Table of Content

20 August 2002, Volume 2 Issue 4

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4

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

. 2002, 2(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.

Preparation of LiMn2O4 Lithium-ion Battery Cathode Material

ZHAO Ming-shu; ZHAI Yu-chun; TIAN Yan-wen

. 2002, 2(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.

Separation Characteristics of Binary Particulate Systems in a Vibrating Fluidized Bed

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

. 2002, 2(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.

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

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

. 2002, 2(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.

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

. 2002, 2(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.

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

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

. 2002, 2(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 .

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)

. 2002, 2(4):  0-0. 

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Ti/TiO2 electrodes were prepared with the polymeric precursor method (PPM). The structure and morphology of Ti/TiO2 electrodes were examined with XRD and ESEM. The voltammetric charge (q*) of Ti/TiO2 electrodes as cathode in 0.5 mol/L H2SO4 solution was investigated with cyclic voltammetry. It was found that the electrocatalytic activity of the Ti/TiO2 electrodes was affected by the structure and morphology of the Ti/TiO2 electrodes, in other words, was affected by the calcination conditions of preparing the electrodes. The value of q*in was considerably larger than that of q*out, which means that the ‘inner’ active surface area was much larger than the ‘outer’ active surface area, and ‘inner’ active surface played a main role in the electrocatalytic activity of the Ti/TiO2 electrodes.

Mechanism of Extracting Zinc and Cadmium with Thiophosphoric

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

. 2002, 2(4):  0-0. 

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In the extraction of zinc and cadmium with di-(2-ethlhexyl)-dithiophosphoric acid(D2EHDTPA)–primary amine N1923 or di-(2-ethlhexyl)-monothiophosphoric acid(D2EHMTPA)–primary amine N1923, the dependence of the percentage extraction on pH was comparatively abnormal, which was probably caused by primary amine N1923 reacting with H2SO4 and aggregating into reversed micelle. If the empirical formula of the N1923–H2SO4 adduct is expressed by (N1923)n.H2SO4, the ratio n between N1923 and H2SO4 was about 3 in most cases of our research, which might be related to stereoscopic effects. The extraction mechanism was proved as follows:M2+(a)+2BHA(o) + (2/n)SO42–(a) = MA2(o) + (2/n)(Bn.H2SO4)(o) + 2(1–2/n)H+(a) , n=3, 4, 5.

Weak Ferromagnetism in Perovskite-type Bismuth Ferrite Nanoparticles

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

. 2002, 2(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).

Assembly and Structural Characteristics of Organic Anion-pillared Hydrotalcites

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

. 2002, 2(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.

A Preliminary Study on in vitro Behaviors of Sol-Gel Derived Nano Fluorapatite/Hydroxyapatite Coatings

QU Hai-bo; SONG Chen-lu; CHENG Kui; SHEN Ge; WENG Wen-jian; DU Pi-yi; HAN Gao-rong

. 2002, 2(4):  0-0. 

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This paper accomplished the substructure search program using object oriented method and VF algorithm. The program has good performance and transplantable character. The results are correct compared with 3DFS. It is suitable to deal with large chemical structure database. And it has been applied to data mining and finding leading drugs from our Traditional Chinese Medical Database.

Concentration Polarization of Membrane Absorption Process of Acidic Gases

ZHANG Wei-dong; GAO Jian; SHI Ji-fen

. 2002, 2(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.

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

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

. 2002, 2(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.

Preparation of Organic-Inorganic Multifunctional Nanocomposite Coatings

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

. 2002, 2(4):  0-0. 

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A novel dry gas–solid–solid fluidized bed process was adopted for simultaneous high removal of SO2 and NO from flue gas of power plants combusting coal. The fine sorbent employed was porous alumina particles coated with potassium carbonate. Under different operation temperatures, the fine sorbent was continuously fed into a fluidized bed of silica sand where sorption reaction between the sorbent particles and model flue gas took place. Removal efficiencies of SO2 and NO were compared under different operation parameters including bed temperature, sorbent kind and size, mole ratios of potassium over SO2 and/or NO. The regeneration of alumina carrier were also investigated. It was found that 100% of SO2 and 92% of NO can be removed simultaneously with no ammonia injection under the typical temperature range of flue gas before entering stacks in a power plant. A great amount of data showed a strong beneficial effect of SO2 in the flue gas on NO removal. Porous alumina carrier can be effectively regenerated with distilled water for repeated sorbent preparation and further use in reaction.

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

MA Guang-hui

. 2002, 2(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.

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

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

. 2002, 2(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.

Activity Interaction Coefficients in Mn-Fe-C Melts

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

. 2002, 2(4):  0-0. 

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Nano-ZrO2 powders were prepared by the modified precipitate method under various heating treatment conditions. TEM, SAXS, BET and XRD analyses indicated that the influence of heat treatment on the performance of nano-ZrO2 is notable. Combining the experimental results and theoretical analysis, the mechanism of particles’ growth and aggregation, and the effect of heat treatment upon the change of composition, granularity and microstructure were proposed.

Effect of Cultivation Conditions on the Growth of Thiobacillus Ferrooxidans and Ferrous Iron Oxidation in an Airlift Reactor

LUO Lin; KANG Rui-juan; MA Xiao-nan; CAI Zhao-ling

. 2002, 2(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 and Investigation of Nanoporous Super Thermal Insulation: Silica Aerogels

SHEN Jun; ZHOU Bin; WU Guang-ming; DENG Zhong-sheng; NI Xing-yuan; WANG Jue

. 2002, 2(4):  0-0. 

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Al2O3-coated nano-ZnO composite powder was obtained by coating precursor in slurry of basic zinc carbonate. The composite powder was examined by UV-VIS and TEM, and its photocatalytic activity was determined by photooxidation of castor oil illuminated under a high pressure mercury lamp. The composite particles are about 50 nm, and coated homogeneous film is 3~5 nm thick. The composite powder has nice ultraviolet- adsorption as good as un-coated nano-ZnO and its photocatalytic activity is reduced significantly. Compared with coating the calcined product ZnO powder surface, less steps are required in this coating process. As a result, the agglomeration during preparation steps is avoided.