The Chinese Journal of Process Engineering

Experimental and Numerical Investigations of an Ice-Slurry Generator

HONG Ruo-yu;DONG Liang;SHANG De-yi;XU Jian-sheng;Kawaji M

. 2004, 4(1): 1-7.

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A new test facility equipped with refrigerant and brine circulation systems, and a rotating-scraper ice-slurry generator was constructed to analyze the ice-slurry flow and heat transfer accompanied by phase change in an industrial generator. The axial and transverse brine temperature and ice fraction concentration profiles in the ice generator were measured. The heat transfer efficiency lower than the average was identified in the upper half of the ice generator and its cause was determined by conducting three-dimensional numerical simulation using a commercial CFD code, FLUENT. Approaches of improving the brine-side heat transfer rates were investigated by incorporating extra mixing blades from numerical simulation.

Hydrogen Evolution Reaction on Amorphous Ni-P Electrodes Produced by Electrodeposition

CHEN Yan-li;LI Ling-chuan;ZHANG Yi;CAO Hong-bin

. 2004, 4(1): 8-11.

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Ni-P alloy electrodes with different phosphorus contents were prepared by means of electrodeposition method. The catalyzing property of the different electrodes as the hydrogen evolution-cathode in 1 mol/L KOH solution at 20℃ was studied with constant current polarization method. The structures of Ni-P alloy electrodes were also analyzed by XRD and SEM. The results show that the Ni-P alloy electrode with phosphorus content of 8.49 at% (atomic percent) performs excellent catalyzing property. Its hydrogen evolution overpotential is 95 mV, the lowest at the current density of 150 mA/cm2, which is 342 mV lower than that of Ni electrode. And its Tafel slope in the low current density is 65.4 mV/dec. This property is related to its phosphorus content and structure.

Acidic Dissolution Behavior of Iron in the Floated Tails of Complicated Bauxite

YUAN Ming-liang;ZHAO Guo-hun;HU Yue-hua

. 2004, 4(1): 12-15.

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The dissolving behavior of iron in bauxite tails in vitriol solution was studied. The results show that the Fe2O3 in tails can dissolve in vitriol solution rapidly, and the property of aluminum bronze in bauxite is not changed, which offers good conditions to processing and utilization of bauxite tails. The effects of reaction temperature, oxalic acid and vitriol concentration on the dissolving rate of iron were discussed in detail and the best conditions of reaction temperature 80℃, reaction time 3 h, vitriol concentration 2.70 mol/L, oxalic acid concentration 0.25 mol/L, liquid solid ratio 1:6 are suggested.

Effect of Nitrogen Source on Heterotrophic Growth of Transgenic Chlorella and Rabbit Defensin Expression

HAN Xing-mei;LI Yuan-guang;WEI Xiao-dong;SUN Yong-ru;WANG Yi-qin

. 2004, 4(1): 16-21.

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The influence of nitrogen sources on the heterotrophic growth of transgenic Chlorella and rabbit defensin (NP-1) expression in a 250 ml flask was investigated. The results showed that KNO3 and yeast extract were the optimal nitrogen sources for the heterotrophic culture of transgenic Chlorella with NP-1 gene. Dry weight cell density of transgenic Chlorella was improved from 3.29 g/L to 5.11 g/L and NP-1 expression capability kept unchanged as the concentration of KNO3 and yeast extract were 0.9 g/L and 9 g/L respectively. Batch culture of transgenic Chlorella with NP-1 gene in a 5 L bioreactor with the optimized medium was conducted and the process characteristics were also analyzed. It was found that KNO3 was consumed quickly and organic nitrogen was enough in the medium, and chlorophyll and protein contents of transgenic Chlorella decreased while NP-1 expression capability kept unchanged.

Expression of Gloshedobin from the Venom of Gloydius shedaoensis in E. coli

HUANG Xing;LIU Zheng;YANG Qing;YAN Ming

. 2004, 4(1): 22-27.

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The gene of gloshedobin was cloned into pET-32a(+) and expressed in Escherichia coli under T7 promoter with a fusion partner of a Thx.Tag and a 6xHis.Tag. The stability of the plasmid was confirmed according to pET protocol. The effects of induction time, induction temperature and IPTG concentration on the expression, particularly the expression of target protein over impurities, were examined. The maximum expression in the inclusion body was obtained at induction time of 2~3 h, induction temperature of 37oC and IPTG concentration of 0.02 mmol/L. Effects of metal ions on the expression were examined by orthogonal design. Fe3+, Co2+ showed positive stimulation on the expression of insoluble target protein, while the effect of Ca2+ has minor promotion. In contrast, decreased expression was observed as Mg2+ was added in culture media.

Effects of Sucrose, Lactate and KH2PO4 on Nisin Production by L. lactis sp. lactis ATCC11454

LU Wen-hua;CONG Wei;CAI Zhao-ling

. 2004, 4(1): 28-31.

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The effects of sucrose, lactate and KH2PO4 on cell growth and nisin production kinetics of L. lactis sp. lactis ATCC11454 were investigated in pH-controlled batch culture under anaerobic conditions. Nisin production showed primary metabolite kinetics. Sucrose had the effect of regulation on nisin production, higher concentration of sucrose yielded higher biomass and nisin titer. However, the nisin production decreased when sucrose concentration was greater than 30 g/L. Lactate as the metabolic product inhibited both the cell growth and nisin production. YN/X, the nisin production yield based on sucrose consumed decreased with the increase of initial lactate concentration, which indicated that the effect of lactate on nisin production was higher than the effect on cell growth. The improvement of nisin production by adding KH2PO4 was not observed in batch culture at controlled pH 6.80.

Influencing Factors of Asymmetric Biosynthesis of R-(-)-mandelic Acid

XIAO Mei-tian;HUANG Ya-yan;SHENG Jun;MENG Chun;SHI Xian-ai;GUO Yang-hao

. 2004, 4(1): 32-36.

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R-(-)-mandelic acid is an important multifunctional pharmaceutical intermediate in the preparation of chiral drugs. A sp. strain by1 from 18 strains of Saccharomyces cerevisiae, Lactoballius, Streptococcus faecalis, Candida albicans had been screened for transforming phenylglyoxilic acid to R-(-)-mandelic acid. In this article, to study further the asymmetric bioreduction of phenylglyoxylic acid to mandelic acid by Saccharomyces cerevisiae sp. strain by1, the effect of biochemical factors on the conversion efficiency of substrate phenylglyoxylic acid and enantiomeric excess of product R-mandelic acid were investigated in detail. For some conditions tested in our experiments, the sp. strain by1 showed very high enantioselectivity toward the bioreduction of the substrates. The enantiomeric excess value of desired product R-(-)-mandelic acid reached up to 94.0%. Whereas, the conversion of substrate and the yield of product mandelic acid were influenced evidently by the environmental factors. The substrate conversion and the yield of product decreased sharply with the increase of initial substrate concentration up to 20 mmol/L. The high concentration of substrates inhibits strongly the activity of redoxase of yeast cells. Under the optimal conditions: pH 6.5, 32oC, initial concentration 15 mmol/L, absolute anaerobic cultivation 28 h, the substrate conversion rate of 97.0% and yield of product mandelic acid of 96.1% and enantiomeric excess value of R-(-)-mandelic acid of 95.1% could been obtained. This research paces the way for economic preparation of chiral R-(-)-mandelic acid.

Enzymatic Synthesis of Decanoic Acid Monoglycerides

MA Qing-yi;CHEN Hong;DU Yi;XU Ping

. 2004, 4(1): 37-41.

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Decanoic acid monoglyceride was synthesized by esterification of glycerol with decanoic acid. The effects of molar ratio of glycerol to fatty acid, reaction temperature, content of water and enzyme ratio over total weight on the reaction were studied. The optimum reaction conditions were confirmed to be 50oC, mole ratio of substrates 1:1, enzyme ratio over total weight 0.5%, and the purity of monoglyceride product in the reaction mixture was more than 70%. The advantage of the process includes simple procedure, high product content, and gentle reaction conditions.

Growth of Thiobacillus ferrooxidan in High Concentration Ferrous Ion Culture Medium

XIE Hai-yun;LIU Zhong-hua;ZHOU E

. 2004, 4(1): 42-46.

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The growth behavior of Thiobacillus ferrooxidan (T.f.) in high concentration ferrous ion solution was studied and the change of pH, potential and oxidation of ferrous ions in the solution were also investigated. It is found that T.f. can grow normally under the conditions of [Fe2+]<70 g/L, pH=1.6~2.0 and suitable inoculum of 10%. The final bacteria density after 10 d culture may be up to (0.8~31.6)′107 cell/ml.

Monte Carlo Simulation on the Morphology of Diblock Copolymer Melts Containing

HUANG Yong-min;LIU Hong-lai;HU Ying

. 2004, 4(1): 47-52.

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The morphology of diblock copolymer melts containing solid particles is simulated by the Monte Carlo method based on bond length fluctuation and hole diffusion algorithm at cubic lattice model. This work is focuses on the influence of solid particle size, selective interaction between the solid particle and the segment of copolymer and composition of diblock copolymer chain on the morphology of copolymer melts. It is shown that selective adsorption interaction of solid particle on copolymer makes against lamellar structure, but makes for cylindrical or netlike structures. The existence of inertia solid particles with modest size (comparative to the block length in diblock copolymer) is propitious to the formation of lamellar structure. Whether diblock copolymer melts contains solid particles or not, the increase of symmetry of copolymer chain is favorable to the lamellar morphology.

Influence of Catalyst Type and Regeneration on Upgrading of Crude Bio-oil through Catalytical Thermal Cracking

GUO Xiao-ya;YAN Yong-jie;LI Ting-chen

. 2004, 4(1): 53-58.

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Catalysts, such as HZSM-5(Si/Al=50), HZSM-5(25), zeolite 5A, CaHZSM-5(50), ZnHZSM-5(50), and Kaolin were used in upgrading of crude biomass oil from pyrolysis in a fixed-bed reactor under atmospheric pressure, in order to investigate the effects of catalyst type on the yield of desired product. A blank test was carried out in a bed of inert packings to determine the extent of non-catalytical thermal cracking. The gas produced in the reaction was analyzed by the chemical absorption method. Among those catalysts, HZSM-5(50) gave the highest yield of the desired organic distillate while Kaolin gave the least formation of coke. Regeneration of deactivated HZSM-5(50) was studied. In terms of yield of organic distillate and formation rate of coke, the catalytic activity did not change much during the first 3 times of regeneration.

Suppressing the Impedance Rise of LiNi0.8Co0.2O2/Graphite Cells by Al, Ti and Mg Doping

CHEN Chun-hua;XIE Song;LIU Jun;Amine K

. 2004, 4(1): 59-63.

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The research on utilizing lithium-ion batteries with LiNi0.8Co0.2O2-based cathode for hybrid electric vehicles is intensively underway in several national laboratories of US Department of Energy. The impedance of LiNi0.8Co0.2O2/graphite lithium-ion cells is observed to experience a substantial rise during accelerated calendar life storage, due mainly to the significant increase of the interfacial resistance on the cathode side. By means of electrochemical measurements and AC impedance spectroscopy, it is found that doping the LiNi0.8Co0.2O2 cathode with small amount of Al, Ti and Mg can effectively suppress this impedance rise. Possible mitigation of oxidizing ability of Ni4+ due to Al, Ti and Mg doping is proposed to achieve this impedance stabilization.

Kinetics of Sawdust Hydrolysi with Dilute Hydrochloric Acid and Ferrous Chloride

YUAN Chuan-min;YAN Yong-jie;REN Zheng-wei;LI Ting-chen;CAO Jian-qin

. 2004, 4(1): 64-68.

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With dilute hydrochloric acid as catalyst and promoted by ferrous chloride, hydrolysis of waste sawdust to produce monosaccharides was conducted by using an one-step method in a batch-wise operation reactor. Based on the model of first order consecutive irreversible reactions, the kinetics equation incorporating the term of catalyst concentration was obtained that is suitable for describing the hydrolysis of sawdust. Activation energies were calculated for hydrolysis of sawdust and decomposition of monosaccharides.

Review of Research on the Dissociation Kinetics of Gas Hydrate

LIN Wei;CHEN Guang-jin

. 2004, 4(1): 69-74.

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The research on the dissociation kinetics of gas hydrate is reviewed. The intrinsic dissociation models and effects of heat transfer and mass transfer on the dissociation are elaborated. The dissociation in application to natural gas storage and transportation, porous media and hydrate reservoir is also introduced. Significance of the study on hydrate dissociation kinetics and emphasis of future work are discussed.

Review on Fabricating YSZ Electrolyte Film for SOFC

FAN Bao-an;ZHU Qing-shan;XIE Zhao-hui

. 2004, 4(1): 75-83.

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Solid Oxide Fuel Cell (SOFC) is a promising technique for generating electricity with merits of high efficiency and low pollution. Yttria-stabilized zirconia (YSZ) is the most commonly used electrolyte material for SOFC. The preparation of high quality YSZ electrolyte film, thin but gas-tight, on porous cathode or anode is crucial to the fabrication of SOFC. This paper reviews several different methods for fabricating YSZ electrolyte film, which are generally classified as three groups: gas phase, liquid phase and solid phase methods. The advantages and disadvantages of each method and its application are discussed and then, the future development trends of fabricating YSZ electrolyte film for SOFC are analysed.

Development of Preparation for Ordered Mesoporous Silica Solid Materials

WANG Xu-hua;ZHANG Yu-chuan;QIAN Jia-sheng

. 2004, 4(1): 84-89.

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Ordered mesoporous silica (silicon dioxide) solid is a kind of new carrier material, used to prepare nanometer structure material by many such researchers. This paper has summarized the advances in the preparation of mesoporous solid materials, covering mainly the effects of different reaction system and media on mesopore ordering, mesopore diameter, mesoporous silica wall thickness, pore volume fractions, thermal stable etc.

Research Progress of Production of Metallic Titanium

WANG Zhi;YUAN Zhang-fu;GUO Zhan-cheng

. 2004, 4(1): 90-96.

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The principles and general situations of the traditional processes for producing metallic titanium, e.g., the Kroll, Hunter and molten electrolysis processes, are summarized and the new processes based on the formers, i.e., the EMR, Armstrong and FFC Cambridge processes are introduced, in addition, their mechanisms and characteristics are also analyzed. It is pointed out that the development trend for lowering titanium production cost is to convert the existing periodic processes for titanium sponge to continuous process for titanium powder or its alloy.

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