Table of Content

20 August 2003, Volume 3 Issue 4

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4

Assembly and Structural Characteristics of Organic Anion-pillared Hydrotalcites

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

. 2003, 3(4):  0-0. 

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The alternant submerged/unsubmerged cell culture of Saussurea medusa in a novel 1.8 L periodically submerged air-lift bioreactor was investigated. The bioreactor contains two layers of meshes. They provide support for cells in unsubmerged culture, but when being pulled slant the culture can be released by circulating medium from the meshes for submerged culture. The effects of the submerged/unsubmerged period on cell growth, biosynthesis of flavonoids and cell aggregate were studied. It was found that 5 min/4 h was the optimum submerged/unsubmerged period when the culture was carried out at air flow rate of 40 L/h and an inoculum (DW) of 2~3 g/L. After 20 d culture, the maximum biomass and production of flavonoids reached 9.6 g/L and 338 mg/L respectively, and the distribution of cell aggregates was the optimal as well.

Separation Characteristics of Binary Particulate Systems in a Vibrating Fluidized Bed

JIN Hai-bo; ZHANG Ji-yu; ZHANG Bi-jiang

. 2003, 3(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.

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)

. 2003, 3(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.

Fed-batch Cultivation of Botryococcus braunii in an Air-lift Photobioreactor

WANG Jun; YANG Su-ling; CONG Wei; CAI Zhao-ling

. 2003, 3(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.

Preparation of Organic-Inorganic Multifunctional Nanocomposite Coatings

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

. 2003, 3(4):  0-0. 

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Oxidation of para-aminophenol in supercritical water was investigated at 480~550oC, 32~38 MPa with 100%~270% H2O2 in excess. Experiments were performed in a tubular continuous flow reactor with effective volume of 13 ml. Results indicate that para-aminophenol is easily oxidized in supercritical water. The COD elimination efficiency is significantly improved as reaction temperature, pressure or residence time is increased. 98.5% COD removal was obtained in 229 s at 550oC, 38 MPa with 190% H2O2 in excess. In this case, the global kinetics for COD was 2.13 order. The activation energy was 29.3 kJ/mol.

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

. 2003, 3(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.

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

LI Wei; GAO Lian

. 2003, 3(4):  0-0. 

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A special reaction system was proposed to investigate the mechanism of the mass transfer process in membrane absorption process. The mass transfer resistance of this process was calculated by using hydrophobic PP hollow fiber, for either SO2/air–NaOH system or CO2/air–NaOH system. Different phenomena in these two systems were discussed. Since the reaction mechanism of SO2–NaOH system and CO2–NaOH system is different, SO2 and CO2 mass transfer in solution side is different. The diffusion of different ions and the concentration polarization in liquid phase boundary layer, instead of the ionization effect, was the reason of deviation in SO2 absorption process. The influences of liquid phase velocity and the concentration of absorbent were discussed in this study.

Preparation of Ultrafine a-Al2O3 Powder by Thermal Decomposition of AACH at Low Temperature

YANG Ye; WU Yu-cheng; LI Yong; CUI Ping

. 2003, 3(4):  0-0. 

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The interaction of sodium dodecyl benzene sulfonate (SDBS) with brlliant cresyl blue B (BCB) and three proteins: bovine serum albumin (BSA), myoglobin (Mb) and ovalbumin (OVA) have been investigated based on the theory that the electrostatic attraction between small molecule and biomacromolecule obeys the Langmuir isothermal adsorption. At pH 2.81, the aggregates were characterized by the microsurface adsorption ? spectral correction (MSASC) technique. Results showed that the aggregates: SDBS90×BSA, SDBS41×OVA and SDBS25×Mb at 30°C and SDBS64×BSA, SDBS35×OVA and SDBS15×Mb at 50°C are formed.

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

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

. 2003, 3(4):  0-0. 

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Two chemical manganese oxides were synthesized by oxidation of Mn(NO3)2 salts with KMnO4 under different pH values. The crystal structure and crystal pattern were characterized by mean of X-ray diffraction and X-ray scan microscope, which demonstrated that pH values determined the formation of crystal structure. The electrochemical performance of the two materials was studied by cycling voltammetry in the range -0.3~0.6 V (Hg/HgO), which indicated their capacitive behaviors. Comparison of capacitor with activated carbon as electrode material constructing asymmetric configuration to that with MnO2 constructing symmetric configuration, showed that both working voltage and specific capacitance of hybrid capacitors were increased. Galvanostatic charge/ discharge indicated that the specific capacitance of symmetry structure of electrochemical capacitor were 262 and 302 F/g, respectively, and those of asymmetry structure of electrochemical capacitor were 348 and 342 F/g, respectively. These materials possess better capability of high current discharge and cyclicity.

Research of 2D Substructure Search Program for Chemical Structure Database

LIU Bing; ZHOU Jia-ju

. 2003, 3(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

. 2003, 3(4):  0-0. 

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In view of the existing problem of the former control system of the Yangzhi Petrochemicals butadiene distillation column, voluminous plant operation data collected by DCS and simulated results from a theoretical model are pooled together and used to build the adaptive soft-sensor instrument for butadiene and alkynes contents in the distillation column top based on the BP neural network technique. Then, an inferential control system was designed according to the targets of product quality, in which the on-line estimating values of soft sensor instrument were used. As a result of increasing logic calculation in the inferential control arithmetic, the robustness of the control system is strengthened. Application of the control system to the column showed that the control system can run smoothly over a long period in worksites, and has realized the close-loop control of product quality.

Weak Ferromagnetism in Perovskite-type Bismuth Ferrite Nanoparticles

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

. 2003, 3(4):  0-0. 

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In order to overcome the influences of electrode reactions and the long distance between two electrodes on two-phase electrophoresis, a mini-multi-channel aqueous two-phase electrophoresis (mini-MATPE) equipment was designed, and the separation of phenylalanine in this equipment was investigated with dextran-polyethylene glycol-water as a working system. The influences of time, current intensity, initial solute concentration on two-phase concentration ratio, recovery ratio, total mass flux, and electric current efficiency was discussed. Based on the study, a semi-empirical correlation for predicting the maximum mass flux is suggested.

Mechanism of Extracting Zinc and Cadmium with Thiophosphoric

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

. 2003, 3(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.

Activity Interaction Coefficients in Mn-Fe-C Melts

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

. 2003, 3(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.

Preparation of Microgel by Crosslinking Partially Quaternized Poly(4-Vinyl Pyridine)

MA Guang-hui

. 2003, 3(4):  0-0. 

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For the conversion of hydrogen chloride to chlorine by catalytic oxidation, the suitable catalyst is supported CuO in which there is 12% of copper. It has high activity and its catalytic activity is kept unchanged after running for 200 h. When the process is divided into two stages, oxidative chlorination and chlorination, it is unnecessary to supply heat to the reaction and the conversion of HCl can achieve 100%. The optimal conditions for the stage of oxidative chlorination are: temperature 360~400oC, molar ratio of HCl to O2 2, weight hourly space velocity of the reactants 0.3~0.4 h–1; for the stage of chlorination, the temperature should be about 200oC.

Preparation of Al2O3-coated Nano-ZnO Composite Powder for Reducing Photocatalytic Activity

YIN Chun-lei; YUAN Fang-li; HUANG Shu-lan

. 2003, 3(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.

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

. 2003, 3(4):  0-0. 

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On the basis of our research results, this article introduced mechanism and conditions of direct-current arc plasma used for synthesis of nanoparticles, as well as variety, crystalline structure and property of the nanoparticles. According to our results, many kinds of nanoparticles such as metals, oxides, nitrides, carbides and hydrides can be produced by direct-current arc plasma. The mean particle sizes of nanoparticles are usually in the range from 10 to 200 nm, changing with production conditions and components. The production rate by using this method is 10 times or more larger than that by the conventional vapor evaporation method, so this method is suitable for industrial production of nanoparticles.

Axial Flow Pattern in a Concurrent Downflow Fluidized Bed (Downer) with Linearly Variable Superficial Gas Velocity

LIU Teng-fei; DENG Ren-sheng; WEI Fei; JIN Yong

. 2003, 3(4):  0-0. 

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Numerical simulation on the liquid–solid two-phase flow behavior within a liquid–solid loop reactor was carried out by the CFD approach. A mathematical model has been developed with the two-fluid model and the kinetic theory of dense gas for the solid phase. The calculated results reasonably explained the liquid and solid flow mechanism in the liquid–solid loop reactor and the accordance with experimental results has validated the accuracy and applicability of the model.