrane matrix, there was stronger interaction between PVA and graphite particle, the crystallinity of the membranes decreased after the incorporation of graphite. The swelling and sorption properties of CG-PVA membranes in benzene/cyclohexane mixtures were investigated. The free volume properties of CG-PVA membrane were analyzed by positron annihilation lifetime spectroscopy, and apparent fractional free volume was calculated, which showed the same tendency of charge as permeation flux. Finally, the effect of graphite content and particle size on pervaporation properties were investigated. The pervaporation results indicated that the CG-PVA membranes exhibited good separation properties for benzene/cyclohexane mixtures, and the benzene flux and separation factor could reach 90.7 g•m^-2•h^-1 and 100.1, respectively, for benzene/cyclohexane［50/50,%(mass)］mixtures.

Pervaporation separation of phenol aqueous solution using cyclodextrin polymer-filled PDMS membranes

FANG Zhiping;JIANG Zhongyi

2006, 57(4): 843-848.

Abstract ( 871 )

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The PDMS and CDP-filled PDMS membranes were prepared by the phase inversion approach using polydimethylsiloxane as precursor, tetraethyl orthosilicate as crosslinker, dibutyltin dilaurate as catalyst and chloroform or heptane as solvents. Pervaporation separation of phenol aqueous solution using unfilled PDMS and CDP-f-PDMS membranes was investigated. It was demonstrated that the separation performance of PDMS membranes was improved by incorporating CDP into PDMS membrane. The effects of solvent type and filling amount of CDP on pervaporation properties were examined. The effects of the operation parameters including feed temperature, feed flow rate and feed concentration on pervaporation properties were also investigated. The permeation flux and separation factor could be 34.5 g•m^-2•h^-1 and 10.3 when the experimental temperature was 67℃ and the filling amount is 2%.

Recovery of nanometer nickel catalyst with ceramic membrane

ZHONG Zhaoxiang;CHEN Rizhi;XING Weihong;XU Nanping

2006, 57(4): 849-852.

Abstract ( 586 )

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Ceramic membranes were used to recover nanometer nickel catalyst in the preparation of p-aminophenol.In order to resolve the problem of adsorption loss of nanometer nickel in the pilot plant, inert particles were added to the suspension. As a result, adding inert particles such as micro or submicro oxides was proven to be effective.They could alleviate the adsorption loss of nanometer nickel particles and shorten the time of reaching steady state of nickel concentration without affecting the activity of the catalyst and permeate flux.

Artificial neural network approach to predict solubility of paroxetine hydrochloride hemihydrate in various solvents

REN Guobin;WANG Jingkang;YIN Qiuxiang;XU Zhao

2006, 57(4): 853-860.

Abstract ( 751 )

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Modeling and prediction of solubility is a key to develop polymorph crystal growth and crystallization process. In this paper,by using a laser monitoring observation technique, solubilities of paroxetine hydrochloride hemihydrate in various solvents were determined by the synthetic method and a multiparameter artificial neural network (ANN) approach was used to predict the solubility of solute in different solvents. The ANN predicted the logarithmic solubility of paroxetine hydrochloride hemihydrate with average error of 0.7%. The results showed that artificial neural network could be useful when no data is available.

Modified MILP model for scheduling of sequential multipurpose batch plants

PAN Ming;QIAN Yu;LI Xiuxi

2006, 57(4): 861-866.

Abstract ( 678 )

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Sequential multipurpose batch processes are common in many fine chemical manufacturing plants, such as traditional paint, food, pharmaceuticals,and specialty chemicals plants. The investigation in this paper includes analyzing the operational features of sequential multipurpose batch plants, decomposing the overall batch process spatially into several sub-systems, and presenting a modified MILP formulation for the scheduling of sequential multipurpose batch plants with continuous-time approaches. As the bi-index binary variables are substituted for the tri-index binary variables in the MILP model, the number of discrete variables decreases substantially. The new model is effective in solving large scale scheduling problems. In case studies, the proposed model was compared with the previous model presented by Voudouris and Grossmann. Moreover, several large scale scheduling problems were solved successfully with the proposed modeling approaches. These case studies prove the validity of the model and the practicability of the proposed approaches.

Synthesis of water utilization networks with mass load uncertainty based on fuzzy programming

LIU Yongjian;YUAN Xigang;LUO Yiqing

2006, 57(4): 867-873.

Abstract ( 714 )

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An improved symmetric fuzzy linear programming (SFLP) model was developed for fresh water minimization of single-component water utilization networks with mass load uncertainty. A multi-objective mixed-integer SFLP and a main criterion limiting (MCL) solution strategy were further developed for designing the networks. Three example problems were solved and the results demonstrate that the proposed modeling and solution procedures are suitable for solving the problems of optimum synthesis of water utilization networks with mass load uncertainty, and could avoid effectively degenerate solutions and then provide an optimum design for the networks.

Preparation of monodispersed O/W emulsions containing monomer by SPG membrane emulsification

XIE Rui;CHU Liangyin;CHEN Wenmei

2006, 57(4): 874-879.

Abstract ( 828 )

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Monodispersed oil-in-water (O/W) emulsions containing monomer terephthaloyl dichloride (TDC) were prepared by Shirasu-porous-glass (SPG) membrane emulsification method, and the factors influencing the emulsification process were experimentally investigated. The results showed that to prepared monodisperse O/W emulsions by SPG membrane emulsification, it was more important to choose an anionic surfactant than to consider hydrophile-lipophile balance (HLB) matching. Both the monodispersity and stability of emulsions could be improved by increasing the viscosity of disperse phase or continuous phase. With increasing monomer concentration inside the disperse phase, the monodispersity of emulsions became slightly worse and the mean diameter of emulsions gradually became smaller. Monodisperse monomer-containing emulsions were obtained when the SPG membrane pore size was larger than 1.0 μm; however, when the SPG membrane pore size was smaller than 1.0 μm, no monodisperse emulsions were obtained because of the formation and chokage of p-phthalic acid (TPA) crystals in the pores of the SPG membrane. With increasing emulsification time, the average emulsion diameter generally decreased, and the monodispersity of emulsions gradually became worse.

Effects of lpdA gene knockout on metabolism of Escherichia coli with different carbon sources and aeration conditions

LI Mai;YAO Shanjing;Shimizu Kazuyuki

2006, 57(4): 880-885.

Abstract ( 906 )

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Lipoamide dehydrogenase encoded by lpdA gene is the subunit of pyruvate dehydrogenase complex,α-ketoglutarate dehydrogenase complex and glycine cleavage multi-enzyme systems. In the present study, the comparison of the fermentative properties between lpdA knockout E. coli and the wild type was made with different carbon sources and aeration conditions. Furthermore, the effect of lpdA gene knockout on the metabolism of E. coli was studied based on the measurement of some key enzyme activities and the intracellular metabolite concentrations. The results showed that under aerobic condition, using glucose as a carbon source, the knockout of lpdA gene led to the accumulation of pyruvate, D-lactate and L-glutamate; the repression of the TCA cycle; the activation of the glyoxylate shunt and the glucose-6-phosphate dehydrogenase in the oxidative pentose phosphate pathway. These conclusions were reinforced by the fermentation using acetate or pyruvate as a carbon source under aerobic condition and the fermentation using glucose as a carbon source under microaerobic condition.

Ferric(Ⅲ)immoblized collagen fiber and its adsorption for bacteria

LU Aixia;JIAO Limin;LIAO Xuepin;YAO Kai;ZHOU Rongqing;SHI Bi

2006, 57(4): 886-891.

Abstract ( 729 )

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A novel adsorbent, ferric(Ⅲ) immobilized collagen fiber, was prepared, and its adsorption behavior to bacteria was studied. Ferric was uniformly dispersed in collagen fiber mainly through chemical connection and could withstand the extraction of water. It was found that the ferric(Ⅲ) immobilized collagen fiber exhibited high adsorption capacity to bacteria. The adsorption capacity to E. coli and S. aureus were 2.04×10⁹cfu•g^-1 and 3.15×10⁹ cfu•g^-1at 30℃ when the adsorption experiments were carried out for 1 h and their initial concentration were 1.02×10⁷cfu•ml^-1 and 9.8×10⁶ cfu•ml^-1 respectively. The adsorption isotherms could be described by the Freundlich equation. The adsorption capacity was influenced by culture age of the bacteria, but no considerable change was observed at varying temperature and pH. Further analysis indicated that the adsorption kinetics data could be well fitted by the pseudo-second-order rate model, and adsorption capacities calculated by the model were consistent with the actual measurements with error≤2%. In addition, the quite fast adsorption rate of bacteria on ferric(Ⅲ) immobilized collagen fiber was probably due to the fact that the adsorption process took place at the surface of adsorbent.

Modeling for size distributions of flocculating yeast cell flocs during continuous ethanol fermentation

GE Xumeng;BAI Fengwu

2006, 57(4): 892-897.

Abstract ( 971 )

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The focused beam reflectance measurement probe (FBRM) was directly inserted into a stirred fermentor, and the size distributions of self-flocculating yeast strain SPSC01, a fusant from Saccharomyces cerevisiae and Schizosaccharomyces pombe for ethanol fermentation, was online monitored.In a simulated system composed of the floc-buffer suspensions, it was found that the floc size distributions could be characterized by a lognormal function.The characteristic parameter,M,could be correlated with the stirring speed of fermentor,r, by a logarithmic function.Therefore, the designated size distributions of the flocs could be achieved by controlling the stirred speed. Interference by CO₂ bubbles generated during cell metabolism was observed in a real yeast floc ethanol fermentation system.The floc chord length distribution was measured with the FBRM for intrinsic kinetics investigation during which the floc size needed to be controlled at a level of micrometer scale to eliminate inner mass transfer limitations. Using the established model, the CO₂ bubbles interference was climinated by data processing to give the floc size distributions.

Synthesis of 3-oxo-4-aza-5-androstene-17-oxime derivatives

YANG Xiongwen;ZHU Kongming;LIU Dongzhi;ZHOU Xueqin

2006, 57(4): 898-901.

Abstract ( 594 )

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4-Azasteroids as important 5α-reductase inhibitors play a critical role in therapy of several human endocrine diseases, such as benign prostatic hyperplasia, male pattern baldness, female hirsutism, etc. Starting from 4-androstenedione, three novel 3-oxo-4-aza-5-androstene-17-oxime derivatives 7, 8 and 9 were synthesized through oxidation ring cleavage, amination ring closure, oximation,and substitution. The structures of these novel compounds were identified with MS,1H NMR and 13C NMR.

ERK-like MAP kinase regulated by O^-₂· during Ce⁴⁺-induced apoptosis of cultured Taxus cuspidata cells

YANG Song;GE Zhiqiang;YUAN Yingjin

2006, 57(4): 902-907.

Abstract ( 749 )

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Ce⁴⁺ at 1 mmol·L^-1 induces apoptosis of suspension cultures of Taxus cuspidata cells;however，the underlying signal regulation of superoxide anions (O^-₂·) and extracellularly-responsive kinase (ERK)-like MAP kinase is unknown. It was shown that an approximately 46×103 ERK-like MAP kinase appeared to be activated in 5 min，and a significant activity increase was detected in 60 min，reaching 2.1-fold higher than that of the control cells. ERK-like activity remained at this high level until 120 min，and started to diminish within 240 min. By the 240th minute the activity reached about 43% of control value，and in 48 h declined to 25%. Ce⁴⁺-induced O^-₂·transient burst，and the first peak appeared in about 3.7—4 h，the second peak appeared in about 7 h.The burst of O^-₂· was effectively suppressed by the application of diphenyl iodonium (DPI) at 5 μmol·L^-1 or 10 μmol·L^-1.The inhibition of O^-₂· production increased and prolonged ERK-like activity. ERK-like activity increased by about 7.3 and 18.8-fold of control value in 60 min，and reached about 9.6 and 10.5-fold in 240 min. These results suggested that it was possible that ERK-like activation and O^-₂· burst were separate signal events in early times. O^-₂· burst formed signal negative regulation to ERK-like activity. Down-regulation of ERK-like partly participated in mediating apoptotic signal transduction.

Microencapsulation of methyl salicylate by utilizing yeast cell

WANG Jinyu;LI Shufen;TIAN Songjiang

2006, 57(4): 908-911.

Abstract ( 763 )

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The microcapsule of methyl salicylate（MS）was prepared by utilizing dried yeast(S. cerevisiae)cell deactivated by pretreating as wall material. The effects of encapsulating temperature,MS to yeast ratio and encapsulating time on the microencapsulation of MS were investigated. The results showed that the yield of encapsulated MS could reach 48.58% under the conditions of encapsulating temperature of 70℃,MS to yeast ratio of 2 ml•g^-1 and encapsulating time of 6 h. By means of the novel pharmaceutical microencapsulation, the process was simple and efficient and was free from contamination by organic solvent.

Fabrication of microporous ceramic supports for enzyme immobilization

HUANG Lei;CHENG Zhenmin

2006, 57(4): 912-918.

Abstract ( 665 )

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A new method was developed for the fabrication of porous ceramics by using the special three-dimensional reticulate framework formed by the groups of flocculent raw particles in the deposit. The size of pore diameter could be controlled between micron and nanometer scale. For the former, the pore diameter was about 10 to 100 μm, the apparent porosity ranged from 53 % to 59 %,the bulk density from 0.97 to 1.10 g•cm^-3, and the crushing strength above 6.0 MPa; for the latter, measured by the mercury intrusion method, the average pore diameter was about 76 nm, and the total surface area 5.90 m2•g^-1. With commercial Penicillium expansum lipase(PEL) as model enzyme, the performance of the porous ceramic supports was investigated in relation to the activity and stability of immobilized enzyme. The results indicated that the microporous ceramics prepared by the present method could potentially be better inorganic supports for enzyme immobilization than some other commercial inorganic solid supports like silica gel, diatomite and active carbon, on the condition that its pore surface was suitably modified according to the property of the enzyme.

Differential protein analysis during Maituolaimysin production process using two-dimensional gel electrophoresis and MALDI-TOF MS

WANG Yuxia;QIAO Jianjun;YUAN Yingjin

2006, 57(4): 919-921.

Abstract ( 544 )

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Total protein extraction of Streptomyces luteogriseus in different fermentation times was analyzed in order to discover the enzymes associated with Maituolaimysin biosynthesis, make the biosynthesis pathway clear, and enhance its production. Two-dimensional gel electrophoresis analysis showed that 8 proteins were up-expressed, 5 were down-expressed, 6 were new-expressed and 6 disappeared in the protein extraction of 48 h compared with that of 36 h. Fifteen of the different expression proteins were analyzed by Matrix-Assisted Laser Desorption Ionization(MALDI)Time-of-Flight(TOF) mass spectrum and 4 of them were identified. Among the 4 identified proteins, one was involved in protein biosynthesis; one was associated with Streptomyces differentiation; one was a key enzyme in TCA circle and another one was a hypothetical protein whose function was unknown.Investigation of the function of these identified proteins suggested that they all had direct or indirect relations to Maituolaimysin biosynthesis, and especially, the protein Clp2 could accelerate the differentiation of Streptomyces, which would directly result in Maituolaimysin biosynthesis.

Transformation methods of alkalophilic Bacillus pseudofirmus

LIU Minsheng;XING Xinhui

2006, 57(4): 922-926.

Abstract ( 769 )

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Aiming at development of transformation methods for alkalophilic Bacillus pseudofirmus JCM 9141 (growth at pH>10), screening conditions of transformants by using antibiotics were first examined to overcome the antibiotic inactivation at high pH. Then, different transformation methods including competent cells, protoplast and electroporation were studied, respectively. The transformation efficiencies of competent cells and protoplast were low, while a modified electroporation method achieved higher transformation efficiency under 3000 V•cm^-1. This method was also applicable to other alkalophilic Bacillus sps.

Wet flue gas desulfurization by organic acid-enhanced coarse limestone

LIU Shengyu;LIU Xiaofei;XIAO Wende

2006, 57(4): 927-931.

Abstract ( 703 )

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A new wet FGD process in which SO₂ was absorbed in the bubble reactor using granular limestone and acetic acid was proposed. The main difference as compared with the conventional wet FGD process was to utilize granular limestone directly as desulphurization reagent with simultaneous addition of acetic acid. Thus, the pulverization of limestone, which causes power consumption, could be saved. By using granular limestone（165—200 μm） directly as absorbent only without acetic acid, SO₂ removal efficiency and limestone utilization were too low,60.7% and 44% respectively.By adding 10—30 mmol•L^-1 acetic acid,desulphurization was increased to 95% and limestone utilization was enhanced to 93.5%.The desulphurization efficiency and limestone utilization of using fine limestone were 88% and 92.9% respectively under the same operating conditions.The buffer capacity of system was also enhanced by adding organic acid. With concentrations of 5 and 10 mmol•L^-1 acetic acid, it took 45 min for the pH value to drop from 6.0 to 4.0.Furthermore, with increasing organic acid concentration the effect of buffer action was more obvious. It could better adapt to the fluctuation of SO₂ concentration of flue gas,make operation more flexible, and improve process reliability. The mechanism of promoting SO₂ absorption by acetic acid was suggested.

Preparation of nanocrystalline Pd modified p-Si electrode and its hydrogen evolution property under illumination

LI He;YAO Suwei;ZHANG Weiguo;WANG Hongzhi;BEN Yuheng

2006, 57(4): 932-936.

Abstract ( 688 )

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Nanocrystalline Pd modified p-Si electrode (Pd/p-Si) was prepared by electroless deposition on p-Si. The structure and morphology were determined by XRD and SEM respectively. The results showed that the structure of Pd coatings was nanocrystalline and Pd particles with different sizes were obtained by controlling time.The average diameter of Pd particles was about 80 nm at deposition time of 20 min. The catalytic properties of the Pd/p-Si electrode for hydrogen evolution under illumination and in darkness were studied with the constant current polarization method. The results showed that the hydrogen evolution reaction (HER) potential of the Pd/p-Si electrode under illumination was 250 mV lower than that in darkness, and was 450 mV lower than that of p-Si electrode in darkness at current density of 2.5 mA•cm^-2. The results of electrochemistry A.C. impedance spectra (EIS) indicated that the electrochemistry HER resistance of the Pd/p-Si electrode decreased from 593.12 Ω•cm² to 442.20 Ω•cm² under illumination，and its HER rate increased evidently.

Synthesis and characterization of non-stoichiometric spinel as anode for rechargeable lithium-ion battery

TIAN Congxue;ZHANG Zhao;HOU Jun; LI Hai

2006, 57(4): 937-942.

Abstract ( 745 )

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The precursors of non-stoichiometric spinel Li _1.05 Co _0.05 Ni _0.05 Mn _1.9 O _3.9 F _0.1 were prepared by coprecipitation, supersonic irradiation coprecipitation,the Pechini method and high temperature solid phase reaction separately according to adulteration of anion-cation combination, then the precursors were treated by three-step heat-treatment , i. e. pre-annealing at 650℃, annealing at 780℃ and backfiring at 550℃. The content of manganese and the average chemical valence in spinel were determined by volumetric analysis, and the as-prepared powders were characterized with granularity distribution, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance test. The results showed that the content of manganese and the average chemical valence fitted well with the theoretical value.In contrast with the products prepared by coprecipitation,the Pechini method and high temperature solid phase reaction, the product synthesized by supersonic irradiation coprecipitation had the narrowest granularity distribution,and the smallest volumetric surface area (0.96 m²•g^-1).The intensity value of XRD was the highest, so was its crystallinity, and its lattice constant was 0.821 nm and grain size was 57.78 nm according to the Scherrer equation. The powders prepared by supersonic irradiation coprecipitation had higher capacity and static cycle life by capacity test than that of the three others which was only reduced by 9.3% after 30 cycles.

Removing NO with triglycine cobalt solution

ZHOU Chunqiong;DENG Xianhe;PAN Zhaoqun

2006, 57(4): 943-947.

Abstract ( 777 )

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According to the high NO removal feature of Co(en)³⁺₃, triglycine cobalt was chosen to absorb and catalytically oxidize NO thanks to the similar coordination structures of triglycine cobalt and Co(en)³⁺₃. Ethylene diamine was replaced by glycine to prevent its volatility and difficult transport.It was observed that the NO removal was influenced by the initial concentration of triglycine cobalt, absorption reaction pH value and temperature. The NO removal was enhanced by the rise of triglycine cobalt initial concentration. The optimum pH was neutral or weakly basic. The optimum absorption reaction temperature was 50℃. The addition of urea could increase the ability of triglycine cobalt to simultaneously remove NO and SO2,for urea could accelerate the oxidation of SO^2-₃.

Thermo-sensitive and separation properties of poly(N-isopropylacrylamide) hydrogels with enhanced surface crosslinking

HUANG Jian;HUANG Zhiming;BAO Yongzhong;SHAN Guorong;WENG Zhixue

2006, 57(4): 948-952.

Abstract ( 736 )

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To improve the separation efficiency of thermo-sensitive poly(N-isopropylacrylamide) (PNIPA) hydrogels, an inverse suspension polymerization process was used to prepare PNIPA hydrogels by using ammonium persulfate and N,N,N′,N′-tetramethylethylenediamine as a pair of redox initiators, and N,N′-methylene bisacrylamide (BIS) and divinylbenzene (DVB) as the multiple crosslinking agents. The morphology, thermo-sensitivity and the application to the separation of poly(ethylene oxide) glycol (PEG) aqueous solution of the resultant PNIPA hydrogels were investigated. It was found that the obtained hydrogels were in the form of beads with a rather compact structure and had a lower critical solution temperature (LCST) of 32℃. The separation efficiency increased with the increase of the molecular mass or with the decrease of the concentration of PEG. Increasing the amount of crosslinking agents could also improve the separation efficiency, and the introduction of hydrophobic DVB was an effective way to improve the separation efficiency without the loss of swelling ratio of hydrogels.

Nucleation efficiency of substituted aromatic heterocyclic phosphoric acid metal salts as nucleators for isotactic polypropylene

ZHANG Yuefei;XIN Zhong

2006, 57(4): 953-958.

Abstract ( 693 )

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Nucleation efficiency of 2,2′-methylene-bis (4,6-di-tert-butylphenyl)phosphoric acid metal salts as the nucleators for isotactic polypropylene (iPP) were investigated with differential scanning calorimeter (DSC), their effects on mechanical and optical properties of iPP were also studied. The results showed that monovalent metal salts of substituted aromatic heterocyclic phosphoric acid such as sodium salt, lithium salt and potassium salt had good nucleation efficiency. With 0.2%(mass) of sodium salt, lithium salt and potassium salt blended with iPP, the crystallization peak temperature of PP could be increased by 13.5℃, 13.6℃ and 15.0℃, respectively, the mass fraction of crystallinity of iPP could be increased by about 5%, and crystallization rate was enhanced increasingly.Meanwhile the tensile strength and flexural modulus of iPP could be increased by about 10% and 30%, respectively,and the haze value of iPP could be decreased by about 40%. But bivalent and trivalent metal salts of the phosphoric acid had little effect on properties of iPP. Furthermore the studies on non-isothermal crystallization kinetics of iPP showed that the addition of sodium salt, lithium salt and potassium salt could change the crystallization growth pattern of iPP.

Preparation, characterization and application as light scattering agents of micron-size polystyrene/polysiloxane core/shell microspheres

LU Xin;XIN Zhong

2006, 57(4): 959-963.

Abstract ( 688 )

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Micron-size polystyrene(PS)/polysiloxane microspheres with core/shell structure were synthesized.Firstly, polystyrene microspheres were prepared by conventional dispersion polymerization in an ethanol-water medium. Secondly, methyl trimethoxylsilane was hydrolyzed, mixed with the polystyrene core microspheres and then condensed to generate polysiloxane shells in the surface of PS microspheres by adding an aqueous NH₄OH as catalyst. The shape, size distribution, surface composition and thermo decomposition of core/shell microspheres were investigated with TEM, size analyzer, EDX and TG respectively. This core/shell microspheres as light scattering agents were blended with polymethyl methacylate（PMMA） resin to prepare light scattering material. When the concentration of core/shell microspheres SS6 was 1%(mass), the haze of PMMA sheet（2mm） was 88.16%,transmittance was 72.5%. When the concentration of SS6 was 2%(mass), the haze of PMMA sheet was 92.13%.

Effects of ammonia on microstructure and graphitic degree of carbon nanotubes prepared by CVD method

MI Wanliang;LIN Y.S.;LI Yongdan;ZHANG Baoquan

2006, 57(4): 964-969.

Abstract ( 603 )

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Vertically aligned carbon nanotubes (CNTs) was prepared on porous Al₂O₃ substrate by the CVD method with ferrocene as catalyst precursor, acetylene as carbon source and NH₃, N₂as carrier gases. Raman spectrum, scanning electron microscope (SEM), high-resolution electron microscope (HRTEM),X-ray diffraction (XRD) and elemental analysis were employed to characterize the materials.Experiment results showed that CNTs grown in NH₃ were bamboo-shaped structure at 800℃, containing about 3.46%(mass) N element and had a space between graphitic layers about 0.384 nm. Moreover, Fe₃C and Fe₂N or Fe₃N compound were detected in the carbon product.Catalyst surface property changed as a result of the NH₃ adsorption in Fe catalyst and adulteration of N in the CNTs made the CNTs show some crystal distortion and a low graphitic degree. CNTs diameter increased with reaction temperature.

Stability of gold nanoparticles modified with DNA

YANG Wei;LI Wei;ZHANG Jinli

2006, 57(4): 970-974.

Abstract ( 644 )

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Gold nanoparticles show promising applications in the field of molecular biology and R&D of biological sensors. Aiming at overcoming the irreversible aggregation of nano-gold in electrolyte solutions, this work investigated the effect of DNA modification on nano-gold stability in the presence of sodium ions, through the characterization of UV, TEM and Zeta potential measurements. It was indicated that the Zeta potential of nano-gold depended on the diameter of particles. Nano-gold particles with diameter of 13 nm were stable at the Zeta potential of -44.4 mV, while irreversible aggregation of particles appeared quickly when a sodium buffer was added to the solution. UV spectra of kinetic properties for the DNA modified nano-gold particles reflected the high stability of the system with the addition of sodium ions.

Self-consistent theory of bidisperse polymers grafted to surface

SUN Zhe;SONG Haihua

2006, 57(4): 975-980.

Abstract ( 620 )

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A self-consistent field theory (SCFT) for polydisperse polymers grafted to a surface was developed. By solving the resulting equations numerically, both density profiles and free end distributions for bidisperse polymers consisting of two different chain lengths were simulated with moderate to strong excluded volume interactions. The results showed that the monolayer of bidisperse polymers separated into two sublayers as excluded volume interactions increased. The density profiles simulated by the self-consistent field theory were consistent with the results of the strong stretching theory when excluded-volume interactions were high. Also the free end distributions of long chains were close to the prediction of strong-stretching theory(SST)in that case. But the free end distributions of short chains deviated from the SST results evidently. The average trajectories for both short and long chains were calculated. It revealed that short chains in bidisperse polymers were less stretching than the monodisperse chains with the same chain length. However long chains in bidisperse polymers were more stretching than the monodisperse chains with the same chain length in the inner layer and less stretching than that in the outer layer.

Kinetics of thermal degradation of special engineering thermoplastics PPESK and PPES and life estimation

HE Wei;LIAO Gongxiong;JIN Qifeng;FENG Xuebin;JIAN Xigao

2006, 57(4): 981-986.

Abstract ( 691 )

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New special engineering thermoplastics poly (phthalazinone ether sulfone) (PPES) and poly (phthalazinone ether sulfone ketone) ［PPESK(1/1)］ containing phthalazinone were synthesized by step-polymerization. The kinetics of thermal degradation of PPES and PPESK(1/1) in nitrogen were studied at several heating rates by thermogravimetry analysis (TGA). According to the Satava method, the thermal degradation mechanism of PPESK(1/1) was randomly nucleating and nucleus growth, and the order of reaction n=1.The thermal degradation mechanism of PPES, however, was phase boundary controlled reaction and the order of reaction n=2.The kinetic parameters, including the energy of activation and frequency factor of degradation reaction for PPES and PPESK(1/1) were analyzed by the Friedman, Kissinger-Akahira-Sunose(KAS) and Ozawa methods. The aim of this work was to study the effects of heating rate and the ratio of ketone/sulfone on thermal degradation and life estimation. On the basis of kinetic parameters, the lifetime for high temperature was calculated and the ‘Kinetic Compensation Effects’(KCE) in the thermal degradation process was analyzed.

Preparations of zeolite ZSM-35 zembranes on porous α-Al₂O₃ tubes

ZHU Gang;WANG Jinqu;LU Jinming;YIN Dehong;BAO Zhongying

2006, 57(4): 987-991.

Abstract ( 583 )

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Respectively in the systems of pyrrodine and 1-Butylamine as templates, ZSM-35 type zeolite membranes were hydrothermally synthesized originally in situ on the outer surface of porous α-Al₂O₃ tubes with pore size of 3—5μm.Characterization of the as-prepared membranes with XRD and SEM showed that the prepared membranes were typical zeolite ZSM-35 membranes, on which the zeolite crystals grew interlockedly and compactly and covered completely the outer surface of the ceramic tubes with thickness of about 12—18 μm, and that templates with different structures influenced apparently the morphology of the as-prepared membranes; calcinations of as-synthesized membranes at different temperatures indicated the orientation of crystals on the as-prepared membranes tended to be along (h 0 0) direction with increasing calcination temperatures; and at ambient temperature，H₂, N₂ and C₃H₈ single component permeance tests of the membranes reached the order of magitude 10^-6 with H₂/N₂ and H₂/C₃H₈ selectivity factors respectively above their corresponding ideal Knudsen diffusion factors.

Lactonization and condensation polymerization of 5-hydroxylevulinic acid

ZHANG Yan; WU Linbo;LI Feng;LI Bogeng

2006, 57(4): 992-996.

Abstract ( 872 )

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5-Hydroxylevulinic acid (5-HLA) was synthesized via modified bromination and hydrolysis using levulinic acid (LA) as starting material. Based on the hydroxyl and the carboxyl groups of the 5-HLA, poly(5-hydroxylevulinic acid), a novel aliphatic polyester, was synthesized by direct polycondensation using SnCl₂•2H₂O as catalyst. In addition, 1,6,9,13-tetraoxadispiro ［4.2.4.2］tetradecane-2,10-dione (or altaicadispirolactone), a dimer of the 5-HLA, was synthesized by cyclolactonization catalyzed by BF₃•OEt₂. Altaicadispirolactone is one of the chemical components of Anemone altaica C.A.May, a traditional Chinese medicinal material. Structures of the dimer and the polymer were characterized with GC-MS,¹H NMR, FT-IR, element analysis and GPC, respectively. Two plausible mechanisms for the cyclolactonization reaction were presented.

Preparation of blend fixed carrier membranes containing polyvinylamine and its CO₂/CH₄separation performance

YI Chunhai; WANG Zhi;ZHANG Lili;HU Jinkang;WANG Jixiao;WANG Shichang

2006, 57(4): 997-100.

Abstract ( 648 )

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Polyvinylamine(PVAm)/polyethylene glycol(PEG) and PVAm/Poly(N-vinyl-γ-sodium aminobutyrate)(PVSA) polymer blends were prepared in this study. Composite membranes for the facilitated transport of CO₂ were prepared by using the dip-coating process with polymer blends as separation layer and polyethersulfone ultrafiltration membrane as substrate.The effects of blending composition on the structure and performance of the membranes were investigated by testing the crystallinity and gas permselectivity of membrane. The results showed that the proper blending of PVAm with PEG could reduce the membrane crystallinity and increase the effective permeation area and carrier content.The membrane with 10%(mass)PEG has the highest pure CO₂ permeation rate of 4.2×10^-9cm³(STP)•cm^-2•s^-1•Pa^-1 and highest CO₂/CH₄ ideal selectivity of 63.1 at 25℃ and 122.7 kPa of feed pressure. As for the PVAm/PVSA blend membrane, a proper blending composition could also improve the permselectivity of membrane. The membrane with 33%(mass) PVSA showed the highest CO₂/CH₄ ideal selectivity, while the membrane with 50%(mass) PVSA possessed the highest CO₂ permeation rate.

Modeling and control of ceramic membrane thickness during dip-coating process

DING Xiaobin;FAN Yiqun;XU Nanping

2006, 57(4): 1003-1008.

Abstract ( 743 )

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α-Al₂O₃ membrane supported on α-Al₂O₃ porous substrate was formed by dip-coating and the formation process of the top layer was investigated based on experiments and theories of capillary filtration and film-coating. A model was developed to interpret quantitatively the formation process of the top layers on the porous substrate and all variables affecting top layer thickness were considered in the model.The results of theoretical analysis showed that the effects of six variables,namely the mass concentration of ceramic powder(W_s), the viscosity of suspension (η), the diameter of ceramic powder(r), the pure water permeability of support(Q),dipping time(t) and the withdrawal speed of the support(U),on the thickness of the top layer were highly significant. In order to validate the model developed,ZrO₂ membranes were prepared by dip-coating using the slurry with different mass concentrations of ZrO₂ powder. The experimental data of the thickness of the as-prepared ZrO₂ membranes showed good agreement with the model.

Synthesis, characterization and photoconductivity of azo-porphyrins

LIU Xingang;FENG Yaqing;LI Xianggao;XIE Xiaolei

2006, 57(4): 1009-1013.

Abstract ( 669 )

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Two azo-porphyrins were synthesized by aromatic nitro-group reduction, diazotization and coupled reaction from tetra(nitrophenyl)porphyrin. They were characterized with ¹H NMR, MS, IR and UV-visible spectra.Dual layer devices were prepared by using the azo-porphyrins as charge-generation layer separately, and their photoconductivities were measured and discussed. The experimental results showed that the photoconductivities of azo-porphyrins were improved compared to tetraphenylporphyrin (TPP). Their sensitivities are 1.8 and 28.8 lx•s respectively.

Crystal structure of casting polypropylene

YIN Bo;YANG Mingbo

2006, 57(4): 1014-1018.

Abstract ( 816 )

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The crystal structures of several casting polypropylenes were characterized with differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The effects of temperature, draw ratio and cooling rate on crystal structure were discussed. The main conclusions were listed as follows: drawing could increase the crystallinity of casting polypropylene, but could not induce the formation of the γ-form.Temperature and cooling rate could affect the formation of the γ-form.The slower the cooling rate, the more easily the γ-form developed; γ-form was found in the samples crystallized at 95 and 115℃ and the γ-form content of the sample at 115℃ was higher than that at 95℃.

In-situ synthesis of b-oriented silicalite-1 membrane on chitosan-modified silica-zirconia intermediate layer

LIU Xiufeng;LANG Lin;ZHANG Baoquan;LIN Y. S.

2006, 57(4): 1019-1022.

Abstract ( 712 )

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The b-oriented silicalite-1 membrane on the substrate α-Al₂O₃ pre-coated with a silica-zirconia intermediate layer was synthesized by using in-situ crystallization. The influence of chemical properties of the substrate surface on crystal growth and orientation was investigated. The result indicated that the surface modification by pre-coating a thin film of chitosan was conducive to the formation of b-oriented silicalite-1 membrane with good quality.

Process of dispersion copolymerization of styrene and acrylonitrile in polyether

LV Shijun;GUO Ruiwei

2006, 57(4): 1023-1026.

Abstract ( 673 )

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The dispersion copolymerization process of styrene (St) and acrylonitrile (AN) in polyether was studied by dynamic light scattering，liquid chromatography and UV. The results showed that in the process，in appropriate polymerization condition, the nucleation mechanism was dominated by the agglomeration nucleation of graft polymers, and then the stable dispersion system could be prepared.After the nucleation period,the number of particles kept constant and particles swelled by the action of monomers and grew by the polymerization of monomers in the dispersed phase and kept stable by adsorbing graft polymers formed in the continuous phase.