Table of Content

20 October 2002, Volume 2 Issue 5

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5

Experimental Observation on Cellulosic Biodegradation in Solid State Fermentation

ZHOU Xiao-hong; CHEN Hong-zhang; LI Zuo-huo

. 2002, 2(5):  0-0. 

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A mixed medium of steam exploded wheat straw (SEWS) and wheat bran was fermented in solid state by Penicillium decumbens JUA10. Various degraded constituents and activities of enzymes were analyzed. The process of biodegradation of cellulose is actually simultaneous saccharification and fermentation, and feedback inhibition of reducing sugar on cellulose or hemicelluloses may not heavily occur. Biodegradation of cellulose, hemicellulose was not proportional to activities of cellulase and hemicellulase. The compact structure of lignocellulose was the major cause for the low degradation rate of cellulose and hemicellulose. Hemicellulose was degraded even more slowly than cellulose. Starch was degraded easily while lignin was not degraded.

Review on Facilitated Transport in Fixed Site Carrier Membranes

SHI Wei; ZHANG Feng-bao; ZHANG Guo-liang; ZHANG Gang

. 2002, 2(5):  0-0. 

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Facilitated transport membrane with fixed site carriers is an attractive topic in the separation of gas and liquid mixtures because it is capable of increasing permeability and permselectivity simultaneously. In this paper, the mechanism of facilitated transport in fixed carrier membranes is addressed, the methods of carriers fixation are discussed and the problems to the development of the membrane process are summarized. In addition, the prospect of facilitated transport in fixed carrier membranes is previewed.

Kinetics of Reduction of Sodium Chlorate with Sulfur to Produce Chlorine Dioxide

PENG Qing-jing; FU Wei-chang; PENG Liang-bin

. 2002, 2(5):  0-0. 

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The kinetics of sodium chlorate reduction with sulfur to produce chlorine dioxide was investigated. It was shown that the selectivity of sulfur oxidized to sulfuric acid was 100%, the selectivity of chlorate ion to chlorine dioxide was over 98%. The kinetic equation is rC = k CACB, the apparent activation energy is 61.4 kJ/mol, and the reaction rate constant k=1.36′107 exp(–7380/T) [L2/(m2.min.mol)].

Simulation on the Conductivity of Charging Stock with Percolation Structure in the Submerged Arc Furnace

CHU Shao-jun(储少军);NIU Qiang(牛强);LIU Xin-yu(刘新宇);WANG Xin(王欣)

. 2002, 2(5):  0-0. 

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Thiobacillus ferrooxidans oxidating ferrous sulphate effectively at low pH (pH<2.0) is prerequisite to the industrial application of two-step bioleaching. In this work, the strain was adapted by sequential adaptive culture and isolation via continuous culture. Compared with the original Thiobacillus ferrooxidans TF5, its optimum pH for oxidating ferrous iron was changed from 2.0~3.0 to 1.7~2.0, and the ratio of oxidized ferrous iron was improved from 13.1% to 85% at pH=1.7. Kinetic research showed that, under the optimized cultural condition of initial pH=1.7, culture temperature near 31oC, 98% of ferrous iron contained in 9K medium was oxidized after cultivation for 52 h in a 250 ml Erlenmeyer flask incubated on a rotary shaker at 120 r/min, and the growth rate of Thiobacillus ferrooxidans cells was 0.0635 h-1, which is similar to the original type. It was showed that the adapted Thiobacillus ferrooxidans is potentially useful in the industrial application of two-step bioleaching.

Preparation of Mesopore Activated Carbon from Municipal Solid Organic Wastes

XIE Li-ping; LIN Wei-gang; YANG Xue-min

. 2002, 2(5):  0-0. 

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In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through steam reforming reactions. There exists potential hydrogen production from the raw gas of biomass steam gasification. In the present work, the characteristics of hydrogen production from biomass steam gasification were investigated in a small-scale fluidized bed. In these experiments, the gasifying agent (air) was supplied into the reactor from the bottom of the reactor and the steam was added into the reactor above biomass feeding location. The effects of reaction temperature, steam to biomass ratio, equivalence ratio (ER) and biomass particle size on hydrogen yield and hydrogen yield potential were investigated. The experimental results showed that higher reactor temperature, proper ER, proper steam to biomass ratio and smaller biomass particle size will contribute to more hydrogen and potential hydrogen yield.

Propagation and Decay of Concentration Wave in the Liquid–Solid Pulsed Fluidized Beds

JIN Guo-dong; LIU Da-you; SHU Chi-wang

. 2002, 2(5):  0-0. 

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Experiments were conducted in three swirl mist separators, with the internal diameters being 340, 480, and 700 mm, respectively. The separators were equipped with 18 sets of swirl vanes. The effects of superficial gas velocity and geometrical parameters, such as the elevation and the radial angle of the swirl vane, vane number, the ratio of separator body height to diameter on mist separation efficiency and pressure drop were tested. Results showed that the separation efficiency and pressure drop increased as elevation, radial angle and vane number were increased. An optimal superficial gas velocity exists in the range from 5 to 9 m/s and it decreases slightly with scale-up. The optimal distance between the swirl vane and inner exiting tube is 32%~73% of the separator diameter. The mist separator should be designed to make the separation efficiency as high as possible, with the pressure drop less than 2 kPa. The structure of the swirl vane is one of the most important parameters by which pressure drop is determined. A pressure drop correlation was established based on experimental data and theoretic analysis. A scale-up procedure was suggested for the design of industrial mist separators. Pressure drops measured from two industrial scale separators (f1.52 m and f1.90 m) were found in good agreement with the predicted values, and the separation efficiency of greater than 95% was achieved.

Cultivation of Dunaliella salina in an Airlift Photobioreactor

HAO Jian-xin; CONG Wei; KANG Rui-juan; CAI Zhao-ling

. 2002, 2(5):  0-0. 

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The separation property of membrane is related to the aperture structure of the membrane. In this paper, the chitosan ultrafiltration (UF) membrane was immersed into a coagulation bath with proper concentration and temperature and its aperture structure was modified. The results showed that the retention rate of chitosan membranes increased by 83.7% after being treated by precipitation. The retention rate, flux and aperture structure of chitosan membranes were affected by temperature of the coagulation bath, concentration of gelating agents and time of immersion precipitation. It is necessary to select appropriate parameters to enhance the separation property of chitosan UF membrane.

Investigation of Surfactant–Stain–Metal Interaction: Naphthochrome Green/Cetyltrimethylammonium Bromide/Rare Earths Ternary Complexation

ZHENG Li-xin(郑立新);SHEN Rong(沈荣);GAO Hong-wen(郜洪文)

. 2002, 2(5):  0-0. 

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The solubility of the three component system H3BO3–NaCl–MgCl2–H2O at 25 and 100oC has been measured. On the basis of the phase diagram constructed, the process technology of producing H3BO3 by hydrochloric acid decomposition from certain Ulexite in Tibet has been analyzed.

Self-assembly Mechanism and Defect Analysis of Colloidal Silica Photonic Crystals

ZHAO Xiao-feng; ZHANG Hui; TANG Qing

. 2002, 2(5):  0-0. 

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A strain Pseudomonas sp. ZJU-02 was screened from 7 strains. The strain had high lipase producing ability proved by the Rodamine B plate method. The results in shake flask cultivation showed that the suitable lipase producing media were: corn steep 3%, vegetable oil 1%, K2HPO4 0.1%, KCl 0.05%, MgSO4 0.05%, Tween 80 0.05%. Under optimal culture conditions (26oC and pH 6.5), the maximal lipase activity could reach 86 IU/ml. This enzyme was stable under 70oC and pH 7~10.5. The optimal conditions for the enzymatic reaction were 40oC and pH 9.5. This enzyme showed a good potential application in detergent and tan industry.

Portable X-ray Photography of Solid Concentration in Gas–Solids Fluidized Beds — (I) Principle and Image Processing

ZHANG Zhi-pan; LIU Hui-e; LUO Guo-hua; WANG Zhan-wen; WEI Fei

. 2002, 2(5):  0-0. 

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Presuming axial symmetry for the solid concentration, the portable X-ray photography technique was improved and applied to measure the radial solid concentration in a riser of a circulating fluidized bed. The principle and image processing are briefly introduced. Twenty to thirty images with 100~200 ns X-ray pulses were processed to get a time-averaged concentration profile. The main steps of this technique include getting photos, deducting the background, calibrating mass thickness map, and regressing calculation. As a demonstration, the radial profile of solid concentration in a f192 mm riser was determined and compared with correlations in the literature.

Leaching of a Low-grade Refractory Tantalum–Niobium Ore by KOH Sub-molten Salt

ZHOU Hong-ming; ZHENG Shi-li; ZHANG Yi

. 2002, 2(5):  0-0. 

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A new leaching process for a low-grade refractory tantalum–niobium ore by KOH sub-molten salt was studied. The effects of leaching temperature, initial KOH concentration, leaching time and mass ratio of alkali to ore on the leaching rate of Nb and Ta were investigated. The results show that the leaching rates of Nb and Ta can be raised as high as 98% and 96% respectively, 10% higher than those of the hydrofluoric acid process. Thus, the utilization rate of the refractory tantalum–niobium resource was greatly improved. In the process, KOH sub-molten salt was used as reaction medium to substitute the highly concentrated and toxic HF solution of the traditional process. Consequently, the pollution of F– was eliminated at the source. This provides a new way for extracting Nb–Ta from the tantalum–niobium ore.

Treatment of Coking Wastewater Using the Micro-electrolysis-SBR Activated Sludge Process

ZHANG Wen-yi

. 2002, 2(5):  0-0. 

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Challenges and opportunities to antibiotics are reviewed. Antibiotics, which have greatly enhanced human health, now are facing the issue of drug resistance of pathogen microbes and newly found diseases. However, modern biotechnology, including genomics, proteomics, bioinformatics and bio-macromolecular crystallization, is providing new ideas and methodology for the research and development of new pharmaceuticals.

Application of Experimental Design to Optimizing the Medium of Nuclease P1

XU Zheng-jun; XIAO Lin-ping; LU Hao; XIE Ning-chang; YING Han-jie

. 2002, 2(5):  0-0. 

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Hydrolysis characteristics of Ti(OC4H9)4 in the Ti(OC4H9)4-C2H5OH-H2O system were investigated for the preparation of TiO2 thin films via the sol-gel process. Experimental results are given about the effects of the system acidity (or basicity) and the addition of acetylacetone and AgNO3 on the viscosity and gelation time of the system. It was found that the introduction of AgNO3 can greatly improve the stability of the sols and prolong the gelation time besides adjusting pH and adding acetylacetone

Phase Transition and Transition Temperature Hysteresis of VO2 Thin Film

HU Zai-yong; XU Chu-shao; YANG Shao-li; CHEN Guang-bi

. 2002, 2(5):  0-0. 

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The VO2 thin film was prepared by the colloid method with industrial V2O5 as raw material. The properties of the VO2 film such as resistance abrupt drop temperature, phase transotion temperature hysteresis are examined. The results show that the VO2 thin film phase transition temperature is 35oC. Preparation method and substrate show greater effect on resistance abrupt change order, which can reach 2~3 order if common glass or quartz glass were employed in underlay by H2 reduction process, while it can reach 1.5~2 order of magnitude by N2 thermal decomposition. The resistance abrupt change order of magnitude is larger for VO2 film with quartz glass as substrate, the transition temperature hysteresis is 1~6oC, and closely related with the resistance abrupt change order, underlay, substrate and preparation method.

Fractal Model of Building Blocks for Pore Structure of Particles

MA Xing-hua; WANG Lu-ying; WAN Ming-rei; DENG Tong

. 2002, 2(5):  0-0. 

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Two fractal bodies of building blocks, cube and tetrahedron were structured and a general building blocks model was obtained, from which three fractal equations on surface area, volume increment, and their interrelation were derived to describe the pore structure of porous particles. The experimental results show that surface fractal dimension can be calculated from the data measured experimentally by mercury porosimetry or the BET method using the fractal equation on surface area and volume increment. The same value of fractal dimension can be obtained from the two methods for certain kind of porous particles. The geometrical meaning of surface fractal dimension and the calculation method of volume increment were also discussed.

Biosynthesis of Polyhydroxyalkanoates by Ralstonia eutropha with Short-chain-length Organic Acids

YAN Qun; DU Guo-cheng; CHEN Jian

. 2002, 2(5):  0-0. 

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Separation of dimethyl carbonate (DMC) and methanol (MeOH) is very difficult due to the azeotrope of DMC and MeOH, the pressure swing method is an effective method for separation of DMC and MeOH azeotrope. In this paper, a joint process of high-pressure distillation and atmospheric distillation was investigated. Binary interaction parameters of the UNQUAC model between MeOH and DMC were regressed against experimental data of vapor liquid equilibria of MeOH and DMC, the applicable range of the model is: pressure 0.1~1.5 MPa, temperature 337~440 K. Based on the thermodynamic model, the separation flowsheet, inclnding a high-pressure distillation column and an atmospheric distillation column in series, was simulated and analyzed. Sensitivity of operation factors was discussed and the optimum operation parameters were proposed. The optimal parameters of the high-pressure distillation column were as follows: stage number 40, feed stage 29, reflux ratio 7~10, operation pressure 1.0~1.5 MPa.

Production of Citric Acid from Apple Pomace Enzymolyzed by Cellulase

SONG Ji-rong(宋纪蓉);HUANG Jie(黄洁);XU Kang-zhen(徐抗震);ZHAO Qiao-yun(赵巧云)

. 2002, 2(5):  0-0. 

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Cellulase can evidently increase the content of glucose and has a significant effect on the production of citric acid from apple pomace by Aspergillus niger. Based on experiments, a cellulolytic enzyme named cellulase A6 was found able to produce about 170 g glucose from 1 kg dried apple pomace after 12 h reaction, with cellulase concentration of 20 U/g in the medium at 50oC, natural pH without pretreatment of alkali. Using the treated apple pomace as a liquid state substrate, Aspergillus niger-C selected out was able to produce about 256 g citric acid from 1 kg dried apple pomace at 35oC in 3 d or 30oC in 5 d with flask rotation speed of 210 r/min, and the conversion of citric acid could reach 80% based on the amount of sugar consumed.

Effects of He-Ne Laser Irradiation on the Mutagenesis of Beauveria bassiana

YANG Ge; CHEN Hong-zhang; LI Zuo-hu

. 2002, 2(5):  0-0. 

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CaCO3 uniform nanoparticles with particle size of 10~30 nm were synthesized in quaternary W/O microemulsion solution containing Triton X-100, cyclohexane and n-pentanol. The reaction conditions were optimized on the basis of investigation of the influence of the ratio of water to surfactant, the concentration of reactants and the ageing time on the products. Transmission electron microscopy (TEM) was utilized to characterize the shape and size of the obtained nanoparticle products.