Table of Content

20 June 2010, Volume 10 Issue 3

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流动与传递

Numerical Simulation on Aerodynamic Heating and Thermal Stress of ZrB2-SiC Leading Edge

LIN Xiao-xuan WU Hai-tang WEI Xi SHEN Zhi-xun; ZHANG Wei-gang;

. 2010, 10(3):  417-423. 

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Aerodynamic heating process and thermal stress of ZrB2-SiC leading edge as the component of scramjet engines were numerically investigated by finite-difference and finite-element methods, and the simulation results were verified through thermal structure tests with arc-heated wind tunnels. Simulation results showed that the temperature at stagnation point reached 1870 K in 5 s, and thermal stress of structure was up to 1240 MPa which was beyond the fracture strength of ZrB2-SiC material, when the inflow Mach number was 6, total pressure 4.41 MPa, total temperature 2375 K, with the radius of leading edge at 0.125 mm. The experimental results show that the temperature at stagnation point reached 2175 K in 5 s, and the leading edge cracked in thermal structure tests. Simulation results were in reasonable agreement with the experimental results.

Power Demand and Mixing Performance of Coaxial Mixers in Newtonian Liquids

XIE Yong BAO Yu-yun LIU Tao ZHANG Zhong-dong GAO Xiong-hou;

. 2010, 10(3):  424-430. 

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All experiments were carried out in a transparent dished bottom stirred tank with the diameter T of 0.48 m and liquid level of 0.6T. The power consumption and mixing performance of a coaxial mixer consisting of a wall-scraping anchor and different dispersion impellers (CBY, 45o pitched blade turbine and Rushton turbine) operating in co- and counter-rotating modes were experimentally characterized in viscous Newtonian fluids with different viscosities. The results show that for the co-rotating dispersion modes, the power consumption of the anchor could decrease up to 10% of that for anchor rotating only, whereas for the counter-rotating dispersion ones, it could increase 2 times of that for anchor rotating only. The power consumption of the dispersion impellers is almost independent of the anchor rotation. The new correlations based on the impeller geometry and speed ratios for the generalized Reynolds number and the power number are proposed, and a reasonable power curve can be generated for different experimental speed ratios of each system. Impellers in co-rotating mode are more efficient than the counter-rotating ones in the mixing of the Newtonian fluids. Among above three dispersion impellers, the power consumption of the CBY impeller-anchor combination is about 20% to 30% of that for other two combinations given the similar mixing performance.

Acting Forces and Agglomerate Sizes of Super Fine Particles in an Acoustic Fluidized Bed

SU Ji ZHU Qing-shan

. 2010, 10(3):  431-437. 

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Super fine iron ore particles (7.4 mm) were fluidized in a 40 mm i.d. fluidized bed with sound excitation. The results showed that the size of agglomerate was decreased with increasing the sound pressure level. At a given sound pressure level, there existed an optimal sound frequency of 130 Hz in this work. A force balance model was developed to predict the agglomerate size through analyzing the forces acting on the agglomerates based on the assumption that the agglomerate will reach a stable size when the detached forces and adherent forces acting on the agglomerate are equal. The agglomerate size is predicted to be 367 mm by the model at the sound pressure level of 120.5 db and the sound frequency of 130 Hz, which is in good agreement with the size of 384 mm calculated from the minimum fluidized velocity under the same condition.

Effects of Operating Conditions on Asymmetric Vortex in Continuous Casting of Slab

WANG Zhi-guo ZHANG Xiao-wei; WANG Yin; WANG Min; DENG Kang; REN Zhong-ming;

. 2010, 10(3):  438-444. 

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The experiments of water model were conducted to study the effects of technical parameters on surface vortex in the mold of continuous casting of slab using plexiglass water model. The results indicate that the causes of vortex lie in two aspects. The turbulence of surface flow gives rise to asymmetry of flow momentum near the SEN, and operating parameters cause the asymmetry of the surface flow besides the SEN. In the case of the same casting speed the full open of slide gate causes 7~9 fewer times vortexes on the surface than partial open, and the increase of SEN length under slide gate has a limited effect on decrease of vortex frequency. As the rise of SEN one outlet clogging, the frequency of vortex increases rapidly. When one outlet clogging degree is 70% and slide gate opening degree are 40% and 60%, the vortex frequency are about 2.2 and 2.9 times of that without clogging.

Fluidization Washing of the Red Mud

LI Xiao-bin LI Bin PENG Zhi-hong LIU Gui-hua ZHOU Qiu-sheng QI Tian-gui

. 2010, 10(3):  445-450. 

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The fluidization-washing experiments of Bayer red mud were conducted using the fluidization apparatus based on the principle of fluidization. The results show that Na2O concentration and mass ratio of liquid to solid in the underflow can reach 0.25~5 g/L and 2.2~2.7, respectively, and Na2O concentration of the overflow is 90~150 g/L, when the Na2O concentration of the red mud slurry is 125~180 g/L and the amount of washing water used is 4.2~4.9 t/t-red mud. A mathematical model was developed based on the principle of fluidization washing, which can predict the washing effect and the axial concentration distribution in the fluidization washing process. The fluidization technology can achieve the washing effect with many advantages

Migration of Amino Acids in Bipolar Membrane Electrodialysis Process of Lactic Acid Fermentation Broth

WANG Li-jing YANG Peng-bo WU Xia CONG Wei LI Chun

. 2010, 10(3):  451-456. 

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Migration of amino acids concurrently with lactic acid from the feed cell to the acid cell in the three-compartment bipolar-membrane electrodialysis (BMED) process of lactic acid fermentation broth influences the purity of recovered lactic acid. Amino acid migration phenomenon and its rules were investigated in the bipolar-membrane electrodialysis process of lactic acid fermentation broth. The results showed that migration velocity of amino acid was mainly influenced by amino acid concentration, the difference between its pI and the environmental pH, the selectivity of anion exchange membrane to the amino acid anion, and the ionic mobility of amino acid anion. Based on this migration rule, an ionic migration velocity calculation model was developed and validated by comparing it with practical BMED process. The result of a process applying the calculation model showed that migration rate of total amino acids being 32.5% was 60.7% lower than the controlled experiment of 82.6%. Higher lactic acid purity via BMED could be achieved by regulating hydrogen leakage to control the pH in the feed cell and improving the selectivity of anion exchange membrane to lactic acid anion.

Effect of Electrolyte on Gas-Liquid Dispersion in a Gas-Liquid Stirred Reactor

ZHAO Jian-chu BAO Yu-yun GAO Zheng-ming

. 2010, 10(3):  457-461. 

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Experiments were conducted in a triple-impeller stirred tank of 0.48 m diameter with a dished base to investigate the effect of electrolyte on gas holdup and power consumption. The impeller configuration consisted of a half elliptical disk turbine (HEDT) as the bottom and two up-pumping wide-blade hydrofoils (WHU) above HEDT. Air was used as the dispersed phase and aqueous solutions of Na2SO4 from 0.05 to 0.5 mol/L were used as the continuous phase. The results show that the concentration of Na2SO4 solution has great effect on the hydrodynamic characteristics, gas holdup increases significantly with the increase of concentration, the gas hold-up in 0.5 mol/L Na2SO4 solution is up to 40% more than that in the deionized water system. Pg/P0 decreases with the increase of concentration. It also shows that the influence of temperature is relatively weak in electrolytic solution. The gas holdup in 0.4 mol/L Na2SO4 solution at 68℃ is 11% less than that at 24℃, while it decreases more than 40% from 24 to 68℃ in deionized water system.

反应与分离

Treatment of Wastewater Containing Phenol with H-103 Macroporous Resin

ZHOU Li ZHONG Hong LI Chao ZHAO Gang

. 2010, 10(3):  462-469. 

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The removal of phenol from 600~1000 mg/L aqueous phenol solution was investigated using macroporous resins. The effects of initial concentration, pH and temperature on phenol removal were studied. The experimental results indicated that the adsorption reached equilibrium state within 20 min, and adsorption kinetics could be well described by the pseudo-second-order kinetic model. Langmuir isotherm model was better to describe the isothermal adsorption of phenol onto the macroporous resin, the saturated adsorption capacity (Qm) and Langmuir constant (KL) were 86.00 mg/g and 0.2719 L/mg, respectively. Experimental results of desorption for the resin after reaching saturation station showed that it had better desorption properties. Macroporous resin H-103 was an excellent reusing adsorption material, which can remarkably remove phenol from aqueous solution.

Dealkalization of Red Mud Generated in Alumina Production by Sub-molten Salt Process under Atmospheric Pressure

CHEN Li-bin ZHANG Yi-fei WANG Shao-na

. 2010, 10(3):  470-475. 

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The dealkalization of red mud from sub-molten salt process under atmospheric pressure and low temperature was investigated. The effects of temperature, CaO addition, Na2O concentration of solution and time on the process were examined. The experimental results indicated that the content of Na2O in the final red mud decreased with the increase of CaO addition, reaction temperature and reaction time, but not so as to the initial concentration of Na2O in the NaOH solution, and it could be as low as 1.41% while mass ratio of Na2O to SiO2 was decreased to 0.07 when dealkalizing in 60 g/L Na2O solution with mass ratio of CaO to red mud 0.22 at 95℃ for 10 h. After leaching under the above conditions, the new phase of calcium silicate formed, and the morphology of the red mud changed from rod-like crystals to fluffy agglomerate with flakes.

Phase Equilibrium Measurement and Prediction of Cyclopentane-Methane Hydrates in NaCl Aqueous Solution

YAN Zhong-yuan CHEN Zhao-yang LI Xiao-sen LI Qing-ping YAN Ke-feng

. 2010, 10(3):  476-481. 

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Isothermal pressure search method was used to measure the phase equilibrium conditions of cyclopentane (CP)-methane hydrates in the temperature range from 84.4 to 303.8 K and the NaCl mass concentration range from 0 to 10%. The results indicate that the equilibrium pressures of structure II hydrates of CP-methane are lower than that of methane hydrate. The phase equilibrium pressures of CP-methane hydrates increase with the increase of temperature, and increase linearly with the increase of NaCl concentration in solutions. Moreover, the effects of temperature and NaCl concentration are enlarged at a high temperature. A calculation and prediction model for equilibrium conditions of CP-methane (structure II) hydrates has been developed based on Van der Waals-Platteeuw isothermal adsorption theory and Pitzer activity coefficient model. The prediction results show that the model can depict the equilibrium conditions of CP-methane (structure II) hydrates well (average relative error at 4.07%).

Effect of Copper Ions on Deep Removal of Cobalt from Zinc Sulfate Solution

ZHAO Guang-ming LI Xiang-yang ZHANG Guang-ji YANG Chao

. 2010, 10(3):  482-487. 

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The effect of copper ion, Cu2+, on deep deletion of cobalt from zinc sulfate solution was studied comprehensively by several criteria, including the time when cobalt concentration reaches 0.1 mg/L, the time of duration when cobalt concentration is below 0.1 mg/L and the initial concentration of copper ion guaranteeing deep removal of cobalt. The best results are respectively obtained under the optimal conditions of addition of [Cu2+]0 200 mg/L, mass ratio of Co and Sb (Co/Sb) at 2:1, at 25 min [Co2+] dropped to 0.1 mg/L and lasting 70 min for the solution with [Co2+]0=15 mg/L, and addition of [Cu2+]0 100 mg/L, Co/Sb=2:1, at 40 min [Co2+] dropped to 0.1 mg/L and lasting 55 min for [Co2+]0 of 7.5 mg/L. The agitation speed has little effect on cobalt removal and even promotes redissolution. The analysis results by energy spectrum indicate that the cobalt redissolution is probably due to the dissolution of basic cobalt salt.

Studies on Purification of Solvent Naphtha with Ceramic Membrane

ZENG Jian-xian ZHENG Li-feng YE Hong-qi SUN Xia-hui HE Qin-cheng

. 2010, 10(3):  488-492. 

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The microfiltration process of solvent naphtha containing impurities was studied with a ceramic membrane of average pore diameter 0.2 mm. Both feeds of solvent naphtha without water and solvent naphtha containing 0.5%(w) water were selected. The effects of operating time, trans-membrane pressure, cross-flow velocity, temperature and aluminum powder content on permeate flux and aluminum powder rejection were investigated, respectively. Furthermore, backflushing experiment, concentration experiment and cleaning of fouled membrane were also studied. The results show that permeate flux of solvent naphtha without water is much higher than that of the solvent naphtha containing 0.5%(w) water. With increasing operating time, permeate flux decreases gradually to a steady value, and the rejection of aluminum powder increases rapidly to 100%. Steady-state flux is enhanced with increasing trans-membrane pressure or temperature, and increased to a maximum value with the increase of cross-flow velocity. The higher the content of aluminum powder, the higher the permeate flux. Optimum operating parameters are trans-membrane pressure 0.16 MPa, cross-flow velocity 3.9 m/s and temperature 40℃. The backflushing can increase efficiently permeate flux. In the process of concentration, permeate flux decreases to a steady value, and then decreases rapidly. Purified solvent naphtha is transparent. In addition, permeate flux could be recovered effectively to 94.9% of new membrane flux by using 0.15%(w) commercial detergent and 0.25%(w) nitric acid, respectively.

Removal of Low Concentration Protein from Water Using Horizontal Pressure Air-dissolving Foam Separation

DONG Hong-xing YUE Guo-jun LIU Wen-xin ZENG Jing-jiang DING Qian-kun ZHANG Jin;

. 2010, 10(3):  493-497. 

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The foam separation process was conducted with a stimulated system using soya protein as target protein, and horizontal foam separation as device. The effects of flow rate of raw material, pH value, flow rate of dissolved gas water on the removal efficiency of protein were investigated. And the advantage of horizontal foam separation device for removing protein in water was analyzed from the process engineering perspective according to protein structure. The results revealed that under the optimal conditions the concentration of the raw material at 8 mg/L, flow rate of raw material 50 L/h, pH value 4.5, and flow rate of dissolved gas water 275 L/h. Under these conditions, the removal rate can reach up to 90.5%.

Microwave-assisted Extraction of Lactone from Ligusticum Chuanxiong Hort Using Ionic Liquid

ZHANG Zhi-da CHEN Ji-ping LI Chang-ping YAN Pei-fang WANG An-jie Urs Welz-Biermann

. 2010, 10(3):  498-502. 

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A microwave-assisted extraction (MAE) method was used to extract Senkyunolide I, Senkyunolide H and Z-ligustilide from Ligusticum Chuanxiong Hort. Ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim]Tf2N), was employed as extractant. Influential factors such as system temperature, extraction time, phase ratio and particle size were examined. The yield of the three target ingredients was compared between MAE and solvent reflux extraction (SRE), and the sample matrix was studied by SEM. The result shows that temperature is the key factor of extraction process, the best result is obtained at 180℃. Extraction equilibrium can be reached within 1 min. Phase ratio (solid/liquid) and particle size do not make contribution to the extraction efficiency within the limits of 1/30~1/5 g/mL for phase ratio and 0.096~0.25 mm particle sizes. Compared with SRE, MAE costs less time and gives higher extraction efficiency, an increase of 46% was reached for Z-ligustilide, because the structure of Ligusticum Chuanxiong Hort was damaged, as shown by SEM images, which was beneficial to the extraction of natural products.

Adsorption of Congo Red from Aqueous Solution by Zr-Al Pillared Bentonite Synthesized under Microwave Irradiation

WEI Ke-lu TANG Yan-kui TONG Zhang-fa LONG Min LIANG Da-wen

. 2010, 10(3):  503-507. 

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Zr-Al pillared bentonite synthesized under microwave irradiation (MZAPB) was used as adsorbent for removal of Congo Red from wastewater. The MZAPB was characterized by XRD and FT-IR before and after adsorption of Congo Red to evaluate the possible mechanism of adsorption. The experimental results reveal that the removal rate of Congo Red can reach 97.64%, while the adsorption capacity is 12.17 mg/g, and the adsorption reaches equilibrium in 45 min when initial concentration of Congo Red is 50 mg/L, pH 5.6 and adsorbent dosage 4 g/L. The kinetic parameters of the adsorption show that the adsorption kinetics follows a pseudo-second-order model and the intraparticle diffusion is not the only rate controlling step. The Langmuir model yields a much better fitting than the Freundlich model. XRD and FT-IR data show that the physical adsorption is dominant.

Effect of Bubble Diameter on Separation of Butyl Acetate from Simulated Wastewater with Solvent Sublation

WANG Sen-jian CHANG Zhi-dong; MA Yin-chen YU Pin-hua; LIU Hui-zhou

. 2010, 10(3):  508-512. 

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Removal of butyl acetate (BA) from model wastewater (0.40%, j) through solvent sublation method into n-nonane was studied, and n-nonane was used as the upper collecting solvent. The effects of operation variables, such as contact time, gas flow rate, volume ratio of n-nonane to wastewater and the bubble diameter, on the removal efficiency were explored, among which the effect of bubble size was emphasized. The results indicated that the final separation efficiency reached as high as 60% with a electrolysis gas flow rate of 1.67 mL/min and bubble diameter of 0.2 mm, when the gas flow rate was 20 mL/min and the diameter of bubble was 0.6 mm, the separation efficiency also could achieve 60%, both with the volume ratio of n-nonane to wastewater 1:25. But the separation time, total gas volume and secondary pollution caused by n-nonane had great difference.

过程与工艺

Removal of Silicon and Aluminum from EAF Titanium-containing Slag and Pre-oxidization Roasting Kinetics of the Leached Slag

LU Hui XIE Gang YU Xiao-hua XIE Hong-yan

. 2010, 10(3):  513-521. 

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The process route of alkali leaching-oxidative modification at high temperature-high pressure acid leaching for preparing high grade synthetic rutile was proposed for treatment of electric-titanium slag of Yunnan. The removal mechanism of silicon and aluminum from EAF titanium-containing slag was studied. The effects of single-factors including stirring speed, particle size, temperature, NaOH concentration, mass ratio of liquid to solid, alkaline reagent on the leaching rate were examined. The leaching rates of SiO2 and Al2O3 reached up to 75% and 50%. The effective sequence of temperature, NaOH concentration, mass ratio of liquid to solid, and time was investigated by orthogonal experiments. The results show that the leaching effect is well under the conditions of NaOH concentration of 1.5 mol/L, mass ratio of liquid to solid of 8, the boiling temperature, and leaching time of 1 h. There are 60% of the rutile TiO2 crystallized from the slag after alkaline leaching by pre-oxidation, the process was controlled by the interfacial chemical reactions under 800℃, the diffusion rate is faster, and the apparent activation energy 12 kJ/mol.

Pore Structure of Low Temperature and Fast Pyrolysis Bituminous Semi-char from Coal Topping Process

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

. 2010, 10(3):  522-529. 

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The pore structure of char derived from Datong bituminous coal after mild pyrolysis at 550, 650, 750 and 850℃ in a spout entrained reactor was studied using N2 adsorption. The results show that pore structure of all char samples is inferior to that of the parent coal. Yield of volatiles (Y) at four pyrolysis temperatures, 550, 650, 750 and 850℃, are 7.89%, 21.79%, 22.12% and 39.33% respectively. With increasing of Y, mesopore size decreases, micropore and macropore size, as well as total pore volume (Vtotal) and total pore specific area (Stotal), basically increase. At 550℃, volatile release has little contribution to pore structure evolution of char. Relative pressure ranges obtained are used to calculate BET specific surface area (SBET) for parent coal and four chars (derived at 550, 650, 750 and 850℃), are 0.101~0.351, 0.093~0.201, 0.072~0.152, 0.032~0.053, 0.058~0.108 respectively. The change of SBET with pyrolysis temperature is the same as that of Stotal.

Experimental Study on Fast Pyrolysis of Bituminous Coals by Solid Heat Carrier at Low Temperature

ZHANG Meng-die WANG Ze ZHANG Xi-wen WANG Li-chang LIN Wei-gang SONG Wen-li

. 2010, 10(3):  530-535. 

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The pyrolysis of Gaocheng and Fugu coals in the temperature range from 460 to 520℃, heated by solid heat carrier of quartz sand, was investigated in a continuous pyrolytic apparatus. The yields, composition and characteristics of gas and liquid products were analyzed. The results show that within the temperature range, the yields of gas and liquid increase with increasing pyrolytic temperature, and the maximum liquid yield is about 12%. The gas composition obviously varies with pyrolytic temperature, and the heating value of coal gas is above 25 MJ/m3. The tar is in abundance of phenol derivatives, polycyclic aromatic hydrocarbons, benzene derivatives, and chain hydrocarbons are also found at higher content. The content of benzene derivatives increases with increasing temperature, but the content of phenols decreases with it. Based on the results, a simplified reaction route from phenol derivatives to aromatics has been proposed.

Experimental Study on Non-catalytic Partial Oxidation of Methane to Acetylene and Syngas

LI Qing-xun LIU Ye-fei WANG Tie-feng

. 2010, 10(3):  536-541. 

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The non-catalytic partial oxidation of methane under fuel-rich conditions was studied in a nozzle type reactor. The influences of preheating temperature, molar ratio of oxygen to CH4 and ethane and propane addition on the process were studied. The axial concentration profiles of species were measured with a mass spectrometer using a sampling probe that could be moved along the length of the reactor. The molar fraction of acetylene had a maximum value along axial distance, and increasing oxygen ratio led to decreasing of acetylene selectivity. Increasing the preheating temperature is favorable to acetylene production and the concentration of acetylene was 4.52% when preheating temperature reached 620℃. Addition of ethane and propane resulted in the same amount of acetylene with less methane consumption. In the experimental conditions the axial distance of maximum acetylene molar fraction was kept in 80 mm unchanged.

Leaching Kinetics of Pyrolusite Using Cane Molasses as Reductant in Sulfuric Acid Solution

SU Hai-feng CUI Wei SUN Ying-yun LV Xiao-yan WEN Yan-xuan

. 2010, 10(3):  542-547. 

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The leaching kinetics of manganese from a pyrolusite ore by cane molasses as reducing agent in dilute sulfuric acid solution was studied. In order to elucidate the leaching kinetics of manganese, the influences of various parameters were investigated. The results showed that increasing the concentration of sulfuric acid, the concentration of cane molasses and the reaction temperature, or reducing the particle size (r0), could accelerate the leaching rate of manganese. A shrinking core model was used to describe the leaching process, and the kinetic equation was obtained. The leaching process of manganese was controlled by the interfacial chemical reaction. The apparent activation energy was calculated to be 45.6 kJ/mol, and the apparent reaction order was 0.52 and 0.28 for sulfuric acid and cane molasses, respectively.

Leaching Kinetics of Calcium Vanadate by Na2CO3 Solution

LI Wang-xing ZHAO Zhuo SU Zhao-hui; LI Xiao-bin ZHAO Qing-jie

. 2010, 10(3):  548-553. 

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Leaching kinetics of calcium vanadate by Na2CO3 solution was studied. Kinetic equation was established according to the variation of VO3- concentration with time during the leaching process. The influences of initial pH value and stirring speed on reaction rate constant were examined and the corresponding apparent activation energy was calculated. The results indicate that the leaching process is a 0.68 order reaction, and the reaction rate constant 8.64′10-6 mol/(L×s). It increases with the increase of pH value and stirring speed. And the dissolution rate of calcium vanadate also increases. The apparent activation energy is 38.98 kJ/mol, and temperature has great influence on the leaching rate of calcium vanadate.

Hydrometallurgical Electro-oxidation Process of Molybdenum Middlings

XU Hai-qing LIU Dai-yun LIU Hui-yong

. 2010, 10(3):  554-558. 

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The process conditions of hydrometallurgical electro-oxidation process of low-grade molybdenum middlings were studied. The reaction followed a kinetic model with the apparent activation energy of Ea as 16.55 kJ/mol. The optimized process conditions were obtained as follows: temperature of 40℃, slurry concentration of 50 g/L (S/L), current density of 1000 A/m2, NaCl concentration of 100 g/L, and pH value of 10. By electrolysis for 90 min under these conditions, both Mo leaching rate and current efficiency could reach 96.1% and 50.7% respectively.

生化工程专栏

Adsorption Behavior, Bioactivity and Structure of HBsAg on Surface of PLA Microspheres

LI Na WANG Lian-yan; WU You-bin; ZENG Ye-jing; MA Guang-hui SU Zhi-guo

. 2010, 10(3):  559-567. 

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Relatively uniform-sized poly(lactic acid) (PLA) microspheres with the average particle size of 800 nm were successfully prepared by premix membrane emulsification combined with solvent evaporation method. The effects of pH value, salt concentration, amount of PLA microspheres, HBsAg concentration and adsorption temperature on the adsorption efficiency, bioactivity retention and structure of HBsAg were systemically investigated. The results showed that the adsorption efficiency of HBsAg on the surface of PLA microspheres could reach more than 60% under the conditions of pH 6.0 phosphate buffer, 20 g/L NaCl concentration, 20 mg/mL PLA microspheres, 10 mg/mL HBsAg concentration and 37℃ adsorption temperature. The bioactivity retention of HBsAg exceeded 98% under 4℃ with the following conditions: pH value of phosphate buffer at 8.0, concentration of NaCl 1 g/L, amount of microspheres 2 mg/mL and initial HBsAg concentration 300 mg/mL.

Preparation of Microspheres of Paclitaxel-loaded PLA, PLGA and PELA by Premix Membrane Emulsification

ZENG Ye-jing; WANG Lian-yan; MA Guang-hui MA Guang-hui;

. 2010, 10(3):  568-575. 

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Poly(lactic acid) (PLA) microspheres were prepared by premix membrane emulsification and compared with the results by homogenization and ultrasonification. The mean diameters of PLA microspheres prepared by homogenization and ultrasonification were 1.022 and 0.987 mm, and the corresponding polydispersities 0.133, 0.145, respectively, while the mean diameter of PLA microspheres by premix membrane emulsification was 0.906 mm and the polydispersity 0.005. Furthermore, the microspheres of paclitaxel (PTX) loaded PLA, PLGA [poly(lactic-co-glycolic acid)], PELA [poly(ethylene glycol-co-lactide acid)] with uniform size were prepared by premix membrane emulsification, and their encapsulation efficiency and cumulative release profiles in vitro were studied. The mean diameters of PTX-loaded PLA, PLGA and PELA microspheres were 0.906, 0.987 and 1.015 mm with the same polydispersity of 0.005. The corresponding drug loading efficiencies and encapsulation efficiencies were 3.89%, 4.93%, 3.18% and 63.2%, 71.6%, 51.3%, respectively. The cumulative release rates of PLA, PLGA, and PELA microspheres in vitro for 60 d were 83.87%, 50.25% and 41.27%.

Rapid Screening of a Nicotine Acid Hydroxylase Producing Strain and Its Catalytic Conditions

JI Chun-miao; LUO Hui CHANG Yan-hong; ZHOU Bei-hai

. 2010, 10(3):  576-581. 

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A rapid screening method for nicotine acid hydroxylase producing strain was established based on the ultraviolet development. The strain was cultured in 96-well microplate and a drop of broth was detected on the filter paper. The nicotine acid hydroxylase producing strain was screened fast and conveniently by the development of 6-hydroxynicotinic acid under ultraviolet illumination (300 nm). Study on the strain BKC4 with the highest activity showed that it was rod, Gram negative bacterium, and identified as Pseudomonas putida by the analysis of 16S rRNA sequence. The strain of BKC4 was used to convert nicotinic acid to 6-hydroxynicotinic acid. The experimental result showed that the optimal catalytic conditions of BKC4 were 10 g/L of nicotinic acid, temperature 37℃, pH 6.5, 200 r/min of rotation speed, and the enzyme is stable at pH 6.5 and temperature below 30℃.

Optimization of Culture Medium for Growth of B. mucilaginosus PM13 Strain

WANG Xue YUAN Xiao-fan ZHAO Bing WANG Yu-chun

. 2010, 10(3):  582-587. 

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The culture medium optimization of Bacillus mucilaginosus PM13 strain mutated for soil improvement was studied. The effects of the medium composition on the growth of PM13 strain and viscosity of the broth were investigated. The results of single-factor, orthogonal and uniform experiments showed that the varieties of carbon and nitrogen sources affected the growth of PM13 strain and viscosity of the broth significantly. And the ingredients of the optimum culture medium for PM13 growth were (g/L): molasses 3.67, starch 1.83, soybean powder 7.0, CaCO3 8.5, K2HPO4 2.0, MgSO4×7H2O 1.4 and NaCl 0.2. With this culture medium, the production of spores reached 2.2×108 cfu/mL and the fluid consistency coefficient of the broth was markedly decreased to 0.028 Pa×sn, which was suitable for the large-scale fermentation in conventional bioreactors.

Comparison of 2,3-Butanediol Production by Two Klebsiella pneumoniae Strains

SUN Li-hui DAI Jian-ying WANG Xu-dong XIU Zhi-long

. 2010, 10(3):  588-592. 

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The fed-batch fermentation for 2,3-butanediol production by Klebsiella pneumoniae DSM 2026 and CICC 10011 strains was investigated. The results showed that CICC 10011 produced less organic acids and ethanol, but more target products and more yield could be obtained than those of DSM 2026. The final concentration of target products (2,3-BD and acetoin) was 85.61 g/L with a productivity of 1.53 g/(L×h) for 56 h, corresponding to 45% of yield from glucose. Comparison of the metabolic flux distributions between K. pneumoniae CICC 10011 and DSM 2026 showed that K. pneumoniae CICC 10011 is a potential strain for 2,3-BD production.

Modification of Glucagon-like Peptide-1 in Ethanol with Polyethylene Glycol

WANG You-ao; ZHAI Yan-qin LEI Jian-du MA Guang-hui SU Zhi-guo

. 2010, 10(3):  593-597. 

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Glucagon-like peptide-1 (GLP-1) was modified with monomethoxy polye(ethylene glycol succinimidyl carbonate) by using ethanol as a reaction medium. The reaction conditions were investigated and optimized, and the separation procedures of product Mono-PEG-GLP-1 were developed. After that, the stability in vitro and activity in vivo of Mono-PEG-GLP-1 were investigated. The optimized reaction conditions were obtained as follows: concentration of GLP-1 1.0 mg/mL, molar ratio of PEG to GLP-1 1:1, and reaction time 24 h at 37℃. Under the optimized conditions, the yield of Mono-PEG-GLP-1 was up to 77%. The Mono-PEG-GLP-1 was separated from reaction mixture by a preliminary centrifugation under frozen temperature and successive purification by reverse phase chromatography. The purity of Mono-PEG-GLP-1 was higher than 97%, as characterized by size exclusion chromatography. The Mono-PEG-GLP-1 showed better stability in plasma, decreased proteolysis to trypsin and better activity in vivo.

Purification of Oxytocin by Combining Hydrophobic Interaction Chromatography and Hydrophilic Interaction Chromatography

ZHANG Xiao-ou; SONG Mao-qian; WANG Chang-hai Jan-Christer Janson GU Ming

. 2010, 10(3):  598-602. 

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A two-step process involving hydrophobic interaction chromatography and hydrophilic interaction chromatography was developed to purify chemically synthetic oxytocin out of economic and environmental consideration. First, Nylon 6 hydrophobic interaction chromatography was performed using water as mobile phase for desalting and enrichment. And Superose 12 hydrophilic interaction chromatography was performed for further purification. By this two-step purification process, the purity of oxytocin was increased up to 93.5% (5.96 folds purification) with final recovery rate of 50.1%, which was comparable with the results obtained from traditional two-step RPLC purification process with C18 medium. This two-step purification process consumed less organic solvent, which meant lower cost. Nylon 6 and Superose 12 media were chemically stable under extreme pH cleaning conditions and easily reproduced.

Microwave-assisted Drying of Danshen Slices and Dissolution of Lithospermic Acid B

GUO Yong-Xue XIU Zhi-long

. 2010, 10(3):  603-607. 

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Danshen slices were dried in a microwave oven to investigate the effects of microwave treatment on drying characteristics and quality of products in terms of drying time, drying rate, content of lithospermic acid B, and its dissolution rate in maceration at room temperature. The results showed that drying time decreased and drying rate increased with increasing microwave power. The best quality in term of lithospermic acid B content was observed in the drying period of 30 min with 650 W. The content and dissolution rate of lithospermic acid B were 1.20 times and 1.58 times higher than that of the sun light drying sample. The data were applied to calculate exponential equations. The performances of these models were compared according to the correlation coefficient (R2). The Page model was the best one to describe the microwave drying process. The experimental and theoretical results show that microwave drying technology could be used to produce dry Danshen slices with good quality in pharmaceutical industry.

Preparation of Macroporous Poly(styrene-glycidyl methacrylate) Microspheres with Controlled Pore Structure

LI Yan ZHOU Wei-qing; MA Guang-hui

. 2010, 10(3):  608-612. 

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Macroporous poly(styrene-glycidyl methacrylate) microspheres [P(ST-GMA)] were prepared using surfactant reverse micelle swelling method. The effects of GMA content, surfactant amount, diluents, and crosslinking agent amount on the pore distribution in microspheres were investigated. The results showed that the pore sizes of microspheres were remarkably increased with increasing of content of GMA. When the surfactant amount was added from 1.6 g to 2.0 g, the pore sizes were correspondingly increased from 100 to 720 nm. Further more, the pore sizes were positively related to the hydrophobicity of diluents. In addition, with the crosslinking agent amount was increased from 1.0 g to 2.0 g, the pore sizes were significantly decreased from 550 to 100 nm. Under the optimization conditions, macroporous P(ST-GMA) microspheres with special pore sizes and different contents of GMA were synthesized. The obtained macroporous microspheres can be used to link various ligands and applied as chromatographic media, or be directly used to immobilize enzymes.

材料工程专栏

Antibacterial Characteristics and Mechanism of Water-insoluble Polymeric Antimicrobial Material with Grafting Type

DU Rui-kui; LIU Qing GAO Bao-jiao

. 2010, 10(3):  613-618. 

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The grafting particulate CMPSt/SiO2 on which chloromethylated polystyrene was grafted on the surface of silica gel was used as a starting material, and the quaterisation and quaternary phosphine reactions were carried out using triethylamine, tributylamine and triphenyl phosphine as the reagents, resulting in two kinds of composite particles, QN-PSt/SiO2 and QP-PSt/SiO2. They are water-insoluble materials with high performance. Antimicrobial property of the two composite particles was mainly studied using Escherichia coli as a disease-leading bacterium and with the method of counting live bacterium plate. The relationship between their chemical structure and antibacterial property was examined. Their antibacterial mechanism was explored by measuring extracellular DNA and RNA. The experimental results show that two composiles possess high antibacterial activity, especially QP-PSt/SiO2, its antimicrobial rate can reach 100%. The density of antibacterial groups on the surface and chemical structure of antibacterial groups are the main factors affecting on the antibacterial property of the composite particles. The composite particles with high quaternary degree have stronger antibacterial ability. The antibacterial activity of QP-PSt/SiO2 with phosphine salt-type is much stronger than QN-PSt/SiO2 with quaternary ammonium salt-type. QN-PSt/SiO2 repared with tri-n-butylamine has stronger antibacterial ability than that prepared with triethylamine. The antimicrobial mechanism of QN-PSt/SiO2 and QP-PSt/SiO2 is based on a sterilizing bacterium process.

Preparation of Magnetophoresis Microcapsules and Displaying Properties of Their Coating Film

PEI Chun-lan; WU Hai-xia; DUAN Jun-ling; JIN Yong

. 2010, 10(3):  619-624. 

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Magnetophoresis microcapsules were prepared by using a complex coacervation with gelatin and arabic gum as film materials, and magnetic particles and TiO2 particles suspended in a mixture solution of di-n-butyl phthalate and C2Cl4 as inner medium. The prepared microcapsules with the sizes of 200~300 mm has transparent, smooth and elastic wall, which can be conserved for a long period. After coating and drying, the microcapsules form a flexible film which can be used for displaying and reuse in many times. The film can clearly display defects in standard samples with 100 mm width and 15 mm depth. The formation process of the microcapsules and the shape change presented were analyzed.