The Chinese Journal of Process Engineering

Effects of Internals on the Particle Behavior in a Rectangular Moving Bed with Gas Cross-flow

CHEN Yun-hua;ZHU Xue-dong;WU Yong-qiang;ZHI Zi-bin

. 2007, 7(4): 639-645.

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The effects of internals on particle behaviors were investigated in a rectangular moving bed with gas cross-flow by changing the position and size of internals. Experimental results show that the velocity of particles near upstream face is faster than that of particles near downstream face in the condition of gas cross-flow. And it is possible that particles move at the same velocity under a certain gas velocity if an internal is located in a suitable horizontal position. As compared with an apparatus without an internal, location of internal could suspend the formation of cavity and decrease cavity size while it reduces critical value of pinning. To describe the cavity size and critical condition of pinning, it is assumed that the particle layer was divided into two virtual channels, whose widths were decided by the horizontal position of the internal. Using different widths of the two virtual channels, mathematical models for cavity size and critical condition of pinning were established respectively. The model data agreed with the experimental results.

Experiment and Model of Wet Sludge Pellet Drying in a Bubbling Fluidized Bed

HOU Feng-yun;LU Qing-gang;NA Yong-jie;JIAO Wei-hong;HE Jun

. 2007, 7(4): 646-651.

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Drying characteristics of single municipal sludge pellet in a bubbling fluidized bed where river sand is taken as drying medium are studied for designing bubbling fluidized bed sludge dryers. The effects of drying conditions, such as bed temperature, size of sludge pellet and fluidization velocity, on drying rate are investigated. The results show that the bed temperature and size of sludge pellet affect the drying rates exponentially. The drying rate is larger with higher sludge moisture. When the bed is fluidized at the higher velocities, which are more than 2 times the minimum fluidization velocities, increasing of fluidization velocities (from 2 to 5 times fluidization velocities) can not affect the drying rate. Based on the experimental data, a semi-theoretical model of sludge drying in a bubbling fluidized bed is proposed. The research results can be reference for the design of bubbling fluidized bed sludge dryers.

Experimental Study on a New-type of Fan-shaped Spray Atomizer

ZHOU Jun-hu;ZHOU Lin-hua;YANG Wei-juan;LU Zhi-min;LIU Jian-zhong;CEN Ke-fa

. 2007, 7(4): 652-656.

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Based on the study and analysis of Y-shaped atomizers and their atomization mechanism, a new-type of fan-shaped spray atomizer is developed and experimentally studied. The flowrate, atomizing angle and Sauter mean diameter (SMD) in the center of spray under different air and liquid pressures, and the SMD spatial distribution of certain working conditions in transverse and axial directions are investigated. By fitting liquid flowrates with equation of Y-shaped atomizer, the values of coefficients suitable for fan-shaped atomizers are obtained, m=0.39, b=0.98. The atomizing angle a is approximately between 90o and 98o and varies within narrow limit. The droplet size distribution of spray in transverse direction is in a "W" shape, and in axial direction the SMD decreases gradually and becomes steady eventually.

Study on High Efficiency New Tray of 3D Round Valves

ZHOU San-ping;CHU Ya-zhi;CHEN Bing;FAN Yu-guang

. 2007, 7(4): 657-660.

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The structure design and feature of a new type of 3D round valves were analyzed particularly. In an experimental rectangular column of 1000 mm′350 mm, the compared experiments between two trays equipped with 3D round valves and F1 type valves respectively were performed by employing a typical model experimental system of water-air. In the experiments, hydraulic properties, such as tray pressure drop, entrainment rate and leakage rate, were measured, and mass transfer efficiency were determined through the method of oxygen-absorption. The experimental results demonstrate that under the same condition, compared with that of the tray equipped with F1 type valves, the tray efficiency of 3D round valve is improved by about 20%, and its entrainment rate is slightly lowered. In the range of application in industry, the tray pressure drop and leakage rate of 3D round valves are both lower than those of F1 type tray. Consequently, the 3D round valve is proven to be a better valve in terms of comprehensive technology.

Adsorption and Diffusion Behavior of n-Butane and Butene-1 on ZSM-5 Zeolite with Different Si/Al Ratios and Temperatures

WANG Fei;WANG Wen-chuan;HUANG Shi-ping;TENG Jia-wei;XIE Zai-ku

. 2007, 7(4): 661-667.

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Adsorption and diffusion behavior of C4 fractions (n-butane and butene-1) on special shape-selective and acidic ZSM-5 zeolite with different Si/Al ratios, which is used as catalyst in olefins catalytic cracking (OCC) technology, was investigated using an intelligent gravimetric analysis apparatus (IGA-003, HIDEN) at 275, 288 and 300 K. The double Langmuir model was applied to simulate the adsorption of n-butane and butene-1 on ZSM-5 zeolite samples. The diffusion coefficients of n-butane and butene-1 were correlated in terms of the Fick diffusion model. The results indicate that the diffusion of n-butane and butene-1on ZSM-5 zeolites are intracrystalline diffusion, and the diffusion coefficients are of the order of magnitude 10-14 m2/s. In addition, the diffusion coefficients of n-butane are larger than those of butene-1 on ZSM-5 zeolites at the same temperature and pressure. Moreover, the diffusion coefficients of n-butane and butene-1 on ZSM-5 zeolites all increase with temperature, and increase with pressure first and decrease at high pressure. In addition, the diffusion coefficients of n-butane all increase with the Si/Al ratio. The results are applicable in the C4 olefins catalytic cracking technology.

Adsorption and Photocatalytic Degradation of Azo Dyes with Different Structures on the Surface of TiO2 Nano-particles

DONG Yong-chun;WANG Qiu-fang;DUN Mi-na;ZHU hong-xing

. 2007, 7(4): 668-673.

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Four water-soluble azo dyes widely used for the dyeing and printing of fabrics including Reactive Red MS, Reactive Blue B, Mordant Black PV and Acid Orange 156 were selected to study the adsorption and photodegradation of water-soluble azo dyes with different structures on TiO2 particulate photocatalyst in water. And adsorption behavior and modes of these dyes on the surface of TiO2 particles were investigated under various pH levels and in the presence of sodium chloride, respectively. The adsorption parameters of the dyes were obtained using experimental data fitting method. In addition, these azo dyes were degraded photocatalytically in the presence of TiO2 photocatalyst under varied pH levels in water. The results indicated that high pH values caused low adsorption quantity of the dyes on TiO2 particles, and their adsorption decreased significantly with the pH range from 4 to 8. Moreover, the amounts of four dyes adsorbed on TiO2 particles were increased in the presence of sodium chloride, and those of the two acid dyes were much higher than the two reactive dyes in terms of the amounts adsorbed on TiO2 under the same conditions. In addition, the adsorption isotherms of four dyes were described well by Langmuir adsorption model, and the reactive dyes showed higher adsorption constants and coverage on the surface of TiO2 particles than the acid dyes. On the other hand, increasing pH values reduced the photocatalytic decoloration percentages and first order reaction rate constants, and the reactive dyes were decomposed more easily than the acid dyes under the same conditions.

Extraction of Co2+ and Cd2+ from Wastewater Using Hydrophobic Ionic Liquids as Solvents

LI Chang-ping;XIN Bao-ping;XU Wen-guo;ZHU Qing-rong;LU Shi-xiang

. 2007, 7(4): 674-678.

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Extraction of Co2+ and Cd2+ into hydrophobic ionic liquids of [Bmim]PF6, [Hmim]PF6 and [Omim]PF6 is investigated for examining their removal from wastewater. The results indicate that the extraction rates of both Co2+ and Cd2+ are very low without chelator. However, the extraction rates are greatly enhanced from 2.06% to 96.37% for Co2+ and 1.82% to 93.68% for Cd2+ after the addition of chelator. The addition of different chelators also has a certain impact on the removal rates of heavy metal ions. The longer carbon bond the ionic liquids have, the better the extraction is. Similar to traditional solvent n-butanol, pH has a great impact on the removal rates of Co2+ and Cd2+. When pH<2, the extraction rates of Co2+ and Cd2+ are close to zero. While for pH>6, the extraction rates are above 90%. The pH swing effect is used to strip the heavy metal ions from ionic liquids, and the reuse of ionic liquids is realized.

Removal of Trace Cu2+ from Aqueous Solution by Foam Fractionation

LI Qian;WU Zhao-liang;ZHAO Yan-li;LIU Gui-min;WANG Lin

. 2007, 7(4): 679-683.

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Removal of Cu2+ from simulated aqueous solution by foam fractionation was studied using C18H30SO3 as the surfactant, especially the effects of pH, gas flow rate, surfactant dosage and volume of the solution were examined. The experimental results showed that C18H30SO3 had good foam performance and removed Cu2+ effectively from aqueous solutions by foam fractionation. Enrichment ratio reached 18.2, and removal rate 96.1% under the optimized conditions. Comparing C18H30SO3 with the commonly used surfactant, sodium dodecyl sulfate, this technology would not leave Na+ in the aqueous solutions, thus a new idea was put forward for removing ions or salts by foam fractionation.

Pervaporation Removal of Benzene from Aqueous Solution through Montmorillonite-filled Polydimethysiloxane Membrane

WANG Kang;YU Jiang;LIU Hui-zhou

. 2007, 7(4): 684-688.

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The preferential permeation of benzene over water was investigated with organo-modified montmorillonite-filled polydimethylsiloxane (PDMS) pervaporation membrane. The membrane was characterized by SEM and mechanical strength measurement. The results showed that incorporation of organo-montmorillonite enhanced the mechanical stress of membrane and improved its pervaporation properties. With the organo-montmorillonite content increasing, permeation flux increased, but the separation factor increased first and then decreased, reached to the maximum value when the organo-montmorillonite content was 9.09%. With operation temperature increasing, permeation flux increased, but separation factor decreased. With benzene concentration in feed solution increasing, permeation flux of benzene increased, while the water flux was kept unchanged, and the separation factor decreased. When the filler content was 9.09%, benzene concentration in feed solution was 1000 kg/kg, the permeation flux reached to 115 g/(m2×h), and the separation factor reached to 798, increased 12% and 32% respectively, compared with pure PDMS membrane.

Synthesis of Chelating Resin PETU and Its Adsorption to Ag(I)

ZHONG Hong;WANG Shuai;QIU Yun-ren;WANG Ai-ping

. 2007, 7(4): 689-693.

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A novel chelating resin (PETU) with thiourea groups in its main chain was synthesized by the reaction of O,O'-butane-1,4-diyl dicarbonisothiocyanatidate and triethylene tetraamine. The adsorption of Ag(I) on PETU was investigated by batch tests. The results showed that adsorption data fitted Boyd's diffusion equation of liquid film and the adsorption was controlled by liquid film diffusion. Under the temperatures between 15~60℃, the adsorption capacity decreased with the increase of temperature, and increased with the increase of initial concentration of Ag(I). The experimental data fitted Langmuir and Freundlich equations, and the correlation coefficients for Langmuir equation were between 0.9965~0.9998, and those for Freundlich equation were between 0.8211~0.9810, and increased with the adsorption temperature. DH, DG and DS calculated by thermodynamic formulae were all negative, which meant that the adsorption process was exothermic and spontaneous, and the entropy decreased during the process. XPS results showed that N, S and O atoms were the electron donors to coordinate with Ag.

Macrokinetics of Catalytic Synthesis of Propylene Glycol Monomethyl Ether Propionate

TANG Ji-hai;DAI Bin;QIAO Xu;CUI Mi-fen

. 2007, 7(4): 694-697.

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Propylene glycol monomethyl ether propionate (PMP) was synthesized from propylene glycol monomethyl ether and propionic acid over macroporous strong acid ion exchange resin, and the pseudo-homogeneous second-order reaction kinetic model was developed. The kinetic data of this system were measured at boiling temperature of the reaction system in a batch reactor. The concentration of PMP as function of reaction time was established by solving macrokinetic model using Gear algorithm, then the squared sum of differences between calculated values and experimental data of concentration of PMP was minimized by nonlinear least square regression using Levenberg-Marquardt algorithm, and the activation energy was obtained, being 80.12 and 89.49 kJ/mol for the positive and reverse reactions, respectively. The data calculated from the model were in good agreement with experimental results, and the results of residual analysis showed that the model was reliable.

Effect of CO2 on Activation of Limestone Used as Desulfurization Sorbent

ZHANG Li;JIN Ling;LU Ji-chang;LIU Yun-yi

. 2007, 7(4): 698-701.

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The effect of CO2 gas on activation of limestone used for removal of SO2 from flue gas was experimentally studied in a bubbling bed reactor in batch operation. Based on variation of pH value with the desulfurization time, the mechanism of SO2 reacting with limestone activated by CO2 was also investigated. The experimental results show that high desulfurization efficiency and sorbent utilization ratio relative to high dissolution rate of limestone in water solution could be obtained by long time contact with CO2 gas. And the effect of CO2 gas on activation of limestone was confirmed by the experimental results from continuous operation with a fluidized bed as reactor. Accordingly, a new process to improve activity of limestone in the reaction with SO2 has been developed, which may find industrial application in a flue gas desulfrization process with limestone slurry as desulfurization sorbent.

Carbonchlorination Reaction of Ludwigite

WANG Xiao-huan;ZHANG Li-qing;HOU Ming-yan;WANG Ting;ZHOU Hua-feng

. 2007, 7(4): 702-705.

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The feasibility of ludwigite carbonchlorination process and its requisite thermodynamic conditions were analyzed with thermodynamics. The compounds contained in the ludwigite follow a thermodynamic carbonchlorination ability order of 2MgO×B2O3> MgO>Fe2O3>Mg2SiO4>SiO2. According to the different physical and chemical characters of chlorination products, the separation of main elements, boron, magnesium and iron in ludwigite was realized preliminarily. In this study, the influential factors of reaction temperature and time on ludwigite chlorination rate were examined. Ludwigite carbonchlorination process was investigated in the temperature range from 550℃ to 750℃, the highest chlorination rate was 94.02% at 700℃ for 90 min. The insoluble residue was determined with XRD diffractometer. The residue obtained at 700℃ for 90 min contained mainly a certain amount of unconverted Mg2SiO4.

Experimental Studies on Quick Reduction of Fine Iron Ore with Hydrogen at Low Temperatures

WANG Dao-jing;CHEN Hua;LI Qiu-ju;HONG Xin

. 2007, 7(4): 706-711.

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Based on the research work previously, a new technology of continuous prereduction of fine iron ore with hydrogen at low temperatures (180~570℃) and low pressure (<0.2 MPa) was introduced, and its feasibility was also studied by experiments in this work. The effects of reaction temperature, particle size, ratio of solid to gas and reaction time on the reduction rate of fine iron ore were examined respectively. The experimental result showed that a reduction rate of 39.2% was achieved while the fine iron ore with averaged particle size of 61.7 mm was heated up to 570℃ and remained for 40 s in the reactor with a ratio of solid to gas of 0.22 g/L. XRD analysis of the reduction product indicated that Fe2O3 was reduced into Fe3O4 and Fe.

Preparation and Photocatalytic Performance of TiO2-coated Natural Zeolite in Degradation of Papermaking Wastewater

YAO Shu-hua;HUA Li;SHI Zhong-liang

. 2007, 7(4): 712-717.

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Using Ti(OC4H9)4 and C2H5OH as reaction raw materials, the photocatalyst of TiO2-coated natural zeolite was prepared by sol-gel method. The experimental techniques of XRD and SEM were used to characterize the prepared TiO2-coated photocatalyst. The influences of components of sol-gel system, calcination temperature and time, amount of catalyst, radiation time and pH value on the photocatalytic degradation of papermaking wastewater on the TiO2 coated natural zeolite were studied. The optimal experimental conditions were obtained: the volume ratios of C2H5OH to TiO(C4H9)4 4.0, CH3COOH to TiO(C4H9)4 0.1, H2O to TiO(C4H9)4 0.15 and HNO3 to TiO(C4H9)4 0.1, calcination temperature 300℃, calcination time 4.0 h, amount of catalyst 50 g/L, pH value of papermaking wastewater 4.0, and radiation time 8.0 h, the COD removal rate of papermaking wastewater reached 81.93% under the conditions. The experimental results show that TiO2-coated natural zeolite has a good photocatalytic activity to degrade papermaking wastewater.

Treatment of Drilling Wastewater Correlated with Three-sulfonated Mud System by Coagulation-Ozone Oxidation Process

ZHANG Hong-yan;LU Rong-hu;GUO Shao-hui

. 2007, 7(4): 718-722.

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The chemical oxygen demand (COD) value of effluent of drilling wastewater correlated with three-sulfonated mud system after coagulation was about 350~600 mg/L, and the residual organic substance in effluent after coagulation was discussed. The COD removal rate on coagulation was 77.2% with 6000 mg/L lime and 2000 mg/L ferrous sulfate and 81.2% by ozone oxidation at pH 12.5 and 5 min. The COD removal rate increased with the increase of pH, and ozone index (OI) increased with the decrease of COD value. The total COD removal rate after coagulation and ozone oxidation was 95.7%. The effluent purified was colorless and its COD value was less than 100 mg/L, which reaches the wastewater discharge standard.

Experimental Study on the Effect of Temperature Cooling Profile on Methane Hydrate Formation

LI Gang;LI Xiao-sen;Tang Liang-guang;FENG Zi-ping;FAN Shuan-shi;ZHANG Yu

. 2007, 7(4): 723-727.

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The methane hydrate was formed in an experimental vessel under two temperature cooling profiles, i.e. slowly and rapidly decreasing the temperature. The results show that the methane hydrate forming process consists of four stages with the two cooling profiles, gas/water dissolution, nucleation, growth and stable states. The temperature profiles have no obvious effect on the thermodynamic equilibrium of hydrate formation. However, they have a great effect on the hydrate growth kinetic process. Comparing the two cooling profiles under the same initial conditions, the methane hydrate growth rate was remarkably faster in the rapid cooling case than that in the slow cooling case, resulting in about 21.4%~28.8% reduction of hydrate growth time, depending on the initial forming conditions.

Effect of Ultrasound on Anti-solvent Crystallization Process of Glycin

ZHOU Tian;QIAN Gang;ZHOU Xing-gui;YUAN Wei-kang

. 2007, 7(4): 728-732.

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Crystallization of aqueous glycin solution with acetone as the anti-solvent is studied to examine the effects of ultrasound on crystal size and habit. With ultrasound excitations, the solution experiences cavitation, first nucleation, second nucleation, crystal growth, fragmentation, etc. Introducing ultrasound at different times or for different durations will have different influences on the crystallization distribution. If ultrasound is introduced for a short time before the onset of homogeneous nucleation to induce nucleation, one will obtain larger crystals, whereas if the ultrasound is introduced at or after the onset of homogeneous nucleation, smaller crystals will be obtained. If ultrasound is used in the growth stage, the crystals will also be small because the crystals will be fragmented by ultrasound.

CONE Measurement and Thermal Degradation of ABS Treated with CuO Microcapsules

LI Gui-fen;FANG Kun

. 2007, 7(4): 733-737.

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Thermal behavior and flame retardance of acrylonitrile-butadiene-styrene (ABS) containing CuO microcapsules were determined by TG, DTG and CONE measurements. Activation energy for the degradation of samples was obtained using the Broido method. The results show that for the degradation of ABS containing CuO microcapsules, heat, smoke, CO and CO2 releases are decreased, which indicates that the CuO microcapsules have good flame retardance and smoke suppression effects on ABS. The activation energy of ABS containing CuO microcapsules for thermal decomposition is increased by 21 kJ/mol, which shows that the CuO microcapsules increase the stability of ABS and make its decomposition more difficult. Simultaneously, the char yield is increased by 27.2%, which shows that the CuO microcapsules catalyze carbonization of ABS and decrease flammable gas in the decomposition of ABS.

Thermal Analysis and Kinetics of Larch Treated by Phosphorus-Amine-Formaldehyde Flame Retardants

GAO Ming;LI Gui-fen;YANG Rong-jie

. 2007, 7(4): 738-742.

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Larch was treated with phosphorus-amine-formaldehyde flame retardants. The thermal degradation of the treated larch samples was studied by thermal analysis and cone calorimeter. The flame retardant properties were characterized in limiting oxygen index, char yield, heat release rate and total heat release. Kinetic parameters of thermal degradation were obtained following the method of Broido. The limiting oxygen index and char yield increased while the heat release rate and total heat release decreased, which shows that combustibility of larch has largely decreased. For the degradation of the larch treated with flame retardants, the activation energy was greatly decreased, which shows that the flame retardants catalyze the dehydration and decomposition of larch. The main decomposition of larch occurred at lower temperatures (<300℃) through the reaction which includes dehydration, rearrangement, carbonization, evolution of carbon monoxide and carbon dioxide, and ultimately a carbonaceous residue, resulting in the formation of less flammable products and correspondingly more char, leading to low combustibility.

Process Intensification and Characterization of Agarose Gel Activation with Epichlorohydrin

SHI Qing-hong;PENG Guan-ying;SUN Shu;SUN Yan

. 2007, 7(4): 743-746.

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The epoxy density of agarose gels is generally limited by low water-solubility of epichlorohydrin (ECH) and its hydrolysis during the activation process. In this work, a hydrophilic organic agent, dimethyl sulfoxide (DMSO), was introduced to enhance the epoxy activation of agarose gel. The results showed that the phase interface of epichlorohydrin and agarose gel suspension was diminished in the DMSO solution. Thus the epoxy activation was enhanced by a high ECH solubility in DMSO. An optimal epoxy density over 100 mmol/mL was achieved at 10%(j) epichlorohydrin and 0.8 mol/L sodium hydroxide. The activated gel did not show any loss in performance. The coupling density of a ligand, 5-aminoindole, on the gel reached 95.3 mmol/mL, being 75% higher than that obtained with common epoxy-activated agarose gel. It exhibited intriguing potential in the preparation of functional agarose gel with a high density of ligand.

Pretreatment Technology of Biomass Entrained Flow Gasification

ZHANG Wei-wei;ZENG Guo-yong;CHEN Xue-li;YU Zun-hong

. 2007, 7(4): 747-750.

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Slow pyrolysis as the pretreatment technology before biomass entrained flow gasification was experimentally studied, and its feasibility assessed. The chemical composition and conveying characters of semi-char produced in the pretreatment were analyzed. At the same time, the entrained flow gasification results of biomass and semi-char were compared based on ASPEN PLUS software. The results show that the energy density of semi-char increases with the pyrolysis temperature. The mass and energy yields of semi-char are beneficial to the biomass entrained flow gasification with the pyrolysis temperatures between 300 and 400℃. The angle of internal friction and angle of repose decrease obviously with increasing the pyrolysis temperature. And the bulk density of semi-char is improved evidently with increasing the pyrolysis temperature. Based on the analysis with ASPEN PLUS, the entrained flow gasification result is most ideal when the pyrolysis temperature is 400℃.

Preparation of Precipitated Silica from Oil Shale Residue

LI Yong;XUE Xiang-xin;FENG Zong-yu;JIANG Tao

. 2007, 7(4): 751-754.

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Oil shale residue as a raw material of producing precipitated silica was firstly calcined for 4 h at 950℃ and treated by NaOH solution with 3.30 mol/L for 4 h, and then acidified by HCl until the pH value of solution was up to 8~9, the leaching rate of SiO2 in the residue reached 75.8%. The SiO2 purity in the precipitated silica product was 91.8% by X-ray fluorescence analysis. The chemical structure of precipitated silica was hydrated silicon oxide through FT-IR analysis. The structure of precipitated silica was amorphous by XRD analysis. The TEM micrograph showed that the shape of precipitated silica particles was nearly spherical, and the average grain diameter was less than 50 nm. The specific surface area of precipitated silica was 114 m2/g, pH was 5.5~6.0, heating loss was 5.82%, loss on ignition at 1000℃ was 6.16%. The product could be comparable with the requirements of HG/T 3061-1999 industrial product standard.

Computer Aided Solvent Design by Dynamic Method for Extractive Distillation Separation of Cyclohexane-Benzene Mixture

ZHAO Yue-qiang;WU Zheng-ming;LIU Wei-wei;TANG Li-juan;ZONG Jian;WANG Jin-xia

. 2007, 7(4): 755-760.

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The more rigorous 'dynamic method' instead of 'static method' based on UNIFAC model (modified UNIFAC model) was used to develop a program with FORTRAN language, which can be used to select solvent for extractive distillation separation of azeotropic and close-boiling mixtures and predict multi-component vapor-liquid equilibria (VLE). Verified by the VLE experimental data of ethanol-water system in the literature, this program gives the average relative deviation between the calculated gas phase equilibrium composition and that of literature 3.26% and 1.74% for UNIFAC model and modified UNIFAC model respectively, which manifests the reliability of this program. The extractive solvents to separate cyclohexane-benzene mixture were screened with high-throughput quantitatively by 'dynamic method' based on modified UNIFAC model, and the better solvents were determined based on the prediction results and feasible solvent selection principle as dichloromethane and 1,2,3-trichloropropane. The VLE data of cyclohexane- benzene-dichloromethane system at 101.325 kPa were measured through experiment, and the calculated VLE data of the systems fit well with experimental data. Dichloromethane as extractive solvent has the advantages of low energy consumption and fine heat stability of the separation system.

Refolding of Recombinant Snake Venoms Fibrino(geno)lytic Emzyme Fibrolase

ZHANG Shou-tao;SHI Jing;GUO Ai-guang

. 2007, 7(4): 761-766.

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Fibrolase is a non-hemorrhagic zinc metalloproteinase isolated from southern copperhead snake venom (Agkistrodon contortrix contortrix) and capable of degrading fibrin clots through specific cleavage of the Aα-chains of fibrin(ogen) at the position Lys413?Leu414. The DNA encoding of fibrolase was amplified by PCR and cloned into the pET25b(+) vectors and high-level expression in E. coli BL21(DE3) as inclusion bodies, the recombinant fibrolase was about 40% of the total cell proteins. Compared with the simple batch dilution refolding method, fed-batch dilution refolding and dialysis refolding methods are more efficient in this work for fibrolase refolding. At the same time, the experimental conditions, including temperature, pH, denatured protein concentration, GSSG concentration and GdmCl concentration in the renaturation process of recombinant fibrolase inclusion body were studied. Good results are obtained when refolding of fibrolase was carried out by fed-batch dilution refolding method at pH 8.5, 4℃, and refolding buffer consisted of 1.5 mol/L GdmCl, 1 mmo1/L GSSG and 2 mmo1/L GSH, and sample concentration is 10 mg/mL, dilution factor is 50. The recovery rate of recombinant fibrolase was about 25% after refolding and purification.

Adsorption and Separation of Lactic Acid and Glutamic Acid by Macroporous Resin Adsorbents

YANG Peng-bo;ZHANG Xiao-yan;CONG Wei;WANG Fang;DENG Li

. 2007, 7(4): 767-772.

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The macroporous resin adsorbent NKA-II was selected to separate lactic acid from the residual solution of fermentation. Adsorption behavior and selectivity of NKA-II were studied by using static and dynamic adsorption methods, including the static equilibrium adsorption and adsorption thermodynamic properties. The results showed that the adsorbent selectivity coefficient (KGL) of lactic acid and glutamic acid equaled to 16.19. The adsorption data were correlated with Freundlich isotherm equation, and the correlative coefficients (R2) all exceeded 0.99 at 26 and 48℃. Characteristic parameter of this equation n>1. Besides, the kinetics of adsorption of NKA-II was mainly controlled by intra-particle diffusion, and it fit well into the Kannan-Sundaram intra-particle diffusion model. The intra-particle diffusion rate coefficient kp was 6.0129 mg×min0.5/g. Dynamic adsorption results showed that the breakthrough volume of L-lactic acid was 140.6 mL, being 110.6 mL over the breakthrough volume of glutamic acid. So macroporous adsorbent NKA-II could be employed as the sorbent to separate lactic acid and glutamic acid.

Investigation of Immobilized Lipase onto Macroporous Carrier

CAI Hong-ju;FU da-yan;WANG Man-yi;ZHOU Xin;TAN Tian-wei

. 2007, 7(4): 773-777.

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Immobilization of lipase on macroporous poly(glycidyl methacrylate-co-divinylbenzene) was investigated and followed by the optimization of immobilizing conditions. The optimized results were achieved with the 1:1 mass ratio of lipase to the carrier, coupling temperature between 20~25℃, and immobilizing time of 1.5 h. The optimum pH and temperature of immobilized lipase were 8.5 and 40℃, respectively. The activity of immobilized lipase remained 94% of the origin after storage at 4℃ for 7 d. The experimental results showed that the thermal stability and operational stability were improved in comparison with free lipase.

Extraction of Xanthoceras sorbifolia Bunge Oil with Hydrolysis Enzymes

LIU Miao-miao;WANG Xiao-dong;ZHAO Bing;WANG Yu-chun

. 2007, 7(4): 778-781.

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Three commercial enzymes were used for extraction of oil from Xanthoceras sorbifolia Bunge seeds. The results showed that Alcalase 2.4 L was the most effective hydrolysis enzyme. The main factors influencing the oil extraction rate and degree of protein hydrolysis were analyzed by response surface methodology. Under the fixed ratio of enzyme to seeds (0.02 mL/g), the optimal parameters were temperature 55℃, pH=9, the ratio of solid to water 1:6 (g/mL), and enzyme incubation time 4 h. Under these conditions, the oil extraction rate and degree of protein hydrolysis reached 78.67% and 9.15% respectively.

Effects of Light Quality on Maca Callus Growth and Differentiation

WANG Ya-li;WANG Xiao-dong;ZHAO Bing;WANG Yu-chun

. 2007, 7(4): 782-785.

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The effects of light quality on maca (Lepidium meyenii) callus growth, differentiation and the key enzymes in glycolysis were investigated. Cultured for 25 d under red light, yellow light and white light, the dry weights of maca callus were heavier than those under green light and blue light. The induction rates of maca callus cultured on the differentiation culture media under red light, yellow light and white light were 78%~82%. However the induction rate was zero under green light and blue light. The activities of three key enzymes in glycolysis such as glucose-6-phosphate dehydrogenase (G-6-PDH), hexokinase (HK) and malate dehydrogenase (MDH) under red light, yellow light and white light were significantly higher than those under green light and blue light. The changes of enzyme activity were associated with the states of growth and differentiation of maca callus. The results showed that the glycolysis in maca callus was regulated by light quality and took part in regulating callus growth and differentiation.

Temperature Controlling Strategy for Alkaline Poly-galacturonate Lyase Production with Bacillus sp.

LIU Hui-juan;HUA Zhao-zhe;DU Guo-cheng;LIU Li-ming;CHEN Jian

. 2007, 7(4): 786-789.

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To enhance the yield and the productivity of alkaline poly-galacturonate lyase by Bacillus sp., the kinetic parameters of batch fermentation at different temperatures ranging from 32 to 41℃ were investigated. It was found that the consumption capacity of carbon source increased and the lag stage of cell growth could be shortened with controlling at a higher temperature (41℃). On the other hand, at the lower temperature such as 35℃, the production capability and rate of alkaline poly-galacturonate lyase were promoted. Based on the kinetic parameter analysis, a two-stage temperature controlling strategy, in which temperature was controlled at 41℃ in the first 4 h and then shifted to 35℃, was suggested and experimentally verified. Following this strategy, the following results were obtained by comparison with that of constant temperature 35℃, the maximum alkaline poly-galacturonate lyase activity was 53.0 U/mL, increased by 23.5%, the time of the maximum alkaline poly-galacturonate lyase activity observed was shortened to 16 h, and the productivity was 3315 U/(h×L), enhanced by 39.1%.

Preparation and Characterization of in-situ Nano Calcium Carbonate/Polystyrene Composite

WENG Sheng-guang;CHEN Jian-ding;XIA Zhe-an;ZHANG Sheng-miao;WU Qiu-fang

. 2007, 7(4): 790-795.

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CaCO3 nano-particles transferred from water phase into ethanol were treated by methacrylic acid to form reactive interface by ionic bonding. Well dispersed CaCO3 nano-particles in styrene obtained from the filtermass of treated CaCO3 nano-particles with solids content more than 80% at a temperature slightly higher than 100℃ were polymerized via in-situ bulk polymerization to produce nano-CaCO3/polystyrene composite. TEM images show that CaCO3 nano-particles with the sizes less than 100 nm were distributed homogeneously in polymer matrix. CaCO3 nano-particles can play a positive role to increase the toughness of composite material matrix, and the toughness of the composite with 7%~8% CaCO3 nano-particles can be improved up to 258% of pure polystyrene. The structure model of pool dispersion was proposed and used to explain the relationship between toughness and structure of the composite.

Stability of Carbon Black Dispersion for Gel Ink

FENG Zheng-yu;CHEN Ai-ping;QIAN Jun;PU Yu;LIU Wei

. 2007, 7(4): 796-801.

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Different kinds of dispersants were tested and the carbon black dispersion for gel ink was prepared. In order to characterize the stability of carbon black dispersion, a centrifugal separation-absorption spectrophotometry method was proposed and verified experimentally. The dosage of the dispersant was optimized. The effect of sand milling time on the storage stability of dispersion was investigated. The results indicated that the block copolymer with aromatic rings was the good dispersant for carbon black aqueous dispersion. The good storage stability of dispersion was achieved under the condition of 2 h sand milling by adding 20%(w) of ammonium solution of styrene-maleic anhydride resin based on the dry weight of carbon black. The mean particle diameter of the fresh dispersion was 117.1 nm and became 160.0 nm after 15 d storage. And the gel ink prepared with this dispersion also showed good storage stability and writing properties.

Preparation of Azithromycin Ultrafine Particles with Reactive Precipitation

WANG Guo-lian;WANG Jie-xin;SHEN Zhi-gang;GUO Fen;CHEN Jian-feng;Jimmy Yun

. 2007, 7(4): 802-806.

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Amorphous ultra-fine azithromycin (AZM) powder was prepared by a reactive precipitation method. The effects of the operation parameters, such as concentration of NaOH solution, stirring speed and time, and reaction temperature on the particle size, morphology, dispersion and yield of the products were experimentally investigated. The as-prepared particles were characterized by SEM, BET, XRD and FT-IR techniques. The dissolution rates of the ultra-fine products and commercial crude drug were also tested. The results indicated that ultra-fine AZM with a mean particle size of 413 nm could be obtained. The BET specific surface area of the micronized AZM product was about 27 times as much as that of the commercial crude drug. Furthermore, the as-prepared AZM ultra-fine particles exhibited a significantly enhanced dissolution property, compared with the raw materials.

CuO-CeO2/AC Adsorption Catalyst for Catalytic Dry Oxidation of Adsorbed Phenol at Low Temperatures

LEI Zhi-ping;LIU Zhen-yu;LI Bing-zheng

. 2007, 7(4): 807-811.

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An activated carbon (AC) supported copper and cerium oxide adsorption catalyst (CuO-CeO2/AC) was studied for catalytic dry oxidation of adsorbed phenol at low temperatures. The results show that the addition of CeO2 to CuO/AC significantly promotes its catalytic activity for phenol oxidation. The initial oxidation temperature of the adsorbed phenol is lowered by 30℃, the phenol adsorption capacity is increased by about 6%, the desorption of phenol in oxidation is reduced by about 77% and the residues formed in the oxidation are reduced. The effect of CeO2 on the process would be attributed to its oxygen that can be used for oxidation of phenol.

Preparation and Characterization of Eggshell-shaped CuO/ZnO/SiO2 Particulate Catalysts Modified with Ce

XIA Zeng-min;WEN Li-Xiong;SONG Ji-rui;CHEN Jian-feng

. 2007, 7(4): 812-816.

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Eggshell-shaped CuO/ZnO/SiO2 and CuO/ZnO/Ce/SiO2 particulate catalysts supported with porous hollow SiO2 nanoparticles were prepared by a two-step precipitation method combined with addition of surfactant. The catalytic performances of the prepared catalysts for methanol synthesis from CO hydrogenation were investigated, and the catalyst structure was characterized by TEM, BET, XRD and XPS techniques. The results showed that the catalysts supported with porous hollow SiO2 nanoparticles had large specific surface areas, and the CuO and ZnO particles with an average size of about 13 nm were well dispersed on the support. The Ce promoter could improve the catalytic activity and the selectivity of methanol significantly, probably by two reasons: (1) Ce could lower the binding energy of Cu 2p3/2 and Zn 2p3/2, thus facilitating the reduction of CuO to Cu by hydrogen, and (2) the presence of Ce might enhance the interaction between Cu and Zn, and hence improved the dispersion of active components by preventing Cu particles from aggregating.

Synthesis and Characteristics of Layered LiNi0.8Co0.1Mn0.1O2 Cathode Material for Lithium Rechargeable Batteries

WANG Xi-min;WANG Xian-you;YI Si-yong;CAO Jun-qi

. 2007, 7(4): 817-821.

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Layered LiNi0.8Co0.1Mn0.1O2 powder was synthesized by reacting quasi-spherical Ni0.8Co0.1Mn0.1(OH)2 prepared by co-precipitation with LiOH×H2O through high temperature sintering route. The obtained powder was characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), thermogravimetric-differential thermogravimetric analysis (TG-DTG) and constant current charge-discharge cycling. The results revealed that the optimal preparation condition of the layered LiNi0.8Co0.1Mn0.1O2 was 750℃ under oxygen flowing. The XRD pattern of the sample prepared under the above condition could be identified by a typical structure of hexagonal a-NaFeO2 type. The SEM micrograph of LiNi0.8Co0.1Mn0.1O2 showed that a large number of spherical primary particles with an average size of about 500~800 nm piled loosely to form quasi-spherical secondary particles. Electrochemical measurements showed that it delivered an initial discharge capacity of 168.6 mA×h/g during the first charge and discharge cycle, and the first coulombic efficiency was 90.5%, and the discharge capacity in the 20th cycle was 161.7 mA×h/g. The material would be potential cathode material for Li-ion battery.

Preparation and Characterization of Alkaline Ca-bentonite Anhydrous Material

QIU Zhu;WEI Teng-you;LI Qi-lin;TONG Zhang-fa

. 2007, 7(4): 822-826.

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A kind of alkaline Ca-bentonite anhydrous material was presented for removal of water from organic vapor. The material was synthesized by activated clay and calcium hydroxide slurry under the drying condition. The effects of preparation conditions for alkaline Ca-bentonite anhydrous material on its dehydration behavior were investigated. The optimized anhydrous materials were characterized by FT-IR, SEM, XRD and DSC techniques. Compared with molecular sieves and cassava starch, the dehydration rate of alkaline Ca-bentonite is 12.1% at the 60℃, which is higher than that of molecular sieves and equivalent to cassava starch. The structure characterization results indicate that alkaline Ca-bentonite is of good thermal stability, easy regeneration and small adsorption heat. Furthermore, the material has a wide interlayer spacing leading to a rapid speed of water adsorption. The comprehensive comparison shows that alkaline Ca-bentonite has a better performance of dehydration than that of molecular sieves and cassava starch. The application result of the anhydrous material in ethanol vapor dehydration shows that it is satisfactory for the dehydration of organic vapor.

Effect of Non-aqueous Ball Milling on the Structure, Particle Size and Zeta Potential of Modified Silicon Dioxide

HU Hong-ying;HU Hui-ping;CHEN Qi-yuan

. 2007, 7(4): 827-831.

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The effects of non-aqueous ball milling on the structure and properties of modified silicon dioxide particles were investigated using X-ray powder diffraction, particle size analysis and zeta potential analysis, etc. The results indicate that the structure, particle size and zeta potential of modified silicon dioxide are related to the grinding conditions. Different modified silicon dioxide powder samples are obtained after ball-milling in air, DMF, DMF with 10% silane coupling agent, and DMF with 20% silane coupling agent, respectively. For example, after ball-milling 3 h, the average crystallite sizes of the above corresponding modified silicon dioxide samples are 46.9, 31.4, 24.5 and 75.9 nm, respectively, and average lattice distortion (e) of the above corresponding modified silicon dioxide samples is 0.0253%, 0.0871%, 0.117% and 0.063%, respectively. The medium diameters of the above corresponding modified silicon dioxide powder samples are 4.241, 1.586, 1.321 and 5.092 mm, respectively.

Advances of Constructal Theory in Engineering Applications

FAN Zhi-wei;ZHOU Xing-gui;YUAN Wei-kang

. 2007, 7(4): 832-839.

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In view of engineering design and optimization, applications of constructal theory in several engineering areas are introduced, especially in design and optimization of heat transfer and fluid distribution devices, the significance and potential value of constructal theory in engineering applications are highlighted. As a novel process system designing theory, constructal theory needs to be developed and improved. The application prospect of constructal theory in chemical engineering process/devices design and optimization is also discussed.

Recent Development in Metabolic Engineering for Production of Succinic Acid by Escherichia coli

ZHAN Xiao-bei;CHEN She;ZHENG Zhi-yong

. 2007, 7(4): 840-846.

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Succinic acid is an important chemical material with a big market. Its production by the method of microorganism fermentation can release the dependence of petroleum by the chemical synthesis method. Metabolic engineering made the production of succinic acid with recombinant Escherichia coli become possible, and much was done in the fermentation procession by metabolic engineering. However, the productivity of succinic acid fermentation by E. coli was still not high enough, and other organic acids were also found in the end products. So it seemed not very economical to the industrialization. In the post-genomic era, metabolic engineering is based on systems biology. More rational modification on E. coli will be achieved. In this paper, advances in metabolic engineering for improving succinic acid production by E. coli were reviewed, including the regulation of key enzymes and reconstruction of biosynthesis pathway of succinic acid. In addition, the prospect of succinic acid production was also discussed.

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