Table of Content

20 August 2001, Volume 1 Issue 4

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4

Numerical Simulation of Flow Behavior in a Liquid–Solid Loop Reactor

WANG Yang; GAO Jin-sen; XU Chun-ming; LIN Shi-xiong

. 2001, 1(4):  0-0. 

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A one-dimensional model is established to simulate the axial flow patterns in a downer reactor. Based on the gas–solid continuity equation and the momentum equation, the model takes the variation of superficial gas velocity in the downer into account. The gas and solid velocity and the voidage distribution is emphatically studied. The simulation results show that there exists a remarkable disparity of axial flow pattern between variable superficial gas velocity and fixed gas velocity conditions. The linearly variable superficial velocity condition is more close to a downer reactor in practical operation.

Determination of Interfacial Parameters of Copolyamide Membrane Material by HPLC

ZHANG Xiu-zhen(张秀真);GAO Su-lian(高素莲);CHEN Jun(陈均

. 2001, 1(4):  0-0. 

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Based on the growth characteristics of Thiobacillus ferrooxidans in bioleaching systems, an airlift reactor was constructed to cultivate the bacteria. Leathen medium and 9K medium under different conditions were used to study the growth of Thiobacillus ferrooxidans, Fe2+ oxidation rate, dissolved oxygen and their relationship in the airlift reactor. The influence of cultivation conditions on the growth of the bacteria was investigated by monitoring dissolved oxygen and Fe2+ oxidation rate.

Preparation of Organic-Inorganic Multifunctional Nanocomposite Coatings

CHEN Yun-fa; WANG Rui-ming; WU Zhen-jiang; XIE Yu-sheng

. 2001, 1(4):  0-0. 

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Activity Interaction Coefficients in Mn-Fe-C Melts

CHEN Er-bao; DONG Yuan-chi; GUO Shang-xing

. 2001, 1(4):  0-0. 

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Bioleaching of Nicopyrite was studied and the following conclusions were drawn from the experiments: (1) The bacteria attached on the surface of the minerals had the most important contribution to the dissolution of Nicopyrite, the free bacteria in the solution had minor contribution; (2) Fe2+ was mainly oxidized by free bacteria in the solution; (3) The incomplete oxidation of S can lead to rising of pH value in solution.

Electrocatalytic Activity of Ti/TiO2 Electrodes in H2SO4 Solution

WANG Ya-qiong(王雅琼);TONG Hong-yang(童宏扬);XU Wen-lin(许文林)

. 2001, 1(4):  0-0. 

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Combustion synthesis of Al2O3-TiC-ZrO2 composites by reaction in the Al-TiO2-C-ZrO2 system is a new method with advantages of simplicity and efficiency. In the present work, the adiabatic combustion temperature of this complex system is calculated and the possible combustion products are discussed by a new approach of overlapped phase stability diagrams (PSD) of Al-O-N, Ti-O-N, Zr-O-N and C-O-N systems. Thermodynamic analysis shows that the adiabatic combustion temperature of the Al-TiO2-C-ZrO2 system with the addition of 10% ZrO2 is 2327 K which is the melting point of Al2O3, and the combustion product is a mixture of Al2O3-TiC-ZrO2. Microstructure and chemical composition of the combustion products are studied by X-ray diffraction analysis (XRD) and transmission electron microscope (TEM) respectively.

Preliminary Study on the Carbonation of K2CrO4 for Recovery of Potassium Alkali

YANG Ren-chun; HE Li-hui; LI Zuo-hu; ZHANG Yi

. 2001, 1(4):  0-0. 

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The effects of the K2CrO4 concentration, CO2 pressure and temperature on equilibrium concentration of KHCO3 were investigated respectively during the K2CrO4 carbonation with kinetic equations derived. Experimental results showed that the equilibrium concentration of KHCO3 was above 225 g/L under the optimal conditions of 40% K2CrO4 concentration, 0.6 MPa CO2 pressure and 18oC temperature. The kinetic equation was derived and its parameter was confirmed by experimental data .

Research of 2D Substructure Search Program for Chemical Structure Database

LIU Bing; ZHOU Jia-ju

. 2001, 1(4):  0-0. 

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The structure and electrochemical properties of Zr0.9Ti0.1(Ni,Co,Mn,V)2.1 alloys prepared by both the melt-spinning method and the conventional induction melting were investigated. XRD studies showed that Zr0.9Ti0.1(Ni,Co,Mn,V)2.1 alloys at as-cast, melt-spinning and annealing were all the face center cubic structure with Laves C15 phase, and the higher the melt-spinning rate, the more the amorphous content. The electrochemical measurements showed that melt-spinning alloys had better activity, low discharge capacity (<270 mA×h/g); but after annealed, the alloys are activated completely with 30 cycles, the capacities about 340 mA×h/g were higher than those of the as-cast and melt-spinning alloys; the annealed alloys had better cycle stability than that of the as-cast alloy, and the higher the melt-spinning rate, the more stable the alloy became.

Preparation and Tribological Investigation of PbS-TiO2 Nanocomposite Thin Films

CHEN Yun-xia; WANG Bo; LIU Wei-min

. 2001, 1(4):  0-0. 

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The preparation of LiMn2O4 by the solid reaction multiple sinter method was studied, in which the sintered material was smashed, ground and pelleted between two successive sintering steps. The optimum technological condition was obtained through orthogonal experiments by L25(55) and DTA analysis. The result was that the order of factors influencing the electrochemical property of synthesized LiMn2O4 were the third sintering temperature, oxygen flowrate, the second sintering temperature, molar ratio of lithium/manganese, homothermal time in decreasing importance. The electrochemical testing results of LiMn2O4 experimental battery showed that specific discharge capacity reached 140 mA·h/g and the persisting time up to 8 h at 3V-discharge plateau. With the standpoint of structural chemistry, the charge-discharge mechanism of spinel structure of LiMn2O4 material was analyzed and the reason of Jahn-Teller domio effect was also suggested.

Silica Nanofibers Enwrapped with Well-organized AgCl Nanoparticles

LI Yong-jun; LIU Chun-yan; ZHANG Zhi-ying

. 2001, 1(4):  0-0. 

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Bacteriocin nisin was isolated and purified in temperature-induced aqueous two-phase systems using the capacity of extracting hydrophobic proteins of TritonX-114. The concentrations of sodium chloride and TritonX-114 which can form the aqueous two-phase systems were optimized by the response surface method. The full-factorial design was used to assess the main effects of factors and determine the path of steepest ascent to the optimal region of the aqueous two-phase system composition. The optimum concentrations of TritonX-114 and sodium chloride were then easily determined by using a central composite design and were found to be 3.27% of TritonX-114 and 0.85 mol/L sodium chloride. The recovery and purification factor were 92% and 9.05 respectively under the optimum conditions.

Cracking of Thiophene in Coke-oven Benzene over the HZSM-5 Zeolite Sieve

XU Xin; LUO Guo-hua; ZHANG Guo-ying; YANG Chun-yu; GUO Xin-wen

. 2001, 1(4):  0-0. 

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Removal of thiophene from coke-oven benzene over the HZSM-5 zeolite was investigated. The reaction temperature and pressure are the keys to the catalytic activity and the activity stability of HZSM-5 catalyst, over which thiophene is converted into sulfide hydrogen. At the reaction conditions of temperature 320~380oC, WHSV 4.0~12.0 h-1 and reaction pressure 2.0~6.0 MPa, HZSM-5 catalytic activity and stability are excellent, and the rate of removal of thiophene from coke-oven benzene is more than 99%.

Effect of TiO2 Content on the Densification, Microstructure and Dielectric Properties of ZrxTi1-xO2 Microwave Dielectric Ceramics

ZHANG Shu-xia; LI Jian-bao; CAO Jun; ZHANG Bo; ZHAI Hua-zhang

. 2001, 1(4):  0-0. 

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Ceramic samples of ZrxTi1-xO2 with x=0.40~0.60 were prepared from powders made by the coprecipitation method. The densification, microstructure and dielectric properties of sintered bodies were investigated. The results indicated that the composition affected the densification. The increase of TiO2 content led to larger gain size and lower relative density. The dielectric properties of sintered bodies were affected by the relative density and the composition. As the relative density increased, both the dielectric constant and the quality factor increased. The dielectric constant and the quality factor were primarily influenced by the composition and virtually independent of relative density for densities greater than 90% theoretical. The effects of relative density could be neglected. With the increase of TiO2 content, the dielectric constant increased, whereas the quality factor decreased.

Weak Ferromagnetism in Perovskite-type Bismuth Ferrite Nanoparticles

HE Hai-ying; KOU Xin-li; LI Jian-gong

. 2001, 1(4):  0-0. 

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The effects of modifiers on the extraction of cobalt(II) and iron(II) with tertiary amine were investigated. It was found that additional modifiers, oxygen-containing organic compound(HA3), had the synergism with tertiary amine for cobalt extraction and also changed the property of the iron extraction. The loaded iron(II) can not be stripped by dilute acidic solution. Cobalt(II) and iron(II) could be separated by using scrubbing and stripping. The new technology of separation of cobalt(II) and iron(II) extractive, with tertiary amine from chloride solution was proposed, which avoids the preoxidation of iron(II).

Self-assembly of the [60]fullerene-substituted Oligopyridines on Au Surface

LIU Hui-biao; LI Yu-liang; LUO Hong-yuan; ZHU Dao-ben

. 2001, 1(4):  0-0. 

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PEG-modified Fe3O4/PVA magnetic polymer micropheres were synthesized and characterized by microphotography, laser diffraction particle analysis, FT-IR spectroscopy etc. The results indicate that the size of micropheres presents a Gaussian distribution, and PEG could be immobilized to PVA magnetic microspheres. The magnetic polymer microspheres are stable in a wide range of pH and temperature. The contents of PEG and Fe3O4 were about 190 mg/g and 100 mg/g in the microspheres respectively. These properties make the microspheres promising in applications in the field of catalysis and biotechnology.

Numerical Simulation of Electromagnetic Stirring Flow of Metal Pad in Aluminum Reduction Cells

ZHOU Ping; ZHOU Nai-jun; MEI Chi; JIANG Chang-wei; CAI Qi-feng

. 2001, 1(4):  0-0. 

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Delivery of catalyst particles by a screw feeder at the inlet of a downer in a hot model was studied, and the effects of pressure difference, downward wind, temperature on feeding rate were investigated. Experimental results show that the feeding rate can be flexibly controlled by adjusting the pressure in the catalyst feeding tank.

Preparation of Ultrafine ZrO2 by the Air Plasma Oxidation-Thermal Decomposition Method

MA Bing; DOU Ming-min

. 2001, 1(4):  0-0. 

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Ultrafine ZrO2 particles were prepared by the oxidation-thermal decomposition of Zr2O(CO3)×xH2O and the spray-ICP technique of zirconium salt solution in an inductively coupled plasma. Their particle diameters ranged from 0.1~0.3 mm and 5~60 nm respectively. X-ray diffraction analysis indicated that the major phase is tetragonal and cubic ZrO2, the minor one is monoclinic ZrO2, the major is of metastable structures.

Mechanism of Extracting Zinc and Cadmium with Thiophosphoric

ZHANG Da-li; KE Jia-jun; LU Li-zhu

. 2001, 1(4):  0-0. 

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A new anion-exchange chromatographic method was developed for the separation of cobalt from zinc, cadmium and copper. Experimental results showed that, in a 2 mol/L sodium chloride, 0.1 mol/L sodium sulphite and initial pH 4.5 solution, copper(II) was reduced to copper(I) and pH was decreased to 4.0. As the solution was driven through a 201′7 anion-exchange chromatographic column, zinc, cadmium and copper were effectively separated and the loss of cobalt was about 0.7%. This method is simple, rapid and effective, and has been successfully applied to the separation of cobalt in leach liquor of a zinc plant residue after sulphated calcination.

Effect of Calcium and Magnesium on the Photocatalytic Oxidation of Humic Acid in Water over TiO2

FAN Cai-mei; SUN Yan-ping

. 2001, 1(4):  0-0. 

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The feasibility study on degradation of organic phosphorous pesticide by photo-catalysis at the surface of titanium dioxide thin films was carried out. The films were prepared over different substrates by lower pressure chemical vapor deposition. The factors influencing the degradation rate of organic phosphorous pesticide were investigated. It was found that the optimal conditions for photo-catalytic conversion are copper wire as the substrate, annealing the film at 450oC and using the film as quickly as possible after it is deposited. It is also shown that when the pH of solution is equal to 2 and nitric acid is used to adjust pH, the degradation conversion is higher.

Improvement of the Fermentation Productivity of a New Antibiotic AGPM by Orthogonal Design Experiment

SHI Bing-xing; ZHAO Hong; LIU Xi-peng; YUAN Ying-jin; HU Zong-ding

. 2001, 1(4):  0-0. 

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The effects of medium composition on the activity of a new antibiotic APGM was studied by orthogonal design experiment. It seems that nitrogen source presented the most significant effect on the production of AGPM and that higher ratio of carbon to nitrogen was beneficial. It was concluded that the fermentation activity was increased by 18.9 times to 1562.2 u/ml under the optimal conditions as the medium was composed of glucose 5 g/L, corn starch 40 g/L, soybean meal 16 g/L, corn steep liqour 2 ml, K2HPO4 1.0 g/L, MgSO4·7H2O 0.5 g/L, NaCl 0.5 g/L and amylase 0.05 g/L.

Synthesis and Low-temperature Sintering of Nano-sized HAp Powders

LI Wei; GAO Lian

. 2001, 1(4):  0-0. 

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Solvent extraction and stripping of KAu(CN)2 from alkaline solution with cetyltrimethylammonium bromide (CTAB)/hexanol/heptane using 198Au tracer was investigated. Various parameters, such as Au(I) concentration in aqueous phase, concentrations of halogen ions, NH4SCH and thiodiethylene glycol in stripping solution as well as the relationship between water and Au(I) concentrations in organic phase, in the forward and backward extraction of Au(I) were studied. The results show that water content decreases significantly with the increase of Au(I) concentration in the organic phase. About 98% Au(I) extracted into organic phase can be back extracted with pure thiodiethylene glycol as the stripping agent. Most of Au(I) (~93%) in the organic phase can be stripped into the aqueous phase with high concentration of NH4SCN(>3.0 mol/L) or KI (>2.0 mol/L).

Metabolism Kinetics of Glucose in Anchorage-dependent Cell Cultures

SUN Xiang-ming (孙祥明);ZHANG Yuan-xing (张元兴)

. 2001, 1(4):  0-0. 

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The kinetic model of glucose metabolism was established and successfully applied to batch cultures of rCHO and rBHK cells. It was found that a large amount of glucose was utilized for cell maintenance, and the overwhelming majority of maintenance energy from glucose was by its anaerobic metabolism in both rBHK and rCHO cell cultures. The overall maintenance coefficients from aerobic metabolism were 1.9′10-13 mmol/(cell·h) for rCHO cells and 7′10-13 mmol/(cell·h) for rBHK cells. In addition, all GO/T and EO/T gradually increased with the same trend as the cell growth in the culture of both rCHO and rBHK cells. The overall molecule yield coefficients of lactate to glucose were 1.61 for rCHO cells and 1.38 for rBHK cells. The yield coefficients of cell to glucose were 4.5′108 cells/mmol for rCHO cells and 1.9 ′108 cells/mmol for rBHK cells, respectively.

Experiment on Degradation of Phenol Waste Water with Pseudomonas sp.

QIAN Yi-zhong; ZHANG Peng; TAN Tian-wei

. 2001, 1(4):  0-0. 

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Strains were isolated from coking plant polluted soil. A strain which degraded phenol was obtained by screening and acclimatizing, and was identified as Pseudomonas sp. After optimization of conditions, the degradation of phenol is up to 100%. The suitable conditions for degradation of phenol are pH=6.79 and T=37oC and the kinetics of the degradation was also explored.

Assembly and Structural Characteristics of Organic Anion-pillared Hydrotalcites

LI Dian-qing; FENG Tao; Evans D G; DUAN Xue

. 2001, 1(4):  0-0. 

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The gelcasting of Al2O3 was accomplished by means of the gelling reaction of monofunctional acrylamine and bifunctional N, N￠-methylenebisacrylamide. The effects of dispersant concentration, pH value and agitation time on the viscosity of the slurries were investigated. In this process, TiO2 was used as the sintering aid, and its effects on the densification and quality of obtained ceramics were observed. The results show that 97% of the relative density was achieved by ambient pressure sintering at 1300oC when 5% TiO2 was added into ceramics.

Preparation of Silicon-based Nanoscale b-SiC Quantum Dot Array

WU Xing-long; GU Yi; BAO Xi-mao

. 2001, 1(4):  0-0. 

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Separation characteristics of 13 kinds of binary mixtures were investigated in a vibrating fluidized bed. A separation index, which was given by Williams through comparing the jetsam concentration in the upper and lower layers, was suggested. According to the effects of vibrating parameters and operating conditions on the separation index, the optimum vibrating parameters were obtained. From experimental results, the criterion of demarcating mixing/separation regions, which was defined by Zhang et al, was modified.

Degradation of Pesticide by Photo-catalysis with Titanium Dioxide Thin Films

WU Zheng-huang;WANG Bao-feng

. 2001, 1(4):  0-0. 

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The feasibility study on degradation of organic phosphorous pesticide by photo-catalysis at the surface of titanium dioxide thin films was carried out. The films were prepared over different substrates by lower pressure chemical vapor deposition. The factors influencing the degradation rate of organic phosphorous pesticide were investigated. It was found that the optimal conditions for photo-catalytic conversion are copper wire as the substrate, annealing the film at 450oC and using the film as quickly as possible after it is deposited. It is also shown that when the pH of solution is equal to 2 and nitric acid is used to adjust pH, the degradation conversion is higher.

Boileaching of Ni, Cu and Co from a Low-grade Ni–Cu Sulfide Ore

CHEN Quan-jun; FANG Zhao-heng

. 2001, 1(4):  0-0. 

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Bioleaching of Ni, Cu and Co from the Jinchuan low-grade Ni–Cu–Co sulfide ore has been investigated with aerated leaching, agitated leaching with air bubbling, and column leaching respectively. The highest recovery was achieved in the aerated leaching. Leaching 20 d with pulp density of 15%, the leached Ni, Cu and Co were 95.4%, 48.6% and 82.6% respectively. By agitated leaching with air bubbling for 14 d at the pulp density of 25%, the leached Ni, Cu and Co were 80.2%, 45.2% and 78.4% respectively. With column leaching for 49 d, the leached Ni, Cu and Co were 48.5%, 37.5% and 33.6% respectively.