CIESC Journal

APPLICATIONS OF DNA SHUFFLING AND GENOME SHUFFLING IN METABOLIC ENGINEERING

CHEN Tao;CHEN Xun;WANG Jingyu;BAN Rui ;ZHAO Xueming

2004, 55(11): 1753-1758.

Abstract ( 897 )

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Metabolic engineering is the combination of applied molecular biology and reaction engineering.It has become the platform technology for strain improvement.In the post-genomic era, genomics, transcriptomics, proteomics and metabolomics provide great opportunity for the development of metabolic engineering.In addition to new pathway construction, DNA shuffling and genome shuffling are applied to rapid optimization of known or unknown pathway, which greatly promotes the development and applications of metabolic engineering. DNA shuffling and genome shuffling methods can increase our understanding of metabolic networks and their molecular regulation mechanisms，integrating and complementing rational metabolic design strategies. This review illustrates the applications of DNA shuffling and genome shuffling in metabolic engineering and prospects the perspective and methodology in metabolic engineering by genome shuffling.

CONVECTION HEAT TRANSFER OF CONVERGING-DIVERGING TUBE（Ⅰ）MECHANISM OF FIELD SYNERGY PRINCIPLE

CHEN Ying;DENG Xianhe;DING Xiaojiang

2004, 55(11): 1759-1763.

Abstract ( 677 )

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The present paper discusses the results of a numerical simulation about the performance of the single-phase convection heat transfer in converging-diverging tube.The mechanism of field synergy principle presented by Guo was conducted to reveal how to augmenting heat transfer when fluid is a fully developed turbulent flow.Some parameters are investigated on how to distribute along the stream-wise direction in the tube, such as the thermal boundary layer thickness, the turbulent intensity,the intersection angles between time-averaged velocity and time-averaged temperature gradient and the local Nusselt number.Numerical result reveals that the variations of T•cosθ are similar to the local Nusselt numbers along the stream-wise direction.The variation of the two parameters indicates that an enhanced cooperative interaction of velocity vector and temperature gradient vector will be created in the converging section, so a better field synergy is gained and heat transfer is augmented here.In the meantime, a worse field synergy is obtained in the diverging section.A comparison between two converging-diverging tubes is presented, which have different converging length while keeping the other geometrical parameters constant, such as rib pitch, rib height and tube diameter.Tube 1 with a longer converging length shows a better field synergy than Tube 2 with a shorter one.Hence heat transfer is enhanced when the converging length is longer.

CONVECTION HEAT TRANSFER OF CONVERGING-DIVERGING TUBE(Ⅱ) OPTIMAL GEOMETRY CONFIGURATION

CHEN Ying;DENG Xianhe;DING Xiaojiang

2004, 55(11): 1764-1767.

Abstract ( 812 )

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According to the physical mechanism of the field synergy that controls the turbulent fluid heat transfer in the converging-diverging tube, an enhanced heat transfer structure is proposed here, that is to extend the converging section length as far as possible while retaining the optimal rib height and pitch and the tube diameter obtained by Мигай.A numerical study has been carried out to investigate the heat and flow characteristics of the converging-and-diverging tube with different converging length ratio.The results of numerical study indicate that increasing the converging length ratio can augment the synergy effect of the velocity and heat flux vector fields.Additionally, different types of way how to joint the converging section with diverging one are compared and the jointed convexly way is found to be the best among them.Therefore a developed geometry configuration is presented in the paper.A 4.67%—8.34% increase of Nusselt number is observed and a 7.87%—15.22% increase of friction factor is detected for the developed configuration (Re=1.5×10⁴—5×10⁴).Finally, Webb’s comparison method is adopted to evaluate the combined performance of the developed tube.The performance evaluation factor of the developed tube is η=1.008—1.06 against the Reynolds number in the range of 1.5×10⁴—5×10⁴ as compared with the optimal configuration proposed by Мигай, whose converging length is twice the diverging length.

EXPERIMENTAL STUDY ON THERMOSIPHON BY ADDING NANOPARTICLES TO WORKING FLUID

PENG Yuhui;HUANG Suyi ;HUANG Kunjian

2004, 55(11): 1768-1772.

Abstract ( 778 )

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A new method of enhancing heat transfer of the heating section of a two-phase closed thermosiphon was proposed.Theoretical and experimental studies were carried out on the performance of heat transfer enhancement by adding a proper amount of nanoparticles to the thermosiphon with water as working fluid.This thermosiphon showed such advantages as good startup,lower tube wall temperature,increased heat transfer coefficient by 47%—96%,and increased heat flux by 7.6%—15% in the range of the experiment.This method is simple and easy to use in chemical industry.

APPLICATION OF HYDROPHOBIC MATERIALS TO DIGITAL SUPER MICRO VOLUME MICROINJECTION

MU Lili;ZHANG Weiyi;HOU Liya;ZHAO Yaojun;SHA Jingjie

2004, 55(11): 1773-1776.

Abstract ( 704 )

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In biomedical engineering and micro chemical analysis,the microinjection system based on glass micropipette often have some disadvantages such as seepage or regurgitation during injection because of glass hydrophilicity.It is difficult to detect and control the system and the injection effect from micro pipette is also affected.This paper presents a novel technology of hydropholic treatment.The designated region of inner and outer micropipette surface is treated in a hydrophobic way.The droplet is injected with a spherical shape when liquid flow is driven and controlled digitally,which improves greatly the injection effect,and the amount of injected fluid which may reach an ultra high resolution of the order of femtoliter can be accurately detected and controlled.The validity of the presented method is verified by experiment.

RADIAL DISTRIBUTION CHARACTERISTICS OF LOCAL PARTICLE VELOCITY FOR BINARY PARTICLE MIXTURE IN DOWNERS

ZHU Yuan;ZHANG Jiyu;XIE Kechang

2004, 55(11): 1777-1786.

Abstract ( 736 )

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The axial and radial distributions of the local particle velocities at different radial positions on various axial levels along the downer-column were measured by using a PV-4A fiber-optic particle velocity probe in a half-column downer of 2m high and 30mm I.D.,and the effects of operation conditions and spouted positions on the local particle velocities were also investigated in this paper. Then the radial particle velocity distributions of binary particle mixture，formed by respectively and simultaneously injecting fine-FCC catalysts and coarse-glass beads in downers，were examined at different composition ratios of FCC catalysts to glass beads. Finally, based on the concept of dimensionless local particle velocities the new correlations for predicting the local particle velocity distributions of FCC catalysts and glass beads were developed by regressing experimental data from literatures and this study. Results show that the radial distributions of local particle velocities vary significantly with the particle properties, and for binary particle mixture, the radial distributions are more uniform as compared with those of only FCC catalysts and the double-peaked distribution characteristics of particle velocity profiles become more obvious with the increase of superficial gas velocities, since in this case fine particles mixed by injecting coarse particles will result in the variation of gas-solids dynamic mechanism and the smoothness of particle velocity distributions in dowers.

DEGRADATION KINETICS OF POLYCARBONATE IN SUPERCRITICAL METHANOL

CHEN Lei;WU Yongqiang;NI Yanhui;HUANG Ke;ZHU Zibin

2004, 55(11): 1787-1792.

Abstract ( 662 )

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Depolymerization of polycarbonate(PC) in supercritical methanol was studied to develop a chemical process for waste plastics recycling.Degradation experiments were carried out in a batch-type autoclave at 230—265 ℃,7.76—9.96 MPa without any catalyst.Reaction products were analyzed by infrared spectrometer(IR), size exclusion chromatography(SEC) and gas chromatography/mass spectrometer(GC/MS).The number average molecular mass (M_n) of around 27700 for the original PC decreased to 1600 at 245 ℃ within 15 min, meanwhile monomers of PC,dimethyl carbonate (DMC) and bisphenol (A), and byproducts yielded in supercritical methanol.Percent conversion of PC and the yield of monomers and byproducts were measured;and a mechanism of methanolysis was proposed in this paper.A mathematical model based on the continuous distribution kinetics for random degradation process and secondary reactions for monomer components can be used to interpret the results.The activity energy obtained was 75.72 kJ•mol^-1 for the random degradation.

KINETIC MODEL OF CATALYTIC CRACKING BASED ON OLEFIN REACTION MECHANISM

ZOU Shengwu, HOU Shuandi, LONG Jun, ZHOU Jian, SUN Tiedong, ZHANG Zhanzhu

2004, 55(11): 1793-1798.

Abstract ( 825 )

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A molecular kinetic model was derived on the basis of FCC reaction mechanism to represent the cracking reactions.Lumps were defined not only by their boiling range but also by their chemical compositions.A molecular lumped approach was then proposed for the FCC reaction in which H transfer,aromatization and yield of fuel gas were taken into account.In order to predict chemical composition of gasoline, eighteen kinetic parameters in the lumped reaction kinetic model were determined by the parameter estimation method.This work showed that the proposed model simulation results were coincident with the experiment data.The proposed model not only could predict successfully the yields,but also could provide more information of the chemical component of gasoline, which is useful in the study on how to reduce the olefins content of gasoline.

STRUCTURE OF La_2-xSr_xCoO_4±λ AND THEIR CATALYTIC PROPERTIES IN OXIDIZATION OF CO AND C₃H₈

YANG Xiaomao;LUO Laitao;ZHONG Hua

2004, 55(11): 1799-1802.

Abstract ( 544 )

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The perovskite-like La_2-xSr_xCoO_4±λ(x=0—1.0)mixed oxides were prepared by the polyglycol gel method, investigated by using the XRD, IR, BET, TPD and chemical analysis methods, and used successfully for CO and C₃H₈ oxidization.In addition, the effects of coefficient x on their structure and catalytic activities of these samples were studied.The results indicate that all La_2-xSr_xCoO_4-λhave K2NiF4 structure, their structure and catalytic activities change regularly with the change of coefficient x.The catalytic activity of LaSrCoO_4-λ is the best among all samples, which can be explained in terms of more mobile lattice oxygen, higher content of Co³⁺, more oxygen vacancies and more chemisorbed oxygen of LaSrCoO_4-λ.

SYNTHESIS AND CHARACTERIZATION OF SILICA-SUPPORTED PEG-400 Mo（Ⅵ）COMPLEX AND ITS CATALYTIC ACTIVITIES IN EPOXIDATION OF CYCLOHEXENE

ZHANG Yadong, WANG Zhenxing, CHEN Xia, JIANG Denggao

2004, 55(11): 1803-1808.

Abstract ( 736 )

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Polyethylene glycol-400（PEG-400）grafted in silica（SiO₂）support as macromolecule ligand was synthesized, and the structure of the ligand was characterized by IR spectroscopy.The complex of silica-supported PEG-400 and molybdenum(Ⅵ)dioxo(2,4-pentanedione)［shortened form,SiO₂-PEG-Mo(Ⅵ)］was for the first time synthesized and characterized by infrared spectroscopy.The possible structure of the complex was discussed.As a catalyst, SiO₂-PEG-Mo(Ⅵ)complex was used in epoxidation process of cyclohexene,and its catalytic activity and selectivity was also investigated.Experimental results showed that the complex possessed excellent activity and selectivity for epoxidation of cyclohexene.A new analysis method of the amount of Mo in the catalyst and the analysis of epoxycyclohexane by gas chromatography were set up.For n(t-BuOOH) = 0.1 mol,n(cyclohexene)∶n(t-BuOOH)=3.5∶1,the volume of solvent was about 10 ml, reaction temperature 80 ℃,reaction time 60 min，and the amount of SiO₂-PEG-Mo(Ⅵ)complex catalyst was 0.5 g.In this reaction condition, based on t-BuOOH,the yield of epoxycyclohexane was more than 99.2%,the purity of epoxycyclohexan was about 99.5% by GC analysis.The catalyst recycled for 3 times still possessed high catalytic activity and selectivity,and the yield of cyclohexene oxide approached 99% in the above-mentioned reaction condition.

ELECTROLYTIC HYDROGENATION OF ANTHRACENE

LIU Changjian;LI Debao;BAO Xiaojun

2004, 55(11): 1809-1814.

Abstract ( 634 )

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Electrochemical hydrogenation of anthracene was carried out in a divided three-electrode cell with spumous Pb as cathode and Pt as anode.The curves of current-potential and the effectiveness of hydrogenation in CH₃CN+EtOH+H₂O+Bu₄NBr,EtOH+H₂O+Bu₄NBr,DMF+H₂O+Bu₄NBr,and DMF+EtOH+H₂O+Bu₄NBr electrolysis systems were studied.It was shown that the CH3CN+EtOH+H2O+Bu4NBr system was suitable for electrochemical hydrogenation of anthracene,and the product was dihydroanthracene in these systems.Furthermore,the effects of constitutes of solvents, water content, supporting electrolyte, and temperature were investigated.The optimum conditions found are potential=-1.9V,［CH₃CN］/［EtOH］＝2/1(v/v)，［H₂O］＝5.5mol•L^-1,［Bu₄NBr］＝0.50mol•L^-1 and T=35℃.The yield of dihydroanthracene is 91.37% for six hours electrolysis in these conditions.

Bi-Si MESOPOROUS ZEOLITES（Ⅰ）SYNTHESIS，CHARACTERIZATION AND CATALYTIC ACTIVITY

CHEN Xiaohui;SU Jianfeng;WEI Kemei

2004, 55(11): 1815-1820.

Abstract ( 738 )

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Bi-Si mesoporous zeolites(Bi-Si)with different Si/Bi ratios were synthesized with the hydrothermal method which used TEOS as silica source, Bi(NO₃)₃•5H₂O as metal source, cetyltrimethylammonium bromide as template, and the oxidation of styrene by hydrogen peroxide to benzaldehyde catalyzed by the zeolite prepared was investigated.The nature of the catalysts was discussed based on the characterization results with nitrogen adsorption-desorption (BET), X-ray diffraction(XRD), scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet-visible spectroscopy(UV-Vis),and thermogravimetric method(TG).Bi-Si had high ordering structures of Mobile Crystalline Material-41 and bismuth was highly dispersed in the mesostructure framework.With increasing bismuth content, the crystallite of Bi-Si became disorderly,and at the same time the value of d₁₀₀ decreased.Bi-Si was found to be catalytically active in the oxidation of styrene to benzaldehyde with H₂O₂ as oxidant and methanol as solvent.The conversion of styrene increased with increasing Bi content,while the selectivity of benzaldehyde decreased.The catalyst with Si/Bi=22.5(mole ratio) showed higher catalytic activity,and the yield of benzaldehyde reached 14.1%.The influence of the ordering of mesostructure and the Bi content on the oxidation activity of Bi-Si was also discussed.

NUMERICAL SIMULATION AND EXPERIMENTAL STUDY ONSEPARATING PERFORMANCE IN SPIRAL SEPARATOR

ZHOU Guoyan;LING Xiang;TU Shandong

2004, 55(11): 1821-1826.

Abstract ( 749 )

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The Computational Fluid Dynamics(CFD)method was used to simulate the flow fields and calculate the separation efficiency of air-liquid spiral separators with different structural parameters.The RSM turbulent model (Reynolds Stress Model), which abandons the isotropic eddy-viscosity hypothesis, was used to analyze the highly swirling flow fields in spiral separators.Random Orbit Model was used to simulate the traces of liquid droplets in the whole flow field.Based on the simulation, the effects of helical pitch and screw number on the separating performance were studied, which was further tested and verified.The results showed that the Reynolds Stress Model predicted successfully the characteristics of the flow and the simulated performances were in good agreement with those obtained by tests.It should be feasible to design the spiral separators based on the method of Design by Numerical Analysis.

ROLE OF HOLDUP IN BATCH DISTILLATION

ZHANG Xuemei, ZHANG Weijiang, JIAN Chungui, ZHANG Junbao

2004, 55(11): 1827-1832.

Abstract ( 706 )

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Liquid holdup in batch distillation column affects the transfer of mass and heat and thus the whole dynamic response of the system.The role of column holdup on the performance of batch distillation has been studied by researchers in the past,but it is still the focus of debate because none of the studies is systematical.In this paper,the degree of difficulty of separation is proposed to correlate different parameters in batch distillation and the constant holdup model is built.The effect of holdup on batch distillation was studied systematically.It was found that condenser and reflux drum holdup was detrimental to the separation,but increasing column holdup might improve the performance in some cases.Further studies on the dynamic role of column holdup showed that the ratio of column holdup to initial charge acted as a factor.So an optimum initial charge existed for a column when the degree of difficulty of separation q＜0.7,which was checked and proved by experiments with toluene-ethyl benzene system.

ADSORPTION OF NITROBENZENE FROM AQUEOUS SOLUTION BY INORGANO-ORGANO-MONTMORILLONITES

REN Guangjun;ZHAI Yuchun;SONG Enjun;ZHANG Chunli;WANG Xin

2004, 55(11): 1833-1836.

Abstract ( 700 )

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Inorgano-organo- montmorillonites were obtained by using Keggin ion which prepared by reaction of Al³⁺and alkaline solution at the molar ratio of OH^-/Al³⁺=2.4.It was shown by XRD analysis that the dimension of the pillared interlayer montmorillonites obtained was increased to 1.9 nm and over.The adsorption of nitrobenzene on four modified montmorillonites was also studied and the results indicated that the adsorption capacities of inorgano-organo-montmorillonites were much better than Na-montmorillonites.The adsorption dynamics follows the laws of Bingham and Langmuir equation.The relation between adsorbtive capacity (q_e) and equilibrium concentration (C_e) fitted the isothermal adsorption equations of Freundlich and Langmuir.The adsorption could be interpreted as exothermic physical adsorption and organic compound partition.

PROCESS MONITORING AND FAULT DETECTION BASED ON BLIND SIGNAL PROCESSING WITH TEMPORAL STRUCTURE

CHEN Guojin;LIANG Jun;QIAN Jixin

2004, 55(11): 1837-1841.

Abstract ( 612 )

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A chemical process has usually a larger number of measured variables which are often driven by fewer unmeasurable latent variables (or sources).Extracting such latent variables and monitoring them will improve the process-monitoring performance.However, lots of existing process monitoring methods are based on the assumption that measured variables are subjected to independent and identical distribution (iid), which is not always valid in a chemical process.In this paper, an extended multivariate statistical control method based on independent component analysis with temporal structure is proposed to overcome the limitation of the assumption of iid.For investigating the application of this method to a continuous-stirred-tank-reactor process (CSTR),fault-detection performance was evaluated and compared with that of the conventional independent component analysis (CICA).The simulated results demonstrated the advantages (e.g. decreasing the number of false alarm and missed alarm) of ICA with temporal structure over the CICA approach under the assumption of iid, which is still widely used.

TRAIT IMPROVEMENT OF RIBOFLAVIN-PRODUCING Bacillus subtilis BY GENOME SHUFFLING AND METABOLIC FLUX ANALYSIS

CHEN Tao, WANG Jingyu, ZHOU Shiqi, CHEN Xun, BAN Rui , ZHAO Xueming

2004, 55(11): 1842-1848.

Abstract ( 771 )

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Traits of riboflavin-producing B.subtilis 24/pMX45 were improved by genome shuffling and DNA recombination.Riboflavin operon of B.subtilis 24 was integrated within chromosome of B.subtilis and was amplified to multi-copies,and B.subtilis RH33/pMX45 were obtained after two rounds of genome shuffling.The strain produced about 100% more riboflavin than the original strain B.subtilis 24/pMX45 in batch culture with 12% glucose as carbon source.In addition, the strain showed some promising traits such as quick assimilation of glucose, rapid growth, competence development and capablity of gene integration and amplification.Subsequently, the metabolic flux distribution in batch culture of three riboflavin-producing B.subtilis were compared and analyzed.The results of flux analysis and experiment indicate that the primary limiting factor for improvement of riboflavin production in B.subtilis RH33/pMX45 lies in the reactions between 5-P-ribulose and GTP.

ENZYMATIC HYDROLYSIS OF SOYBEAN STRAW AND L-LACTIC ACID FERMENTATION

XU Zhong;WANG Qunhui;JIANG Zhaohua

2004, 55(11): 1849-1852.

Abstract ( 894 )

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Soybean straw is an abundant,potential fermentation substrate.The most efficient means to produce fermentable sugars from soybean straw is enzymatic hydrolysis.For the sake of increasing the enzymatic hydrolysis of soybean straw and extracting the raw material for producing biodegradable plastic-lactic acid from soybean straw,enzymatic hydrolysis of soybean straw by cellulase was investigated.With initial soybean straw concentration of 5%,reducing sugar concentration and saccharification rate after enzymatic hydrolysis were 242.25 mg•g^-1 and 51.22% respectively.L-lactic acid production by Lactobacillus casei and Lactobacillus sake on cellulose and hemicellulose hydrolysate of ammonia pretreated soybean straw was also studied.7.52 g•L^-1 ,8.79 g•L^-1 and 11.07 g•L^-1 of lactic acid could be further obtained by fermentation with Lactobacillus casei and Lactobacillus sake and mix lactobacilluses.The lactic acid yields were 48.27%, 56.42% and 71.05% respectively based on glucose in hydrolysate.

MICROSTRUCTURE OF SELF-DESULFURIZATION RESIDUE OF HUANGLING COAL ASH IN COMBUSTION

CHENG Jun;ZHOU Junhu;LIU Jianzhong;XU Xiaoqiong;CAO Xinyu;CEN Kefa

2004, 55(11): 1853-1858.

Abstract ( 593 )

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The crystal phases, porosity and surface morphology of self-desulfurization residue of Huangling coal ash were studied by XRD, N₂absorption and SEM.It was found that the total content of sulfation product CaSO₄ and BaSO4 was 8.5% in the self-desulfurization residue obtained at 800 ℃, while that of active CaCO₃ and CaO was 4.9%.The residue surface was composed of many 7.5—15 μm particles that containd some 0.7—1.5 μm button-like particles and pores.However neither CaCO₃,CaO,CaSO₄ nor BaSO₄ were found in the residue obtained at 1200℃,due to thermal decomposition and intense melting.The residue surface was composed of some 30μm particles that containd 3—5 μm nonporous particles with smooth surface.There was a distinct decrease in porosity parameters of the residue when the furnace temperature increased from 800 ℃ to 1200 ℃.

DEGRADATION OF 2,4-DICHLOROPHOXYACETIC ACID BY OZONE WITH ULTRASOUND(Ⅰ)SYNERGISTIC EFFECT OF OZONATION AND SONOLYSIS

CHEN Lan;SHI Huixiang;WANG Dahui

2004, 55(11): 1859-1863.

Abstract ( 694 )

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The degradation of 2,4-dichlorophoxyacetic acid (2,4-D)by using ozonation alone（O₃） or ozonation combined with sonication(O₃/US)was studied.The results showed significant synergistic effect of ozone and ultrasound.•OH radical played an important role in the degradation of 2,4-D by the O₃/US technique.Under ultrasound irradiation,mechanical effects of ultrasonic energy enhanced the mass transfer of gaseous ozone to the liquid phase.The enhancement of ultrasound was mainly attributed to that ozone decomposition could be accelerated to produce abundant radicals by cavitation effect, which resulted in high temperatures and pressures during cavitation bubbles collapse.

DEGRADATION OF 2,4-DICHLOROPHOXYACETIC ACID BY OZONE WITH ULTRASOUND (Ⅱ)DEGRADATION PATHWAY

CHEN Lan;SHI Huixiang;WANG Dahui

2004, 55(11): 1864-1868.

Abstract ( 682 )

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The degradation of 2,4-dichlorophoxyacetic acid (2,4-D) by ozonation combined with sonication(O₃/US) was investigated.Based on the authors’ first paper about the synergistic effect of ozone and US, this paper presents intermediate products of 2,4-D degradation.The main intermediates were 2,4- dichlorophenol, benzopuinone, hydroquinone and organic acids,such as maleic acid and oxalic acid and so on.In various experimental conditions, concentrations of main intermediates and chloride ion in the solution were determined to analyze reaction pathways, and the degradation mechanism was discussed.

Sn CONTAINING CATALYST FOR PARTICULATE REMOVAL FROM DIESEL EXHAUST GASES

LIANG Hong;YE Daiqi;LIN Weiming;FU Mingli;HE Xiongbin

2004, 55(11): 1869-1873.

Abstract ( 628 )

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The catalytic oxidation traps seem to be one of the best ways for diesel particulate removal from exhaust gases thanks to their simplicity, easy handling, high abatement efficiency and comparatively low cost.The catalyst contained in such device should lower down soot ignition temperature to the values characteristic of diesel exhaust (180～350 ℃).This paper concerns the development of catalyst for catalytic oxidation traps.Sn catalyst was loaded on TiO₂ and γ-Al₂O₃-coated cordierite honeycomb and the catalysts were modified by Cu,K,V.The catalysts were activated in air in a muffle oven at 700℃ for 3 h.Catalyst activity was checked through DSC/TG experiments.Sn catalysts remarkably decreased soot ignition temperature and enlarge combustion temperature range.Along with adding Cu,K,V, the ignition temperature made further decrease and combustion temperature range narrowed slightly.The activation processes resulted in activity decrease.The reason for activity decrease was not caused by sintering,but by lapse of activity component.

CLEANER PROCESS OF NH₄OH-KOH PULPING OF WHEAT STRAW

HUANG Guolin;ZHANG Chengfang;ZOU Lixia;CHEN Zhongsheng

2004, 55(11): 1874-1877.

Abstract ( 710 )

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A cleaner process of wheat straw pulping with aqueous ammonia containing a small amount of caustic potash was studied.The caustic potash as a strong base not only could reduce the needed quantity of NH₃ used and cooking time, but also enriched black liquor with potassium element.The black liquor after recovering excess NH₃ contained nitrogen, potassium and organic substance and could be used as a fertilizer.The black liquor could be applied as liquid fertilizer directly,or the black liquor could be treated by coagulation in alkaline condition and the precipitate could be chemically modified to solid fertilizer.The clear liquid after precipitation could be recycled to cooking by adding NH₄OH and KOH.The environmental pollution of black liquor would be solved and a new pattern of virtuous cycle was set up between paper industry and farming.

“OVERSHOOT”PHENOMENON IN POLYMER DIFFUSIVE SYSTEM

LEI Hua;LU Yang;ZHOU Xiaoqin;PAN Qinmin

2004, 55(11): 1878-1883.

Abstract ( 646 )

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Non-Fickian diffusion is one of the important phenomena often observed in chemical processes, especially in polymer-related diffusion, and of which “overshoot” is interesting.The Jou model based on the EIT theory was used to study “overshoot” behavior observed in polymer diffusive system.After simplification of the Jou model,a diffusion dynamic equation, which was characterized with hyperbolic type, was obtained, then simulative analysis for three combined dimensionless parameters was done to research various diffusion behavior resulted from the change of model parameters.Results indicated that, the equation could describe “overshoot” phenomenon, so that the cause of “overshoot” could be interpreted theoretically/mathematically.The existence of the intrinsic relaxation time for diffusion was a necessary requirement, and with appropriate existence of diffusive retardance, that diffusion time greater than relaxation time was a sufficient requirement for “overshoot” behavior.

PREPARATION OF STRONG ACIDIC CATIONAL EXCHANGE FIBER

FENG Changgen;YANG Haiyan;ZENG Qingxuan

2004, 55(11): 1884-1888.

Abstract ( 700 )

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The strong acidic ion exchange fibers with higher exchange capacities up to 3.2 mmol•g^-1 were prepared by the dehydration reaction of polyvinyl alcohol(PVA)fiber followed by sulfonation.The paper studied the effects of dehydrating catalyst，temperature,and atmosphere on dehydration reaction and the effects of mass loss, temperature and time of sulfonation on exchange capacities.The IR spectra showed that the dehydrated fiber exhibited the absorption peak of carbon double bond.There were absorption peaks of S=O and C=S in the IR spectra of the product.The spectrogram of electron diffraction indicated that the fiber could keep its crystalloid structure by drawing tension.

LIQUID REYNOLDS STRESS IN LINEAR SHEAR BUBBLY FLOW WITH INTERMEDIATE REYNOLDS NUMBERS

XU Zhaofeng;LUO Rui ;YANG Xianyong

2004, 55(11): 1889-1893.

Abstract ( 757 )

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Analytical investigation of liquid Reynolds stress in shear bubbly flow with intermediate Reynolds numbers is absent.In this paper, the velocity field around a sphere bubble in linear shear liquid is assumed to be the linear superposition of the velocity field of uniform liquid passing a sphere bubble and the linear shear velocity field.The formula of shear liquid Reynolds stress was derived by averaging the velocity field in the cell-ensemble averaging method, and the formula was corrected under conditions of intermediate Reynolds number.The formula was compared with that of Sato, and the predicted results of local liquid velocity of the fully developed upward bubbly flow in pipes were compared with the experimental data.The results show that the formula is valid and accurate in prediction.

KINETICS OF p-XYLENE LIQUID PHASE CATALYTIC OXIDATION (Ⅳ)KINETICS FOR PX AND SOLVENT BURNING

CHENG Youwei;LI Xi ;SIMA Jian

2004, 55(11): 1894-1899.

Abstract ( 719 )

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Burning of p-xylene and solvent during oxidation is the critical side reaction.In this paper the burning mechanism is analyzed and the kinetics model is developed on the basis of the radical chains reaction mechanism.Model parameters were determined by data fitting of the CO_x transient response curves.The experimental results showed that, the CO_x generating rates increased remarkably with increasing Co/Mn ratio and catalyst concentration.As compared with the main reaction, the burning rate was more sensitive to the change of the ratio of cobalt vs manganese, but less to bromine concentration.

MECHANISM OF PHYSICAL ADSORPTION AND CHEMICAL ADSORPTION OF ETHYLENE

ZHANG Yongchun, ZHOU Jinxia , GUO Xinwen

2004, 55(11): 1900-1902.

Abstract ( 817 )

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An ab initio molecular orbital study connected with adsorption experiments was performed to determine the mechanism of physical adsorption and chemical adsorption of C₂H₄ on metals, and to compare the effects of the two kinds of adsorption.The results indicated that the adsorption styles were determined by whether there were local symmetry-adapted orbitals, whether the energy gap between symmetry-adapted orbitals was small and whether the electron occupancy of the symmetry-adapted orbitals was “occupancy vs. vacancy”.The different valence shells and orbital energies of Ag⁺ and Na⁺ resulted in different adsorption styles,chemical adsorption of C₂H₄ on Ag⁺ and physical adsorption of C₂H₄ on Na⁺ respectively.

MORPHOLOGY AND SIZE CONTROL OF DRUG-LOADED MICROSPHERE BY SPRAY DRYING METHOD

CHU Maoquan;LIU Guojie

2004, 55(11): 1903-1907.

Abstract ( 723 )

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Drug-loaded microspheres are usually used as a biophysically targeted delivery system.The morphology and size distribution of the microspheres are key effects on the efficiency in therapy.The microspheres could be prepared by the spray drying method, and the characterization could be controlled by varying the drying conditions.The whole preparation process is highly efficient, and suitable for commercialization.In this work,a case for preparation of the microspheres of tanshinone (TAN) solid dispersions was studied, and the mechanisms of morphology and size control of microspheres during the spray drying process were investigated.The effects of inlet temperature，concentration and components of precursors, and feed rate on the morphology and size distribution of products were studied.The results showed that the morphology of the dry products depended on the inlet temperature, the components of precursor and feed rate.Among them,temperature was the most important factor.The size of microspheres was mainly controlled by the concentration of the precursor.This work might be a reference for morphology and size control of targeted drug delivery microspheres by the spray drying method.

QUANTITATIVE EVALUATION OF BIOMASS-ADSORBENT INTERACTIONS IN EXPANDED BED——BIOMASS PULSE RESPONSE METHOD

ZHONG Lina, LIN Dongqiang, LV Miaohua, YAO Shanjing

2004, 55(11): 1908-1911.

Abstract ( 753 )

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The biomass pulse-response method was established and the biomass transmission index was introduced as a quantitative parameter for evaluating the biomass-adsorbent interactions in the expanded bed.With baker’s yeast intact cells and cell debris as the model biomass and anion exchanger Streamline DEAE as the model adsorbent, a series of factors were investigated to optimize the evaluation method.The appropriate operation conditions were chosen as the OD₆₀₀ of biomass pulse at the range of 0.5—0.6, and pulse loading at 80% volume of sedimented bed, expansion factor at 2.5.The method was then used to study the influence of ionic strength of fluid phase on the biomass-adsorbent interactions.The consistent results and slight measurement errors demonstrated that the biomass pulse-response method established in the present work is feasible, reliable and effective for quantitative evaluation of biomass-adsorbent interactions in the expanded bed.

CATALYTIC DECHLORINATION OF m-DCB IN WATER BY Pd/Fe

ZHOU Hongyi;XU Xinhua;WANG Dahui

2004, 55(11): 1912-1915.

Abstract ( 751 )

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Pd/Fe bimetallic catalysts were synthesized via chemical deposition and used to treat m-DCB.Batch experiments demonstrated that the Pd/Fe bimetallic particles could effectively dechlorinate m-DCB.The dechlorination efficiency reached 90% at a Pd/Fe loading ratio of 0.02% (mass) and metal to solution ratio 4g∶75ml in 90 min.Dechlorination was affected by several factors such as reaction temperature, pH, Pd/Fe ratio, and the induction of Pd/Fe catalysts.Chlorobenzene represents the partially stable dechlorinated intermediate in the generation of the final product (i.e., benzene), while part of m-DCB was dechlorinated to benzene directly.The dechlorination reaction was believed to take place mainly on the active surface sites of the Pd/Fe bimetallic particles via a pseudo-first order reaction, and the activation energy of this reaction was found to be 96.6 kJ•mol^-1.

THERMODYNAMICS ANALYSIS OF HYDROGEN PRODUCTION BY GLUCOSE GASIFICATION IN SUPERCRITICAL WATER

YAN Qiuhui;GUO Liejin;ZHANG Ximin;LV Youjun;LIANG Xing

2004, 55(11): 1916-1920.

Abstract ( 750 )

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The conversion of biomass into hydrogen-rich gas provides a competitive means for producing clean energy and chemicals from renewable resources.Based on the principle of Gibbs free energy minimization, a new method was presented with better effectiveness and simplicity to be used for the prediction of chemical equilibrium composition of hydrogen production by biomass gasification in supercritical water(SCW).Applying this method to analyzing the process of glucose gasification in SCW, it was found that the product gas consisted primarily of hydrogen and carbon dioxide as well as a small amount of methane and carbon monoxide.The gas yield was strongly affected by reaction temperature and feedstock concentration and less affected by reaction pressure in the following range:temperature 623—1073 K,pressure 22.5—35 MPa,and concentration 0.1—0.8 mol•L^-1.The hydrogen production in product gas increased with the increase of temperature and decreased with the increase of concentration.

NEW TECHNOLOGY FOR IMMOBILIZATION OF POLYPHENOL OXIDASE FROM TOBACCO

XIAO Hourong, ZHU Renfa, XU Xiaolong, XIE Yongshu, LIU Qingliang

2004, 55(11): 1921-1924.

Abstract ( 925 )

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Granule chitosan was prepared from chitosan,chemically-modified, then used as carrier and covalently linked with polyphenol oxidase(PPO) from tobacco by using glutaraldehyde as cross-linking agent.The desirable granule chitosan could be obtained when the molecular mass of chitosan was about 250000 and its concentration was about 30%.The absorbing ability and the category, distribution and number of active groups on the surface of granule chitosan were all improved by formol titration under weak basic condition after protecting parts of free amino-groups with Cu²⁺.The optimal conditions for immobilization of PPO were as follows: the ratio of PPO to granule chitosan: 0.8∶100(mass);concentration of glutaraldehyde:0.6%; immobilization time: 80 min.The resulting immobilized PPO had specific activity of 73 U•g^-1, and activity retention value of 83.2% was achieved.The K_m value of immobilized PPO was 4.67 mmol•L^-1 and that of soluble PPO was 1.26 mmol•L^-1.The optimal pH values were 6.0 for soluble PPO and 7.0 for immobilized PPO; the optimal temperature were 40 ℃ for soluble PPO and about 50 ℃ for immobilized PPO.In addition, stability of immobilized PPO to temperature and pH was obviously increased.

STATISTICAL ANALYSIS ON AUTHORS IN JOURNAL OF CHEMICAL INDUSTRY AND ENGINEERING（1998～2002）

FENG Xiangchun

2004, 55(11): 1925-1927.

Abstract ( 741 )

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Using the principle and the method of bibliometrics, Journal of Chemical Industry and Engineering (1998—2002)are classified, and the papers from the following aspects as : paper number, the degree of cooperation and the rate of cooperation, region distribution, fund subsidy, the prime authors are analyzed. Finally, the journal is evaluated objectively.