Table of Content

20 June 2008, Volume 8 Issue 3

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流动与传递

Model and Numerical Analysis of Dynamic Distributions of Dissolved Oxygen Concentrations in the Reactor of Bioartificial Liver Support System

LIU Jian-feng SONG Tao LI Rui-yu LI Ming LIU Guo-qiang

. 2008, 8(3):  417-424. 

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Based on the analysis of gas-liquid mass transfer and liquid flow in the reactor of bioartificial liver support system, and comprehensive consideration of the configuration and the actual needs of the reactor, the mathematic mechanism model of dynamic distribution of dissolved oxygen concentrations in the reactor was build up based on one-dimensional axial diffusion model. The equations set was solved by finite difference method and the effects of conditions, such as flow rate, oxygen mass transfer coefficient and oxygen consumption rate on distributions of dissolved oxygen concentration were investigated. The results show that the optimal parameters in the reactor are liquid flow rate 0.55 mm/s, mass transfer coefficient 0.31 s-1, and diffusion coefficient 0.02 mm2/s. Based on the experimental data, the model is proved and the average calculation error can be limited in ±5%. The results are of reference to the optimum design of the reactor in bioartificial liver support system, and this model provides a reliable theoretical basis.

Investigation of Turbulence Kinetic Energy Dissipation Rate in a Stirred Tank Using Large Eddy PIV Approach

LIU Xin-hong MIN Jian PAN Chun-mei GAO Zheng-ming CHEN Wen-min

. 2008, 8(3):  425-431. 

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The flow field of impeller region in a Rushton impeller stirred tank with a diameter of 0.476 m was measured using particle image velocimeter (PIV). Average velocity and turbulent kinetic energy k distribution were obtained. Turbulence kinetic energy dissipation rate e was estimated by using a large eddy PIV approach. Cross-correlation coefficient of e and k was calculated to analyze the relation between them. The results show that the large eddy PIV approach could effectively estimate e distribution. Impeller stream inclines slightly upwards, accompanied with two vortices on both sides of the stream. The incline angle of impeller stream and the distance between the centers of two vortices changes as the stream moves towards the tank wall. The incline angle increases before the phase angle q=40o, then decreases with the maximal value 13.2o at q=40o. The distance between the centers of two vortices decreases before q=20o, then increases with the minimum value 0.0387 (normalized by the tank diameter T) at q=20o. The peaks of turbulent kinetic energy and turbulence kinetic energy dissipation are both located in the vortex region near the jet flow. Average cross-correlation coefficient of e and k is equal to 0.363, the cross-correlation coefficient in the center impeller stream is larger than that in the other parts of the region.

Experimental Study on Particle Concentration Distribution in a Novel Cyclone Tube

SUN Zhi-qian JIN You-hai WANG Jian-jun ZHANG Yan

. 2008, 8(3):  432-437. 

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A novel cyclone tube design is obtained on the basis of structural and dimensional optimization of Shell-type cyclone tube. By using isokinetic sampling method, the particle concentration distribution in the novel cyclone tube is measured and analyzed. The experimental result demonstrates that discharge dust cone with slots has better separation effect, flowguide cone can reduce short circuit flow greatly and makes small grain separated because of the strong inertia. Particle concentration decreases with axial coordinates increasing above the ashpit, which indicates that the inner revolving flow has a strong secondary separation effect. The estimation on particle grade efficiency suggests that the novel cyclone tube can separate particles of 7 mm completely, for small particles of 3~7 mm, its grade separation efficiency is above 86%. On contrast, Shell-type cyclone tube can only separate particles larger than 10 mm completely in the same operation condition. This work provides a necessary basis for structural improvement, dimensional optimization and even industrial application of cyclone tube.

Experimental Study on Bed Density in a Novel Gas-Solid Annulus-lifted Air Loop Reactor

MengXi Liu XIE Jian-ping LU Chun-xi WANG Zhu-an

. 2008, 8(3):  438-443. 

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In order to overcome shortcomings of commercialized gas-solid draft tube-lifted air loop reactor, a novel gas-solid annulus-lifted air loop reactor (ALALR) was proposed. Experiment was conducted to investigate local bed density distribution. The circulation driving force increased with the increase of superficial gas velocity in annulus, but decreased with the increase of superficial gas velocity in draft tube, and even became negative when it reached 0.2 m/s. The bed density was influenced by configuration of ALALR and showed an ununiform radial distribution. The bed was not well fluidized below the draft tube (r/R≤0.47) with the bed density close to 820 kg/m3, but was well fluidized in the lower annular region (0.47≤r/R≤1.0) with the bed density lower than 450 kg/m3. When the superficial gas velocity in annulus increased from 0.2 to 0.54 m/s, the mean bed density in the annulus region and draft tube region decreased about 70 and 33 kg/m3, respectively. Interestingly, with the increase of the superficial gas velocity in draft tube from 0.06 to 0.2 m/s, the mean bed density increased about 90 kg/m3 in the annulus region, but decreased to about 33 kg/m3 in the draft tube region.

Gas-Liquid Dispersion by Hollow-blade Disk Turbines

ZHANG Xin-nian LIU Xin-wei BAO Yu-yun GAO Zheng-ming

. 2008, 8(3):  444-448. 

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The influences of impeller diameter (0.28T, 0.33T, 0.40T and 0.5T) on critical impeller speed for gas dispersion, gassed power consumption and gas holdup were studied in a 0.476 m i.d. stirred tank with dished base agitated by a hollow-blade disk turbine. The results show that the flooding transitions measured from loading to flooding (L-F) and from flooding to loading (F-L) by means of increasing and falling gas rates show a hysteresis for low D/T, which becomes indistinct with the increase of D/T. At certain gas rates, D/T has no effect on relative power demand (RPD, the ratio of gassed power to ungassed power). For given power consumption, gas holdup increases slightly with increasing D/T at low gas rate, whereas it decreases apparently at high gas rate. The results and the correlations are of particular relevance to the design and operation of sparged gas-liquid stirred reactors.

Simulation of Current Distribution in Manganese-Silicon Ferroalloy Smelting Arc Furnace with Coke Layer

CHU Shao-jun LI Zhong-si HE Ri-fei

. 2008, 8(3):  449-452. 

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A simulation device for investigating the behavior of current distribution was designed according to the structure characteristic of coke layer molten pool in manganese-silicon ferroalloy smelting arc furnace and similarity theory. NaCl solution with the specific conductance of 10.08~17.97 mS/cm and coke were used as the electric conduction phase to simulate the behavior of electric conduction in manganese-silicon submerged arc furnace. The current distribution relationship of the total current between coke layer and molten slag layer was measured in the molten pool. The results indicated that the relationships among the depth of coke layer, HC, the granularity of coke, DC, the conductivities of electric conduction phases (both in solid and liquid phases, rC and rL), the ratio of current through the bottom of molten pool Ib to total current It followed the following equation, i.e., Ib/It=4.36(rL/rC)1.523(DC/HC)0.186. When operational resistance of melting layer increased, Ib/It would decrease, which was in accordance with the actual process of manganese-silicon ferroalloy production.

反应与分离

Experimental Study on Flotation of Xinhua Rare Earths-bearing Phosphorite Ore

JIN Hui-xin WANG Hua LI Jun-qi MAO Xiao-hao ZHAO Ping-yuan

. 2008, 8(3):  453-459. 

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The effects of depressor kind and dosage, collector WF-01 dosage, flotation time, pulp concentration and particle size fraction of sample on P2O5 grade and recovery rate of concentrate from Xinhua rare earths-bearing phosphorite ore were investigated by reverse flotation technology. The rare earths of concentrate and tailings obtained in optimum flotation conditions were also analyzed. The results show that with WF-01 as the collector of dolomite minerals and other gangue minerals, industrial sulphuric acid is not suitable to be used singly as the depressor of phosphate minerals, while the better flotation result and enrichment of rare earths can be obtained when industrial phosphoric acid is used instead of industrial sulphuric acid. The optimum conditions obtained from the experiments are industrial phosphoric acid of 9 kg/t, WF-01 dosage of 0.8 kg/t, flotation time of 9 min, slurry concentration of 35% and particle size (-74 mm) fraction of 82%. In these conditions, P2O5 grade of concentrate can be increased from raw ore of 21.71% to more than 32% and P2O5 recovery rate comes up to 90%. The rare earths can be mainly enriched in concentrate by reverse flotation. The enrichment ratio of rare earths in concentration is 1.56 and the distribution proportion in concentrate is 87.09%.

Adsorption and Selective Catalytic Reduction Reactivity of NH3 to NOx over V2O5/AC Catalyst

XIAO Yong LIU Zhen-yu XING Xin-yan WANG Jian-cheng GUO Yan-xia HUANG Zhang-gen

. 2008, 8(3):  460-465. 

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A series of V2O5/AC catalysts were prepared by loading 2%(w) V2O5 on different activated cokes (AC) with pore volume impregnation method. NH3 response experiments and NH3 adsorption experiments were carried out to study the effects of surface texture, ash content, surface functional groups and V2O5 on NH3 adsorption and selective catalytic reduction (SCR) of NO at 200℃. The results show that NH3 adsorbed on V2O5 is very active for the SCR (the ratio of adsorbed NH3 to V2O5 loading is 1:5), the support AC and its ash component have low activities toward NH3 adsorption, the HNO3 treatment of AC results in the increase of oxygen and nitrogen contents in the AC and in NH3 adsorption on the AC (the amount of NH3 adsorbed in oxygen-containing and nitrogen-containing functional groups is 1.3 times of that adsorbed in V2O5), most of NH3 on the AC is not active for the SCR of NO, but part of it participates in the SCR reaction through migration to the V2O5 sites.

Adsorption Behavior and Mechanism of Pb2+ on Macroporous Chelating Resin

WANG Fei WANG Lian-jun LI Jian-sheng SUN Xiu-yun FAN Chen-xi

. 2008, 8(3):  466-471. 

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With the static and dynamic experiments, the adsorption behavior of Pb2+ on D418 resin was studied, and the adsorption process analyzed from the aspects of thermodynamics and kinetics, and the adsorption mechanism analyzed by infrared spectroscopy. The experimental results showed that in the studied condition range, the equilibrium adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption of Pb2+ on the resin was an endothermic process. Kinetic analysis showed that the adsorption rate was mainly governed by liquid film diffusion, with the increment of initial solution concentration, the adsorption rate would decrease. The static saturated adsorption capacity was 375 mg/g (based on resin) at 313 K, and the desorption rate could reach 97% by 3 mol/L nitric acid at 298 K. The optimal quantity of regenerant was five bed volumes. The resin can be used in wastewater treatment and enrichment of lead.

Separation of Methyl Isobutyl Ketone from Simulated Wastewater with Solvent Sublation

XIAO Bo CHANG Zhi-dong MA Yin-chen LIU Hui-zhou

. 2008, 8(3):  472-477. 

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Solvent sublation was applied to separate methyl isobutyl ketone (MIBK) from simulated wastewater containing MIBK at the concentration of 0.20%(j), which is of limited hydrophobic property and volatility. The effects of bubbling time, N2 flow rate, Vorg/Vaq ratio, concentration and type of co-solutes and surfactants on MIBK removal rate of solvent sublation were investigated, and the optimal results were obtained. The results show that the MIBK removal rate can be 25%~30% when the N2 flow rate is 40 mL/min, the Vorg/Vaq ratio 1:30, the concentration of NaCl 0.50%(w) and the concentration of ethanol 1.0%(j), while the positive effect of surfactants on the removal rate of solvent sublation is very limited, which varies from -10% to 5%.

Microfiltration of Sludge-containing Wastewater by Dynamic Membrane and Characteristics of Membrane Fouling

LI Jun XI Dan-li SHI Yong GAO Feng

. 2008, 8(3):  478-483. 

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The performance of kaolin dynamic membrane (DM) formed on ceramic membrane was studied in detail in treatment of sludge-containing wastewater. The effects of cross-flow rate, thansmembrane pressure and concentration of mixed liquid suspending solid (MLSS) on the flux and quality of fitrate were examined. The results indicated that the flux of filtrate increased with increase of cross-flow rate and transmembrane pressure, while increase of concentration of MLSS led to decrease of the flux. DM may be brushed off when cross-flow rate was greater than 2.0 m/s. Filtrate turbdity would be nearly zero in the first 30 min, and chemical oxygen demand removal would be 50% in an hour for the most part. The resistance of DM and held foulant accounted for 90% of the total filtration resistance. Based on analysis of the foulant attached on the DM surface, it was found that phosphorus and calcium were the main foulant elements, their mass contents were 23.77% and 20.60% respectively. Total organic carbon was about 4370 mg/m2, the main inorganic foulant elements calcium and magnesium were 1240 and 886 mg/m2 respectively in the fouled ceramic membrane through analysis of the extractant of fouled ceramic membrane. The flux of filtrate could restore to 85% of the clear ceramic membrane through chemical washing with 0.2 mol/L sodium hydroxide aqueous solution and 0.1 mol/L hydrogen chloride aqueous solution in series.

Synchronous Desulfurization and Denitrification of Gasoline by Porous Pillared Clay

HE Yan CHEN Ai-ping ZHANG Ying LIU Wei

. 2008, 8(3):  484-488. 

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Zr and Zr-Ce pillared clays were prepared using Ca-montmorillonite (Ca-MMT) as clay material by different methods. The intercalation solutions were prepared using ZrOCl2·8H2O and Ce(NO3)3 as precusors. Synchronous adsorptive desulfurization and denitrification of gasoline were investigated with the modified clays. The results show that clean gasoline with low sulfur and nitrogen could be produced. The intercalated clay was characterized by XRD, N2 adsorption-desorption and SEM analysis. And the structural model was proposed in pillared intercalation process. The XRD result shows that d001 of the modified clay is 2.38 nm, which is much larger than Ca-MMT of 1.54 nm. The specific surface area and specific pore volume of the pillared clays also increase obviously. The results show that the efficiencies of denitrification and desulfurization of the gasoline by the modified montmorillonite are 72.8% and 58.7% respectively.

Removal of Trace Sulfuric Acid Radical in Aqueous Solution with Foam Fractionation

SONG Wei-guang WU Zhao-liang LU Ke ZHENG Hui-jie

. 2008, 8(3):  489-493. 

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Separation of SO42- from simulated aqueous solution with the technology of foam fractionation was studied by using (1-hexadecyl)trimethyl ammonium hydroxide as the surfactant. The effects of pH, gas flow rate, surfactant dosage and volume of the solution on the separation were investigated. The experimental results showed that (1-hexadecyl)trimethyl ammonium hydroxide had good foam performance and removed SO42- effectively from aqueous solutions. Efficient separation of SO42- was achieved (enrichment ratio reached 22.4 and removal rate 94.1%) under the conditions of pH=10, gas flow rate 0.036 m3/h, surfactant dosage 0.13 g/L and volume of the solution 900 mL. In contrast with the commonly used cation surfactants, this technology would not introduce new acid radical ions in the aqueous solution by using (1-hexadecyl)trimethyl ammonium hydroxide, thus a new method was put forward for removing salts by foam fractionation.

Preparation of Trimethylammonium Anion Exchange Resin and Its Adsorption to Cr(VI)

LI Xiang WEI Rong-qing GAO Zhan LIU Xiao-ning

. 2008, 8(3):  494-498. 

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The trimethylammonium anion exchange resin was synthesized by the reaction of trimethylamine with chloracetylated polystyrene instead of chloromethylated polystyrene, and characterized by FT-IR spectrometry. Its microstructure and elements were also analyzed. The static adsorption properties of resin to Cr(VI) were studied. The results indicated that the adsorption increased with the decrease of pH and its highest adsorption capacity was 117 mg/g. The adsorption isotherms approximately fitted the Langmuir or Freundlich equation within the experimental range of concentrations, the correlative coefficients were 0.9988 and 0.9769. Besides, the kinetics of adsorption was mainly controlled by liquid film diffusion, and it fitted well into the Boyd liquid film diffusion model. The thermodynamic equilibrium functions were calculated, DG0<0, DH0=-3648.16 J/mol, DS0=3.98 J/(K×mol), so the anion exchange process was exothermic, spontaneous and entropy increasing. Using 5% NaOH nearly 96% Cr(VI) from the resin can be recovered.

Adsorption and Reduction of Cr(VI) in Aqueous Solution Using Steel Slag Particles

YANG Hui-fen FU Ping-feng ZHOU Feng

. 2008, 8(3):  499-503. 

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Steel slag particles, the solid waste produced from steelmaking industry, were used to directly remove toxic Cr(VI) in aqueous solution. The physical and chemical properties of steel slag particles were analyzed, and the process and mechanism of direct adsorption and reduction removal of Cr(VI) were studied in detail. The results showed that after 10 min stirring with grinded steel slag particles, the concentration of Cr(VI) was reduced from 200 to 0.5 mg/L, and reached national waste water discharge limits (GB8978-1996). The adsorption of Cr(VI) with steel slag particles followed the Langmuir isothermal adsorption with saturated adsorptive capacity of 6.878 mg/g. Chemical composition and XPS analysis showed that the adsorption of Cr(VI) using steel slag particles had two functions of adsorption and reduction. After adsorbing Cr(VI), the content of Cr(III) in steel slag particles increased from 0.0985% to 0.39%, and the content of FeO decreased from 9.20% to 8.35%. The Cr(OH)3 had covered on the steel slag particles surface adsorbed. The results revealed that the adsorbed Cr(VI) was reduced by reductive FeO to Cr3+ ion which was further deposited as Cr(OH)3 with lower toxicity. The Cr(OH)3 precipitation fixed on steel slag can be rapidly separated from water as steel slag particles deposit.

过程与工艺

Extraction Separation of Fe3+ in Acid Dissolving Solution of Sub-molten Salt Reaction Product from Ilmenite with Tributyl Phosphate and Preparation of Rutile TiO2

MA Bao-zhong WANG Li-na QI Tao FENG Yang CHU Jing-long ZHANG Yi

. 2008, 8(3):  504-510. 

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Extraction separation of ferric ions by solvent extraction method using tributyl phosphate (TBP) as extraction agent and sulfonic kerosene as thinner from the dissolved products of KOH and ilmenite in hydrochloric acid solution was studied. And TiO2 was prepared by hydrolyzing the raffinate. The effects of TBP concentration, hydrochloric acid concentration, concentration ratio of organic phase to aqueous phase (O/A) and extracting time on the extraction of ferric ions were investigated. The results showed that the extraction process was fast and the extraction rate of ferric ions increased with increasing the concentration of TBP and HCl concentration and decreasing the O/A ratio. The maximum extraction rate was larger than 99%. The reverse extraction rate using 1.0 mol/L NaCl solution reached 98%. The hydrolyzing product was rutile TiO2 spheres with the purity of more than 98%.

Co-production of Synthesis Gas and Zn with Na2CO3-K2CO3 Molten Salt Medium

AO Xian-quan WANG Hua WEI Yong-gang

. 2008, 8(3):  511-516. 

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For solving the conventional technological problems of methane conversion and metallic zinc production process, a novel molten salt reaction system was proposed. In this work, the reaction of zinc oxide with methane in a molten salt (Na2CO3/K2CO3 mass ratio is 1:1) medium was studied in a molten salt reactor with a gas chromatography (GC) analysis system. The GC analysis results of exhaust revealed that the gaseous components were H2, CO and CH4, and CO2 was not detected. Both the synthesis gas concentration and the ratio of H2 to CO (H2/CO) increased with increasing of reaction temperature, a H2/CO ratio of about 2 was achieved at 1198 K. Metallic zinc and synthesis gas were obtained separately from the gas phase and molten salt. After the reaction completed, the product of metallic zinc was successfully collected in the molten salt and characterized by XRD, SEM and EDS. Finally, analysis results of molten salt after reaction showed that there was a small amount of Na2O and NaOH by the XRD detection, which came from the faint reaction between methane and molten salt, thus the molten salt had a function of consuming carbon.

Effects of H2O and SO2 on Mn-Fe/MPS Catalyst for NO Reduction by NH3 at Lower Temperatures

HUANG Ji-hui TONG Hua TONG Zhi-quan ZHANG Jun-feng HUANG Yan

. 2008, 8(3):  517-522. 

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A catalyst of iron manganese oxides supported on mesoporous silica (MPS), Mn-Fe/MPS, was prepared and applied for selective catalytic reduction (SCR) of NO with ammonia in the presence of excessive oxygen at low temperatures. The effects of H2O and SO2 on the catalyst were studied. The results showed that a 99.1% NO conversion rate at 433 K at a space velocity of 20000 h-1 was achieved with the catalyst. H2O (10%, j) had not negative impact on the activity when the SCR reaction temperature was above 413 K and the NO SCR conversion rate could exceed 97.8%. A 97.2% NO conversion rate at 443 K in the presence of low concentration of SO2 (100′10-6) was obtained with the catalyst. In addition, as the SCR reaction proceeded in the presence of H2O and SO2, the catalyst was deactivated gradually, but its activity could almost be recovered to the initial level after heat treatment at 773 K, and the FT-IR spectra showed that the ammonium sulfate formed during SCR reaction in the presence of the H2O and SO2. Improving the SCR temperature could slow down the deactivation of catalyst. The effect of heat treatment temperature on the deactivated catalyst was also studied, and the recovery mechanism of the catalyst discussed. The prepared catalyst is substantially superior to any other reported catalysts in the literature in terms of integrated performance.

Synthesis of 2,6-Diisopropylnaphthalene with Isopropylation of Naphthalene in a Slurry Bubble Column Reactor

LI Ke-jing HE Guang-xiang JIN Hai-bo ZHAO Zhen

. 2008, 8(3):  523-528. 

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The isopropylation reaction of naphthalene in a slurry bubble column reactor was investigated by using Fe2(SO4)3/bentonite as catalyst. Fe2(SO4)3/bentonite solid acid catalyst was prepared and characterized by XRD, BET and FT-IR techniques. From the experimental results, the optimum reaction conditions were obtained as follows: superficial gas velocity was 1.1 cm/s, reaction temperature 240℃, mass concentration of catalyst 5.1%, reaction time 4 h, and pressure 0.8 MPa. Under these conditions, the conversion rate of naphthalene and yield of 2,6-DIPN were 77.7% and 8.6%, respectively. Meanwhile, the experimental results indicate that it is feasible to adopt slurry bubble column reactor for the isopropylation reaction of naphthalene.

Electrochemical Kinetics of Gold Dissolution in Alkaline Thiourea Solution

WANG Yun-yan CHAI Li-yuan

. 2008, 8(3):  529-534. 

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Electrochemical behavior and kinetics of gold dissolution in alkaline thiourea solution have been investigated by electrochemical techniques. The results indicate that open circuit potential moves negatively from -130 mV to -280 mV and the time for reaching stable state changes from 400 s to 800 s when the concentration of thiourea increases from 0 to 0.2 mol/L. The anodic current peak at cyclic voltammetric curves represents oxidation of gold, current increasing rapidly after 850 mV results from the evolution of oxygen when scanning positively, while the cathodic reduction peak at 220 mV is the reduction of gold-thiourea complex ion when scanning negatively. The peak potential of anodic oxidation moves negatively for 30 mV with the addition of thiourea, and peak current is raised 15.5 times. Anodic peak potential and current change from 655 mV down to 480 mV and from 1.985 mA down to 0.09528 mA, respectively when the concentration of thiourea increases from 0.05 mol/L to 0.20 mol/L. Anodic dissolution of gold becomes easier when improving pH value of solution. The peak current increases from 0.761 mA to 4.387 mA sharply and peak potential decreases from 655 mV to 596 mV when temperature rises from 25℃ to 35℃. However, too high temperature will result in the decomposition of thiourea, so room temperature is optimal. Theoretical analysis illustrates that anodic dissolution of gold is an irreversible electron transfer reaction.

A New Process of Low-temperature Chlorination of Chalcopyrite Concentrate without Environmental Contamination

FU Nian-xin 岩崎巌 玉川建雄 小林幹男

. 2008, 8(3):  535-539. 

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A low-temperature chlorination process of chalcopyrite concentrate was studied using a small fluidized bed reactor. The effects of Cl2 supply, temperature and particle size of the concentrate on the chlorination behavior, fluidization condition and reaction products were investigated. The results show that proper excess of Cl2 supply is necessary for full chlorination of the concentrate. The Cl2 concentration in effluent gases should not be beyond 0.015% in order to prevent the formation of more S2Cl2 and the vaporization of FeCl3. The increase in reaction temperature can effectively reduce the sulfur contents in the products, decreasing to 2%~3% at an appropriate temperature of 270℃. The sticking of the particles is due to the fritting of a low-melting-point eutectic mixture at high temperature. The particles with larger sizes (147~208 mm) are favorable for the fluidized bed to be in a steady-state fluidization state. The exhaust chlorine and S2Cl2 from the lower reactor are expended for the chlorination of the concentrate in the upper one in the two-stage chlorination experiment. The fully chlorinated products with an average 2.8% sulfur content can be obtained, and the system can continuously run smoothly under the optimized operating conditions (at 270℃ of the lower reactor temperature and within 0.015% of Cl2 concentration in the effluent gases, and at 250~270℃ of the upper reactor temperature).

Synthesis and Characterization of Poly(N-vinylcaprolactam)

ZHANG Qiang YIN De-hong FAN Shuan-shi WANG Jin-qu

. 2008, 8(3):  540-544. 

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Poly(N-vinylcaprolactam) (PVCL) was synthesized by free-radical bulk polymerization in aqueous solution with azodiisobutyronitrile (AIBN) as initiator and N-vinylcaprolactam (VCL) as reactants. The effects of initiator and solvent dosages, reaction time and reaction temperature on polymerization of the polymer were studied. The reaction mechanism of PVCL synthesized in aqueous solution was analysed. Under the optimum reaction conditions of mass ratio of VCL:AIBN:H2O=1:0.05:15, reacting for 5 h at 75℃, the most yield of PVCL was 97%. The average molecular weight of the polymer was evaluated with gel permeation chromatography (GPC). Its structure was analyzed by infrared spectrometry (FT-IR) and nuclear magnetic resonance spectroscopy (1HNMR). The low critical solution temperature was 32℃, which was measured by spectrophotometer.

Synthesis of N,N'-Diphenylurea from Urea and Aniline under Atmospheric Pressure without Catalyst

YOU Zhi-min PEI Yi-xia LI Hui-quan DAI You-zhi ZHANG Yi

. 2008, 8(3):  545-549. 

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The synthesis of N,N'-diphenylurea (DPU) from urea and aniline under atmospheric pressure without any catalyst and additional solvent was studied. The effects of reaction conditions and process intensification techniques on the yields of product DPU were investigated. Combining use of nitrogen gas flowing during reaction and vacuum evaporating after reaction, the yield of DPU reached 99.1% under optimum reaction conditions (reaction temperature 180℃, molar ratio of aniline/urea 5 and reaction time 1.5 h). The unreacted aniline could be recycled and reused. In addition, the reaction mechanism was also studied by means of HPLC analysis and proving experiment, it is ascertained that phenylurea is the major intermediate in the reaction.

The Effects of Outer Influential Factors on Hydrogen Peroxide Synthesis in an Alkaline Fuel Cell Reactor

XU Yuan SONG Tian-shun XU Fu-yuan CHEN Ying-wen SHEN Shu-bao

. 2008, 8(3):  550-554. 

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The generation process of hydrogen peroxide in a fuel cell reactor was studied, in which continuously injected KOH aqueous solution was used as electrolyte. The results showed that the cell current, H2O2 concentration and current efficiency were affected by the concentration of KOH aqueous solution and flow rates of H2O, KOH, O2 and H2. When the concentration of KOH was 2 mol/L, the flow rates of H2O, KOH, H2 and O2 were 80 mL/h, 150 mL/h, 20 mL/min and 60 mL/min respectively, high H2O2 productivity (0.225 mol/L) and current efficiency (almost 100%) were obtained from the reactor system, which is expected to be applicable in wastewater treatment.

生化工程专栏

Mutagensis of Strain Klebsiella pneumoniae Producing 1,3-Propanediol by Cold Plasma at Atmospheric Pressure

DONG Xiao-yu LI Shuang HOU Ying-min XIU Zhi-long

. 2008, 8(3):  555-560. 

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An efficient agar plate mutagensis and screening technique for improving mutation frequency and simplifying operation was established by using dielectric barrier discharge plasma. Klebsiella pneumoniae producing 1,3-propanediol (1,3-PD) was used as a model strain. A positive mutant strain (K. 81206) was selected, which can endure a high concentration of glycerol, and produce high concentration of 1,3-PD. The results of batch fermentation by K. 81206 showed that the yield of 1,3-PD from glycerol was increased by 23% and the maximum specific growth rate was increased by 18% at logarithmic phase, respectively, compared with control strain. The fed-batch fermentation showed that the 1,3-PD concentration increased to 70.5 g/L and yield of 1,3-PD from glycerol was 0.57 g/g, which means 47% and 58% increase compared with the wild strain, respectively. These results demonstrated that the agar plate mutagensis and screening technique would be useful in the industrial biological production of 1,3-PD as well as other chemicals produced by industrial microorganisms.

Fermentation Modes of Saccharomyces cerevisiae HYS98 for High Productivity of S-adenosyl-L-methionine

SHEN Jian LI Yuan-guang SHEN Guo-min YANG Dong

. 2008, 8(3):  561-566. 

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The metabolic characteristics under four operation ways of batch fermentation, constant feeding rate fermentation, changing feeding rate fermentation and batch feeding fermentation, were studied in a 5 L fermentator. And the influences of different S-adenosyl-L-methionine (SAM) fermentation modes were investigated. The optimum fermentation mode among them of Saccharomyces cerevisiae HYS98 was batch feeding. The average productivity and cell growth rate of the feed batch fermentation were obtained as 0.123 g/(L×h) and 1.030 g/(L×h), which were 68% and 73% higher than the highest levels reported in the literature respectively. The results laid the foundations for further optimization of SAM fermentation process.

An Immobilized Lipase with High Enantioselectivity in the Resolution of Racemic Ibuprofen

TANG Liang-hua XIA Li-ming SU Min GUO Hua-ying ZHANG Jie-ping

. 2008, 8(3):  567-571. 

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In order to resolute racemic ibuprofen more effectively in organic solvent, a new method for the immobilization of Penicillium expansum lipase in macroporous resin AB-8 was established. The lipase, PEL, immobilized in macroporous resin AB-8 exhibited higher activity and enatioselectivity than others. The resolution of (R,S)-ibuprofen was performed in microaqueous media by PEL immobilized in macroporous resin AB-8. It was found that medium type, "memorial" pH value and water content were of great effects on the resolution of racemic ibuprofen, and the conversion rate of the reaction catalyzed by the lipase immobilized in macroporous resin AB-8 reached 47% with excellent eep (98.75%) in isooctane without water at "memorial" pH 9.0, 40℃ for 30 h. Immobilization by this method affected the enzymatic properties of PEL in nonaqueous reaction media. The immobilized PEL was then not easy to agglomerate in nonaqueous media. And its activity in the resolution reaction was enhanced accordingly. The immobilized lipase in the resolution reaction was stable and could be well maintained. And the conversion rate of the reaction catalyzed by immobilized PEL reached 47% and the eep was more than 98% with excellent enantioselectivity when the enzymatic resolution reached equilibrium after 30 h. So PEL immobilized in macroporous resin AB-8 had a potential use in the resolution of ibuprofen.

Synthesis of Glucuronic Acid by Pd/La0.5Pb0.5MnO3 Catalytic Oxidation from Methyl Glucoside

YUAN Hua SUN Yan-bin WU Mao DU Zhi-ping YAN Zhi-guo WU Yuan-xin

. 2008, 8(3):  572-575. 

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Glucuronic acid was synthesized by 1% Pd/La0.5Pb0.5MnO3 catalytic oxidation from methyl glucoside oxidized selectively. The support and catalyst samples were characterized by XRD and SEM techniques. The effects of different catalyst preparation methods and conditions of catalytic oxidation on the yield of glucuronic acid were studied. The results showed that the supports produced by sol-gel method and the catalyst prepared by precipitation had better catalytic activity, the yield of glucuronic acid reached 29.5% under the conditions of catalyst dosage 1/6 (based on glucoside mass), temperature 70℃, pH value 9, reaction time 5 h, and the ordinary pressure, and the catalyst had good selectivity.

材料工程专栏

Preparation of Humic Acid Resin/Silica Composite Material and Its Adsorption Ability to Heavy Metal Ions

SHANG Yu LIU Hai-di WANG Hai-zeng

. 2008, 8(3):  576-582. 

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Humic acid resin/silica composite was prepared using acidizing and co-precipitating method, with humic acid and water glass as raw materials. The material samples were characterized by means of thermogravimetry, BET specific surface area measurement, Fourier transformation infrared spectroscopy and scanning electron microscope. Adsorption of Cd(II), Cu(II), Ni(II) and Pb(II) was studied in batch tests, and adsorption isotherms were determined in order to evaluate the adsorbing ability of the materials. The results revealed that the specific surface area of the composite material increased with the doping of silicon dioxide, and the stability of composite material in water was improved. Its adsorption mechanisms mainly included ion exchange and complexation or chelation. Langmuir and Freundlich models were applied to examine the data. The experimental results showed that the saturated adsorption amount of Pb2+ on humic acid resin/silica composite material was 262.5 mg/g, that of Cd2+ 43.55 mg/g, that of Ni2+ 23.58 mg/g, and that of Cu2+ 45.54 mg/g. The equilibrium adsorption was found to fit the Langmuir adsorption isotherm.

Preparation of Magnetic Silica Nanoparticles and Their Application in Laccase Immobilization

LIU Yu GUO Chen WANG Feng LIU Chun-zhao LIU Hui-zhou

. 2008, 8(3):  583-588. 

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Laccase was immobilized on the silanized magnetic silica nanoparticles by using glutaradehyde as the cross-linker. Immobilization of laccase was investigated and its immobilizing conditions were optimized. The results were achieved with the concentration of 8% glutaradehyde, immobilizing time of 6 h, the buffer of pH 7.0 and initial laccase concentration of 0.15 g/L. The optimum pH and temperature of immobilized laccase were 4.0 and 20℃, respectively. After the immobilized enzyme was kept at 60℃ for 4 h, it remained 60.9% of its initial activity. The immobilized laccase could retain above 55% of activity after 10 consecutive operations. The experimental results showed that the thermal stability and operational stability of immobilized laccase were improved in comparison with free laccase.

Preparation and Characterization of SiC Thin Film on Cordierite with Chemical Vapor Deposition

YIN Bo-wen YANG Yan MA Bing ZHANG Wei-gang

. 2008, 8(3):  589-594. 

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Thin film of SiC on porous cordierite was prepared from CH3SiCl3-H2 and SiCl4-CH4-H2 gaseous sources by isothermal and isobaric chemical vapor deposition (CVD) at the temperatures of 1100 and 1000℃ and ambient pressure. The as-deposited thin film was characterized with scanning electron microscopy, X-ray diffraction, Raman micro-spectrum, high-resolution transmission electron microscopy and EDAX elementary analysis. The results indicated that the surface morphology of SiC thin film deposited from CH3SiCl3-H2 source showed pyramid structure which was significantly different from that from SiCl4-CH4-H2 source. Pyramid structure revealed that (111) plane of b-SiC was the preferred orientation in the XRD pattern. In most cases, the average size of pyramid shaped particles deposited from CH3SiCl3-H2 source was bigger than that from SiCl4-CH4-H2. The thin film deposited from CH3SiCl3-H2 source consisted of pure b-SiC phase, and its Si content increased with decreasing temperature. However, the SiC film from SiCl4-CH4-H2 source was amorphous carbon-doped SiC. Its C content increased with decreasing temperature. Additionally, sheet resistance of the SiC film from CH3SiCl3-H2 source was above a kW scale, increasing with temperature decreasing, while that from SiCl4-CH4-H2 source decreased rapidly with decreasing temperature. Sheet resistance of the SiC film deposited at 1100℃ from SiCl4-CH4-H2 source was above a kW scale, falling to a W scale at 1000℃.

In situ Preparation and Drug Release Properties of Validamycin-loaded Silica Hollow Microcapsules

LIANG Xu-dong LI Xue-guang FU Yao WEN Li-xiong CHEN Jian-feng

. 2008, 8(3):  595-598. 

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Validamycin-loaded silica hollow microspheres were prepared by in situ hydrolysis of tetraethyl orthosilicate (TEOS) in Water-Oil (W/O) emulsions. The microspheres were characterized by SEM, XRD, FT-IR and particle size distribution. The results indicated that the drug-loaded microspheres had an amorphous hollow spherical structure with the diameters of 7.5~15 mm. The amount of validamycin entrapped in the microspheres was about 31.9%(w). Sustained-releasing studies showed that the release time was about 240 min and more than 90% of the loaded drug in the microspheres was delivered, indicating good sustained release behavior of the drug-loaded microspheres.

Preparation and Pervaporation Performance of Silicalite-1 Zeolite Membrane with a Two-stage Temperature-varied Hydrothermal Technique

SUN Wei-guo YANG Jian-hua WANG Ai-fang WANG Jin-qu HAN Hui-lin LU Jin-ming

. 2008, 8(3):  599-602. 

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A two-stage temperature-varied hydrothermal technique was adopted to synthesize Silicalite-1 zeolite membrane supported on the porous stainless steel tube for pervaporation separation of ethanol from water. The effects of crystallization temperature and synthesis time on the pervaporation performance of the membrane were investigated with the synthesis solution composition specified in this work. The prepared membrane was characterized by XRD, SEM and single gas permeation tests. The result showed that a membrane with a flux of 1.25 kg/(m2×h) and separation factor of 36.2 at the ethanol content of 4.8%(w) and 60℃ could be obtained only through one time synthesis when the H2O/Si ratio in molar was 80 and the second stage crystallization temperature was high at 165℃. Instead, a flux of 2.8 kg/(m2×h) same as the highest one reported in the literature with separation factor of 34.3 at the same separation condition was obtained using the Silicalite-1 membrane through twice synthesis when H2O/Si ratio was 225 and the second stage crystallization temperature low at 150℃.

Synthesis and Property Characterization of Submicron LiCu0.1Mn1.9O3.9F0.1 Electrode Material for Lithium-ion Batteries

LIU Chang-jiu LI Guang-yan YI Ling-ying ZHAO Wei-min

. 2008, 8(3):  603-606. 

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F- and Cu2+ co-doped LiCu0.1Mn1.9O3.9F0.1 was prepared with sol-gel method. XRD and SEM analysis demonstrated that the sample had perfect spinel type structure, and the sizes of particles were up to submicron level with homogenous distribution. Electrochemical tests showed that the doping of F- and Cu2+ decreased the charge transfer resistance. The discharge capacity for the LiCu0.1Mn1.9O3.9F0.1 was 112 mA×h/g. In particular, the discharge capacity retention was 89.1% after 50 charge-discharge cycles, suggesting the good structural stability and electrochemical properties of the prepared samples. In addition, the mechanism of improvement for co-doped LiCu0.1Mn1.9O3.9F0.1 was also discussed.

综述

Recent Research Progress in Biogas Fermentation Process

CHENG Xi-yu ZHUANG Guo-qiang SU Zhi-guo LIU Chun-zhao

. 2008, 8(3):  607-615. 

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This review summarized recent research progress in the field of biogas fermentation process including microbial community regulation, process optimization and control, as well as fermentation system designing, and then pointed out that the process instability and low productivity of biogas fermentation is due to lack of enough understanding on the mechanism of anaerobic digestion process. The tendency of research and development in biogas engineering in the near future was also put forward in the following areas for enhancing biogas productivity: metagenomics of microbial community and metabolic network, multi-scale process control, pretreatment and compatibility of waste materials, and co-production of both hydrogen and methane.

Microscale and Nanoscale Process Systems Engineering: Challenge and Progress

YANG You-qi

. 2008, 8(3):  616-624. 

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This is an overview of the development of process systems engineering (PSE) in a smaller world. Two different spatio-temporal scopes are identified for microscale and nanoscale process systems. The features and challenges for each scale are reviewed, and different methodologies used by them discussed. Comparison of these two new areas with traditional process systems engineering is described. If microscale PSE could be considered as an extension of traditional PSE, nanoscale PSE should be accepted as a new discipline which has looser connection with the extant core of chemical engineering. Since "molecular factories" is the next frontier of processing scale, nanoscale PSE will be the new theory to handle the design, simulation and operation of those active processing systems.