Table of Content

20 August 2012, Volume 12 Issue 4

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流动与传递

CFD Simulation of Gas-Liquid Flow in an Internal Loop Airlift Reactor with Different Draft Tubes

LIAN Yi-cheng JIN Hai-bo;

. 2012, 12(4):  541-549. 

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An internal loop airlift reactor (ILAR) (1240 mm height, 165 mm diameter) with draft tube (590 m in height) has been simulated using computational fluid dynamics with Euler-Euler model. The effects of draft tube (diameter and bottom gap height) on gas holdup and water velocity are studied. The results show that superficial gas velocity, draft tube diameter and bottom gap height of draft tube have a great effect on gas holdup and water superficial velocity, especially in the downcomer of ILAR. With increasing of superficial gas velocity, the gas holdup in ILAR is increased. When the internal diameter ratio of draft tube to reactor, Dt/D, is 0.58, the gas-liquid circulation is the easiest to come out. But the gas holdup and gas-liquid velocity are low, when the bottom height of draft tube is 30 mm. Moreover, with the tongue angle of gas-liquid separator is increased, the gas holdup in the downcomer is increased. However, when the tongue angle is 45o, the gas-liquid velocity is the largest.

Influence of EMBr on Flow Field of Molten Steel in a Continuous Casting Slab Mold

JIA Hao ZHANG Zhen-qiang CHANG Tong-xu DENG Kang REN Zhong-ming;

. 2012, 12(4):  550-557. 

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A mercury model was developed to studied the effects of different types of electromagnetic brake (EMBr), electromagnetic mold brake ruler (EMBr-Ruler) and flow control mold (FC Mold) on molten steel flow with the practical casting speeds of 1.0, 1.3 and 2.0 m/min in a slab continuous casting mold. The results show that the velocity and fluctuation of the liquid surface flow are depressed with FC Mold, the maximum values of the horizontal velocity and turbulent intensity near the surface are 1/5 and 1/6 respectively compared with those without EMBr, both types of EMBr compress the expanding space of the jet discharged from the outport, the maximum vertical velocity of downward flow near the narrow wall increases from 0.030 m/s without EMBr to 0.066 (EMBr-Ruler) and 0.057 m/s (FC Mold), it inhibits the formation of plug flow. EMBr is conductive to the formation of plug flow when the port is placed in the EMBr region and the casting speed is suitable. The flow velocity distribution in mold with FC Mold is better than that without EMBr and with EMBr-Ruler with high practical casting speed (2 m/min). The flow field is better with EMBr-Ruler at 1.3 m/min, but when the casting speed is low (1 m/min), the effects of two types of EMBr are unsatisfactory, even deteriorate the original metal flow.

Hydrodynamic Performance of Fluidized Bed with Vertical Sieve Tray

DONG Qun JIA Zhao WANG Shu-yan

. 2012, 12(4):  558-563. 

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Gas-solid fluidization of the vertical sieve tray as fluidized bed internals was carried out experimentally using FCC catalyst. The effects of gas velocity in tray hole, circulation rate of solid, opening ratio of the caps and other sieve tray structures on pressure drop and elevated quantity of fluidized bed are studied. The results show that the vertical sieve tray fluidized bed makes possible high speed bubbleless jet co-flow at air velocity of 4 m/s within the caps for the gas-solid countercurrent flow mode, leading to a desirable gas solid contact, reduced back-mixing, fast fluidization and small fluctuation due to no bubbles in bed. Pressure drop of the bed rises with the increase of gas velocity in tray hole, and decreases with the rise of opening fraction of the cap and diameter of tray hole. A great rate of solids lift will lead to a high pressure drop of the bed. The rate of solids lift rises with the increase of gas velocity in tray hole, height of bottom clearance and circulation rate of solids, and decreases with the rise of height of the cap and tower section. The rate of solids lift is maximized at an intermediate diameter of tray hole. When the opening fraction is from 1.2 to 2.5, tray hole area/cap sectional area 0.42, and bottom clearance height/tray hole diameter between 0.36 and 0.64, excellent hydrodynamic performance can be reached.

Preparation and Rheology of Coal Water Slurry Blended with Blast Furnace Sludge

GAO Zhi-fang LI Liao-sha WU Zhao-jun WU Xing-rong SU Shi-huai WU Xiao-hua

. 2012, 12(4):  564-568. 

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Blast furnace sludge (BFS) from Ma￠anshan Iron and Steel Co., Ltd. was added in Dongkai fat coal to prepare coal water slurry. Based on the analysis of physicochemical properties of BFS and fat coal, the apparent viscosity, concentration, caloric value of coal water slurry with addition of BFS were examined, and the effect of BFS was analyzed by regression method. The results show that the viscosity of coal water slurry is decreased and its slurrying ability enhanced with the increase of BFS addition, whereas, the slurrying stability and caloric value are decreased. The main mechanism is that lots of alkaline oxides in BFS lead to soluble ion dissolution with changing of the pH value of coal water slurry. The relative content of soluble and insoluble minerals, which affect the density of coal, is also a key factor for the slurrying ability. When the addition of BFS is 24%, the slurrying ability and caloric value of coal water slurry can meet industrial requirements.

反应与分离

Extraction of Phenol with Primary Amine N1923

YANG De-ling NING Peng-ge CAO Hong-bin WANG Shao-na

. 2012, 12(4):  569-575. 

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The extraction of phenol by primary amine N1923 in various diluents (sulfonated kerosene, petroleum ether, toluene or n-octanol) were studied at 25℃. As a result, 40%(j) amine N1923 diluted in toluene was more efficient than other systems. With this selected extractant, the effects of initial concentration of phenol, equilibrium pH value (pHeq), temperature and salting-out agent on the equilibrium distribution coefficient (D) were examined. The results showed that pHeq had little effect on D at pHeq<8.3. However, a great impact of the salts on D was observed, the order was (NH4)2SO4>NaCl>NH4Cl. The ratio of N1923 to phenol in the extracted complex was considered as 1:1 using the slope method. Moreover, Extraction equilibrium constant, reaction enthalpy DrHmQ, Gibbs free energy DrGmQ and entropy change DrSmQ were calculated. The solvent recycle experiments showed that the extraction yield of phenol was reduced gradually, which was due to the solubility of anmine N1923 in water. Multistage cross-current extraction simulation of industrial gasification wastewater was carried out using the selected system. Over 99% of phenol was removed after one stage extraction and the concentration of phenol in raffinate of three-stage extraction was close to the wastewater discharge standard of China (GB 8978-1996).

Recovery of Vanadium and Aluminum in Ferrovanadium Slag from Thermite Method by Sodium Carbonate-roasting

GAO Ming-lei CHEN Dong-hui SHI Li-xin LI Lan-jie ZHOU Bing-jing QI Jian

. 2012, 12(4):  576-582. 

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By mineralogical analysis, thermodynamic calculation, and comparative experiments, the synchronous conversion of vanadium and aluminum was studied, and dissolving mechanism in the process of sodium carbonate roasting and water leaching on ferrovanadium slag. The results showed that magnesia-alumina spinel (MgO×Al2O3) and CaO×2Al2O3 phases gradually disappeared, and MgO phase, alkali melting phase of Na2O×Al2O3 and phase vanadate were generated in the roasting process. Na2O×Al2O3 and vanadate phases increased obviously with the increase of roasting temperature and time, resulting in the dissolution increase of vanadium and aluminum. Vanadium and aluminum, in vanadate and sodium aluminate, could be dissolved into water solution, as the solution was alkaline when the clinker was leached by water. The solid residues were a small amount of unreacted magnesia-alumina spinel and new generated MgO and Ca(OH)2. The optimum roasting conditions were obtained as follows: grinding particle size below 75 mm, molar ratio of Al2O3 and V2O5 to Na2CO3 1:1, roasting temperature 1000℃ and roasting time 4 h. Under these conditions, the leaching rates of vanadium and aluminum were up to 90% and 75%, respectively.

Preparation of Poly(1,1,3,3-tetramethylguanidine acrylate) and Its Absorption-Desorption Properties to SO2

XIA Yu-zheng DU Shi-mao WEI Jia-ming LIU Jun LI Jian-zhou SHI Shu-xian

. 2012, 12(4):  583-589. 

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The polyacrylic acid with different molecular weights was synthesized by free radical solution polymerization, then the poly(1,1,3,3-tetramethylguandium acrylate) (PTMGA) was obtained through neutralizing PAA with 1,1,3,3-tetramethylguanidine. The effects of temperatures and concentration of flue gas on absorption and desorption properties of SO2 by PTMGA solution were investigated in the current industrial processes. The results show that the title PTMGA solution is a kind of good absorption-desorption and selective absorption agent to SO2. The absorption efficiency of PTMGA aqueous solution is higher than 97%, and the desorption efficiency more than 40% when temperature is 40℃, and SO2 concentration of flue gas 2% or 4%(j). Furthermore, the PTMGA solution tends to absorb SO2 at low temperature, and desorb SO2 at high temperature.

Adsorption Kinetics of Friedel's Salt for Removal of Cd2+ from Low Concentration Wastewater

ZHANG Juan-juan ZHAO He CAO Hong-bin LI Zhi-bao

. 2012, 12(4):  590-595. 

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The kinetics and adsorption isotherms of Cd2+ removal from wastewater with Friedel's salt (FS, 3CaO×A12O3×CaCl2×10H2O), as adsorbent were investigated. The influences of FS dosage, temperature and initial Cd2+ concentration were examined. The results showed that the removal rate of Cd2+ from initial concentration (10 mg/L) wastewater was up to 94.34% with the adsorption capacity of 301.9 mg/g when FS dosage was 0.03 g/L. The basic adsorption mechanism was ion exchange. Finally, Cd2+ in the water existed in the form of complexes as Cd4Al2(OH)12Cl2(H2O)4×xH2O and Cd4Al2(OH)12Cl2×4H2O. Pseudo-?rst-order model was applied to correlate adsorption reaction data, adsorption rate constant k was obtained with the value of 0.049 min-1. The Langmuir isotherm equation suitably fitted to the adsorption isotherm data.

Electric Demulsification Dehydration of Crude Oil Added with Aging Oil from Zhongyuan Oilfield

LI Rui-feng CHEN Jia-qing LI Feng-chun LIU Wen HUANG Song-tao LIU Peng

. 2012, 12(4):  596-601. 

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Based on self-developed high-voltage/high-frequency pulse AC power and high-voltage/industrial frequency power, the comparison experiments were carried out with the aging oil and ordinary crude oil from Zhongyuan oilfield to study the dehydration performance, and the impacts of frequency, voltage, aging oil content, water content on demulsification efficiency were examined. The results showed that increasing the frequency appropriately was conducive to aging oil demulsification, compared with 500 Hz, the dehydration efficiency of electric field of 1500 Hz was improved by 10.3% averagely, the maximum was 35.0%, the result of high frequency was much better than industrial frequency. Increasing the intensity of electric field appropriately was also conducive to aging oil demulsification, compared with 1 kV, the dehydration efficiency of electric field of 4 kV was improved by 40.6% averagely, the maximum was 81.1%.

Reaction Kinetics for Preparation of Methacrolein by Condensation of Formaldehyde with Propionaldehyde

LI Yu-chao YAN Rui-yi WANG Lei DIAO Yanyan

. 2012, 12(4):  602-607. 

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A series of second amines were used to catalyze the synthesis of methacrolein from formaldehyde and propionaldehyde via Mannich reaction. By using diethylamine, the highest yield of 94% was obtained. The kinetic model was obtained by analysis of the reaction process. The parameters in the model were determined: reaction order 2.456, activation energy 62.45 kJ/mol and frequency factor 8.182′107 (mol/L)-1.456/s. In situ FT-IR spectroscopy was introduced to monitor the concentration of compounds in real time during the reaction. The samples taken in different reaction times were analyzed by GC-MS, and the intermediate Mannich base was detected, laying a foundation for the reaction mechanism.

Non-isothermal Decomposition Kinetics of Methyl N-Phenyl Carbamate for Preparation of Phenyl Isocyanate

ZHU Gan-yu TANG Qing; WU Hui-xiong CAO Yan LIU Hai-tao; LI Xin-tao ZHANG Qin-hua LI Hui-quan;

. 2012, 12(4):  608-612. 

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The decomposition process of methyl N-phenyl carbamate (MPC) was studied by TG-DTG, DSC and IR techniques. It is shown that the decomposition of MPC for generating phenyl isocyanate (PI) is one step with the generation of methanol gas. Then non-isothermal decomposition kinetics of MPC was studied. Flynn-Wall-Ozawa method was used to calculate the reaction activation energy, E, through the data of DSC/TG/DTG. The kinetic parameters were calculated using five kinetic analytical methods. The result indicated that the mechanism function of MPC decomposition was G(a)=a1/3, E and the pre-exponential factor, A, of the reaction were E=20.52 kJ/mol and lgA=2.23, respectively, and the kinetic equation could be expressed as a1/3=169.82exp[20.52′103/(8.314T)]t.

Leaching Behaviors of Aluminum and Silicon Compounds in Aluminum-rich Fly Ash in Dilute Alkaline Solution

BO Chun-li ZHENG Shi-li MA Shu-hua XIE Hua

. 2012, 12(4):  613-617. 

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The leaching behaviors of aluminum and silicon compounds in aluminum-rich fly ash generated in circulating fluidized bed in dilute alkaline solution were studied. The physical and chemical properties of the ash were determined. And the effects of alkaline concentration, reaction temperature and reaction time on performances of silica and alumina were investigated. The results show that the ash is composed of various irregular porous particulates which are more active. Alumina and silica in the ash behave quite differently in a mild process occurred in alkaline dissolution. On the conditions of reaction temperature 95℃, NaOH concentration 150 g/L and reaction time 90 min, there is a biggest difference between the performance of alumina and silica in the ash. The mass ratio of Al2O3 to SiO2 in the ash can be raised from 0.78 to 0.99, with extraction rate of SiO2 and Al2O3 reaching the levels of 23.15% and 1.68% respectively.

过程与工艺

Non-isothermal Analysis on the Evaporation Behavior of CaF2-SiO2-CaO System Slag

JU Jian-tao LV Zhen-lin LIAO Zhi-yuan ZHAO Jun-xue

. 2012, 12(4):  618-624. 

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The weight loss rate of CaF2-SiO2-CaO system was measured by a simultaneous thermal analyzer and platinic crucible at the heating rate of 10 K/min, and the thermal volatile kinetics studied using a non-isothermal approach. The conversion function f(a) and volatile kinetic parameters of slag were determined by the TG curves, kinetics model established verified, and its evaporation mechanism analyzed. The results indicated that the weight loss rate was closely related to the liquidus and phase of slag. But the volatility had no significant correlation with basicity. The evaporation causing the change composition of slag could be divided into two stages in 1373~1573 and 1573~1773 K. The former belonged to three-dimensional diffusion with differential form f(a)=3/2(1-a)4/3[(1-a)-1/3-1]-1, the latter to random nucleation and growth with differential form f(a)=1/4(1-a)[-ln(1-a)]-3. For the 70%CaF2-30%SiO2 slag system, the activation energy at two stages was 550.10 and 376.16 kJ/mol, and the frequency factor lgA 16.55 and 8.4, respectively. The experimental results were in good agreement with the kinetic model.

Solubility Measurement of Calcium Sulfate Dihydrate in NH4Cl-(NH4)2SO4 Solutions

TIAN Ping NING Peng-ge CAO Hong-bin LI Zhi-bao

. 2012, 12(4):  625-630. 

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The solubility of CaSO4×2H2O in the solution of NH4Cl and mixed solution of NH4Cl-(NH4)2SO4 was studied using dissolution method in a temperature range from 298.15 to 343.15 K. The results showed that in the two solutions the solubility of CaSO4×2H2O increased with increasing of NH4Cl concentration, but the temperature had little effect. In addition, a mixed electrolyte NRTL model was employed to calculate the solubility of CaSO4×2H2O in different concentrations of NH4Cl at various temperatures. New model parameters for electrolyte NRTL model were obtained via regression of experimental data. The calculated solubility was in good agreement with experimental values with the relative average deviation of 2.36%.

Crystallization Properties of Schoenite in Ethanol-Water and Methanol-Water Mixed Solvents

YUAN Jun-sheng HAN Rong-min LIU Yan-lan GUO Xiao-fu

. 2012, 12(4):  631-635. 

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Using wet slag method, the solubilities of schoenite in ethanol-water and methanol-water systems were determined. With conductivity method, the metastable zone widths of schoenite were measured, and the influences of temperature, cooling rate and agitating rate on it also investigated. The results show that the higher proportion the ethanol or methanol in the mixed solvents, the smaller solubility the schoenite has. When the volume ratio of methanol or ethanol to water is 1:1, the solubility of schoenite nearly reach zero. Moreover, the crystalline area of K2SO4 in methanol-water solvent is bigger than that in ethanol-water solvent under the same solvent ratio. Under the present experimental conditions, the metastable zone width of schoenite is expanded from 0.40% to 1.48% with the cooling rate increasing from 15 to 35℃/h, decreasing from 1.54% to 1.04% along with the stirring rate increasing from 250 to 460 r/min, and changing from 1.61% to 1.24% when the temperature rises from 25℃ to 35℃.

Process Optimization of the Carbonization of Sodium Chromate for Sodium Dichromate

QU Jing-kui ZHOU En-nian GUO Wei YU Zhi-hui QI Tao

. 2012, 12(4):  636-640. 

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The effects of reaction temperature, pressure of CO2, stirring speed, reaction time and concentration of feed liquid on the first carbonization rate in the process of carbonization for sodium dichromate were studied, and the influences of the first carbonation rate and total concentration of chromium on the secondary carbonation rate. The experiment was carried in a high pressure reaction kettle. The results showed that when the reaction temperature was 60℃, pressure of CO2 1.2 MPa, stirring speed 800 r/min, reaction time 2 h and liquid concentration 4.17 mol/L, the first carbonization rate reached 70%. When the first carbonation rate was 60% and total chromium concentration 5 mol/L, the secondary carbonization rate reached 95%.

生化工程专栏

Separation of Alkaloids in Sophora flavescens Ait. by Aqueous Two-phase Extraction

LIU Xiao-qin ZHANG Wei FAN Hua-jun WANG Li-ping HUANG Xiao-wen FENG Ying ZHU Dan

. 2012, 12(4):  641-647. 

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Using ethanol, polyethylene glycol and Triton X-100 combined with inorganic salts separately, several aqueous two-phase systems were developed, including ethanol/(NH4)2SO4 and PEG/(NH4)2SO4, and Their properties and capacities investigated. The results showed that ethanol/(NH4)2SO4 system easily formed, being stable for fast and high rate extraction of alkaloids such as oxymatrine and matrine. The effects of amounts of ethanol and (NH4)2SO4, pH value, temperature and extraction time were optimized further for the ethanol/(NH4)2SO4 system. Their optimal values were 38%(w) of ethanol, 18%(w) of (NH4)2SO4, pH=7.0, 30℃, and 15 min under electromagnetic stirring. The partition coefficient K and extraction rate for oxymatrine and matrine were up to 4.46 and 5.10, and 96.17% and 95.74%, respectively. Adding a certain amount of ethanol and (NH4)2SO4 in the sample extracted by water, the aqueous two-phase system directly formed for extraction of oxymatrine, N-oxysophocarpine, sophoridine, matrine and sophocarpine from it. The first extraction rate of five alkaloids was between 91.03% and 94.46%, and total extraction rate from 97.22% to 98.78% after three times of extraction. Ethanol/(NH4)2SO4 system was successfully applied to purify alkaloids in the aqueous sample extracted from Sophorae flavescens Ait. The relative contents of alkaloids above were increased by more than one times, and those of impurities removed significantly. The extraction of alkaloids was a spontaneous process of endothermic and entropy increase because of less than zero of DH0, greater than zero of DS0 and less than zero of DG0, respectively.

Adsorption Kinetics and Thermodynamics of Theanine onto Anion Exchange Resins

TIAN Si-si WANG Xia WANG Hao-qi YAO Zhong ZHOU Zhi SUN Yun XIONG Qiang XU Hong

. 2012, 12(4):  648-653. 

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To separate the synthesized theanine by enzymatic method, the adsorption of theanine onto anion exchange resins under alkaline condition was investigated. The results revealed that the adsorption properties of strongly basic resins were better than that of weakly basic resins. While the gel-type basic resin of HZ202 was used, its equilibrium adsorption capacity for theanine was 96.3 mg/g at pH 9.0. The experimental results showed that theanine was loaded on the HZ202 resin with a non-uniform distribution. The isotherm data well fit to Sips model. The DG change was all negative at different temperatures, indicating that the adsorption process was exothermic and spontaneous. Enthalpy change lied between 20.9~418.4 kJ/mol, suggesting that the adsorption process was chemical adsorption. The kinetic data of adsorption fit well to the pseudo-second-order model. It suggested that the adsorption rate was limited by chemical reaction. The adsorption rate would be improved with increasing of initial concentration of theanine.

Removal of Sulfate from Threonine Isoelectric Supernatant by Bipolar Membrane Electrodialysis

ZHANG Wei-ling ZHANG Li-ye; YANG Peng-bo CONG Wei WANG Qian;

. 2012, 12(4):  654-659. 

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The desalination of sulfate in threonine isoelectric supernatant by three-compartment electrodialysis with bipolar membrane was studied. The device performance during five successive batches of electrodialysis was investigated. In addition, the area resistance of ion-exchange membranes before and after batch operation was measured to detect the membrane fouling. The results showed that the transform rate of sulfate in threonine isoelectric supernatant reached 97%, and H+ concentration of 0.49 mol/L and OH- concentration of 0.44 mol/L were obtained by the electrodialysis in acid and base cells, respectively. Whereas, the average current efficiency and energy consumption of the three-compartment electrodialysis with bipolar membrane calculated on the basis of cations were 60.33% and 229.37 kW×h/kmol, respectively. With increasing of batch runs and prolonging of operation time, the energy consumption of unit flux and average stack resistance increased, and average current efficiency and flux decreased, the device performance was deteriorated. Moreover, the area resistance of anion and bipolar membranes was increased by 44.8% (1.77 W×cm2) and 19.5% (0.91 W×cm2), respectively, which was caused by membrane fouling.

Construction of Colon-specific Drug Delivery System with pH-dependency 5-ASA Using Grafted CPVA-g-PSSS Microspheres

MEN Ji-ying GAO Bao-jiao YAO lan ZHANG Yan-yan

. 2012, 12(4):  660-664. 

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The graft-polymerization of sodium 4-styrene sulfonate (SSS) was performed on the surface of crosslinked polyvinyl alcohol (CPVA) microspheres with cerium salt-hydroxyl group redox initiation system, the grafted CPVA-g-PSSS microspheres with strong anionic polyelectrolyte PSSS were obtained. On this basis, the adsorption property of the microspheres for 5-amino salicylic acid (5-ASA), namely drug carrying ability, was investigated and the adsorption mechanism analyzed. The in vitro release behavior of the drug-carried microspheres was also examined. The experimental results show that the grafted CPVA-g-PSSS microspheres exhibit very strong adsorption ability for 5-ASA by driving of electrostatic interaction in the acidic medium. Their adsorption capacity can reach 39.1 mg/g, displaying a high efficiency of drug-loading. Their in vitro release behavior is highly pH-dependent. In the medium of pH=1, the drug is not released, while in that of pH=7.4, the burst release occurs, displaying an excellent colon-specific drug delivery behavior.

材料工程专栏

Preparation and Application of Nano-composite Poly(vinyl alcohol) Gel Electrolyte in Electrochemical Capacitor

CHEN Yun TAN Qiang-qiang XU Yu-xing

. 2012, 12(4):  665-671. 

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A nano-composite polymer gel electrolyte was prepared using titanium oxide nanowire, poly(vinyl alcohol) (PVA), lithium salt and organic solvent N-methyl-2-pyrrolidone (NMP). The obtained electrolyte has the potential for application in electrochemical capacitor, the PVA in it is in an amorphous state. The ionic conductivities of electrolytes increased after addition of the nanowire, and the electrolyte with 3%(w) of nanowire exhibited the highest ionic conductivity of 3.2 mS/cm at 20℃, as measured by electrochemical impedance spectroscopy. The temperature dependence of the conductivity was found to be in agreement with the Arrhenius equation. Functioning as separator and electrolyte, this nano-composite PVA gel electrolyte was used to assemble the electrochemical capacitor with active carbon film as electrodes. The compositing of nanowire may extend the life of electrochemical capacitors as they keep more than 90% of their capacitance after 5000 cycles of charging and discharging.

Preparation and Properties of Conductive Poly(3,4-ethylene dioxythiophene)/Polyaniline Composite

HUANG Hui; FU Ren-chun ZHU Wei GUO Zhong-cheng;

. 2012, 12(4):  672-677. 

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Conductive poly(3,4-ethylene dioxythiophene)/polyaniline (PEDOT/PANI) composite was synthesized by chemical oxidative polymerization with ammonium persulfate and ferric chloride as oxidant. Its properties were studied on the effects of addition time aniline, molar ratios of FeCl3 to APS in composite oxidant and SDBS to CTAB in composite emulsifier and aniline concentration. The results show that the optimal synthesis conditions of PEDOT/PANI are: EDOT 0.6 mol/L, composite oxidant 0.6 mol/L (FeCl3:APS=1:2, mol), composite emulsifier 0.4 mol/L (SDBS:CTAB=2:3, mol), concentration of composite doping agent 1.2 mol/L (H2SO4:SSA=4:1, mol), and aniline 0.8 mol/L. After 2 h, aniline solution is added and continued to react for 8 h. PEDOT/PANI composite has better conductivity, crystalline and thermal stability than that of pure PEDOT and PANI.

Preparation of Silane Modified ZSM-5 Zeolite/BPPO Asymmetric Membrane and Its Pervaporation Performance

ZENG Xiao-ya JI Shu-lan ZHAO Liang QIN Zhen-ping ZHOU Qian-hua

. 2012, 12(4):  678-683. 

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With silane modified ZSM-5 zeolite as filling agent, ZSM-5/BPPO [bromide poly(2,6-dimethyl-1,4-phenylene oxide)] asymmetric membrane was successfully prepared by phase inversion process. The SEM and AFM images showed that the zeolite was uniformly distributed within the membrane, and the ZSM-5/BPPO membrane had a higher surface roughness. The analysis of contact angel showed that the ZAM-5/BPPO membrane was more hydrophobic than the BPPO membrane. The effects of ZSM-5 content, feed solution concentration and temperature on the pervaporation performance of dilute ethanol-water solution were examined. The results showed that the separation performance of ZSM-5/BPPO membrane was excellent. With increasing of ethanol concentration in feed solution, the membrane selectivity decreased, while the permeation flux increased. With increasing of feed solution temperature, both the separation factor and the permeation flux increased. When the ZSM-5 content was 0.3%(w), feed concentration 5%(w) and feed solution temperature 60℃, the total permeation flux and separation factor could reach 529.69 g/(m2×h) and 18.49, respectively. The pervaporation performance of ZSM-5/BPPO membrane on different alcohol-water mixtures showed that the higher the alcohol molecular weight, the better the separation performance.

Enhanced Catalytic Ozonation of Oxalic Acid over Modified Activated Carbon

WU Guang-guo XIE Yong-bing XING Lin-lin CAO Hong-bin

. 2012, 12(4):  684-689. 

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Industrial activated carbon (AC) was pretreated by acid solution and modified by nitration and amination. Its catalytic performance was investigated in a semi-batch reactor. After the acid pretreatment, the specific surface area, pHpzc and content of basic groups of AC were increased about 5%~10%, but its catalytic activity decreased 15.6%. The pHpzc and content of basic functional groups on the surface of AC-NH2 were increased from 2.6 and 234.8 mmol/g to 7.0 and 764.5 mmol/g, respectively. But all of them decreased after nitration. The modified AC samples were more active than the original AC and acid pretreated AC in the catalytic ozonation of oxalic acid at acid and neutral conditions. The degradation rate of AC-NH2 catalytic ozonation of oxalic acid was 42.4% in 45 min in the solution at pH=7. Catalytic ozonation of oxalic acid was inhabited by adding tert-butanol. This indicated that the modified activated carbon catalytic ozonation followed the hydroxyl radical reaction mechanism.

Selective Hydrogenation of Cinnamaldehyde over Cu/Al2O3 Catalyst Prepared by Coprecipitation

ZHANG Bin ZHANG Xin-bo XU Li-yong ZHANG Ya-juan QIN Yong-hua

. 2012, 12(4):  690-695. 

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A series of alumina supported Cu catalyst were prepared by coprecipitation method. XRD, N2 physical adsorption and SEM were used to study the catalysts. Its catalytic performance in cinnamaldehyde (CMA) hydrogenation was investigated. The results showed that the catalyst prepared by coprecipitation had higher activity of cinnamaldehyde hydrogenation compared with the catalyst prepared by impregnation. The active component particle size increased with the increase of calcination temperature, while the conversion rate of cinnamaldehyde increased firstly and then decreased. The catalyst reduced at 873 K showed the highest activity of cinnamaldehyde hydrogenation. The conversion rate of CMA increased with the increase of reaction temperature, but the cinnamyl alcohol selectivity decreased. The conversion rate of CMA was 14.7% and the selectivity of cinnamyl alcohol 56.5% at 2 MPa and 363 K after reaction 4 h.

Experimental Study on Photocatalytic Degradation of Indoor Formaldehyde Gas over Copper-doped Titania

ZHANG Hao LIU Xiu-yu ZHU Qing-ming DING Hou-cheng

. 2012, 12(4):  696-701. 

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TiO2 nanocrystallite photocatalyst doped with Cu by sol-gel method was prepared, the optimal content of Cu in TiO2 was 2.0%(mol). Its photocatalytic activity was determined, and removal effect of formaldehyde investigated by the photocatalytic decomposition of formaldehyde gas in the environmental chamber using a visible lamp. When the dosage of Cu-TiO2 photocatalyst was at 1.5~2.5 g/m3, and initial concentration of formaldehyde gas 1 mg/m3, the degradation of formaldehyde gas in the environmental chamber had the best effect. Compared with a commercially available P25 photocatalyst, the Cu-TiO2 photocatalyst in the visible range had good degradation of formaldehyde, and after repeated use, the photocatalyst was still kept in its good photocatalytic activity.

综述

Advances in Simulation of Liquid-Liquid Two-phase Flow in Extraction Columns with CFD-PBM

LI Shao-wei JING Shan ZHANG Qi WU Qiu-lin

. 2012, 12(4):  702-711. 

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A detailed review on the CFD-PBM research in the extraction columns is presented, including the fundamental theory, different solution methods, and status of the simulation research. The basic equations in the CFD-PBM simulation contain the flow equations and the population balance equation, which are coupled with each other. Coalescence and break-up models are two important models in the population equation. The methods to solve the population balance equation include the class method, the method of moments, the quadrature method of moments, the direct quadrature method of moments, and the sectional quadrature method of moments. The fundamental, advantages and disadvantaged of these methods were reviewed. The Eulerian-Eulerian method is mainly used in the CFD simulation of the two-phase flow in extraction columns to date. The PBM which considers the droplet size distribution and further the concentration distribution is relatively less used in extraction columns. To improve the PBM in a liquid-liquid dispersion system with mass transfer and to use the model in different types of extraction columns are important issues for extraction research.

Research Advances in Directly Heated Cracking of Hydrocarbons by Heat Carrier Gas?II. Pyrolysis Process

JING Xiao-dong ZHAO Yue-hong WEN Hao XU Zhi-hong

. 2012, 12(4):  712-720. 

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Recent advances in directly heated cracking process using heat carrier gas in industry were reviewed, focusing on the process composition, operating conditions, product yields, reaction mechanism and progresses of the processes of directly heated cracking using heat carrier gas. Finally, we provide the outlook for the future development of directly heated cracking process using heat carrier gas and draw a conclusion that directly heated cracking process using superheated steam produced by combustion of hydrogen and oxygen as heat carrier gas will have big development space in enhancing heat efficiency, lowering CO2 emission and on-line decoking, and will specially be one of the most promising techniques for high feedstock flexibility and high olefin yields.