Table of Content

20 June 2015, Volume 15 Issue 3

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Experiment and Simulation of Dense Gas-Solid Two-phase Flow in a Rectangular Cross-flow Moving Bed

WANG Ruo-jin XU Jun LONG Wen-yu FAN Yi-ping LU Chun-xi

Chin. J. Process Eng.. 2015, 15(3):  361-367.  DOI: 10.12034/j.issn.1009-606X.215136

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Based on the experimental result, Eulerian two-fluid model was used to investigate the cavity, pinning, flow streamlines, gas residence time and pressure distribution in a rectangular cross-flow moving bed. The results showed that the gas-solid two-phase flow was influenced by the end-effect. As the superficial gas velocity increased to about 0.19 and 0.31 m/s, the pinning and cavity appeared respectively. The cavity changed with time, while the pinning was virtually progressive. The shapes of both the cavity and pinning were determined greatly by the superficial gas velocity. The gas velocity distribution, cavity and pinning led to the pressure distribution profile in the shape of reverse C. The pressure drop ratio of the feed influencing zone to the gas-solid contact zone and discharge influencing zone was about 6:10:9. With increasing of the superficial gas velocity, the gas residence time decreased, both the cavity size and pressure drop increased, while the pinning thickness increased first and then remained almost unchanged. But the solids flux had little effect on the investigated parameters.

Analysis on Flow Field in a Multi-tube Cyclone Separator at Gas Transmission Station

HAN Chuan-jun YANG Xue LI Qi

Chin. J. Process Eng.. 2015, 15(3):  368-374.  DOI: 10.12034/j.issn.1009-606X.215157

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The separation efficiency and pressure drop of a multi-tube cyclone separator were simulated to evaluate its separation performance in the inlet velocity range from 7 to 27 m/s, particle density 1000 to 5000 kg/m3, particle total flow rate 2.5~2500 g/m3 and operating pressure 1 to 5 MPa. The results show that the pressure drop of multi-tube is mainly composed of that from single tubes, being about 80%~90% of the whole pressure drop. The distribution of flow field in single tubes is the same as that in the multi-tube state, with symmetrical distribution along the axial direction and minimum value at the central vortex core. The separation efficiency and pressure drop of 21-tube cyclone increases with increasing of inlet velocity, and the separation efficiency increases from 30.57% to 63.86% while the pressure drop increases from 9053 to 116864 Pa when the particle diameters distribute in the range of 1~10 mm. This structure could separate particles almost completely if their diameters were bigger than 6 mm. And with increasing of particles density, the separation efficiency rises up while the pressure drop almost remains unchanged. When operation pressure increases, the separation efficiency becomes lower, but the pressure drop slightly increases. Besides, the air inflow fluctuation of all the 21 cyclone tubes will not exceed 5%.

Experimental Study on the Acting Forces on a Single Slant Slat Immersed in a Gas and Fine Particles Fluidized Bed

WANG Ruo-yi LIU Dui-ping LI Zhi ZHANG Yong-min

Chin. J. Process Eng.. 2015, 15(3):  375-380.  DOI: 10.12034/j.issn.1009-606X.215155

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A single cantilever slant slat was installed in a cold-model fluidized bed of fine particles with a square cross section. The dynamic force on it during the operation of fluidized bed was measured by a dynamic stress meter. Meanwhile, the dynamic pressures in the bed were also measured by pressure transducers. The main influential factors considered were superficial gas velocity, installation height above the gas distributor and inclination angle of the slat. The results indicated that the main energy of dynamic stress on the slat dropped in the frequency range of 0~50 Hz. There was a maximum root mean square (RMS) of the dynamic stress at a superficial gas velocity of 0.5~0.6 m/s, which was near the transitional point between the bubbling and turbulent flow regimes. Along the height of dense bed, the RMS of stress was found to be lower when the slat was installed in the middle section of bed. At different inclination angles, there were minimal values of the stress RMS occurring at 15o, 45o and 60o.

Hydraulic Performance of Sieve Runde Tray

CAO Wan-wan GUO Jian-quan FAN Xuan CHU Ya-zhi MA Xiao-xun

Chin. J. Process Eng.. 2015, 15(3):  381-385.  DOI: 10.12034/j.issn.1009-606X.215129

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The hydraulic performance of sieve Runde tray was studied with water and air as working media, the effects of opening ratio of fixed valve, F factor and spray density on dry pressure drop, total pressure drop, clean liquid height, average foaming height and operating flexibility were examined in cold model experiments, and compared with conventional sieve dual flow tray under the same conditions. The results show that the operating flexibility of sieve Runde tray is 51.4% lager than that of conventional sieve dual flow tray on average in the experimental conditions. The total pressure drop under the opening ratio of fixed valves of sieve Runde tray at 33.3% is 72.38% lower than that of conventional sieve dual flow tray on average, and its dry pressure drop is 88.8% and 206.3% lower than that of the opening ratios of fixed valves at 50.0% and 66.7% on average. The optimal opening ratio of fixed valves is 33.3%. The correlations of experimental data is obtained for calculation of the dry pressure drop of the tray as pd=49.98F1.785.

Mass Transfer Performance of CO2 Absorption by Two-component Blended Organic Amine Solutions

LI Hu LIU Ying-shu ZHANG Hui ZHENG Xin-gang YANG Xiong

Chin. J. Process Eng.. 2015, 15(3):  386-392.  DOI: 10.12034/j.issn.1009-606X.215121

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An experimental packed tower was set up to study the absorption of high-concentration CO2 in aqueous solutions of blended organic amine with diethanolamine (DEA) as base solvent, and N-methyldiethanolamine (MDEA), (N-2-hydroxyethyl) ethylenediamine (AEE), diethylenetriamine (DETA) and triethylenetetramine (TETA) as additives respectively. The effects of concentration and species of additives on the mass transfer performance, such as conversion rate of CO2 h, volumetric overall mass transfer coefficient KGae, and gas and liquid phase mass transfer resistance, were systematically examined. The results show that KGae and h increase with increasing of additive concentration when AEE, DETA and TETA are taken as additives. And the gas phase mass transfer coefficient kG and gas phase mass transfer resistance decrease, but liquid phase mass transfer resistance increases. For the additive of MDEA, the trends were just contrary to the above. In the absorption process of CO2 in two-component blended organic amine solutions, the values of KGae and h increase along the tower packing height, which follow the order of DEA-TETA > DEA-DETA > DEA-AEE > DEA-MDEA.

Removal of Boron Impurity from Metallurgical Grade Silicon by Composite Solvent Refining

DU Bing WANG Zhi SUN Li-yuan MA Wen-hui GE Zhi CHEN Hang

Chin. J. Process Eng.. 2015, 15(3):  393-399.  DOI: 10.12034/j.issn.1009-606X.215175

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Sn-Si alloy was refined for removal of boron by composite solvent refining with CaO-SiO2-Al2O3 slag at 1550℃, and the effects of optical basicity of slag and alloy composition on the removal of B and refining mechanism were examined. The results showed that with increasing of the optical basicity, the activity coefficient of BO1.5 decreased obviously, the partition ratio of B increased, leading to the enhancement of refining. When the content of Sn in the alloy increased from 0 to 70%, the partition ratio of B increased from 3.16 to 13.8, the lowest content of B was 0.89′10-6, and the highest removal rate of 93.3% achieved. When the content of Sn was over 30%, the viscosity of Sn-Si alloy substantially decreased, resulting in rising of the partition ratio of B. When the content of Sn was 70% and the viscosity of alloy 0.61 mPa×s, the highest values of partition ratio of B in both CaO-SiO2-20% Al2O3 and CaO-SiO2-40% Al2O3 slag systems were 10.1 and 12.3, respectively.

Leaching Technology and Kinetics of Vanadium from Vanadium and Chromium-bearing Slag by Alkaline Process

GUO Chao ZHANG Yang QIAO Shan ZHENG Shi-li XIE Hua

Chin. J. Process Eng.. 2015, 15(3):  400-405.  DOI: 10.12034/j.issn.1009-606X.215156

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Vanadium was extracted from vanadium and chromium-bearing slag from the vanadium smelting process by air oxidation process and alkaline leaching process under atmospheric pressure. The effects of alkali concentration, leaching temperature, ratio of liquid to solid on the leaching rate of vanadium by orthogonal experiments were examined, and the leaching kinetics was also studied. The results showed that the optimum leaching conditions were the NaOH concentration of 100 g/L, leaching temperature 100℃, ratio of liquid to solid 4 mg/L and leaching time 1 h. Under the conditions, the leaching rate of vanadium reached 98%. Vanadium leaching process was in line with nuclear shrinkage model, the leaching process was controlled by diffusion step, and the apparent activation energy was 11.04 kJ/mol.

Oxidizing Acid Leaching of Nickel-based Waste Superalloys Containing Rhenium

WU Jian-hui SU Tao LIU Gang ZHANG Wen-hong WEI Tao LUO Mei-mei

Chin. J. Process Eng.. 2015, 15(3):  406-411.  DOI: 10.12034/j.issn.1009-606X.215144

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The melting atomization for powder preparation and oxidizing acid leaching of nickel-based waste superalloys containing rhenium with addition of hydrogen peroxide in sulfuric acid system were adopted for leaching of rhenium, molybdenum, tungsten, tantalum and other rare metals, nickel and cobalt were leached from waste superalloys, and tungsten, tantalum and other rare metals enriched in the leaching residue. The effects of sulfuric acid concentration, volume of hydrogen peroxide, temperature, particle size, ratio of liquid to solid and leaching time on the leaching rates of metals were examined. The optimized leaching conditions were obtained as the alloy powder 20 g, particle size 71~100 mm, temperature 75℃, ratio of liquid to solid 8 mL/g, sulfuric acid concentration 3.5 mol/L, volume of 30%(w) hydrogen peroxide 65 mL, which was dropwise added, and reaction for 6 h in sulfuric acid system. Under the above conditions, the leaching rates of nickel, cobalt and rhenium were all over 99%, those of tungsten and tantalum less than 1%, and that of molybdenum is 28%. So, Re was completely leached into solution, and rare metals were enriched in residue.

Effects of Synthesis Methods for Scorodite on Its Leaching Stability

LIU Zhi-hong YANG Xiao-feng LIU Zhi-yong LI Yu-hu LI Qi-hou

Chin. J. Process Eng.. 2015, 15(3):  412-417.  DOI: 10.12034/j.issn.1009-606X.215153

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Scorodite was synthesized under both addition and without addition of crystal seed by atmospheric, hydrothermal and improved atmospheric synthesis methods, ASP, HSP and IASP in abbreviation, and its crystal structure, crystallinity, morphology, particle size, specific surface area, Fe/As mole ratio and leaching stability were characterized, aiming at revealing the relationships among the synthesis methods, composition, structural properties and leaching stability of scorodite. The results show that the synthesis method has significant effect on the composition and structural properties. Scorodite with high crystallinity, small specific surface area, and low Fe/As mole ratio possesses high leaching stability. The order of leaching stability of synthesized scorodite samples follows the order of ASP < HSP < IASP. The scorodite sample synthesized by IASP without addition of crystal seed appears in crystalline particles with large size and pyramidal morphology enclosed by {111}, and possesses the crystallinity of 84.5%, particle size (D50) of 28.2 mm, BET specific surface area of 3.72 m2/g and Fe/As mole ratio of 1.05. With HJ/T300 method, the leaching stability of scorodite sample was tested, after leaching for 10 d, the total arsenic concentration in the leaching solution is only 1.14 mg/L.

Leaching Behaviors of Heavy Metals from Electric Furnace Refining Slag in Different Solutions

MA Chi LI Hui-quan WANG Chen-ye BAO Wei-jun XU De-hua LIAO Dan-kui HUANG Ke-lin

Chin. J. Process Eng.. 2015, 15(3):  418-423.  DOI: 10.12034/j.issn.1009-606X.215125

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The leaching behaviors of heavy metals in electric furnace refining slag were studied by total dissolving, short-term and long-term leaching experiments, and the leaching mechanism was analyzed by SEM and XRD. The results show that in the slag, the concentration of Ba from short-term leaching is higher than the discharge standard of wastewater containing heavy metal, and the concentrations of Ni from short-term leaching and V from long-term leaching are higher than the hygiene standard of domestic and drinking water. Leaching of heavy metals is mainly due to the structural damage of Ca2SiO4×H2O (C-S-H) in the slag.

Recovery of Copper from Chlorination Dust of Copper-containing Slag by Hydrometallurgical Methods

XIE Xiao-feng LI Lei WANG Fei YU Jun-qiang QIU Shi-wei ZHANG Ren-jie

Chin. J. Process Eng.. 2015, 15(3):  424-429.  DOI: 10.12034/j.issn.1009-606X.215128

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Copper in the chlorination dust of copper-containing slag was recovered through the hydrochloric acid agitation leaching-N902 extraction process, and the main influential factors on the leaching of the chlorination dust were studied. The results show that under the conditions of 15% concentration of hydrochloric acid, ratio of liquid to solid 4 mL/g, reaction temperature 60℃ and reaction time 1 h, the leaching rate of copper is 98.95%. Meanwhile, the leaching rates of iron, nickel and zinc are 91.58%, 95.8% and 93.66%, but the leaching rate of lead is low at 5.96%. The leaching process realizes the separation of copper and lead effectively. N902 for copper extraction has good selectivity. When the mixing time, phase ratio, N902 concentration and pH value are 120 s, 1:1, 30% and 3.0 respectively, the copper concentration in the leaching solution decreases from 7.4 to 0.11 g/L, the extraction rate of copper is 98.51%, and the extraction rates of iron, nickel, zinc and lead are all lower than 1.5%.

Change of Iron-containing Phases in Steelmaking Slag in Leaching Process with Organic-Inorganic Composite Medium

REN Yun-liang WANG Chen-ye ZHANG Hong-en BI Ya-mei LI Hui-quan PANG Jie

Chin. J. Process Eng.. 2015, 15(3):  430-434.  DOI: 10.12034/j.issn.1009-606X.215188

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Steelmaking slag was leached in organic-inorganic composite medium composed of acetic acid and tributyl phosphate. The main existing form and phase distribution of iron in the leached slag were investigated by combination of SEM, EDS, XPS and FT-IR. The results show that the iron phases in raw slag include elemental iron, iron oxide, ferrite and RO phase, while in the leached slag there are iron oxides and iron hydroxides, 88.9% in the form of Fe3+ and 11.1% in the form of Fe2+. The iron resource could be recovered from the leached steelmaking slag by further magnetic separation.

Control of the Stability of Solid-Liquid Interface and Growth of Si Crystal during Solvent Refining Process of Al-Si Alloy

CHEN Hang WANG Zhi CHI Ru-an JING Qing-xiu SUN Li-yuan DU Bing

Chin. J. Process Eng.. 2015, 15(3):  435-442.  DOI: 10.12034/j.issn.1009-606X.215187

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To solve the problem of separation of Si crystal with melting agent, the stability of solid-liquid interface was controlled during Si crystal growth in Al-Si melt by combining electromagnetic and thermal fields, and the functional mechanism of physic fields during the crystallization analyzed. The result showed that with increasing of Si content in Al-Si melt, the occurrence of compositional supercooling phenomenon was more difficult, and the solid-liquid interface was more stable, which was beneficial to the densification of Si crystals. When the inner diameter of crucible was reduced from 3 to 1 cm, the temperature distribution in the alloy melt changed, and the curvature of solid-liquid interface varied from 16.7 to 125, which resulted in denser Si crystals, enhanced separation efficiency of Si crystals with melting agent, and reduced existing portion of Si crystals from 0.57 to 0.42. The slower the lowering rate, the stabler the solid-liquid interface, and the better the in situ separation effect of Si crystals with melting agent. When the lowering rate was 0.05 mm/min, the content of Si crystals reached 99.9% at the bottom of sample, while the Si crystals could hardly be found on the top. Electromagnetic stirring could strengthen the flow and mass transfer in the melt, so the Si content in the frontier of solid-liquid interface was increased and the interfacial stability enhanced.

Distributions of Gaseous Products from the Flash Pyrolysis of Coal and Biomass in Coal Topping Process

JIN Hui-xin WU Fu-zhong WANG Yang WANG Mei-long

Chin. J. Process Eng.. 2015, 15(3):  443-450.  DOI: 10.12034/j.issn.1009-606X.215105

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The flash pyrolysis experiments of coal, biomass and their mixture under the simulative conditions of coal topping process were carried out. The effects of pyrolysis temperature and samples on the yield of products, compositions of gas and net calorific value of gas were studied. The results showed that pyrolysis of the mixture of lignite and biomass obeyed the pyrolysis law of single substance, but the additive amount of biomass affected the yield of pyrolysis products. When the mass ratio of biomass to lignite was less than 1:1, the yield of gas increased from below 50% to above 60%, however, while the addictive amount of biomass increased to over 50%, the yield of gas decreased 5%. For the gaseous compositions of pyrolysis of lignite, biomass and their mixture, there were similar changing rules, CO2 was the main component, followed by CO, H2 and hydrocarbon gases. Among hydrocarbon gases, the content of CH4 and C3H6 was higher than that of C2H4, C2H6 and C3H8, and that of C4H8 the least. In addition, the content of CH4 in the gas from the mixture pyrolysis was 20% higher than that from lignite pyrolysis. Pyrolysis temperature had a significant effect on net calorific value of gas, which was increased at high temperature. Under the condition of 500~800℃ of pyrolysis temperature and mass ratio of biomass to lignite at 1:2, the net calorific value of gas increased from 11.38 to 16.10 MJ/m3. Therefore, high yield and calorific value of gas could be obtained for flash pyrolysis of the mixture of lignite and biomass in coal topping process.

Roasting Reduction Kinetics of Low-grade Pyrolusite with the Mixture of Cellulose and Hemicellulose

LONG Yun-fei LV Yi-ju SU Jing LV Xiao-yan WEN Yan-xuan

Chin. J. Process Eng.. 2015, 15(3):  451-456.  DOI: 10.12034/j.issn.1009-606X.215162

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The reduction kinetics of pyrolusite by cellulose and hemicellulose, and their mixture was investigated by TG/DTG and XRD. The results show that compared with the non-biomass reducing agents, pyrolusite can be reduced below 773 K which is close to that of biomass reducing agents. The respective reduction processes follow the empirical equation a=1-exp{-k0exp(-Ea/RT)[(T-T0)/b]n}, and the apparent activation energy is 38.66 and 30.14 kJ/mol for the reduction of pyrolusite by cellulose and hemicellulose, respectively. The reduction kinetics of pyrolusite by the mixture can be described by the summation of the respective kinetics by considering their mass-loss fractions a=Sixiaie(T-T0,i) with Sixi=1, where e(T-T0) is the unit step function to avoid the invalid conversion data.

Effect of Basicity on Sintering of Cr-bearing Vanadium and Titanium Magnetite Ore

ZHOU Mi JIANG Tao WANG Yan-jun YANG Song-tao ZHANg Li-heng XUE Xiang-xin

Chin. J. Process Eng.. 2015, 15(3):  457-462.  DOI: 10.12034/j.issn.1009-606X.215140

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The effect of basicity (R) on sintering of Cr-bearing vanadium and titanium magnetite ore was studied via sintering pot experiment on the basis of production conditions in Chengde Jianlong Special Steel Company, and the sinter characterized. The results showed that with the increase of basicity, the sintering rate rose firstly, and then fell with a increasing burning loss, leading to a max sintering rate of 19.70 mm/min at R=2.5. Tumbler strength of sinter had the maximum value was 63.53% when the basicity was 2.7. Meanwhile, increasing the basicity was beneficial to the improvement of low-temperature reduction degradation index (RDI) of sinter, and its maximum value of powders size larger than 3.15 mm was 75.09% at R=2.7. Moreover, with the increase of basicity, productivity rose firstly, then fell, and had a maximum value of 1.35 t/(m2×h) when R=2.5. The fuel consumption ratio rose at R=2.1~2.5, and its minimum value was 43.21 kg/t when R=2.1. In addition, increasing basicity was also beneficial to the softening properties through improving the beginning and ending softening temperatures of sinter. The improvement in mineral composition and structure aroused by increasing the basicity was the essential reason for improving sintering properties. Overall, the optimal basicity of V-Ti-Cr sinter for industrial application was 2.5.

Synthesis of Isooctyl Acetate by Transesterification and Removal of Alcohol with Adsorption

DING Bin HAO Feng-ling GUAN Chang LI Xiang WANG Hai-dong LIU Qun

Chin. J. Process Eng.. 2015, 15(3):  463-467.  DOI: 10.12034/j.issn.1009-606X.214310

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Isooctyl acetate was synthesized with ethyl acetate and iso-octyl alcohol as raw materials, cation exchange resin NKC-9 as catalyst and 4A zeolite as dealcohol adsorbent. The effects of molar ratio of ethyl acetate to isooctyl alcohol, catalyst dosage, reaction temperature and time on the transesterification were examined. The results showed that the optimum reaction conditions were obtained as the molar ratio of ethyl acetate to isooctyl alcohol at 3.0:1, catalyst dosage 6.0% (referring to total mass of ethyl acetate and isooctyl alcohol), reaction temperature ≤98℃, and reaction time 4.0 h. Under the conditions, the content of isooctyl acetate in the reaction solution could achieve 60.51%.

Emission Characteristics of Soot Particles from Combustion of Fuel Mist in a Fuel Oil Boiler

HE Jin-qiao CAO Xiong SUN Zhi-cheng ZHAO Hua-geng

Chin. J. Process Eng.. 2015, 15(3):  468-472.  DOI: 10.12034/j.issn.1009-606X.214349

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A non-premixed combustion model was established based on the chamber structure and heat transfer characteristics of a 2 t/h horizontal shell oil-fired boiler, and the effect of wind speed on the mist combustion and emission characteristics of soot particles analyzed. The results showed that the fuel concentration in the chamber rapidly reduced along the axial direction in 0.3~0.7 m from the fuel nozzle. The soot particles were quickly generated in the mixed combustion zone from the fuel nozzle of 0.3~1.5 m, and went away from the nozzle with increasing of wind speed. The largest generation rate appeared at the ignition point. When the wind speed was too big or too small, the generated soot particles increased. When the wind speed was 7.5 m/s, the soot concentration was the smallest and most evenly, and its value was 0.042%(w).

Preparation of Uniform-sized pH-sensitive HTCC Hydrogel Microspheres by Premix Membrane Emulsification and Thermal Gelation

LIU Yan WANG Yue-qi FAN Qing-ze WU You-bin WU Jie MA Guang-hui

Chin. J. Process Eng.. 2015, 15(3):  473-481.  DOI: 10.12034/j.issn.1009-606X.215147

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N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) hydrogel microspheres were prepared by premix membrane emulsification and thermal gelation methods, using HTCC/a-b-glycerophosphate mixed system with the property of thermal gelation as water phase. The effects of preparation conditions on size distribution, structure and drug encapsulation efficiency of microspheres, including transmembrane pressure, formulation of water phase and oil phase, volume ratio of water to oil phase and pore size of microporous membrane, were examined. After optimization, uniform-sized microspheres (polydispersity, PDI<0.1) with different sizes and high drug encapsulation efficiency (75.49%±2.62%) were obtained. The cytotoxicity and pH-sensitivity of as-obtained hydrogel microspheres were evaluated in comparison with the microspheres prepared by traditional method. The results showed that the as-obtained hydrogel microspheres possessed good biocompatibility and outstanding pH-sensitivity, and remained stable in neutral/alkalescent media and released drug in a relatively slow manner, with the drug cumulative release rate of 34.6% at 24 h in buffer solution at pH=7.4. While the hydrogel microspheres collapsed in acidic solution and led to a repaid drug release, and the cumulative release rate reached up to 79.6% in 1 h in buffer solution at pH=5.5.

Chromatographic Separation of Octreotide with Prepared Polydivinylbenzene Microspheres

ZHANG Chen-xu LI Qiang HUANG Yong-dong; ZHAO Lan ZHANG Rong-yue GONG Fang-ling; SONG Cui SU Zhi-guo YUAN Qi-peng MA Guang-hui

Chin. J. Process Eng.. 2015, 15(3):  482-488.  DOI: 10.12034/j.issn.1009-606X.215149

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Polydivinylbenzene (pDVB) microspheres with the particle size of 14.2 mm were prepared with divinylbenzene as monomer by membrane emulsification and suspension polymerization at 75℃ for 20 h. The prepared pDVB microspheres had uniform particle size (Rspan=0.71), mean pore size of 65 nm and specific surface area of 160 m2/g. The pDVB microspheres were packed into f4.6 mm′250 mm stainless steel column by slurry packing method, and tested in separation of peptide drug by high performance liquid chromatography. Afterword, a very fast separation process of octreotide from synthetic peptide crude mixtures on pDVB reversed phase was carried out. Fourier-transformed infrared resonance (FT-IR) spectroscopy, and reversed-phase HPLC combined with electrospray ionisation mass spectrometry (ESI-MS) were used for analysis of resultant peptides. Under the optimized conditions, the octreotide was purified from 42.89% to 99.99%.

Effects of pH Value on Co-production of Butanol and Hydrogen by Clostridium beijerinckii Fermentation and Kinetic Modeling

CHEN Pan WU Hao HE Ai-yong KONG Xing-ping MA Jiang-feng ＣＨＥＮＧ　

Chin. J. Process Eng.. 2015, 15(3):  489-494.  DOI: 10.12034/j.issn.1009-606X.215146

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The effects of pH value on co-production of butanol and hydrogen by fermentation with Clostridium beijerinckii IB4 were studied. The results demonstrated that both hydrogen and butanol fermentation was partially related to growth. When pH value was controlled at 6.0, cells grew well and hydrogen was accumulated rapidly during the initial fermentation phase (0~16 h). However, clostridial metabolism was inhibited by the accumulation of organic acids during later fermentation phase. When pH value was at lower value of 4.9, cells grew slowly and metabolic activities were restrained. When pH value was controlled at 5.2, butanol accumulation and hydrogen evolution achieved 12.06 g/L and 5.76 L/L, respectively, which were 11.87% and 15.43% higher than those without pH value control. The kinetic models on cell growth, butanol and hydrogen production in batch fermentation were established, the kinetic coefficient R2 demonstrated the fitting of the models was good. Making comparison among kinetic parameters, constant coefficient, indication of butanol synthesis ability after cells growth ceased, was improved by 105.45%, and constant coefficient, indication of maximum hydrogen production rate was improved by 7.45%, when pH value was controlled at 5.2.

Preparation and Characterization of PLA Nanoparticles

XU Jing WANG Lian-yan; YANG Ting-yuan LIU Yan-hui MA Guang-hui

Chin. J. Process Eng.. 2015, 15(3):  495-500.  DOI: 10.12034/j.issn.1009-606X.215132

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A modified precipitation method was used to prepare poly(lactic acid) (PLA) nanoparticles, and the response surface method applied to optimize the preparation parameters. The results showed that there were three main factors affecting the formation of nanoparticles in the preparation process, amount of PLA, volume fraction of ethanol in oil phase and total volume of oil phase. The mathematical model was established using the response surface methodology, and the optimal conditions were obtained with the aim of minimum average particle size, which were the amount of PLA at 76.82 mg, volume fraction of ethanol in oil phase 40%, and oil phase volume 19.49 mL. The size of PLA nanoparticles prepared under the optimal conditions was 109.1 nm and the PDI value 0.084, which was closer to the predicted value. The PLA nanoparticles were spherical solid particles with good dispersibility and uniform size distribution. The PLA nanoparticles could be phagocytosed by macrophage, and used in later immune experiments.

Establishment and Evaluation of Rat Model of Type 2 Diabetes

HE Chao-qun YANG Ting-yuan WANG Lian-yan; ZHANG Gui-feng QI Feng ZHANG Rong MA Guang-hui

Chin. J. Process Eng.. 2015, 15(3):  501-505.  DOI: 10.12034/j.issn.1009-606X.215139

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Animal model of type 2 diabetes mellitus was induced by high-glucose and high-fat diet combined with low-dose streptozotocin for partial destruction of pancreatic b cells. The rats in model group were intraperitoneally injected with streptozotocin (30 mg/kg) after feeding with high-glucose and high-fat diet for 4 weeks. The value of fasting blood glucose greater than 13.8 mmol/L was 86.7% after the injection for one week, and remained stable in 8 weeks. Glucose tolerance test showed that glucose tolerance was impaired in the model group. The hypoglycemic effect of model group was significant after subcutaneous injection of Exenatide (50 mg/kg), after 3 h the glucose level fell by 38.2% compared with the initial level, showing model rats responded well to Exenatide. The rats were sacrificed to harvest the pancreas for pathological examination in the 13th week, the results showed that part of the islet b cells of model rats was destroyed. The method could be used for pharmacodynamic study in related research.

Synthesis and Antibacterial Performance of Didodecyl g-Biquaternary Ammonium Salt

CHEN Ping LI Wen-yu YAO Li-rong CHENG Han-fei ZHANG Wen-yi

Chin. J. Process Eng.. 2015, 15(3):  506-510.  DOI: 10.12034/j.issn.1009-606X.215111

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Didodecyl g-biquaternary ammonium salt (DBAS) was synthesized from di-methyl-dodecylamine and epoxy chloropropane by one-step processs. The effects of DBAS dosage, pH value, water temperature and antibacterial time on the sterilization efficiency of heterotrophic bacteria were investigated. The results showed that its sterilization rate was above 90% in 10 h when the dosage was 10 mg/L, pH value from 6 to 9 and water temperature from 25℃ to 45℃. The main anti-bacterial mechanism was that by adsorption, netting and bridging, heterotrophic bacteria were flocculated with DBAS, which made local drug concentration increase to cause the death of bacteria. Both positively electricity quaternary ammonium N+ groups and ?OH made DBAS in water adsorb to the surface of heterotrophic bacteria more easily. Two hydrophobic groups of ?C12H25 and the hydrophilic groups penetrated into the lipid and protein layer inside the membranes of heterotrophic bacteria cells, modified them, and killed heterotrophic bacteria finally.

Electrochemical Behavior of La-doped LiFePO4/C Cathode Materials for Lithium Ion Batteries

WANG Shan YANG Hai-tao ZHANG Li-bo XU Hong-liang SHI Li-li

Chin. J. Process Eng.. 2015, 15(3):  511-517.  DOI: 10.12034/j.issn.1009-606X.215179

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Alien atom was used to obtain a series of LiFe1-xLaxPO4/C (x=0, 0.002, 0.005, 0.01, 0.015) cathode materials with the aim of investigating the influence of participation of La on the electrochemical behavior of LiFePO4/C. Combination of X-ray diffractometer, scanning electron microscope equipped with energy dispersive spectrometer and high resolution transmission electron microscope was applied. The results show that all the La-doped LiFePO4/C samples are olivine type crystals, La ion is sufficiently introduced into the network, and every element is well homogeneously distributed. There are many pore spaces on the surface of particles. The content of carbon in the prepared cathode materials remains 13.6% calculated by TGA/DTA curves, and the particles are wrapped by a uniformly and continuous carbon layer with the thickness of about 2 nm. Similarly, the content of Fe2P also keeps the same basically in all the cathode materials as a result of the similar ratio (2.35) of peak intensity at 36.5o and 37.1o from XRD. The increasing trend is most pronounced at doped 0.005 which presents the highest initial discharge capacity of 163 mA×h/g, lowest charge transfer resistance of 5.52 W, superior diffuse ability of lithium ion (10-11 cm2/s) and the best capacity retention current rate of about 93% after 50 cycles at 0.1 C.

Effect of Acidity Coefficient of Molten Slag on Properties of Slag Fiber

DU Pei-pei LONG Yue LI Zhi-hui ZHANG Liang-jin ZHANG Yu-zhu

Chin. J. Process Eng.. 2015, 15(3):  518-523.  DOI: 10.12034/j.issn.1009-606X.215031

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Slag fiber was prepared with centrifugal spinning apparatus by adjusting the acidity coefficient of molten blast furnace slag with iron ore tailing. The results show that with the increase of acidity coefficient, the diameter, slag ball content and moisture content of slag fiber increase. When the acidity coefficient is 1.4, the fiber diameter increases significantly, being over standard range. When the acidity coefficient is between 1.0 and 1.25, and the content of slag ball is lower, the quality of fiber is better. When the acidity coefficient is between 1.15 and 1.3, the moisture content of fiber changes little and remains at about 0.66%, its tensile strength and toughness are better. In adjusting the viscosity of quenched slag for preparation of the fiber at appropriate acidity coefficient, the coefficient should be controlled between 1.0 and 1.4 on the premise of fiber forming conditions.

Preparation and Performance of a USY Molecular Sieve Based Hydrocracking Catalyst for Fischer-Tropsch Synthesis of Wax

WU Jian-min SUN Qi-wen ZHANG Zong-sen PANG Li-feng YANG Jun-hua

Chin. J. Process Eng.. 2015, 15(3):  524-529.  DOI: 10.12034/j.issn.1009-606X.216163

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Hydrocracking catalyst for Fischer-Tropsch synthesis of wax was prepared by impregnation method with Ni/W metals on amorphous SiO2-Al2O3 support modified by USY sieve and characterized. The active phase and activity evaluation of sulfide catalyst were also studied. The results indicate that active metal components disperse on the support with high dispersion, and the catalyst with mesoporous structure has higher specific surface area and adsorption capacity. There exist three reduction peaks on the surface of catalyst at 340, 548 and 870℃, which represent NiO?Ni, W6+?W4+ and W4+?W2+ or W, respectively. Meanwhile, FT-IR spectra show that the species of NiWS, WS2 and NiSx exist on the surface of sulfide catalyst. The layer number of WS2 slabs is the important factor to determine the catalytic activity of catalyst. It is induced that alkene has higher hydrogenation activity. Alkane is cracked and isomerized to small molecule alkene, some of which may be in intermediate transition state for farther formation of the small molecule alkane during the hydrocracking and isomerization. At the reaction temperature of 370℃, pressure of 6.4 MPa, hydrogen/wax volume ratio of 800:1 and space velocity of 2.5 h-1, the wax conversion rate maintains almost 50%, and the diesel selectivity almost 90%. Ni/W metals supported on USY/SiO2-Al2O3 can obtain a relative balance of hydrogenation and cracking, thus the catalyst can assure higher wax conversion rate and diesel selectivity.

Effect of Silica Particle Size on Dielectric Properties of SiO2/Epoxy Composite

WU Rui-wen ZHANG Dong-hai WANG Hao-sheng CHEN Yun LI Wen-hui CHEN Yun-fa

Chin. J. Process Eng.. 2015, 15(3):  530-535.  DOI: 10.12034/j.issn.1009-606X.215176

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SiO2/epoxy composite was prepared with silica microspheres at different diameters as filler, which would be used in ultra high voltage DC transmission system. The effect of silica particle size on dielectric properties of the composite was studied by measuring DC volume resistivity, relative dielectric constant and dielectric loss tangent. The role of interface between silica microspheres and epoxy matrix was investigated using SEM and dynamic mechanical analysis. The results indicate that silica microspheres can significantly enhance the dielectric properties of the material. The composite with 100 nm SiO2 filler shows the best results. Its glass transition temperature and DC volume resistivity increase from 104.9℃ to 106.4℃ and 1.87′1017 Ω×cm to 3.24′1017 Ω×cm, respectively, while its relative dielectric constant decreases from 10.99 to 4.92.

Synthesis of Nitrogen-doped Porous Carbon Material with Chitosan by Soft Template Method

FENG Miao-na GAI Jian-nan ZHAO Guo-ying GAO Hong-ling ZHANG Suo-jiang

Chin. J. Process Eng.. 2015, 15(3):  536-540.  DOI: 10.12034/j.issn.1009-606X.215148

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The porous carbon material was synthesized from amphiphilic copolymer pluronic F127 as soft template and protonated chitosan solution as raw material, and the effects of pH value of solution and carbonization temperature on its pore structure, specific surface area and CO2 adsorption capacity were examined. The result showed that the highest specific surface area of porous carbon material reached 457 cm2/g, its highest nitrogen content was 7.60%, and its highest surface nitrogen content 8.45% in the form of pyridine. Its highest CO2 adsorption capacity reached 80.8 mg/g, and the adsorption efficiency was up to 0.274 mg/cm3.