Table of Content

05 May 2015, Volume 15 Issue 2

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流动与传递

Numerical Simulation of Gas-Liquid Two-phase Flow in a Bubble Column with Various Drag Models

LI Meng LI Xiang-yang WANG Hong-zhi XIE Yong-bing CAO Hong-bin

. 2015, 15(2):  181-189. 

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A 3D numerical simulation of gas-liquid two phases flow in a cylindrical bubble column was conducted with Euler-Euler two-fluid approach. The gas velocity on outlet boundary condition was corrected by user-defined function (UDF) custom programs, which could prevent the flows above the liquid level from forming eddy. The single bubble size model and population balance model (PBM) were used to calculate the bubble size separately, and the results by using the two models were compared. Three drag models (i.e. Schiller-Naumann, Grace and Tomiyama models) coupling with PBM were used and analyzed. The results show that the single bubble size model is no longer appropriate for the uniform air inlet boundary condition; The Abrahamson model in PBM, which is used for particle aggregation, can calculate the bubble aggregation if an appropriate Hamaker constant is set. The predicted results by using Tomiyama model coupling with PBM model are in good agreement with the existing results reported in the literature. The average gas holdup by using Schiller-Naumann model is about 40% different from the experiment value. The turbulent kinetic energy dissipation by using Grace model is 14.5% higher than the result of Tomiyama model, the errors of the predicted gas holdup distribution caused by using Grace model is 16.3%.

Flow Properties of Liquid Phase Systems in a Rotating Drum Bioreactor

TAN Tong WANG Zhi-hui WEN Shu-mei ZHANG Qing-hua WU Xia CONG Wei

. 2015, 15(2):  190-197. 

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Particle image velocimetry was used to investigate the flow profile of rotating drum bioreactor influenced by rotational speed and lifters with different numbers and configurations in two viscosity systems of tap water (m=1 mPa×s) and 8 g/L xanthan gum solution (t=10.97 Pa, m=1180 mPa×s). The results showed that for low viscosity water system, mean Y velocity was increased from 0.029 to 0.053 and 0.064 m/s, and global mixing performance and lifters hoisting capacity was promoted with the rotational speed from 4 to 12 r/min. With the increase of lifter number from 4 to 8, a more uniform flow field was obtained, and lifters hoisting capacity promoted by 32.5%. Compared with tap water, a more uniform flow field with more moderate shear stress formed in high viscosity system of 8 g/L xanthan gum solution.

Flow and Mass Transfer Characteristics in a Counter-Current Crossflow Gas-Liquid Impinging Scrubber

LI Guang-xiao WANG Zhao FAN Yi-ping LU Chun-xi

. 2015, 15(2):  198-204. 

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The effects of operating parameters on the flow pattern, mass transfer performance and local gas hold-up distribution are studied via the imaging method, dissolved oxygen method and double-sensor conductivity probe to reveal their relationship in a novel washing nozzle which can implement gas-liquid counter-current crossflow impingement. The results show that the flow pattern characterized only by direct observation method in some previous research can not describe it accurately because of the non-uniform gas-liquid racial distributions. Based on the imaging and local gas hold-up measurement, the flow pattern can be divided into five types: liquid column flow, annular flow and bubble flows (including the annular bubble flow and bowl-shaped bubble flow). Moreover, a new parameter Veff (effective mass transfer zone) in which the local gas hold-up (eg) ranges from 75% to 85% is proposed. It can be used to analyze the mass transfer effect of different flow patterns quantitatively. For any counter-current crossflow gas-liquid impinging scrubber, the mass transfer efficiency increases with the proposed parameter Veff.

Coupled Modeling of Flow, Heat Transfer and Solidification of Molten Steel in a Thin Slab Continuous Casting Mold

YUE Qiang ZHAI Zhang-xia PEI Xiao-hang ZHANG Jiong WANG Jian-jun

. 2015, 15(2):  205-211. 

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A three-dimensional coupled numerical simulation model of molten steel flow, temperature and solidification in the mold of a thin slab caster is presented using FLUENT software. The computational model section is 135 mm×1200 mm, and submerged entry nozzle has four outlets. F value is introduced to evaluate the liquid level fluctuation in the thin slab continuous casting mold. The molten steel flow, temperature distribution and solidified shell thickness variation are discussed. The results show that F value applied in description of liquid level fluctuation in the thin slab mold is feasible, when the casting speed increased from 1.44 to 1.80 m/min, the F value increased from 1.05 to 2.55. The relationship between the shell thickness (dshell) and solidification time (t) in the mold and secondary cooling zone is regressed as dshell=19.62t1/2-2.52, which basically agrees with the literatures.

Velocity Distribution of Particles in the Pre-lifting Structure with Two Strands of Catalyst Inlets with Central Tube

SHEN Qi FAN Yi-ping LU Chun-xi YAN Peng

. 2015, 15(2):  212-217. 

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The axial and radial distribution characteristics of FCC catalyst particle velocity in two catalytic cracking pre-lifting structures (with and without central tube) were investigated using PV-6D optical fiber probe. The radial non-uniform index was introduced to quantify the heterogeneity of particle velocity. The results show that the particle velocity in the structure with central tube is well distributed in the axial direction. In the expanding area (central tube area), the radial distribution of particle velocity in the structure without central tube is more uniform, while the particle velocity in the structure with central tube is more uniformly distributed in the bottom and riser entrance areas. In addition, compared with the traditional structure, the radial non-uniform index RNI(Up) in the riser of the structure without central tube is decreased by 40%, while RNI(Up) in the structure with central tube is decreased by 60%. The empirical model of axial distribution of cross-sectional averaged particle velocity in the structure with central tube was put forward. The calculated values are in good agreement with the experimental data, which can be used for the purpose of engineering design.

Flow Characteristics in a Three Impinging Jets Reactor

ZHANG Jun LIU You-zhi JIAO Wei-zhou QI Gui-sheng

. 2015, 15(2):  218-223. 

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The flow characteristics in a free three impinging jets reactor with the constant nozzle diameter of 1 mm were studied using high-speed digital camera. The effects of injection Reynolds number Reinj, distance between opposed nozzles d1, vertical distance between the vertical nozzle and opposed nozzles d2 on flow characteristics were examined. The experimental results showed that the effect of Reinj on flow structure was more significant at the flow rate ratio of 2. With increasing of Reinj, the flow structure was changed from a regular succession of ligaments to umbrella, finally becoming a structure composed of ligaments and droplets violent flapping which splashed around irregularly, performing high degree of atomization of the liquid sheets and intense perturbation of the edge of the liquid sheet, providing excellent mixing effect. Due to the small value of d1, the impinging zone close to the opposed nozzles, nozzle blocking could occur, leading to poor mixing. As d2 increased, the flow structure was slightly changed from a regular succession of ligaments to a small area of umbrella structure due to the effect of gravity at Reinj=1699. By using iodide-iodate parallel-competitive reaction system, compared with conventional impinging jets reactor, the value of segregation index of three impinging jets reactor was 1/2 as that of conventional impinging jets reactor at the flow rate ratio of 8, which led to higher micromixing efficiency.

反应与分离

Extraction Kinetics of Fe3+ and In3+ from Sulfuric Acid Medium with D2EHPA

RONG Hao LI Xin-bin WEI Chang ZHU Ru-long LI Min-ting DENG Zhi-gan

. 2015, 15(2):  224-229. 

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Extraction kinetics of trivalent In3+ and Fe3+ with di(2-ethylhexyl) phosphoric acid (D2EHPA, H2A2) in kerosene from sulfuric acid medium was studied using constant interfacial area method. The effects of temperature, interfacial area, stirring speed, hydrogen ion, D2EHPA and sulfate concentration on their extraction rate were examined. The results indicated that at 25℃ and stirring speed of 70~240 r/min, the apparent activation energy of In3+ extraction was 17.54 kJ/mol and the extraction process of In3+ was controlled by diffusion, while the apparent activation energy of Fe3+ extraction was 52.87 kJ/mol, Fe3+ was extracted in FeSO4+, and the extraction process was controlled by chemical reaction at the interface. As D2EHPA concentration increased, the forward reaction force could be increased to improve the extraction rate. Because the extraction process was the cation exchange, increasing the concentration of hydrogen ion would reduce the extraction rate. Complexation of metal ion with sulfate radical would reduce the extraction rate. Under those conditions, the rate of forward In3+ extraction reaction was expressed as -dCIn3+/dt=10-0.378 [In3+](aq)[H+](aq)-0.376[H2A2](org)0.158, and that of Fe3+ as -dCFe3+/dt=10-2.431 [Fe3+](aq)[H+](aq)-1.526[H2A2](org)0.600.

Study on Emission Characteristics of SO2 and Feasibility of Desulfurization in Iron Ore Sintering Process

LONG Hong-ming ZHANG Xiang-yang LI Jia-xin WANG Ping MENG Qing-min GAO Zhi-fang CHUN Tie-jun WU Xue-jian

. 2015, 15(2):  230-235. 

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The formation and emission characteristics of SO2 during iron ore sintering process were studied by sintering pot experiments. A new synchronous desulfurization technology was put forward by adding urea in wetting layer during sintering. The results showed that the concentration of SO2 in the pre-stage of sintering process was steadily maintained at a low level because SO2 generated in the pre-stage was absorbed by water within the material layer and accumulated in excessive moisture layer. When the wetting layer was dried by heating of high temperature exhaust gas, the SO2 absorbed by water released largely, rapidly reacted to form ammonium sulfate powder, and captured by dust, neither entering sintered ore nor discharge to the atmosphere with exhaust gas. The sintering pot simulation and industrial test showed that the desulfurization method resulted in significant emission reduction. Compared with the standard test, the emission concentration of SO2 declined from 694.2 to 108.0 mg/m3 in experiments, and the quality of sinter product was not affected. Moreover, compared with the traditional technologies, the new method provided a new low-cost, high-efficiency desulphurization technology for treatment of SO2 emission.

Flocculation and Settling Model of Licore Water-leaching Solution with Chitosan

ZHANG Jian-wei DING Xiao-guang FENG Ying QUAN Hao-yu

. 2015, 15(2):  236-241. 

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Chitosan was used to flocculate the licore water-leaching solution. The effects of pH value, the concentration of flocculant on flocculation rate, Zeta potential and settling velocity were examined. The results show that under the same pH condition, with the increase of flocculant dosage, the absolute value of Zeta potential first decreases and then increases, and the flocculation rate first increases and then decreases. In the range of effective flocculation, settling velocity increases with the increase of flocculant dosage. The optimal flocculant dosage is 0.347 g/L. The resulting solution has the highest clarity, flocculating rate can reach 93.58%, Zeta potential of 2.94 mV, the maximum subsidence velocity is 18 mm/min. Under the same condition of flocculant dosage, with the increase of pH value, the absolute value of Zeta potential first decreases and then increases, and the flocculation rate first increases and then decreases, settling velocity increases with the increase of pH value, the optimum pH value is 5, whereas the highest clarity of solution occurs, flocculation rate can reach 94.53%, Zeta potential is 2.04 mV, the maximum sedimentation velocity 15 mm/min. The closer the Zeta potential of experimental system to the isoelectric point, the more advantageous the flocculation of water leaching solution of traditional Chinese medicine. A settling velocity model was established through regression analysis on experimental data, and its rationality explained by the particle sedimentation theory in solid-liquid separation.

Separation of Cr3+ and Fe3+ from Sulphuric Acid Leaching Solution of Chromite by Goethite Method

LIU Jia-ning JIANG Mao-fa LI Yu-tong LIU Mei-shen

. 2015, 15(2):  242-246. 

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Separation of Cr3+ and Fe3+ from in sulfuric acid leaching solution of chromite with goethite was studied with experiments. The result show that Fe(OH)3 produced by adding appropriate amount of mineralizing agent (KOH) into Fe2(SO4)3 solution can be transformed into goethite inoculating crystals in good crystalline form under the conditions of 8 h heating at 120℃. After diluting the sulfuric acid leaching solution of chromite to the concentration of Fe3+ at 1 g/L and then adding goethite inoculating crystals to the solution, the separation between Fe3+ and Cr3+ can be accomplished under the conditions of pH 2.5 and 90℃ heating for 4 h. 97% of iron is precipitated and 33% of chromium lost.

Elimination of Aluminum in Nickel-Cobalt-Manganese Sulfate Solution

TAN Qun-ying TANG Hong-hui KONG Shui-lian CHEN Ruo-kui LIU Yong-qi LI Chang-dong

. 2015, 15(2):  247-251. 

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The separation of aluminum from nickel, cobalt and manganese in complexation-precipitation systems was studied. The relationships between metal ion concentration and pH value in the systems of Me-OH- and Me-OH--NH3 were simulated by thermodynamic calculation. Aluminum was eliminated of by hydrolysis-precipitation method. The results showed that separation of aluminum from nickel, cobalt and manganese in sulfate solution was effective in the Me-OH--NH3 and Me-OH--NH3-CO32- systems. When the pH value was 4.5, the recovery rate of nickel, cobalt and manganese was 98.57%, 99.63% and 99.91%, respectively, and the removal rate of aluminum 99.94%.

过程与工艺

Mathematical Model of the Reduction Process of Boron-bearing Iron Concentrate/Carbon Composite Pellets

SHEN Ying-feng XUE Qing-guo WANG Guang SHE Xue-feng

. 2015, 15(2):  252-258. 

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The kinetic characteristics of reduction of boron-bearing iron concentrate and Boudouard reaction are studied by isothermal thermogravimetric analysis in CO/CO2/N2 atmosphere. The activation energy is assessed as 194.72, 74.72 and 65.74 kJ/mol for Boudouard reaction and the reduction reaction stages of Fe3O4→FeO and FeO→Fe, respectively. On the basis of these kinetic parameters, a mathematical model of carbothermic reduction of boron-bearing iron concentrate is built up, which is validated by comparison of the computed results with the experimental data. The effects of pellet size, porosity and activation energy are discussed based on the calculated results. The increase of pellet size from f16 mm×8 mm to f32 mm×16 mm slows down the initial reduction rate, but elevates the ultimate metallization rate from 85% to 99.4%. The effect of porosity on the reduction process is relatively slight. The rise in activation energy of Boudouard reaction suppresses the proceeding of reduction, but has little impact on the ultimate metallization rate; When the activation energy of the interface reduction increases from 95% to 105% of the original value, not only the reduction rate decreases, but also the ultimate metallization rate declines from 99.59% to 94.81%. It can be deduced from the effect of activation energy that the reduction process is initially under the mixed control of interfacial reduction and Boudouard reaction, but under control of interfacial reduction in the later stage.

Numerical Simulation of Gaseous Combustion Process in Anode Furnace of Copper Refining with Two Types of Burner

LIU Wei LONG Peng CHAI Man-lin CHEN Juo YU Xiao-hua

. 2015, 15(2):  259-265. 

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Numerical simulation was carried out with CFD Fluent 6.3 software to investigate the gaseous combustion processes in the anode furnace of copper refining equipped with two different types of burner. The simulation results show that when the furnace is equipped with Type I burner, the peak temperature of the flame is 2301 K and the flame length 2.3R (R is the furnace radius) in the heat persevation period, while in the oxidation period, the peak value of the flame temperature increases to 2506 K and the flame length is 2.0R. When the furnace is equipped with Type II burner, the highest flame temperature is 2610 K and the flame length 1.85R in the heat persevation period, and the peak temperature of the flame is 2800 K and the flame length 1.82R in the oxidation period. The distribution of gaseous temperature inside the furnace is more uniform in the case of Type I burner, which meets the needs of copper refining process better as well. The burner structure and operational parameters (including natural gas velocity, outer oxygen velocity, side oxygen velocity) have significant influences on the gaseous combustion process in the anode furnace of copper refining.

Influence of Shale Ash on Pyrolytic Behaviors of Oil Shale

SHI Wan-jun WANG Ze DUAN Yue LI Song-geng SONG Wen-li

. 2015, 15(2):  266-271. 

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The effect of shale ash on pyrolytic behaviors of oil shale from the fourth layer of Gonglangtou mine, Huadian, Jilin Province, was studied by TG-FT-IR analyzer, and the effect of silica as chemical inert material used as reference. The weight loss and evolution of volatiles from the pyrolysis of mixed oil shale and shale ash were explained by analysing the variation of composition of the pyrolytic solid residue. The results showed that shale ash could promote the pyrolysis of both organic and inorganic matters in the oil shale. When the content of shale ash in the mixture was 83%, the weight loss of oil shale was increased by 1.92%, 3.39% and 18.99%, compared with oil shale mixed with silica in the temperature ranges of 300~600, 600~750, and 750~900℃, respectively. The on-line FT-IR analysis results showed that CO2 released before aliphatic hydrocarbons at lower temperature. At high temperatures (over 750℃), CO2 was merely generated from the pyrolysis of the mixture of oil shale and shale ash, which could be attributed to the promoted decomposition of carbonates under the effect of shale ash and the reaction between CaSO4 and carbon residue.

Combustion Characteristics and Kinetics of Mixed Coke Dry Quenching Dust and Low Ash Coal

LIU Guo-qing LIU Qing-cai YAO Lu REN Shan SUN Jian AO Wan-zhong LONG Ming-hua ZHANG Dong-sheng XIAO Yang-wu

. 2015, 15(2):  272-277. 

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Combustion kinetics of mixed coke dry quenching (CDQ) dust and low ash coal was investigated by thermogravimetric analysis from ambient temperature to 1173 K at 60 mL/min air flow rate under different heating rates, respectively. The results showed that CDQ dust content and heating rate had important effects on the combustion process of dust-coal blends. With the increase of CDQ dust content in the coal blends, the ignition temperature and burnout temperature decreased, the maximum loss rate and the combustible index increased, and the burning characteristic of the blends became better. The non-isothermal Flynn-Wall-Ozawa model was used to study the combustion kinetics of blends under different heating rates. When CDQ dust content varied from 0 to 10%, the activation energy decreased from 96.82 to 47.37 kJ/mol. Furthermore, adding 8% CDQ dust into the blends could decrease the activate energy of the blends effectively.

Study on Transformation of Minerals in Coking Process of Coals

QIU Shu-xing ZHANG Sheng-fu ZHANG Xi YANG Ming-rui LIU Wei

. 2015, 15(2):  278-283. 

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XRD and general structure analysis system were used to studied transformation of minerals in Nantong and Yonghun coals, and Nantong coal with additives in their coking process. The results showed that kaolinite at 46.03% of the ash content was decomposed completely, 65.24% of kaolinite decomposed to mullite, and the other 17.02% to cristobalite and γ-alumina. In addition, the quartz mineral content in the ash was increased from 19.57% to 35.48%. 89.53% of pyrite with the content of 7.83% in the ash was converted into pyrrhotite. Calcite with the content of 17.64% was decomposed completely, and partially converted into CaH2PO4. During coking process of Yonghun coal, the transformation rule of other minerals was similar to that of Nantong coal, except that calcite was mainly converted to oldhamite and anhydrite. Under the addition of CaO and Fe2O3 with the content of 5% of the coal into Nantong coal, the content of mullite was decreased by 4.80% and 5.68%, and that of quartz minerals by 21.17% and 20.07%, respectively. Adding reagents could improve the content of minerals containing calcium and iron in the coke, the coke reactivity index was increased by 31.45% and 15.05%, respectively.

Pulverization of Iron Ore Sinter in Low Temperature Reduction Process

LEI Chao WEI Yong-gang

. 2015, 15(2):  284-288. 

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The reduction degradation behavior of iron ore sinter under different temperatures was studied by adapting kinetic reduction to simulate a blast furnace process, and the influence of coal gas composition on the reduction degradation examined. The results show that the reduction degradation process of sinter in blast furnace can be divided into three stages, the most dramatic degradation behavior occurs between 400℃ and 600℃ as the second reduction stage, the reduction degradation index (RDI) can reach as high as 50.2%, accounting for 48.5% RDI of all reduction stages, the reduction index (RI) is still at a low value of 15.39%, only 17.9% of the whole reduction stage, the medium diameter of sinter decreases to 3.91 mm. Increasing the content of H2 can raise RDI to some degree, but the increment decreases. Increasing the content of CO2 in coal gas can somewhat decrease the DI, but the reduction slows down.

生化工程专栏

Preparation of Vinegar Residue Hydrolyzate and Its Fermentation for Production of Bacillus subtilis TS-02

LI Xiao-lian WANG Zi-qiang WANG Yun-shan; DONG Xiao-fang ZHANG Li-ping SU Zhi-guo

. 2015, 15(2):  289-294. 

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The feasibility of fermentation of Bacillus subtilis TS-02 vinegar residue was studied. The water heat treatment technology was adopted in vinegar residue preprocessing, the hydrolysis conditions of cellulase were optimized, and the vinegar residue hydrolyzate solution with the glucose concentration of 27.00 g/L was prepared. Instead of the glucose medium, the vinegar residue hydrolyzate was used as the based medium in fermentation experiments of Bacillus subtilis. The results showed that the viable number of 4.64×1010 mL-1 was obtained by using vinegar residue enzymatic hydrolysate after 44 h. The fermentation period of Bacillus subtilis in a 7 L fermentor was 22 h, the viable bacteria number reached 6.16×1010 mL-1 and spore production rate was more than 80%.

Preparation and Property Regulation of Charge-Collagen Double Acting Microcarrier

WANG Shao-jiu WANG Qi-bao LI Juan MA Guang-hui ZHOU Wei-qing;

. 2015, 15(2):  295-300. 

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Konjac glucomannan microspheres were firstly aminated with 2-diethylaminoethyl chloride hydrochloride (DEAE), and activated with 1,4-butanediol diglycidyl ether. Then the charge-collagen double acting microcarrier was prepared via the coupling of the collagen on the activated microspheres. Furthermore, the effects of coating conditions, activation methods of collagen, sources of collagen and DEAE dosage on the microcarrier cell culture were examined. The results show that the collagen layer of charge-collagen double acting microcarrier can be controlled to 5~50 mm. After culture for 2 h, the cells attached to about 4×104 cells/mL, the attachment rate is between Cytodex 1 and Cydodex 3. The growth rate is faster than Cydodex 1 after 96 h, and cell number is more than Cytodex 1 and Cydodex 3 in final 144 h, reaching 1.59×106 cells/mL.

Biodesulfurization of Immobilized Sulfur Oxidation Bacteria Thioalkalivibrio versutus D301 with Fe3O4 Magnetic Nanoparticles

XU Xiao-hui QIU Xiao-ling MU Ting-zhen ZHOU Jie-min BAI Bing SONG Zi-yu WU Dan GUAN Yue-ping XING Jian-min;

. 2015, 15(2):  301-306. 

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Magnetic Fe3O4 nanoparticles were synthesized by a coprecipitation method followed by modification with oleic acid, which was used for immobilizing Thioalkalivibrio versutus D301 cells. The process parameters of cell immobilization under halo-alkaline condition, the sulfur oxidation rate of free cells and immobilized cells and recycling ability of immobilized cells were investigated. The results indicated that the optimum immobilization conditions were that the cells were immobilized for 10 min at the conditions of 0.6 mol/L Na+, pH 9.5 and 20℃. The sulfur oxidation rate of immobilized cells was 81% of free cells after activation. The coated cells not only had good sulfur oxidation activity, but also could be reused six batch cycles.

Effects of Iron Oxidation Bacteria on Arsenic Precipitation and the Formation of Crystalline Scorodite from Arsenic-containing Solution

CAO Jun-ya YE Xu-wen DU Juan ZHAO Huan ZHANG Guang-ji

. 2015, 15(2):  307-312. 

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Under the conditions of atmospheric pressure, initial pH 1.5, molar ratio of Fe to As 1.5, different temperatures (35, 50, 70℃), and existence of scorodite seeds, the influences of iron oxidation bacteria, Acidithiobacillus ferrooxidans, Sulfobacillus sibiricu and Metallosphaera Ar (M.A), on precipitation of arsenic in Fe(II) solution containing As(V) and formation of crystalline scorodite were investigated. The results show that higher temperature, bacteria and scorodite seeds can effectively promote the removal and precipitation of arsenic in the solution. Especially at 70℃ with M.A and in existence of scorodite seeds, the removal rate of arsenic reaches 87%, and the precipitate scorodite can form as fine and large rhomboid crystals.

Synthesis of Salidroside with Cross-linked β-Glucosidase Aggregates in a Non-traditional Reaction System

HE Li-fei XUE Yuan-kai SHI Xian-ai

. 2015, 15(2):  313-317. 

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In a non-traditional reaction system with ionic liquid, mixed organic solvents and buffer solution, synthesis of salidroside with highly operation stable cross-linked b-glucosidase aggregates by direct glycosylation under enzymatic catalysis was studied. Based on the optimization of the composition of reaction media and the proportion of each component, the reaction system was determined as follows in volume ratio: 8.5% of ionic liquid C4MIm×PF6, 42.5% of 1,4-dioxane, 34.0% of ethyl acetate, and 15.0% of citric acid-disodium hydrogen phosphate buffer (pH 6.0). In this reaction system, the water activity was maintained at the proper level which was suitable to the direct glycosylation even though the water content of the system was up to 15%. So, at the reaction temperature of 50℃ and the rotating speed of 250 r/min, when b-D-glucose content was 100 g/L and p-hydroxyphenylethanol content 200 g/L, the equilibrium concentration of salidroside could reach up to 25.32 g/L after reaction for 120 h.

材料工程专栏

Preparation of Silica-supported Zirconium Sulfate and Its Catalysis in Esterification of Octyl Acetate

YE Jia-yi LU Ping HUA Chao;

. 2015, 15(2):  318-323. 

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A SiO2 carrier was prepared by Stober method, and Zr(SO4)2/SiO2 catalyst under different loadings and calcination temperatures prepared by impregnation method, which was used for synthesis of octyl acetate. The catalyst was characterized. The results showed that Zr(SO4)2 dispersed well on the surface of SiO2 at the calcinations temperature of 250℃ with 20% loading in Zr(SO4)2/SiO2. Under the optimum reaction conditions of Zr(SO4)2/SiO2 with 20% loading, calcining at 250℃ for 3 h, reaction temperature 120℃ and reaction time 3 h, n-octanol conversion rate reached 97.82%, and the selectivity to octyl acetate was 92.53%.

Preparation of Ruthenium Powder as Sputtering Target Material

ZHANG De-yu LEI Xin-you ZHANG Jian-bin

. 2015, 15(2):  324-329. 

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Osmium was separated from ruthenium hydrochloric acid absorption by H2O2 selective oxidation and vacuum distillation in a supergravitational rotating packed bed in the first stage. Ruthenium and residual osmium were separated in the stage. And with addition of NaClO3 and H2SO4, the residual solution was further treated by oxidation and vacuum distillation in the second stage. Ruthenium tetroxide (RuO4), which formed in the oxidation and vacuum distillation, was absorbed in a hydrochloric acid solution, and pure ruthenium hydrochloric acid absorption solution obtained. A suitable amount of H2O2 was added in the absorption solution, and the ammonium ruthenate chloride in crystalline form was obtained by crystallization and precipitation of the pure ruthenium hydrochloric acid absorption solution with ammonium chloride. The sponge ruthenium powder was prepared by calcining the resultant ruthenium salt under the optimum conditions of the calcination and reduction in hydrogen atmosphere. The sponge ruthenium powder product was washed firstly by a mixed solution of aqua regia and hydrofluoric acid, and further washed by water before drying. The high-purity ruthenium could be obtained with the purity of at least 99.999%, excluding gaseous ingredient elements, which could be used for preparing high-purity ruthenium sputtering target materials. The separation mechanism of osmium with ruthenium by selective oxidation and vacuum distillation was analyzed.

Synthesis of Geopolymer and Its Detoxication and Immobilization of Cr(VI)

CHEN Fang-ming CHEN Jie-yu

. 2015, 15(2):  330-335. 

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A geopolymer was synthesized using coal gangue as raw material, and water glass and sodium hydroxide as alkaline exciting agents. The geopolymer added by sulfide was used in detoxification and immobilization of Cr(VI). Then the curing geopolymer was tested. The results show that when the molar ratio of sulfide to Cr(VI) is more than 3:1, the leaching concentration of total chromium is less than 1 mg/L and the fixation rate of chromium above 99%. The best fixation rate of Cr(VI) is 1.2%. The detoxification and immobilization mechanism of Cr(VI) is due to oxidation-deoxidation reaction. S2- is oxidized to S2+ and Cr(VI) deoxidized to Cr(III) during the synthesis of geopolymer, then Cr(III) is attracted by -OAl(-)(OH)3 in the geopolymer and fixed in a non-crystalline structure.

Preparation of Ultrafine Silica Particles and Their Application in a-Amylase Immobilization

CAO Li-xia WANG Ling-ling LIU Hui-zhou YANG Chuan-fang

. 2015, 15(2):  336-340. 

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50 nm and 1 mm SiO2 particles were prepared using TritonX-l00 reverse micellar system and St?ber method, respectively. The particles were then modified with dichlorodimethylsilane to render their surfaces hydrophobic for immobilization of a-amylase. The results showed that compared with unmodified SiO2 particles, the adsorption capacity of a-amylase on modified SiO2 particles was obviously improved, and the stability of immobilized a-amylase was also effectively increased, as evidenced by only 30% loss of activity after 6 times washing. The adsorption capacity of a-amylase on 1 μm SiO2 particles was higher than that on 50 nm SiO2 particles, while the activity of immobilized α-amylase on the different carriers was ranked in the order of 50 nm SiO2 > 1 mm SiO2 > modified 50 nm SiO2 > modified 1 mm SiO2.

Competitive Adsorption of Toluene and P-xylene at Low Concentration on Microfibrous Entrapped Activated Carbon Composite in a Structured Fixed Bed

LIU Jian YAN Ying ZHANG Hui-ping

. 2015, 15(2):  341-345. 

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Microfibrous entrapped activated carbon composite was prepared by wet layer paper-making technique. The adsorption breakthrough behaviors of volatile organic compounds (toluene and p-xylene) on microfibrous composites in a structured fixed bed were studied. The results showed that the activated carbon particles were well entrapped into the locked three-dimensional porous networks. The specific surface areas of the activated carbon before and after entrapment were 976 and 955 m2/g, and the mircopore volumes 0.261 and 0.247 cm3/g, respectively. The adsorption of toluene and p-xylene in both individual GAC bed and structured fixed bed showed significant competitive effect. The breakthrough time for toluene was earlier than that for p-xylene in both beds. The breakthrough time of toluene and p-xylene in the structured fixed bed with microfibrous composite increased about 20 and 30 min respectively, compared with those in the individual GAC bed at 5% breakthrough concentration, and the separation time between toluene and p-xylene increased 10 min. The breakthrough curves fitted to Yoon-Nelson model. The results fitted well to Yoon-Nelson model with the correlation coefficients R2>0.98 and k' value of the structured fixed bed was 3 and 1.6 times larger, compared with that of individual GAC bed for toluene and p-xylene adsorption, respectively.

Preparation of Sodium Nitrate/Silica Composite as Shape-stabilized Phase Change Material via Sol-Gel Method and Its Characterization

GUO Qiang WANG Tao

. 2015, 15(2):  346-349. 

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NaNO3)/SiO2 composite was prepared as a shape-stabilized solid-liquid phase change material (PCM) by sol-gel method with Na2SiO3 as silica source. In this composite, the in-situ generated NaNO3 acted as the latent heat storage material, and SiO2 as the supporting material. Its chemical composition, morphology, structure and thermal properties were characterized. The results showed that the prepared composite PCM was a physical hybrid of NaNO3 and SiO2 only, NaNO3 was well dispersed in the porous network of SiO2. The composite had good thermal stability in the temperature range of less than 600℃, its phase change latent heats of melting and freezing were 144.1 and 142.6 kJ/kg, and the temperatures of melting and freezing 302.3 and 301.2℃, respectively. Furthermore, the NaNO3/SiO2 composite maintained good thermal energy storage and release ability even after 100 cycles of melting and freezing.

Preparation of Co0.5Zn0.5Fe2O4/PANI Composites and Their Electromagnetic Properties

PAN Le JIN Chuan-gui CHEN Yi-chuan

. 2015, 15(2):  350-353. 

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Spinel structured Co0.5Zn0.5Fe2O4 nano-particles were prepared by hydrothermal method, and different ratios of Co0.5Zn0.5Fe2O4 and polyaniline (PANI) composites were prepared by in-situ polymerization method. The composites were characterized. The results showed that there was the bond reaction between Co0.5Zn0.5Fe2O4 and PANI in the composites. In the frequency range of 2~18 GHz, compared with pure Co0.5Zn0.5Fe2O4, both the real and imaginary parts of dielectric constant of Co0.5Zn0.5Fe2O4/PANI composites increased, while both the real and imaginary parts of the permeability of them decreased. The maximum absorption peaks of composites were improved obviously, compared with the pure Co0.5Zn0.5Fe2O4, and their maximum absorption peaks were both about 15 dB in the frequency range of 11~13 GHz.

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Advances in Research of Devices for Wet Flue Gas Desulfurization

SONG Wei YUAN Zhi-guo LIU You-zhi KANG Xiao-feng LIU Hui-jun GAO Ya-jie

. 2015, 15(2):  354-360. 

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The improvement research of absorption column for flue gas desulfurization (FGD) and some new FGD reactors, such as falling film reactor, impinging stream reactor and rotating packed bed (RPB), is reviewed in details. The advantages and disadvantages of each device are compared. It is pointed out that the intensification technology of chemical engineering process is a new approach to solve the problem of low mass transfer efficiency and high investment costs for traditional column devices. Therein the application of RPB in wet FGD is of high value. The relevant research direction for industrial application is to develop a RPB that can deal with higher flow rate and intensify gas phase mass transfer process.