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Table of Content
05 May 2013, Volume 64 Issue 5
    Experimental study and mechanism analysis for high-temperature thermal stability of ternary nitrate salt
    PENG Qiang, YANG Xiaoxi, DING Jing, WEI Xiaolan, YANG Jianping
    2013, (5):  1507-1512.  doi:10.3969/j.issn.0438-1157.2013.05.001
    Abstract ( 1356 )   PDF (956KB) ( 498 )  
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    High-temperature thermal stability of ternary nitrate salt(53%KNO3-40%NaNO2-7%NaNO3)in air and nitrogen is investigated by mass loss ratio, NO2- content of molten salt and thermo-gravimetric analysis.The results show the upper limit of operation temperature is 773 K in air for the ternary nitrate salt and the deterioration will appear at higher temperatures, while the thermal decomposition begins at 723 K and proceeds slowly in nitrogen.According to the thermodynamics and kinetics of molten salt, the thermal decomposition and oxidation of sodium nitrite of the ternary nitrate salt occur below 773 K in air, while the reaction for the ternary salt in nitrogen is the thermal decomposition of sodium nitrite below 723 K.Diffusion of oxygen and decomposition reaction of nitrite follow the first order reaction kinetics when the oxygen content is constant.
    Solubility of CO2 in molten poly(ethylene terephthalate)
    ZHONG Hua, SUN Shaojun, XI Zhenhao, LIU Tao, ZHAO Ling
    2013, (5):  1513-1519.  doi:10.3969/j.issn.0438-1157.2013.05.002
    Abstract ( 1838 )   PDF (1441KB) ( 382 )  
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    The solubility of CO2 in poly(ethylene terephthalate)(PET) was studied using magnetic suspension balance (MSB) combined with high-temperature high-pressure view cell.The former gives apparent solubility and the latter presents swelling volume through direct observation in the presence of CO2,which is necessary to correct the gas buoyancy acting on PET melts in the MSB measurement.The effects of temperature and pressure on the swelling ratio and CO2 solubility in traditional and modified PET melt were analyzed.The results show that both swelling ratio of PET and solubility of CO2 decrease as temperature increases and increase with pressure.However,the swelling ratio increases slowly and approaches a plateau region under higher pressure.Compared with traditional linear PET,the modified PET displays lower swelling ratio and solubility.Solubility of CO2 in PET melt is in an order of magnitude of 10-2 g CO2·(g PET melt)-1 under 4-6 MPa in the temperature range of 250-280℃.CO2 solubility in PET melt agrees well with Henry’s law in the pressure range of 1-6 MPa.Heat of solution is obtained using the least-square method.
    Measurement and prediction of excess molar enthalpies of ternary working solutions 1-butyl-3-methylimidazolium dibutylphosphate + methanol/ethanol + water
    ZHANG Xiaodong, CHANG Renjie, ZHAO Zongchang
    2013, (5):  1520-1525.  doi:10.3969/j.issn.0438-1157.2013.05.003
    Abstract ( 1443 )   PDF (816KB) ( 352 )  
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    The excess molar enthalpies of binary and ternary working solutions containing ionic liquid, 1-butyl-3-methylimidazolium dibutylphosphate,(1)+ CH3OH(2)/C2H5OH(2)/H2O(2)and(1)+ CH3OH(2)/C2H5OH(2)+ H2O(3)were measured with an adiabatic calorimeter at 298.15 K under the normal atmospheric pressure.The experimental excess molar enthalpies of binary working solutions were correlated with non-random two liquid(NRTL)activity coefficient model, and the binary interaction parameters were obtained.The average relative deviations between the correlated excess molar enthalpies and the experimental values for three binary solutions are 1.81%,1.44% and 0.72%.For the excess molar enthalpies of two ternary solutions predicted based on the binary interaction parameters, the average relative deviations between the predicted and the experimental excess molar enthalpies are 2.31% and 2.49%.The excess molar enthalpies for the binary solutions and the ternary solutions are negative in the whole range of IL concentration, so the mixing processes of[bmim] with water and methanol or ethanol are exothermic, which is one of the basic property of working solution in absorption cycles.
    Influence mechanism of nitric acid on thermal stability of nitrobenzene
    RUAN Jifeng, SUN Jinhua, GUO Song, PING Ping
    2013, (5):  1526-1531.  doi:10.3969/j.issn.0438-1157.2013.05.004
    Abstract ( 1534 )   PDF (658KB) ( 359 )  
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    The influence of nitric acid on the thermal stability of nitrobenzene was studied.The thermal behavior and chemical thermodynamic parameters of pure nitrobenzene and its mixtures with nitric acid were analyzed by utilizing a CALVET heat flux calorimeter, C80.The kinetic parameters of chemical reaction, such as activation energy, frequency factor and heat of reaction, were calculated based on the experimental data of C80.Based on these parameters and the Semenov thermal explosion theory, the self-accelerating decomposition temperature of samples was calculated and compared.A GCT gas chromatography-time of flight mass spectrography was used to analyze the thermal decomposition of pure nitrobenzene at high temperature.The thermal decomposition mechanism of nitrobenzene and its mixture with nitric acid was proposed.
    Characteristics of heat and mass transfer in direct evaporative cooling process in different temperature ranges
    CHEN Yao, YIN Yonggao, ZHANG Xiaosong, WANG Geng
    2013, (5):  1532-1540.  doi:10.3969/j.issn.0438-1157.2013.05.005
    Abstract ( 1585 )   PDF (1254KB) ( 446 )  
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    The characteristics of heat and mass transfer between the air and water in a direct evaporative cooling process will be different in different temperature ranges.In this study, experiments of a novel direct evaporative cooling counter-flow system were carried out with a psychrometric chamber in normal and lower temperature ranges.Experimental results show that a cooling efficiency of 88% can be achieved, demonstrating that the alumina foam ceramic is a promising packing material for the evaporative cooling system.The comparison of characteristics between normal and lower temperature ranges shows that direct evaporative cooling process in the lower temperature range is more sensitive to driving forces.In the temperature range from 0℃ to 15℃, the relationships between temperature difference and cooling efficiency, pressure of water vapor and air humidity difference, enthalpy difference and enthalpy efficiency were analyzed and determined.Exergy analysis was used to evaluate the energy effectiveness of direct evaporative cooling process in the lower temperature range, the improvement on performance, and application potential.
    Periodic laminar flow and heat transfer in square channel
    WANG Jiansheng, XU Yong
    2013, (5):  1541-1548.  doi:10.3969/j.issn.0438-1157.2013.05.006
    Abstract ( 1245 )   PDF (4651KB) ( 467 )  
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    A numerical investigation is conducted to examine laminar periodic flow and heat transfer characteristics in a square channel fitted with 45? inclined baffle inserted periodically in the channel.Air is the working fluid with the flow rate in terms of Reynolds number based on the channel hydraulic diameter ranging from 100 to 1000.The utilization of the 45? inclined baffles is to create counter-rotating vortex flows having a significant influence on the flow laminar intensity, enhancing heat transfer in the channel.Effects of different pitch ratios(PR=L/H)with a baffle height ratio(BR=b/H)of 0.2 on heat transfer and pressure loss in the channel were examined.The results show that the baffles create pair of vortex flows, inducing impingement flows on a side and the upper and lower walls and increasing heat transfer rate over the test channel substantially.An analysis on the averaged Nusselt number ratio, friction factor ratio and thermal enhancement factor with the change of pitch ratio and Reynolds number is used for establishing the corresponding criterion correlation.The computation reveals that the optimum thermal performance enhancement factor of about 3.0 is found at PR=0.5.
    Characteristics of VOC mass transfer from wood furniture surface
    SONG Wei, KONG Qingyuan, LI Hongmei
    2013, (5):  1549-1560.  doi:10.3969/j.issn.0438-1157.2013.05.007
    Abstract ( 1517 )   PDF (1667KB) ( 428 )  
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    Volatile organic compound(VOC)emission from wood furniture surface is a complex process of mass transfer with negative environmental effects.To have a clear picture of mass transfer characteristics, a new fully analytical model was established by using Laplace Transform, which comprehensively considered two key mechanisms of mass transfer(diffusion and convection), resistances of changing climate chamber concentration, background concentration and concentration of air inflow, and was applicable to simulating unventilated or ventilated condition, e.g.,predicting the concentration in climate chamber or furniture, evaluating the mass transfer rate or amount of emission and estimating the time for climate chamber concentration to reach an acceptable level.Then this model was analyzed to propose a convenient and rapid experimental method for simultaneously determining three significant mass transfer parameters of target VOC:emittable concentration ρ0, diffusion coefficient δ and partition coefficient β, by making use of the process concentrations in a ventilated climate chamber.On one hand, a linear relationship was established between elapsed time and logarithm of difference between process concentration and equilibrium concentration, and its slope and intercept were the simple functions of δ and β.By data fitting and analysis, the slope and intercept were easily obtained as well as δ and β.On the other hand, a relationship was also established between β and ρ0.Combined with the known β,ρ0 could be easily further obtained too.In experiments,this method was used to study ρ0, δ and β of formaldehyde and TVOC mass transfer from a piece of wood furniture made of medium density fiberboards, urea formaldehyde resin adhesive, veneer and polyurethane paint, which showed a coefficient of variation less than 5% between experimental results and calculation according to a reference treatment method by making use of mass transfer process concentration in an unventilated chamber, and effectively avoided potential troubles, such as negative pressure possibly caused by sampling in an unventilated chamber.The predicted results of climate chamber concentration in either unventilated or ventilated condition based on determined parameters and a numerical calculating model were in agreement with corresponding experimental data.In conclusion, both the proposed model and method are accurate enough to predict or determine mass transfer characteristics of VOC emission from wood furniture surface.
    High precision approximate solution of transient heat-conduction time function of wellbore heat transfer
    CHENG Wenlong, NIAN Yongle
    2013, (5):  1561-1565.  doi:10.3969/j.issn.0438-1157.2013.05.008
    Abstract ( 1261 )   PDF (937KB) ( 313 )  
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    Transient heat-conduction time function is a crucial function for wellbore heat transfer in the process of steam injection for heavy oil production.All of the common transient heat-conduction time functions and related approximate solutions ignore wellbore heat capacity and other properties, but the heat capacity has obvious effect on the heat transfer in wellbore, especially in short time, so the error is large in the early days of steam injection.Based on a novel transient heat-conduction time function considering the effect of heat capacity of wellbore, a new approximate solution is obtained by the numerical fitting method and compared with those traditional approximate solutions, which only give good results in long time.The new approximate solution presents higher precision all the time, especially in the early period of steam injection.It is shown that the new approximate solution of transient heat-conduction time function is simple in form and easy to use, so it has good practicability in engineering with wider applicability.
    Quenching boiling of aqueous suspensions with carbon nanotubes
    LI Danyang, ZHU Yuanzheng, ZHANG Liang, FAN Liwu, XU Xu, YU Zitao, HONG Ronghua, HU Yacai
    2013, (5):  1566-1572.  doi:10.3969/j.issn.0438-1157.2013.05.009
    Abstract ( 1268 )   PDF (1647KB) ( 382 )  
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    In order to examine the combined effects of surface roughness and concentration on pool boiling of nanoparticle suspensions, an experimental study on quenching processes of aqueous suspensions with carbon nanotubes(0.1% and 0.5%)was conducted using nickel-plated copper spheres with surface roughness of Ra0.5 and Ra12.5.Quenching curves were acquired directly and boiling curves during the quenching processes were calculated based on a lumped capacitance model.It is shown that increase in both concentration of suspensions and surface roughness expedites quenching speed and enhances critical heat flux.Increase in surface roughness decreases the time duration of nucleate boiling and less film boiling time is primarily due to increased concentration.The combined effects of surface roughness and concentration suggest that quenching objects are utilized with rough surfaces in nanoparticle suspensions of relatively high concentration so as to significantly shorten the quenching time for engineering applications.
    Flow pattern transition criteria of flow boiling in confined mini/micro-channel
    LIU Xin, ZHANG Shusheng, CHENG Lin, CHANG Wei
    2013, (5):  1573-1579.  doi:10.3969/j.issn.0438-1157.2013.05.010
    Abstract ( 1158 )   PDF (946KB) ( 365 )  
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    The effect of channel size on bubble motion characteristics under mini/micro-scale condition is analyzed theoretically.The comparison between channel width and bubble departure diameter indicate that when the former is smaller than the latter, the flow pattern of confined bubbly flow will occur, the flow features of which is further analyzed.On this basis, traditional flow patterns in confined mini/micro-channel are subdivided and flow pattern transition criteria are derived.The prediction of the theoretical model agrees well with corresponding experimental data.The analysis on characteristics of the transition criteria shows an apparent postponement of transition for flow boiling in mini/micro-channel than that under adiabatic conditions.Moreover, for flow boiling under the same heat flux and mass flux conditions, the flow pattern transition may occur earlier with the decrease of channel size.
    Effect of inclination angle of heating surface on bubble growth-condensation behavior during subcooled flow boiling
    XU Chao, GAO Puzhen, LI Shaodan, GAO Feng
    2013, (5):  1580-1585.  doi:10.3969/j.issn.0438-1157.2013.05.011
    Abstract ( 1146 )   PDF (845KB) ( 403 )  
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    By using a high speed camera, the bubble growth-condensation behavior under subcooled flow boiling in an inclined single-side heated rectangular channel was investigated experimentally.The influences of inclination angle on growth-condensation rate of bubbles, their distribution, maximum diameter and growth time were discussed.The results show that with same inlet parameters, the bubble maximum size and lifetime are proportional to the inclination angle; for different angles, the bubble size and growth time follow the 0.5 power law.In dimensionless form of Zuber model, in the growth region, the growth rate increases with increasing angle, but in the condensation region, there is no obvious relationship between the condensation rate and inclination angles.
    Three-dimensional numerical simulation of multiple bubbles rising and interaction with lattice Boltzmann method
    SUN Tao, LI Weizhong, YANG Baicheng, ZHU Puqing
    2013, (5):  1586-1591.  doi:10.3969/j.issn.0438-1157.2013.05.012
    Abstract ( 1722 )   PDF (3247KB) ( 401 )  
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    Multiple bubbles rising and interaction in a quiescent viscous incompressible fluid was simulated with three-dimensional lattice Boltzmann free energy model with a large density ratio.In order to avoid numerical instability caused by a large density ratio, eight-point and eighteen-point difference schemes were used to calculate the first and the second order derivative 1586Φ and 15862Φ, respectively.The results of simulation presented the effects of initial bubble size and location on the flow field induced by rising bubbles and on the evolution of bubble shape.For multiple rising bubbles with the same size, the trailing bubble was influenced by the wake of the leading bubble.The strength of influence depended on both the distance between bubbles and the relative position.With the increase of distance, the strength decreased gradually.For multiple bubbles with different sizes, however, the larger bubble always strongly affected the smaller one at any initial size and location.
    Fluidized bed combustion of seaweed biomass particles
    WANG Shuang, JIANG Xiumin, WANG Qian, JI Hengsong
    2013, (5):  1592-1600.  doi:10.3969/j.issn.0438-1157.2013.05.013
    Abstract ( 1841 )   PDF (1785KB) ( 474 )  
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    Fluidized bed combustion experiment of two seaweed particles(Enteromorpha clathrata and Sargassum natans)was carried out in a bench-scale combustor.When seaweed particles were fed into the fluidized bed, dehydration and release of volatile matter happened.Devolatilization and burning of volatile matter of seaweed particles during fluidized bed combustion happened in about 1 min, followed by combustion of char.Combustion of char accorded with the shrinking core model in which carbon nucleus burned layer by layer from outside to inside and ash layer radius remained almost constant.As volatile matter was released at the beginning of combustion, Sargassum natans particles fractured immediately after they were fed into the fluidized bed.SEM analysis was used to study the cross-sections of Enteromorpha clathrata particles and their chars collected at different combustion periods.During the combustion process of Enteromorpha clathrata particles, internal porosity of particles increased gradually.The micro-pore surface became rougher.By feeding a few seaweed particles at a time,combustion of two seaweed particles(Enteromorpha clathrata,Sargassum natans)was also studied in the fluidized bed.During combustion of Enteromorpha clathrata particles, relative concentration of NOx increased, while relative concentration of CO decreased.The SO2 and NOx released from Sargassum natans particles were more than those from Enteromorpha clathrata particles.CO concentration also decreased with increasing bed temperature.Increasing bed temperature intensified heat transfer in the combustor. Devolatilization of two kinds of seaweed happened earlier, and burnout time both shortened.Increase of air velocity and bed height facilitated combustion of two kinds of seaweed and shortened their burnout time.
    Influence of viscoelasticity on liquid primary atomization
    HOU Yanbing, TIAN Xiushan, ZHAO Hui, LI Weifeng, XU Jianliang, LIU Haifeng
    2013, (5):  1601-1606.  doi:10.3969/j.issn.0438-1157.2013.05.014
    Abstract ( 1068 )   PDF (964KB) ( 362 )  
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    The influence of viscoelasticity on primary atomization of syrup and syrup polymer solutions was studied experimentally with the coaxial air-blast atomizer.The breakup regimes were divided according to high-speed camera graphs and breakup instability characteristics on the surface of liquid jet were performed.The results proved that primary breakup of the experimental medium could be divided into three regimes, non-axisymmetric oscillation, membrane breakup and fiber breakup.However, the breakup transition Weber number of syrup-polymer was larger than that of syrup solution with the same viscosity.The instability wavelength on the surface of liquid was closely related to air velocity and liquid viscoelasticity, the elasticity parameter Wi was introduced in the instability wavelength theory model that considered the influence of vorticity-layer, and a new equation of instability wavelength was fitted with relevant characteristic parameters.
    Solids flux of pulverized coal of high-pressure and dense-phase pneumatic conveying and ANN simulation
    LU Peng, HAN Dong, PU Wenhao, YUE Chen, CHEN Xiaoping, ZHAO Changsui
    2013, (5):  1607-1613.  doi:10.3969/j.issn.0438-1157.2013.05.015
    Abstract ( 1242 )   PDF (1064KB) ( 380 )  
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    By changing operating conditions, such as conveying pressure P1, total differential pressure ΔPT and fluidizing gas flow rate Qf, and by changing properties of pulverized coal, such as particle size dp, moisture content W and coal category, experimental investigations on solids flux ψ of pulverized coal were conducted on a pilot scale experimental setup of high-pressure and dense-phase pneumatic conveying. Considering the complexity of high-pressure and dense-phase solids-gas flow, artificial neural network(ANN)was introduced based on sufficient experiments.Original BP neural network and two kinds of improved algorithm were used and their simulation and prediction results were compared.The results showed that ψ increased with P1 and ΔPT, and it increased firstly and then decreased with Qf.ψ reduced with the increase of dp and W, and it was also affected by coal category.The two kinds of improved algorithm in BP neural network could successfully simulate and predict ψ of pulverized coal, however, convergence speed and prediction accuracy could not be satisfied simultaneously.The work in this paper can guide the control, operation, simulation and prediction of key characteristic parameters for high-pressure and dense-phase pneumatic conveying system.
    Cluster frequency and existence time in dense transport bed
    ZENG Xin, YANG Shaojun, WANG Shengdian, ZHAO Kai, XU Xiang, XIAO Yunhan
    2013, (5):  1614-1620.  doi:10.3969/j.issn.0438-1157.2013.05.016
    Abstract ( 1136 )   PDF (509KB) ( 281 )  
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    Cluster characteristics(cluster frequency and cluster existence time)were investigated with wavelet analysis in a cold dense transport bed with Geldart B particle using a fiber optic probe.The superficial gas velocities and solids circulating rate were in the range of 8.2-11.2 m穝-1 and 139-530 kg穖-2-1, respectively.The results indicated that large scale clusters were easier to form in the near wall and bottom zone than in the center and the top zone of the riser, respectively.Cluster frequency decreased from center to wall, while cluster existence time increased from center to wall.Cluster frequency increased with increasing superficial gas velocity, while cluster existence time decreased with increasing superficial gas velocity.At the riser bottom, cluster frequency decreased with increasing solids circulating rate while cluster existence time increased with increasing solids circulating rates.
    Simulation of steady filtration process for parallel and staggered fibrous filter by lattice Boltzmann method
    WANG Haoming, ZHAO Haibo, ZHENG Chuguang
    2013, (5):  1621-1628.  doi:10.3969/j.issn.0438-1157.2013.05.017
    Abstract ( 1511 )   PDF (1618KB) ( 403 )  
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    Fibrous filter with the advantage of high capture efficiency of sub-micro particles is widely used in coal-fired power plants, mineral engineering, cement industry and other fields.The filtration process is very complex because of various capture mechanisms and the interactions among airflow, particles and fibers.Up to now, many researchers have investigated the filtration process of fibrous filter, especially the single fiber condition.A series of theories or equations have been presented to calculate pressure drop and filtration efficiency for the single fiber.By contrast, studies for multi-fiber condition are fewer than the single fiber condition.The existing studies of multi-fiber filtration process often focus on the factors(velocity of airflow, volume fraction, particle diameter, etc.)which may affect capture efficiency.It is worth noting that, the ultimate purpose for the study of filtration process should be optimization of fiber configuration for multi-fiber filter, and then a filter with high capture efficiency and low pressure drop can be obtained.However, there is no report about optimization for fiber configuration.In this paper, the lattice Boltzmann-cell automata(LB-CA)probability model was used to simulate the filtration process of multi-fiber filter.The pressure drop and capture efficiency with different mechanisms and fiber configurations were investigated, and the results obtained from the LB-CA model were in good agreement with existing results.The quality factor defined as ratio of capture efficiency and pressure drop was also introduced to weigh the fibrous filters.In order to present the optimization method for different particles, the capture ability of each fiber was first defined and calculated.Parallel model and staggered model for fiber configuration were presented.The quality factor of the staggered model was greater than that of the parallel model because of higher capture efficiency although its pressure drop was also larger.Through comparison of capture ability of fibers in different positions, it was found that the fore fibers were more efficient than the rear ones, especially in the inertial impaction capture mechanism.In the diffusional and interception mechanisms, the similar situation also existed but the contribution of rear fibers could not be neglected.The results showed that a filter with diminishing volume fraction along the depth direction might perform well in the filtration process with the diffusional and interception mechanisms; in the inertial impaction mechanism, the row number of fibers should not exceed two.
    Ru/γ-Fe2O3-Al2O3 catalyst for selective hydrogenation of benzene in magnetically stabilized bed
    FU Qingtao, LIU Chenguang, YU Lianqing
    2013, (5):  1629-1634.  doi:10.3969/j.issn.0438-1157.2013.05.018
    Abstract ( 1186 )   PDF (925KB) ( 286 )  
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    Ru-based magnetic(Ru/γ-Fe2O3-SiO2-γ-Al2O3)egg-shell catalysts were prepared by the impregnation method.A magnetically stabilized bed(MSB)unit was designed and used to characterize selective hydrogenation of benzene.The effects of catalyst preparation parameters and reaction conditions on selective hydrogenation of benzene were investigated.The results showed that the state of chain operation in MSB increased the selectivity for cyclohexene obviously, which verified that the magnetic ruthenium-based catalysts and magnetically stabilized bed had a good prospect of industrial applications.
    Preparation and characterization of sulfonated crosslinked chitosan resin as solid acidic catalyst
    LI Junhong, XU Yuting, TANG Chengli, LIU Xiong, TAN Yunfei, DONG Lichun
    2013, (5):  1635-1641.  doi:10.3969/j.issn.0438-1157.2013.05.019
    Abstract ( 2052 )   PDF (1080KB) ( 518 )  
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    Crosslinked chitosan resins(CCRs)with different crosslinking degrees were synthesized by using the inverse emulsion method and glutaraldehyde as crosslinking agent, and then sulfonated at -5℃ with concentrated H2SO4 as sulfonation agent.The properties and application of obtained sulfonated crosslinked chitosan resins(SCCRs)as solid acidic catalysts were studied.IR analysis showed that sulfonation of CCR occurred at both C2 amino groups and C6 secondary hydroxyl groups.Sulfur content measurements demonstrated that the higher the crosslinking degree of the SCCR, the larger the sulfonation rate of its C6 hydroxyl groups.The acidic sites in SCCR including C6-O and C2-N sulfate groups were all weak acidic sites.The acid content of SCCR was much higher than chitosan sulfate reported in the literature,which was prepared by direct sulfonation of chitosan without pre-crosslinking.High-temperature treatment verified that crosslinking improved the thermostability of SCCR.The SCCR with a higher crosslinking degree had better mass retention rate as well as larger sulfur retention rate.The catalytic activity and repeatability of SCCR as solid acidic catalysts were verified by testing its application in the synthesis of tributyl citrate from citric acid and butanol.The results showed that esterification rate of citrate acid could reach 94.8% when SCCR with a 100% crosslinking degree was used, and esterification rate could keep above 92% by repeated use of the SCCR for 6 times.Comparison with chitosan sulfate demonstrated that SCCR was a much better solid acidic catalyst and had a promising application prospect.
    Filtration mechanism of membranes in combination of catalytic wet air oxidation and membrane filtration
    LI Xiaoyi, WU Sijun, SUN Dezhi
    2013, (5):  1642-1650.  doi:10.3969/j.issn.0438-1157.2013.05.020
    Abstract ( 1544 )   PDF (2428KB) ( 380 )  
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    The treatment of simulated cationic red GTL dye wastewater was conducted by coupling technology of catalytic wet air oxidation(CWAO)with membrane filtration, using Mo-Zn-Al-O as catalyst.The filtration mechanism of polyvinylidene fluoride hollow fiber microfiltration(MF)membranes with average pore size 0.1 μm and ultrafiltration(UF)membranes with average pore size 0.022 μm was investigated.It was found that the degradation efficiency of hybrid system was superior to CWAO with single process.Under 0.01 MPa pressure for 120 min the fluxes of MF and UF declined 26.63% and 16.48%, respectively.The reason for flux decline of microfiltration membrane was considered to be the blocking of pores and the formation of cake layer on the membrane surface by deposited catalyst powder, while that of ultrafiltration was dominated by cake layer formation.The experimental results showed that the irreversible resistance in microfiltration was larger than that in ultrafiltration after the same process.Under different operation conditions, a linear relationship could be obtained between the filtration resistance and specific deposit.
    Thermodynamics and dynamics for adsorption of heavy metal ions on Pb(Ⅱ)ion-imprinted composite membrane
    FAN Rongyu, ZHENG Ximing
    2013, (5):  1651-1659.  doi:10.3969/j.issn.0438-1157.2013.05.021
    Abstract ( 1792 )   PDF (2302KB) ( 761 )  
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    A novel Pb(Ⅱ)ion-imprinted composite membrane with microporous polypropylene membrane(MPPM)as support was prepared by a modified UV-induced graft copolymerization.In the graft strategy, benzophenone was immobilized on membrane by combining physical entrapment and UV-induced covalent immobilization methods.The adsorption and selectivity capabilities of the imprinted composite membranes towards Pb(Ⅱ)were investigated with equilibrium adsorption and competitive permeation experiments.The imprinted composite membranes exhibit good adsorption and permselectivity towards Pb(Ⅱ).The maximum adsorption capacity towards Pb(Ⅱ)is 2.86 and 2.75 times that towards Cu(Ⅱ)and Zn(Ⅱ), respectively, and the permeation amount of Pb(Ⅱ)in 48 h is 3.8 and 3.1 times.Langmuir adsorption isotherm models fit the equilibrium experimental data well(R2≥0.991), indicating that the sorption is of monolayer-mode.The kinetics of the adsorption towards heavy metal ions follow the Lagergren pseudo- second-order model(R2≥0.998,ΔQ<10%), and the adsorption process is dominated by chemical interaction.The thermodynamic parameters of Gibbs free energy change(ΔG), enthalpy changes(ΔH), and entropy change(ΔS)are calculated.Negative values of ΔH suggest exothermic nature of the adsorption, and negative values of ΔG indicate spontaneous nature of process.|ΔH| > |TΔS| suggests that the adsorption of heavy metal ions on the imprinted composite membranes is driven by enthalpy.
    Extraction technology for recovery of gallic acid from gallic acid mother liquor
    YU Wei, ZHOU Kanggen, WU Yundong, DU Hu
    2013, (5):  1660-1664.  doi:10.3969/j.issn.0438-1157.2013.05.022
    Abstract ( 1256 )   PDF (893KB) ( 290 )  
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    A feasible extraction technology is investigated to recover gallic acid from gallic acid mother liquor.It is confirmed that methyl isobutyl ketone(MIBK)is a proper extractant.The influences of initial pH value, gallic acid concentration and phase ratio on extraction efficiency of MIBK are studied in detail.The results show that the pH value of extraction raffinate should be controlled to be less than 2.5 in the extraction process and at about 8 in the stripping process.The extraction rate is improved by increasing the phase ratio.The gallic acid concentration has no obvious effect on the extraction balance in both extraction and stripping processes.The multistage extraction rate reaches 95% at the phase ratio of 1 and the initial pH value of wastewater lower than 2.5.
    Recurrent neural network integrated with process-priori-knowledge and its application
    LOU Haichuan, SU Hongye, XIE Lei
    2013, (5):  1665-1673.  doi:10.3969/j.issn.0438-1157.2013.05.023
    Abstract ( 1170 )   PDF (2853KB) ( 350 )  
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    Most of chemical processes with nonlinear characteristics are difficult to model by general linear modeling approaches in practice.Hence, a novel recurrent neural network integrated with priori-knowledge for modeling nonlinear dynamic processes was presented.In the form of non-linear constraints, the priori-knowledge exploited from industrial chemical processes was embedded into the feed-forward neural network with the NARMAX(nonlinear autoregressive moving average with exogenous input)structure.Meanwhile, based on the augmented Lagrange multiplier(ALM)method, a hybrid PSO-IPOPT algorithm was introduced for network weight optimization.The PKRNN model with process-priori-knowledge constraint either ensured good dynamic modeling and prediction(especially extrapolation)ability, or guaranteed safety in the implementation of industrial chemical processes.The effectiveness of the PKRNN model was validated by an actual double-loop liquid propylene polymerization reaction process.
    Fault detection of complex chemical processes using Mahalanobis distance-based local outlier factor
    MA Hehe, HU Yi, SHI Hongbo
    2013, (5):  1674-1682.  doi:10.3969/j.issn.0438-1157.2013.05.024
    Abstract ( 1169 )   PDF (3625KB) ( 392 )  
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    Complex chemical processes often have multiple operating modes to meet the changes of production conditions.Meanwhile, process complexity makes the within-mode data usually follow an uncertain combination of Gaussian and non-Gaussian distributions.The multimode characteristics and the uncertainty of data distribution within one single mode make the conventional multivariate statistical process monitoring(MSPM)methods unsuitable for fault detection.In this paper, a novel Mahalanobis distance-based local outlier factor(MDLOF)method was proposed.The local structure of variables was taken into account by employing Mahalanobis distances, and the local density of the surrounding neighborhoods was also considered.A density-based monitoring statistics which was robust regardless of data distribution was obtained by this way.Finally, the validity and effectiveness of MDLOF were illustrated through a numerical example and the Tennessee Eastman process.
    Soft sensor of FCCU using nonlinear singular state observer
    XU Feng, WANG Yeye, LUO Xionglin
    2013, (5):  1683-1695.  doi:10.3969/j.issn.0438-1157.2013.05.025
    Abstract ( 1077 )   PDF (1923KB) ( 304 )  
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    Other than the conventional soft sensor of output correction, the primary variables of soft sensor in FCCU riser reactor are completely unmeasurable in real time, and they can only be corrected on-line by secondary variables, so the state observer was used to build soft sensor.FCCU is an index-one nonlinear singular system, so an index-one nonlinear singular state observer was designed for soft sensor to estimate the unmeasurable variables on-line, including product yields and catalyst circulation rate of FCCU.For index-one nonlinear singular system, if the linear parameter-varying singular system from local linearization at current operating point was detectable, a nonlinear singular state observer could run in a wide range, and its feedback gain matrix can be obtained on-line by pole assignment of the linearized system.The existence of nonlinear singular state observer can ensure that the estimated values of the primary variables will converge to their ideal values.Simulation showed that even if the catalyst circulation rate was unknown, when it was augmented as state variable and the temperature of FCCU riser outlet as secondary variable was used for output correction, a soft sensor based on nonlinear singular state observer could be established to estimate the unmeasurable variables, such as product yields and catalyst circulation rate on-line.The estimated values of the unmeasurable variables converged to the ideal values and the proposed observer had good dynamic performance.
    Total site gradual energy integration and optimization strategy based on T-H diagram
    WU Xianli, WU Lianying, HU Yangdong
    2013, (5):  1696-1703.  doi:10.3969/j.issn.0438-1157.2013.05.026
    Abstract ( 1171 )   PDF (1420KB) ( 384 )  
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    Based on the T-H diagram, the gradual optimization integration strategy for a large-scale complex process was proposed.By drawing the T-H diagram of the process, the bottlenecks and unreasonable heat transfer processes were analyzed.Through improving the process, introducing the turbine and heat pump of the system, the hot and cold streams were increased or changed, and the T-H diagram was changed accordingly.Repeating the above steps, two approximate parallel hot and cold stream curves were constructed.Energy was reasonably used, and the consumption of utilities was significantly reduced.In this strategy, energy utilization procedure and conversion procedure were comprehensively considered.By applying this strategy to a methanol to olefins plant, the energy integration of the plant was optimized.The results showed that this strategy was effective and convenient.
    Soft sensor of sodium aluminate solution concentration based on improved differential evolution algorithm and LSSVM
    QIAN Xiaoshan, YANG Chunhua, XU Lisha
    2013, (5):  1704-1709.  doi:10.3969/j.issn.0438-1157.2013.05.027
    Abstract ( 1190 )   PDF (1179KB) ( 389 )  
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    Aiming at online testing of concentration of sodium aluminate solution in evaporation process of alumina production, a modeling method for concentration of sodium aluminate solution based on improved differential evolution algorithm and least squares support vector machine was proposed.The input variables of the soft sensor model were determined by analyzing process parameters based on grey relational analysis and kernel principal components analysis,and then the LSSVM model was established based on improved differential evolution algorithm and compared with DE-LSSVM soft sensor model.Finally, the experimental results of industrial production data of evaporation process showed that the new model had better learning ability and generalization performance and higher prediction accuracy, and could provide necessary guidance for the evaporation process operation optimization.
    Multi-objective parametric optimization of power generation system based on organic Rankine cycle
    WANG Zhiqi, ZHOU Naijun, XIA Xiaoxia, WANG Xiaoyuan
    2013, (5):  1710-1716.  doi:10.3969/j.issn.0438-1157.2013.05.028
    Abstract ( 1558 )   PDF (1248KB) ( 540 )  
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    A multi-objective optimal model was developed, in which the screening criteria include heat recovery efficiency and heat exchanger area per unit power output.The model was optimized using the simulated annealing algorithm for R123, R236ea, R245fa, R227ea and R600.The results show that the multi-objective optimization model can coordinate the relationship of different criteria and is better for system economy than that of a single screen criterion.At heat source temperature of 140℃, the optimal evaporation and condensation pressures using R123 are 0.69 MPa and 0.11 MPa, respectively.The optimal evaporation pressure increases with the condensing pressure.The velocity in tubes should be more than 0.5 m·s-1 and the optimal pinch point in evaporator is about 15℃.As the waste heat temperature increases, the optimal evaporation pressure increases.In the waste heat temperature range from 100℃ to 220℃, R123 is the best working fluid among the five working fluids.
    Melt index prediction of polypropylene based on GMC(1,N)model
    WANG Mingxu, LIU Xinggao
    2013, (5):  1717-1722.  doi:10.3969/j.issn.0438-1157.2013.05.029
    Abstract ( 1145 )   PDF (652KB) ( 375 )  
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    Melt index(MI)is the most important parameter in determining polypropylene’s specifications and also the key of quality control.Considering the continuity of the polypropylene production process and the characteristics of gray prediction model, a new GMC(1,N)melt index prediction model is proposed in this paper to infer the MI of polypropylene from other process variables, which shows good applicability. Furthermore, a back propagation network is built to correct the residual of the model and the GMC(1,N)-BP model is improved with better precision.Standard SVM(support vector machines), LS-SVM and weighted LS-SVM model are taken for comparison.A practical polypropylene industrial process is taken as case study.The results show that the proposed improved model achieves good results in practical melt index prediction.
    Correction of contact fractal model for friction faces of mechanical seals
    WEI Long, GU Boqin, LIU Qihe, ZHANG Penggao, FANG Guifang
    2013, (5):  1723-1729.  doi:10.3969/j.issn.0438-1157.2013.05.030
    Abstract ( 1137 )   PDF (600KB) ( 480 )  
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    The existing problems of the original contact fractal model of friction pair faces of mechanical seals were analyzed, and the original model was modified.The relationship between bearing area ratio of asperity and face pressure on the friction pair faces was obtained.In the modified model, the effects of film pressure of fluid between the end faces of friction pair, the differences between real micro contact area and micro contact sectional area of asperity were taken into account.The relationship between elastic-plastic deforming asperity contact pressure and contact area was expressed by a cubic polynomial, which satisfied the continuous and smooth conditions of the transformation of asperity contact area and contact pressure at the critical point of transition of asperity distorting state.According to the modified model, the influence factors of asperity bearing area ratio of friction pair faces matched by cemented carbide YG8-carbon graphite M106K of partial balance mechanical seals were analyzed.The results showed that the asperity bearing area ratio increased approximately linearly with spring pressure, increased monotonously nonlinearly with fluid pressure, increased at first and then decreased with the increase of fractal dimension, and decreased with the increase of characteristic length scale.The real contact area accounts for only a small part of the nominal contact area under normal operating conditions.
    Preparation and characterization of carbon supported CoNi alloy nanoparticles electrode and their electrocatalytic properties
    OU Jielian, CHEN Yanxin, LI Mingxuan, XU Binbin, WANG Peng, CHEN Shengpei, SUN Shigang
    2013, (5):  1730-1735.  doi:10.3969/j.issn.0438-1157.2013.05.031
    Abstract ( 1295 )   PDF (676KB) ( 308 )  
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    CoNi alloy nanoparticles were synthesized on glassy carbon(GC)electrode(CoNi/GC)by electrochemical deposition.SEM images showed that the prepared CoNi alloy nanoparticles were 18-facet polyhedra with an average particles size of 100 nm, dispersed on the GC electrode surfaces uniformly.The selected area electron diffraction(SAED)pattern showed that CoNi alloy nanoparticles were single crystals.X-ray photoelectron spectroscopy(XPS)showed that the Co(0)and Ni(0)were dominant.The electrocatalytical activities for nitrite reduction of bulk Co, bulk Ni and CoNi/GC electrodes were investigated by cyclic voltammetry(CV).Onset potential(Ei)of nitrite reduction on CoNi/GC electrode was positively shifted 90 mV, and peak current density(jp)was 6-14 times higher than those of bulk Co and bulk Ni electrode.CoNi/GC electrode also showed an enhancement of electrocatalytical activity towards oxygen reduction reaction, of which peak current density(jp)was 1.7 times and dynamic current density(jk)was 5.2 times higher than those of GC electrode.
    Influence of electrostatic water treatment on crystallization behavior of CaCO3 and synergistic scale inhibition with a green scale inhibitor
    LI Haihua, LIU Zhenfa, GAO Yuhua, ZHANG Lihui, LI Xiaohui
    2013, (5):  1736-1742.  doi:10.3969/j.issn.0438-1157.2013.05.032
    Abstract ( 911 )   PDF (1124KB) ( 274 )  
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    The influences of electrostatic water treatment on crystallization behavior and crystal forms of CaCO3 were investigated by using non-evaporation method.A stable stage existed in the early stage of the CaCO3 crystallization in the water sample treated by electrostatic field, and the length of the stage was affected remarkably by temperature.For instance, the stage lasted 3 h at 60℃, but less than 0.5 h at 80℃.The results of SEM and IR show that the content of aragonite increases in the scale sample formed in the electrostatic water.The appearance of the stable stage and aragonite is because H2O molecules and HCO3- are polarized by electrostatic field and their reactivity increases.The results of the static and dynamic scale inhibition experiments prove obvious synergistic scale inhibition effect between the electrostatic water treatment and polyepoxysuccinic acid(PESA).With PESA in the electrostatic water, the static scale inhibition rate reaches 95.8%, which is 18.9% higher than that in the prepared water, and the dynamic scale inhibition rate is 92.1%, which is 14.5% higher than that in the groundwater.
    Streaming potential and wall slip effects on pressure-driven microchannel flow
    LIU Ying, TAN Dekun
    2013, (5):  1743-1749.  doi:10.3969/j.issn.0438-1157.2013.05.033
    Abstract ( 760 )   PDF (1109KB) ( 303 )  
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    This study investigated the streaming potential and wall slip effects on pressure-driven liquid flow in hydrophobic microchannels.The Poisson-Boltzmann equation for the electrical double layer(EDL)and Navier-Stokes equation for incompressible viscous fluid were established.For those microchannels with high wall zeta potential, the traditional Debye-H點kel linear approximation for solving the potential distributions of EDL would produce big error, therefore, analytical expression for potential distributions and Navier slip boundary condition were introduced to solve the N-S equation analytically, then analytical solution of streaming potential could be obtained by using the electrical current balancing condition.The influences of electrokinetic parameter(K), wall zeta potential and slip coefficient on streaming potential and velocity distributions were discussed in detail.The results showed that streaming potential decreased with increasing electrokinetic parameter, while increased significantly with increasing slip coefficient.It also tended to reach a maximum value at a certain zeta potential and then decreased rapidly with increasing zeta potential.Streaming potential and wall slip both affected fluid flow in microchannels, the former retained the development of liquid flow, but the latter accelerated flow velocity.Wall slip effect played a major role at lower zeta potentials, that is, flow velocity increased at lower zeta potentials when the combined effects of streaming potential and hydrodynamic slippage appeared in microchannels.Wall slip velocity gradually reduced to zero at higher zeta potential, then wall slip effect on pressure-driven flow in microchannels could be ignored.
    Preparation and separation of Fab and Fc fragments from human immunoglobulin G with papain digestion
    TANG Siyuan, LIN Dongqiang, TONG Hongfei, YAO Shanjing
    2013, (5):  1750-1756.  doi:10.3969/j.issn.0438-1157.2013.05.034
    Abstract ( 1900 )   PDF (1141KB) ( 692 )  
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    For the preparation of Fab and Fc fragments with high purity,human immunoglobulin G (hIgG) was treated with papain and its purification with chromatographic techniques was explored.The concentration of cystein,papain addition,pH and incubation time were optimized to improve digestion efficiency with papain,and conversion of IgG could reach more than 98%.Then Protein A affinity chromatography and DEAE anion-exchange chromatography were used to separate the Fab and Fc fragments from the digestion mixture of hIgG.Based on the SEC-HPLC analysis,the purity of Fab fragment was 96.6% with the yield of 40.1%,while the purity of Fc fragment was 95.7% with the yield of 72.6%.
    Mechanism analysis of lignin slow pyrolysis
    CHENG Hui, YU Jian, YAO Meiqin, XU Guangwen
    2013, (5):  1757-1765.  doi:10.3969/j.issn.0438-1157.2013.05.035
    Abstract ( 1672 )   PDF (890KB) ( 489 )  
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    The characteristics of lignin pyrolysis was investigated by TG at different heating rate, combined with FTIR characterization of the chars from different stages of slow pyrolysis of lignin to analyze lignin pyrolysis mechanism at slow heating rate.The results show that pyrolysis of lignin is a process involving breakage of old chemical branched chains and recombination of new branched chains.With time extending i.e.temperature rising, there are three successive stages in process of lignin pyrolysis:dewatering, breakage-recombination-volatilization of branched chains and polymerization of aromatic rings and formation of carbon.Based on the weight loss rate at different heating rates, according to the Flynn-Wall-Ozawa equation, the calculation of kinetic parameters resulted in activation energies of 64 kJ穖ol-1 and 132 kJ穖ol-1 for the latter two pyrolysis stages, respectively.This indicates further that the pyrolysis of lignin carried out in different stages and the breakage of the branded chains was easier than the polymerization of aromatic rings.
    A novel model for process of pentosan digestion during steam treatment of green bamboo
    LUO Xiaolin, HU Huichao, MA Xiaojuan, CAO Shilin, LI Canghai, HUANG Liulian, CHEN Lihui
    2013, (5):  1766-1772.  doi:10.3969/j.issn.0438-1157.2013.05.036
    Abstract ( 1358 )   PDF (588KB) ( 294 )  
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    Green bamboo was hydrolyzed in a range of certain condition by steam treatment.Based on the parameters obtained in theoretical kinetic model, a novel model was developed for prediction of pentosan leaching out during steam treatment of green bamboo.Firstly, it should be pointed out that the traditional model based on derivation of severity factor was not successful for prediction of the pentosan leaching out. So, the development of a novel model is necessary.Based on the experimental data of pentosan digestion at isothermal pseudo-homogeneous process, the activation energy and frequency factor for irreversible first order kinetics was calculated as 48.1 kJ穖ol-1 and 4330 min-1 respectively.After introducing "potential hydrolysis degree(hd)" into the novel prediction model, numerical algorithm was used for calculation of severity factor in non-isothermal process.The model containing the severity factor was effective for prediction of pentosan leaching out during whole treatment process of green bamboo by steam.The agreement between model predicted and experimental data is good, and the correlation coefficient is 97%.This model could be used for control of pentosan digestion from green bamboo with steam treatment and for clarifying the effect of pretreatment on subsequent enzymatic hydrolysis.
    Preparation and application of PEDOT/MWCNTs composite anode for MFC
    LIU Xingqian, WANG Xuyun, GUO Qingjie
    2013, (5):  1773-1779.  doi:10.3969/j.issn.0438-1157.2013.05.037
    Abstract ( 1631 )   PDF (1535KB) ( 353 )  
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    A poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotubes(PEDOT/MWCNTs)composite anode was prepared and used for modification of graphite rod via cyclic voltammetry, and applied in anaerobic fluidized bed microbial fuel cell(AFBMFC)to investigate its electricity generation performance.Field emission scanning electron microscopy(FESEM)was employed to characterize the surface morphology and cross-section structure of PEDOT/MWCNTs composite anode.The electrochemical behavior of the modified anodes with or without MWCNTs was studied by means of cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).The results showed that the performance of the composite anode was superior and its maximum output power density up to 217 mW穖-2, which was 30% higher than that of modified anode by PEDOT; The open circuit voltage was up to 837.8 mV.The COD removal rate reached 96.4% after MFC run 3 days.The results illustrated that the composite anode possessed good electricity generation performance and sewage treatment efficiency in the AFBMFC under the condition of mass transfer reinforcement depending on liquid-solid fluidized bed.In addition, the adding of carbon nanotubes improved the conductivity of composite anode and the state of microbial adhesion.
    Effect of anode and cathode flow fields on performance of direct methanol fuel cell
    CAO Xianqi, HAN Jitian, CHEN Peipei, YU Zeting
    2013, (5):  1780-1788.  doi:10.3969/j.issn.0438-1157.2013.05.038
    Abstract ( 1536 )   PDF (2585KB) ( 354 )  
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    The effect of anode and cathode flow fields on the performance of a direct methanol fuel cell(DMFC)was experimentally investigated.Serpentine flow field(SFF), parallel flow field(PFF)and interdigitated flow field(IFF)were designed, fabricated and tested.The studies were conducted in a DMFC with an active membrane area of 25 cm2, working at ambient temperature, using two kinds of methanol concentration solution(1 mol稬-1 and 2 mol稬-1), of methanol flow rates(2.1 ml穖in-1and 7 ml穖in-1)and of oxygen flow rates(100 ml穖in-1and 300 ml穖in-1).The results show that SFF as anode flow field has a positive effect on cell voltage and power as better removal of CO2 bubbles.It is also found that CO2 bubbles block flow channels in both PFF and IFF at high current densities, which leads to worse cell performance.For cathode flow field, it is found that water drops block flow channels in PFF, but this channel-blocking phenomenon is never found in both SFF and IFF.The DMFC equipped with both SFF and IFF yields much better performance than that with PFF.The IFF can enhance oxygen transport and cells gain better performance than that with SFF at high current densities.So, it could be deduced that SFF as anode flow field and IFF as cathode flow field would be one of the best choice for the DMFC.
    Simulation and optimization of SNCR process
    LI Qiong, WU Yuxin, YANG Hairui, LÜ Junfu
    2013, (5):  1789-1796.  doi:10.3969/j.issn.0438-1157.2013.05.039
    Abstract ( 1837 )   PDF (1039KB) ( 469 )  
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    Using computational fluid dynamics(CFD)method,the urea-based selective non-catalytic reduction(SNCR)process in a 100 t·h-1 circulating fluidized bed(CFB)boiler was numerically simulated to study effect of temperature and normalized stoichiometric ratio(NSR)on SNCR denitration efficiency, NH3 slip and N2O formation.The results show that the window of optimized temperature for SNCR process is in a range of 850-1050℃ and becomes wider with increasing NSR; when temperature rises, NH3 slip decreases obviously and can be ignored if temperature is higher than 940℃.With increase of temperature, amount of N2O formation increases first and then decreases.With increasing NSR, the denitration efficiency and NH3 slip increase.The denitration efficiency is the maximum at 980℃.Formation of N2O is in proportion to denitration efficiency and the maximum about 30 μl·L-1.
    Separation mechanism and application of oil-water microemulsion
    QIN Juan, XIN Yinchang, MA Dehua
    2013, (5):  1797-1802.  doi:10.3969/j.issn.0438-1157.2013.05.040
    Abstract ( 1563 )   PDF (740KB) ( 446 )  
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    A special surfactant can make thermodynamically stable microemulsion liquid change to thermodynamically unstable state, and its complex with a polymer can do the microemulsion separation into a mixture of oil and water.It is found by transmission electron microscopy(TEM)analysis that size of particles dispersed in transparent deinking paper wastewater containing insoluble organic matter is much smaller than visible light wave-length, and this wastewater is at microemulsion state.So, the transparent deinking paper wastewater was taken as test sample, and treated with this complex(a mixture of special surfactant cBPE-2030 and polymer LYPW-301).The chemical oxygen demand(COD)was determined. The results showed that COD value after treatment with this complex was significantly reduced.The mechanism of oil and water separation was explored by TEM analysis for microscopic state change of microemulsion and emulsion liquids.The method separating oil and water of microemulsion could be effectively applied to other transparent wastewater from papermaking and oilfield, whose separation, in general, is difficult.
    Adsorption of phosphate on magnetite-goethite mix phase
    SHAO Penghui, TANG Chaochun, JIAN Meipeng
    2013, (5):  1803-1809.  doi:10.3969/j.issn.0438-1157.2013.05.041
    Abstract ( 2184 )   PDF (476KB) ( 427 )  
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    An adsorbent was first prepared from used hot pack, and adsorption of phosphate on it studied. The interaction between pH, adsorption performance and zeta potential was also investigated and the adsorption mechanism at different pH values did.The results showed that the adsorbent were mainly composed of mix phases of magnetite and goethite.The isotherm of phosphate adsorption could be well described by Langmuir equation.The capacity of its equilibrium adsorption was 12.57 mg·g-1 at temperature 25℃ and pH 2.The studies also indicated that adsorption of phosphate on the adsorbent was dominated by solution pH.Inner-sphere complexing, electrostatic attraction and direct precipitation on surface were jointly driving force for adsorption of phosphorus at lower pH.At higher pH, inner-sphere complexing decreased and electrostatic attraction became electrostatic exclusion, which was unfavorable for phosphate adsorption, however, co-adsorption with inner-sphere complexing and indirect precipitation on surface promoted adsorption of phosphate, and total effect is decline of phosphorous removal.
    Dewatering performance of sludge modified by desulfurization ash
    XING Yi, HONG Chen, ZHAO Fan
    2013, (5):  1810-1818.  doi:10.3969/j.issn.0438-1157.2013.05.042
    Abstract ( 1506 )   PDF (1732KB) ( 313 )  
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    Sewage sludge modified by desulfurization ash and PAM was dewatered and its mechanism studied.The results show that dewatering performance for sludge can be greatly improved by adding desulfurization ash.When desulfurization ash of 3 g稬-1 is mixed with sludge, the biggest volume of sludge sedimentation is 519.5 ml and the decrease of specific resistance(SRF)47.56%, indicating that desulfurization ash makes EPS breaking away and releasing bound water.Better dewatering performance can be obtained by treating sewage sludge with both desulfurization ash with polyacrylamide(PAM).By comparing particle size distribution and scanning electron micrographs(SEM)for original and modified sludge, it is found that the particle size of sludge flocs is obviously smaller for modified sludge than for original one, the frame structure of its small pore has been changed and solider and denser flocs with larger aperture do formed, which makes moisture in sludge removing more easily.PAM plays a role in bridging of particles by adsorption bridge effect and bigger flocs are formed rapidly from unstable sludge flocs, which is more easily for solid-liquid separation to improve sludge dewatering performance.
    Strengthen of coagulation for light pollution water with low turbidity by recycling of backwash water from filter
    XIE Si, YANG Yanling, LI Xing, ZHOU Zhiwei, SU Zhaoyang, LI Bo, LIU Ling
    2013, (5):  1819-1824.  doi:10.3969/j.issn.0438-1157.2013.05.043
    Abstract ( 1197 )   PDF (415KB) ( 338 )  
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    This study focuses on distribution of light pollution water with low turbidity, by adjusting dosage of polyaluminum chloride(PACI)to control floc zeta potential.Influence of backwash water(FBWW)with different coagulation characteristics from filter on coagulation efficiency was also investigated.The results show that FBWW is of good efficiency on turbidity removal as zeta potential close to -11 mV.The maximum removal rate for settled water was 63.81%, and it was higher than that at other potentials by using this processing.And the lowest residual AlP content was found about 0.271 mg稬-1 at this potential.However, excessive backflow(12%)can lead to additional consumption of PACl in this stage, which makes particle matter in raw water to obtain sufficient coagulant difficult and the system to lose stabilization, and so, turbidity, CODMn, AlP, AlD, etc.goes up.When zeta potential is close to 0 mV, the FBWW is also of good effect on CODMn, UV254 and AlP,and AlD can stay in a relative low value as well. If reflux ratio is 9%, the removal rate of CODMn can reach the highest test value, about 34.21%.When zeta potential is placed at close to +4 mV, the reflux of FBWW can cause substantial increase of turbidity, CODMn, AlP and AlD, while removal efficiency for UV245 is improved.This trend was most obvious for the backflow ratio about 12%, at which the highest test value of UV254(60.67%)is obtained.By comparing residual organic matters in filtered and settled water, a significant difference between these organic matters is found.The removal rates of UV254 and CODMn were higher for the filtered water at +4 mV.
    Fluorescence characteristics of dissolved organic matter in coagulation process of recycling filter backwash water
    ZHOU Zhiwei, YANG Yanling, LI Xing, LIU Yongwang, SU Zhaoyang
    2013, (5):  1825-1832.  doi:10.3969/j.issn.0438-1157.2013.05.044
    Abstract ( 1181 )   PDF (3690KB) ( 343 )  
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    The impacts of recycling filter backwash water(FBWW)blended with corresponding raw water W1(simulated water)and W2('Longtan’ lake water)on specific bulk water parameters, i.e.DOC, UV254 and specific ultraviolet absorbance(SUVA)removal were evaluated in coagulation-sedimentation processes.Fluorescence characteristics of dissolved organic matter(DOM)in source waters, FBWWs and treated water were identified and compared.As compared with control trial without FBWW, three volumetric recycling ratios at 2%, 5% and 8% were investigated.The results indicated that fluorescent components in raw water and corresponding untreated FBWWs DOM were mainly humic-like fluorophore(Peak A)and protein-like fluorophore(Peak T), with Ex/Em wavelengths at 245.0-265.0 nm/400.0-435.0 nm, 280.0-305.0 nm/305.0-345.0 nm, respectively.Additionally, a broad Peak C with relatively lower fluorescence intensity was observed in all fluorescence spectra.At observed recycling rates, organic matter removal rates in treated water were improved with FBWW1, while the enhanced removal efficiencies of DOM in treated samples with FBWW2 were unconspicuous.Fluorescence EEM spectra in the DOM of treated water samples were analogous to those of source water accordingly.The process of recycling FBWW could improve humic-like substances(Peak A)removal, but the protein-like matters were resistant to elimination or even enriched with unvaried structure.The DOM removal in the coagulation process of recycling filter backwash water could be well identified by the three-dimensional excitation emission matrix(3D-EEM)fluorescence technique, therefore it could be used in wide applications.
    Stabilization technology in treating municipal solid waste incineration fly ash using heavy metal chelating agent
    XU Ying, CHEN Yu, FENG Yueyang
    2013, (5):  1833-1839.  doi:10.3969/j.issn.0438-1157.2013.05.045
    Abstract ( 2341 )   PDF (1355KB) ( 625 )  
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    In view of treatment efficiency and stability about stabilization treatment of fly ash from municipal solid waste incineration,a stabilization technology was developed for treating heavy metals in fly ash using organic heavy metal chelator ammonium dipropyl dithiophosphate(ADD).The effect of pH on heavy metal leached amount from stabilized fly ash was studied.The contents of different forms of heavy metals in fly ash were compared before and after stabilization treatment with ADD chelator,and the stabilization effect was analyzed with different amounts of ADD chelator.The result showed that stabilization rate against Pb,Zn,and Cd of 1.5% ADD chelator reached 95.6%,85.5% and 93.4% respectively,and the amounts of Pb,Zn,and Cd in the leachate met the Pollution Control Standards for Hazardous Waste Landfill(GB 18598-2001)at pH values exceeding 3.The contents of Pb,Zn and Cd bound to carbonates in fly ash after ADD chelator treatment was significantly decreased with significantly increased contents bound to organic matter.The Pb,Zn and Cd stable form contents increased by 15.4%,17.1% and 24.3% respectively,and accordingly reduced the risk of secondary pollution of stabilized products under environment change.The stabilization effect of ADD chelator on heavy metals in fly ash was apparently better than that of inorganic stabilizing agent lime and sodium sulfide.
    Factors affecting phosphorous removal and reaction kinetics for Fe(Ⅱ)/O2 system
    LI Ting, DONG Wenyi, WANG Hongjie, LIN Jinnan, ZHANG Qian, OUYANG Feng
    2013, (5):  1840-1846.  doi:10.3969/j.issn.0438-1157.2013.05.046
    Abstract ( 1480 )   PDF (950KB) ( 322 )  
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    Considering low cost and high efficiency of ferrous iron for phosphorous removal, ferrous iron was used for removing phosphorous in wastewater by oxidation.The efficiency, affecting factors and kinetics of the oxidation process of ferrous iron were studied in this paper.The results show that simultaneous oxidation of ferrous iron can improve significantly the efficiency of phosphorous removal by ferrous iron.When DO raise from 0 to 4 mg稬-1, the rate of phosphorous removal increases by 47% after 60 min.The rate increases first and then decreases with pH from 6.0 to 9.0.The optimal pH is 8.0.Both raise of temperature and initial concentration of ferrous iron can enhance phosphate removal.A series of basic data are provided for wide use of ferrous iron.
    Synthesis of ultrafine copper chromite black pigment by chemical coprecipitation using SBDS-assisted urea
    WANG Weiwen, ZHENG Xiaodan, LI Ping, XU Hongbin, ZHANG Yi
    2013, (5):  1847-1854.  doi:10.3969/j.issn.0438-1157.2013.05.047
    Abstract ( 1476 )   PDF (2123KB) ( 470 )  
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    The ultrafine copper chromite black pigment(CuCr2O4)with spinel structure was prepared from chromium and copper nitrates by the chemical coprecipitation method, using sodium dodecyl benzene sulfonate(SDBS)as surface active agent and urea as precipitation agent.The effect of processing parameters, such as precipitation agent, calcination temperature and surface active agent on crystal structure, grain size and morphology of the CuCr2O4 was investigated, and the effect of processing parameters on its tinting strength was discussed.The results showed that urea and SDBS could effectively control grain size, morphology and crystal structure of the pigment.Ultrafine CuCr2O4 300 nm in size and with hexagonal structure was synthesized under the conditions of 400% theoretical amount of urea, 5% SDBS and 800℃ of calcination temperature, and exhibited excellent tinting strength compared with commercial samples.
    Lipase-catalyzed synthesis and characterization of high-molecular-weight PBS
    AN Siyuan, ZHU Jingying, LU Diannan, LIU Zheng
    2013, (5):  1855-1861.  doi:10.3969/j.issn.0438-1157.2013.05.048
    Abstract ( 1346 )   PDF (929KB) ( 319 )  
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    In the present study, high-molecular-weight PBS was synthesized by using immobilized Candida antarctica lipase B(Novozym-435)as catalyst and diethyl succinate and 1,4-butanediol as reagents.The PBS with molecular weight of 44000 was synthesized after 25 h polymerization at 95℃ and 10 mmHg vacuum, which was the highest molecular weight of PBS synthesized by the enzymatic method reported so far.The structure of polyester was determined by IR, NMR and elemental analysis.Enzymatic kinetics of PBS synthesis was monitored and the stability of lipase was investigated.In addition, thermal stability and biodegradable ability of blended polymer materials of enzyme-catalyzed polyester and chemical-catalyzed polyester were also investigated, displaying wonderful performance of synthesized PBS in the field of food and medical application.
    Molecular dynamics simulation of interactions on graphene/polyaniline nanocomposites interface
    JIA Haipeng, SU Xunjia, HOU Genliang, CAO Xiaoping, BI Song, LIU Zhaohui
    2013, (5):  1862-1868.  doi:10.3969/j.issn.0438-1157.2013.05.049
    Abstract ( 2219 )   PDF (1240KB) ( 614 )  
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    Graphene receives world-wide attention due to its unique two-dimensional structure and exceptional electrical and mechanical properties.Graphene/polyaniline(Gr/PANI)nanocomposites, were synthesized via dispersing the graphene into polymers, and could be used in microwave absorption, supercapacitors and electronic devices.Molecular dynamics simulations were carried out to investigate the microscopic mechanism of interactions on Gr/PANI nanocomposites interface.The interaction configurations, intermolecular interaction energy and pair correlation functions between graphene and PANI were computed.The curves of temperature, energy evolution and interaction energy analysis indicated that Gr/PANI system reached equilibrium in a relatively short period of time and it was a thermodynamic equilibrium system.The interaction configurations showed that there was an attractive interaction between graphene and PANI.Pair correlation functions revealed strong interactions between graphene and PANI, which were strong short-range nonbonded interactions.The strong interactions mainly arised from the sp2 hybridized π-conjugated structure of graphene and PANI.
    Producing PMMA fibers by electrospinning and model prediction
    LI Lu, LI Ruosong, LIU Lingna, FANG Tao
    2013, (5):  1869-1875.  doi:10.3969/j.issn.0438-1157.2013.05.050
    Abstract ( 1687 )   PDF (3551KB) ( 638 )  
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    PMMA fibers were produced by electrospinning from PMMA(poly-methyl-methacrylate)/ethyl acetate solution.Scanning electron microscope(SEM)was used to observe the fibers morphology. The influence of solution concentration, solution flow rate and operating voltage on fiber average diameter was investigated.The Box-Behnken design was used with three main factors, i.e.PMMA solution concentration, solution flow rate and operating voltage.Average diameter of PMMA nanofiber was set as response value.A binary regression model with a high degree of matching the results of experiment was set up by regression analysis.In addition, the results of response surface analysis agreed with univariate analysis results.
    Dispersion of pigment particles in polyacrylate latex film containing phthalocyanine blue
    QI Dongming, XU Jie, CHEN Zhijie, YANG Lei, WU Minghua, GUO Wendeng
    2013, (5):  1876-1883.  doi:10.3969/j.issn.0438-1157.2013.05.051
    Abstract ( 1405 )   PDF (4080KB) ( 471 )  
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    Pigmented latex films were formed from organic pigment phthalocyanine blue and ultrasonic blended latex containing butyl acrylate-styrene copolymer latex(abbreviated as PA+PB)and composite latex prepared via mini-emulsion polymerization(abbreviated as PA/PB)at room temperature respectively and then the films were cured at 120℃.Morphology of pigmented latexes, pigment dispersion in the interior and on the surface of latex films, and color of pigmented latexes were analyzed by DLS, FE-SEM,(Section)-TEM and spectrophotometry.The film formation mechanisms of two kinds of pigmented latexes were studied and compared.It was found that, the binding capacity between pigment and adhesive in blended latex PA+PB were poor.Migration and aggregation of pigment particles would generally occur during film formation, and thus many loose pigment aggregations at micron size could be formed on the surface and in the interior of pigmented latex.In composite latex PA/PB, pigment particles were pre-encapsulated in the interior of quasi-nanoscale adhesive particles.This microcapsule structure led to less obvious effect of pigment particles on film formation.Thus the size of pigment aggregate could be controlled on quasi-nanoscale, and almost all pigment particles could be dispersed in the whole film at the primary particle level.This would give the composite latex PA/PB film better color depth, color fastness and color uniformity.
    Solvent free synthesis of methyl dihydroxyethyl allyl ammonium chloride
    MAO Taoyan, ZHENG Cheng, LIN Jing, CHEN Xiaoling, HUANG Xiaoluo, XING Xu, ZHANG Liping
    2013, (5):  1884-1889.  doi:10.3969/j.issn.0438-1157.2013.05.052
    Abstract ( 1397 )   PDF (828KB) ( 345 )  
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    Methyl dihydroxyethyl allyl ammonium chloride(MDAAC)was synthesized from N-methyl diethanolamine( MDEA )and allyl chloride by the solvent-free synthesis method.The effects of reaction time, reaction temperature and reactant molar ratio on reaction conversion rate were studied.The optimum process of synthesizing MDAAC obtained by orthogonal experiment was 60 min reaction time, 50℃ reaction temperature and 1∶1.3 molar ratio of MDEA and allyl chloride.The target product was purified by recrystallization and the yield of product was 97%.The structure of product was characterized by IR,1H NMR and 13C NMR.