Table of Content

20 August 2009, Volume 9 Issue 4

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流动与传递

Numerical Simulation and Estimation of Energy Consumption for the Pneumatic Conveying Using Double-tube Socket

GUAN Chun-sheng; ZHANG Chun-xia; CHEN Ling; WEI Xiao-lin; MA Lv-xiang; ZHANG Yu;

. 2009, 9(4):  625-633. 

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A new method based on CFD (computational fluid mechanics) is used to estimate the energy consumption of DTS (double-tube socket) pneumatic conveying. The whole pipeline is divided into developing and fully developed parts. After CFD simulation of both parts the overall energy consumption is calculated. The results show that under the pressure gradient of 750 Pa/m in the developed part the predicted material flow rate is 10 t/h and the measurement material flow rate 8 t/h. Meanwhile the predicted gas consumption is 290 m3/h and the measurement gas consumption 240 m3/h. The predicted results are in fair agreement with the experimental results, suggesting that the new method is reliable and applicable.

Numerical Simulation on Fluid Flow of Xanthan Gum Solution Stirred by Different Types of Impeller

LI Jing; ZHAN Xiao-bei; ZHENG Zhi-yong; QI Xiang-ming; JIANG Yun; LIU Tian-zhong; LIU Li-ming;

. 2009, 9(4):  634-640. 

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The flow characteristics of a typical pseudoplastic fluid, xanthan gum solution, stirred by three different types of impeller in vessels were investigated. FLUENT? software, combined with standard k-e turbulent equations and multiple reference frame method, was employed to solve the problems numerically. The flow pattern, cavern volume, viscosity distribution, and power consumption of various concentrations of xanthan solution were obtained. Concentration of xanthan solution ranged from 0 to 2.0%(w), and impeller rotation speeds were 5 and 7.5 r/s, respectively. A remarkable effect of shear thinning was observed near the installation position, and there were significant differences of the distribution of liquid viscosity for each impeller. The impeller efficiency declined drastically with xanthan concentration, and increase of impeller speed barely improved impeller efficiency. When the xanthan concentration increased, power consumption generated by different flow patterns showed adverse results. When xanthan concentration was 2.0%(w) and rotation speed 7.5 r/s, the cavern volumes of all the operations were less than 60% of total vessel volume. Power consumption in the vessel with a Rushton turbine was dropped by 7%, while increased by about 29% with a Pitched blade turbine.

Detached Eddy Simulation of Turbulent Flow in an Unbaffled Stirred Tank Driven by a Rushton Impeller

YANG Feng-Ling;Yang ZHOU Shen-jie; ZHANG Cui-xun;

. 2009, 9(4):  641-646. 

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The detached eddy simulation (DES) model was employed to study the fluid flow behavior in an unbaffled tank stirred by a Rushton impeller. The result of turbulent flow obtained by standard k-e model was used as an initial solution for faster convergence of DES computation. By comparison with the literature results of large eddy simulation (LES) and PIV data, it was found that DES model could capture the instantaneous turbulent flow characteristics. The mean velocity profiles obtained by DES model showed good agreement with the LES and experimental results. There was only a tiny discrepancy (within 7%) between the mean tangential velocity obtained by DES and PIV. The maximum discrepancy between the DES predicted mean radial velocity and PIV result was not more than 12%. The results show that DES model has high potential in predicting the turbulent flow in stirred tanks, it can provide velocity profiles almost as accurately as the LES model does. Meanwhile, the computation cost of the DES model is only about 1/3 of the DES model.

Transfer Kinetics of Cu(II) through Bulk Liquid Membrane Using PC-88A as Carrier

YU Xiao-jiao; FAN Wei; YAO Bing-hua; ZHOU Xiao-de; ZHANG Jian-feng;

. 2009, 9(4):  647-651. 

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The effects of stirring speed, carrier concentration and reaction temperature on transport of Cu(II) ion through bulk liquid membrane was studied with chloroform as membrane solvent and 2-ethylhexyl phosphonic acid-mono-2-ethylhexylester (PC-88A) as carrier. The pseudo-first order apparent rate constants of interfacial transport of Cu(II) ions were determined. The apparent activation energy values are 31.65 kJ/mol for extraction and 23.11 kJ/mol for stripping, respectively. The kinetics of Cu(II) transport could be evaluated by two consecutive irreversible pseudo-first order reactions. In this condition the chemical reaction is the controlled step for extraction, and diffusion for stripping.

反应与分离

Seeded Induction Period and Secondary Nucleation of Lithium Carbonate

SUN Yu-zhu; SONG Xing-fu; WANG Jin; LUO Yan; YU Jian-guo;

. 2009, 9(4):  652-660. 

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Seeded nucleation of lithium carbonate in aqueous solution during reactive crystallization was monitored by FBRM (focused beam reflectance measurement) and PVM (particle video microscope). The impacts of operating variables, such as seed size and loading, stirring speed, on induction period and secondary nucleation were investigated and explained by an adsorption model. The results show that seed surface area plays an important role in secondary nucleation, for more surface area has higher adsorption capacity and consumes more supersaturation on seed growth, thus restrains nucleation better. A method through comparison between pure breakage/attrition and nucleation process was put forward to distinguish attrition-induced and surface-induced nucleations quantitatively, which can reveal the contributions of different nucleation mechanisms. The nucleation processes in different conditions were studied, the principles and valuable experimental data were obtained for seeding approach primarily. FBRM and PVM are useful on-line apparatuses to facilitate seed selection and seeding optimization.

Unseeded Induction Period and Primary Nucleation of Lithium Carbonate

SUN Yu-zhu; SONG Xing-fu; WANG Jin; LUO Yan; YU Jian-guo;

. 2009, 9(4):  661-668. 

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A set of laser apparatus was used to study induction period and primary nucleation of lithium carbonate in reactive crystallization. The results show that induction period increases with the decrease of supersaturation degree and temperature. Magnetic field has nearly no impact on it, while the use of ultrasound reduces it obviously. The impacts of some impurities and additives on primary nucleation were investigated. It is found that the presence of Na2SO4, NH4Cl, (NH4)2SO4 and EDTA disodium prolongs induction period, whereas KCl, NaCl, NaBr and CH4N2O can decrease it. Many important parameters of primary nucleation are also obtained, as temperature goes up from 283 to 313 K, interfacial tension decreases from 44.8 to 41.5 mJ/m2, contact angle varies from 82.9o to 88.7o, nucleation order is between 5.0 and 5.4, surface entropy factors are all above 5, suggesting that the growth mechanism is a spiral growth. Besides, both the homogeneous and heterogeneous primary nucleations were monitored with on-line focused beam reflectance measurement.

Influence of Mechanical Activation on Alkaline Leaching and Physicochemical Properties of Zinc Oxide Ore

CAO Qin-yuan; LI Jie; XIA Wei;

. 2009, 9(4):  669-675. 

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The effects of mechanical activation on alkaline leaching and physicochemical properties of zinc oxide ore from Lanping, Yunnan were studied using a combination of scanning electron microscope analysis, particle size distribution, thermogravimetry and X-ray diffraction. The results demonstrated that when the solution was NH4Cl 2.0 mol/L, NH3×H2O 1 mol/L, the temperature 30℃, and the ratio of ammonia-ammonium chloride solution volume to the ore mass 10 L/g, the zinc leaching rate of 90 min milled sample after leaching for 90 min was 69.36%, while the unmilled sample was just 60.08%. Besides, leaching after milling had a more promising effect than the mechano-chemical leaching mode. Meanwhile, different milling times and modes could lead to different morphologies, particle size distributions, thermal behaviors, crystallite sizes and lattice strains. In addition, the phase transference during the activation modes was different, which caused different zinc leaching rates in the alkaline solution.

Purification of Leaching Solution of Spent NixCoyMnz Battery Material by Removing Cu and Fe

LI Jin-hui; LI Xin-hai; ZHOU You-yuan; HU Qi-yang; ZHANG Ming; ZHANG Lian-xin ZHANG Ming

. 2009, 9(4):  676-682. 

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The removal of copper and iron impurities from leaching solution of NixCoyMnz spent battery material is studied. The copper is removed through replacement by iron powder, while the effects of Fe powder amount, reaction time and reaction temperature on the copper removal and loss of nickel, cobalt and manganese are examined. And the iron is removed by precipitation in the copper removed solution, while the conditions of pH value, reaction time and reaction temperature are discussed, which can influence the iron removal and the loss of nickel, cobalt and manganese. The result shows that Cu and Fe can be removed 99% at least. And at the same time, the loss rates of Ni, Co and Mn are about 2%, 3% and 2%, respectively. The leaching solution after purification accords with the demand of preparation of NixCoyMnz ternary system precursor.

Three-phase Extraction of Zn2+ and Mn2+ from Their Sulfate Solution

JIN Sheng-chao; CHANG Zhi-dong; WANG Kang; HUA Chao; YU Pin-hua; LIU Hui-zhou; LIU Hui-zhou;

. 2009, 9(4):  683-688. 

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Three-liquid-phase extraction system (O-W1-W2) was formed by P204 dissolved in kerosene (oil phase, O), PEG 10000 solution (first water phase, W1) and ammonium sulfate solution including Zn2+ and Mn2+ (second water phase, W2). Its extraction of Zn2+ and Mn2+ was compared with solvent extraction (O-W'2, sulfate solution of Zn2+ and Mn2+ as W'2) and aqueous two-phase system (W1-W2). The results showed that after adding KSCN, O-W1-W2 could separate Zn2+ and Mn2+ at one step effectively. Increasing molar ratio of SCN- to Zn2+ from 10 to 60, W1 phase only extracted Zn2+ and the total extraction rate of Zn2+ in O-W1-W2 (90%) was higher than that of O-W'2 and W1-W2 (52.8% and 86.2% respectively). Extraction rate of Mn2+ in O phase was higher than that of O-W'2 (10.2%).

Extraction of Essential Oil and Carthamin from Safflower Dreg with Supercritical CO2

HAN Xiao-jin; ZHANG Rong; BI Ji-cheng;

. 2009, 9(4):  689-694. 

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To obtain safflower essential oil and carthamin from safflower dreg by supercritical CO2 two-step extraction, a series operational parameters of pressure, temperature and CO2 flow rate were investigated in a bench-scale apparatus. The result shows that the rise of CO2 flow rate and the decrease of temperature lead to the increase in extraction rate of safflower dreg. Furthermore, the optimum conditions of extraction of safflower dreg are: in the first-step extraction, temperature at 35℃, pressure at 9 MPa, CO2 flow rate at 3.74 kg/h, in the second-step extraction, temperature at 35℃, pressure at 30 MPa, and CO2 flow rate at 3.74 kg/h. The extraction rates of essential oil and carthamin are 2.74% and 69.88%, respectively.

Process Simulation on Absorption of Benzene Using n-Formyl Morpholine Solution in Hydrophobic Polypropylene Hollow Fibers

LI Rui; XU Jun; WANG Lian-jun; LI Jian-sheng; SUN Xiu-yun;

. 2009, 9(4):  695-700. 

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A membrane based gas absorption process for the separation of benzene (C6H6) from C6H6/N2 mixture gas was studied. The aqueous solution of n-formyl morpholine was used as absorbent and hydrophobic polypropylene hollow fiber membrane as gas-liquid contactor. For non-wetted mode, a differential model was presented to simulate the mass transfer process of C6H6 in the tube side and membrane pore of hollow fiber. The values of C6H6 absorption rate were also predicted to compare with experimental values. The results show that the absorption rate achieved (0.89~6.13)′10-2 mg/(m2×s) under the experimental conditions. The average error of absorption rate of model predicted was 1.9%, and the model could more accurately describe absorption process in hollow fibers.

Effect of Binder on Simultaneous SO2 Removal and NO Conversion over Activated Carbon Honeycomb Supported V2O5 Catalyst

WANG Yan-li; LIU Zhen-yu;

. 2009, 9(4):  701-706. 

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A series of V2O5/ACH catalysts were prepared by supporting V2O5 on activated carbon honeycomb (ACH). Silicate and phenolic resin were used as binders, respectively. Two types of V2O5/ACH catalyst were studied for simultaneous SO2 removal and NO conversion. The results indicate that the silicate binder affects the amounts of carbon and alkali metal oxides in the catalyst and subsequent SO2 removal and NO conversion rates, therefore, the ACH with higher carbon and lower alkali metal oxide contents is preferred. The catalyst with phenolic resin has high carbon amount and micropore volume, and hence higher SO2 removal rate, but lower NO conversion rate. The high proportion of oxygen and carbon in the ACH with the silicate results in improvement of NO conversion. However, the silicate decreases SO2 removal rate by reducing the micropore quantity of ACH and decreasing the specific surface area and micropore volume of the catalyst. Under the optimal conditions of ACH with 30% silicate or with phenolic resin carbonized at 900℃, over 90% NO conversion rate for the catalyst with the silicate can be reached, and SO2 capacity for the catalyst with phenolic resin is 7.3%(w).

Preparation, Characterization and Adsorption to Pb2+ of Magnetically Modified Zeolite

YUAN Ming-liang; YAN Guan-jie; TAN Mei-yi; TAO Jia-hua;

. 2009, 9(4):  707-711. 

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A composite of natural zeolite with magnetite was prepared by urethane coating. The magnetically modified zeolite (MMZ) was characterized by XRD, SEM, nitrogen adsorption isotherms, and magnetization measurements. The results showed that the structure of MMZ did not manifestly change, compared with the Na-zeolite, and the BET specific surface area increased from 25.13 m2/g for the Na-zeolite to 38.01 m2/g for the MMZ. The adsorption properties of Pb2+ on both zeolites were studied. The equilibrium adsorption capacities on the MMZ and Na-zeolite were 54.53 and 66.99 mg/g, respectively. The adsorption data of Pb2+ on the MMZ and Na-zeolite fitted the linearized Langmuir equation reasonably well, and the monolayer maximum sorption capacities were 50.89 and 65.92 mg/g, respectively.

Foam Fractionation of Protein with Existence of Antifoam Agent

XU Zhong-he; WU Zhao-liang; ZHAO Yan-li;

. 2009, 9(4):  712-716. 

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Surfactant-assisted foam separation process was conducted with a stimulated system using bovine serum albumin (BSA) as targeted protein, and polyoxypropylene polyoxyethylene glylerin ether (PGE) as antifoam agent. The effects of surfactant type (nonionic/ionic), concentration, solution pH and operating factors of G (gas flow rate) and HL (initial liquid pool height) on protein separation efficiency were investigated respectively. The results revealed that nonionic surfactant Tween-20 and ionic SDBS could enhance the system foam capacity and stability, so that the foam process could be operated, while the latter exhibited higher performance and prompted protein adsorption efficiently on the condition the negative charge DBS- attached to BSA with opposite charge via electrostatic force to form a more hydrophobic complex DBS-BSA. And, pH had a strong influence on protein adsorption by affecting the bonding between SDBS and BSA, since the charge distribution of protein molecule surface varied with pH. About 66% of BSA was concentrated in the foamate and the enrichment ratio was 5.34 with initial BSA concentration 0.1 g/L, PGE 4 mg/L, SDBS 50 mg/L, and pH 3.4. A higher BSA recovery rate could be obtained by increasing G or HL, but the enrichment reduced.

Preparation of Magnesium Hydroxide from Magnesium Sulfate by Ammonia Method with a Pilot-scale Apparatus

MA Guo-bao; LI Xue; LI Zhi-tao; XU Sheng-bo; LIU Yun-yi;

. 2009, 9(4):  717-721. 

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Preparation of magnesium hydroxide from boric magnesium fertilizer (with MgSO4×7H2O as the main component) by NH3-bubbling method was carried out in a self-designed pilot-scale apparatus. The properties of prepared magnesium hydroxide particles were measured with SEM, XRD and TG-DTA, respectively. The influences of operation forms and reaction conditions on the particle properties were investigated. The results showed that the products obtained in batch and continuous operations were of remarkable difference in their particle morphology, which changed gradually with transition from batch operation to continuous operation and tended to be in the same morphology while the reaction time lasted 13 h. The pH value of reaction solution and conversion rate of Mg2+ were maintained at about 9.5~10.0 and 80%, respectively. Hydrothermal treatment of the products obtained in continuous operation resulted in that the magnesium hydroxide particles were hexagonal platelets in morphology, 2 mm in size, more than 2 in the value of I001/I001 and at 393.2℃ of the strongest endothermic peak, which could be used as flame retardant additive in polymer materials.

过程与工艺

Micellization, Interaction and Microenvironment in the Mixed Solution of Pluronics and Surfynol 104 with Nuclear Magnetic Resonance

SONG Han; GUO Chen; MA Jun-he; XIANG Jun-feng; TANG Ya-lin; LIU Hui-zhou; LIU Hui-zhou;

. 2009, 9(4):  722-730. 

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The micellization, intermolecular interaction and microenvironment of molecular segments in the mixed aqueous solution of PEO-PPO-PEO triblock copolymer (Pluronic? F88, P84 and P123) and Surfynol? 104 (S104) were studied by nuclear magnetic resonance method. The results showed that the addition of S104 decreased the critical micellization temperature of copolymer. When its concentration was 0.5 g/L, the most reduction was up to more than 10℃ for F88, which was most hydrophilic in the selected copolymers. This reduction was caused by the hydrophobic interaction between S104 molecules and PPO segments. The addition of S104 enhanced the hydration of PEO segments most obviously for P123. And S104 slightly increased the hydration of PPO segments before the micellization, but obviously decreased their hydration after micellization, which was attributed to the hydrophobic interaction mentioned above and temperature rising. This effect was most observable for F88.

Characteristics of Biomass Gasification by Decoupling Drying/Pyrolysis and Char Gasification

HU Jing-hui; WANG Yin; LIU Xin-hua; JIANG Deng-gao; XU Guang-wen;

. 2009, 9(4):  731-737. 

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Using a laboratory two-stage fixed-bed reactor, the characteristics of decoupling gasification (DG) of beer lees, in comparison with that of traditional coupling gasification (CG), were investigated on tar yield, carbon conversion rate and gasification efficiency. Experimental results showed that under the reaction temperature of 550℃ for pyrolysis, 800℃ for gasification in DG and 800℃ in CG, water content of 40%(w) in the fuel and O2 content of 4%(j) in the gasification reagent, compared with CG, the tar yield was decreased by 35.3%, the gasification efficiency, carbon conversion rate and gas yield were increased by 4.0%, 18.4% and 20%, respectively in DG. Examination of the effects of water content in the fuel (0~80%, w), gasification temperature (800~900℃) and oxygen content in the gasification reagent (4%~6%, j) demonstrated that DG led to more considerable influences than CG did by causing higher H2 or CO content in the produced gas and higher carbon conversion rate.

Preparation of Boehmite from Supersaturated Solution of Sodium Aluminate with Ethanol-Water Solvent

YANG Liu; WANG Zhi; GUO Zhan-cheng;

. 2009, 9(4):  738-744. 

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Boehmite was prepared from supersaturated sodium aluminate solution with ethanol-water solvent. The effects of mass ratio of ethanol (w) and temperature on decomposition rate, diameter and phase composition of alumina hydrate, precipitated from supersaturated sodium aluminate solution were studied, and the obtained product was characterized. The results indicated that the mass ratio of AlOOH in the product increased significantly with the increase of mass ratio of ethanol because of the reduction of free caustic concentration and increase of initial supersaturation coefficient. When w=1.0, the mass ratio of AlOOH in the product reached the peak of 90%. The decomposition rate of supersaturated sodium aluminate solution and mass ratio of AlOOH in the product increased with the decrease of temperature. The addition of ethanol changed growth speeds of product in longitudinal and radial direction and the product changed from plate like crystals to long column agglomerates.

Thermodynamic Equilibrium Analysis on Cu(II)-Glu2--CO32--H2O System

YANG Tian-zu; LIU Zhen-zhen; REN Jin; DOU Ai-chun; LIU Wei; LIU Wei-feng; ZHANG Du-chao;

. 2009, 9(4):  745-749. 

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Leaching behaviors of basic cupric carbonate [CuCO3×Cu(OH)2] as general phase in low grade cupric oxide ore with L-monosodium glutamate were studied, and thermodynamics of Cu(II) complex equilibrium in Cu(II)-Glu2--CO32--H2O system was studied by coordination chemistry principle. Varying the concentration of L-monosodium glutamate and pH value in the ranges of 0~3 mol/L and 5~14 respectively, the equilibrium thermodynamic diagrams were drawn, and the effects of L-monosodium glutamate concentration, pH value and free carbonate ion concentration on leaching of basic cupric carbonate were also studied. The comparison of theoretical calculation and experimental result shows that the absolute average value of relative error between them is 5.32%. The results indicate that the critical data and the thermodynamic model are convincible. Therefore, it is feasible to leach low grade cupric oxide ore with L-monosodium glutamate.

Preparation and Application of Calcining Seed in the Production Process of Rutile Titanium Pigment

ZHAO Yan; WANG Li-na; QI Tao; CHU Jing-long;

. 2009, 9(4):  750-753. 

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Calcining seed of rutile titanium dioxide was prepared at low temperature using metatitanic acid as raw material through alkaline hydrolysis, hydrolysis reaction, first washing, neutralization reaction, second washing and acid dissolution. These kinds of seed were added in the salt treatment, and the influences of calcining seed and calcination temperatures on the content of rutile TiO2 pigment were examined systemically. The results indicated that above 90% rutile titania gel with high stability could be obtained under the conditions as follows: reaction temperature of 100℃, slurry concentration (based on TiO2 concentration) in 90~120 g/L, mass ratio of HCl to TiO2 in 0.3~0.5, reaction time for 90~120 min. During the salt treatment, the rutile TiO2 content could be more than 99% when the content of seed was 3%~5% at the calcination temperature of 900℃ for 2 h.

生化工程专栏

Preparation of Uniform Size PLGA Microparticles and Microcapsules by Premix Membrane Emulsification

TIAN Rui; WANG Lian-yan; WU Jie; ZHANG Jie; ZENG Ye-jing; MA Guang-hui;

. 2009, 9(4):  754-762. 

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Glucagon-like peptide-1 (GLP-1) loaded poly(lactic-co-glycolic acid) (PLGA) microspheres were prepared by premix membrane emulsification and solvent extraction method. The preparation conditions of PLGA microparticles were optimized with respect to particle size and size distribution. The final optimum conditions were as follows: transmembrane pressure 1000 kPa, transmembrane pass 3, concentration of poly(vinyl alcohol) (PVA) in external water phase 19 g/L and volume ratio of oil phase to external water phase 1:5. The prepared microparticles under the conditions showed perfect spherical geometry and suitable size distribution. Under these conditions, uniform-sized GLP-1 loaded PLGA microspheres with different molecular weights were successfully prepared, the average diameter was about 300 nm, GLP-1 encapsulation efficiency 65%, and bioactivity 85%. Subsequently, their drug release in vitro was tested in phosphate buffered saline (pH 7.4) for 20 d.

Preparation of Uniform Polydivinylbenzene Microspheres and Their Application in Reversed-phase Chromatographic Separation of Small Molecular Compounds and Peptides

WANG Jing; QU Huan-huan; HAO Dong-xia; GONG Fang-ling; MA Guang-hui;

. 2009, 9(4):  763-769. 

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Taking divinylbenzene as monomer, polydivinylbenzene (PDVB) microspheres with particle size 25 mm were prepared by membrane emulsification and suspension polymerization at 75℃. Their morphology and size distribution of pores were investigated, their application in reversed-phase chromatographic separation of small molecular compounds and peptides examined. The prepared PDVB microspheres had uniform particle size (span value=0.91), mean pore size of 14 nm, specific surface area of 520 m2/g, and high mechanical intensity (keeping stable under 40~50 MPa pressure). The PDVB microspheres were packed into semi-preparative columns (300 mm×10 mm I.D.) and tested by separating phenol derivatives and peptides mixture on high performance liquid chromatography. The resolution of both systems was higher than 1.5, and theoretical plate number reached 13000 and 21000 m-1, respectively. PDVB microspheres showed perfect batch to batch reproducibility on separation. They would be a promising reversed-phase stationary phase for preparative and process purification of peptides.

Preparation and Characterization of Polystyrene Support for Solid Phase Organic Synthesis of RNA

LIANG Hong; LI Peng; ZHANG Jing; SU Zhi-guo;

. 2009, 9(4):  770-775. 

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A new universal polystyrene support for solid phase organic synthesis of ribonucleic acid (RNA) was prepared efficiently through the attachment of 3-amino-1-(4,4￠-dimethoxytriphenylmethyl)-1,2-propanediol linker and aminomethyl-polystyrene support via succinic anhydride. The synthetic efficiencies of the new support and traditional controlled pore glass (CPG) support were almost at the same level. The loading of activating site of the new support was 61~92 mmol/g, which was much higher than that of the latter. Moreover, the new support could be used as a universal support to synthesize any sequence RNA. The condition of cleavage and deprotection of the product was very mild. RP-HPLC analysis showed that the product synthesized on universal polystyrene support and CPG support was identical, and no degradation was found. This universal solid support may replace conventional CPG support.

Preparation of Biocompatible Microcapsules Templated on Calcium Carbonate Microspheres

JIN Yi; ZHU Yi-hua; LIU Wang-cai; WANG Jia-rong; FANG Jiang-hua;

. 2009, 9(4):  776-780. 

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Poly(sodium 4-styrenesulfonate) (PSS) was used to synthesize calcium carbonate (CaCO3) microspheres with different morphologies. The influences of different functional group unit molar ratios of [PSS]/[Ca2+] on the morphology and crystal phases of CaCO3 microspheres were studied by high scan electrode microscope and X-ray diffraction. These synthesized microspheres were used as the template of microcapsules. Protamine sulfate (PRM) and dextran (DXS) were self-assembled on the surface of obtained microshperes by layer-by-layer self-assembly technique. After the CaCO3 was dissolved, the microcapsules were obtained. The controlled release behavior of hollow capsules was examined in the sample of chlorogenic acid. The result shows that the encapsulated rate and loaded drug amount were 83.55% and 37.41 mg/mg, respectively. The (DXS/PRM)6 capsules demonstrated obvious controlled release effect.

Separation of S-Benzyl-g-L-glutamyl-L-cysteine Using Ion-exchange Method

LIU Bu-yun; ZHOU Zhi; YAO Zhong; WU Ming-gang; SONG Xi-wen; SHE Wei-na; XIAO Yan-ling; WEI Ping;

. 2009, 9(4):  781-785. 

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The synthesized S-benzyl-g-L-glutamyl-L-cysteine (S-Bzl-GGC) with enzymatic methods was purified with ion-exchange method by using Q sepharose FF as adsorbent. The adsorption isotherm was investigated, and Sips equation provided the best fitting of experimental data. The influences of pH value, elution gradient, flow rate and sample quantity on the separation process were also discussed. The results showed that S-Bzl-GGC could be well separated at the conditions of pH 8.2, salt elution gradient of 0~30% B, 12 mL, flow rate of 2 mL/min and sample size of 500 mL. Under the optimal conditions, the purity of product was 98.5% after one step purification and the structure of product was further identified by 1H-NMR.

Enhancement of Glutathione Production by Combining Cysteine Addition with Dissolved Oxygen Control and Low pH Stress in High Cell Density Cultivation of Candida utilis

LIANG Guo-bin; DU GUo-cheng; CHEN Jian;

. 2009, 9(4):  786-790. 

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The effects of cysteine addition coupled with dissolved oxygen (DO) control and pH stress on glutathione (GSH) production in high cell density (HCD) cultivation of Candida utilis were investigated. By applying HCD cultivation, cell concentration reached 102 g/L and GSH yield was 981 mg/L after 45 h fermentation. At 45 h, single-shot addition of cysteine was utilized to increase GSH production, the results indicated that the 50 mmol/L cysteine addition achieved a maximal GSH yield of 1534 mg/L after 60 h cultivation. In addition, the method of two-step DO control after cysteine addition, by which DO was controlled at 5% in the first 3 h and at 20% in the following 12 h, was developed. As a result, cysteine addition was decreased from 50 to 30 mmol/L, while GSH yield reached 1734 mg/L at 60 h. Moreover, by adopting the strategy of combining two-shot cysteine addition (15 mmol/L for each time) with two-step DO control and low pH stress, a maximal GSH yield of 1936 mg/L was achieved at 60 h.

Biosynthesis of Poly-g-glutamate Acid by Escherichia coli

MA Jie; WANG Dan; LI Qiang; XING Jian-min; LIU Hui-zhou;

. 2009, 9(4):  791-795. 

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The genes, ywsC, ywtA and ywtB, involving in biosynthesis of poly-γ-glutamic acid were amplified by PCR from the genome of Bacillus subtills 168. Sequence blast result showed that the sequence of target genes was 100% the same as that of B. subtilis 168. The genes were then inserted to the plasmid pTrcHisA and transformed into E. coli TOP10 and E. coli BL21 (DE3) host cells. The result indicated that both the strains obtained the ability to biosynthesize poly-g-glutamic acid, and the highest yield of g-PGA reached 0.134 g/L.

Ethanol Fermentation from Jerusalem Artichoke Juice with Self-flocculating Yeast Saccharomyces cerevisiae flo

CHANG Bao-lei; YUAN Wen-jie; ZHAO Xin-qing; REN Jian-gang; BAI Feng-wu;

. 2009, 9(4):  796-800. 

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Batch and continuous processes were studied for ethanol production by fermentation of Jerusalem artichoke juice with self-flocculating yeast Saccharomyces cerevisiae flo. In the batch fermentation, ethanol production was more efficient with the simultaneous saccharification and fermentation (SSF), compared with the separate hydrolysis fermentation (SHF). The highest ethanol concentrations of 50 and 82 g/L were achieved within 26 and 34 h when Jerusalem artichoke juice containing total sugar concentrations of 105 and 179 g/L was used in the batch SSF, 6.4% and 13.8% higher than those achieved in the corresponding SHF. When the continuous SSF was applied, steady state was observed when the dilution rate of fermentation system was maintained at 0.02 h-1, and 90 g/L ethanol was produced in the effluent, being equivalent to 90% of its theoretical value. The ethanol productivity was further calculated to be 2.12 g/(L×h). Moreover, the fermentation of unsterilized raw Jerusalem artichoke juice was examined and no contamination was observed, indicating that such a process could be more competitive in saving energy consumption.

Preparation of (R)-1-Phenyl-1,2-ethanediol by Biotransformation with a Coupled System of (R)-Specific Carbonyl Reductase and Formate Dehydrogenase

ZHANG Rong-zhen; XU Yan; DI Ya-wei; WANG Shan-shan; SUN Ying;

. 2009, 9(4):  801-805. 

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The effects of reaction temperature, pH value, initial substrate concentration, reaction duration, cell concentration and forms on biotransformation reaction for preparation of (R)-1-phenyl-1,2-ethanediol were studied with 2-hydroxyacetophenone and sodium formate as substrates and the whole cells of E. coli Rosetta/pETDuet-rcr-fdh as catalyst .The results showed that when the concentration of 2-hydroxyacetophenone was 6 g/L, (R)-1-phenyl-1,2-ethanediol was produced with high optical purity of 98.37% enantiomeric excess and yield of 79.14% at the conditions of temperature 35℃, pH 7.0, reaction duration 36 h and wet cell concentration 10%(w). Further research showed that the biotransformation efficiency could be well improved by addition of Zn2+. In the presence of Zn2+ with a final concentration of 5 mmol/L, the enantiomeric excess and yield reached 100% and 86.3%, respectively.

材料工程专栏

Effect of Calcination Temperature on Catalytic Performance of Bimetallic Catalysts for Hydrogenation Reforming of Toluene

CHENG Hong-wei; LU Xiong-gang; LI Lin; WANG Xue-guang; YUE Bao-hua; DING Wei-zhong;

. 2009, 9(4):  806-812. 

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A series of Ni-Co/Mg(Al)O catalysts were prepared by calcination of Ni-Co/Mg(Al)O hydrotalcite precursor at various temperatures and used in the hydrogenation reforming reaction of toluene as a model tar compound. A C7H8 conversion rate of 100%, CH4 yield of 34% and CO yield of 66% were achieved for 35 h over the catalyst calcined at 850℃ under atmospheric pressure at 800℃ and GHSV of 12000 h-1 with a H2O/C molar ratio of 0.7, which was better than those calcined at the temperature lower than 750℃ or higher than 950℃. The catalyst calcined at 850℃ showed higher specific surface area, stronger interaction between active metals and carrier due to the formation of spinel and solid solution phases as well as smaller particulates and highly homogeneous dispersion of active metals. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of it could be removed in the hydrogen-rich atmosphere. The carbon deposition on catalysts was a reversible process.

Fabrication and Characterization of General Microcups with Flexibility and Solvent-resistance by UV Photo-mask Lithography

WANG Jian; MENG Xian-wei; TANG Fang-qion;g REN Xiang-ling; REN Jun; ZHANG Lin;

. 2009, 9(4):  813-818. 

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To develop a simple low-cost method for general microcups of electronic paper, the chosen methacrylic ester formulation consisted of some function units, such as solvent-resistance units, flexibility and adhesion promoting units, was accomplished through photo-mask lithography. The solvent-resistance units were the compact network structure obtained by crosslinked oligomers with carboxylic acid. Furthermore, the flexibility and adhesion promoting units were flexible materials obtained by polyester, urethane, isobornyl acrylate, their structures were similar to plastic substrates. Moreover, the microcup structures on glass, polyester or conductive electrode substrate were determined to possess excellent solvent-resistance and airtightness in tetrachloroethylene under 100℃, rigidity of 3H measured by pencil hardness, curl diameter from 2 to 3 mm, average T type peeling strength of 0.50 N/mm on polyester substrate, and cross-cut test value of zero grade. Therefore, the microcup structures are suitable for electrophoretic display devices on flexible substrates with tetrachloroethylene as electrophoretic medium.

Synthesis of ZrO2-based Catalyst Support by Improved Sol-Gel Method with H2O2 Oxidation

YANG Wei-jiao; TANG Qing; LI Rui-xing; LIU Hai-tao; LI Hui-quan;

. 2009, 9(4):  819-823. 

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Nano-sized tetragonal ZrO2 particles from 12 to 16 nm in diameter were successfully synthesized by an improved sol-gel method, assisted with a distillation-dehydration process after oxidization of Cl- anions by H2O2. The microstructure of synthesized ZrO2 particles was characterized with SEM, TEM, XRD and thermal analysis. The effects of molar ratio of H2O2 to ZrO2, distillation temperature and calcination temperature on the microstructure of ZrO2 powder were studied. The optimum conditions were obtained as follows: molar ratio of H2O2 to ZrO2 1:2, distillation temperature 80℃ and calcination temperature 500℃. Spherical-like nano-sized tetragonal ZrO2 particles could be obtained by the process, and the reactivity of this ZrO2 loading 5%(w) Cr2O3 for propane dehydrogenation oxidized by CO2 was as follow: 53.4% propane conversion rate, 38.1% propylene yield and 33.3% CO2 conversion rate.

Synthesis and Characterization of Oil-based Fe3O4 Magnetic Fluid and P(St-GMA-DVB) Polymer Magnetic Microspheres

ZHANG Xiao-qiang; LI Rong; ZHOU Xin; LIU Jun-feng;

. 2009, 9(4):  824-828. 

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Oil-based Fe3O4 magnetic fluid was prepared using FeCl3·6H2O and FeCl2·4H2O by chemical coprecipitation method and the process route was chosen to overcome the agglomeration difficulty of magnetic particles in the synthesis process of Fe3O4 magnetic fluid. The magnetic fluid had good dispersion and stability, and its saturation magnetization was up to 72.60 emu/g. P(St-GMA-DVB) polymer magnetic microspheres were synthesized by suspension polymerization method. The stirring speed had greater impact on magnetic microsphere particle size, and the magnetic microsphere particles were in the range of 55~300 mm. The appearance of magnetic microsphere was monodisperse spherical, and the content of epoxide could be achieved 17 mmol/g.

Wettability of Sn-Zn, Sn-Ag-Cu and Sn-Bi-Cu Lead-free Solder Alloys with Copper Substrate

ZHANG Xiao-rui; WANG Chun-lei; ZHAO Hong-xin; LI jian-qiang; TYUAN Zhang-fu

. 2009, 9(4):  829-832. 

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The wettability of Sn-Zn, Sn-Ag-Cu, Sn-Bi-Cu solder alloys on copper substrate was measured by sessile drop method. Among these solder alloys studied, the wettability of Sn-Bi-Cu alloy was excellent, at 530 K the contact angle between Sn-30Bi-0.5Cu alloy and Cu substrate was 26o. There was almost no contact angle hysteresis of the molten ternary eutectic Sn-3Ag-0.5Cu alloy. Adding Bi to Sn-based alloys could improve the wettability of alloys, while adding Cu could prevent the occurrence of dissolution of Cu substrate effectively. These research results may provide some theoretical basis for the use of lead-free solder alloys.