Table of Content

20 April 2012, Volume 12 Issue 2

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流动与传递

Solid-Liquid Suspension in a Vertical Three-impeller Stirred Tank

LI Yong-gang HUANG Xiong-bin;

. 2012, 12(2):  181-186. 

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In order to improve the related efficiency in a storage tank, the solid-liquid suspension by three CBY III impellers [0.174 m diameter (D)] was studied. The three CBY III impellers were symmetrically fixed in a stirred tank with the diameter (T) of 2 m and height of 0.8 m. The optimum installing location and height of agitators were determined by analyzing the deposition area and just-suspension blade tip speed for glass beads of average 100 mm. The results show that the minimum just-suspension speed appears at 0.285R (R, the radius of tank, m) away from the tank wall, and the liquid level of 0.3T is superior to the situations of 0.2T and 0.25T, meanwhile the liquid level between 0.2T and 0.3T has only weak influence on power consumption. The power consumption of vertical three-impeller stirred tank is 2.8 times as that of standard stirred tank (single vertical agitator), but a vast of manufacturing cost can be saved. Compared with the three side-entering agitators, the vertical three-impeller agitation can save 20% of the energy when solids have 95% suspension, and installation and maintenance are very convenient and concise. It can be concluded that the vertical three-impeller agitation has an extensive application prospect in industrial storage tanks.

反应与分离

Effect of Indole on Hydrodesulfurization Performance of NiMo/g-Al2O3 Catalyst in a Slurry System

LI Wei-kun XIANG Hai-ding WANG Tie-feng

. 2012, 12(2):  187-193. 

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Hydrodesulfurization (HDS) performance of the presulfurized hydrogenation catalyst NiMo/g-Al2O3 was studied using dibenzothiophene (DBT) as model compound with and without addition of 1000 mg/L indole (based on N) under 300℃ and 4.5 MPa. Sulfur content and species concentration were measured using micro-coulometric analyzer and gas chromatography-mass spectrometry, respectively. The fresh and used catalysts were characterized by BET, XRD, TEM, TPD and TGA. The results showed that the addition of indole slightly increased the reaction rate in the activation period, but significantly decreased the rate in the subsequent stable reaction period, leading to an overall decrease in desulfurization rate from 70% to 58%. The used catalyst did not change in surface topography and crystalline structure compared with the fresh catalyst, but showed an increase in specific surface area. The addition of indole caused 12% decrease in the catalyst pore size and 50% increase in coke formation, and significantly deceased the production of cyclohexyl benzene, indicating that the hydrogenation desulphurization route was suppressed.

Alkylation of Isobutane with Ionic Liquid-Triflic Acid Coupled Catalyst

WANG Peng ZHANG Zhen LI Hai-fang ZHANG Peng LAN Ling ZHAO Guo-ying

. 2012, 12(2):  194-199. 

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A series of task specific ionic liquids based on imidazolium and pyridine with BF4-/CF3SO3- anion were synthesized through quaternary ammonium metathesis and protonation reaction. The above ionic liquids coupled with triflic acid were applied to catalyze the isobutane alkylation. Excellent alkylate quality with high C8 selectivity (81.8%), the ratio TMP to DMH at 8.36 and high research octane number 95.3 were obtained by tuning the type and content of ionic liquids. The coupled catalyst can be recycled for six times without significant loss of activity.

Study on Leaching of Cobalt White Alloy by Acidithiobacillus ferrooxidans

HU Guo-hong XIAO Li FANG Zheng ZHONG Hui

. 2012, 12(2):  200-205. 

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Acidithiobacillus ferrooxidans (A.f) was used for leaching of the hard cobalt white alloy. The experiments determined the optimum pH value and temperature in the presence of A.f to be 2.0 and 30℃, respectively. Three modes of treatment of the bacteria, which are directly inoculated with 107 cells/mL in 9K culture medium, dispersed to 107 cells/mL in iron-free 9K culture medium and beforehand adapted by the alloy and collected by centrifugation, were used. The result showed that for the first mode, it took 6 d to finish the leaching of cobalt and 8 d for copper with decrease in number of the bacteria in leaching. For the second one, it needed 3 and 7 d to dissolve cobalt and copper out, respectively, and accompanied decrease in the bacteria. And for the third one, the modified A.f could be increased to 108 cells/mL, and the leaching of two metals was for 2 d and 5 d, respectively. In the leaching process, pH value increased first and then decreased. The electric potential increased with the leaching of copper. With the bacteria which were beforehand adapted by the leaching of cobalt white alloy, its leaching residue contained a little ammonium jarosite and the leaching rates of cobalt and copper were 99.50% and 99.0%. The leaching mechanism of copper in cobalt white alloy by A.f was the indirect effect.

Measurement of CO2 Solubility in Tributyl Phosphate

CHEN Hao TANG Qing; TU Wei-xia BAO Wei-jun LI Shao-peng

. 2012, 12(2):  206-211. 

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The solubility of CO2 in tributyl phosphate (TBP) solvent was measured in a temperature range of 303.15~363.15 K and gas pressure of CO2 up to 4.5 MPa by the constant volume method. The results showed that the solubility increased with the augment of CO2 gas pressure and decreased with the rising of equilibrium temperature. GC/MS and FT-IR analysis results indicated that the capture process of CO2 by TBP could be regarded as physical absorption. The Henry's coefficient which was obtained by fitting of the experimental data was well consistent with the Henry's law. It confirmed that there was no chemical change during the adsorption process. Comparing the absorption capacity of TBP with other solvents, the CO2 solubility in TBP was 1.4 times higher than that in ethanol and 0.2 times higher than that in N-methyl-2-pyrrolidone under the same conditions.

Dissolution Behavior and Kinetics of Fine Silica Powder in Dilute Alkaline Solution

ZHANG Jin-liang GUO Zhan-cheng; ZHI Xin TANG Hui-qing

. 2012, 12(2):  212-217. 

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The dissolution behavior and dissolution kinetics of fine SiO2 powder in dilute alkaline solution were studied. The effects of initial concentration of NaOH, reaction time and reaction temperature on the dissolution rate of fine silica powder were investigated. XRD was used to analyze the phases of fine silica powder and leaching residue. The results demonstrated that SiO2 dissolution rate increased with initial concentration of NaOH and reaction temperature. Dissolution apparent activation energy of the amorphous SiO2 of fine silica powder in dilute NaOH solution was 18 kJ/mol. Dissolution reaction was controlled by diffusion.

Co-extraction of Rare Earth and Iron from Baogang Tailings

ZHANG Li-qing ZHAO Ling-yan ZHOU Hua-feng YUAN Ben-fu

. 2012, 12(2):  218-222. 

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A novel dissolving-extraction process of Baogang tailings in the dilute sulphuric acid and then dilute hydrochloric acid was studied. The effects of reaction temperature and sulfuric acid concentration on dissolution rate of the rare earth and iron were investigated and the total amount of rare earth in the acid dissolution of Baogang tailings was determined by spectrophotometry. The leaching rate of rare earth was less than 8% and the leaching rate of iron higher than 94% in the sulfuric acid dissolution. Fe3+ in sulfuric acid dissolution was reduced to Fe2+ by industrial scrap iron. FeSO4 was extracted by ethanol at room temperature. Its purity was 98.21% and the over-all recovery rate of iron in the tailings 89.51%. The grade of REO in the dilute hydrochloric acid insoluble residue was 43.60% and their total recovery rate 78.82%. This study provides a new method for extraction and separation of rare earth and iron from Baogang tailings.

Adsorption Performance of Ionic Liquid [BPy]Br Immobilized on Activated Carbon to SO2

WEN Li-jing TIAN Jin-ping LV Yong-kang LI Bing-zheng MA Yan

. 2012, 12(2):  223-226. 

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The ionic liquid [BPy]Br was immobilized onto activated carbon (AC) via a facile incipient impregnation method. The SO2 adsorption/desorption performances of the immobilized ionic liquid were evaluated, and high SO2 adsorption capacity and rate achieved. Its capacity reached 49.5 mg/g with a N2/SO2 mixture gas containing 3300 mg/m3 SO2. The [BPy]Br/AC system could be reused for many adsorption/desorption cycles. The second adsorption rate reached 96.83%. The immobilized IL structure was determined. The immobilization resulted in the increase of the volume of pores small than 4 nm, the most noticeable change was in the size range of pores from 0.5 to 3 nm. After adsorption, the surface area decreased 47.5% with 29.5% decrease in the volume of microspores.

Mechanism of Solid State Reaction between CaCO3 and MoO3

ZHU Hang-yu LI Zheng-bang WANG Jin-qing YANG Hai-sen

. 2012, 12(2):  227-230. 

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Solid state reaction between CaCO3 and MoO3 was studied using non-isothermal thermal analysis method. On the basis of TG curve and extent of reaction, the chosen 13 solid reaction mechanism functions were fitted respectively. The Coats-Redfern method used for model fitting and kinetic parameter was calculated by slope and intercept. The results indicate that the reaction between CaCO3 and MoO3 begins at 450℃, its reaction mechanism belongs to random nucleation and growth with integral form g(a)=-ln(1-a), the apparent activation energy is determined to be about 170.2 kJ/mol with pre-exponential factor of about 1.3′107 s-1.

过程与工艺

Preparation Conditions of Char via Pyrolysis of Low-rank Particulate Coal in Oxygen-containing Atmosphere

ZHONG Mei GAO Shi-qiu ZHANG Zhi-kai YUE Jun-rong XU Guang-wen

. 2012, 12(2):  231-238. 

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Physicochemical properties of char made by pyrolyzing a kind of low-rank particulate coal in O2-containing atmosphere and a quartz sand fluidized bed were investigated. The tested conditions included coal particle size, O2 concentration, pyrolysis temperature and residence time. The char with fixed carbon content over 82%(w) and volatile matter below 7%(w) was obtained by pyrolyzing the coal with particle size of 1~13 mm at the temperatures above 850℃ in the atmosphere with O2 content not below 3%(j) for pyrolysis time not shorter than 120 s. With the increase of temperature from 650℃ to 950℃, the corresponding interlayer spacing (d002) of the crystallite structure calculated from the XRD intensities was in the range from 0.383 to 0.372 nm, indicating a gradually condensed and ordered structure. BET specific surface area first increased then decreased with O2 concentration, and reached its maximum 242.71 m2/g at O2 7%(j), corresponding to the highest oxidation reactivity of char. The char produced via long-time pyrolysis in the O2-contaning atmosphere lowered the specific surface area and reactivity due to the burn-off of some formed pores.

Combustion Characteristics and Kinetics of Blast Furnace Dust and Coal Blends

CHANG Jian SU Bu-xin ZHANG Jian-liang HU Zheng-wen KONG De-en WANG Guang-wei

. 2012, 12(2):  239-246. 

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Combustion characteristics and kinetic parameters of blast furnace dust and coal blends using non-isothermal combustion method were studied by thermo-gravimetric balance. The combustion characteristic parameters of samples in different ratios, such as ignition temperature, peak temperature at the maximum weight loss rate, burnout temperature and the maximum combustion rate, were studied by thermo-gravimetric analysis, and the kinetic parameters such as activation energy Ea and frequency factor A were also investigated. The experimental results showed that Ea and A both decreased with increasing of blast furnace dust content in the blend, and the "kinetic compensation effect" existed in the two parameters. Ea decreased in the first and second stages of combustion of blast furnace dust and coal blends, but the influential degree changed largely for different coals. The calculation results of Ea showed that the blast furnace dust could improve the ignition property of coal, moreover there existed a synergistic effect in the combustion of blast furnace dust and coal blends, with the best property of 5% blending.

Influences of Zn, Fe and Cu Impurities on Electrorefining of Aluminum in BMIC-AlCl3 Ionic Liquid

PEI Qi-fei HUA Yi-xin LI Yan GONG Kai WANG Rui RAO Shuai LI Pi-qiang

. 2012, 12(2):  247-252. 

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The effects of Zn, Fe and Cu impurities on electrorefining of aluminum in 1:2 molar ratio BMIC-AlCl3 ionic liquid were investigated. The results showed that the potentials of Zn(II)/Zn, Fe(II)/Fe and Cu(I)/Cu were 0.21, 0.63 and 0.64 V vs. Al(III)/Al, respectively, which were much smaller than those in aqueous solutions. Constant current electrorefining experiments at 80℃ and 100 A/m2 current density indicated that the Zn, Fe and Cu in Al alloy anodes were removed almost. With increasing of Zn, Fe and Cu concentrations in anodes, their content in the Al deposit increased, but the depletion factor decreased, and the current efficiency was kept above 94%, and the energy consumption was between 1.59 and 1.74 kW×h/kg. The Al deposit with the purity higher than 99.8% obtained at cathode was dense and compact via electrolysis of aluminum alloy with 75.3%(w) Al.

Characteristics and Kinetics of the Pyrolysis of Coking Coal Tailings

LIU Hai-bing GUO Zhan-ying HUI He-long FU Xing-min LIU Shu-cheng LI Cheng SHU Xin-qian

. 2012, 12(2):  253-258. 

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The effects of final temperature and heating rate on the pyrolysis characteristics of coking coal tailings were examined by fixed-bed reactor and TG analysis. The results show that the pyrolysis process of tailings can be divided into three stages: from ambient temperature to 400, 400~600 and 600~950℃. By comparing the TG-DTG curves of coking coal and tailings, their weight loss curves are basically similar and the DTG peak of tailings shifts toward higher temperature range. On this basis, the tailing pyrolysis kinetics model, using Coats-Redfern equation, shows that the activation energy of the pyrolysis of tailings is 22.6~66.2 kJ/mol and the pyrolysis process can be described as three second-order reactions. The experimental results in the fixed bed reactor with 30 g charge show that below 600℃ there is a little hydrogen formation and below 400℃ little hydrogen. The reaction remarkably occurs after 600℃, where the yield of hydrogen is increased simultaneously. The yields of gas and hydrogen are respectively 4300 and 1722 mL, at finial temperature 950℃ by 30 g tailings charge 7950 and 2716 mL by the same coking coal, and the yield of hydrogen-rich gas accounts for 54% of the total gas of coking coal, the tailings have a good yield and reuse value.

Morphology and Size Distribution of Calcium Sulfate Dihydrate Crystals Precipitated from Simulated Acidic Wastewater by Lime

DENG Li-cong ZHANG Yi-fei CHEN Fang-fang WANG Shao-na

. 2012, 12(2):  259-264. 

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The effects of process parameters and addition of Mg2+ and Fe3+ ions on the morphology and size distribution of calcium sulfate dihydrate (gypsum) particles produced by the reactive crystallization between simulated acidic wastewater and lime were investigated. Compared with the stirring speed, addition rate of lime slurry and concentration of Ca(OH)2, reaction temperature significantly affected the morphology and particle size distribution of calcium sulfate dihydrate. The morphology of precipitated crystals evolved from platelet-like and needle-like shapes to rod-like shape when the temperature increased from 25 to 70℃. And the crystallization of gypsum slowed significantly in the presence of Mg2+ and Fe3+ ions in the solution. Moreover, the morphology of gypsum was transformed from platelet-like to rod-like shape with over 1945 mg/L Mg2+ concentration in the solution. The simulated industrial acidic wastewater containing heavy metals was efficiently purified by the two-stage neutralization technology, and highly agglomerated gypsum precipitates with rod-like shape were obtained.

Phase Transformation during the Reduction Process of Copper-containing Slag with Hydrogen

LIU Hui-li HU Jian-hang WANG Hua WANG Chao LI Juan-qin

. 2012, 12(2):  265-270. 

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The experiment of copper-containing slag reduction with hydrogen was carried out. XRD, FT-IR and SEM/EDS were used to examine the effects of temperature and reduction time on phase composition and surface morphology of the slag before and after reduction. The analysis results show that the reduction products of slag are metallic Fe and vitreous SiO2. The production of Fe and SiO2 increases with increasing of temperature and retention time. The iron conversion rate at 950℃ for 6 h is increased by 47.4% in comparison with that at 800℃ for 6 h. The iron conversion rate is highest at the early stages and decreases as time proceeds until the end of the reduction. The fayalite phase in the initial slag with the morphology of dendritic growth and long-narrow crystal is transformed to metallic Fe phase with the morphology of irregular grains and flakes. With the increase of temperature and retention time, the surface of metallic Fe grains becomes more compact. The optimum reaction conditions for production of metallic Fe catalyst from the slag reduction with hydrogen are temperature 900~950℃, and retention time 3~5 h.

Prediction Model of Intermixing Slab Length and Location in Continuous Grade Transition Casting Process

BI Jing-han TANG Ping WEN Guang-hua DING Ling SU Gang

. 2012, 12(2):  271-276. 

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Taking the No.1 continuous caster of Chongqing Iron and Steel Co. as object, water model experiments were conducted to simulate the continuous grade transition casting process. The dimensionless concentration profiles along slab length with different continuous casting conditions were measured. The results show that increasing molten steel flow rate and reducing molten steel level in the tundish can both reduce the intermixing slab. In the ranges of molten steel flow rate and level in Chongqing Iron and Steel Co., the flow rate will make a 21% difference from dimensionless concentration at the same time, the molten steel level will make a 73% difference from dimensionless concentration at the same time. This proves that the molten steel level has a more significant impact on dimensionless concentration. Based on the profiles, a model was developed to predict the length and location of intermixing slab and make the model exactly by sampling. Comparison of predicted dimensionless concentration profile with plant data shows that the precision of the model can reach 95%, it is higher than the similar results in other literature.

生化工程专栏

A New Method to Control the Coupling Site of Protein Ligands and Affinity Chromatographic Media

FENG Jing HUANG Meng-jun ZHANG Gui-feng KONG Ying-jun Gao Jian-Ping HUANG Yong-dong; SU Zhi-guo

. 2012, 12(2):  277-282. 

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Lysozyme was coupled on Sepharose 4FF media activated with 1,4-butanediol diglycidyl ether. HPLC-MS and enzymatic digestion were used to identify the coupling sites of lysozyme on the media. The effects of epoxy group density and the coupling reaction condition on the coupling sites were investigated. It was found that K96 was the main coupling site on the media when the epoxy group density was 11.34 mmol/g and pH 9.5. The coupling reaction time did not affect the coupling site. Epoxy group density and pH value during the coupling reaction are the main factors affecting the coupling sites of lysozyme on the media. More lysozyme molecules were coupled on the media via K33 and K97 when pH value was above 10.5.

Investigation on Enzymatic Synthesis of L-Theanine with Zinc(II)-L-Glutamine Complex and Its Mechanism

HU Guo-mei; YAO Zhong WANG Hao-qi; ZHOU Zhi XIONG Qiang XU Hong WEI Ping

. 2012, 12(2):  283-287. 

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To restrain the side reaction of autotranspeptidation, the complex of L-glutamine-Zn(II) [Zn(Gln)2] was prepared and used for enzymatic synthesis of theanine via g-glutamyltranspeptidation (GGT) reaction. The stability and reactivity of Zn(Gln)2 were satisfactory under the reaction conditions. Moreover, autotranspeptidation was restrained effectively when Zn(Gln)2 instead of L-glutamine (Gln) was used as the g-glutamyl donor. The kinetic parameter Km of B. subtillus GGT toward Zn(Gln)2 and Gln was calculated to be 0.53 and 1.01 mmol/L respectively. Under the conditions of 6 mmol/L Zn(Gln)2, 200 mmol/L ethylamine, and 0.5 U/mL GGT, 7.38 mmol/L of theanine was obtained after incubation at 37℃ for 2 h, indicating an increase of 14.42% compared with that using Gln as the donor substrate.

Optimization of g-Polyglutamic Acid Production by Bacillus licheniformis P-104

ZHANG Ye-wei WEI Xue-tuan HU Zhong-bo LUO Ming-fang XU Lin LIU Hui-zhou

. 2012, 12(2):  288-292. 

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The fermentation conditions for g-polyglutamic acid (g-PGA) production with Bacillus licheniformis P-104 were optimized in flasks, and the mesoscale batch fermentation was performed in a 6.6 L fermentor. The results showed that high yield of g-PGA with ultra high molecular weight (over 2500 kDa) was obtained under the optimal conditions (g/L): glucose 80, sodium glutamate 70, sodium citrate 10, (NH4)2SO4 10, MnSO4 0.15, MgSO4 0.8, K2HPO4 0.6, NaNO3 4, inoculation time 8 h, inoculum amount 3%(j), initial pH value 7.5, 37℃, and 180 r/min. In the flask fermentation, the maximum g-PGA yield reached 44.7 g/L for 24 h, and the highest specific productivity was 1.49 g/(L×h), being twice of the ultra high molecular weight g-PGA reported previously. In a 6.6 L fermentor, 32 g/L g-PGA was obtained for 33 h with a specific productivity of 0.97 g/(L×h).

材料工程专栏

Preparation and Characterization of Microencapsulated Phase Change Liquid Paraffin

XU Zhe LI jian-qiang;

. 2012, 12(2):  293-301. 

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As a novel type of low-temperature phase change materials, the microcapsules with the core of liquid paraffin and shell of melamine-formaldehyde resin (MF resin) were synthesized by using in-situ polymerization process. The effects of emulsion formulations, pre-polymerization conditions, shell material content and reaction time were investigated to obtain the optimized microcapsules. The as-prepared products under the optimal conditions showed high quality, their surface was smooth and dense, and free of any adhesion. The experimental characterization showed that in the microcapsules over 75%(ω) paraffin liquid was well encapsulated by MF resin, of which the thickness was in the range of no less than 50~100 nm. The microcapsule size was within the range of 1~5 μm and most intense distribution at 3.32 μm. DSC measurements gave two endothermic peaks with the initial phase change temperatures of 4.4 and 28.6℃ respectively, and the total enthalpy was 14.9 J/g which is comparable to the latent heat of commercial liquid paraffin. The microcapsules keep stable up to a high temperature 215℃ or a pressure of 1.0 MPa, as well as excellent thermal resistance against long-term thermal aging and thermal cycle near 300 times.

Synthesis of Ethylene Carbonate via Carbon Dioxide and Ethylene Oxide Catalyzed by Immobilized Ionic Liquid

WU Qing-hai REN Tian-rui

. 2012, 12(2):  302-309. 

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A new polymer ionic liquid catalyst PMHS-HEVIMBr was synthesized by four monomers of bromide 1-hydroxyethyl-3-vinyl imidazole (HEVIMBr), sodium methacrylate, 2-hydroxyethyl acrylate and styrene, and characterized in its structure. Then, the polymer ionic liquid was immobilized on the molecular sieve as solid catalyst particles for synthesis of ethylene carbonate (EC) via reaction of ethylene oxide (EO) with CO2. The effects of reaction time, temperature, pressure, catalyst concentration on the EO conversion rate and EC selectivity were examined. The results indicated that 95% of EO conversion rate and 98% of EC selectivity could be reached at the optimal conditions of reaction time 4 h, pressure 2.5 MPa, temperature 403.15 K and mass ratio of catalyst to EO 9%. The catalyst activity remained stable after 10 times of recycle, EO conversion rate had no significant loss, EC selectivity was close to 100%. The kinetic equation on the catalytic reaction process was obtain, r=-dCEO/dt=9.872×104e-52.00/(RT)CEO.

Synthesis and Application of Carboxylate Polyelectrolyte Dispersant

QIN Yue-jun REN Tian-rui PENG Tong

. 2012, 12(2):  310-316. 

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The carboxylate polyelectrolyte dispersant was synthesized with methacrylic acid (MAA), styrene (St), and hydroxypropyl acrylate (HPA) as monomers, and applied for production of pymetrozine suspension concentrate, and then its aqueous dispersion was investigated as the function of structure and chemical properties of the copolymer. The orthogonal experiments were carried out, and the optimal conditions were obtained as: MAA 50 g, St 20 g, HPA 20 g, and initiator ammonium persulfate 9%(w). The structure of SRF10 was confirmed by 1H-NMR and FT-IR, and its hydrophile lipophile balance was 14.47, critical micelle concentration 1.14 g/L (25℃), with good wettability and weak foamability. 25% pymetrozine suspension concentrate was processed with SRF10, obtaining favourable results of flowability, pourability, suspensiability and storage stability, which was similar to the dispersant YUS-SC3 abroad.

Fabrication and Characterization of Hierarchically Nanostructured Porous Carbonated Hydroxyapatite Coatings

LV Jun-ying GUO Ya-ping

. 2012, 12(2):  317-323. 

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Hierarchically nanostructured porous carbonated hydroxyapatite coatings (HNPCs) on Ti6Al4V substrate were fabricated by a two-stage application route: fabrication of nacre coatings (NCs) on Ti6Al4V substrate by electrophoretic technique, and conversion of NCs to HNPCs in a phosphate buffer solution (PBS) by microwave irradiation method. Their samples were characterized by using XRD, FT-IR, SEM, TEM, and N2 adsorption-desorption isotherms. The results show that the microwave irradiation technique improves obviously the conversion rate of NCs to HNPCs as compared with conventional method. After soaking the NCs in the PBS, calcium ions are released from the nacre particles and react with phosphate ions to form carbonated hydroxyapatite nanoparticles. These nanoparticles aggregate to form the plate-like carbonated apatite. The mesopores with a size of about 3.9 nm and macropores with the diameters of 1~4 mm exist within and among the carbonated apatite plates, respectively. Simulated body fluid immersion tests reveal that the HNPCs have a good in vitro bioactivity.

Synthesis of Polyacrylamide Na-bentonite Composite and Its Adsorption to Lead Ion

DU Xiu-juan CAO Ji-lin CHEN Xue-qing ZHAO Jian-jun

. 2012, 12(2):  324-329. 

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Polyacrylamide Na-bentonite composite was prepared by continuous process in which Ca-bentonite was modified by NaCO3 and then polymerized with polyacrylamide in aqueous solution. The composite was characterized by XRD, SEM, IR and TG-DTG-DSC. The adsorption experiments of the composite to Pb2+ and admeasurement of acrylamide monomer were investigated. The results showed that acrylamide intervened and polymerized in the layers of bentonite. The composite bentonite presented a lamellar structure and had better stability. The adsorption capacity of Na-bentonite composite was better than that of powder bentonite and Ca-bentonite composite, and increase with the rise of bentonite content. The adsorption capacity of composite Na-bentonite containing 90% Na-bentonite was 118.35 mg/g. The adsorption of Na-bentonite composite to Pb2+ was corresponding with a second-order kinetic model.

Flame Spray Synthesis of SnO2 Nanorods and Their Gas Sensing Properties

WU Zhi-wen HU Yan-jie LI Chun-zhong

. 2012, 12(2):  330-334. 

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SnO2 nanorods were synthesized by flame spray pyrolysis. Their morphology and structure were characterized. The as-prepared SnO2 nanorods grow along the (001) direction with the length of 200~350 nm and diameter of 30~50 nm. The effects of Fe doping and Sn4+ concentration on their morphology and growth mechanism were investigated. In the high temperature and rapid reaction process the Fe3+ could permeate in SnO2 crystals and promote their growth along the (001) direction. The gas sensing performance tests showed that the SnO2 nanorods exhibited more excellent gas sensing properties than SnO2 nanoparticles with a sensitivity of (12~100)′10-6 (j) ethanol as well as response and recovery times of 9.5 and 6 s, respectively.

Emissions Characteristics of Formaldehyde from Block Board

ZHANG Hao QIAN Fu-ping ZHU Qing-ming

. 2012, 12(2):  335-339. 

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Environment testing chamber of HJC-1 type was used to simulate the indoor environment of block board widely used in buildings adopted as the tested material. Formaldehyde concentrations in the chamber at different board structures, air exchange rates, relative humidities and environmental temperatures in a certain period were measured, and analyzed in its diffusion mechanism. Gray-system forecasting model was established to predict the concentration of formaldehyde, after its emission from the board at peak value. The results indicate that the main emission channel of formaldehyde is the side surface of board, it releases 3 times of formaldehyde quantity as the surface of board. Formaldehyde gas diffusion process is divided into three stages, the initial fast release, stable release and long-term slow release. Air exchange rate affects the formaldehyde concentration in the testing chamber, but does not affect its release rate of block board; the formaldehyde concentration increases with the increase of relative humidity and temperature. The predicted data of forecasting model agree well with the experimental data. The average relative error is 3.717%. This method is suitable for long term prediction.

Application of Film-forming Additives for Ionic Liquid Based Electrolyte

SUN Min-qian HU Zhi-qiang CAI Ying-jun DONG Tao LU Xing-mei

. 2012, 12(2):  340-344. 

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N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide was synthesized for the application in ionic liquid based electrolytes in lithium ion battery, 10% vinylene carbonate (VC) and 10% 1,3-propane sultone (PS) were added to the electrolyte system respectively as additives to improve the property of solid electrolyte interface and cyclic performance. The results of cyclic voltammetry showed that homogenous and compact solid electrolyte interface film formed on graphite electrode which was detected by observing the morphology of cycled graphite anode. Charging and discharging performance of LiFePO4/Li half cell was tested in the electrolyte with or without additives. The initial specific discharging capacities were increased to 129.4 and 123.0 mA×h/g by the addition of VC and PS, respectively, compared with that of additive-free electrolyte. The discharging retentions were 88.9% and 84.6% in electrolyte containing VC and PS after 10 cycles.

Preparation of Four DSAs and Comparison of Their Electro-catalytic Activity

JI Yue-fei WEI Jie WANG Dong-tian

. 2012, 12(2):  345-348. 

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Four different dimensionally stable anodes (DSAs) Ti/SnO2+Sb2O3, Ti/PbO2, Ti/Fe-PbO2 and Ti/SnO2+Sb2O3/Fe-PbO2 were prepared. Their surface morphology was characterized by SEM and polarization curves were investigated in H2SO4 solution. In order to explore their electro-catalytic activity, electro-catalytic degradation experiment was carried out with phenol as model organic compound. The research results indicated that Ti/SnO2+Sb2O3/Fe-PbO2 anode had the highest catalytic activity among the four anodes. The phenol removal rate reaches 95%. The accelerated lifetime of the electrodes with interlayer was improved obviously, reaching 16 h. In addition, the electro-catalytic degradation reaction of phenol on the four anodes followed first-order reaction kinetic law.

Regeneration of a Copper Based Catalyst for Sustainable Cl2 Production by HCl Oxidation

YANG Cheng-wu CAO Shuo ZUO Yi-zan HAN Ming-han

. 2012, 12(2):  349-352. 

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For the conversion of hydrogen chloride to chlorine, a kind of catalyst containing 8% copper was prepared by impregnation method. Its 300 h life test was carried out in a quartz fixed-bed reactor at 400℃, 0.12 MPa, molar ratio of O2 to HCl 1, and HCl weight hourly space velocity (WHSV) 0.8 h-1. It was found that HCl conversion rate decreased from initial 70% to 50% after 300 h evaluation. The deactivation mechanism of catalyst was due to the sintering of CeO2 and loss of active components. The deactivated catalyst can be regenerated by chlorinating at low temperature and making up active components.

综述

Research Progress in Non-carbon Materials Serving as Catalyst Support of Polymer Electrolyte Membrane Fuel Cells

YAO Chuan-hao LI Fan LI Xiang YANG Fan XU Meng-di XIA Ding-guo

. 2012, 12(2):  353-360. 

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The recent research progress in non-carbon materials supports, such as carbide, oxide, composite oxide and sub-stoichiometric titanium oxide, is reviewed. Their characteristics and preparation methods are described briefly. The emphasis focuses on the catalytic activity and stability of Pt based catalysts supported on the materials. Comparison has been drawn between non-carbon supported and commercial carbon supported catalyst (Pt/C). Finally, the defects of non-carbon materials are summarized and outlook for the future development of this kind of support materials and further investigation of mechanism are provided in light of the current research status, regarding the preparation of materials with high specific surface area, high conductivity and superior stability, as well as mechanism of strong metal support interaction.