Volumn Content

The Chinese Journal of Process Engineering 2008 Vol.8 Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Preparation of Peracetic Acid from Acetic Acid and Hydrogen Peroxide: Experimentation and Modeling ZHAO Xue-bing;ZHANG Ting;ZHOU Yu-jie;LIU De-hua    2008, 8 (1): 0-0.   Abstract （2675）      PDF （197KB）（999）       Knowledge map    Save Based on the kinetic equations and equilibrium constants, some mathematic models were developed for calculating peracetic acid (PAA) concentration, equilibrium conversion rate of hydrogen peroxide, etc. The effects of several parameters on PAA synthesis were investigated by experimentation and modeling. The equilibrium constants determined from the forward and reverse rate constants at 293, 303, 313 and 323 K were 2.91, 2.81, 2.72 and 2.63, respectively. The models could predict the values of equilibrium concentration of PAA with average relative deviation of less than 10%. Both of the experimental and model-calculated results demonstrated that temperature and catalyst loading were the most important factors affecting the rate of PAA synthesis, but high temperature led to the decrease of equilibrium concentration of PAA. According to the model, the reaction could achieve equilibrium within 24 h when operated at 303 K with 1%~1.5%(w) sulfuric acid as catalyst. Additionally, when using anhydrous acetic acid and 30% hydrogen peroxide to prepare PAA, the volumetric ratio of the two solutions should be in the range of 1.2~1.5 in order to obtain the highest equilibrium concentration of PAA. This study can serve as a step towards the further optimization of PAA synthesis and some other related investigations. Related Articles | Metrics Select Dispersion Characteristics of Solid-Liquid Suspension in an Unbaffled Stirred Tank SHAN Xian-gen;YU Geng-zhi;YANG Chao;MAO Zai-sha;DU Ling-zhong;ZHANG Wei-gang    2008, 8 (1): 1-7.   Abstract （2139）      PDF （244KB）（810）       Knowledge map    Save The dispersion characteristics of water-silica two-phase system in an unbaffled stirred tank with diameter of 0.3 m, and height 0.45 m, equipped with a 0.15 m diameter 3-blade 70o PBTD (pitched blade turbine downflow) were studied. The profile of local solid concentrations was measured using a PC-6A fiber optic reflection probe. The effects of impeller speed from 113 to 173 r/min and impeller off-bottom clearance height from 0.08 to 0.16 m on particle concentration distribution were examined when the average particle phase holdup was set as 0.005(j). The results show that the suspension of solid particles in the stirred tank can be improved by increasing the impeller speed and decreasing impeller off-bottom clearance height. In the present experiment, solid particles reached the best suspension under the impeller speed of 173 r/min and impeller off-bottom clearance height of 0.08 m. Related Articles | Metrics Select Measurement of Particle Size Distribution in Fat Emulsion Using Ultrasonic Attenuation Spectrum DONG Li-li;SU Ming-xu;XUE Ming-hua;SHANG Zhi-tao;CAI Xiao-shu    2008, 8 (1): 8-12.   Abstract （2077）      PDF （231KB）（772）       Knowledge map    Save Characteristics of droplet particle size distribution (PSD) in concentrated fat emulsions were investigated using ultrasonic attenuation measurement. Based on theoretical analysis and numerical results, the experiments in ultrasonic spectrum with a bandwidth range of 2~13 MHz measurement were carried out for oil volume fraction from 1% to 20%. Combined with the inverse algorithm, fat droplet sizes and distributions were determined from experimental data. Comparison with the results of light extinction method indicated that ultrasonic spectra method could produce fairly consistent PSD results, in which particle sizes were below 1 mm. The error of experimental volume fraction and initial fraction (20%) is 3% and the deviation error between retrieval spectrum and experimental spectrum is smaller than 10%. Moreover, it is suitable for high concentration emulsion and non-destructive tests. Related Articles | Metrics Select Formation Behavior of Gas Bubbles with Laser Image Visualization Technique JIANG Shao-kun;FAN Wen-yuan;ZHU Chun-ying;MA You-guang;LI Huai-zhi    2008, 8 (1): 13-17.   Abstract （1932）      PDF （227KB）（708）       Knowledge map    Save Laser image visualization technique, combined with photographing method by charge coupling device, has been employed to study single bubble formation at a submerged orifice in glycerol aqueous solution. The photographs show that magnified two-dimensional bubble images have been obtained clearly. The effects of solution concentration, chamber volume, orifice diameter and gas volumetric flowrate on bubble volume are investigated experimentally. It is found that bubble volume increases with solution concentration and chamber volume, respectively, and decreases with the increase of orifice diameter in the range of 1, 1.5 and 2 mm. The effect of gas volumetric flowrate on bubble volume is related to orifice diameter. Bubble volume increases with gas volumetric flowrate when using the orifices with the diameters of 1 and 1.5 mm, respectively, but employing the orifice with the diameter of 2 mm, bubble volume decreases first, and then increases. Related Articles | Metrics Select Effect of Jet Gas on Solid Hold-up Profile in the Feed Injection Section of the Riser E Cheng-lin;FAN Yi-ping;LU Chun-xi;XU Chun-ming    2008, 8 (1): 18-22.   Abstract （1778）      PDF （190KB）（757）       Knowledge map    Save The effect of jet gas on the radial solid hold-up profile in the feedstock injection section of a FCC riser is investigated in a cold-model FCC riser. The experimental results demonstrate that three types of solid hold-up profiles can be used to describe the effect intensities of jet gas on solid flow in the feed injection zone of the riser. The three types have a distinct W-shaped distribution for very strong effect at the axial locations near the nozzle exits, an annular-core one for very weak effect in the axial positions further from the nozzle exits, and an indistinct W-shaped one for stronger effect between the two areas. Changes of solid hold-up from a W-shaped profile to an annular-core one indicate the lowered effect of jet gas on solid flow when increasing the jet gas velocity or decreasing the pre-lift gas velocity. Furthermore, the momentum ratio of jet gas to pre-lift two-phase mixture, Mj/Mr, is introduced to describe the effects of physical properties of gas and solid, operating conditions, and equipment configuration on solid hold-up distribution. With increasing Mj/Mr, the radial solid hold-up profile turns gradually from a W-shaped to an annular-core. The effects of operating conditions and equipment dimensions on solid flow are dependent on the momentum ratio. They are about 0.675~1.075 m when the momentum ratio is smaller than 4.21, and about 0.375~0.675 m when the momentum ratio is greater than 4.21. Related Articles | Metrics Select Relationships between Pressure Fluctuation and Flow Patterns in Standpipes of Circulating Fluidized Bed ZHANG Yi;PENG Yuan-yuan;WEI Yao-dong;SHI Ming-xian    2008, 8 (1): 23-27.   Abstract （3460）      PDF （541KB）（751）       Knowledge map    Save Pressure fluctuation in the f90 mm and f42 mm standpipes in a 15 m circulating fluidized bed was measured. The gas-solid two-phase flows under negative pressure gradient in the standpipes have low frequency pressure fluctuation, which can be described by standard deviation (Sd). Flow patterns in standpipes are classified as two types according to solids flux, dense conveying pattern and dilute-dense coexisting flow pattern. The pressure fluctuation intensity is great under the dense conveying pattern, which is mainly caused by intensive mutual action between solid and the gas entrained down. The pressure fluctuation intensity is relative weak under the dilute-dense coexisting flow pattern, which is caused by instabilities of solid discharge at the bottom dense part and weak gas-solid mutual action in the upper dilute part. With the solid flux increasing in the standpipes, pressure fluctuation is more intensive. For the dense conveying pattern, there exists nearly linear relationship between solid flux and pressure fluctuation intensity as Sd=0.00875Gs'-4.77 under the experimental condition of Gs'=550~850 kg/(m2×s). Related Articles | Metrics Select Pressure Leaching Kinetics of Marmatite XU Zhi-feng;QIU Ding-fan;WANG Hai-bei    2008, 8 (1): 28-34.   Abstract （2898）      PDF （211KB）（793）       Knowledge map    Save The pressure leaching kinetics of synthesized marmatite was studied. The effects of oxygen partial pressure in the range of 0.1~0.5 MPa and leaching temperature in the range of 388~418 K on leaching rates of zinc and iron were respectively investigated in the following conditions: initial concentration of H2SO4 as 0.77 mol/L, ratio of liquid to solid as 100 mL:10 g, and agitation speed as 550 r/min. The experimental results show that the leaching rate of zinc in 60 min at 388 K is increased from 35.69% to 89.80% when the oxygen partial pressure is raised from 0.1 to 0.5 MPa. The leaching rate of zinc in 30 min with the oxygen partial pressure of 0.3 MPa is increased from 44.00% to 85.93% when the leaching temperature is raised from 398 to 418 K. The experimental results also show that the linear relationship between the leaching rate of zinc and leaching time exits before the leaching equilibrium of zinc is achieved. The linear relationship between the leaching rate of iron and leaching time exits before iron is significantly precipitated by hydrolysis. The leaching rate constants of zinc and iron all increase with the increase of oxygen partial pressure and leaching temperature. The leaching rate constant of zinc is always higher than that of iron. The apparent activation energy is determined as 44.0 kJ/mol for the pressure leaching of marmatite. The leaching of zinc follows the shrinking core model with surface reaction control. The experimental result of the synthesized ore coincides with that of marmatite concentrate. Related Articles | Metrics Select Preparation of Hydroxyapatite with Industrial Gypsum and Its Adsorption upon Pb2+, Cu2+, Zn2+ and Ni2+ LIU Hai-di;LI Fu-zhi;ZHAO Xuan;CHEN Yun-fa    2008, 8 (1): 42-47.   Abstract （1700）      PDF （676KB）（752）       Knowledge map    Save The preparation method of hydroxyapatite (HAp) with industrial gypsum was investigated. The adsorption abilities of as-prepared samples upon Pb2+, Cu2+, Zn2+ and Ni2+ ions in aqueous solution were examined. It was indicated that pure HAp could be successfully fabricated when the molar ratio of (NH4)2HPO4 to industrial gypsum was 1:2 with the reaction between them for 24 h under 90℃. The as-synthesized HAp exhibited obvious adsorption ability upon Pb2+, Cu2+, Zn2+ and Ni2+ ions under pH 7, and their saturated adsorption amounts were 1095, 86.76, 64.68 and 67.90 mg/g respectively. Their adsorption behaviors could be described with the Langmuir model approximately. Related Articles | Metrics Select TAN Zhu-hong;ZHENG Shui-lin;LIU Yue    2008, 8 (1): 48-53.   Abstract （2785）      PDF （293KB）（727）       Knowledge map    Save Related Articles | Metrics Select Photocatalytic Degradation of Reactive Brilliant Blue X-BR with Al-doped ZnO Nano-particles SU Su;LU Shi-xiang;XU Wen-guo    2008, 8 (1): 54-59.   Abstract （2886）      PDF （578KB）（975）       Knowledge map    Save Pure ZnO and Al-doped ZnO particles were prepared using sol-gel method with zinc acetate dehydrate [Zn(CH3COO)2×2H2O], lithium hydroxide monohydrate (LiOH×H2O) and aluminum chloride (AlCl3×6H2O) as raw material. The samples were characterized by means of X-ray diffraction, infrared absorption spectroscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy and high resolution transmission electron microscope. The photocatalytic performance of different ZnO samples was studied using ultraviolet lamp as illumination device and reactive brilliant blue X-BR as stimulant pollutant. The effects of calcining temperature of precursor, photocatalytic temperature, irradiation time, concentration of pollutant, dark adsorption performance of the samples, amount of Al doping and content of catalyst on the degradation rate of reactive brilliant blue X-BR were investigated. The results indicated that when the calcining temperature was 300℃, the ZnO crystals crystallized well and the size of ZnO particles was small. Al doping to ZnO improved the photocatalytic performance of ZnO samples and the uniformity of the particles, but it did not improve the adsorption performance. Moreover, the Al-doped particles became much smaller evidently. In the doped samples (Al doping range 1%~7%), 5%Al-ZnO was the most active. When the reaction temperature was 30℃, the degradation rate of reactive brilliant blue X-BR could reach 95% by catalyst of 0.1 g/L in 45 min. Related Articles | Metrics Select Adsorption of Platinum by Novel Cross-linked Chitosan Resin Particles DANG Ming-yan;ZHANG Ting-an;WANG Ping;LI Wei;TAN Yan-kun;HE Yan    2008, 8 (1): 60-64.   Abstract （1705）      PDF （326KB）（732）       Knowledge map    Save Formaldehyde and chloromethyl thiirane were used to synthesize a novel cross-linked chitosan resin with adsorption ability to platinum. The structure of the resin was characterized by using SEM and XPS techniques, the effect of dosage of cross-linking agents on adsorption of platinum in Pt-containing solution was investigated, and adsorption kinetics, properties of isothermal adsorption and desorption were also studied. The results show that the optimum ratio of dosages for chitosan:formaldehyde:chloromethyl thiirane is 1 g:7 mL:2 mL. The adsorption kinetics follows Boyd liquid film diffusion model, liquid film diffusion is the control procedure, and apparent activation energy of adsorption is 14.28 kJ/mol. The isothermal adsorption follows the isothermal adsorption equations of Freundlich. Thiourea (1%)-hydrochloric acid (1 mol/L) was used to be desorption agent, and the desorption rate of adsorbed platinum could reach to 99.75% for 1 h. Related Articles | Metrics Select Photodegradation of Methylene Blue in a Batch Fixed Bed Photoreactor Using Activated Carbon Fibers Supported TiO2 Photocatalyst FU Ping-feng;ZHAO Zhuo;PENG Peng;DAI Xue-gang    2008, 8 (1): 65-71.   Abstract （1818）      PDF （224KB）（774）       Knowledge map    Save A batch fixed bed photoreactor, using felt-form activated carbon fibers (ACF) supported TiO2 photocatalyst (TiO2/ACF), was developed to carry out photocatalytic degradation of methylene blue (MB) solution. The effects of TiO2 particle size, loaded TiO2 amount, initial MB concentration, airflow rate and successive run on the decomposition rate were investigated. The results showed that photodegradation process followed a pseudo-first-order reaction kinetic law. The apparent first-order reaction constant kapp was larger than 0.047 min-1 with half reaction time t1/2 shorter than 15 min, which was comparable to reported data using suspended Degussa P-25 TiO2 particles. The high degradation rate was mainly attributed to adsorption of MB molecules onto the surface of TiO2/ACF. The photocatalytic efficiency still remained nearly 90% after 12 successive runs, showing that successive usage of the designed photoreactor was possible. The synergic enhancement effect in combination of adsorption with ACF and photodegradation with TiO2 was proved by comparing MB removal rates in the successive degradation and adsorption runs, respectively. Related Articles | Metrics Select Preparation of Aluminum Hydroxide with Dissolution of Sodium Aluminate in Methanol-Water Solvent WANG Xue;ZHENG Shi-li;ZHANG Yi    2008, 8 (1): 72-77.   Abstract （2124）      PDF （358KB）（818）       Knowledge map    Save Aluminum hydroxide was prepared by solventing-out method using methanol and water in the decomposition of sodium aluminate. The solubility of Al2O3 and Na2O in methanol-water solvent with different mass ratios of methanol was investigated at 30℃. In addition, the effects of mass ratio of methanol and reaction temperature on decomposition process of sodium aluminate hydrate were studied, and the obtained product was characterized by XRD, IR, SEM techniques, particle size distribution and purity analysis. The results showed that the solubility of Al2O3 and Na2O decreased with the increase of methanol mass ratio to solvent, its effect on solubility of Al2O3 was more remarkable, increasing the molar ratio of sodium aluminate significantly up to a peak value when the mass ratio of methanol was 0.8. The decomposition rate of sodium aluminate hydrate reached to 80%~90% in 1~3 h when the mass ratios of methanol to solvent were 0.5~0.8, while the rate would slightly decrease with the increase of temperature. The product was identified as bayerite with integrated IR peaks at 30℃, and it transformed to gibbsite when the temperature was higher. The prepared aluminum hydroxide consisted of pure and uniform tabular particulates with average 100 nm in thickness and 1 mm in diameter. Related Articles | Metrics Select Photocatalytic Degradation of Rhodamine B Using Semiconductors Photosensitized by Poly(fluorene-co-thiophene) under Visible Light Irradiation ZHANG Dong-dong;MO Yue-qi;SONG Lin;HUANG Xiong-fei;QIU Rong-liang    2008, 8 (1): 78-82.   Abstract （3074）      PDF （420KB）（714）       Knowledge map    Save The TiO2 and ZnO based photocatalysts prepared by poly(fluorene-co-thiophene) (PFT) modified TiO2 and ZnO have good photocatalytic activity under visible light. The results of Rhodamine B degradation showed that the photocatalytic activity of PFT/TiO2 was much better than that of PFT/ZnO. After 2 h irradiation under LED (light-emitting diode) lamp, Rhodamine B was completely degraded to colorless product, and the mineralization rate was 48% in PFT/TiO2 system. However, in PFT/ZnO system, there were lots of colored products left under the same condition, and the mineralization rate was only 24.6%. There were two steps involved in the degradation process of Rhodamine B. Firstly, the maximum absorbance peak became lower, and simultaneously there was a hypsochromic shift in the spectra. Secondly, Rhodamine B was decolored and degraded to produce Rhodamine. In the second step, Rhodamine was mineralized to CO2 and H2O continuously and the removal of TOC (total organic carbon) mainly took place in this step. Related Articles | Metrics Select Production of Acrylic Acid via Catalytic Partial Oxidation of Propylene in a Two-stage Fluidized Bed FENG Qi-yao;LUO Guo-hua;WEI Fei    2008, 8 (1): 83-87.   Abstract （3555）      PDF （186KB）（1233）       Knowledge map    Save The experimental results on production of acrylic acid from catalytic partial oxidation of propylene using a single-stage fluidized bed (SSFB) reactor and a two-stage fluidized bed (TSFB) reactor were presented. Experimental investigation for the first-step reaction was conducted on variation of propylene conversion rate and liquid product yield with operating parameters, such as temperature, propylene space velocity, and ratio of oxygen to propylene. The results indicate that the propylene conversion rate and liquid yield in the first-step reaction can be greatly improved up to 94.2% and 74.4% respectively in a two-stage fluidized bed reactor due to effectively suppressing gas backmixing and growth of bubbles in the catalyst bed. Meantime, this work also presented the optimal conditions of space velocity of propylene 20~21 L/(h·kg), operating temperature 360~365℃ and molar ratio range of oxygen to propylene 1.6~1.8 in the first-step process. Moreover, the propylene conversion rate and liquid yields in the first-step and two-step process in the acrylic acid production were also examined under the optimal operating conditions. Related Articles | Metrics Select Preparation of Micron Size Cuprous Oxide Powder from Acidic CuCl2 Etchant Waste Solution HUANG Ling-yun;ZHU Guo-cai;CHI Ru-an;ZHAO Yu-na    2008, 8 (1): 88-92.   Abstract （1793）      PDF （376KB）（633）       Knowledge map    Save A micron size Cu2O powder was prepared by glucose reduction method from acidic cupric chloride etchant waste solution. The optimal conditions were determined as follows: the molar ratio of glucose to copper ion in waste is 0.8, pH 8~9, reaction time 1 h, and reaction temperature 80℃. The purity of the powder product can reach to 99.34%, and the copper recovery rate from etching waste is 99.7%. XRD analysis indicates that the peak of impurity is not found, and the product is not oxidized after 50 d. The size distribution of Cu2O powder ranges from 1.8 to 2.2 mm. The result of TG study further verifies that Cu2O is not oxidized below 250℃. The morphology of Cu2O particles is characterized by SEM, showing that the particles have polyhedral structure. Such Cu2O powder can be a promising material used widely in the fields of catalyst, coating, painting and coloring agents. Related Articles | Metrics Select Effect of Al-containing Precursors on Ionothermal Synthesis of Aluminophosphate Molecular Sieve WANG Shao-jun;HOU Lei;XU Yun-peng;TIAN Zhi-jian;YU Jia-you;LIN Li-Wu    2008, 8 (1): 93-96.   Abstract （3314）      PDF （372KB）（681）       Knowledge map    Save Aluminophosphate molecular sieve AlPO4-11 was synthesized in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bromide as both the solvent and template with different Al sources at ambient pressure. The effects of composition of incipient gels, crystallization time and crystallization temperature on synthesis of AlPO4-11 molecular sieve with different Al sources were investigated. The structure of AlPO4-11 molecular sieve was characterized by X-ray diffraction and scanning electron microscopy. The results indicated that the different properties of raw materials lead to the different mechanisms and rules on the ionothermal synthesis. When Al[OCH(CH3)2]3 was used as the Al source, the optimal ratio of P/Al in the incipient gels was 3/1, the crystallization was slow. When Al2O(CH3COO)4·4H2O was used as the Al source, the ratio of P/Al in the incipient gels was low (P/Al=1.5/1) and the crystallization was rapid. Related Articles | Metrics Select Vapor-Liquid Equilibria in Binary Systems of Methacrolein and Methanol with [BMIM]BF4 CHEN Qiong;YAN Rui-yi;YUAN Xiao-liang;ZHANG Suo-jiang    2008, 8 (1): 97-101.   Abstract （2037）      PDF （197KB）（796）       Knowledge map    Save Vapor-liquid equilibria in the binary systems of methacrolein and methanol with 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) were determined at 350.75, 341.55 and 331.55 K in this work. The non-random tow-liquid equation was applied to correlate the experimental data. The results showed that the solubility of methacrolein in [BMIM]BF4 decreased with temperature increasing and increased with pressure increasing, and the solubility of methanol in [BMIM]BF4 had the similar phenomenon. Compared with ideal solution, the system of methacrolein with [BMIM]BF4 showed positive deviation, and the system of methanol with [BMIM]BF4 showed negative deviation. The correlated results with non-random tow-liquid model were in good agreement with the experimental data. The average relative deviation of methacrolein and [BMIM]BF4 system was 1.20%, and that of methanol and [BMIM]BF4 system 0.42%. Related Articles | Metrics Select Simultaneous synthesis of 1,3-dihydroxyacetone (DHA) and 2-aminobutyric acid from glycerol and 2-oxobutyric acid was achieved by coupling the reactions of two enzymes, glycerol dehydrogenase and leucine dehydrogenase with in situ regeneration of coenzyme. MIAO Wei-juan;WANG Ping;ZHANG Song-ping    2008, 8 (1): 102-108.   Abstract （1946）      PDF （269KB）（817）       Knowledge map    Save Simultaneous synthesis of 1,3-dihydroxyacetone (DHA) and 2-aminobutyric acid from glycerol and 2-oxobutyric acid was achieved by coupling the reactions of two enzymes, glycerol dehydrogenase and leucine dehydrogenase with in situ regeneration of coenzyme. The effects of concentrations of substrates and coenzyme NAD+ on the yields of the products and the total turnover number (TTN) of the multi-enzyme reaction system were examined. The results show that the TTN value could reach 5110 with an initial NAD+ concentration of 0.1 mmol/L. The observed yields of products were 1.4% and 2.6% for glycerol and 2-oxobutyric acid respectively, based on the amount of substrates used. The strong inhibitory effects of DHA and 2-aminobutyric acid on GDH and LDH were regarded as the main causes for such low product yields. Accordingly, an effective removal strategy of products will be necessary for future improvement of the efficiency of the reaction system. Related Articles | Metrics Select Application of Exponential Fed-batch Model for Reducing Repression during g-CGTase Production by Bacillus macorous WANG Feng;DU Guo-cheng;GU Zheng-biao;CHEN Jian    2008, 8 (1): 109-114.   Abstract （1876）      PDF （302KB）（707）       Knowledge map    Save The Influences of agitation speed, temperature and pH-controlling strategy on cell growth, linear maltooligosaccharides accumulation in broth and g-CGTase yield were investigated in the batch culture of Bacillus macorous. When the maximal value of specific growth rate was higher than 0.2 h-1, the g-CGTase yield decreased. The linear maltooligosaccharides generated during fermentation can promote the cell growth and elevate the intracellular contents of FDP, ATP and G6P, which demonstrated a repression effect on the production of g-CGTase. Hence, the exponential feeding mode of nutrients was carried out to control the catabolite repression by limiting the specific cell growth rate. The highest yield of g-CGTase obtained in fed-batch was 2565 U/mL, which was 7.9 times of that in batch fermentation. Related Articles | Metrics Select Effects of Ultrasonic Wave on Cell Growth and Shikonin Biosynthesis in Suspension Culture of Arnebia euchroma GE Feng;CHEN Chao-yin;WANG Xiao-dong;ZHAO Bing;WANG Yu-chun    2008, 8 (1): 115-119.   Abstract （2942）      PDF （356KB）（693）       Knowledge map    Save The effects of ultrasonic wave power and treatment time on the cell growth and shikonin biosynthesis of Arnebia euchroma were investigated. The results showed that the stimulation of ultrasonic wave promoted A. euchroma cell growth in suspension culture. Low power density and long time treatment or high power density and short time treatment by ultrasonic wave was favorable to the cell growth. The cell biomass productivity was 61% higher than that in control by the end of the culture period under the optimal conditions of 200 W ultrasonic wave treatment for 1 min. The shikonin content and shikonin production in suspension culture of A. euchroma cells were enhanced by ultrasonic stimulation as well. When the ultrasonic stimulation was carried out after inoculation, the ultrasonic power density was 39.9 mW/cm3 and the stimulation time was 3 min, the shikonin content and shikonin production gained the highest results (2.72%, 294 mg/L), which were 64% and 135% higher than those obtained in control, respectively. The strengthening of shikonin biosynthesis may be due to increasing the activity of phenylalanine ammonia lyase caused by ultrasonic stimulation. Related Articles | Metrics Select Co-production of Nattokinase and g-Poly Glutamic Acid by Bacillus subtilis Natto NLSSe QIN Guo-hong;xiong-xiao-chao;ZHANG Ju-hua;XING Jian-min;LIU Hui-zhou    2008, 8 (1): 120-124.   Abstract （1820）      PDF （222KB）（731）       Knowledge map    Save The synthesis of g-poly glutamic acid (g-PGA) by the strain Bacillus subtilis Natto NLSSe which can be used to synthesize nattokinase was investigated. g-PGA was synthesized in the medium without the addition of L-glutamic acid, showing that the strain was a L-glutamic acid-independent bacterium. The molecular weight of the g-PGA was about 2~3 million Dalton. The suitable carbon and nitrogen sources for the synthesis of nattokinase were sucrose and soya peptone respectively. The suitable carbon and nitrogen sources for the synthesis of g-PGA were citric acid and NH4Cl respectively. The results of orthogonal experiments showed that increasing the concentrations of soya peptone and citric acid could enhance the synthesis of nattokinase and g-PGA respectively, in the meantime the synthesis did not result in restraint formation between the two products. This merit was beneficial to the co-production. The yields of both products could achieve the levels of the single synthesis when the concentrations of soya peptone, NH4Cl and citric acid were 10, 9, 15 g/L respectively, the activity of nattokinase reached 121.2 U/mL, and the concentration of g-PGA reached 1.1 g/L. Related Articles | Metrics Select Study on Specific Desulfurization Activity and Related Genes of Rhodococcus sp. LY822 BAI Xue-jing;xiong-xiao-chao;JIANG Sheng-hua;LIU Hui-zhou;LI Xin    2008, 8 (1): 125-129.   Abstract （1743）      PDF （328KB）（707）       Knowledge map    Save Desulfurization related genes of a dibenzothiophene desulfurizing bacterium Rhodococcus sp. LY822 were separately amplified via polymerase chain reaction with specific primers based on the related sequences of Rhodococcus erythropolis IGTS8, and dszA, dszB and dszC were cloned. Three expression plasmids, pETA, pETB and pETC, were constructed and transformed into E. coli BL21 strain. After the isopropyl-beta-d-thiogalactopyranoside induction with them, dszA, dszB and dszC were expressed effectively in the recombinant E. coli BL21 strain. The SDS-PAGE results indicated that the molecular weights of desulfurization related genes expression products were about 50, 40 and 45 kDa. Desulfurization activity analysis showed that BL21(DE3)(pETC) cell-free extracts could convert 0.02 mmol/L DBT into DBTO2. BL21(DE3)(pETA) cell-free extracts could convert 0.01 mmol/L DBTO2 into HBPS. BL21(DE3)(pETA) and BL21(DE3)(pETB) cell-free extracts could convert 0.01 mmol/L DBTO2 into 2-HBP. It could be concluded that Rhodococcus sp. LY822 could specially break the C?S bond of dibenzothiophene and convert dibenzothiophene into 2-hydrobenzophene by "4S" biodesulfurization pathway. Related Articles | Metrics Select Preparation of Uniform Size Chitosan Microspheres by a T-shaped Microchannel Device HU Xue;WEI Wei;LEI Jian-du;MA Guang-hui;SU Zhi-guo;WANG Hua-jun    2008, 8 (1): 130-134.   Abstract （2879）      PDF （354KB）（774）       Knowledge map    Save Uniform size chitosan microspheres were prepared by a novel T-shaped microchannel. The effects of emulsifier, different flow rate ratios and flow rates on the preparation of chitosan microspheres were studied, respectively. In addition, chitosan droplets with different molecular weights were prepared using the T-shaped microchannel device, and the effects of different glutaraldehyde solutions on cross-linking of microspheres were studied. The preparation conditions of chitosan microspheres were determined as follows: the diameter of oil phase channel in the T-shaped microchannel was 350 mm, the diameter of water phase channel was 65 mm, and the joint diameter of two channel was 16 μm. 1.5%(w) chitosan was dissolved in aqueous acetic acid, which was used as a water phase. A mixture of liquid paraffin and petroleum ether 7:5(j) containing 4%(w) PO-500 emulsifier was used as an oil phase, the flow rate of water phase was 20 mL/min, and the flow rate ratio of oil to water phase was 15:1. The results show that the coefficient of variation (CV value) of all the chitosan droplets was below 10%. Glutaraldehyde toluene solution was finally chosen as the cross-linking agent of microspheres, the molar ratio of aldehyde group of glutaraldehyde to amino group of chitosan at 1:1 and the cross-linking time of glutaraldehyde 2 h. Related Articles | Metrics Select Site-directed Mutagenesis of Putative Adenylylation Site of Glutamine Synthetase and Glutamine Production HUANG Xing;ZENG Xing;LIU Ming;GONG Bo;HU Miao;CAO Zhu-an    2008, 8 (1): 135-139.   Abstract （1818）      PDF （314KB）（713）       Knowledge map    Save To avoid deactivation of glutamine synthetase (GS) resulting from adenylylation, site-directed mutagenesis was used to replace Tyr405, the putative adenylylation site of GS in Corynebacterium glutamicum, by Phe405. The mutant gene was expressed in E. coli to obtain GS which can enhance the enzymatic conversion from glutamate to glutamine. The wild gene with Tyr405 and the mutant gene with Phe405 were constructed into the recombinant E. coli pET-3a/GSI and pET-3a/GSIM, respectively. GS activity expressed in pET-3a/GSIM is 150 U/L which is 5.0 times as 30 U/L in pET-3a/GSI. Glutamine productivity in pET-3a/GSIM is 17.5 g/L which is 5.1 times as 3.4 g/L in pET-3a/GSI. Related Articles | Metrics Select Over-expression of GL-7-ACA Acylase Gene in E. coli LIN Chen-lu;LI Qiang;LIU Ya-fei;WANG Bo    2008, 8 (1): 140-143.   Abstract （1867）      PDF （285KB）（647）       Knowledge map    Save The constitutive expression of glutaryl-7-amidocephalosporanic acid (GL-7-ACA) acylase was realized. Based on it, a new plasmid pGEMKT-HPfACY with optimized RBS was constructed and transformed into E. coli JM105. After culturing in LB media, this recombinant strain reached an activity of 0.44 U/mL. This activity was twice of former one while the activity of the strain JM105/pGEMKT-HPRfACY reached as high as 2.98 U/mL using corn-steep as culture media. The acylase activity of recombinant strain hit 6.37 U/mL, using a strategy of controlling pH 7.5 by adding nutrient such as glycerin. Related Articles | Metrics Select Two-stage Temperature Controlling Strategy for Kefiran Production in the Culture by Lactobacillus kefiranofaciens ZHU Zhi;LIAO Xian-yan;JI Kai;DU Guo-cheng;CHEN Jian    2008, 8 (1): 144-147.   Abstract （1717）      PDF （198KB）（700）       Knowledge map    Save In batch culture for Kefiran production with Lactobacillus kefiranofaciens, the maximal values of average specific growth rate and average specific production rate of Kefiran were obtained at a higher temperature (33℃) in the first culture stage, afterwards, their maximums were obtained at a lower temperature (28℃). A two-stage temperature controlling strategy was proposed to enhance both the yield and the productivity of Kefiran. As a result, Kefiran concentration reached 4.65 g/L, which was respectively increased by 12% and 46% of that at 28 and 33℃, and Kefiran productivity was increased by 36% and 33% of that at the above two temperatures respectively. Related Articles | Metrics Select Analysis of the Composition in the Enzymic Synthesis of Amoxicillin by High Performance Capillary Electrophoresis LIU Yang-qiu;LI Qiang;WANG Ya-hui;YANG Ji-chu    2008, 8 (1): 148-151.   Abstract （1930）      PDF （194KB）（716）       Knowledge map    Save A analysis method for the determination of amoxicillin (Amox), D-p-hydroxyphenylglycine methyl ester (D-HPGM), D-p-hydroxyphenylglycine (D-HPG), 6-aminopenicillanic acid (6-APA) and phenylacetamide (PAA) in the reaction of enzymic synthesis of amoxicillin by high performance capillary electrophoresis was established. The optimal separation was carried out at 25℃, 25 kV, injection pressure 3.45 kPa, inject time 5 s, and detection wavelength 214 nm, using 0.1% benzoic acid as internal standard and 50 mmol/L borate (pH 9.0) buffer with 6 mg/mL PEG4000. For D-HPGM, D-HPG, Amox, 6-APA and PAA, there is a good linear relationship between the ratio of peak areas and the concentration in the ranges of 0.1~0.6, 0.1~0.16, 0.1~1.0, 0.1~2.0 and 0.1~2.0 mg/L respectively. The average recovery rates of the above five analytes are 101.45% (RSD=1.33%), 97.5% (RSD=1.69%), 101.5% (RSD=2.44%), 99.9% (RSD=1.27%) and 101.3% (RSD=0.35%) respectively. The results show that the HPCE method is convenient, economical, sensitive and satisfactory in determination of the analytes in enzyme-based production of amoxicillin. Related Articles | Metrics Select Preparation of Multilayer Dextran Sulfate/Protamine Capsules Templated on ZnO Microspheres and Their Drug Controlled Release Behavior YANG Xiao-ling;QIAO Qin-yu;CAO Hui-min;ZHU Yi-hua    2008, 8 (1): 152-156.   Abstract （1532）      PDF （404KB）（634）       Knowledge map    Save Ultrathin polyelectrolyte capsules were produced by layer-by-layer assembling of biodegradable polyelectrolytes, dextran sulfate (DXS) and protamine (PRM), on ZnO microspheres followed by the cores decomposition with dilute HAC solution. ZnO microspheres were well mono-dispersed and had around 5 nm intermediate size pores, which could be used as fluorescein delivery. PRM and DXS formed regular growing stable multilayers on ZnO microspheres, thus formed ZnO/(DXS/PRM)8 core-shell microspheres. After removal of ZnO template, (DXS/PRM)8 capsules were fabricated. The loaded drug amount and controlled release behavior of hollow capsules were examined in the sample of dexorubicin hydrochloride (DOX). The result shows that (DXS/PRM)8 demonstates obvious controlled release of DOX drug. Related Articles | Metrics Select Influential Factors in Formation of Rod-like Nickel Dimethylglyoximate Particles LIN Hang;WANG Bing-xi;WEI Zhong-jun    2008, 8 (1): 157-161.   Abstract （2757）      PDF （477KB）（725）       Knowledge map    Save Rod-like nickel dimethylglyoximate [Ni(dmg)2] particles were prepared from aqueous solution in this work. The prepared samples were characterized by XRD and UV-Vis absorption spectrometry, and their morphology was observed by optical microscope and SEM. The influential factors including pH, temperature, ultrasonification and surfactant were investigated. The experimental results show that the diameters and lengths of Ni(dmg)2 rods decrease obviously with increasing pH from 5.0 to 9.0, but slightly increase at the pH value of 10.5. With the rise of temperature, the diameter of Ni(dmg)2 becomes wider and the length longer. Ultrasonification makes both diameter and length of Ni(dmg)2 decrease markedly. The dimensions of particles become more unifrom when surfactants are added. Ionic surfactants have little influence on the size of Ni(dmg)2 rod, while neutral polyethylene glycol (PEG-1000) leads to the rod length longer. By controlling appropriate preparation conditions, the dimensions of rod-like Ni(dmg)2 can be adjusted from the scale of nanometer to micrometer. Related Articles | Metrics Select Assembling Magnetic Iron Nanoparticles in Mesoporous Silica Spheres with Expanded Pore Size WANG Ping;ZHU Yi-hua;YANG Xiao-ling;HAN Xiao    2008, 8 (1): 162-166.   Abstract （1825）      PDF （405KB）（771）       Knowledge map    Save Mesoporous silica (MS) microspheres with about 3 nm pore size were synthesized by n-hexadecylamine and TEOS in definite experimental conditions. To facilitate the incorporation of magnetic nanoparticles, an approach for three-ingredient salt impregnating was proposed for expanding the pore size of spheres with large extent. MS spheres were impregnated into three-ingredient salt of NaCl: LiCl:KNO3=20:5:5 (mass ratio) at 300℃ for 2 h to enlarge the pore size of MS spheres. The average pore size of modified MS spheres was about 10 nm. The magnetic nanoparticles within the pores of modified MS microspheres were synthesized by electrochemical method. Finally, the obtained iron-functionalized silica microspheres were thermally reduced under the hydrogen atmosphere to produce iron/silica magnetic composite. The result showed that Fe nanoparticles were incorporated into the pores of MS spheres. Related Articles | Metrics Select Preparation and Photocatalytic Activity of Co-doped TiO2 Nano-particles SONG Lin-yun;WU Yu-cheng;LIU Xiao-lu;LU Xiang-fen    2008, 8 (1): 167-171.   Abstract （1528）      PDF （270KB）（694）       Knowledge map    Save Co-doped nanometer TiO2 photocatalyst was prepared by sol-gel method with Ti(OBu)4 as precursor and HAC as complexation reagent. The composition and microstructure of prepared Co-TiO2 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherm. The structure of the nanocomposite and the relationship between the concentration of Co and its photocatalytic activity were also studied. The optimum molar ratio of Co/Ti and heat treatment temperature were obtained. The results showed that with doping of Co, anatase-TiO2 became more stable and the phase transformation from anatase to rutile was blocked. The particle sizes of Co-TiO2 were in the range of 10~20 nm. The optimal heat treatment temperature of Co-TiO2 powder was 500℃ and molar ratio of Co/Ti 0.1. Under these conditions photocatalytic decomposition rate of methyl orange solution reached the highest, up to 85% under 3 h irradiation with ultraviolet light. Related Articles | Metrics Select Preparation of N-doped TiO2 Photocatalyst and Analysis of Doping Process TANG Jian-jun;WANG Yue-jun;XIE Wei-ping;ZOU Yuan;ZHOU Kang-gen    2008, 8 (1): 172-176.   Abstract （2733）      PDF （363KB）（733）       Knowledge map    Save N-doped TiO2 photocatalyst was prepared by calcination of hydrated titanium dioxide using saturated urea solution as precipitant in air atmosphere. The obtained yellow samples were characterized by XRD, BET and UV-Vis techniques, and the results indicated that their grain sizes were 10~30 nm, and specific surface areas 30~70 m2/g, which could absorb visible light wavelength above 400 nm. Photocatalysis results with N-doped TiO2 as photocatalyst showed that over 40% of 2,4-dicholophenol could be degraded after 3 h reaction when using a fluorescent lamp with the main wavelength of 420 nm as the light source. The nitrogen doping process was analysed with TG-DTA, FT-IR and XPS techniques, the results indicated that nitrogen element distributed uniformly in the precursor, and nitrogen was doped into TiO2 lattice in the form of Ti?N bond when the crystalline structure of TiO2 was changed from amorphous to anatase phase. Related Articles | Metrics Select Synthesis and Characterization of Hollow Mn-Fe Oxide Magnetic Microspheres ZHANG Xiao-jun;CHEN Jian-ding;XUAN Shao-feng;MA Xin-sheng;HUANG Guang-jian    2008, 8 (1): 177-181.   Abstract （1554）      PDF （316KB）（761）       Knowledge map    Save The magnetic microspheres with polystyrene (PS) spheres as cores and Mn-Fe oxide as shells were synthesized by deposition and surface reaction. The effect of different ratios of manganese salt on magnetic product was studied. To obtain the hollow magnetic microspheres, the PS core in spheres was removed by calcination and extraction in solvent, respectively. The relation of calcination temperature to the spheres specific surface area was investigated. The removal efficiency of PS via extraction was also examined. In comparison of the calcination and extraction in solvent, it is shown that the hollow Mn-Fe oxide microspheres obtained from the former way are better than those from the latter one. The optimal conditions to form hollow Mn-Fe oxide microspheres by calcination were explored, the results show that the saturation magnetization and specific surface area of the hollow Mn-Fe oxide microspheres were measured as 68.66 emu/g and 27.8438 m2/g respectively when calcinated at 400℃. Related Articles | Metrics Select Flame Retardancy of Epoxy Resin Doped with Pentaerythritol Diphosphonate GAO Ming;LI Gui-fen;YANG Rong-jie    2008, 8 (1): 182-186.   Abstract （1733）      PDF （216KB）（787）       Knowledge map    Save Pentaerythritol diphosphonate melamine-urea-formaldehyde resin salt, a novel cheap macromolecular intumescent flame retardants (IFR), was synthesized, and its structure was a caged bicyclic macromolecule containing phosphorus characterized by FT-IR, which was applied to epoxy resin (EP). The thermal behavior and flame retardancy of samples were determined by TG-DTG and cone calorimeter (CONE). Activation energy for the decomposition of samples was obtained using the Broido equation. The resultant data show that for the flame retardant doped EP, average value of heat release rate is decreased by 30.7%, total heat release decreased by 52.2%, smoke and gas release decreased by 42.7%, CO release decreased by 70.5%, CO2 release decreased by 73.5%, and char yield is increased by 19.1%. 30% weight of IFR is doped into EP to get 30.5 of the limiting oxygen index, whose flame retardancy is similar to DOPO. The activation energy for the decomposition of EP is 73.5 kJ/mol while it becomes 83.5 kJ/mol when IFR is doped into, decreased by 10 kJ/mol, which shows that IFR can catalyze decomposition and carbonization of EP. Related Articles | Metrics Select Synthesis of Silicalite-1 Zeolite Membrane with Vacuum Seeding Method and Its Characterization of Performance WANG Ai-fang;SUN Wei-guo;KONG Chun-long;ZHAO Qing-yu;YANG Jian-hua;WANG Jin-qu    2008, 8 (1): 187-191.   Abstract （1568）      PDF （655KB）（728）       Knowledge map    Save Silicalite-1 zeolite membrane was successfully synthesized on tubular a-Al2O3 support by secondary synthesis with vacuum seeding. The as-prepared seed and membrane were characterized by XRD, SEM, TEM and single-gas permeability measurement. The results indicate that the prepared membrane was a typical Silicalite-1, a continuous and uniform seeding layer was attached to the a-Al2O3 support, the sizes of the Silicalite-1 molecular sieve were 0.2, 0.5, 1 and 2 mm with uniform distribution, and the prepared membrane was dense, regrown and crack-free. The influencial factors of vacuum and seed size were also investigated. At ro Related Articles | Metrics Select Preparation of Cordierite-supported Solid Acid Catalyst for Esterification ZHANG Qi;WANG Tie-jun;WU Chuang-zhi;MA Long-long    2008, 8 (1): 192-196.   Abstract （1693）      PDF （244KB）（677）       Knowledge map    Save Cordierite was taken as carrier to support activated solid acid in order to find out the optimum technical process to prepare cordierite-supported solid acid catalyst and guarantee the high esterification activity according to the model reaction of acidic acid and ethanol to ethyl acetate. The suspending solution of solid acid fine particles was homogeneous and steady, but g-Al2O3 or PEG addition deactivated the modified catalyst. The suspending solution with activated components and 1 mol/L H2SO4 of 50% volume ratio was proved to be best impregnation medium. The solid acid was testified as activated center on the cordierite surface, which showed best activity with acetic acid conversion rate of 79.2%, and 95.6% of that in the 2nd run in 100 min total reflux esterification of ethanol and acetic acid. The preparation process was repeatable and reliable, and can guarantee the modified cordierite catalyst with the suitable dimensions, uniform tunnels, and high esterification activity and economically availible as well. Related Articles | Metrics Select Fabrication of Reaction-bonded Si3N4-BN Composite YUAN Lei;YU Jing-kun    2008, 8 (1): 197-201.   Abstract （1591）      PDF （477KB）（601）       Knowledge map    Save Si3N4-BN composite was prepared by using Si and BN as raw materials under nitrogen gas flow at 1450℃ by the reaction-sintering method. The phase compositions under different sintering schedules and BN contents were examined with X-ray diffraction analysis. The fracture surface of the composite was investigated by SEM. Apparent porosity, bulk density and bending strength were also measured. And the sintering mechanism under Fe2O3 addition and the formation mechanism of b-Si3N4 were discussed. The results showed that only Si3N4 and BN phases existed in the composite when the sintering schedule was 1450℃ and 45 h. With increasing of BN content, relative density and bending strength decreased and the b-Si3N4 phase increased. When the BN content was 30%, the relative density, bending strength and b-Si3N4/a-Si3N4 phase ratio were 73.3%, 52.5 MPa and 3.4, respectively. Related Articles | Metrics Select Characteristics and Formation Mechanism of Secondary Organic Aerosol BAI Zhi-peng;LI Wei-fang    2008, 8 (1): 202-208.   Abstract （4008）      PDF （237KB）（1540）       Knowledge map    Save The formation of secondary organic aerosol (SOA) is one of the research focuses in atmospheric chemical process. In urban atmosphere, secondary organic carbon constitutes about 17%~65% of the total particulate organic carbon. Monoterpene and aromatics are the most important natural and anthropogenic precursors of SOA, respectively. The volatile precursors react with atmospheric oxidants such as hydroxyl (×OH), nitrate radical (NO3-) and O3 through multiple reaction pathways, producing semi-volatile secondary organics including diacids, multifunctional carbonyls and nitrate organics, etc. Theses compounds can distribute into particulate phase via adsorption and absorption processes, and will alter the property and environmental effects of ambient aerosols. Organic molecular markers are utilized to apportion the sources of atmospheric ambient aerosols, and organic diacids are potential tracers for SOA. In this article, the advances and problems in SOA research are reviewed, and future research recommendations are presented. Related Articles | Metrics Select Gas Holdup in a Bubble Column at Elevated Temperature with Organic Liquid Solutions HUANG Juan DAI Gan-ce    2008, 8 (2): 209-216.   Abstract （2580）      PDF （304KB）（887）       Knowledge map    Save Gas holdup (eg) was studied in a bubble column operated at elevated temperature. The column is 300 mm in diameter and 1.2 m in height, and the distributor has four nozzles with large diameter. The adjusted mixture of acetic acid (the solvent of the reaction) and p-, m-, o-xylene (homologous compound mixture of the reactant) was employed as the liquid phase, considering the oxidation of p-xylene. The experiments were conducted systematically to investigate the influences of superficial gas velocity (Ug), temperature, composition of the organic solutions on eg. The research ranges of superficial gas velocity and temperature were 0.009~0.224 m/s and 11~99℃ respectively. The effect of superficial gas velocity was summed up by eg-Ugn, the value of n varied with temperature, that is, n=0.6 at ambient temperature, n=0.4~0.5 at elevated temperature and 0.2 at the nearing boiling point. There was a transition point at eg-T curve, so the effect of temperature on eg can be classified into two stages, one far from the boiling point and another near to the boiling point. eg was nearly a constant at the first stage and increased significantly at the second. The critical temperature was varied with the superficial gas velocity, it was 90℃ in the range of 0.009~0.045 m/s and 70℃ from 0.072 to 0.18 m/s. As to the effect of the composition of organic liquid solutions, eg increased at first, and decreased when the mass concentration of acetic acid was higher than 80% in tap water-acetic acid system, eg in the acetic acid-xylene solution was lower than that of the water-acetic acid, while solutions had the same acetic acid content, eg in partly soluble water-acetic acid-xylene system was lower than that of the completely soluble system. A gas holdup correlation implicating the effects of various factors was given. Related Articles | Metrics page Page 1 of 6 Total 223 records First page Prev page Next page Last page