Table of Content

20 April 2014, Volume 14 Issue 2

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流动与传递

Pressure Characteristics in Pulse Cleaning System of Rigid Ceramic Filter

YANG Liang JI Zhong-li LAI Tong

. 2014, 14(2):  181-188. 

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The dynamic pressure characteristics at different positions of pulse cleaning system were measured by high frequency dynamic pressure sensor. The effects of cleaning pressure and diameter of nozzles on pulse cleaning performance were examined. Both design proposals for the subject and filtration to verify this research conclusion were proposed. The results show that there is significant difference of pulse cleaning performance with the same diameter nozzles, the difference of pulse jet nozzles performance increases when cleaning pressure increases, the pulse cleaning intensity decreases when the nozzles diameter increases. The static pressure along cleaning direction gradually increases. By decreasing the diameter of nozzles along the pulse jet direction, the pulse cleaning effectiveness can be improved. The ratio of sectional area of nozzle (s) to sectional area of pulse jet pipe (S) is significant for pulse cleaning. In this research, the best ratio s/S is from 45% to 55%.

Numerical Simulation on Separation of Solid with Liquid and Sedimentation of Red Mud in a Flat Bottom Thickener

LI Mao LI Qiu-long ZHOU Tian LEI Bo ZHOU Jie-min ZHOU Chenn-qian

. 2014, 14(2):  189-196. 

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The solid-liquid separation process in an alumina red mud flat bottom thickener with the diameter of 40 m was simulated using the commercial CFD software Fluent and combining the simplified 3-D Eulerian two-phase model, realizable k-e turbulence model and SIMPLE algorithm. The flow patterns and solid red mud distribution in the thickener were analyzed and the arrangements for the overflow weir and feed inlet for feedwell proposed. The simulation results were verified by field measurements. Further simulation was carried out based on the optimum proposal. Combined with the self-defined evaluation criteria, the obtained results indicated that the solid concentration of overflow was decreased by 84.3% when the overflow weir was removed. And the fluid volume fraction lying in 60~64 g/L in the feedwell was increased from 3.70% to 14.36% after adopting the self-sucking jet pipe in the feed pipe, which could elevate the homogeneity of solid distribution in the feedwell, and enhance the sedimentation efficiency in the red mud thickener.

Effects of Collisional Parameters of Rough Particles on Simulation of Gas-Solid Flow in a Bubbling Fluidized Bed

LU Bing ZHAO Yun-hua ZHONG Ying-jie

. 2014, 14(2):  197-203. 

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A two-fluid model based on the kinetic theory of rough particles was used to study the effects of collisional parameters on the flow behaviors of gas and particles in a bubbling fluidized bed. It was found that increasing the friction coefficient or decreasing the normal restitution coefficient led to more heterogeneous distribution of particles, larger expansion of the bed surface and more intense fluctuation of gas pressure drop. The time-averaged gas-solid flow fields predicted with a proper friction coefficient agreed well with the experimental data, and the friction coefficient was recommended at 0.3~0.6 for the poppy seeds. But the variation of normal restitution coefficient did not change the overall time-averaged flow fields, so its value was less sensitive than the friction coefficient. The tangential restitution coefficient had comparatively much weaker impact on both the dynamic characteristics of the bubbling fluidized bed and the time-averaged gas-solid flow fields.

Impact of Baffle Space Height on the Helical Baffle Double-pipe Heat Exchanger

WU Jing-qiu ZHU Dao-Fei WANG Hua

. 2014, 14(2):  204-210. 

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Heat transfer performance and flow resistance of shell side of the double-pipe heat exchanger with helical baffle were investigated by using CFD numerical simulation software. 5 heat exchangers with the helical baffle at the helical angle of 40o, and baffle space heights of b, 3b/4, b/2, b/4 and b/8 (b refers to the helix pitch) were simulated, and the influence of baffle space height on fluid flow and heat transfer of the shell side was examined. The results indicated that under the same volume flow rate, the heat transfer per unit area, heat transfer coefficient and friction factor increased with the increase of baffle space, but the pressure gradient decreased with the increase of baffle space. The heat exchange coefficient of heat exchangers with partition height of b, 0.75b and 0.5b was enhanced over 7.83, 3.68 and 3 times than that with partition height of 0.125b, and the pressure drop reduced by 98%, 97% and 95%, but the resistance coefficient was enhanced over 34, 15.3 and 5.3 times, respectively. In order to enhance the comprehensive heat exchange of shell side of single-tube heat exchanger with helical baffle, the partition height should be between 0.5b and 0.75b.

Coupled Numerical Simulation on the Flow and Temperature Fields of Molten Steel Pool in a Twin-roll Strip Caster

DONG Jian-hong WANG Nan CHEN Min

. 2014, 14(2):  211-216. 

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Based on CFD software Fluent, a three-dimensional finite-volume model was established, and flow and temperature fields in a molten steel pool of a twin-roll strip caster were simulated. The basic characteristics of flow and temperature fields were analyzed, and the effects of delivery system, outlet angle of feeding device, casting speed, and overheating and cooling conditions on the flow and temperature fields investigated for AISI304 stainless steel casting. The results showed that the turbulent kinetic energy had the maximum value of 0.0175 J/kg and temperature gap was within 20 K at the surface when the casting system combined with submerged nozzle, multi-hole feeding device, flow guiding device and distributing device was used under the conditions of feeding inlet submerging in the distributing device pool, outlet upward angle of feeding device at 15°~18° and steel casting speed 60~80 m/min. Meanwhile, over 0.6 mm solidified shell stably formed between the pool and casting roll contacting surface.

Mathematical Simulation on the Heat Transfer and Solidification Process of Secondary Cooling in Bloom Steel Continuous Casting

XIA Yun-jin FAN Ding-dong LI Jie

. 2014, 14(2):  217-222. 

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The heat transfer and solidification of secondary cooling zone in bloom continuous casting were simulated based on a fluctuated cooling approach-improved (FCA-I), and the three simulation methods, monotonic cooling approach (MCA), fluctuated cooling approach (FCA) and FCA-I, were compared. The results show that the bloom surface temperature before straightening and liquid core length calculated by the three methods have not much difference with the measurements, but FCA-I is more accurate, which can real-time predict the distribution of bloom surface temperature and the liquid core length change with casting speed. FCA-I not only retains the advantages of FCA which can accurately reflect the actual temperature change of foot-roller, but also overcome the shortcomings of FCA which is difficult to adapt to the changing of casting speed. The relationship between the solidification time (t) and shell thickness (dshell) in mold and secondary cooling zone calculated by FCA-I are regressed as dshell=19.62t1/2-2.52 and dshell=29t1/2, respectively, the simulation results basically agree with literatures.

Influential Factors on Dynamic Characteristics of Three-phase Fluidized Bed

LI Hong-li LI Yang-dong LI Deng-xin YIN Chun-sheng

. 2014, 14(2):  223-228. 

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A series of conductivity at different measuring holes in a three-phase fluidized bed were measured by using conductance probe measurement technique, taking glass beads, gold concentrate and gold cyanidation tailing with different diameter particles as solid phase, air as gas phase, and different viscosity liquids as liquid phase. Through calculation, the effects of particle size (dp), density (r), mass (q), superficial gas velocity (Ug) and liquid viscosity (ml) on phase holdups were studied. The results showed that with increasing of dp of glass beads from 0.05 to 0.15 mm, local gas holdup (eg) increased 2%~3%, and local solid holdup (es) decreased 2%~4%. With increasing of r, both es and eg became smaller, and vice versa. With increasing of q, eg decreased, but es increased, with each addition of 100 g glass beads, es increased about 1.5%, eg decreased about 2.5%. With increasing of Ug, both eg and es increased. With increasing or decreasing of ml, eg and es constantly increased or decreased.

Experimental Investigation on Solid-Liquid Suspension in a New Self-aeration Monolayer Multiphase Stirred Tank

HAO Hui-di CHENG Tian-qi QIN Pei-pei ZHU Na LEI Jian-yong ZHAI Tian

. 2014, 14(2):  229-233. 

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A new self-made tornado flow stirred tank was used to carry out experiments without ventilation, the relationship of critical suspension rotational speed (Nc) with the solid content w, particle density r, and inner diameter (D) of the suspension stirred tank was obtained. Under the same geometrical conditions, the new stirred tank was compared with a standard stirred tank in Nc. The results show that Nc increases with the increase of solid phase fraction j and particle size dp, which is not conducive to good suspension. With the increase of solid particle density, Nc goes up. With the increase of the tank diameter, Nc decreases. An expression for Nc of the new stirred tank is obtained, Nc=6.3dp0.21(gDr/rL)0.45w0.19/D0.55. At the same solid phase fraction, Nc in the new stirred tank is below 30% of that in a standard suspension stirred tank, which means that the particles can be suspended at a lower stirring speed.

反应与分离

Treatment of High Content Manganese-containing Wastewater by O3-H2O2 Oxidation Based on Optimal Redox Potential

LI Tian-xin LIU Xiang WU SAhi-ling GU Wei-min UWIZEYIMANA Herman

. 2014, 14(2):  234-240. 

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Ozonation and H2O2-NaOH advanced oxidation processes were used to treat high content manganese-containing wastewater based on optimal redox potential (ORP). The effects of oxidizer (ozone, H2O2 and NaOH) dosages, and the oxidation kinetics were investigated. Experimental results indicated that the ORP was 296~299.7 mV in the ozonation oxidation, under addition of ozone at 0.13~0.15 g/L in both first and second ozonation oxidation processes, the removal rate of Mn2+ reached 91.57%. The ORP was 12.40~12.80 mV in the H2O2-NaOH oxidation, when the dosages of H2O2 and NaOH were 2.0 and 2.6 g/L respectively, their molar ratio was 0.9:1 and H2O2 was added first, the removal rate of Mn2+ reached 99.31%. The treated wastewater had the Mn2+ concentration of 1.2 mg/L which was lower than the first level standard (2.0 mg/L) specified in the National Wastewater Discharge Standard GB 8978-1996. The oxidation kinetics indicated that the oxidation processes obeyed first order reaction kinetics. The rate constant k was 0.0762 min-1 for the first ozonation oxidation and 0.0822 min-1 for the second one at set ORP, otherwise k was 0.0279 and 0.0508 min-1, respectively. k was 0.4758 min-1 for the H2O2-NaOH oxidation at set ORP, otherwise k was 0.3594 min-1.

Extraction and Separation of Indium and Iron Ions from Synthetic Sulphuric Acid Leaching Solution of Blast Furnace Sludge by Ultrasonic Methods

SHEN Xing-mei LI Liao-sha WU Xing-rong GAO Zhi-fang LV Jia

. 2014, 14(2):  242-246. 

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Probe ultrasound and vibrating-plate ultrasound methods were used to enhance the extraction and separation of indium and iron ions from synthetic sulphuric acid leaching solution of blast furnace sludge. Compared with traditional solvent extraction method, the ultrasonic methods could obtain higher extraction and back-extraction rates of indium ion, shorten extraction and back-extraction time, and improve the efficiency. The results showed that vibrating-plate ultrasound method was suitable for extraction process of indium ion, and probe ultrasound method was appropriate to the back-extraction process. The optimal conditions with two ultrasonic methods to extract and separate indium and iron ions from the synthetic solution were 1 mol/L sulphuric acid and vibrating-plate ultrasound extraction for 1 min, which resulted in 96.5% and 8.5% extraction rates of indium and iron ions, and 2 mol/L hydrochloric acid and probe ultrasound back-extraction for 2.5 min, which resulted in 71.0% and 3.8% back-extraction rates of indium and iron ions, respectively.

Characteristics of Treating Carboxymethyl Cellulose Condensate with Upflow Blanket Filter and Biological Aeration Filter

ZHANG Wen-yi LIU Fang LI Wen-yu FENG Guo-yong LIU Yu-chong ZHU Zheng-wei

. 2014, 14(2):  247-252. 

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Aiming at the problem of acidic condensate treatment, which was generated by using multi-effect evaporation of food additive carboxymethyl cellulose (CMC) wastewater, the combined reactor of upflow blanket filter (UBF) with biological aeration filter (BAF) was adopted for biodegradation. Its technological parameters were investigated with hydraulic loading as control parameter. Based on COD removal, the UBF kinetic model was established. Biological phases in UBF and BAF reactors were also analyzed to reveal the characteristics of CMC condensate. The optimum parameters of UBF-BAF reactor were obtained: hydraulic retention time (HRT) of 24 h in UBF reactor, HRT of 5 h in BAF reactor, temperature 20~40℃, pH value 6.5~7.5, and BAF backwashing cycle 5~7 d. When the influent COD concentration was 2388~4000 mg/L, COD removal rates were up to 84.26% and 80.53% in UBF and BAF reactors, respectively. The effluent water could meet Grade I discharge demands of integrated wastewater discharge standard (GB 8978-2002).

Adsorption of Naphthalene at Low Concentration on Activated Carbon

MEI Lei HE Lu FAN Chui-gang HAO Li-fang LI Song-geng SONG Wen-li

. 2014, 14(2):  253-257. 

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Adsorption performance of naphthalene on activated carbon GH-8 at different temperatures and superficial velocities was studied with a fixed bed reactor. Model parameters were obtained by fitting to Yoon-Nelson model, kYN=0.20 h-1 and kYNt=51.404-0.166T+0.292/u. Mass transfer model was used to predict the length and moving velocity of mass transfer zone. The calculation results showed that the maximum relative deviation between the calculated and experimental values was less than 10%.

过程与工艺

Preparation of Hydrated Sodium Metaborate from Boron Concentrate via Pressure Alkaline Leaching

YIN Bao-wen QIN Shi-yue ZHANG Yi-fei ZHANG Yi

. 2014, 14(2):  258-265. 

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Pressure alkaline leaching was used to prepare hydrated sodium metaborate from boron concentrate in NaOH-H2O system. Orthogonal experiments indicated that the most significant influential factor was NaOH concentration, and order of the factors was initial NaOH concentration > reaction time > mass ratio of liquid to solid > temperature. The effects of initial NaOH concentration, reaction time, temperature, mass ratio of liquid to solid, stirring speed and particle size of ore on leaching of boron were examined. Under the optimal conditions (mass fraction of NaOH of 25%, mass ratio of liquid to solid of 4:1, reaction temperature of 140℃, time of 2 h, stirring speed of 500 r/min and gauge pressure of 0.2 MPa), 95.91% of boron was leached out. Na2O and B2O3 in wet boric sludge could be effectively recycled by three-stage countercurrent slurry washing (washing temperature of 90℃, mass ratio of liquid to solid of 3:1, and time of 1 h), dropping to 0.35% and 0.45%, respectively. Final boric sludge containing 42.91% MgO was good raw material for extraction of Mg. After purification, the leachate was crystallized isothermally at 25~30℃ for 6 h and the crystallization rate reached over 70%. Washed with anhydrous ethanol and saturated sodium metaborate solution and dried under 40℃ for 12 h, reulting crystal was analyzed by XRD and proved to be NaB(OH)4, its purity was nearly 90%.

Effect of Mould Rotation on Distribution of Elements in Steel Ingot in Electroslag Remelting

CHANG Li-zhong SHI Xiao-fang CONG Jun-qiang WANG Run-xi LI Tao

. 2014, 14(2):  266-272. 

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A new electrosalg furnace with mould rotation was designed, and the effects of mould rotation speed on element segregation degree were studied. Experiment results showed that when the rotation speed were 0~28 r/min, the distribution of elements in steel ingots became more uniform with the increase of the speed. Statistic segregation degree of C decreased from 0.26 to 0.0545, that of Si from 0.26 to 0.06, that of Mn from 0.17 to 0.03, and that of Cr from 0.2753 to 0.066. The improvement in the solidification structure could be attributed to function of reasonable mould speed which could initiate movement in the slag pool and further increase the uniformity of the temperature in the slag pool. At the same time, movement in the slag pool could also affect the metal molten droplets, the liquid drops scattered randomly in the metal pool. However, the excessive rotation speed would deteriorate the solidification structure. When the rotation speed increased to 35 r/min from 28 r/min, statistic segregation degree of C increased from 0.0545 to 0.097, that of Si from 0.06 to 0.08, that of Mn from 0.03 to 0.076, and that of Cr from 0.066 to 0.16. The main reason was that the excessive rotation speed made the slag pool violent in motion, so as to drive the molten metal pool rotation which would carry off enriched steel surrounding the dendrites in the mushy zone, reduce the solute content in the region and result in the severe element segregation.

Numerical Simulation of Pulverized Coal Combustion in Raceway

ZHANG Shi-yang XUE Qing-guo LIU Jin-zhou SHE Xue-feng WANG Jing-song

. 2014, 14(2):  273-279. 

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A mathematical model of gas-solid flow, heat transfer and pulverized coal combustion in the region of blowpipe-tuyere-raceway bottom was developed. Based on the technological parameters of practical blast furnace, the effects of coal particle size, oxygen enrichment and blast gas temperature on the burnout rate of pulverized coal were studied by numerical simulation. The results indicate that when the coal particle diameter changes from 120 to 70 μm, the burnout rate is increased by 35.928%, when the oxygen content in the blast gas is reduced from 30% to 21%, the burnout rate is decreased by 16.542%, and when the blast gas temperature is increased from 1423 to 1498 K, the burnout rate is raised by only 8.897%. Devolatilization process and oxygen availability are dominant factors for coal burnout. In addition, in examination of the influences of variables on pulverized coal burnout, the simulation region should include blowpipe, tuyere and raceway.

Decomposition of Potassium Feldspar by NaOH Sub-molten Salt Method

WANG Ying GUO Ju-hua HUANG Jin-feng CHENG Hua-dan GUAN Huai-min CAO Ji-lin TONG Yue-jin

. 2014, 14(2):  280-285. 

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High concentration NaOH sub-molten salt was used to decompose potassium feldspar powder. The effects of the particle size, concentration of NaOH, stirring speed, reaction time, reaction temperature and mass ratio of liquid to solid on the dissolution rate of K+ were studied. The optimum reaction conditions were obtained for 100 mm diameter potassium feldspar powder, that is, NaOH initial concentration 60%(w), reaction temperature about 160℃, stirring speed 400 r/min, and mass ratio of liquid to solid 4:1. After 140 min reaction, the dissolution rate of K+ was over 98%(w). The decomposition kinetics of potassium feldspar powder under the reaction conditions was studied. The decomposition rate of potassium feldspar powder was in accordance with the shrinking core model at constant particle size. The reaction was controlled by the internal diffusion through ash layer in the initial stage of reaction. The kinetic constants were estimated, and the apparent activation energy was 110.42 kJ/mol at the temperatures of 80~140℃.

Dehydration Reaction Kinetics of Limonite under Microwave Heating

HAN Lei LI Jie LI Bao-wei HAN Ji-cheng HAN Teng-fei YANG Zhong-yu

. 2014, 14(2):  286-290. 

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The dehydration process of limonite under microwave heating was studied, and the change of mineral phases in limonite analyzed by SEM and XRD before and after removal of crystalliferous water. Then, according to the temperature-rising and weight loss curves, the kinetic parameters of thermal decomposition of crystalliferous water in limonite were calculated by differential method and integral method, the dehydration reaction mechanism of limonite by microwave heating was determined. The results showed that the chemical formula of limonite was 2Fe2O3·3H2O, limonite became hematite after removal of crystalliferous water, and the content of Fe2O3 and SiO2 increased, the grain size of iron ore decreased, mineral phase became relatively pure. The apparent activation energy of dehydration reaction was 17.39~19.33 kJ/mol in 470~650 K, lower than that by conventional heating, which indicated that microwave heating was favorable for lowering the reaction activation energy; and the reaction mechanism accorded with Maple single rule, belonging to the chemical reaction control of random nucleation and then growth.

Combustion Characteristics of Char Particles in Different Controlling Regions

CHEN Ming-lei LI Bao-wei WU Wen-pei

. 2014, 14(2):  291-295. 

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For the complex combustion of char particles in a pulverized coal furnace, mutually coupled thermal models of the gas phase mass and heat transfer and the improved random pore model were set up. The combustion characteristics of char particles in different controlling regions were studied by programming with FORTRAN. The combustion characteristics in the diffusion-chemical reaction kinetics controlling region were analyzed with improved random pore model. The results show that in the diffusion-chemical reaction kinetics controlling region, the micro-pore on the carbon matrix had the O2 concentration gradient, when the conversion rate of char particles reached 0.39, the reaction rate of char particles had a maximum value. During the combustion process, the conversion rate of char particles increased first, and then decreased.

生化工程专栏

Preparation of Uniform Konjac Glucomannan Gel Microspheres by Rotating Membrane Emulsification

LI Xiao-qing GONG Fang-ling; MA Guang-hui

. 2014, 14(2):  296-303. 

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Uniform konjac glucomannan (KGM) gel microspheres were prepared by a combined method of rotating membrane emulsification with chemical cross-linking by using natural KGM. 12%(w) aqueous KGM solution with three viscosities was taken as water phase and mixture of liquid paraffin (LP) and petroleum ether (PE) as oil phase. The effects of emulsifier, water phase viscosity, oil phase composition and rotational speed on the microsphere size and size distributions were investigated. The results showed that the higher the viscosity of KGM solution was, the lower the LP content of corresponding optimal oil phase was. The optimum conditions were obtained as rotational speed at 400 r/min, emulsifier 4%(w) Span 80, volume ratio of LP to PE 5:1 and viscosity of aqueous KGM solution 1548 mPa×s. Under the optimum conditions, the prepared KGM gel microspheres had the uniform diameter of about 70 mm and size distribution index Span<1.0.

Light Attenuation Models and Simulation of Light Regime Characteristics of Chlorella pyrenoidosa Cells

HUANG Jian-ke KANG Shao-feng LI Yuan-guang LI Wei

. 2014, 14(2):  304-311. 

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Different models were used to describe the light attenuation of Chlorella pyrenoidosa cells in the concentration range of 0.06~2.68 g/L. The results showed the Cornet model was the best one to describe and predict the light attenuation. The absorption coefficient of Cornet model (Ea) and scattering coefficient (Es) were determined as 0.0014 and 0.9022 m2/g, respectively. The absorption coefficient of Lambert-Beer model (Ka) and Ea increased with the increase of pigment content, but Es decreased. The pigment content of cells more significantly influenced the degree of light attenuation when the biomass concentration was low. The light regime characteristics of algae cells were calculated based on the integration of CFD and Cornet model of light attenuation. Under the same conditions, the time-averaged light intensity of algal cells within 15 L flat plate photobioreactor was decreased by 35.5%, and frequency of light dark cycle inside the photobioreactor increased by 78.1% compared with those in the 3 L flat plate photobioreactor.

Optimization of the Fermentation Medium for Cellulase Production from Trichoderma reesei Rut-C30 and Its Enzymatic Hydrolysis Characteristics

ZHANG Xiao-yue ZI Li-han; LI Yong-hao ZHAO Xin-qing; BAI Feng-wu

. 2014, 14(2):  312-318. 

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Cheap industrial cellulose was taken as substrate for cellulase production from Trichoderma. reesei Rut-C30. The five-level three-variable central composite design implemented in the package of response surface methodology was adopted to evaluate the effects of industrial cellulose, wheat bran and soy flour on filter paper activity of (FPA) of cellulose. The results show that the optimal formulation of fermentation medium was determined as follows: industrial cellulose 35.62 g/L, wheat bran 19.37 g/L and soy flour 38.49 g/L. Thus, FPA achieved 9.13 IU/mL, which was increased by 72.26% over that without optimization, and the glucosidase activity was also increased by 80.39%. This crude cellulase solution was applied to obtain a hydrolysis yield of 94.68% in the hydrolysis of corn stalk which was pretreated by 2% NaOH for 45 min under 121℃, and the cellulose content of 64.94%.

Selection and Exploration of Different Solvents for Extraction of Microalgae Edible Oil

WANG Lu FAN Xing ZHANG Dong-mei SUN Zhong-liang SU Hai-jia CONG Wei

. 2014, 14(2):  319-323. 

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Microalgae oil was extracted by six solvents commonly used for oil extraction, respectively, with ice bath ultrasonication for 15 min and extraction 8 h. The extraction behavior of microalgae oil with different solvents was studied. The results showed that for extraction of the oil from microalgae powder, n-hexane showed a better effect, resulting in a higher extraction rate of 71.52%, the oil contained 75.86% neutral lipid and 1.63% vitamin E, and the residual rates of protein, chlorophyll and carbohydrate were 55.92%, 61.33% and 78.35%, respectively. For extraction of the oil from microalgae ooze, n-hexane/ethanol mixed solvent showed a better effect, resulting in a higher extraction rate of 68.31%, the oil contained 71.65% neutral lipid and 1.87% vitamin E, and the residual rates of protein, chlorophyll and carbohydrate were 60.56%, 53.27% and 80.20%, respectively.

Synthesis of Water-soluble Quaternary Ammonium Polymer and Its Anti-bacterial Performance of Heterotrophic Bacteria

ZHANG Wen-yi LI Wen-yu FENG Guo-yong LIU Fang YAO Li-rong CHENG Han-fei

. 2014, 14(2):  324-328. 

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Water-soluble quaternary ammonium polymer, poly[oxyethylene (dimethylimino) ethylene-(dimethylimino) ethylene dichloride] (PODEDED), was synthesized by polymerization reaction between tetramethylethylenediamine and bis-(2-chloroethyl)ether as raw materials. The effects of PODEDED dosage, pH value, water temperature and anti-bacterial time on the sterilization efficiency of heterotrophic bacteria were investigated. The result showed that the anti-bacterial rate could reach 99% under the conditions of dosage at 60 mg/L, anti-bacterial time 8~24 h, pH 5~10 and water temperature 30~45℃. The anti-bacterial mechanism was that hydrophobic and hydrophilic groups in long chain alkyl and positive electricity quaternary ammonium N+ groups of PODEDED entered deeply into lipid layer and protein layer of heterotrophic bacteria membrane, leading to destruction of the plasma membrane which controled cell infiltration, and resulting in leakage of intracellular substances and killing of heterotrophic bacteria. PODEDED could be widely used in killing heterotrophic bacteria in various open circulating water systems, sewage treatment and reuse systems.

材料工程专栏

Synthesis of Silicon-containing Arylacetylene Resin Catalyzed by Zinc Powde

SHEN Hao JIANG Xiao-jie ZHOU Yan DENG Shi-feng DU Lei XIA Hong-juan HUANG Fa-rong

. 2014, 14(2):  329-334. 

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Silicon-containing arylacetylene (PSA) resin was prepared by the condensation reaction between diethynylbenzene and dimethyldichlorosilane catalyzed by zinc powder. The structures of PSA resin were characterized. The optimum reaction conditions were obtained as follows: acetonitrile as solvent, amount of zinc overdosed 200%, temperature 80℃ and reaction time 10 h. And the resulting reaction yield reached up to 82%. The curing behavior of PSA resin was analyzed by DSC, and the thermal stability of cured resin by TGA. The results showed that the PSA resin was easily processed and could be cured at the temperature of about 170℃. The cured PSA resin possessed excellent thermal stability. The temperature at 5% weight loss reached 529℃, and char yield of the cured resin at 800℃ under nitrogen was 85%.

Structure and Electrochemical Properties of La-Mg-Ni System Hydrogen Storage Alloy

XU Jian-yi HU Feng WANG Qing-chun LI Xia WANG Rui-fen ZHANG Yin

. 2014, 14(2):  335-339. 

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The hydrogen storage alloy La0.75Mg0.25Ni3.4-xAl0.1Cox (x=0.0, 0.5, 1.0) was prepared by induction smelting. The effect of partial replacement of Ni by Co in the alloy on its structure and electrochemical properties was studied. The results show that the alloy consists of La2Ni7 and LaMg2Ni9 phases and LaNi5 phase of CaCu5 type. The replacement of Ni by Co had a little effect on the activation property of alloy electrodes. The discharge capacity and cyclic stability of alloy electrodes increase first from 316.92 mA.h/g and 61.83% (x=0) to 340.31 mA.h/g and 75.21% (x=0.5), and then decreases to 333.22 mA.h/g and 66.70% (x=1.0) with increasing of Co content. The high rate discharge ability decreases with the addition of Co content. At the discharge current density of 900 mA/g, the high rate discharge ability of alloy electrodes decreases from 62.49% (x=0) to 53.68% (x=1.0). The substitution leads to some increase in the limiting current density and electrochemical impedance spectroscopy. The deterioration of its high rate discharge ability can be ascribed to the synergic effect of electron transfer on the alloy surface and hydrogen diffusion in the bulk of alloy.

Preparation of Calcium-based Composite Sorbent by Hydrolysis of Calcium Carbide and Its Multi-cyclic CO2 Capture Performance

NIU Jia-ning ZHANG Deng-feng JIN Yue JIA Jian-li LI Song-geng LIN Wei-gang

. 2014, 14(2):  340-344. 

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The CaO/Ca12Al14O33 sorbent was prepared by the hydrolysis of calcium carbide. The effects of Ca12Al14O33 content, carbonation temperature and calcination temperature on CaO conversion rate and its cyclic stability were investigated by thermal gravimetric analysis. Multi-cyclic CO2 capture performance of the sorbent was compared with CaCO3 and calcium carbide hydrolysis slag. The sorbent was characterized physically. The results showed that the prepared sorbent exhibited superior CO2 capture performance compared with pure CaCO3 and calcium hydrolysis carbide slag. Ca12Al14O33 played a significant role in preventing the sorbent sintering at high temperatures. CaO conversion rate with the prepared sorbent can be maintained at above 48% after 20 cycles.

Synthesis of Comb Polymer Carboxylic Dispersant and Its Application in Imidacloprid Aqueous Suspension Concentrate

XING Wen ZHOU Yi-fu TIAN Xiao-bin REN Tian-rui

. 2014, 14(2):  345-349. 

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The macromolecular monomer, maleic acid polyethylene glycol ester (MAPEG), was prepared by maleic anhydride (MA) and polyethylene glycol (PEG) as raw materials. Three kinds of comb-style carboxylic dispersants were synthesized with MAPEG, acrylic acid (AA) and methyl methacrylate (MMA) by radical polymerization at different monomer ratios. Application of the dispersants in 600 g/L imidacloprid aqueous suspension concentrate was investigated through determination of flow point, viscosity and Zeta potential. The results showed that the optimal molar ratio of MAPEG:AA:MMA was 1:8:2. When the dosage of dispersant was 6%(w), the minimum viscosity of suspension was 600 MPa×s. The suspension rates before and after heat storage were 93.7%±0.22% and 92.3%±0.12%, and the particle size 3.26 and 3.88 mm. The effect of dispersion was equal to commercial Huntsman 2500 product.

Synthesis of Samarium-doped ZnO by Hydrothermal Method and Its Gas Sensing Properties towards Dimethylamine

SONG Jin-ling REN Wen-qiang BAO Shuang-feng ZHANG Yin GUO Guan-ming CAI Ying

. 2014, 14(2):  350-353. 

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The hexagonal wurtzite ZnO powder and samarium-doped ZnO powder (ZnO:Sm) were prepared by environment-friendly hydrothermal method without using any assisting agents. The gas sensing results show that the ZnO:Sm material exhibits better sensitivity towards dimethylamine. Its sensitivity increases with increasing of dimethylamine concentration. When the concentration of dimethylamine is 1.00′10-4, the sensitivity reaches 63.97. Moreover, in the atmosphere of trimethylamine, the sensitivity of ZnO:Sm towards dimethylamine exhibits excellent selectivity. The response time is about 6 s, and the recovery time about 19 s.

综述

Approaches for Enhancing Oral Bioavailability of Peptides and Proteins

WANG Dong WANG Lian-yan; CHANG Xiu-lian YANG Ting-yuan MA Guang-hui

. 2014, 14(2):  354-360. 

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The approaches for enhancing oral bioavailability of biomacromolecules, such as peptides and proteins, including chemical modification, absorption enhancers, mucoadhesive systems, liposomes and nano-microparticles are comprehensively reviewed, and the status of these approaches and their relative merits analyzed, focusing on the status of nano-microparticles. Finally, it is pointed out that on the basis of nano-microparticles, analyzing and designing all aspects of drug release and absorption systematically and personally, oral drug delivery system of peptides and proteins for clinical applications is expected to construct.