CIESC Journal

Thermodynamic properties of binary system of 0.716 H₂O+0.284 n-C₄H₉OH

NAN Zhaodong;DENG Yingxia;XUE Xia;TAN Zhicheng

2006, 57(2): 237-240.

Abstract ( 584 )

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The molar heat capacity values of the binary system composed of 0.716 molar fraction H₂O+0.284 molar fraction n-C₄H₉OH were measured by an adiabatic calorimeter in the temperature range from 78 K to 320 K.The functional relationships of heat capacity with respect to thermodynamic temperature were established.Glass-transition occurred at(111.9±1.2)K.The phase transitions took place at (179.26±0.77)K and (269.69±0.14)K corresponding to the solid-liquid phase transitions of n-butanol and water, respectively. The phase-transition enthalpy and entropy of water were calculated. The thermodynamic functions of the binary systems relative to 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.

Entropy generation analysis and performance evaluation of heat transfer enhancement through internal flow

XIE Gongnan;WANG Qiuwang;LUO Laiqin

2006, 57(2): 241-245.

Abstract ( 718 )

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An analytical method based on the entropy generation theorem for fluid flow and heat transfer process was developed with the assumption of fully developed flow and constant wall temperature,and the method was used to obtain dimensionless entropy generation number, and performance evaluation criteria (PEC) of heat transfer enhancement were obtained with the constraints of identical mass flow, pump power and pressure drop respectively under fixed heat duty. The applications of these treatments were illustrated by the analysis of heat transfer and fluid friction characteristics of internally finned tubes from literature data.It was shown that the dimensionless entropy generation number depended exclusively on Reynolds number and wall-to-inlet temperature difference for a given duct or tube, and the method might help to identify inappropriate enhanced tubes or extended surfaces and assist engineers to design better heat transfer equipment with the criteria assessing the merits of augmentation techniques in connection with energy conservation and exergy destruction according to entropy generation analysis.

Intensity analysis of natural convection in fluid layer with phase change material particles

DAI Chuanshan;ZHANG Yongfa;SUN Pingle

2006, 57(2): 246-250.

Abstract ( 612 )

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The intensity of Rayliegh-Bénard convection in a fluid layer dispersed with phase-change-material particles was studied. Instead of using the conventional mean temperature method, two new methods were proposed for evaluating the intensity of convection in a horizontal fluid layer with strongly variable apparent specific heat. One method was by introducing a modified Ste number in a Nu-Ra correlation or using the integrally averaged specific heat over the layer in calculating the Rayliegh number. The other method was by using the supercriticality (Ra/Ra_c) as the intensity parameter. The critical Rayliegh number Rac could be calculated with the linear stability theory. After giving two kinds of correlating functions of non-dimensionalized apparent specific heat functions with respect to temperature, the influences of their amplitudes and phase angles on the critical Rayliegh number were investigated. Results showed that the two proposed methods were more rational comparing with the convectional method. The optimum convective mode predicted by the two methods was in agreement with previous experimental results.

Boiling heat transfer of R123 outside single horizontal doubly-enhanced tubes

LIU Qibin;HE Yaling;ZHANG Dingcai;TAO Wenquan

2006, 57(2): 251-257.

Abstract ( 627 )

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An experimental study on the performance of boiling heat transfer of R123 outside a single horizontal tube was conducted with three doubly-enhanced tubes (No.1，No.2 and No.3)with different geometries at saturation temperatures of 12℃and 10℃ respectively. Tube No.1 was Turbo-B type of Wolverine, and tube No.2,3 also belonged to this type with a minor difference in the tip of the fin. Wilson plot technique was used to separate the boiling heat transfer resistance from the total thermal resistance. It was found that under the same conditions, the in-tube convective heat transfer coefficients of the doubly-enhanced tubes were 2.8—3.1 times of that of the smooth one, and the boiling heat transfer coefficients of R123 were generally lower than those of R22. The thermal resistance analysis reveals that the thermal resistances of the water side and refrigerant side were of the same order for most of the tubes.With the increase in heating water velocity, the thermal resistance of the inner water decreased and that of the refrigerant increased. To further enhance heat transfer, the augmentation of the inner side and the outer side was equally important.

New TPD model for activation energy estimation

LI Xiang;LI Zhong;LUO Ling’ai

2006, 57(2): 258-262.

Abstract ( 647 )

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A new nonlinear temperature programmed desorption(TPD)model was proposed. This model was different from the classical TPD model in that the re-adsorption phenomenon of the adsorbate was taken into account. TPD experiments were carried out to determinate the TPD spectra of dibenzofuran desorbed from the Norit RB1, Monolith and Chemviron activated carbons. Based on these experimental spectra the activation energy of dibenzofuran desorption on the three activated carbons was estimated by using the classical TPD model and the new nonlinear TPD model. The results showed that the activation energy calculated by the classical TPD was 8％—12％ higher than that calculated by the nonlinear TPD model, indicating the remarkable effect of the re-adsorption phenomenon on desorption activated energy.

Numerical study of fluid flow and heat transfer over fin-and-flat tube bank heat exchanger with vortex generators

SHI Baizhan;SUN Dongliang;WANG Liangbi

2006, 57(2): 263-268.

Abstract ( 648 )

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The entry laminar flow and heat transfer over the fin-and-flat tube bank heat exchanger with vortex generators was investigated with numerical analysis in the Reynolds number range of 300—1800. A set of laminar flow predictions were presented to demonstrate the effects of the staggered ratio(Sr) on the local Nusselt number(Nu_local) and the span-averaged Nusselt number(Nu_b). The correctness of the numerical analysis method was validated by the experimental data and the numerical analysis method could be used to research and develop the heat exchanger with vortex generators.

Transient thermal effect on electroosmotic flow in mini-tube

DU Xiaoze;ZHAO Tianshou;YANG Lijun

2006, 57(2): 269-273.

Abstract ( 611 )

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A mathematical model was developed to investigate the effect of transient thermal effect on capillary electroosmotic flow. The model consisted of the Poisson-Boltzmann equation, the Navier-Stokes equation, and the energy equation coupled through temperature. Transient developments of the velocity and temperature profiles were obtained. Since the change in the velocity profile with time was mainly caused by the temperature change, the evolutions of the velocity profiles and temperature profiles always synchronized with each other.The developments of temperature profile, as well as velocity profile due to thermal effects were obtained and discussed under different cooling conditions and different electric field strengths. The present model enabled the determination of a suitable cooling condition at the outer surface of the capillary tube to avoid overheating and provided an adequate migration velocity for given dimensionless numbers, which characterized thermal hydraulic fluid flow due to electrokinetic effects.

Application of chaotic recurrence analysis for identification of oil/water two-phase flow patterns

JIN Ningde;CHEN Wanpeng

2006, 57(2): 274-280.

Abstract ( 791 )

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The method of using the time series data generated by the Lorenz equation to verify the validity and sensitivity of recurrence quantification analysis was presented,and this method was used to identify oil/water two-phase flow patterns. The research indicated both dispersed points texture and line type texture appeared on recurrence plot for the transitional oil/water two phase flow pattern; however, only line type texture appeared on recurrence plot for the oil-in-water flow pattern. This phenomenon showed that the texture on recurrence plot was sensitive to the change of oil/water two-phase flow pattern, and the recurrence quantification analysis was a valid supplementary diagnosis tool for flow pattern identification.

Comparison of dynamic behavior between hard-sphere and soft-sphere simulation in gas-solid fluidized beds

WANG Fang;OUYANG Jie;ZHANG Xiaohua

2006, 57(2): 281-287.

Abstract ( 744 )

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In order to compare the difference between the hard-sphere method and soft-sphere method, the dynamic behavior in gas-solid fluidized beds was simulated by the hard-sphere method and soft-sphere method in which particle diameters were unequal. Particle average velocities with increasing time and particle trajectories were compared. At the same time, the dynamic behavior in fluidized beds and the distribution of particle average velocity were also studied when restitution coefficients were different. Simulation results indicated that restitution coefficients of the hard-sphere method and soft-sphere method had distinct influence on particle average velocities. The bubbling phenomena could be simulated by the hard-sphere method when restitution coefficients were smaller, while such phenomena could be simulated by the soft-sphere method when restitution coefficients were larger.The larger restitution coefficients, the larger the change of particle average velocities in the hard-sphere method, but the smaller the change of particle average velocities in the soft-sphere method. Moreover, the CPU time in the hard-sphere method was much larger than that of the soft-sphere method due to the different ways in dealing with the collisions and the different time steps of particle collisions.

Experimental research and numerical simulation of asymmetric impinging streams

XU Jianliang;LI Weifeng;CAO Xiankui;DAI Zhenghua;LIU Haifeng;WANG Fuchen;GONG Xin;YU Zunhong

2006, 57(2): 288-291.

Abstract ( 705 )

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The characteristics of asymmetric impinging streams were measured with hot wire anemometry and simulated with CFD. The results of numerical simulation were consistent with the results of experiments. The characteristics of axial velocity of asymmetric impinge streams were similar with those of free round jet except in the vicinity of the impinging face. When the distance of two nozzles was fixed, the offset of impinging stagnation point on the axis increased with the ratio of velocity and the nozzle diameter. When the ratio of velocity was fixed, the offset of impinging stagnation point on the axis increased with the distance of two nozzles.

Dynamics of behavior of fine particulate matter in pulverized coal combustion

GENG Jun;LIU Zhaohui;ZHANG Fenghao;ZHENG Chuguang

2006, 57(2): 292-299.

Abstract ( 792 )

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Based on the concept of the moment method, the poly-dispersed particulate matter (PM) generated during pulverized coal combustion was partitioned into fine-mode and coarse-mode. A set of computation models for describing the behavior of particle size distribution (PSD) evolution was then developed, which considered the effects of the Brownian coagulation of fine-mode, the heterogeneous condensation on the surface of coarse-mode.The influence of capture of fine-mode particles on the surface of coarse-mode particles was specially investigated.The models were then used to make prediction and analysis of the PSD evolution of fine PM in typical coal combustion environment.

Direct numerical simulation of particle behavior in homogeneous isotropic turbulence

HE Zhu;LIU Zhaohui;CHEN Sheng;WENG Lei; ZHENG Chuguang

2006, 57(2): 300-305.

Abstract ( 625 )

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Direct numerical simulations were conducted to investigate the behavior of heavy particles in homogeneous isotropic turbulence. The present study focused on the effect of particle inertia on the autocorrelations of the particle velocity and the fluid velocity seen by particles and the dispersion characteristics of particles. The Lagrangian integral time scale of particles monotonically increased as the magnitude of the particle response time increased, while that of the fluid seen by particles remained relatively constant.It reached maximum when the particle response time was close to the Kolmogorov time scale of the flow. Particle dispersion increased as the particle inertia increased for small particles;while for larger particles, it decreased as particle inertia increased.Particle eddy diffusion coefficient was maximal and greater than that of the fluid by about 30% when the preferential concentration was most obvious. The concentration field of the particles with τ_p/τ_k≈1.0 showed that particles tended to be collected in regions of low vorticity (high strain) due to preferential concentration.

Selective catalytic reduction of nitrogen oxides by methane over Ni/H-USY catalysts

ZHANG Hui;FANG Heliang;SHI Yao; LI Wei;TAN Tian’en;ZHENG Xiaoming

2006, 57(2): 306-310.

Abstract ( 525 )

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Selective catalytic reduction(SCR) of NOx by CH4 over Ni/H-USY of different Ni loading and trace Pd and Pt elements used to improve the activity of a Ni/H-USY catalyst in the excess of 5% oxygen was investigated. Compared with Ni/H-USY, the Ni-Pd/H-USY and Ni-Pt/H-USY catalysts showed higher activity in a wide range of reactive temperature. A synergistic effect between Ni/H-USY and Pd element or Pt element enhanced the conversion of NO_x. Samples of the catalysts were characterized with TPR, X-ray diffraction (XRD).The addition of Pd might be responsible for the higher activity because it can produce a highly dispersed active surface area as bound-state Ni species.

Synthesis of TiO₂ nanowires array film catalyst and kinetics of photocatalytic degradation of formaldehyde in gas phase

ZOU Lixia;ZHONG Qin;LIU Qingcheng

2006, 57(2): 311-317.

Abstract ( 578 )

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The photocatalysts of TiO₂ nanowires array film（TiO₂/AAO）and TiO₂/glass film，TiO₂/fiberglass cloth film were prepared by sol-gel chemistry and were characterized with XRD，electron probe microanalysis(EPMA) and specific surface area measurement. The photocatalytic activity for degradation of gaseous formaldehyde at different initial concentration were also studied and compared.The results showed that the TiO₂ nanowires was uniform, about 26 nm in diameter and 1.2 μm in length. The TiO₂/AAO photocatalyst with smaller density and high specific surface area had the greatest reaction rate constant k and Langmuir adsorption constant K,and more adsorption active sites for gaseous formaldehyde at low concentration under UV light as compared with other supports.The high specific surface area photocatalyst played a bigger role in enriching gas and was more beneficial in enhancing photodegradation efficiency for low concentration gas.

Kinetics of bamboo pyrolysis

ZENG Kaibin;JIANG Binbo;CHEN Jizhong

2006, 57(2): 318-323.

Abstract ( 624 )

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Bamboo materials were pyrolyzed in TGA equipment (TGA/SDTA851^e) at heating rate of 5,10,20,30 K•min^-1 in the temperature range of 313～650 K and N2 atmosphere.The pyrolysis process of bamboo consisted of three steps: pre-pyrolysis of water evaporation，first step pyrolysis and second step pyrolysis. The kinetics of bamboo pyrolysis was analyzed based on the Levenberg-Marquardt method. The first step of bamboo pyrolysis could be considered as the pyrolysis of semi-cellulose to volatile matter only and well described by a first-order reaction model.The second step of bamboo pyrolysis could be considered as the pyrolysis of cellulose and lignin to volatile matter and char,and well described by a parallel first-order reaction model.The first step of bamboo pyrolysis was dependent on heat-up rate,while the second step of bamboo pyrolysis was independent of heat-up rate.

Effect of space velocity in syngas reduction on performance of Fe/Cu/K/SiO₂ catalyst for slurry phase Fischer-Tropsch synthesis

HAO Qinglan;BAI Liang;XIANG Hongwei;LI Yongwang;YI Fan;XU Binfu

2006, 57(2): 324-330.

Abstract ( 767 )

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The effects of space velocity in syngas reduction on the reaction performance of the Fischer-Tropsch synthesis (FTS)over a spray-dried spherical Fe/Cu/K/SiO₂ catalyst and on the bulk compositions of the reduced and used catalysts were investigated in a continuous stirred slurry reactor under reaction conditions of 250—280 ℃, 1.5 MPa, H₂/CO=0.67 and 2.0 L•（g cat）^-1•h^-1. The results showed that the BET surface area of the reduced catalysts decreased with the increase of the space velocity in reduction, and the reverse trend for the average pore diameter was observed. The space velocity in syngas reduction did affect the reduction process. The catalyst was easier to be reduced at a higher space velocity. The higher partial pressure of CO₂ in slurry reactor during reduction could partially oxidize the iron carbide. And the content of Fe³⁺⁽spm) was higher in the reduced catalyst. The space velocity in syngas reduction had no obvious effect on the hydrocarbon selectivity, and the effect of the space velocity in syngas reduction on the catalyst activity and stability was significant. The deactivation rate of the catalyst was higher at both lower and higher space velocity. The appropriate space velocity in syngas reduction was 1.0—2.0 L•（g cat）^-1•h^-1.

Isolation of desacetyl cephalosporin C by activated carbon

YU Haijun; CHEN Ligong;ZHAO Zijian;DONG Rongmei; TAN Qingzhong

2006, 57(2): 331-335.

Abstract ( 726 )

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The effective separation of desacetyl cephalosporin C(DCPC) from cephalosporin C(CPC) and other impurities was achieved by using the powdery activated carbon as an adsorbent to deal with the waste drainage from the current process for CPC production.By eluting the carbon cake with ethanol-water system or isopropanol-water system, a DCPC solution of 80% purity was obtained. The yield for ethanol-water system was 75%, and that for isopropanol-water system could reach 80%.The experiments showed that separation was not good by eluting the adsorbent with 15% ethanol solution or 15% isopropanol solution, and 10% ethanol solution or 10% isopropanol solution was weak in elution.The good results of elution and separation were obtained by using 12%—13% ethanol solution or 12%—13% isopropanol solution;furthermore, 13% isopropanol solution had a better effect than 13% ethanol solution.

Membrane separation of paper-making black liquor pollutants

HUANG Jiangli;XU Nong;SHI Hanchang;QIAN Yi

2006, 57(2): 336-339.

Abstract ( 609 )

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Micro-membranes with pore size of 0.2 μm，0.5 μm and 0.8 μm were used to treat the black liquor of paper-making under the following experimental conditions:cross flow velocity 5 m•s^-1,operation pressure 0.3 MPa and operation temperature 20℃.The separation of pollutants with inorganic membrane and the membrane cleaning method were investigated.Membrane separation used for black liquor recycling in the paper-making process was studied.

Effect of rotary intensity on enhancement performance of rotary tubular microfiltration membrane separators

ZHOU Xiantao; PAN Jiazhen;CHEN Wenmei;CHU Liangyin;LI Bixian;CHEN Liqing

2006, 57(2): 340-346.

Abstract ( 674 )

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Based on analyzing the characteristics of high shear ratio, centrifugal pressure difference and mass transfer mechanisms in rotary tubular microfiltration membrane separators, the factors affecting the permeation ability were summarized into three essential factors: the structure permeation factor which increased with time and reflected the role of both membrane structure and irreversible membrane fouling, the reversible membrane fouling factor when the membrane tube was in stationary, and the enhancement factor produced by the rotation of the membrane tube. A relative enhancement factor which was the ratio by taking the permeation ability when the membrane tube was in stationary as a scale to measure the permeation ability in rotation was proposed to denote the degree of enhancement produced by the rotation of membrane tube. The relationship of the relative enhancement factor with the rotary Taylor number in different concentrations, different pressures and different mass transfer controlling mechanisms were investigated by experiment, and then the causes of its characteristics were analyzed.

Preparation of macro-porous pellicular agarose-glass composite matrix and its application to protein adsorption

ZHOU Xin;SUN Yan;LIU Zheng

2006, 57(2): 347-352.

Abstract ( 687 )

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A macro-porous pellicular agarose-glass composite matrix（MPAG）was prepared by coating 6% agarose gel onto glass beads by water-in-oil emulsification using a mixture of cyclohexane and fine calcium carbonate powder as porogenic diluents. The density of MPAG was 1.7 g•ml^-1 and the average bead size was 127.8 μm. MPAG was derivatized with diethylaminoethyl(DEAE) and subjected to the adsorption of bovine serum albumin. Compared to macro-porous matrix or homogeneous matrix derivatized with DEAE, DEAD-MPAG gave a higher adsorption capacity at a faster mass transfer rate.

Selective concentration of PUFAs in glyceride from fish oil with immobilized lipase

ZHENG Yi;ZHENG Nan;WU Songgang

2006, 57(2): 353-358.

Abstract ( 674 )

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ω-3 Polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have some pharmacological and physiological effects on human health. They are mainly from fish oil. The present study was made to enrich PUFAs in glyceride from fish oil by the selective hydrolysis of immobilized lipase. The method of combining adsorption with crosslinking was used for Aspergillus oryzae lipase immobilization. Lipase was immobilized by adsorption onto diatomite at 25℃ for 6 h and then crosslinked with 0.5% glutaraldehyde for 1.5 h. The effects of hydrolysis of fish oil with this immobilized lipase were studied.The optimal temperature was 38℃,optimal rotating speed was 200 r•min^-1, the optimal ratio of oil to water was 1∶1, the optimal amount of lipase was 150 U•(g oil)^-1, and the optimum time for concentrating PUFAs in glyceride was 24 h. The results showed that under this hydrolysis conditions the contents of EPA, DHA and EPA+DHA in glyceride were increased respectively from 3.0% to 7.0% , from 4.3% to 14.5% and from 7.3% to 21.5%.

Dechlorination of dichlorophenol in waste water by immobilized laccase

ZHANG Shujiang;GAO Enli;XIA Liming

2006, 57(2): 359-362.

Abstract ( 825 )

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Laccase from Coriolus versicolor was immobilized by adsorbing first on activated carbon, and then entrapping into calcium alginate gels. 2,4-Dichlorophenol in wastewater was dechlorinated by the immobilized laccase in a columnar reactor. The optimal temperature and pH for the reaction were 40℃ and 4.5, respectively. Compared with free laccase, the immobilized laccase had better thermostability, and also had a broader active range of pH and temperature. The decholorination efficiency of laccase on 2,4-dichlorophenol (1 mmol•L^-1) was all above 99.5% with 0.5 mmol•L^-1 chloride ions released into the water during 8 repeated batch reactions. The results showed good prospect of application in the biochemical treatment of polluted wastewater.

Preparation of clarithromycin-containing floating pellets in stomach

ZHENG Jianhua;BAO Decai;LIU Chaowu; ZHAO Yanjun;MA Xiaojun

2006, 57(2): 363-366.

Abstract ( 798 )

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Two types of floating pellets in stomach were prepared. The first one： floating alginate pellets containing ethylcellulose and clarithromycin (AE)were pellets with dispersed ethylcellulose in the alginate gel matrix. The second one：ethylcellulose microspheres containing clarithromycin (Em) were first prepared by the emulsion solvent diffusion method, and then alginate pellets containing ethylcellulose microspheres (AEm) were prepared. The effects of processing parameters on morphology, size distribution, drug loading, in vitro drug release profiles, in vitro floating property of pellets were investigated. The results showed that about 80% of drug incorporated in AE was released at 2 h, while AEm with moderate drug content had sustained drug release property. The accumulative drug-release percent of AEm in vitro at 6 h were 65.9%—78.8%, and AEm could float in acetate buffer solution for more than 8 h.

Bio-oxidation and metabolism of phenols and anilines

YAO Risheng;SUN Min;WANG Lei;DENG Shengsong

2006, 57(2): 367-370.

Abstract ( 655 )

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This paper reports on the degradation of phenols and anilines using hydrogen peroxide as oxidizer and enzyme from Serratia marcescens Y-SM01 as catalyst. First, the COD_Cr values before and after degradation were measured. Then, changes of molecular structures during the process were investigated with UV-VIS, IR and HPLC. It was found that after degradation, for some compounds such as hydroquinone, peaks on UV-VIS and IR spectra which belong to phenyl ring all disappeared, and HPLC found small molecules such as organic compounds. So the mechanism was clarified that in the degradation the phenyl ring was cleaved and small molecules were introduced, which just caused the COD_Cr values of degradable compounds such as hydroquinone to decline greatly. Also, the connection between degradation properties and structures of phenols and anilines was analyzed, and the conclusion was as follows: di-/tri-phenols/anilines were easier to degrade than mono-phenols/anilines; ortho-/para- substituted compounds were easier to degrade than meta- substituted compounds; electron-attracting substituents such as —OH, —NH₂, —OCH₃ made degradation easier, while electron-withdrawing substituents such as —NO₂, —Cl, —COOH made degradation more difficult.

Transient variations of bed voidage and particle size distribution in expanded bed during yeast suspension loading

ZHOU Xiaoping;SHI Qinghong;YANG Zheng;SUN Yan

2006, 57(2): 371-375.

Abstract ( 881 )

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Upon the application of 3%yeast suspension as a feedstock to an expanded bed of Streamline AC equilibrated with 0.02 mol•L^-1 phosphate buffer (pH 7.0), the transient variations of local bed voidage and particle size distribution were investigated. The experiments were carried out in a customized glass column (26 mm I.D.) modified by side ports. It was exhibited that the introduction of unclarified feedstock with a high viscosity and density induced the upward movement of particle and consequently a change in local bed voidage and particle size distribution. At a given bed height, voidage firstly decreased to a minimum and then increased to a high equilibrated value in voidage. The transient process not only included a fluctuation in particle size distribution but also involved the change in particle concentration at a certain bed height, particularly at the middle and top of the column.

Extraction of dihydromyricetin by MDMCE

LI Wei;ZHENG Cheng;NING Zhengxiang

2006, 57(2): 376-379.

Abstract ( 597 )

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The process which microwave is applied to dynamic multi-stage countercurrent extraction,namely the process of microwave dynamic multi-stage countercurrent extraction (MDMCE),for extracting dihydromyricetin from Ampelopsis grossedentata was investigated.Comparison of MDMCE and microwave static batch extraction (MSBE) demonstrated that both the driving force of mass transfer and extraction efficiency of MDMCE were higher than those of MSBE.The optimum extraction conditions of 5 stages MDMCE obtained by orthogonal design were as follows：10 min extracting time for 5 stages MDMCE（2 min for every stage）, 110 ℃, 1∶30 material to solvent ratio, 600 W microwave power. Under these conditions the extraction yield of dihydromyricetin and percentage of dihydromyricetin in residue were 92.2 % and 3.1% respectively. A kinetic model of single vessel for MDMCE was developed and the functional relation between dihydromyricetin concentration and extraction time was ln(ΔC)=0.2985lnt-12.52.

Production process for ursolic acid

LI Kaiquan;CHEN Wu;LI Xiangyi

2006, 57(2): 380-381.

Abstract ( 608 )

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Production of ursolic acid, the anti-hepatitis effective composition from natural plant,Sambucus chinensis Lindl.was carried out and the scale-up preparation technology was studied.Extraction of the herb Sambucus chinensis Lindl.was extracted in reflux with 7 volume times of refluxing ethanol at 80℃ for 1 h for two times.The extract was purified with a selt-made specific impurity remover “YCXY-1” to yield ursolic acid of high purity.A new “Extraction/Gelation” technology for the production of ursolic acid was developed. The specific impurity remover “YCXY-1” showed high effectiveness in purification. The purity of the mass-produced ursolic acid was up to 99.8%. The chemical structure of the product was confirmed by the physicochemical constants and spectroscopic identification. The production of high-purity ursolic acid was optimized with natural plant as raw material and with only ethanol as extracting solvent. The difficulties such as isolation and impurity removal were addressed effectively. The novel technology is reasonable, convenient, practical, low-cost, high-yield, suitable for mass production.

Change of Saccharomyces cerevisiae in broth under high-pressure CO₂

WANG Yanji;YANG Wenshen; LIU Xiufeng; ZHANG Baoquan

2006, 57(2): 382-384.

Abstract ( 656 )

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Scanning electron microcopy (SEM) and differential scan calorimetry (DSC) were used to evaluate structure changes in Saccharomyces cerevisiae cells under the treatment of high-pressure CO₂ over the fermentation broth. Compared with controlled fermentation, the ethanol concentration in the fermentation broth after 24 h greatly decreased under high-pressure CO₂. DSC studies of whole cells showed that the ribosomes and DNA were not changed after high pressure CO₂ treatment although some components were denatured,leading to the lowering of the corresponding decomposition temperature. The fermentation under 1 and 8 MPa CO₂ caused obvious changes on the wall surface of cells.Wrinkles were formed on the wall of cells and the cell wall coarseness increased at elevated pressure as observed with SEM observations.

Effects of additives on preparation and use of calcium sorbent for SO₂ removal

ZHANG Hu;TONG Huiling;DONG Shanning;CHEN Changhe

2006, 57(2): 385-389.

Abstract ( 626 )

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Calcium sorbent was prepared with NaOH, Na₂CO₃, MgO as additives. A bench scale experiment was carried out to study the effects of additives on SO₂removal. The results showed that additives could enhance the sorbent’s reactivity with SO₂ by optimizing the structural properties of sorbent. SEM and EDAX analysis indicated that additives enlarged sorbent’s surface area and changed its chemical composition, which was beneficial to the desulfurization process.NaOH+Na₂CO₃ promoted sorbents showed better effects than those using NaOH alone.

Influencing factors and mechanism of decomposition of 4-nitrophenol by US/O₃

SHI Huixiang;XU Xianwen;WANG Dahui

2006, 57(2): 390-396.

Abstract ( 793 )

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The effects of gas flow rate, temperature, pH value, initial mass concentration of 4-nitrophenol solution, and ultrasonic intensity on the decomposition efficiency of 4-nitrophenol by ultrasonic irradiation and ozone were studied. The results showed that the decomposition efficiency of 4-nitrophenol increased with the increase of gas flow rate, ultrasonic intensity and pH values (pH≤6), and decreased with the increase of initial mass concentration of 4-nitrophenol solution, while both temperature and pH value (pH>6) were relatively not effective. The decomposition reactions of 4-nitrophenol by US/O₃, US and O₃ separately follow pseudo-first-order kinetics with rate constants 1.50×10^-3 s^-1，3.27×10^-5 s^-1 and 6.63×10^-4 s^-1 respectively, and the enhancement factor of 4-nitrophenol decomposition was around 216%. Ultrasound decomposed ozone,providing •OH augmentation,which was the main cause of synergetic effect. The main intermediates during the decomposition included catechol, o-benzoquinone, hydroquinone, p-benzoquinone, phenol, fumaric acid, maleic acid, oxalic acid and formic acid as measured by high-performance liquid chromatograph (HPLC), gas chromatograph coupled with mass spectrophotometer (GC-MS) and ion chromatograph (IC) techniques. The decomposition mechanism of 4-nitrophenol was also discussed.

Analysis of scaling on absorber wall of CFB-FGD system and its mechanism

ZHAO Xudong;XIANG Guangming;YAO Qiang;MA Chunyuan

2006, 57(2): 397-402.

Abstract ( 651 )

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An analysis of scaling on the inside wall of the Circulating Fluidised Beds Flue Gas Desulphurization (CFB-FGD) absorber and its mechanism was carried out. It was found that deposition and agglomeration mainly occurred in a circular high humidity area which was 4 to 5 meters above from the nozzles. Such factors affecting the deposition were studied, including system running conditions, tower makeup, nozzle size, in-tower flow and temperature profiles. The composition of the deposited materials was analysed. It was found that both the composition and the forming mechanism of scaling were far different from the wet FGD, and that scaling was caused mainly by wet ash which was easy to adhere to the wall, and secondly by CaCO₃ which reflected the important role of CO₂in the scaling process. Finally, approaches to prevent scaling were proposed.For example，a specially designed multi-piped venturi scrubber was installed in order to increase the vertical velocity of the particles.

Contact resistance between graphite/phenolic resin composite plate and carbon paper

LIU Zonghao; XU Li;WANG Yuxin

2006, 57(2): 403-408.

Abstract ( 505 )

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Graphite/phenolic resin (PF) composite bipolar plates used for polymer electrolyte membrane fuel cells (PEMFCs) were prepared by a compression molding process. The contact resistance between the composite plates and carbon paper were measured with a four-probe method. The influences of contacting pressure, PF content and compression molding parameters on the contact resistance were investigated.The results show that contacting pressure and PF content had a great influence on contact resistance. The contact resistance decreased with the increase of contacting pressure and increased with increasing PF content evidently. The compression pressure and temperature had a smaller influence on contact resistance compared with contacting pressure and PF content. The contact resistance increases slightly with increasing compression pressure. The compression time and temperature had no effect on contact resistance.

Effect of structure of polymer ligands on oxygen-binding properties of cobaltporphyrin complexes

SHENTU Baoqing; WU Jianyi;WENG Zhixue

2006, 57(2): 409-413.

Abstract ( 624 )

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Synthesis and characteristics of 4-vinylimdazole，1-methyl-4-vinylimdazole, and their copolymers with octyl methacrylate, and the oxygen-binding properties of cobaltporphyrin (CoP) complexes with vinylimdazole copolymers were studied. The molecular mass and vinylimidazole content of poly(octyl methacrylate-co-4-vinylimidazole) (PO4Im) and poly(octyl methacrylate-co-1-methyl-4-vinylimidazole) (POM4Im) were determined by GPC and elemental analysis, respectively. PO4Im or POM4Im and CoP in dichloromethane solution were mixed to complex the imidazolyl residue of copolymers with the fifth coordination site of CoP to get CoP complexes. CoP complex displayed a reversible change in the UV-visible absorption spectrum from the deoxy form to the oxygen-binding one with an isosbestic point, in response to the partial oxygen pressure of the atmosphere. The oxygen-binding equilibrium curves of CoP complexes obeyed Langmuir isotherm, to give the oxygen-binding affinity p₅₀.The oxygen-binding affinity of PO4Im-CoP complex was larger than that of POM4Im-CoP complex. It was assumed that hydrogen bond formed in PO4Im improved the oxygen-binding affinity of the CoP complex. The binding and dissociation rate constants of oxygen to and from CoP complexes were large, which indicates a very rapid oxygen-binding.

Melting and plasticizing process of vibration induce single-screw extruder(Ⅰ) Melting mechanism and melting rate

QU Jinping;ZENG Guangsheng;HE Hezhi;JIN Gang;CAO Xianwu

2006, 57(2): 414-423.

Abstract ( 616 )

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With the use of vibration field along the screw axial direction, the melting and plasticizing process of vibration induced single-screw extruder varied periodically and the change of polymer viscoelasticity was non-linear,which could not be described by the classical melting theory. The dynamic transparent barrel visualization experimental method and the static half-open barrel visualization experimental method were adopted to investigate the influence of vibration parameters on the melting and plasticizing process.Melting mechanism was analyzed, and the melting physical model was established. Mass balance equation, momentum balance equation, energy balance equation and constitutive equation of the melting process with vibration were presented. With the help of sophisticated mathematical deduction, equations of melting rate and thickness of melt film were obtained.Melting rate and thickness of melt film was related to vibration parameters and was time-dependent.Melting rate increased while thickness of melt film decreased by vibration.Calculation were in good agreement with the result of experiment.

Melting and plasticizing process of vibration induce single-screw extruder(Ⅱ) Effect of axial vibration on melting process

ZENG Guangsheng;QU Jinping;HE Hezhi;JIN Gang;CAO Xianwu

2006, 57(2): 424-428.

Abstract ( 606 )

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With the help of physical and analytical models of melting and plasticizing described in the first report, the melting length and the solid bed distribution expressions of vibration induced single-screw extruder were presented. Low-density polyethylene (LDPE) was used in the calculation, and some conclusions were obtained.Melting rate increased,while thickness of melt film and melting length decreased with the increase of vibration frequency and amplitude.However after vibration intensity reached a limit value,melting rate,thickness of melt film and melting length would remain unchanged. In the end, the half-open barrel visualization experiment was used to prove the validity of the conclusion.Calculations were in good agreement with the result of experiment.

Kinetics of gas phase propylene polymerization using spherical TiCl₄/MgCl₂ catalyst

HU Jijiang;FAN Hong;BU Zhiyang;LI Bogeng

2006, 57(2): 429-435.

Abstract ( 711 )

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The kinetics of gas phase propylene polymerization was studied at elevated pressures by using a spherical TiCl₄/MgCl₂ catalyst. The experiments were carried out in a semi-batch olefin polymerization reactor equipped with an on-line computer control system. Important kinetic data such as instantaneous reaction rate of monomer were obtained. The effects of polymerization conditions on reaction kinetics were systematically studied. The Flory-Huggins equation was used to estimate the monomer concentration in the polymer amorphous region. It was found that reaction rate had a linear relationship with monomer concentration. The time evolution of polymerization rate under all conditions followed the same pattern, with a fast decay in the early stage of polymerization and a relatively slow decay in the later stage. An nth decay model was developed to describe the dynamic changes of polymerization rate. Experimental data were used to estimate the model parameters. The decay order n was found to be 2.5 and the lumped propagation activation energy was estimated to be 77.1 kJ•mol^-1, which was similar to the value in the liquid phase reported by other researchers.The model described the experiments well.

Properties of and decoloration of orcein dye on epicholorohydrin-dimethylamine cationic polymer/bentonite nanocomposite adsorption material

LI Qian;YUE Qinyan;GAO Baoyu;LIU Lili

2006, 57(2): 436-441.

Abstract ( 880 )

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A new cationic polymer，epicholorohydrin-dimethylamine polymer（EPI-DMA）as intercalary reagent was used to prepare a series of cationic polymer/bentonite （EPI-DMA/Bt）nanocomposite adsorption material.It was shown by the characteristic analysis that the surface area and degree of aggregation of the modified bentonite greatly increased as compared with that of unmodified bentonite and ξ electric potential changed from negative to positive. The adsorption of reductive reddish R, disperse reddish S-R,and activated reddish violet K-2BP on the EPI-DMA/Bt were also studied. The results indicated that the decoloration of three orcein dyes on EPI-DMA/Bt were much better than on Na-Bentonites. The relationship between adsorptive capacity (q_e) and equilibrium concentration (C_e) fitted the isothermal adsorption equations of Langmuir and Freundlich. The adsorption dynamics followed the law of Langmuir equation.

Hybrid supercapacitor with nanosized α-MnO₂/activated carbon as electrodes

WANG Xingyan; WANG Xianyou; HOU Tianlan;LI Jun;HUANG Qinghua

2006, 57(2): 442-447.

Abstract ( 669 )

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The supercapacitor using nanosized α-MnO₂ and activated carbon as electrode materials was developed,and the synthesization of nanosized α-MnO₂ and the effect of the concentration of electrolyte on the performance were studied in detail. Three kinds of supercapacitors, MnO₂/KOH/MnO₂, AC/KOH/AC and MnO₂/KOH/AC, were prepared. Cyclic voltammetry (CV), galvanostatic charge-discharge and time constant technology were used to study the performance of the electrodes and the supercapacitors. The results showed that excellent performance of the electrods was found when the concentration of KOH solution was 7 mol•L^-1.Specific capacitance of α-MnO₂could reach a value of 237 F•g^-1.The super-capacitors with AC electrode as negative electrode and asymmetric configuration had better characteristics than the ones composed of two identical AC or MnO2 electrodes. The operating voltage of α-MnO₂/KOH/AC hybrid super-capacitor was 1.5 V and had low self-discharge rate.

Interaction among process parameters in injection molding

ZHANG Zhilian;JIANG Bo

2006, 57(2): 448-452.

Abstract ( 686 )

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Based on filling/post filling simulation in injection molding and design of experiment (DOE) technology, the fractional factorial design method was introduced to investigate the significance of interaction among process parameters, and each factor’s effect on the quality of mold part was also studied. The results showed that the interaction was significant and cannot be neglected.

Phase inversion and properties of cationic water-borne polyurethane

SUN Xinbo;WANG Dening;YUAN Qiaolong

2006, 57(2): 453-456.

Abstract ( 684 )

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A series of cationic water-borne polyurethane(CWPU) was synthesized from isophorone diisocyanate (IPDI), polyneopentanediol adipate (P756) and hydrophilic N-methyl dihydroxyethyl amine (N-MDEA) by using the one-step process. Phase inversion of the cationic water-borne polyurethane was established by tracing the change of conductivity and speed of stirrer during the dispersion process.The conductivity of CWPU increased to a maximum, and then decreased to a stabe value.This result showed that the enrichment of partial anion and the gemination of ion occurred successively during the process of phase inversion.Conductivity kept stable after the Stern layer of the CWPU colloid particles were formed. The effects of dispersion temperature and the amount of N-MDEA on the particle size of CWPU were discussed. The particle size and polydispersity of CWPU were decreased with higher dispersion temperature and increasing amount of hydrophilic chain-extender. There existed optimal dispersion temperature and amount of chain-extender of the cationic polyurethane during the dispersion process. The DSC and DMA data of the cast film of CWPU showed that water could enter the partially disrupted ordered structure of the CWPU hard segment when phase inversion occurred at an appropriate temperature, and the stable, smaller particle size and polydisperse of the CWPU could be obtained.

Preparation and properties of amphiphilic hyperbranched poly(ester-amide)

TONG Shenyi;KOU Yuxia;LIU Xintai;ZENG Guangming;WEN Jinsong

2006, 57(2): 457-460.

Abstract ( 644 )

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A hyperbranched poly(ester-amide)(HP) with hydroxyl end-groups was synthesized from diisopropanolamine (DIPA) cis-1,2-clyclohexane-dicarboxylic anhydride (HHPA) and pentaerythritol (PETL), and a kind of amphiphilic hyperbranched macromolecule was prepared with the hydroxyl end-groups modified by the addition of polyethylene glycol monomethyl ether（MW550, MPEG550）.The structure of the macromolecules was characterized with IR, DSC, GPC and SEM.The results indicated that the hyperbranched poly(ester-amide) had narrow molecular mass distribution with polydispersity 1.47, and glass transformation temperature (T_g) 36℃.It was shown by SEM micrographs that the amphiphilic polymer in water solution exhibited nano-spherical particles dispersion with 50～100 nm diameter.

Preparation and characterization of biodegradable nanoparticles from methoxy poly(ethylene glycol)- poly (D,L-lactide)block copolymers as novel drug carriers

JIANG Wei;WANG Yundong;ZHANG Jianzheng;GAN Quan;ZHANG Hanwei;BEI Jianzhong;ZHAO Xiuwen;FEI Weiyang

2006, 57(2): 461-464.

Abstract ( 584 )

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Methoxy poly(ethylene glycol)-poly(D,L-lactide) block copolymers (PEG-PLA) were prepared through ring-opening polymerization.The oil in water suspension method was used to prepare block copolymer micelles. The critical micelle concentration (CMC) by fluorescence spectroscopy was 0.0056 mg•ml^-1. The physical state of the inner core region of micelles was characterized with 1HNMR. The size of indomethacin (IMC) loaded micelles measured by dynamic light scattering (DLS) showed narrow monodisperse size distribution and the average diameters were less than 50 nm. In addition, the nanoparticles with relatively high drug loading content (DLC) were obtained.

New technique of producing hydrogen and zinc sulfide from hydrogen sulfide

WANG Xiaoming;WANG Shujun;LIU Hongyan;LI Jianxiang;ZHANG Wei;WANG Wenbo;ZHANG Chen

2006, 57(2): 465-469.

Abstract ( 728 )

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A new technique of producing H₂ and ZnS from H₂S was studied with the electrochemical dissolution-precipitation method. The results showed that in the absorption reactor, where the temperature was 25～30℃, and the rate of stirring was 100 r•min^-1, the absorption rate of hydrogen sulfide (5%～100%) in one processing could reach 99.9% and high quality of zinc sulfide could be obtained. At the same time, in the electrolysis reactor, pure hydrogen could be obtained under the temperature 25～30℃, electricity voltage 0.5 V and electricity consumption 1.2 kW•h•m^-3H₂.