CIESC Journal

Calculation of vapor-liquid equilibrium for ionic liquid-containing systems with NRTL equation

SHI Qibing, ZHENG Fengchun, LI Chunxi, LU Guiwu, WANG Zihao

2005, 56(5): 751-756.

Abstract ( 706 )

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Ionic liquid as a benign solvent is of great potential to be used in chemical reaction and separation processes, and the modeling of vapor-liquid equilibrium(VLE) for the ionic liquid-containing systems is of both theoretical and practical significance.By using the NRTL equation for non-electrolyte solution, the VLE isotherms for ［bmim］［PF₆］-H₂O and ［C₈mim］［PF₆］-H₂O binary systems were correlated with deviation within 2% and the VLE data at other temperatures were predicted with the mean relative deviation within 5%.The experimental infinite dilution activity coefficients of some organic chemicals in ionic liquids C₈H₁₄S₂O₄F₆N₃ and C₉H₁₆S₂O₄F₆N₃ at different temperatures were correlated successfully with the NRTL equation,and the binary parameters thus obtained were used to study the effect of ionic liquid on the VLE of azeotropic binary systems. It was shown that VLE for ionic liquid-containing systems could be well represented with the conventional NRTL equation.The relative volatility of components could be largely affected and azeotropic point could even be eliminated by the “salt effect” of ionic liquid.

Modified model for correlating excess enthalpies of binary systems

CHEN Haisong, WANG Wenchang, WANG Fu’an, REN Baozeng, WANG Liucheng

2005, 56(5): 757-762.

Abstract ( 731 )

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Ordinarily Redlich-Kister equation and SSF equation are used for correlating excess enthalpies.Both equations are multinomials in which the number of parameters is undetermined.The equation with three parameters proposed by Liu Guojie has a fixed form, but besides three undetermined parameters, the molar volume of the solution needs to be known.A model with three parameters that does not have this demand was proposed by the present author, but the composition of solution is shown by mol fraction, so it is difficult to reflect the special effect of difference in molecular sizes.In this paper, a modified model for correlating the excess enthalpies of binary systems is developed in which the macro-composition of solution is shown with volume fraction to emphasize the special mutual effect of molecules caused by different molecular sizes.Tests with experimental data of more than 100 non-symmetrical binary systems in which the components have different molecular sizes, shapes and structures,show that for non-symmetrical binary systems the modified model is of an apparent advantage over the former one in accuracy, and is still tenable in the limiting condition of φ→0 and φ→1.

Molecular dynamics simulation of structural and dynamic properties of methanol under influence of external electric field

SUN Wei;CHEN Zhong;HUANG Suyi

2005, 56(5): 763-768.

Abstract ( 668 )

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Molecular dynamics simulations of liquid methanol were performed at 298 K and density of 0.78 g•cm^-3 under various applied external electric fields, ranging from 0—10¹⁰V•m^-1.Methanol was described by using the three-site OPLS potential model.The influence of the external field on structural and dynamic properties of methanol was investigated.An obvious structural change could be detected by the snapshots of methanol microscopic configuration without and with an electric field of 1.0×10¹⁰V•m^-1.Enhancement of the methanol hydrogen bond structure with increasing strength of the electric field was deduced from the radial distribution functions and the analysis of hydrogen bonds structure.The self-diffusion coefficient decreased with increasing strength of electric field, and the self-diffusion coefficient was anisotropic.

Application of molecular simulation for study of SBS modified asphalt

CONG Yufeng;LIAO Kejian;ZHAI Yuchun

2005, 56(5): 769-773.

Abstract ( 648 )

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The dissolution mechanism between SBS modifier and asphalt was studied with the Computer Aided Molecular Design(CAMD) method. One type of the base asphalt models was defined for 3D amorphous cell construction. Molecular Mechanics (MM) and Molecular Dynamics (MD) computations were carried out on these amorphous cell structures at customized temperatures to determine the lowest energy structures and hence the most stable configurations.The solubility parameters derived from the cohesive energy density (CED) of each amorphous cell system at different co-melting temperatures were calculated with the molecule modeling analysis module.Comparison of experimental and simulation data showed that the solubility of SBS line-shaped modifier in base asphalt was improved and reached that of star-shaped by adding a small amount of sulfur at co-melting temperature of 110℃. However,the solubility of both line-shaped and star-shaped modifiers is satisfactory at a higher temperature of 150℃ even without sulfur addition.The CAMD method could be useful in preparing SBS modified asphalt.

Conjugated heat transfer in micro-channel heat exchanger

CAO Bin;CHEN Guangwen;YUAN Quan

2005, 56(5): 774-778.

Abstract ( 736 )

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Conjugated heat transfer performance in a countercurrent micro-channel heat exchanger was analyzed and simulated by using the one dimensional gas convection and wall axial heat conduction model. The effects of structural parameters, operating conditions and heat conductivity of wall material on the performance of heat transfer of this micro-channel heat exchanger were investigated. The simulation results indicated that the properties of micro-channel heat exchanger were much different from those of conventional heat exchanger due to the synergetic effect of radial and axial heat conduction in the micro-channel heat exchanger.Low conductivity metal, such as stainless steel, is an excellent wall material and available for micro-channel heat exchanger. There existed an optimal operation flux, which could be used as a standard flux for a given micro-channel heat exchanger, and micro-channel heat exchanger was not suitable when the operation flux was lower than the standard flux. The maximum heat transfer efficiency of micro-channel heat exchanger decreased with increasing operating flux. The calculation results also showed that micro-channel heat exchanger with high aspect ratio channel and optimal wall width had higher efficiency than other configurations.

Nonlinear characteristics in vapor-liquid-solid flow boiling system

QIANG Aihong, LIU Mingyan, SUN Yongli

2005, 56(5): 779-785.

Abstract ( 682 )

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Chaos analysis of the dynamic behavior of temperature fluctuations in a vapor-liquid-solid three phases flow boiling system was conducted in terms of power spectral density function, autocorrelation function, reconstructed phase space, correlation dimension and Kolmogorov entropy.It was shown that the system was non-linear and chaotic. Two or three non-integer correlation dimensions and positive finite value of the Kolmogorov entropy were found in this system.The relationships between heat transfer characteristic and correlation dimension and that between heat transfer characteristic and Kolmogorov entropy were also discussed.Heat transfer coefficient increased with the increase of correlation dimension and Kolmogorov entropy.

Finite stochastic breakup model of air-blast atomization process

GONG Xin, LIU Haifeng, LI Weifeng, CHEN Mouzhi, QIN Jun, YU Guangsuo, WANG Fuchen, YU Zunhong

2005, 56(5): 786-790.

Abstract ( 690 )

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Droplet size distribution is an important parameter of atomization process.The finite stochastic breakup model of air-blast atomization process with four parameters:initial droplet diameter,diameter of maximum stable droplet,minimum mass ratio of a sub-droplet to the mother droplet and droplet breakup probability is presented according to the self-similarity of droplet breakup.The simulation results of droplet size distribution with this model agreed well with the experimental results of a three-channel nozzle with air and water, obtained by Malvern Laser Particle Sizer Type 3600 measurement.With this model, the nonlinear relationship between average droplet diameters and droplet size distribution of the airblast atomization process could be predicted satisfactorily.

Design and performance simulation of continuous solar powered adsorption air conditioning system

LIU Yanling;WANG Ruzhu;XIA Zaizhong

2005, 56(5): 791-795.

Abstract ( 699 )

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This paper presents the simulation of a solar-powered continuous adsorption air-conditioning system with the working pair of silica gel and water.In order to make the adsorption system more suitable to using solar energy for cooling continuously during daytime, a new adsorption system without refrigerant valves was developed in SJTU recently.By using this system, such problem as pressure drop along refrigerant circuit could be resolved.The frequent switches of refrigerant valves could also be eliminated.The daytime simulation results (from 6:00AM to 18:00) demonstrated that by using 40 m² solar collector area, the adsorption system could supply a fairly steady cooling output about 5—8 kW with system COP over 0.2 all the time.Based on the results, parametric study was also made to optimize the design.The simulation results and theoretical analysis could provide guidance for practical work.

Multi-Monte Carlo method for simultaneous coagulation and condensation/evaporation of polydisperse particles

ZHAO Haibo;ZHENG Chuguang;XU Minghou

2005, 56(5): 796-801.

Abstract ( 709 )

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The time evolution of particle size distribution (PSD) is of fundamental interest and a key issue.PSD along with time is described by general dynamic equation (GDE).There is an antinomy of computation cost and computation precision in some ordinary Monte Carlo methods for GDE. A new multi-Monte Carlo (MMC) method is presented to consider GDE for simultaneous coagulation and condensation/evaporation of polydisperse particles.The MMC method is based on time-driven, constant number technique and constant volume technique.Firstly the MMC method is described in detail, including the setting of time step, the scheme of handling simultaneous coagulation and condensation/evaporation.Then the MMC method is validated by three kinds of special cases:constant coagulation kernel and constant condensation kernel(case1),constant coagulation kernel and linear condensation kernel(case2),and linear coagulation kernel and linear condensation kernel(case3).The simulation results of the MMC method for GDE agreed with analytical solution well, which proved that MMC method could resolve the contradiction between computation cost and computation precision, i.e., MMC method has both lesser computation cost and better computation precision.

Diffusion and reaction model in deoxidizing resin layers of oxygen absorbing multi-layer films

WANG Cheli;CHENG Minlian;QIU Zhaorong

2005, 56(5): 802-806.

Abstract ( 705 )

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A variety of deoxidizing resin films were prepared, which were key layers of the oxygen absorbing multi-layer films.The effects of iron content, iron particle size, metal halide content, coupling agent, inorganic filler, and moisture regulating time on oxygen-absorbing rate were investigated.A model of oxygen-absorbing rate in deoxidizing resin films was developed based on the quasi-steady state assumption. According to the model, if M^1/2＞3, the process was a rapid reaction,and the film thickness had no effect on oxygen-absorbing rate.But when M^1/2＜0.3,the process was a slow reaction, the diffusion coefficient D_eshowed no effect on oxygen-absorbing rate, and the oxygen concentration in the film was uniform and equal to that at gas-solid interface.The experimental results of oxygen-absorbing rate in deoxidizing resin films agreed well with the model proposed.

R407C Incomplete phase changing in heat pumps and its influence on system parameters

ZHAO Li

2005, 56(5): 807-811.

Abstract ( 577 )

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In order to reveal some relationships between system parameters and R407C incomplete phase changing in condenser and evaporator, a concept is presented firstly, that is the maximum flow rate of heat-transfer fluids. Afterwards thermodynamics cycle analyzing is used, and some important system parameters are given, such as temperature difference between R407C and heat-transfer fluids, compressor discharge capacity. These parameters can affect on the maximum flow rate of heat-transfer fluids, and the results are shown in some figures. Lastly, relationship is discussed too between R407C’s pressure drop in condenser or evaporator and the incomplete phase change.

Inner structure and evolution of boiling nucleus

WANG Xiaodong;TIAN Yong;PENG Xiaofeng;WANG Buxuan

2005, 56(5): 812-815.

Abstract ( 730 )

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The classical nucleation theory does not give a clear description of the formation of the nucleus and the interfacial properties between the nucleus and the bulk phase are the same as that of macroscopic liquid vapor interface. The latter hypothesis resulted in considerable difference of the nucleation rate predicted by the theory from that experimentally measured. In this paper a model of two-region structure of a nucleus is proposed to describe nucleus evolution. The nucleus is composed of a central region and a transition region. The central region with radius r₁, can be regarded as a pure vapor region with density ρ_v. Meanwhile, the transition region surrounds the central region, and its density varies linearly from ρ_vof the central region at r₁, to ρl of the bulk liquid phase at r₂.The active molecules first aggregate and grow up in the transition region, which convert into vapor phase close to the boundary of the central region and aggregate inside the central region. When the transition region approximately decreases to a thickness of several molecular spacings,normal geometrical liquid-vapor interface is formed, the evolution of the nucleus completes and an ultimate vapor bubble with stable liquid-vapor interface is generated.With the interfacial tension calculated by using this model, the predicted nucleation rate is very close to the experimental measurement. Furthermore, this model and associated analysis provide solid theoretical evidence to clarify the definition of nucleation rate and understand nucleation phenomenon with the insight into the physical nature.

High-density gas-solids flow in downer-riser coupled circulating fluidized bed

LI Zhiqiang;WU Changning;WEI Fei;JIN Yong

2005, 56(5): 816-822.

Abstract ( 668 )

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Experimental studies were carried out in a specially designed high-density “riser-downer-riser” coupled circulating fluidized bed system. Fluidized catalytic cracking (FCC) particles were used.Compared with the primary air rate, the secondary air rate had an important effect on the solids circulation flux. When the solids circulation flux was 400 kg•m^-2•s^-1, the apparent solids holdup exceeded 20% near the top of the first riser, and the volumetric solids fraction (apparent solids holdup) was larger than 5.5% in the fully developed region of the downer.With increasing solids circulation flux, more uniform solids concentration distribution along radial direction could be obtained.

Particle trajectory in vortex classifier rotor

DU Yanchen;WANG Shulin

2005, 56(5): 823-828.

Abstract ( 638 )

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A simplified single particle dynamic model is proposed to study the particle trajectory in the classifier rotor.The particle movement in the radial direction is assumed resulting from local equilibrium of two forces, the air drag force and the centrifugal force. By this equilibrium, the fine and coarse particles to be separated have different trajectories in the classification zone. For the convenience of finding the solution, the original governing equation is converted to one in rotating coordinate system. Particle trajectories are determined according to different rotor rotating speeds, different gas flow rates, different blade spaces, and different blade angles. Numerical results show that the increase of the rotating speed and the decrease of the gas flow rate can significantly reduce the cut size. Narrow blade space causes more collision between particles and the wall. With respect to decreasing the cut size of the classifier,the blade with negative angle is better than that of zero angle, and zero angle is better than positive angle, while other parameters of the vortex classifier are kept the same.

Numerical simulation of swirl-spray precalciner

HUANG Lai, LU Jidong, REN Hebin, LIU Zhijiang, DI Dongren, HU Zhijuan

2005, 56(5): 829-834.

Abstract ( 629 )

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The new type swirl-spray precalciner used in cement plant is a large-scale and complex reactor in chemical engineering.In this work a full three-dimensional numerical simulation is carried out for swirl-spray precalciner, and at the same time a new method for particle trajectory in rectangular-structural grid is presented.The results of simulation disclose and predict the physicochemical process of precalciner and the numerical simulation results agree well with the experimental results.

Preparation of methylcyclohexanol and methylcyclohexanone from aerobic oxidation of methylcyclohexane catalyzed by metalloporphyrins

MA Jinyong;GUO Cancheng

2005, 56(5): 835-840.

Abstract ( 789 )

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The method for the preparation of methylcyclohexanone and methylcyclohexanol via selective aerobic oxidation of methylcyclohexane catalyzed by metalloporphyrin was reported for the first time.Catalyzed by Mn(Ⅲ) porphyrin, methylcyclohexane could be oxidized by air.The products were three isomers of methylcyclohexanone, 1-methylcyclohexanol and 2-methylcyclohexanol. The effect on the conversion and selectivity was investigated when reaction conditions or porphyrin structure were changed.With the alkoxyl substituting metalloporphyrins as catalysts,the selectivity of methylcyclohexanone and methylcyclohexanol was better than using TPPMnOAc.Moreover, the larger the substitute’s volume, the higher the conversion, and selectivity still remained satisfactory.Using 5,10,15,20-tetra(para-heptaneoxylphenyl) porphyrin manganese as catalyst, the conversion was up to 20% and the overall selectivity of methylcyclohexanone and methylcyclohexanol was 76%.

Secondary reactions of catalytically cracked gasoline

WANG Longyan;YANG Bolun;WANG Zhiwen;YANG Xiaohui

2005, 56(5): 841-846.

Abstract ( 751 )

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The ideal reactions and non-ideal reactions for reducing gasoline olefin and sulfur, and increasing propylene were proposed by analyzing potential secondary reactions of catalytically cracked gasoline. The secondary reactions of FCC nathpha on REUSY, ZRP and MO-REY zeolite catalysts were investigated in a FCC pilot plant with riser reactor to determine the product distribution of secondary reactions and properties of the upgraded gasoline. Effects of operating intensity on conversion and selectivity of gasoline secondary reactions were also investigated by experiments.The results indicated that lighter dry gas,LPG rich in propylene,heavier diesel and coke were produced by secondary reactions of FCC nathpha under the catalysis of Y or ZRP zeolite catalysts. In comparison with the FCC nathpha feeds, olefinicity and sulfur content of the upgraded gasoline derived from secondary reactions decreased greatly, and aromatics content and octane number increased evidently.Conversion and selectivity of gasoline secondary reactions depended on the olefin content of feed gasoline, the zeolite type of catalysts and the operating intensity of reaction process.

Preparation and characterization of novel fixed-bed Raney nickel catalyst and activity evaluation for benzene hydrogenation

BAI Rui;ZHAO Huiji;LIU Chenguang

2005, 56(5): 847-851.

Abstract ( 869 )

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An activated novel fixed-bed Raney nickel catalyst for hydrogenation of benzene to cyclohexane was prepared by extruding the Ni-Al alloy powder, sesbania cannavina (S.C.) powder with binding materials made of pseudoboehmite, calcining the extrudates in air at a high temperature, and leaching out the aluminum with caustic solution. The experimental results showed that the alloy phase rich in aluminum was gradually transformed into the phase poor in aluminum during the calcination of the alloy extrudates and a small part of aluminum in Ni-Al alloy was oxidized to α-alumina to increase the catalyst compressive strength.The analysis results of SEM and BET showed that wider aperture and abundant macroporosity existed on the catalyst surface.The results of benzene hydrogenation suggested that the novel catalyst showed a higher hydrogenation activity than γ-alumina supported nickel catalyst and the same type of fixed-bed Raney nickel catalyst prepared according to the patent methods.

Oxidative degradation of macromolecular constituents of heavy oil in ［(MoO₂)(acac)₂］/t-BuOOH/H₃PO₄ catalyzed oxidative degradation system

ZOU Changjun;HUANG Zhiyu;LUO Pingya

2005, 56(5): 852-856.

Abstract ( 697 )

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This paper illustrates the reaction pattern of catalytic oxidative degradation of macromolecule constituents in heavy viscose oil.Parameters, include reaction time, catalyst system and the catalytic function of the oil-bearing layer minerals at various conditions that affect the change in viscosity and average molecular mass of the heavy oil, were investigated in detail. It was found that in the ［(MoO₂)(acac)₂］/t-BuOOH/H₃PO₄/oil-bearing layer minerals system, the degradation of asphaltenes reached 81%, the viscosity of heavy oil fell from 117.2 Pa·s to 55.8 Pa·s, reduced by 52.4% and the average molecular mass fell by 100.The TLC-FID analysis indicated that the asphaltenes in heavy oil were transformed into resin, aromatics and saturates.The resulting physico-chemical changes enhanced the stability of the oil system.It could be beneficial in the exploitation, transportation and processing of heavy oil.

Environmentally benign method for synthesis of cinnamaldehyde

LV Xiuyang, HE Long, LU Cheng, GAO Fei

2005, 56(5): 857-860.

Abstract ( 768 )

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An environmentally benign method for synthesis of cinnamaldehyde with near-critical water as reaction medium was proposed.The results showed that cinnamaldehyde could be synthesized successfully through the reaction of phenylaldehyde with acetaldehyde in near-critical water without adding any catalyst.The effects of temperature and reaction time on the conversion of phenylaldehyde and yield of cinnamaldehyde were determined from 220 ℃ to 300 ℃.The yield of cinnamaldehyde was up to 16.6% after 5 hours reaction time at 260 ℃, 16 MPa,volume ration of reactants to water 1∶15.

Syntheses and properties of two aromatic polyketones

XU Yongshen;GAO Weiguo;LI Hongbing;GUO Jintang

2005, 56(5): 861-864.

Abstract ( 588 )

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The alternating copolymerization of carbon monoxide(CO) with styrene(St) or p-ethyl styrene(ESt) was catalyzed by the transition metal Pd(Ⅱ) complexes.The polyketones of STCO and ESTCO are both regular alternating copolymers. Coplymerization kinetics show that ESt/CO system is more active than St/CO system, but the life of reactivity in ESt/CO system is shorter than that of St/CO system in the batch copolymerization processes due to drop of CO pressure.It seems that higher CO pressure is needed to match alternating coordination and chain propagation in copolymerization of ESt/CO. This is an evidence that the more active the olefin, the higher the CO pressure needed.Additionally, introducing p-ethyl group to styrene make the melting point and crystallinity of ESTCO a little lower than those of STCO and the solubility in some organic solvents is improved.

Bi-Si mesoporous zeolites（Ⅱ）Reaction mechanism and optimisation of reaction conditions in styrene oxidation

CHEN Xiaohui;SU Jianfeng;WEI Kemei

2005, 56(5): 865-869.

Abstract ( 592 )

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Bi-Si mesoporous molecular zeolites(Bi-Si) was synthesized by the hydrothermal method with ethyl silicate （TEOS）as silica source, Bi(NO₃)₃·5H₂O as Bi source, and cetyltrimethylammonium bromide（CTAB）as template. Bi-Si catalyst had high ordering structures and high reaction activity in oxidation of styrene with hydrogen peroxide to benzaldehyde. The effects of solvents, reaction time, reaction temperature, oxidant concentration and Bi-Si concentration on the oxidation of styrene to benzaldehyde were studied systematically. It was found that in the following reaction conditions: catalyst 0.075 g, styrene 1.5 ml, methanol 25 ml，H₂O₂(30%) 4.5 ml，T=80 ℃，t=2 h，the conversion of styrene was 43.1%, the selectivity to benzaldehyde was 73.5%,the yield of benzaldehyde reached 31.7%.The possible reaction mechanism could be that one styrene molecule reacted with two H₂O₂ molecules on two joined catalytically active sites.

Optimal temperature-time policy of ethylene oxide synthesis reactor

HUANG Qi;WANG Hongshi;LING Zeji

2005, 56(5): 870-874.

Abstract ( 745 )

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The deactivation kinetics equations of ethylene oxide synthesis silver catalyst were obtained from the calculation of real industrial data.The equations could represent the characteristics of catalyst deactivation. On the basis of the deactivation model, the boiling water temperature-time policy of ethylene oxide synthesis reactor was optimized.The optimal curve of boiling water temperature was obtained.It could enhance the economic benefits of ethylene oxide synthesis.Feasible approaches to optimizing reactor temperature of the same series of new catalysts were recommended.

Catalytic performance of SO^2-₄/Fe₂O₃nanosolid superacid

XIONG Guoxuan, FAN Congbin, XU Wenyuan, HUANG Haiqing

2005, 56(5): 875-878.

Abstract ( 763 )

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In order to minimize the pollution of ferrous sulfate, a by-product of titanium dioxide, and increase the yield of synthetic ester, the SO^2-₄/Fe₂O₃ nanosolid superacid has been produced by chemical precipitation and its micrographs was determined by SEM. The effect of preparation conditions of SO^2-₄/Fe₂O₃ nanosolid superacid on catalysis synthesis butyl acetate and synthesis conditions of butyl acetate were studied.From experimental data,as compared with liquid acid, SO^2-4/Fe₂O₃ nanosolid superacid showed higher catalytic performance in catalytic synthesis of butyl acetate,and the yield of butyl acetate was obviously increased in the same reaction time.

Photocatalytic behavior of TiO₂ and ZnO prepared with different methods

PENG Feng ;CHEN Shuihui;WANG Hongjuan;HUANG Lei

2005, 56(5): 879-882.

Abstract ( 600 )

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Chelating-supercritical fluid extraction of metal ions from soil

ZHANG Guoying;LING Jianya;CUI Zhaojie

2005, 56(5): 883-884.

Abstract ( 668 )

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The method of using trifluoro acetyl acetone as chelating agent to extract Cu2+,Hg2+,Pb2+,Zn2+,Cd2+,Cr3+ from silica gel and soil sample by supercritical CO₂ was investigated.The extracts were analyzed with the atomic absorption spectrophotometry method. The experimental results showed that at 20 MPa,60 ℃ and with methanol as modifier, the metal ions mentioned above could be extracted efficiently. The recovery values for the simulated silica gel samples and soil sample were 91.0%—98.2% and 77.8%—93.9％, respectively. This method was proved to be simple, quick and without pollution, which could be applied to the analysis of heavy metal ions in environmental samples.

Method of process monitoring based on blind source separation with denoised information by wavelet transform

CHEN Guojin;LIANG Jun;QIAN Jixin

2005, 56(5): 885-889.

Abstract ( 634 )

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In this paper, a new process monitoring method is presented based upon wavelet transform and blind source separation. At first, wavelet transform is employed to de-noise measured signals to remove the process noise. Then blind source separation based on information maximization is used to extract blind source signals of the process. After this, process control limits and monitoring plots are built by estimating the probability distribution of every blind signal by means of Parzen density estimator. For investigating the feasibility of this method, its fault-detection performance is evaluated and compared with other method also based on blind source analysis directly with process information by applying it to a continuous-stirred-tank-reactor process. The results show the superiority of the method presented in this paper over other process monitoring method, which has high false alarms and missing alarms.

Dynamical model of RBF neural network-based prediction for heat transfer oscillating behavior of thermosyphon

CHEN Yanze, DING Xinwei, YU Jianliang

2005, 56(5): 890-893.

Abstract ( 697 )

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The work address the problem of modeling the dynamical oscillating behavior during both unstable and stable operations, of an experimental thermosyphon. A standard RBF artificial neural network-based prediction model was developed for predicting the oscillating heat transfer of thermosyphon by means of input-output experimental measurements with the characteristics of time series. A comparison of prediction values between the RBF network and the MLP network was giving.The precision of RBF network was higher than that of the other neural networks such as BP-MLP network etc. The dynamical model of RBF network could be used to describe, predict and control the heat transfer process of a thermosyphon or a heat pipe system.

Dynamic lattice Monte Carlo simulation of adsorption of nonionic-surfactants on oil-water interface

WEI Yilong;RONG Zongming;LIU Honglai;HU Ying

2005, 56(5): 894-899.

Abstract ( 685 )

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Dynamic lattice Monte Carlo simulation was used to study the adsorption of symmetric and unsymmetric
nonionic-surfactants at the water-oil interface.The time needed to reach equilibrium,the numbers of the surfactant on the interface, the thickness of the interface between water and oil phases, the density distribution of segments A and B in the system and the interfacial tension,both static and dynamic were obtained and the effect of the structure and concentration of the nonionic-surfactants on these properties was studied too.The time needed for the system to reach equilibrium was related to the structure and concentration of the nonionic-surfactant.For the nonionic-surfactant with the same structure,the time increased when concentration of the surfactant increased under the situation that the concentration was below CMC.The time was determined by the length and structure of the chain when the number concentration was same.The symmetry of the density distribution curve of segments A and B was related to the composition of the nonionic-surfactant.The surface activity of nonionic-surfactant was decided by its structure mainly.For symmetric nonionic-surfactant, it was more active as its length increases.For unsymmetrical one, it was determined by the structure; The interfacial tension decreased as the concentration of the nonionic-surfactant increased and would not change when it reached a stable value when the length of the nonionic-surfactant is same.

Influence of impure ions on performance of solid polymer electrolyte water electrolyser

DONG Zhiwu;ZHOU Yuanquan

2005, 56(5): 900-903.

Abstract ( 719 )

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The effect of impure ions on the performance of the solid polymer electrolyte water electrolyser（SPEWE）was studied. While impure ions were added into the anode compartment of the SPEWE, the variations of cell voltage, anode and cathode potentials with electrolysis time were analyzed respectively.The investigations revealed that these impure ions did great harm to the performance of the SPEWE.The rapid increasing cell voltage was mainly due to the increase of cathodic overvoltage.Ni2+,Cu2+electrodeposited at the interface between the cathode catalytic layer and Nafion membrane, and covered cathodic catalysts and decreased reaction active sites.Ca2+,Mg2+ formed a layer of hydroxide ,which had so bad electron conductivity that it not only covered cathodic catalysts but also increased interface contact resistance, resulting in rapid increase of cathodic overvoltage.

Mathematical model for analysis of cell cycle arrest and
apoptosis induced by docetaxel

CAO Dongxu;QIAO Bin;GE Zhiqiang;YUAN Yingjin

2005, 56(5): 904-910.

Abstract ( 793 )

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A mathematical model of in vitro cancer cell growth differentiated by cell cycle distribution and antimitotic drug interaction was presented in this paper. The model was adapted to the growth and treatment of human leukemia K562 cells with docetaxel.It described docetaxel-induced apoptosis, G2/M phase arrest as well as the relationship of drug concentration and cell response manners.The model showed that the saturation docetaxel concentrations to cause M-phase arrest and apoptosis in K562 cells were 17.96 nmol·L^-1 and 7.82 nmol·L^-1 and the effective concentrations were 2.63 nmol·L^-1 and 1.69 nmol·L^-1,respectively.Low concentration docetaxel (1.69—2.63 nmol·L^-1) induced apoptosis directly, without obvious M-phase arrest,while cells mainly reacted with concentration-dependent M-phase arrest and saturated apoptosis at high concentration docetaxel (>7.82 nmol·L^-1).The model indicated that M-phase arrest was not positively related to apoptosis, which gave a new explanation for the mechanism of docetaxel.

High pressure extraction of total ginsenoside at room temperature

CHEN Ruizhan;ZHANG Shouqin;WANG Changzheng

2005, 56(5): 911-914.

Abstract ( 1087 )

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A new extraction process, named high pressure extraction (HPE) at room temperature, was used to extract ginsenoside from ginseng. The extraction process of HPE was optimized with the uniform test design method. The optimum HPE process conditions of ginsenoside were: solvent 50% ethanol, pressure 200 MPa, ratio of raw ginseng(g) to solvent(ml) 1∶100, extraction time 1 min,yield 7.32%. Compared with the cooking,reflux extraction,ultrasonic and supercritical CO2 extraction processes, HPE have many advantages, such as higher yield, no heating, shorter extracting time and energy saving. HPE provides a new process for the extraction of ginsenoside from ginseng at room temperature.

Effect of radical source on nitrogen oxide removal by DC corona radical shower

WU Zuliang;GAO Xiang;WEI Enzong;ZHANG Jizhou;LI Mingbo;WU Zucheng;LUO Zhongyang;NI Mingjiang;CEN Kefa

2005, 56(5): 915-919.

Abstract ( 644 )

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NH₃,O₂,N₂ and vapor are commonly used gases to generate N,H,O radicals.In this work,NH₃+Ar,O₂,dry air and humid air were selected as working gases of radical sources to research NO removal.It was shown that stable corona could be formed by different radical sources. However, they had certain effect on discharge characteristic. The conversion rate of NO into NO₂ by air and oxygen was obviously higher than that by NH₃+Ar.NO₂ was easy to be absorbed by lye and greenhouse gases,N₂H and N₂O, were produced when adding NH₃+Ar.Therefore air and oxygen were better radical sources.When air was injected into the electrode,NO removal efficiency was a little worse than the case of oxygen but almost the same as the case of NH₃+Ar.However, considering safety and economy, air has a better prospect of application.A few water vapor was helpful to improve NO removal.Humid air was the best choice among NH₃+Ar,O₂,dry air and humid air.

Numerical modeling with multiphase flow model of petroleum pollutant transport in subsurface environment

XUE Qiang;LIANG Bing;FENG Xiating;LIU Jianjun

2005, 56(5): 920-924.

Abstract ( 644 )

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A coupled multiphase flow model was established to predict transient flow and petroleum pollutant transport in subsurface environment.The model accounted for the complex process of dispersion, absorption/desorption,distribution between liquid-solid interfaces and microbiological degradation under the assumption of local chemical equilibrium.Solutions of the coupled equations were accomplished by the characteristic finite difference method and implicit pressure explicit saturation method.The code was developed for simulating petroleum pollutant transport and migration mechanism in porous media.Numerical results showed petroleum pollutant leaking into subsurface environment,with vertical and horizontal displacement under gravity and capillary pressure.As pollutant migrated into the capillary zone,capillary tension restricted the vertical movement.The pollutant must overcome the entrapment pressure of oil-water interface before entering the capillary zone, and pollutant accumulated on the top of the capillary zone to become pressurized.The pore pressure of pollutant exceeded the entrapment pressure of oil-water interface,and pollutant entered the capillary zone and formed a lens above the groundwater level. The model simulations were compared with experiential measurements of petroleum pollutant mass distribution in soil, and there was reasonable agreement between model simulation and measured data.It provides theoretical evidence for studying distribution and destination of organic pollutant transport in subsurface environment.

Synthesis of ultrafine MnO₂ powders by spray-drying and characterization

ZHAO Fengming;MA Chun’an;TONG Shaoping;CHU Youqun

2005, 56(5): 925-931.

Abstract ( 780 )

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A spray-drying method was developed to synthesize MnO₂ cathode materials and measurements of XRD,SEM and electrochemistry were performed to characterize the properties of the prepared materials.Experimental results showed that Mn₂O₃ was formed during heat-treating and changed to γ-MnO₂ after acid treating.The precursor had the shape of a globe, and then cracked when being sintered.The initial discharge capacity reached 215mAh·g^-1 and 70% DOD with respect to the first one-electron reduction of γ-MnO2.It could be higher by 15% than EMD.Combined with cathodic polarization and AC impedance, the finite diffusion model was used to interpret the proton diffusion inside the lattice of MnO₂.

Optimization of preparation of GMA/MBAA/AA macro-porous copolymer using factorial design

ZHOU Wuyuan;NING Fanghong;LIU Zuozhen;WU Xingyan

2005, 56(5): 932-936.

Abstract ( 1051 )

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The aim of the study was to optimize polymerization conditions so as to maximize the binding capacity for proteins, using BSA as a model substance.A macro-porous hydrophilic bead copolymer was synthesized by organic two-phase suspension polymerization,with glycidyl methacrylate and acrylamide as monomers, N,N′-methylene-bis(acrylamide) as a crosslinker and formamide as the dispersion phase, behaving as porogenic agent, the continuous phase being n-heptane. The characteristic features of the copolymer were studied, including specific surface area, pore diameter, pore volume and distribution, and the content of oxirane groups as well.It was known from past experience that the cross-linking degree, amount of GMA and amount of formamide were the three main factors affecting the BSA adsorption capacity.For exploring their effects and all possible interactions, a 2³ complete factorial design was used in experiment.Its analysis showed their effects in the order:cross-linkage>GMA amount>formamide amount, while the three two-factor interactions and the three-factor interaction were attributable to experimental error or noise.Consequently the estimated response(BSA adsorption capacity) could be expressed with a linear function of three main variables.Follow-up investigations found maximum adsorption capacity of 25.6 mg·g^-1 wet resin against the original 9.1 mg·g^-1 wet resin.

Calcination synthesis of potassium hexatitanate whiskers with low content of water soluble potassium ions

WANG Changsong;FENG Xin;SHI Yijun;LU Xiaohua

2005, 56(5): 937-941.

Abstract ( 694 )

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Water soluble potassium ions in potassium hexatitanate whiskers (PTW) of calcination synthesis were investigated in this paper.Experiments showed that the dissolved potassium ions were stripped slowly and not derived from the crystal structure of PTW.With the increase of the concentration of potassium ions the pH value of PTW suspension increased.The analysis based on the experimental results and growth mechanism of PTW showed that there should be trace K₂O between nano-structure gaps on the surfaces of PTW.Thus the trace K₂O between nano-structure gaps led to water soluble potassium ions in PTW.Moreover, potassium ions could be reduced effectively by soaking PTW in dilute acid solution for 8 h or ultrasonic cleaning, and the PTW fit for composites were obtained.The coating of shell (SiO₂) on PTW might hinder dissolution of water soluble potassium ions,but the modification of silanes(A186) on PTW had no influence on the dissolution.

Synthesis and study of calcium phosphate nanowires in microemulsion

LAI Chen, TANG Shaoqiu, WANG Yingjun, WEI Xiaokun, ZHANG Shiying

2005, 56(5): 942-946.

Abstract ( 902 )

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Calcium phosphate nanowires could be obtained in the reverse microemulsions of nonionic surfactant and ionic surfactant. Amorphous calcium phosphate nanowires with 325 nm in length and 13 nm in width could be prepared in water/ C₁₂E₈(polyethylene glycol alkyl ethers)/cyclohexane system while well-crystallized calcium phosphate with 500 nm in length and 14 nm in width could be prepared in the system of water/CTAB(cetyltrimethy lammonium bromide)/cyclohexane. However, the mechanism of the growth of crystal in these two kinds of system was entirely different.C₁₂E₈ in reverse microemlusion played a role of “microreactor”.With the assistance of CTAB, well-crystallized calcium phosphate nanowires could be obtained, in which surfactant CTAB acted as guiding the growth direction, but not serving as microreactors.

Preparation of nano-crystalline tungsten carbide thin film electrode and its electrocatalytic activity for oxidation of methanol

ZHENG Huajun, MA Chun’an, HUANG Jianguo

2005, 56(5): 947-951.

Abstract ( 767 )

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Nano-crystalline tungsten carbide thin films were fabricated on graphite substrates by plasma enhanced chemical vapour deposition in H₂ and Ar atmosphere, using WF₆ and CH₄ as precursors.The crystal phase, structure and chemical components of the films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS),respectively.The results showed that the film prepared at CH₄/WF₆ concentration ratio of 20,working pressure of 100Pa and temperature of 800℃ were composed of sphere particles with a diameter of 20—35 nm Electrochemical investigations show that the electrochemical surface area of electrode of the film was large.The electrode of the film exhibited higher electro-catalytic activity in the reaction of methanol oxidation,and its catalytic properties were similar to those of Pt or Pt group catalysts.The constant current of the film catalyst was 123.6 mA·cm^-2 in the mixture solution of H₂SO₄ and CH₃OH at the concentration of 0.5 mol·L^-1 and 2.0 mol·L^-1 respectively at 70 ℃, and its constant potential was only 0.306 V(vs.SCE).