Table of Content

20 October 2009, Volume 9 Issue 5

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流动与传递

CFD Simulation of Gas-Liquid Flow in Bubble Column with Two-bubble Phase Population Balance Model

LI Guang YANG Xiao-gang DAI Gan-ce

. 2009, 9(5):  833-840. 

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A two-bubble phase population balance model (TBPBM) was proposed by treating gas phase (bubbles) as two groups consisting of small and large bubbles, i.e. accounting for small and large bubble phases in terms of different laws of bubble dynamics based on the sizes of bubbles, in which the population balance model was applied and solved respectively for each bubble group to predict the bubble Sauter diameters. The use of two-fluid model coupled with the TBPBM has been tested to simulate hydrodynamics in a bubble column of 440 mm in diameter at the superficial gas velocity of 0.1 m/s. Bubble classes holdup-based probability distribution, radial profiles of time-averaged axial liquid velocity and gas holdup and bubble size distribution for each phase were obtained. The simulation has demonstrated that the predicted profiles of mean gas holdup and liquid velocity are in good agreement with the experimental data and the existing results reported in the literature. The simulation also indicates that the TBPBM model is superior to the SBPBM and mean bubble size models in bubble column hydrodynamics simulation. The error of the predicted overall gas holdup caused by using TBPBM model is 5.7%, while the errors by using SBPBM model and mean bubble size model are 27.2% and 17.3%, respectively.

Numerical Simulation of Thermal Convection in Triangular Enclosure Using Lattice Boltzmann Method

YONG Yu-mei YANG Chao MAO Zai-sha

. 2009, 9(5):  841-847. 

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The natural convection in triangular enclosures occurs widely in the fields of electronic device cooling, solar energy collector and so on. The two-dimensional impressible lattice Boltzmann model is built in this work for its simulation. On the basis of D2G9 model, coupling with the two-dimensional thermal lattice Boltzmann model TD2Q5 and non-equilibrium extrapolation boundary scheme, the temperature field in Couette flow is simulated. The predicted results of Couette flow agree well with the analytical solution when the Eckert number varies from 5 to 100, which shows that the present thermal model TD2Q5 is accurate and numerically stable. The velocity and temperature fields of natural convection in a triangular enclosure are solved at different Rayleigh number values. The predicted results coincide very well with that reported in the literature, indicating the present numerical models may be extended for thermal flows in triangular enclosures with higher Rayleigh number.

Influence of Deposit Loading on Detachment of Fine Particles Formed Cakes

XU Hai-wei LI Shui-qing SONG Qiang YAO Qiang

. 2009, 9(5):  848-853. 

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Fine particles with mean size of 3.31 mm were used to form cakes on PPS filter or PET membrane filter with different deposit loadings. With a slowly increased reverse flow, the cakes were slowly blown out and the cake cleaning stress curve was measured. Meanwhile a low pressure pulse cleaning method was used to simulate the real pulse cleaning in practice. The results by both methods were compared and exhibited the agreement in predicting cleaning stress. The cake detachment stress decreased as the cake loading increases for both filters. For instance, the detachment stress of PET membrane filter decreased from 350 to 100 N/m2 as the cake loading increased from 200 to 401 g/m2, which was 90 N/m2 lower than that of the PPS filter. The low pressure pulse cleaning efficiency of PPS filter cakes showed a linear relationship to the cake loading, while the efficiency of PET membrane filter increased much quickly when the cake loading was lower than 200 g/m2. The cake patches obviously became larger as the cake loading increases for both filters.

Gas-Liquid Dispersion by Hollow-blade Disk Turbines with Different Blade Shapes

MA Zhi-chao BAO Yu-yun GAO Na GAO Zheng-ming

. 2009, 9(5):  854-859. 

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The influences of different blade profiles on critical impeller speed for gas dispersion, gassed power consumption and gas holdup were studied in a 0.48 m i.d. stirred tank with dished base agitated by four different hollow-blade disk turbines respectively, which were identified as parabolic blades disk turbine (PDT) and half elliptical blades disk turbine (HEDT). The results show that the flooding transitions measured from loading to flooding show a hysteresis compared with that measured from flooding to loading with increasing and falling gas rates. Comparing the gassed power consumption and gas holdup between PDT and HEDT impellers, under the same flow number, PDT impeller has higher relative power demand (Pg/P0, the ratio of gassed power to ungassed power), usually higher than 0.75, and has less influence to the gas rates, PDT impeller has about 5% higher gas holdup than HEDT impeller over a wide range of gas rates and better loading capacity. Moreover, the power consumption of PDT impeller is lower to obtain the gas-liquid dispersion at the same gas flowing rate, therefore it is recommended to the industrial application of the gas-liquid stirred reactors.

Performance Indices of Particulate Matter Resuspension and Measurement Systems

HUANG Yu-hu JIN Da-jian MAO Hua-yun ZHU Ping; LI Gang TIAN Gang;

. 2009, 9(5):  860-864. 

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The performance indices of resuspension and measurement systems were systematically brought forward. The indices should include five aspects at least, the stability of particles concentration, equilibrium time of concentration adjusting and continuous running time, adjustable range of concentration, sampling uniformity of particles, and consistency of particles size distribution. A particulate matter resuspension and measurement system was designed according to the pneumatic redispersion of dry dust and mechanics theory of aerosol which is evaluated in terms of the indices. The evaluation result shows that the concentration of particles can be adjusted in the range of 0.1~12000 mg/m3, the equilibrium time of concentration adjusting is less than 1 min, the continuous running time can reach 1~7 d at least, the concentration is stable, and the average of concentration RSDs is less than 10% under various running states of system, the samples, from different sampling points within the uniform mixing chamber, get good uniformity, RSD≤1.5%, the particles size distribution in uniform mixing chamber can keep consistency with testing dust in the range of 0~40 mm for aerodynamic diameter.

反应与分离

Kinetics and Thermodynamics of the Adsorption of Copper(II) onto Chelating Resin

LIU Bu-yun YAO Zhong ZHOU Zhi XU Hong WEI Ping

. 2009, 9(5):  865-870. 

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The kinetics and thermodynamics of copper(II) adsorption onto D401 chelating resin were studied as for removal of copper(II) from enzymatic synthesis of L-theanine using glutamine-copper(II) as donor substrate. The structures of copper loaded resin were confirmed by infrared spectroscopy. Adsorption capacity of copper(II) increased with increasing initial metal ion concentration and temperature. And its highest value was 1.887 mmol/g at pH 5.6. Experimental data fitted well to the Langmuir model at all temperatures studied. The thermodynamic equilibrium functions were also determined. DG<0, DH=21.5 kJ/mol, DS>0, so the adsorption was spontaneous, endothermic and entropy increasing. The kinetic experimental data were correlated with pseudo-second-order kinetic model. The adsorption rate was controlled by film diffusion and particle diffusion simultaneously throughout the entire adsorption period. The resin could be applied to the removal of copper(II) from theanine-copper complexes by enzymatic synthesis under wide pH range, with a good selectivity with copper(II).

Removal of Vanadium(V) and Chromium(VI) from High Concentration Sodium Phosphate Solution with Ion-exchange Resins

SHEN Ni LIN Xiao CAO Hong-bin GUO Fen WANG Shao-na

. 2009, 9(5):  871-876. 

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Removal of vanadium(V) and chromium(VI) from high concentration sodium phosphate solution was studied by ion-exchange technology, focusing on the influential factors of resin characters, adsorption temperature, pH value and ratio of solid to liquid. The results showed that D301R was selected as the optimal resin from five macroporous styrene resins. With D301R resin at the pH of 6.5, room temperature, and ratio of resin to solution of 1:10, the removing effects were favorable. Ten cycles of dynamic experiments showed that removal rates of vanadium(V) and chromium(VI) were 90% and 80% respectively, and the repeatability of resin was stable. The adsorption of vanadium(V) on D301R resin was controlled by replacing process of phosphorus, and the mass transfer rate of vanadium(V) was much lower than that of chromium(VI).

Reaction Behavior of Al2O3 and Fe2O3 in Na2O-Al2O3-Fe2O3 Systems during Sintering

LI Xiao-bin ZHANG Zhi-qiang LIU Wei LIU Gui-hua PENG Zhi-hong ZHOU Qiu-sheng

. 2009, 9(5):  877-881. 

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The reaction behavior of Al2O3 and Fe2O3 in Na2O-Al2O3-Fe2O3 system was investigated in detail with Al2O3, Fe2O3 and Na2CO3 as raw materials. Both Na2O×Al2O3 and Na2O×Fe2O3 formation reactions are in accordance with the Zhuralev-Lesokin- Tempelman diffusion-controlled model in kinetics based on the relationship between Al2O3/Na2O extraction rate and sintering temperature or time, and the apparent activation energy is 186.59 and 80.92 kJ/mol, respectively, and the formation of Na2O×Fe2O3 is prior to that of Na2O×Al2O3. The results also indicate that Al2O3 reacts easily with Na2O×Fe2O3 in sintering process, and Na2O×Al2O3 and Fe2O3 occur in clinker. For example, Al2O3 extraction rate of the clinker reaches to 98.51%. Fe2O3 has double effects on the formation of Na2O×Al2O3. On the one hand, it can accelerate the formation of Na2O×Al2O3 at 1273 K. But on the other hand, at the temperature higher than 1323 K, Fe2O3 can accelerate the decomposition of Na2O×Al2O3 due to the decrease of Al2O3 extraction rate in clinker leaching operation and existence of b-Al2O3 in residue, and temperature increasing or time prolongation favors the reaction between Fe2O3 and Na2O×Al2O3.

Hydrodesulfurization of Dibenzothiophen with MoO3/TiO2 Catalyst

LIU Jin-long ZHU Yin-hua YANG Zhu-hong WANG Hai-tang LU Xiao-hua FENG Xin WANG Huai-yuan

. 2009, 9(5):  882-886. 

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Mesoporous titania whiskers were used as MoO3 hydrodesulfurization catalyst support. The novel support was impregnated with ammonium heptamolybdate [(NH4)6Mo7O24×4H2O] solution at different concentrations, and MoO3/TiO2 catalyst with different MoO3 loadings was obtained. The catalyst was characterized by XRD, N2 adsorption-desorption and SEM, the one with higher dispersion of MoO3 was chosen for dibenzothiophene hydrodesulfurization. And the influences of reaction conditions and stability of MoO3/TiO2 catalyst on dibenzothiophene hydrodesulfurization of the chosen catalyst were tested in a fixed-bed reactor. Dibenzothiophene conversion rate could approach 100% under reaction temperature 280~300℃, hydrogen pressure 2.0 MPa, hydrogen/oil ratio 600 and LHSV 4 h-1. Furthermore, there was no obvious evidence of deactivation of the catalyst after running for a long time of over 1000 h.

Vacuum Distillation for Separation of Pb-Pt Alloy

YANG Chun-yu QIU Ke-qiang LIN De-qiang

. 2009, 9(5):  887-891. 

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The vacuum separation of Pb-Pt alloy was studied. Theoretical analyses show that Pb-Pt alloy could be separated by vacuum distillation. The effects of distillation temperature, distillation time and pressure on the vacuum separation were studied. The results show that the removal rate of Pb was more than 99.88% and Pt content in residues was higher than 99% when the Pb-Pt alloy containing 2.5%~15%(w) Pt was distilled for 3 h at 1250 K and 30 Pa. This method has advantages such as short process flow chart, high efficiency and no pollution to the environment.

Evaporation Characteristics of Heavy Metals in Hospital Waste Incineration Fly Ash

LIU han-qiao WEI Guo-xia ZHANG Suo-guang CAI Jiu-ju

. 2009, 9(5):  892-896. 

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The evaporation characteristics of heavy metals in hospital waste incineration fly ash were studied on a laboratory scale to obtain the effective separation parameters of heavy metals. The results show that their evaporation rates in 20 and 60 min of residence time have no obvious distinction, they depend on temperature. The abundant NaCl in the bag fly ash induces the formation of volatile chloride salts of heavy metals and enhances their evaporation. Evaporation rates of Pb and Cd in the bag fly ash are over 90% at 1000℃. Atmosphere has the significant effect on evaporation of Zn. The evaporation rate of Zn in the bag fly ash is only 67% at 1000℃ and air atmosphere, but it reaches 92% in N2 atmosphere. So, the lowest temperature of heat treatment should be controlled at about 1000℃ in view of effective separation of volatile heavy metals, such as Pb, Cd and Zn, and drastical decomposition of dioxins and furan.

过程与工艺

Combustion Characteristics of Char from Coal Topping Process

TONG Xiao-bo SHEN Chun-mei WU Shao-hua LIN Wei-gang SONG Wen-li

. 2009, 9(5):  897-903. 

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Different chars have been prepared from Datong coal with the spouted bed reactor at four pyrolysis temperatures, 550, 650, 750 and 850℃. The influence of pyrolysis temperature on the combustion characteristics of different chars is studied using a thermo-gravimetric device. A new dimensionless combustion index Z has been proposed to describe the combustion behavior of coal and char. The higher the Z value, the better the combustion behavior. Under the condition of 2℃/min heating rate for example, the Z value of Datong raw coal is 0.41, that of Yangquan anthracite 0.12, and Z values of chars at four pyrolysis temperatures, 550, 650, 750 and 850℃, respectively are 0.39, 0.35, 0.31, 0.21. The combustion reactivity of different chars is lower than that of Datong raw coal, but higher than that of Yangquan anthracite. For different chars, with the increasing of pyrolysis temperature the Z decreases, the combustion behavior becomes worse, which agrees with the variation of ignition temperature and apparent combustion activation energy.

Synthesis of Ethylene Glycol via Hydrolysis of Ethylene Carbonate Catalyzed by Immobilized Ionic liquid

WANG Yao-hong CHENG Wei-guo SUN Jian ZHANG Xiang-ping ZHANG Suo-jiang

. 2009, 9(5):  904-909. 

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The SiO2 immobilized ionic liquid catalyst S-[bpim]Br was prepared through sol-gel method. By treatment of S-[bpim]Br with potassium hydrogen carbonate, S-[bpim][HCO3] was obtained. Then, the catalytic activity of SiO2 immobilized ionic liquid in the synthesis of ethylene glycol (EG) via hydrolysis of ethylene carbonate (EC) was studied. The results showed that the immobilized basic ionic liquid S-[bpim][HCO3] exhibited good performance on the hydrolysis of ethylene carbonate and could be separated easily from the reaction system. Moreover, the effects of temperature, molar ratio of EC to H2O, reaction pressure, reaction time, and content of catalyst were also investigated in detail. The optimal reaction conditions were determined as follows: reaction temperature 140℃, reaction pressure 0.4 MPa, molar ratio of water to ethylene carbonate 2:1 and reaction time 3 h. Under above conditions, 99.7% EC conversion rate and 100% EG selectivity were obtained. Additionally, the catalyst could be reused at least 5 times with slight loss of its activity.

Optimization of Technological Conditions in Reduction of Lithium by Ferro-silicon Alloy

DI Yue-zhong DONG Wei-wei PENG Jian-ping WANG Yao-wu FENG Nai-xiang

. 2009, 9(5):  910-915. 

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Vacuum reduction with ferro-silicon alloy as reductant was used to produce lithium. The single factor and orthogonal experiments were adopted to study the effects of reduction temperature, reduction time, briquetting pressure, vacuum degree, particle size and excess coefficient of reductant on lithium reduction rate. The results indicated that the order of influential factors on the lithium reduction rate within the experimental range was obtain as follows: reduction temperature>reduction time>excess coefficient of reductant>briquetting pressure>particle size. The optimal technological parameters of lithium reduced by ferro-silicon alloy were determined as follow: reduction temperature 1293 K, reduction time 180 min, briquetting pressure 30 MPa, particle size 80 mm, and excess coefficient of reductant 50%. Under such conditions, the reduction rate was obtained as 97.85%, the purity was 99.24%.

Interactive Oxidation of Photocatalysis and Electrocatalysis for Degradation of Phenol in a Photoreactor

Fan Cai-mei WANG Yan LIANG Zhen-hai WANG Yun-fang HAO Xiao-gang; SUN Yan-ping

. 2009, 9(5):  916-921. 

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TiO2/C particles as photocatalyst were prepared by dipping TiO2 suspension solution with activated carbon and were applied in the photocatalytic-electrocatalytic degradation of phenol, the Ti/SnO2+Sb2O3/PbO2 electrode and oxygen diffusion electrode were used as anode and cathode respectively, and a 250 W ultraviolet lamp (365 nm) as side light source. The SEM results of TiO2/C and Ti/SnO2+Sb2O3/PbO2 anode indicated that the TiO2 on carbon particles was uniform and PbO2 film on the surface of anode was in cauliflower form, the XRD result of oxygen diffusion electrode showed that only crystalline graphite was found. The influential parameters of degradation process such as applied cell voltage (E), initial concentration of phenol (C0), amount of TiO2 catalyst and air flow rate (v) were discussed. Under the following experimental conditions of C0=50 mg/L, pH=6, E=2 V, TiO2 0.98 mg/mL, v=382.2 mL/min, and light intensity I=10.5 mW/cm2, phenol could be entirely degraded, and about 89% of total organic carbon (TOC) was removed after 3 h degradation.

Pre-reduction of Fine Iron Ore with Moving Bed at Low Temperatures and Behavior of Carbon Deposition

REN Dong-xia LI Qiu-ju WANG Dao-jing HONG Xin

. 2009, 9(5):  922-926. 

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Pre-reduction of fine iron ore at low temperatures was studied with single factor and orthogonal experiments. The effects of ratio of gas to solid, reaction time, temperature of furnace, particle size and kind of reducing agent on the reduction degree of fine iron ore were examined respectively. The process parameters were optimized and the behavior of carbon deposition was also discussed. The experimental result showed that the particle size of 14~20 mm, temperature of furnace in the range 660~700℃, reaction time between 180~220 s, and kind of reducing agent CO 0~20%(j) were the optimal conditions, and the maximal reduction degree of 70.16% was achieved. In addition, the XRD and chemical analysis of reduction product indicated that the carbon deposition occurred during the reduction process. The presence of hydrogen could accelerate the carbon deposition rate.

Crystallization Conditions of Ammonium Aluminum Sulfate from Acid Leachate of the Ash Containing Vanadium

XU Yao-bing WANG Qin-hui SHI Zheng-lun FANG Meng-xiang GAO Xiang LUO Zhong-yang

. 2009, 9(5):  927-931. 

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In order to obtain optimal processing conditions of extracted ammonium aluminum sulfate from the acid leaching solution, orthogonal experiments were conducted to study the effects of concentration of aluminum sulfate, molar ratio of ammonium to aluminum, cooling rate and crystallization temperature on the crystallization rate of ammonium aluminum sulfate. Compositions of the leachate and ammonium aluminum sulfate were measured, and the crystallization rate was calculated. The results show that all of the four factors have obviously influences on the crystallization rate, and the concentration of aluminum sulfate and molar ratio of ammonium to aluminum are prominent comparatively. Their optimal conditions obtained as followed: concentration of aluminum sulfate is between 150 and 200 g/L, molar ratio of ammonium to aluminum about 1.2, cooling rate about 15℃/h, and crystallization temperature about 5℃. With the conditions, the crystallization rate of ammonium aluminum sulfate is 89.32%.

系统与集成

Tri-adsorber TSA Purification System and Its Energy Saving Effect in Air Separation Unit

ZHANG Pei-kun WANG Li LIU Gui-qin LI Zheng-qiang YANG Bing-biao GUO Gui-bin

. 2009, 9(5):  932-939. 

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In order to reuse waste heat of present bi-adsorber purification system, a new tri-adsorber system was proposed to reuse the residual energy of the discharged purge gas. Energy efficiency and economic feasibility of this new system were analyzed. By general analysis and computation, the prospective rates of energy-saving could reach 58.6% and 46.1% respectively if this tri-adsorber system was applied in 20000 and 21000 Nm3/h air separation units (ASU) from two factories. An air purification temperature swing adsorption (TSA) simulator for ASUs based on Aranovich-Donohue adsorption isotherm and linear driving force (LDF) mass transfer assumed non-adiabatic adsorption model was developed, the model parameters were determined by matching monitoring curves obtained from locale industry. Safety and energy-saving effect were proved through numerical simulation if tri-adsorber TSA system was applied in No.6 ASU of Baosteel Co., Ltd., the rate of energy-saving was 45%.

Simulation of Partial Oxidation of Methane to Acetylene with Detailed Reaction Mechanism

CAO Su WANG Tie-feng

. 2009, 9(5):  940-946. 

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The non-catalytic partial oxidation of methane to acetylene was simulated with Curran detailed reaction mechanism using CHEMKIN software. Under the industrial relevant operating conditions of preheating temperature 873 K and oxygen/methane molar ratio 0.55, the simulated maximum acetylene concentration was 7.6%(mol), in agreement with the industrial data. The effects of operation parameters, such as oxygen/methane molar ratio, preheating temperature and reaction time, on the ignition delay time and species concentrations, were investigated. The simulation results show that there is an optimal oxygen/methane molar ratio to get the maximum acetylene concentration at a given preheating temperature. The maximum acetylene concentration can be notably enhanced by increasing the preheating temperature: the maximum acetylene concentration was 7.8%(mol) at preheating temperature 823 K, and was 8.4%(mol) at preheating temperature 1023 K. The acetylene concentration deceased rapidly after reaching its maximum, therefore the product mixture must be quickly quenched at the position of maximum acetylene concentration to get a maximum acetylene yield.

Techno-economic Analysis on Bioconversion of Glycerol into 1,3-Propanediol

MOU Xiao-jia TENG Hu SUN Ya-qin XIU Zhi-long

. 2009, 9(5):  947-952. 

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The continuous bioconversion of glycerol into 1,3-propanediol was analyzed via modeling and optimizing the fermentation and separation process. The highest concentrations, productivities and yields of 1,3-propanediol under various operational conditions were calculated, coupling with the economic evaluation of the cost of energy and materials. The results indicated that the increase in the productivity would not simultaneously bring more profits, but the opposite, the increase in the yield of 1,3-propanediol to glycerol would bring growth to the profit, but this growth became slow once the yield was higher than 0.68 mol/mol. The economic sensitivity showed that the cost of glycerol was the key factor influencing the profit. Through applying the integrated production of biodiesel and 1,3-propanediol, the cost of glycerol could be saved while the retained profit was increased by 31%.

生化工程专栏

Preparation of Large Size Agarose Beads by Microporous Membrane Emulsification Technique

LIN Nan WU Jie ZHENG Guo-jun MA Guang-hui SU Zhi-guo

. 2009, 9(5):  953-961. 

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With 6% agarose solution as water phase, composed by liquid paraffin (LP) and petroleum ether (PE) with different volumetric ratios as oil phase, and PO-5S as emulsifier, agarose beads with average size of 90 mm were prepared by membrane emulsification, and the effects of pore size of the shirasu porous glass (SPG) membranes, oil phase composition, temperature and pressure on the size and size distribution of prepared agarose beads were investigated. The optimal preparation conditions were: the pore size of used SPG membrane was 25.9 mm, oil phase composed by volumetric ratio of LP and PE 11:1 and the preparation temperature 65℃. The prepared agarose beads with good reproducibility had an average diameter of 93.3 mm, size distribution index, Rspan, 1.25 and relative standard deviation 1.34%.

Biodegradation of Tetracycline Antibiotics Residues in Swine Manure

SHEN Ying WEI Yuan-song ZHENG Jia-xi FANG Yun CHEN Li-ping

. 2009, 9(5):  962-968. 

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L9(34) orthogonal experiments by simulating the aerated static pile process were carried out to investigate the biodegradation of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) residues in swine manure at different incubation temperatures (35.0, 45.0 and 55.0℃), initial moisture contents (40.0%, 60.0% and 75.0%) and time (7, 14 and 21 d). Meanwhile, the microbial community of total heterotrophic microorganisms was analyzed by standard dilution plating of incubation at 28, 45 and 55℃, respectively, for 4 d. The results showed that the biodegradation rates of these three tetracyclines (TCs) would reach the maximum at the conditions of 55.0℃, 60.0% and 14 d. The biodegradation of TCs in swine manure met with the first order kinetics model. Statistical analysis showed that temperature was the major factor of OTC and TC biodegradation, and initial moisture content was the major factor of CTC biodegradation, however, these three factors did not have a significant effect on the biodegradation rate of these TCs and relative ratio of fungi, actinomycete and bacteria, respectively. The bacteria were the predominance during the biodegradation of TCs residue in swine manure.

Purification of Chlorogenic Acid from Honeysuckle by Oligo-b-cyclodextrin Coupled Sepharose HP Column

ZHANG Yi-min LIU Jun-feng;

. 2009, 9(5):  969-974. 

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An epichlorohydrin polymerized b-cyclodextrin ligand coupled to brominated allyl-group substituted Sepharose HP was used for one-step purification of chlorogenic acid from honeysuckle. The experimental conditions, such as mobile phase, temperature, loading capacity, on the separation were optimized. The separation conditions were optimized. The optimized mobile phase was H2O-ethanol- acetic acid (85:10:5) with the flow rate of 1.0 mL/min. The loading capacity of the wet gel was 0.5 mg/mL (wet gel) for samples. The effect of temperature was discussed, the mechanism of separation was confirmed by adding urea and SDS respectively into the mobile phase. Adopting the optimum mobile phase, a chlorogenic acid purity of about 97% with a recovery rate of approximate 65% could be achieved by proper peak cutting. The result was affirmed by MS spectra. The column could be reused for 10 times with good separation. Full separation efficiency could be restored by cleaning the column with 0.3 mol/L NaOH followed by distilled water and 30% acetic acid.

Synthesis and Characterization of 8-(6-Aminohexyl)-amino-NADH

MA Hong-jing WANG Ping SU Zhi-guo ZHANG Song-ping

. 2009, 9(5):  975-980. 

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8-(6-aminohexyl)-amino-NADH was successfully prepared by modifying NADH with 1,6-hexanediamine at the C8 position of adenine moiety. After 3-step synthesizing process, the product was purified on DEAE-Sepharose column with the final yield up to 60%. The stability of NH2(CH2)6NH-NADH in acid or neutral environment was studied and compared with the native NADH. The results showed that the modified NADH was more stable than the native one, particularly in the citric acid-sodium citrate buffer (pH 6.5) and phosphate buffer (pH 8.0), the half life of modified NADH increased 11.0 folds and 5.0 folds, respectively. Catalytic activity of the modified NADH was evaluated with lactate dehydrogenase (LDH) and glutamate dehydrogenase (GDH) systems. For LDH and GDH, the activity for NH2(CH2)6NH-NADH was 3.0~3.8 or 1.3~1.4 times higher than that of native NADH, respectively.

Expression and One-step Purification of Recombinant Glucosidase in Pichia pastoris

ZHOU Jin YIN Peng

. 2009, 9(5):  981-986. 

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The bg gene encoding an extracellular glucosidase from Trichoderma viride was cloned into vector pPIC9k-His6 and expressed in Pichia pastoris GS115 strain under the control of AOX 1 promoter. After 120 h of 5 L-scaled fermentation, wet cells weight of the recombinant P. pastoris Mut+ strain reached 360.6 g/L, and the glucosidase concentration and enzyme activity in the supernatant were 2.1 mg/mL and 73.5 U/mL, respectively. The activity of glucosidase was improved 42.6 fold by affinity chromatography with a final yield of 73.6% and the specific activity of the purified enzyme was 71.9 U/mg. The purified glucosidase, analyzed by SDS-PAGE and western blotting, showed only one homogeneous band and the purity was 95.6% by HPLC. The pI of the enzyme was 5.0. Then the factors affecting the glucosidase activity were evaluated. The optimal temperature and pH were 50℃ and pH 6.5, respectively. Metallic ions Ag+, Ca2+, Cu2+, Fe2+, and SDS could inhibit the enzyme activity, whereas 1 mol/L Mg2+ enhanced 120% of the enzyme activity.

Effect of Solid Content on Start-up of Mesophilic Middle Solid Anaerobic Digestion for Water-sorted Organic Fraction of Municipal Solid Waste

FANG Wei SUN Yong-ming YUAN Zhen-hong

. 2009, 9(5):  987-992. 

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Using water sorted organic fraction of municipal solid waste (WS-OFMSW) as materials, pilot scale (35 L) mesophilic [(30±2)℃] middle solid batch anaerobic digestions were carried out to investigate the effects of reactor total solids (TSr 16.0%, 13.5% and 11.0%) on start-up stability and performance of anaerobic digestion. The experimental results showed that all of three TSr could start up without inhibitions of VFAs and ammonia. The "inhibited steady state" was not found. The anaerobic digestion systems had the ability of self-saving. During the period of start-up, the pH value increased gradually and then kept in neutral. The free VFAs and free ammonia concentrations were lower than 50 and 6 mg/L respectively which were lower than inhibition levels of methane production. The low TSr was favorable for rapid start-up and shortening the period of anaerobic digestion. The peaks of methane productions were found at 32, 25 and 12 d for TSr at 16.0%, 13.5% and 11.0% respectively. The lag time of start-up was10.8, 5.6 and 1.9 d.

Direct Biotransformation of Dioscorea zingiberensis C.H. Wright by Aspergillus oryzae to Produce Diosgenin

DONG Yue-sheng QI Shan-shan LIU Lin XIU Zhi-long

. 2009, 9(5):  993-998. 

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The pH, biomass inoculation, and culture temperature were proved to be the main factors in direct biotransformation of steroidal saponins in Dioscorea zingiberensis C.H. Wright by Aspergillus oryzae to produce diosgenin. Under the transformation conditions of 66.7 mmol/L Na2HPO4-KH2PO4 buffer with pH 6.0, 8% biomass inoculation, culturing at 37℃ for 84 h, then 50℃ for 8 h, the highest yield of diosgenin was 17.06 mg/g, which was 6.77 times to that of crude enzyme transformation. Biotransformation of D. zingiberensis by A. oryzae could raise total moles of steroidal constituent 1.73 times to that of extract of D. zingiberensis and 1.47 times to that of acid hydrolysis, respectively. The biotransformation product was identified as diosgenin by MS and NMR. Direct biotransformation of Dioscorea zingiberensis raw herb by Aspergillus oryzae was demonstrated to be superior to enzymolysis method.

材料工程专栏

Preparation and Characterization of Ca-Fe-Ce-based Nitrate Flame Retardants

CHEN Jiang-chao HAN Ning ZHANG Dong-hai CHAI Yu-lin LIU Hai-di CHEN Yun-fa

. 2009, 9(5):  999-1004. 

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Novel flame retardants were prepared by mechanochemical method using CaO, Fe(NO3)3×9H20 and Ce(NO3)3×6H2O as starting materials. By means of XRD, TG-DTA and ICP techniques, the obtained products were identified as Ca0.51Fe0.49(OH)2(NO3)0.4×0.69H2O (Ca-Fe LDH) and Ca0.51Fe0.37Ce0.12(OH)2(NO3)0.49×0.59H2O (Ca-Fe-Ce LDH). Using Ca-Fe LDH and Ca-Fe-Ce LDH as flame retardant filler, a series of RTVSR (room temperature vulcanized silicone rubber) composites were prepared. The results showed that when adding 70 g Ca-Fe LDH and Ca-Fe-Ce LDH into 100 g PDMS (polydimethylsiloxane), the tensile strength of the obtained RTV composite was about 4.5 MPa and its LOI (limited oxygen index) near 34.5%. When adding 20 g Ca-Fe-Ce LDH into 100 g PDMS, the resulted composite exhibited excellent smoke inhibition behavior with the smallest smoke density of 8.46.

Preparation of Porous Silica with Simple Organic Template

LIU Hai-di YUE Ren-liang ZHANG Dong-hai WU Zhen-jiang CHEN Yun-fa

. 2009, 9(5):  1005-1010. 

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Porous silica was prepared with simple organic template and tetraethyl-orthosilicate (TEOS) as pore-generating agent and silicon precursor respectively. The influences of dosage of simple organic template upon the specific surface area and pore volume of the as-made porous silica were investigated. BET, SEM and TEM methods were employed to analyze the specific surface area and pore structure of the silica samples. A proposed mechanism was developed to explain the pore-forming effect of the simple organic template on the porous silica. Parallel experiments with base-silica-sol used as silicon precursor were also conducted to testify the proposed mechanism. The results indicated that when the dosage of the template was 0.3 g/mL TEOS, the samples with large surface area (>650 m2/g) and high pore volume (>1.0 mL/g) could be successfully prepared, and the pore structure was amorphous. It is highly possible that the amorphous pores are generated by the simple organic template which was mixed with TEOS polymer in molecular scale and was burnt away in the following calcination process.

Synthesis of B4C-C Composite Powder and Its Application in Low Carbon MgO-C Bricks

YAN Zheng-guo; CHEN Wei; YU Jing-kun

. 2009, 9(5):  1011-1016. 

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B4C-C composite powder was synthesized from carbon black and boric acid by carbothermal reduction reaction. The effect of heating temperature on the synthesis of B4C-C composite powder was studied. The phase composition, morphology, structure and particle size of synthesized composite powder were characterized by XRD, carbon and sulfur analyzer, SEM, and laser particle size analyzer. The effects of the synthesized composite powder added in MgO-C brick were investigated by measuring the physical properties, oxidation resistance, and thermal shock resistance of specimens. The results show that the graphitization degree of the synthesized B4C-C composite powder rises, while B4C phase decreases with increasing of heating temperature. The graphitization degree of the composite powder synthesized at 1900℃ is 23.26%, the percentage of B4C is about 20%. The differential distribution of the synthesized composite powder is above 85% nanometer B4C and partly graphitized carbon black, except some micron and submicron B4C particles. The physical properties, oxidation resistance, and thermal shock resistance of the low carbon MgO-C brick specimens added with the synthesized B4C-C composite powder are excellent.

Influences of Process Parameters on Preparation of Foam Glass from Iron Ore Tailings

ZHANG Shu-hui; XUE Xiang-xin ZHANG Shu-qing

. 2009, 9(5):  1017-1022. 

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Foam glass with good capabilities was prepared from iron ore tailings with CaCO3 and Na2CO3 as blister, sodium phosphate and borax as stabilizer. The influences of different process parameters on sample capabilities were also studied. The results show that CaCO3 is the main blister, and Na2CO3 content has little effect on sample capabilities. Sodium phosphate is the main stabilizer, while the borax content should not be high. With the increase of foaming temperature the diameter size of sample increase, while bulk density and compression strength are reduced. The bulk density and compression strength all decrease firstly and increase subsequently when the sintering temperature increases. The optimal process parameters of preparation of foam glass are basic glass content 84%, CaCO3 3%, Na2CO3 2%, sodium phosphate 8%, borax 3%(w), foaming temperature 900~950℃, and sintering temperature 1100℃. Under above conditions, foam glass is made with bulk density 2.05 g/cm3 and compression strength around 62 MPa.

Porous Structure and Fractal Characteristics of Metal Impregnated Graphite Material

WANG Qi-li HU Ya-fei LIU Qi

. 2009, 9(5):  1023-1027. 

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To quantitatively describe the pore structure of obtained graphite/metal porous materials and study the influence of pore structure on impregnating process, the causes of unimpregnated hole were analyzed based on the formation mechanism of the graphite porous materials, and the pore structure was studied using fractal theory. The results show that micro-pore structure of the graphite/metal porous materials has typical fractal characteristics. The fractal dimension of matrix ranges from 1.80 to 1.85, the fractal dimension of pores from 1.55 to 1.65, the fractal dimension of impregnated metal from 1.50 to 1.55, and the fractal dimension of unimpregnated area from 1.42 to 1.60. The fractal dimensions indicate the heterogeneity of the micro-pore structure and the porosity shows similar changes to the fractal dimension using the mercury injection test. Consequently, the fractal dimensions can be used to characterize the porosity of graphite/metal porous materials.

综述

Progress in Preparation of Microspheres Using Microfluidic Devices

ZHANG Yan LEI Jian-du LEI Jian-du MA Guang-hui SU Zhi-guo MA Guang-hui; SU Zhi-guo;

. 2009, 9(5):  1028-1034. 

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Compared with traditional mechanical mixing method, monodisperse and uniform microspheres with controllable morphology can be obtained by microfluidic technology. The mechanism of this technology and its applications in the fields of drug carrier, cell carrier, separation matrix, food manufacturing and enzymology are reviewed. In addition, the effects of material and shape of microfluidic device, property of liquids used for experiment on the formation of particles are mainly discussed. Avoiding phase inversion by modifying the inner wall of microchannel and controlling continuous phase are pointed. Moreover, controlling the shape of microspheres by means of changing the dimensions of microchannels and continuous phases are also shown. Furthermore, some novel prospects of this promising technology are briefly discussed.

Research Advance in Thermal Recovery of Natural Gas Hydrate

SONG Yong-chen RUAN Xu-ke LIANG Hai-feng LI Qing-ping ZHAO Yue-chao

. 2009, 9(5):  1035-1040. 

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The thermal recovery method, as one of alternative exploitation schemes for natural gas hydrates in future，has attracted more attentions. This paper has reviewed the advance on the thermal recovery of gas hydrate in both basal experiment researches and numerical simulation. The decomposition kinetics of hydrate, effects of heat transfer and mass transfer on the dissociation, and the production principles in porous media and hydrate reservoir all are elaborated. Thermal recovery technology as a method of enhanced heat production could make up the disadvantage of general exploitation with low efficiency. Although the experimental study of thermodynamics and kinetics of hydrate dissociation has been well improved to interpret the thermal decomposition behaviors, the research on thermal properties of hydrate-bearing sediment is still absent. The numerical models, developed from single-phase 1D to complex multi-phase 3D, are able to achieve simulation of accurately field-scale hydrate reservoir. Finally, the research direction of gas hydrate by thermal stimulation is also pointed.