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The Chinese Journal of Process Engineering 2007 Vol.7 Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Axial Distributions of Solids Density in Annular Flow Mixing Unit of Combustor for Petroleum Coke YAN Chao-yu;LU Chun-xi;WANG De-wu;GAO Jin-sen;ShI Ming-xian    2007, 7 (1): 1-7.   Abstract （2410）      PDF （227KB）（845）       Knowledge map    Save A large-scale cold experimental equipment which can adapt to combustion demands of petroleum coke was established by using the combined structure of gas-solid annular flow and riser transporter reactor. The pressure gradients of air-sand two-phase flow along the axial direction of the annular flow unit were measured by differential pressure transmitters under different operation conditions. The axial distributions of solids density in two regions of the annular flow mixing unit, namely internal annular and external annular regions, were investigated. The results show that the axial distributions of solids density in the internal annular region have two modes, namely the bottom dense phase and the upper turbulent flow diffusion phase. The solids flux has little effect on the density distributions in the bottom dense region, but significant effect on the upper turbulent flow diffusion region. The solids density in the whole internal annular region decreases with increasing the superficial gas velocity. The axial distribution of solids density in the external annular region is directly relative to the superficial gas velocity, solids flux in the internal annular region and the solids dense phase level in the external annular region. The empirical models for axial distributions of solids density in the internal and external annular regions have been established based on the experimental data. The model predictions are in good agreement with the experimental data. Related Articles | Metrics Select Numerical Simulation of a Packed Bed Reactor with Novel Internals-I. Flow Field and Residence Time Distribution of Gas Phase ZHANG Xue-jia;CHENG Yi;HAN Ming-han    2007, 7 (1): 8-13.   Abstract （2564）      PDF （284KB）（776）       Knowledge map    Save A mathematical model describing the gas flow in a packed bed with novel internals was established, which considered the combined geometry of a packed bed of particles and the gas passages with baffles. Computational fluid dynamics (CFD) simulation was carried out to study the flow pattern and the residence time distribution (RTD) of gas phase under different operating conditions and reactor geometries. The experimental data of the pressure drop validated the CFD simulation at the reactor scale. The detailed flow field inside the reactor was disclosed with the simulation, which showed the zig-zag flow behavior of the gas phase through the packed bed and the gas passages. The gas did not by-pass the system because the reactor remained to be the configuration with multiple compartments connected in series. The design of the internal imposed strong influence on the gas flow field and the corresponding RTD, which allowed a large room for optimizing the packed bed with internals. Related Articles | Metrics Select Characteristics of Fluid Flow and Particle Suspension in a Solid-Liquid Draft-tube Stirred Tank CHEN Wen-min;HUANG Xiong-bin;GAO Zheng-ming    2007, 7 (1): 14-18.   Abstract （1754）      PDF （221KB）（906）       Knowledge map    Save The three-dimension velocity distribution of single liquid phase, solid concentration distribution and particle off-bottom suspension characteristics in the liquid-solid phases were systemically investigated in a draft-tube stirred tank of 0.8 m diameter. The results showed that the axial velocity of liquid phase was far larger than radial and tangential velocities inside and outside the draft tube. And there was a second circulation zone close to the outside wall of the draft tube. The shallow conical bottom leads to a critical just off-bottom suspension impeller speed (NJS) at least 14% lower than that in the flat bottom. As expected, NJS increased as the solid concentration increased. NJS decreased slightly as the solid concentration exceeded 50%. The homogeneity of vertical solid concentration distribution was enhanced with the increase of solid concentration. The results are of importance to the optimization of industrial draft-tube stirred reactors. Related Articles | Metrics Select Experimental Study on Characteristics of Gas-Solid Mass Transfer and Reaction in a Downer ZHANG Yong;FAN Chui-gang;LU Xue-song;LI Song-geng;SONG Wen-li;YAO Jian-zhong;LIN Wei-gang    2007, 7 (1): 19-23.   Abstract （1676）      PDF （248KB）（844）       Knowledge map    Save Mass transfer and reaction characteristics in a gas-solid cocurrent down flow circulating fluidized bed (downer) are experimentally studied by catalytic decomposition of ozone. The profiles of solids and ozone concentrations are measured in a downer reactor with a diameter of 0.09 m and a height of 8.2 m while ozone decomposition catalyst is circulated in the bed. The experimental results show that about 45% of ozone is decomposed in the acceleration zone of the downer reactor which is more than 90% of total ozone decomposed in the downer. Ozone conversion rate in the downer increases from 50% to 55% when the solids circulating rate increases from 2.77 to 6.58 kg/(m2×s). A plug flow mass transfer model is established and correlation between effective mass transfer coefficient and operation parameter is obtained. Related Articles | Metrics Select Experimental Study and Numerical Simulation of Gas-Liquid Flow in a Stirred Tank with a New Multiple Impeller SONG Yue-lan;GAO Zheng-ming;LI Zhi-peng    2007, 7 (1): 24-28.   Abstract （1630）      PDF （236KB）（917）       Knowledge map    Save The fluid flow in a gas-liquid stirred tank of 0.476 m diameter with triple impellers was experimentally investigated and numerically simulated. The Eulerian-Eulerian formulation, standard k-e turbulent model and multiple frames of reference (MFR) method were used in the simulation. The newly developed four-half-elliptical-hollow-blade disk turbine (HEDT) was used as the bottom impeller to disperse the incoming gas, and two upward-pumping four-wide-blade hydrofoil (WHU) impellers were used as middle and top impellers to insure the homogenous mixing from the top to bottom in the tank. The power number, gassed power demand and overall gas holdup predicted by CFD are in good agreement with the experimental data. The local gas holdup distribution is mainly controlled by the flow field. There is a region with very high local gas holdup just above the top impeller and near the tank wall, which is in agreement with the literature. The results are of importance to the optimization of industrial stirred tank reactors. Related Articles | Metrics Select NOx Emission Characteristics of Methane/Oxygen-enriched Air Jet Diffusion Flames LU Guan-jun;ZHAO Dai-qing;YANG Hao-lin;YANG Wei-bin    2007, 7 (1): 29-33.   Abstract （1665）      PDF （273KB）（719）       Knowledge map    Save The influence of oxidizer velocity on NOx emission characteristics of methane/oxygen-enriched air coflow jet diffusion flames was investigated experimentally. By means of investigating the radial temperature distributions of flames, flame configurations and the flow fields of diffusion combustion nearby the jet exit, the NOx emission characteristics were analyzed under different conditions. The results indicated that EINOx, NOx emission index, decreased with the increase of oxidizer velocity when keeping the fuel and oxidizer flowrate constant, and that small flame could keep lower EINOx level when keeping oxygen concentration and excess air coefficient a constant. Related Articles | Metrics Select Numerical Simulation of Producing Aluminum Foam by Air Injecting and Melt Stirring LIU Hong;XIE Mao-zhao;WANG De-qing    2007, 7 (1): 34-38.   Abstract （1436）      PDF （653KB）（643）       Knowledge map    Save Production of aluminum foam by air injecting into molten aluminum composites under mechanical stirring has been investigated. A two-dimensional computational two-fluid model incorporated with the multi-reference frame method is used to predict the gas-liquid flow in a horizontally axial stirred vessel. Turbulence effect is simulated with a RNG k-e model. The influences of gas inlet velocity and impeller rotational speed on bubble rising velocity and local gas volumetric fraction are examined. Furthermore, volumetric average of total gas fraction is predicted by volume integration. Computational results show a qualitative agreement with experimental data from the literature. Related Articles | Metrics Select Comparison of Activating Performance of Activators in Membrane Gas Absorption LU Jian-gang;ZHENG You-fei;CHEN Min-dong;HE Du-liang;ZHAO Xiao-li;ZHANG Hui    2007, 7 (1): 39-43.   Abstract （2487）      PDF （222KB）（644）       Knowledge map    Save Piperazine (PZ) and 2-amino-2-methyl-1-propanol (AMP) as activators were added into methyldiethanolamine (MDEA) to form complex aqueous solutions, respectively. Mass transfer performance of CO2 absorption into the complex aqueous solutions in membrane contactors was studied. The effects of various factors, such as flowrates of gas and liquid, CO2 concentration of feed gas, absorbent concentrations of the solutions, CO2 loading in the solutions, configuration of membrane, and structures of modules on overall mass transfer coefficients of membrane contactors were investigated. Emphatically, the enhancement of mass transfer in membrane contactors was evaluated by means of comparison of chemical activation of sterically hindered amine AMP and multi-amino PZ in the complex solutions. The results show that multi-amino PZ has higher activation than sterically hindered amine AMP in complex solutions. The enhancement of PZ to mass transfer is higher than that of AMP in membrane contactors. The effect of hydrodynamics on mass transfer is limited. Chemical activation of activators is the key influential factor on mass transfer. Reaction kinetics plays a significant role in mass transfer. Related Articles | Metrics Select Modification of PDMS Membrane by Organo-montmorillonite for Pervaporation of Acetic Acid over Water XU Guo-qiang;YU Jiang;WANG Kang;LIU Hui-zhou    2007, 7 (1): 44-48.   Abstract （1510）      PDF （425KB）（739）       Knowledge map    Save An organo-montmorillonite filled polydimethylsiloxane membrane was developed for recovering acetic acid from its dilute solution by pervaporation. The filled membrane was prepared by cross linking reaction in solution using cetyltrimethylammonium bromide (CTAB) pillared montmorillonite. XRD and SEM were applied to characterize the filled membrane morphology. The results showed that the filled membrane with organoclay silicate layers not only showed the most optimal thermal stability but also exhibited the highest separation factor for the pervaporation of acetic acid over water when the filler content was around 7.4%(w). A possible mechanism was proposed that the enhanced selectivity and permeability were derived from the effect of permeable reactive passageways for adsorption-transport-desorption because of the ordered nano-layered structure and hydrophobic capacity of organo-montmorillonite in the hybrid membrane. Related Articles | Metrics Select Adsorption of Polystyrene Diethanolamine Resin for Cupric Ion WANG Yan-qin;WEI Rong-qing;LIU Xiao-ning;LIU Ying    2007, 7 (1): 49-53.   Abstract （1707）      PDF （211KB）（773）       Knowledge map    Save The new polystyrene diethanolamine resin (PS-Acyl-DEA) was synthesized by the reaction of diethanolamine (DEA) with chloracetylated polystyrene (PS-Acyl-Cl) instead of chloromethylated polystyrene (PS-CH2-Cl) which is commonly used. The adsorption kinetics and isotherms of obtained product for cupric ion were studied. The results showed that the adsorption capacity increased as the increasing loading of the product and was steady in the environment with the pH values between 5.6 and 10.5. The Cu2+ adsorption quantity was 3.79 mmol/g and the adsorption rate of the resin to cupric ions was up to 93.8%. Related Articles | Metrics Select Thermodynamics and Kinetics of Ni-P-C-O System for Electroless Plating LIU Shao-you;WEN Zheng-kang;JIANG Tian-zhi;YANG Hong-yun    2007, 7 (1): 54-58.   Abstract （2639）      PDF （216KB）（615）       Knowledge map    Save Changes of nickel ion and butynediols (BOZ) concentration in electroless plating Ni-P-C-O solution were determined by UV-Vis spectrophotometry with high performance liquid chromatography. Thermodynamic functions, such as DGTf, DH and DS, and kinetic parameters of the Ni-P-C-O alloy chemical plating process were obtained. The reaction mechanism between nickel ion and butynediols in the electroless plating process was analyzed. The results show that the change of BOZ concentration is a quasi first-order reaction, the change of the nickel ion concentration is related to the BOZ density, and this change belongs to a higher order reaction. The reaction rate equation was determined as dC/dt=-8.585′10-4+1.188′10-4t-4.62′10-6t2+5.8′10-8t3-2.3′10-11t4. The activation energy of this process decreases as temperature increases, and it decreases with the BOZ concentration as 64~123 mg/L, it increases with the BOZ concentration as 123~240 mg/L. The DST value is positively correlated to temperature, when the temperature is 80℃, the reaction rate and DST value are the largest; while when the temperature is above 80℃ and BOZ concentration is over 160 mg/L, DST value and the reaction rate decrease gradually. Related Articles | Metrics Select Alkylation of Benzene with C16~C18 Olefins Catalyzed by [Bmim]Cl/AlCl3 Ionic Liquid DONG Bin-qi;WU Qin;HAN Ming-han;XIN Hong-liang    2007, 7 (1): 59-62.   Abstract （1794）      PDF （193KB）（735）       Knowledge map    Save The alkylation of benzene with a-C16~C18 olefins catalyzed by 1-butyl-3-methylimidazolium-aluminum chloride ([Bmim]Cl/AlCl3) ionic liquid with different aluminum chloride molar fractions was studied under different reaction conditions. At room temperature, a high conversion rate of 98% of olefins and a high selectivity of 46% of 2-alkylbenzene were obtained within 30 min when the aluminum chloride molar fraction x was 0.67 and molar ratio of AlCl3 in the catalyst to olefins was 0.04. The Lewis acidity strength of the ionic liquids with different molar fractions of aluminum chloride, which was characterized by infrared spectroscopy using acetonitrile molecule as probe, was correlated with the performance of catalyst in alkylation reaction. The ionic liquid showing a strong Lewis acidity strength had good performance in alkylation reaction. Strong polarizabilities of the ionic liquid characterized by FT-IR spectra using benzene as molecule probe could stabilize the carbenium ion intermediate. In addition, the effect of different olefins on alkylation reaction was also investigated. Related Articles | Metrics Select Chelating Properties of Ni2+ on Phe Resin SHEN Jun;WEI Rong-qing;LIU Xiao-ning;WANG Yan-qin    2007, 7 (1): 63-66.   Abstract （1659）      PDF （184KB）（662）       Knowledge map    Save A new L-phenylalanine resin (PS-Acyl-Phe) was prepared by chloroacetylated polystyrene (PS-Acyl-Cl) instead of merrifield resin (PS-CH2-Cl) and applied for chelating Ni2+. The effects of pH, chelating time and concentration of Ni2+ on the chelating reaction were investigated for the optimal chelating condition. The results show that under the optimal conditions of Ni2+ concentration 0.1 mol/L, pH 3.5~9.0, and chelating time 1 h, the chelating rate could be up to 40.8%. Related Articles | Metrics Select Microemulsion with Span/Tween as Mixed-surfactant and Synthesis of Iron Nanoparticles LIU Hai-shui;LI Tie-long;JIN Zhao-hui;GOAN Yan-zhang;ZHAGN Yun-xia    2007, 7 (1): 67-70.   Abstract （1595）      PDF （326KB）（893）       Knowledge map    Save Three kinds of microemulsion systems with different compositions formed by iso-octane/Span80-Tween60/n-butanol, edible oil/Span80-Tween60/n-butanol and edible oil/Span80-Tween60/n-butanol were studied. The system of iso-octane/Span80-Tween60/ n-butanol is the best choice for the purpose of microreactor when the hydrophile-lipophile balance value is 14, content of emulsion (mass ratio of surfactant to oilphase) is 0.5, Co/S=0.5 (Co/S is the mass ratio of co-surfactant-to-surfactant). The nanosized iron particles with average diameter of 80 nm were synthesized with the system. Related Articles | Metrics Select Synthesis of Silicalite-1 Zeolite Membrane by Nanocrystal Seed Coating Method KONG Chun-long;WANG Jin-qu;LU Jin-ming;TAO Kai    2007, 7 (1): 71-74.   Abstract （1526）      PDF （641KB）（751）       Knowledge map    Save The Silicalite-1 zeolite membrane was prepared by secondary synthesis on the porous a-Al2O3 support. The samples were characterized by XRD and SEM, and the permeant selectivity of the membrane was characterized by single-gas at room temperature. The results showed that the membrane re-grew, its thickness was about 8~10 mm and the ideal separation factors were 3.9 for H2/N2 and 19.1 for H2/C3H8 at room temperature, respectively, which are larger than the Knudsen diffusion ratios 3.74 for H2/N2 and 4.69 for H2/C3H8, the permeation rate of H2 was 1.43′10-6 mol/(m2×s×Pa). The data of gas permeation indicated that the membrane was defect-free. Related Articles | Metrics Select Rare Earth Extraction from Mixed Bastnaesite-Monazite Concentrate by Carbochlorination-Oxidation ZHANG Li-qing;ZHANG Feng-chun;YAO Shu-hua;JING Lin-lin;WANG Xiao-huan    2007, 7 (1): 75-78.   Abstract （1701）      PDF （192KB）（813）       Knowledge map    Save A stepwise carbochlorination-oxidation process was developed for the rare earth extraction from mixed bastnaesite-monazite concentrate using carbon as reductant, chlorine gas as chlorination agent, SiCl4 gas as defluorination agent, and O2+H2O mixed gas as oxidant. Under the temperatures from 500℃ to 800℃, the rare earth chlorinated conversion rate for 2 h was 56% to 88% in the absence of SiCl4, but 92% to 99% in the presence of SiCl4. The residue of carbochlorination of the mixed concentrate at 500℃ for 2 h mainly contained LnCl3 and CaCl2. When the temperature of carbochlorination was below 500℃, the portion of evaporated thorium to the thorium in the raw material was less 1.0%. The product of carbochlorination was leached with water and solidified in air. The subsequent oxidation of the solid chloride mixture in the wet air at 550℃ for 90 min may result in the separation of rare earth elements and non-rare earth elements, and the separation of Ce and non-Ce elements. Related Articles | Metrics Select Research of Formation Mechanism on Cementitious Reactivity of Water-cooled Slag LI Yu;SUN Heng-hu;ZHAO Yong-hong;WANG Nan    2007, 7 (1): 79-84.   Abstract （1536）      PDF （621KB）（603）       Knowledge map    Save Water-quenched samples were prepared by re-melting blast furnace slag and then quenching it at different temperatures. The effects of forming process on the relationship between structure and cementitious reactivity of quenched slag were studied by XRD, DTA, TEM, SEM and EDX techniques in combination with mechanical property and alkali leaching tests. The results show that phase separation phenomena of different extents exist in samples. The samples with phase separation in completely vitreous structure possess better cementitious reactivity. Such vitreous structure consists of both Ca-rich and Si-rich phases. Rapid dissolving of Ca-rich phase and slow dissolving of Si-rich phase contribute to the cementitious reactivity of quenched slag. Related Articles | Metrics Select Preparation of Potassium Titanate Whiskers and Titanium Dioxide from Titaniferous Slag Using KOH Sub-molten Salt Method TONG Qi-jie;QI Tao;LIU Yu-min;WANG Li-na;ZHANG Yi    2007, 7 (1): 85-89.   Abstract （1584）      PDF （1133KB）（688）       Knowledge map    Save KOH sub-molten salt method was studied for preparing potassium titanate whiskers and titanium dioxide by using titaniferous slag as the raw material. The effects of reaction temperature, reaction time, initial KOH concentration and mass ratio of alkali-to-slag on the morphology of the products were investigated. The results show that the reaction temperature, the reaction time and the mass ratio of alkali-to-slag have influences on the morphology of the whiskers. The whiskers obtained have 20~25 mm in length, and 15~20 in length-diameter ratio. Potassium titanate (KTi8O16.5) whiskers can be obtained by calcining the hydrolytic products of potassium titanate (K4Ti3O8), while the pH value of the solution is 10~12. And TiO2 whiskers can be obtained by calcining the hydrolytic products of potassium titanate (K4Ti3O8), while the pH value of the solution is 1~3. Related Articles | Metrics Select Preparation of Ti-pillared Montmorillonite Tailored by Surfactant YAN Shu-fang;YU Jiang;LIU Hui-zhou;SUN Ti-chang    2007, 7 (1): 90-94.   Abstract （1537）      PDF （266KB）（667）       Knowledge map    Save A new method was proposed for preparation of photocatalyst TiO2-pillared montmorillonite with application of cetyltrimethylammonium bromide (CTAB) as a structure-oriented agent. The effect of amount of CTAB on the interlayer distance of Ti-pillared montmorillonite was investigated. And the differences of nano-TiO2 particle size and morphology before and after calcination at 500℃ were highlighted. The experimental results indicated that the "growth" of the hydrated Ti-polycations within clay interlayers could be regulated and controlled by the surfactant CTAB as the structure-oriented agent. FT-Raman spectroscopy and XRD were used to characterize the modified montmorillonite materials. The possible micro-mechanism of Ti-pillared montmorrilonite tailored by the surfactant CTAB was proposed. The modified montmorillonite material is expected to be an alternative to the preparation of water treatment materials with high adsorption capacity and photocatalytic activity. Related Articles | Metrics Select Preparation of Ultrafine Chromia Particles by Hydrothermal Reduction and Size Control ZHANG Peng;CAO Hong-bin;XU Hong-bin;ZHANG Yi    2007, 7 (1): 95-99.   Abstract （1648）      PDF （392KB）（668）       Knowledge map    Save Preparation of ultrafine chromia particles by hydrothermal reduction and size control was investigated. With CO2 as acidifying agent, potassium chromate was directly reduced to chromic oxide hydrate under hydrothermal conditions using formaldehyde as reducing agent. In addition some surfactants, such as TPP, PAM, PEG-600, PVP etc., were added to the system to control particle size for the first time. Then chromic oxide hydrate was converted into ultrafine spheral Cr2O3 particles by calcination at 800℃. The effects of the mole ratio of formaldehyde to chromate (Rm), the initial partial pressure of CO2 (pCO2), the isothermal temperature (Tiso) and time (tiso) on the conversion of Cr(VI) were also studied in detail and the optimum technological conditions were suggested. The conversion rate of Cr(VI) was 99.9% under the optimum conditions and the average particle size of spheral Cr2O3 was about 100 nm. The experimental results showed that surfactants were useful for controlling particle size and morphology. The new process showed a promising application prospect as the technique, economy and simpleness were concerned. Related Articles | Metrics Select Combined Technology of Catalytic Esterification and Adsorption Dehydration of Succinic Acid DING Bin;CHEN Lian-fa;HAO Feng-ling;GUAN Chang;MIAO Nai-fen    2007, 7 (1): 100-104.   Abstract （2503）      PDF （223KB）（704）       Knowledge map    Save Synthesis of dimethyl succinate from succinic acid and methanol on cation exchange resin NKC-9 was studied under adsorption dehydration with 3A zeolite adsorbent. The effects of reaction conditions, such as molar ratio of methanol to succinic acid, catalyst content and reaction time, were investigated. The optimum reaction conditions were obtained, which were nmethanol:nsuccinic acid= 3.0:1, catalyst content 3.5% (relative to total mass of succinic acid and methanol), reaction temperature≤120℃, reaction time 4.0 h. Conversion rate of succinic acid by the process could reach 98.86%, and activity of catalyst was still kept at 98.09% after 6 times used. Analysis of the synthesized product by means of FT-IR and GC-MS showed that no by-product was observed in this process. Selectivity of catalyst was excellent. Related Articles | Metrics Select Electrostatic Classification of Fine Powders XU Zheng;XIE Tao;LU Shou-ci;SHEN Zhi-gang    2007, 7 (1): 105-109.   Abstract （1513）      PDF （267KB）（744）       Knowledge map    Save For obtaining precise powder classification to adapt the strict need for special size powder, a new method and apparatus which charges the particles with electrostatic charges and then put them into an electric field to make them classified in the particle sizes was presented in this work. The charging and classifying test was done on -75 mm copper powder and different sizes of SiC powder. The results show that the maximum ratio of charge to mass is -14.8 nC/g for copper powder, -90.6, -43.2, -50.7 nC/g for W10, W20 and W40 SiC powder samples respectively. The micrographs of the classified copper powder show that the high charge voltage leads to better classification result. The classification results of SiC powder are evaluated by cumulating mass fraction. The cumulating mass fraction of powder above 25 mm promoted from 3.77% to 2.39% for sample II and from 1.80% to 0.93% for sample III. The electrostatic classification of powder is a future potential method. Related Articles | Metrics Select Precipitation Behavior of Perovskite Phase in Oxidized Titanium-bearing Slag WANG Ming-yu;LOU Tai-ping;SUI Zhi-tong    2007, 7 (1): 110-112.   Abstract （1654）      PDF （201KB）（657）       Knowledge map    Save In order to promote the enrichment of titanium component in perovskite phase, based on the technology of selective precipitation, the slag is supposed to be oxidized. In this work, the non-isothermal precipitating behavior of perovskite phase in oxidized titanium bearing slag was studied by quenching method, and the precipitating process kinetics of perovskite phase was analyzed. The results show that the precipitating of perovskite phase is related to the cooling rate, i.e. the lower the cooling rate, the higher the volume fraction of perovskite phase. The precipitation kinetics of perovskite phase can be approximately described by the JMAK equation. Related Articles | Metrics Select Carbazole Degradation by Klebsiella sp. LSSE-H2 HUANG Jie-xun;XIONG Xiao-chao;LI Wang-liang;LI Xin;XING Jian-min;LIU Hui-zhou    2007, 7 (1): 113-118.   Abstract （1713）      PDF （255KB）（698）       Knowledge map    Save A novel bacterial strain LSSE-H2 isolated from dye-contaminated soil could use carbazole as the sole source of carbon, nitrogen and energy. Based on the phylogenetic analysis of the 16S rRNA gene, this strain was identified as Klebsiella sp. At 30℃, strain LSSE-H2 could almost completely degrade 12 mmol/L carbazole as the sole source of carbon, nitrogen and energy in carbon- and nitrogen-free media (CNFM) after 56 h of cultivation. High carbazole degradation activity was also observed in 16 mmol/L carbazole. Analysis of the carbazole degradation in different culture media indicated that LSSE-H2 possessed unique regulation mode of the expression of carbazole-degrading capacity. Using two sharing primers for Sphingomonas sp. KA1 and Sphingomonas sp. GTIN11, the carbazole degradation gene cluster containing five car genes was amplified by polymerase chain reaction (PCR), and these genes were 100% homologous to KA1 and GTIN11 genes except several different points in the non-coding region of the gene cluster. It may be deduced that the car gene clusters in LSSE-H2, KA1 and GTIN11 have the same origin, and could laterally transfer between different bacteria. Related Articles | Metrics Select Behavior of Hyaluronic Acid in Electro-Membrane Separation ZHANG Jian-dong;ZHOU Hai-dong;NI Jin-ren    2007, 7 (1): 119-123.   Abstract （1633）      PDF （253KB）（666）       Knowledge map    Save An electro-membrane separation technique was introduced to extract hyaluronic acid from fermentation broth. The present studies were focused on the behavior of hyaluronic acid under electrical field and the effects of hyaluronic acid concentration, pH, ion strength and electric current intensity on the extraction. The results show that the extraction rate of hyaluronic acid is proportional to the concentration and the electric current. The electrophoresis mobility of hyaluronic acid is kept constant within pH 7~9, and the extraction of hyaluronic acid is independent of pore size. The separation experiment with fermentation broth shows that hyaluronic acid can be fully separated from proteins in broth. Related Articles | Metrics Select Fermentation of Temperature-induced Recombinant Escherichia coli for Glutathione Synthesis and Its Induction Expression LIAO Xian-yan;ZHU Zhi;CHEN Jian;DU Guo-cheng    2007, 7 (1): 124-128.   Abstract （1660）      PDF （233KB）（662）       Knowledge map    Save The fed-batch fermentation of temperature induced recombinant E. coli for glutathione production was investigated. It is demonstrated that acetic acid could be controlled at low concentration by using dissolved oxygen responses to glucose feeding pulse. Based on the results, the fed-batch fermentation of the addition of yeast extracts and tryptone together with glucose in the expression phase of glutathione synthetic enzymes system was further studied. Applying the feedback control of dissolved oxygen responses to pulse in glucose feeding, acetic acid accumulation was successfully prevented. And the addition of yeast extracts and tryptone was beneficial to the expression of glutathione synthetic enzymes system. The concentration of glutathione reached 2.46 g/L in the enzymatic synthesis by using recombinant E. coli induced for 4 h at 42 ℃. Related Articles | Metrics Select Rapid and High Frequent Induction of Saffron Corms CHEN Wen-hao;OU Yuan;ZHAO Bing;WANG Xiao-dong;WANG Yu-chun    2007, 7 (1): 129-132.   Abstract （1542）      PDF （216KB）（593）       Knowledge map    Save The effects of exogenous plant hormones and activated carbon (AC) on the development of saffron corms in vitro were studied. Both hormone concentration and AC level influenced corm induction. When 1/2 Murashige and Skoog medium was supplemented with low concentration of hormones, corms were induced quickly while big corms formed slowly at high concentration of hormones. The addition of AC decreased the concentration of free hormones and the time of corm development significantly, while the slow release of hormones raised corm size. In the medium with optimal 0.5 g/L AC, high induction rate (85.7%) and big corms (0.53 g average weight) were obtained in 5 weeks when 5 mg/L naphthalene acetic acid and 5 mg/L 6-benzylaminopuine were added to the medium. Related Articles | Metrics Select Induction and Regulation of Crocus sativus L. Embryogenic Callus CHEN Shu-an;WANG Xiao-dong;ZHAO Bing;WANG Yu-chun    2007, 7 (1): 133-136.   Abstract （1588）      PDF （199KB）（688）       Knowledge map    Save The induction and regulation of embryogenic callus were investigated to promote the growth and shoot induction rate for micropropagation of Crocus sativus L. The embryogenic callus line was obtained easily from one corm callus line (corm 1). After 25 d, the maximum proliferation rate of callus reached 8.9 g/g under the optimized condition for cell growth when the callus was cultured on B5 medium supplemented with 400 mg/L CH, 0.25 mg/L NAA and 3.0 mg/L 6-BA at 22℃ in darkness. After 45 d, the maximum shoot induction rate of callus reached 45% under the optimized condition for shoot induction when the callus was cultured on 1/2 B5 medium supplemented with 400 mg/L CH, 0.25 mg/L NAA and 3.0 mg/L 6-BA at 22℃ under 16 h light with the intensity of 31.74 mmol/(m2×s) per day, while the highest shoot induction rate of Crocus sativus L. callus was reported only about 20% abroad. Related Articles | Metrics Select Enzymatic Transesterification of Yeast Oil for Biodiesel Fuel Production LI Wei;DU Wei;LI Yong-hong;LIU De-hua;ZHAO Zong-bao    2007, 7 (1): 137-140.   Abstract （2735）      PDF （200KB）（818）       Knowledge map    Save Microbial oil obtained from a yeast strain (Rhodosporidum toruloides Y4#) by acid-heating extraction was characterized, including fatty acid analysis by gas chromatography. The oil was further explored for biodiesel production by lipase-catalyzed methanolysis. Two processes were studied, namely, three-step methanol loading in solvent-free system and all-in-one methanol loading in tert-butanol system. It was demonstrated that the microbial oil could be converted to biodiesel effectively. The biodiesel yield of about 90% could be obtained under the optimized conditions, which was slightly lower than that of refined soybean oil as the raw material. Related Articles | Metrics Select Investigation on Purification and Properties of Extracellular Lipase from Candida sp. QIN Shao-wei;YU Ming-rui;TAN Tian-wei    2007, 7 (1): 141-144.   Abstract （1695）      PDF （213KB）（670）       Knowledge map    Save The extracellular lipase from Candida sp. 99-125 was purified by ion exchange chromatography and hydrophobic interaction chromatography. The results showed that the specific activity of the purified enzyme was raised by 10.0 times and the activity recovery was 35.5%. The molecular weight of the purified lipase was determined to be about 38 kDa by SDS-PAGE in Coomassie brilliant blue staining. The optimum pH and temperature of the purified enzyme were 8.5 and 40℃ respectively. The purified lipase remained 95% activity after incubated for 2 d at room temperature (20℃). Fe2+, Cu2+ and SDS had an inhibitory effect on lipase activity, whereas Ca2+ salts and Tween80 increased it. Related Articles | Metrics Select Investigation of Metabolic Routes to Poly(glutamic acid) by 13C-labeled Glucose as Medium Carbon Source SHI Ning-ning;XU Hong;YAO Jun;WANG Jun    2007, 7 (1): 145-148.   Abstract （1873）      PDF （255KB）（1293）       Knowledge map    Save Bacillus subtilis NX-2 produce was used to g-poly(glutamic acid) (g-PGA) with glucose and glutamic acid as medium carbon sources. To clarify the role of these carbon sources in g-PGA synthesis, metabolic routes to g-poly glutamic acid were investigated using 13C-labeled glucose as medium carbon source by detecting 13C-NMR peak intensity. When the medium glucose concentration was 4%, the repeat units of g-PGA formed from glucose were approximately 9%. While the medium glucose concentration was 3%, the repeat units formed from glucose fell to 6%. Glucose was mainly used to form biomass and provide adenosine tri-phosphate (ATP) for g-PGA synthesis, while glutamic acid was the main source of g-PGA repeat units. Related Articles | Metrics Select Production of Lipase by Penicillium camembertii Thom in Fermentation with Defatted Soybean Meal ZHANG Da-hao;LI Dan;WANG Bing-wu;TAN Tian-wei    2007, 7 (1): 149-151.   Abstract （1508）      PDF （169KB）（669）       Knowledge map    Save Fed-batch fermentation with Penicillium camembertii Thom by feeding defatted soybean meal to produce lipase was studied. The effect of several feeding strategies including batch feeding, both high and low concentration feeding on lipase production was investigated. The highest lipase activity of 392 IU/mL was achieved by feeding high concentration defatted soybean meal in a 5 L fermentor after 99.8 h of the cultivation, no other carbon source was added in the cultivation. The cost of the lipase production was remarkably reduced using this feeding strategy due to the absence of jojoba oil in the culture medium. Related Articles | Metrics Select Interfacial Properties of Ethyl Cellulose/Cellulose Acetate Blends by HPLC GAO Su-lian;ZHOU Ning-guo;ZHANG Xiu-zhen;ZHANG Wei    2007, 7 (1): 152-154.   Abstract （1621）      PDF （86KB）（613）       Knowledge map    Save The high performance liquid chromatography method (HPLC) with ethyl cellulose/cellulose acetate (EC/CA) blends and EC as column packing material, and small molecular weight compound as probe molecules was employed to measure the retention volume (VR) and equilibrium distribution coefficient (K) of both inorganic and organic solutes. The interfacial separation properties of EC/CA blends were characterized by the HPLC data. The effects of the blends on the interfacial adsorption properties, hydrophilicity, affinity, polar and non-polar parameters of EC membrane materials were studied subsequently. The research results indicate that the interfacial adsorption properties and hydrophilicity of EC have been improved by solution blending with CA. The alloys are superior to EC in the separation efficiency for non-dissociable polar organic solute. The EC/CA alloy (80:20, w) is suitable for desalting and desaccharifying. Related Articles | Metrics Select Synthesis and Catalytic Properties of NiCu Composite Metal Nanopowder LIU Lei-li;LI Feng-sheng;YANG Yi;BAI Hua-ping    2007, 7 (1): 155-159.   Abstract （1437）      PDF （239KB）（550）       Knowledge map    Save NiCu composite metal nanopowder was prepared by chemical reduction and its structure was determined. The thermal decomposition behaviour of ammonium perchlorate (AP) was investigated in the presence of NiCu composite metal nanopowder by DTA. The results show that nanometer Ni60Cu40 composite powder decreased the lower and higher thermal decomposition temperatures of AP by 26.8 and 140.4℃ respectively, and the DTA heat release of AP in the presence of NiCu nanopowders increased to 1.29 kJ/g, showing good catalytic effects on the thermal decomposition of AP. The composition of NiCu composite nanopowder influenced its catalytic effect and Ni60Cu40 had the best catalytic effect. With the increase in content, NiCu nanopowder enhanced its catalytic effect on the decomposition of AP. The mechanism of catalyzing the thermal decomposition of AP was proposed as follows: (1) metal oxide acts as the intermedium in the process of election transfer, (2) NiCu nanopowder reacts with the decomposed products of AP, and (3) NiCu nanopowder has special surface effect. Related Articles | Metrics Select Template-based Synthesis and Micro-structure Characterization of TiO2 Nano-array ZHU Bin;DAI Xia-ming;LI Qing-feng;DENG Chang-sheng    2007, 7 (1): 160-163.   Abstract （1402）      PDF （734KB）（705）       Knowledge map    Save Titanium dioxide nanotube and nanorod arrays were successfully prepared by the combination of sol-gel and AAO (anodic aluminum oxide) membrane fabrication. The precursor of titanium dioxide sol-gel is tetra-isopropyl titanite, and the dipping processing is based on direct dipping or under negative pressure. The products were characterized with FE-SEM, HR-TEM and XRD after heat treatment of samples at 450℃ and removing AAO membranes with NaOH. The results show that the template method is effective in fabricating nanotube arrays, and the products were polycrystalline. The outer diameter of nanotubes is determined by the pore size of template. The pore size and thickness of the membranes used in the experiments were 200 nm and 60 mm respectively. Related Articles | Metrics Select Preparation and Properties of Ordered Mesoporous Silica Film LIN Xue-jing;SHEN Jun;XIE Zhi-yong;YAO Lan-fang;WU Xiao-xian;LUO Ai-yun    2007, 7 (1): 164-167.   Abstract （2788）      PDF （350KB）（751）       Knowledge map    Save Mesoporous silica film was successfully prepared through molecular self-assembly. A precursor sol containing tetraethoxysilane (TEOS), the surfactant template cetyltrimethylammonium bromide (CTAB) and acid catalyst was prepared by sol-gel process. The hexagonal ordered structure of the calcined mesoporous silica film was confirmed by TEM. The refractive index of the directly calcined film is 1.18, the film thickness is about 180 nm, which was performed by spectroscopic ellipsometry measurements. The dielectric constant k of the directly calcined film was 2.14. The hexamethydisilazane (HMDS) vapor treatment is considered to be effective possibly for generating hydrophobic mesoporous silica thin film, and the resulting film will be more useful as low dielectric constant intermetal material in advanced semiconductor devices. Related Articles | Metrics Select A New Method for Preparing Nanocrystalline Ternary Telluride and Its Characterization LIU Xing-zhi;ZHAO Chang-ming;CHEN Lin;WANG Yan;XIONG Ying    2007, 7 (1): 168-171.   Abstract （2176）      PDF （199KB）（676）       Knowledge map    Save The nanocrystalline Ag8SnTe6 was prepared by microwave solvothermal technique with AgNO3, SnCl2·H2O and Te powder as materials. Several analytical techniques, such as XRD, TEM and XPS, were used to characterize its composition. The effects of reaction time and organic solvent tamping degree on product productivity and the mechanism of the formation of nanoctystals were discussed. The UV-Vis results showed that this compound was preferable semiconductor with a band gap of 2.58 eV. Related Articles | Metrics Select Preparation of Highly Efficient Green ZnO Phosphor by Calcining ZnS and NaCl Mixture in Air Atmosphere LI Ying-yi;SONG Zhi-bin;LUO Jun-ming;WU Yan-li;FENG Xiao-ping;LI Yong-xiu    2007, 7 (1): 172-175.   Abstract （1652）      PDF （204KB）（723）       Knowledge map    Save ZnO phosphors with highly efficient green luminescent emission have been prepared by calcining ZnS in air atmosphere at different temperatures with NaCl as flux. The photoluminescence spectra and the contents of S and Cl of ZnO phosphor were determined. The results showed that the phosphors were composed of ZnO with hexagonal wurtzite structure, however, few of cubic ZnS still remained. Under excitation of 350 nm radiation, the phosphors emit strong green light at around 510 nm with no band to band exciton emission around at 380 nm. According to accepter-donor transition mechanism, this green emission band can be ascribed to a transition of photogenerated electrons from the localized defect centers (donor) to deeply trapped holes (acceptor) in the bandgap. The highly enhacement of NaCl for the luminescent emission of ZnO is attributed to the co-doping of S and Cl, which results in the formation of defects both VO+ and Zn(1-z)+. The phosphor prepared at 700℃ showed the highest luminescent intensity under 380 nm irradiation, and could be used in white light-emitting diodes (LEDs). Related Articles | Metrics Select The State-of-the-art and Future Perspectives of World Petroleum Refining Technology LIU Hai-yan;YU Jian-ning;BAO Xiao-jun    2007, 7 (1): 176-185.   Abstract （3191）      PDF （280KB）（859）       Knowledge map    Save Entering into the 21st century, world petroleum refining technology is experiencing its great innovation driven by the increasing supply of heavy oils with decreasing quality and the fast increases in the demand for clean and ultra-clean vehicle fuels and petrochemical raw materials. In this review, the current situation of the world petroleum refining industry and technology is analysed and our outlook into the future technological innovations is presented. It is concluded that the main technological progress will be directed to heavy oil upgrading, cleaner transportation fuel production and the integration of refining and petrochemical businesses. For heavy oil upgrading, hydrocracking and hydrotreating technology will be the main directions, new residue FCC technology and new delayed coking should be developed further. For cleaner transportation fuel production, the main task is the desulfurization of gasoline and diesel. With the advents of various techniques, such as adsorption and biodesulfurization, the future development will be still centralized on hydro-desulfurization techniques. In the integration of refining and petrochemical businesses, new technologies based on traditional FCC process will be of increased interests to refiners because of their potential to meet the increasing demand for light olefins. Meanwhile, hydrocracking, due to its flexibility, will take the central position in the integration of refining and petrochemical businesses in 21st century. Related Articles | Metrics Select Applications of Microwave in Metallurgical Processes LI Fan;ZHANG Mei;WANG Xi-dong    2007, 7 (1): 186-193.   Abstract （1655）      PDF （353KB）（796）       Knowledge map    Save Microwave processes have been rapidly developed for the last two decades in many areas, but the application of microwave in metallurgical processes is just at the initial stage. This paper presents a review on the research and development results of microwave technology applied in mineral treatment, material preparing process and metal recovery operations such as heating, comminution, carbothermic reduction of oxide mineral, leaching and some of metallurgical waste treatments. Despite in this area a significant number of research studies have been carried out and many results obtained, which exhibits a lot of advantages in metallurgical processes. The mechanism of interaction of microwave with minerals and materials and understanding of some phenomena occurring in a microwave-assisted process are still not explained clearly, so that more investigation will be needed in the future. The conversion efficiency of microwave energy, high power microwave generator and designing efficient reactor are key problems to be overcome for improving industrial applications. Related Articles | Metrics page Page 1 of 6 Total 235 records First page Prev page Next page Last page