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Table of Content
05 June 2016, Volume 67 Issue 6
    CIESC Journal (HUAGONG XUEBAO) Vol.67 No.6 June 2016
    2016, 67(6):  0-0. 
    Abstract ( 34 )   PDF (1554KB) ( 138 )  
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    Development of pressure retarded osmosis membrane
    WANG Xiuheng, LU Jiandong, ZOU Yachao, YOU Shijie, TANG Chuyang
    2016, 67(6):  2187-2194.  doi:10.11949/j.issn.0438-1157.20151738
    Abstract ( 186 )   PDF (516KB) ( 1127 )  
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    Pressure retarded osmosis (PRO) is a new membrane technology to produce renewable energy from osmotic pressure difference of two solutions with different concentration. Membrane used in the PRO process requires high water permeability, effective rejection of salt and ideal mechanical strength in order to achieve an excellent energy production. This paper explains the basic requirements of PRO membranes and summaries the development of the widely-used asymmetric membranes from the aspects of active layer, support layer and pre-treatment, showing the effects of membrane material, preparation and pre-treatment on the membrane performance. Meanwhile, the paper induces the research status of symmetric and quasi-symmetric membranes, which could significantly mitigate internal concentration polarization (ICP) and become a research focus in the future.

    New direction of life cycle assessment: GIS-based life cycle assessment
    TIAN Yajun, DENG Yelin, ZHANG Yueling, XIE Kechang
    2016, 67(6):  2195-2201.  doi:10.11949/j.issn.0438-1157.20151795
    Abstract ( 240 )   PDF (615KB) ( 622 )  
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    The study presents an overview on the development of regionalization of life cycle assessment (LCA). The results of the paper indicate that incorporating spatial information into the process of the life cycle assessment is both necessary and feasible. The GIS (geographical information system), on the other hand, is an important platform to serve the purpose. The paper shows that GIS can effectively align and manage the spatial data in a flexible way, and thus promote the application of regionalized LCA study. The paper proposes a framework for the design of GIS based LCA. By integration GIS and LCA, the accuracy and representativeness of LCA results can be upgraded, which lays a solid foundation for policy making process.

    Thermodynamic analysis of mass and heat recovery adsorption refrigeration cycles and scheme selection
    XU Shengzhi, WANG Liwei, WANG Ruzhu
    2016, 67(6):  2202-2210.  doi:10.11949/j.issn.0438-1157.20151803
    Abstract ( 239 )   PDF (1349KB) ( 271 )  
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    Adsorption refrigeration is an energy-saving and environmental-friendly refrigerating method, which can utilize low-grade thermal energy. Under air-conditioning working conditions, silica gel-water mass and heat recovery systems are most often used. In order to understand which kind of cycle can improve the performance of the system under specific working conditions, the evaluating indicators of the first and the second laws of thermodynamics were adopted to analyze the COP, the exergetic efficiency and the cycle entropy production of the basic cycle, mass recovery cycle and mass and heat recovery cycle. The analysis showed that only when the heating source temperature was relatively low, the COP of mass recovery cycle was remarkably higher than that of basic cycle. The COP of mass and heat recovery cycle was significantly higher than that of mass recovery cycle only when the heating source temperature was relatively high. Consequently, the mass recovery cycle had its recommended highest heating source temperature and optimum heating source temperature, while the mass and heat recovery cycle had its recommended lowest heating source temperature and optimum heating source temperature. For example, under the typical air-conditioning working condition in summer of 90℃ heating source temperature, 10℃ evaporating temperature and 40℃ condensing temperature, the recommended highest heating source temperature of mass recovery cycle was 93℃, which is higher than the heating source temperature of 90℃. As a result, the mass recovery cycle was more suitable under this working condition and should be chosen rather than the mass and heat recovery cycle. Finally, the analysis of a chiller indicated that the given method and recommended working temperature intervals could provide guidance or advice on the scheme selection and system control for real systems.

    Characteristic analyses of boiling phenomena in process of drops impingement on heated surfaces
    LIANG Gangtao, MU Xingsen, GUO Yali, SHEN Shengqiang, ZHANG Jili
    2016, 67(6):  2211-2217.  doi:10.11949/j.issn.0438-1157.20151549
    Abstract ( 188 )   PDF (1339KB) ( 425 )  
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    An experimental process of liquid drops impingement on heated surfaces was observed using a high-speed digital camera, for which characteristics of boiling phenomena with different fluids were analyzed, and formation mechanisms of the central jet and pagoda-like bubbles were also discussed. At the surface temperature above the Leidenfrost point when the water drops impingement on the surfaces, a phenomenon of explosive boiling occurred, while that of the central jet happened for the drops of sodium chloride solution due to bubble entrainment with dramatic nucleation, and that of alcohol drops rebound entirely appeared. Otherwise, at the surface temperature below the Leidenfrost point, bubbly boiling was observed, for which different from hemispherical bubbles, pagoda-like bubbles appeared at the thicker film region. Moreover, the maximum spreading factor during drop rebound on heated surfaces was investigated quantitatively, which only can be influenced by the Weber number. Compared with the literatures, the empirical correlation of the spreading factor in this study can well predict the drop spreading scale on heated surfaces.

    Analysis of influence of pore density on heat transfer and pressure drop characteristics of wet air in metal foams
    WENG Xiaomin, HU Haitao, LAI Zhancheng, ZHUANG Dawei, DING Guoliang
    2016, 67(6):  2218-2223.  doi:10.11949/j.issn.0438-1157.20151712
    Abstract ( 135 )   PDF (1630KB) ( 260 )  
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    The heat transfer and pressure drop characteristics of wet air in metal foams with different pore density were experimentally investigated, and the comprehensive performance of metal foam heat exchangers was analyzed. The test sample is copper foam, the PPI value of the tested metal foam covers 5-40 and the porosity is 95%. The results showed that the heat transfer coefficient increased initially and then decreased with the increase of PPI values due to the presence of the condense water. It reached up to the maximum value as the pore density was 15 PPI. The pressure drop increased with increasing pore density and the increment was more obvious as PPI value was higher than 20. The comprehensive performance was the best for the metal foam with 15 PPI by considering both the heat transfer coefficient and pressure drop.

    Visualization and prediction model on shape of liquid bridge
    ZHUANG Dawei, YANG Yifei, HU Haitao, DING Guoliang
    2016, 67(6):  2224-2229.  doi:10.11949/j.issn.0438-1157.20151707
    Abstract ( 82 )   PDF (1297KB) ( 226 )  
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    Water bridge can affect the performance of fin-and-tube heat exchanger working under dehumidifying. In order to know the influence of water bridge on heat exchanger, the shape of water bridge needs to be studied. In this research, a visual experiment was used to develop the prediction model of water bridge shape. Based on the visual experiment, the contact line and the contact angles of water bridge were measured, covering various water volumes, solid plate separations and five different solid materials. The prediction model of contact line via correlated aspect ratio was developed, and the prediction model of contact angles via the correlated maximum and minimum contact angles was proposed. The mean deviation of aspect ratio of contact line was 3.4% and that of contact angles was 7.9%.

    Effect of evaporation temperature on boiling heat transfer in horizontal ribbed and embossing finned tube pool
    ZHANG Jili, CHEN Jingdong, MA Zhixian, WANG Yonghui
    2016, 67(6):  2230-2238.  doi:10.11949/j.issn.0438-1157.20151641
    Abstract ( 80 )   PDF (1139KB) ( 233 )  
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    Under a promotion of energy conservation and emission reduction, efforts on research and development of the technologies related to boiling heat transfer enhancement of outer tube have been conducted extensively. In this article, a testing system for boiling heat transfer outside the horizontal double-side enhanced tubes was established. Using R134a as a cyclic working medium, the effect of evaporation temperature on the characteristics of boiling heat transfer in three-dimensional ribbed and embossing finned tube under conditions of varied heat flux was investigated, on basis of which theoretical descriptive method was discussed. It showed that, the curve slope of evaporation heat transfer coefficient as a function of evaporation temperature is non-linearly related to the heat flux. At the same evaporation temperature, it shows a monotonic increase in the heat transfer coefficient on tube surface with the heat flux, of which the slope gradually decreases with the heat flux. By means of regression analysis, an unified formula for the heat transfer coefficient on ribbed and embossing finned tube surface as a function of evaporation temperature under conditions of varied heat flux was achieved. Under operation condition of the same heat flux, the factor of heat transfer enhancement approaches 1, exceeds 2, and reaches the maximum 2.588 at 5, 10 and 20 kW·m-2 of heat flux, respectively. The mechanism and theoretic description of the heat transfer coefficient on ribbed and embossing finned tube surface as functions of evaporation temperature and heat flux, need to be further studied.

    Characteristics of velocity and thickness distribution of liquid film in vertical falling tube
    WANG Jing, WANG Yifei, YAN Liucheng, WU Ziwei, YU Guangsuo
    2016, 67(6):  2239-2245.  doi:10.11949/j.issn.0438-1157.20151953
    Abstract ( 107 )   PDF (792KB) ( 317 )  
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    The flow characteristic of the falling liquid film in the scrubbing-cooling tube was researched in this paper. The ultrasound Doppler velocimetry was adopted to measure the velocity and thickness distribution of the liquid film non-instrusively at different circumferential and axial position. The Reynolds number ranged from 1.0×104 to 3.1×104. The results showed that both the velocity and thickness of the liquid film were the largest at the 0° position, leading to unevener thickness distribution and the separation of the local liquid film and the sharp increase of the liquid film thickness at the 8° and 16° positions. In the axial direction, because of the effect of gravity, the liquid film velocity increased with the increase of flow distance when the Reynolds numbers was less than 2.0×104, whereas, it decreased at large Reynolds numbers since that the resistance became a dominant factor. Both of the thickness and velocity of global liquid film increased with increasing Reynolds number. Furthermore, the increase of the Reynolds numbers made the liquid film more unstable.

    Simulation of gas-liquid two-phase flow for airlift ceramic membrane filtration process
    LIN Jin, SHEN Hao, JING Wenheng
    2016, 67(6):  2246-2254.  doi:10.11949/j.issn.0438-1157.20151560
    Abstract ( 99 )   PDF (2454KB) ( 307 )  
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    The influences of aerator aperture size and aeration rate on the gas hold-up, liquid circulation velocity, wall shear stress and turbulence intensity in a novel airlift ceramic membrane filtration equipment containing a 19-channel ceramic membrane was investigated by the CFD simulation. Further, the VOF model was adopted to simulate the flow state of the gas-liquid two-phase fluid and the mean error between experiment date and simulation date was 5%-10%. The results demonstrated that the gas hold-up increased with increasing aeration rate and decreasing aerator aperture size. The liquid circulation velocity, wall shear stress and turbulence intensity increased with increasing aeration rate, and the increasing trend became slow after the aeration rate reached 400 L·h-1. For the three aperture aerator with different size, the comparison of experiment and simulation results have indicated that the liquid circulation velocity was only related to the aeration rate, and had little to do with aerator aperture size. Decreasing of the aerator aperture size was conductive to the increasing of the wall shear stress and the filtration process.

    Flow boiling heat transfer characteristic of refrigerant R1234ze(E) in horizontal circular tube
    QIU Jinyou, ZHANG Hua, YU Xiaoming, WANG Xi, WU Yinlong
    2016, 67(6):  2255-2262.  doi:10.11949/j.issn.0438-1157.20151523
    Abstract ( 130 )   PDF (836KB) ( 303 )  
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    Nowadays, more and more attention has been paid to the new low GWP (global warming potential) refrigerant R1234ze(E), which is one of the ideal alternatives for R134a. In this work, the flow boiling heat transfer coefficients of R1234ze(E) and R134a were measured inside an 8 mm ID horizontal tube. The experimental results were obtained over the saturation temperature of 10℃ with heat fluxes ranging from 5.0 to 10.0 kW·m-2 and mass fluxes ranging from 300 to 500 kg·m-2·s-1. The influences of mass flux, heat flux and quality on the heat transfer coefficients were discussed. The results showed that the local flow boiling heat transfer coefficients of R1234ze(E) and R134a increased with increasing mass flux and heat flux. The local heat transfer coefficient of R1234ze(E) was around 14.68% lower than that of R134a at the mass flux of 300 kg·m-2·s-1, while the local heat transfer coefficient deviation between R1234ze(E) and R134a reduced to 7.35% when the mass flux reached 500 kg·m-2·s-1. Additionally, the experimental data of local heat transfer coefficients were compared with four well-known correlations available in literatures. The results indicated that Kandlikar correlation provided the best prediction of the local heat transfer coefficients for both R1234ze(E) and R134a. Approximately 90% of the experimental points are in an error bandwidth of ±25% of the prediction, and the average deviations are found to be 23.13% and 11.50% for R1234ze(E) and R134a, respectively.

    Start-up and heat transfer performance of micro-grooved oscillating heat pipe
    LI Xiaojun, QU Jian, HAN Xinyue, WANG Qian, LIU Feng
    2016, 67(6):  2263-2270.  doi:10.11949/j.issn.0438-1157.20151913
    Abstract ( 78 )   PDF (3484KB) ( 180 )  
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    The start-up and heat transfer performance of a micro-grooved tube oscillating heat pipe (OHP) and three other smooth tube OHPs were experimentally investigated and compared both at vertical and horizontal orientations. Deionized water was used as the working fluid with a volumetric filling ratio of 50%. The internal diameters (IDs) of three smooth tube OHPs were 3.4 mm (1#), 4.0 mm (2#) and 4.8 mm (3#), respectively, and the internal hydraulic diameter of the micro-grooved OHP was about 2.82 mm. The results showed that at the vertical bottom heat mode, the micro-grooved OHP had lower heating power input and average evaporator temperature as compared to other smooth tube OHPs. At a heating power input of about 305 W, the reductions in the thermal resistance of the micro-grooved tube OHP were about 41.7%, 35.6% and 30.9% as compared to that of the 1#, 2# and 3# OHPs, and the corresponding reductions in the evaporator temperature were about 12.1℃, 11.8℃ and 7.6℃, respectively. At the horizontal orientation, only the micro-grooved OHP could start up favorably at the relatively low heating power inputs within all these four tested OHPs and indicated better heat transfer performance. According to a qualitative analysis, the heat transfer enhancement of the micro-grooved OHP was mainly attributed to the sensible/latent heat transfer intensification as well as enhanced liquid backflow to the evaporator due to the microgroove-induced capillary action.

    Heat transfer property of lauryl alcohol-capric acid-nanoparticle composite phase change materials
    HUANG Yan, ZHANG Xuelai
    2016, 67(6):  2271-2276.  doi:10.11949/j.issn.0438-1157.20151968
    Abstract ( 153 )   PDF (450KB) ( 234 )  
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    To increase the thermal conductivity of organic phase change materials, the nanoparticles with high thermal conductivity, including multi-walled carbon nano-tubes (MWNTs), Cu and Al2O3, were added into the organic composite PCMs of lauryl alcohol-capric acid (with mass ratio of 58.47:41.53), respectively. The thermal conductivity coefficients of nano-organic composite PCMs were analyzed. The kinds and concentration of nanoparticles and the time of ultrasonic dispersion were the key influencing factors. The results showed that the thermal conductivity increased in different degree when the different mass fractions of MWNTs, Cu and Al2O3 were added. The thermal conductivity enhancement effects were in order of MWNTs, Al2O3 and Cu when mass fraction was 0.1 g·L-1 and ultrasonic dispersion time was 50 min. With the same kind of nanoparticles and ultrasonic dispersion time, the thermal conductivity enhancement effects were decreased as mass fraction was increased from 0.1 g·L-1 to 0.6 g·L-1. Excellently, compared with the original PCMs, the thermal conductivity increased by 20.5% when mass fraction of MWNTs was 0.1 g·L-1 and ultrasonic dispersion time was 90 min. The lauryl alcohol-capric acid+MWNTs (0.1 g·L-1) + sodium dodecyl bezene sulfonate (0.2 g·L-1) with good thermal stability had a limited influence on the phase change temperature of the original PCMs and decreased the degree of supercooling by 58.7%.

    Distribution of local void fraction for subcooled boiling flow in rolling circular tube
    BAO Wei, CHEN Bingde, XU Jianjun, XIE Tianzhou, HUANG Yanping
    2016, 67(6):  2277-2283.  doi:10.11949/j.issn.0438-1157.20151372
    Abstract ( 70 )   PDF (1027KB) ( 107 )  
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    Subcooled boiling flow exists in many technical applications of process and engineering such as nuclear reactors, steam generators and refrigeration systems. Accurate prediction of local void fraction is of significance for establishment of two-phase flow mathematical model and estimation of pressure loss and heat transfer capability. The radial local void distribution of subcooled boiling flow under rolling conditions was experimentally investigated by double-sensor optical probe, of which the transient local void fraction was obtained by periodical accumulation method. It showed that the local void distribution under rolling conditions exhibited a periodic variation, where the peak void fraction appeared in near-core region and near-wall region of the circular tube, and the largest amplitude of local void fluctuation existed in the near-wall region. Different from that under static conditions, the spatial distribution of local void fraction changed with the time within a rolling period. Furthermore, the period and amplitude rolling influence the distribution of local void fraction.

    Particle size characterization based on ultrasonic impedance spectrum
    JI Xiaoming, SU Mingxu, WANG Xue, CAI Xiaoshu
    2016, 67(6):  2284-2290.  doi:10.11949/j.issn.0438-1157.20151954
    Abstract ( 103 )   PDF (1343KB) ( 394 )  
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    The purpose of this paper is to explore the relationship between the characteristics of particles and ultrasonic impedance spectra. Although the ultrasonic attenuation and velocity spectra methods are becoming the sophisticated technology for particle size characterization, they are not available in some actual projects, either because the particulate matters to be investigated are too dense or because there are some bubbles inside. However, ultrasonic impedance spectra technology emerges as a potential technique to provide a non-destructively detecting way in the aforementioned occasions. By modifying the ultrasonic attenuation spectral model, the theories related the ultrasonic impedance spectra to particle concentration and size are established to implement quite a few numerical simulations, showing that the acoustic impedances of particles is sensitive to the changes in particle concentration and size. After that, three kinds of polystyrene suspensions with different volume median diameters (7.69 mm, 21.58 mm and 66.64 mm) are investigated experimentally using the transducers with center frequencies varied from 10 MHz to 100 MHz. The results are quantitatively validated by the theory whereby a conclusion can be yielded that it is possible to distinguish the particles with different sizes by using ultrasonic impedance spectra. The comparison of the inversion results and image analysis indicates that the impedance technique is available to particle size characterization.

    Transient characteristics of compressible gas jet in liquid
    WANG Chao, SHI Honghui, WANG Jianfeng
    2016, 67(6):  2291-2299.  doi:10.11949/j.issn.0438-1157.20151874
    Abstract ( 109 )   PDF (12317KB) ( 517 )  
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    A device of submerged supersonic gas jet is configured and a two-dimensional axis-symmetric model of two-phase flow is established via volume of fluid (VOF) method. The flow field of the submerged supersonic gas jet is experimentally visualized using a photographic technique which allows simultaneous analysis of the jet interface to investigate the behavior of gas jets injected into water ambient. The detailed internal structure of the flow field is obtained by numerical technique via finite volume method (FVM). The results show that the flow field from the nozzle exit to the far away field of downstream includes three different characteristic regions: the jet region, the transition region and the plume region. The gravity can be ignored in jet region. And the bulge and back-attack phenomena lead to the heavy oscillation flow pattern. Gas-liquid interface instabilities cause jet necking phenomena which leads expand or pinch-off of the gas jet and subsequent bulge and back-attack phenomena. A small scale of the necking results in the bulge phenomenon at upstream. A slightly larger scale of the necking causes the back-attack phenomenon. A large scale of necking even leads to the jet pinch-off phenomenon and then jet rebuilding.

    Numerical simulation of bubble coalescence behavior in contact zone of dissolved air flotation tank
    CHEN Aqiang, WANG Zhenbo, WANG Chen, YANG Jiajia, JIN Youhai
    2016, 67(6):  2300-2307.  doi:10.11949/j.issn.0438-1157.20151664
    Abstract ( 138 )   PDF (2349KB) ( 387 )  
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    Bubble coalescence can make the increase of bubble size in the contact zone of the dissolved air flotation tank, which will finally influence the separation efficiency. Population balance model was employed to study bubble coalescence behavior in the contact zone. With this numerical method, the bubble coalescence mechanism and effect of mainstream and recycle flow rates on coalescence phenomenon were studied. At first, Schiller-Naumann, Grace and Tomiyama drag coefficient models were included in the simulation process, respectively. The results showed that the bubble sizes simulated with these three models were similar with good accordance with the experimental data. Schiller-Naumann was adopted in the following simulation as its computational cost was lower than Grace and Tomiyama model. By comparing the bubble size distribution with velocity profile, high velocity gradient was detected at the upstream and downstream flow transition region around the recycle flow inlet. The high velocity gradient was proved to be the key factor causing bubble coalescence. At last, the influence of mainstream and recycle flow rates on bubble size was investigated. Bubble size in the contact zone increased with the increase of recycle flow rate because the velocity gradient at upstream and downstream transition region increased, which can enhance the bubble coalescence. On the contrary, mainstream flow rate showed no effect on bubble size distribution in the contact zone.

    Motion and distribution of gas-solid two-phase flow in elbow with two-phase deflector
    PAN Xiaohui, MA Chunyuan, CUI Lin
    2016, 67(6):  2308-2317.  doi:10.11949/j.issn.0438-1157.20151633
    Abstract ( 75 )   PDF (6680KB) ( 216 )  
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    In view of the problem that gas-solid two-phase flow is not evenly distributed in the elbow of the entrance of flue gas pollutants removal system in the coal-fired power plant,a new two-phase deflector structure was put forward. CFD numerical simulation was employed to analyze the uniform effect of two-phase deflector and conventional deflector. The effect of the two-phase deflector on the distribution law of flow velocity and particle mass, and the effect of the plate shape and the plate angle on the uniform effect of two-phase deflector were simultaneously studied. Finally, the optimum structure of the two-phase deflector was obtained by the Design-Expert response surface method and CFD. The optimal structure was applied to the industrial test and the final result of the calculation and industrial test data were compared. The results showed that it is better to install two-phase deflector than deflector or delta wing baffle in the elbow because of the more uniform distribution and lower pressure drop. The flow velocity distribution and the particle mass concentration distribution changed gradually with the increase of the angle between the plates and the pressure drop of the elbow increased with the angle between the plates too. The optimum structure was the two-phase deflector with the angle of 75.49°and straight plate type. The comparison between the simulation and field measurements showed good agreement. The numerical simulation method proposed by this paper can be used to calculate gas-solid flows in the ESP inlet elbow with complex internal structure in detail.

    Super-wettability meshes enhance movement of gas-liquid interface
    CHEN Hongxia, MA Fumin, HUANG Linbin
    2016, 67(6):  2318-2324.  doi:10.11949/j.issn.0438-1157.20151827
    Abstract ( 68 )   PDF (2377KB) ( 397 )  
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    Using the porous materials to guide and separate multi-phase flow became a leading edge topic. The mechanism is the force balance of three-phase interface, in which the wettability of substrate is the key factor. An adiabatic and visible experiment flat form was built to study the effect of wettability on the phase interface movement and the separation with a super-hydrophobic and a super-hydrophilic mesh. As the result, the super-hydrophobic and super-hydrophilic mesh showed the self-compatibility. With this ability the super-hydrophilic mesh can block bubbles from flowing through, while the super-hydrophobic mesh can hold a column of liquid by counteracting gravity. Base on the stagnant experiment the super-hydrophobic mesh with a contact angle of 151° showed a resistance of 117.6 N·m-2 to water, and the super-hydrophilic mesh (θ=0°) indicated a resistance of 49 N·m-2. During the two-phase flow experiment, the super-hydrophobic mesh showed an enhancement on separation of bubbles, while the super-hydrophilic mesh refused the penetration of bubbles with a layer of liquid film. A mathematic relation of self-compatibility of mesh and the critical diameter of separation was concluded. The modulation of wettability of porous mesh can promote the phases separating which will widen their applications on phase change heat transfer fields.

    MOF-templated preparation of porous Au/CuxO catalysts with octahedral structures for CO oxidation
    LIU Pengfei, ZHANG Suoying, YANG Zhuhong, LU Xiaohua
    2016, 67(6):  2325-2331.  doi:10.11949/j.issn.0438-1157.20160002
    Abstract ( 130 )   PDF (7785KB) ( 560 )  
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    More recently, metal-organic frameworks (MOFs), as a excellent sacrificial template, have been widely used to fabricate a variety of porous metal oxides with special structures and performances. To take full advantage of MOFs in composition regulation, herein a novel method to prepare porous Au/CuxO composites with octahedral structures inherited from MOFs was introduced. Au/Cu-BTC was firstly prepared by the traditional deposition-precipitation method. Subsequently, pyrolysis of Au/Cu-BTC was conducted in 2% (volume fraction) O2 balanced with helium. By varying the time of heating, Au/CuxO composites including Au/Cu2O, Au/Cu2O-CuO and Au/CuO were successfully achieved. When tested in CO oxidation, these supported catalysts exhibited much better catalytic performances than Cu-BTC and Au/Cu-BTC due to the more active support of metal oxides. Thus, Au/Cu2O showed the best catalytic activity since the high surface area, Cu2O content and better dispersion of Au.

    Electrochemical reduction of dechlorination of pentachloropyridine to 2,3,5,6-tetrachloropyridine over zinc-based catalyst: reaction mechanism and process optimization
    CHEN Zewei, WANG Yixiang, DING Xufen, XU Yinghua, MA Chun'an
    2016, 67(6):  2332-2339.  doi:10.11949/j.issn.0438-1157.20151444
    Abstract ( 63 )   PDF (694KB) ( 164 )  
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    The electrochemical dechlorination mechanism of pentachloropyridine (PCP) to 2,3,5,6-tetrachloropyridine (2,3,5,6-TCP) on stainless steel cathodes in an acetonitrile/water mixed solution containing ZnCl2 was investigated by cyclic voltammetry and constant potential electrolysis methods. Moreover, an optimization of various operating conditions under constant potential electrolysis for the dechlorination process was performed in an H-cell. It showed that indirect electrochemical dechlorination using Zn/Zn2+ as the redox mediator is the main pathway of PCP to 2,3,5,6-TCP. The 0.08 mol·L-1 PCP could be selectively dechlorinated to 2,3,5,6-TCP with 88.7% yield and 59.1% of current efficiency under optimum conditions (catholyte: an acetonitrile solution containing 0.025 mol·L-1 HCl, 15%(vol) water, 0.2 mol·L-1 sodium benzenesulfonate and 0.16 mol·L-1 ZnCl2, and 1.25 A·dm-1 of current density).

    Preparation of mesoporous silica microsphere supported ruthenium catalysts for asymmetric transfer hydrogenation of acetophenone
    XU Xiaoning, CAO Fahai
    2016, 67(6):  2340-2348.  doi:10.11949/j.issn.0438-1157.20151895
    Abstract ( 85 )   PDF (2825KB) ( 210 )  
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    Supported ruthenium catalyst, complexes of TsDPEN supported with mesoporous silica microspheres of various morphologies and structures, which were synthesized by a simple one-step in situ polymerization- induced precipitation procedure, were prepared for the asymmetric transfer hydrogenation of acetophenone. The mesoporous structure of silica microspheres were observed by the nitrogen adsorption/desorption isotherms and field emission scanning electron microscopy (FESEM), ruthenium complex well distributed on silica microspheres by transmission electrum microscopy (TEM), and the existence of hydrogen bonds between catalyst and regents by infrared spectrometry (IR). Effect of support structure and reaction conditions such as reaction temperature and time, and reactant concentration on catalytic performances for the asymmetric transfer hydrogenation of acetophenone were investigated. It showed that the interaction between ruthenium complexes with supports of small pore size and high specific surface area promoted the asymmetric transfer hydrogenation and channel stereo-confinement of mesoporous silica microspheres, resulting in significant enhancement of the activity and optical selectivity of the reaction. Under the optimum of 40℃, 16 h and 0.2 ml acetophenone of reaction conditions, the catalyst achieved its highest 64.1% and 93.4% of acetophenone conversion and enantio selectivity of R-α-phenethyl alcohol for asymmetric transfer hydrogenation of acetophenone, respectively.

    Desolvation kinetics of sulfadiazine N-methylpyrrolidone solvate
    SUN Jia, LI Xiang, BAO Ying, ZHANG Meijing, HOU Baohong, YIN Qiuxiang
    2016, 67(6):  2349-2354.  doi:10.11949/j.issn.0438-1157.20151822
    Abstract ( 114 )   PDF (2222KB) ( 246 )  
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    Sulfadiazine N-methylpyrrolidone solvate (SD-NMP) was prepared by solution crystallization method. The molar ratio of sulfadiazine (SD) to N-methylpyrrolidone (NMP) in the solvate was 1:2 from the calculation of thermal gravimetric data. The desolvation bebavior of SD-NMP solvate was investigated by thermal gravimetric analysis, hot stage microscopy, scanning electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. According to the same crystal habit and crystal form between the desolvation product of SD-NMP solvate and sulfadiazine crystal, it can be known that the formation and desolvation of SD-NMP solvate was a reversible transformation process. The desolvation kinetics of SD-NMP solvate under temperature of 70℃, 75℃, 80℃ and 85℃ was studied by use of the model fitting method according to the different reaction models. The results showed that the most appropriate model was the geometrical contraction one, and the desolvation of SD-NMP solvate was attributed to phase boundary reaction and the rate-limiting step was the inward advance of the phase boundary from the surface to the center of the crystals. The above research results were consistent with the WET3 theory.

    Decarbonization reaction kinetics of MDEA and MEA
    TANG Jianfeng, ZHANG Guojun, SHI Zelin, HUANG Bin, WANG Yue, ZHAO Mingyu
    2016, 67(6):  2355-2362.  doi:10.11949/j.issn.0438-1157.20151480
    Abstract ( 147 )   PDF (660KB) ( 308 )  
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    Based on the small reaction kettle experiment device, the data approximation could be adopt to establish the kinetics model by two-film theory. Then the reaction kinetics of amine solutions of MEA (monoethanolamine), MDEA (methyldiethanolamine) and both mixtures were analyzed by the model. The reaction kinetics models of MEA and MDEA, which was established by pseudo-first-order reaction, could forecast gas-liquid mass transfer performance of them well after experimental verification. The result showed that the interaction coefficient and mass transfer rate of MEA was higher than that of MDEA. The mass transfer rates decreased with the process of reaction. In addition, the apparent propagation rate constant and enhancement factor of mixed amine increased with the increasing temperature and the ratio of MEA. At last, it forecasted that the mixed amine of MDEA+MEA (2 mol·L-1+1 mol·L-1) had the better decarbonization performance, which had higher mass transfer rate with its enhancement factor of 0.5.

    Preparation of amorphous Ni-B/graphene composites for catalytic hydrogenation of pinene
    ZHANG Jiahua, JIANG Lihong, WU Shuisheng, WANG Hongqin, WANG Yaming
    2016, 67(6):  2363-2370.  doi:10.11949/j.issn.0438-1157.20151703
    Abstract ( 98 )   PDF (3906KB) ( 232 )  
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    Graphite oxide was prepared from flake graphite by Hummers method and dispersed by ultrasonic treatment. The amorphous Ni-B/rGO composite catalysts were prepared by one-step chemical reduction with NaBH4 as reducing agent, and tested in the catalytic hydrogenation of pinene as the probing reaction. It shows that the as-prepared catalysts exhibit high catalytic activity and relatively high enantioselectivity of 96.5% for cis-pinane, which is better than the traditional Raney nickel and even noble metal catalysts. The catalyst possessed good stability, evidenced by that after 8-times testing cycles, both the conversion of pinene and the enantioselectivity to cis-pinane remained at a good level. The structure and properties of amorphous Ni-B/rGO composite catalysts were measured by XRD, XPS, TEM techniques, and the relationship between the catalytic performance and the structure was explored. The higher activity of the Ni-B/rGO amorphous catalyst could be attributed to the highly uniform dispersion of the Ni-B active species with unique electronic structure, and the interaction between Ni-B active species and the rGO in the composite catalysts.

    Simulation, experimentation and analyzation of vacuum pressure swing adsorption process for CO2 capture from dry flue gas
    YAN Haiyu, FU Qiang, ZHOU Yan, LI Dongdong, ZHANG Donghui
    2016, 67(6):  2371-2379.  doi:10.11949/j.issn.0438-1157.20151503
    Abstract ( 155 )   PDF (611KB) ( 195 )  
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    This paper firstly conducted the experiments of CO2 capture from flue gas by vacuum pressure swing adsorption (VPSA) based on the two-bed experimental set-up using industrial silica as adsorbent. The mathematical model of VPSA process was built in gPROMS and its validity was well verified by comparing the results of simulation with experiment. The concentration of CO2 can be enriched to 74% from 15% with recovery of 91.52% by the two-bed VPSA process. Based on the model, the relationship of product concentration, recovery, energy consumption of CO2 with feed flowrate, adsorption time and blowdown pressure was investigated. The influence of bed pressure and feed flowrate on compressor energy consumption was also studied. Results showed that the concentration of CO2 can be enriched significantly by increasing feed flowrate, extending adsorption time and decreasing counter-blowdown pressure, but all of them were companied with reduction in recovery and the former two led to a higher energy consumption. The higher in adsorption pressure and larger in feed flowrate, the more energy will the compressor consumed.

    Preparation of bromine modified metal-organic frameworks for element mercury adsorption
    ZHANG Xiao, SHEN Boxiong, CHI Guilong, ZHU Shaowen, WANG Zeyi
    2016, 67(6):  2380-2385.  doi:10.11949/j.issn.0438-1157.20151730
    Abstract ( 138 )   PDF (538KB) ( 318 )  
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    Bromine modified metal organic framework (MOF) was synthesized by solvothermal method for element mercury (Hg0) adsorption. The crystal structure, chemical and texture properties of the modified MOF were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 adsorption. Covalent bromine was detected on the surface of the modified MOF and the modification process resulted in a lower specific surface area and total pore volume than those of unmodified MOF. Hg0 removal efficiencies increased with temperature for both modified MOF and un-modified MOF sorbent. In the dynamic adsorption experiments, which were conducted trying to mimic the flue gas condition, the bromine modified MOF showed a high Hg0 removal efficiency of above 95% for 10 h at 240℃, while the efficiency dropped to 75% within 5 h for both unmodified MOF and traditional active carbon sorbent.

    Preparation of AC/X-G adsorbent and CH4/N2 adsorption separation performance
    ZHANG Dongmei, CHENG Wenping, ZHANG Mingsheng, CUI Xingyu, MA Jinghong, LI Ruifeng
    2016, 67(6):  2386-2392.  doi:10.11949/j.issn.0438-1157.20151606
    Abstract ( 114 )   PDF (3264KB) ( 245 )  
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    The 13X/activated carbon composite was treated by 0.2 g·ml-1 glucose solution for carbon deposition. The effect of deposition times on the pore structure, surface properties and separation performance of CH4/N2 were studied. The crystalline, pore structure and surface properties of the samples were investigated by X-ray diffraction (XRD), N2 adsorption-desorption isotherms at 77 K, scanning electron microscopy (SEM), CO2-TPD and Fourier transform infrared spectrum (FT-IR). The adsorption isotherms of CH4 and N2 were tested at 298 K and 100 kPa,and compared with the adsorption separation properties of carbon materials and 13X zeolite reported in the literatures. The experimental results showed that the relative content of X zeolite, the micropore surface area and the micropore volume of AC/X-G were gradually decreased with the increase of deposition times. The surface of samples was covered by carbon membrane, which led to decrease of the alkaline functional groups but increase of containing C-O groups. The adsorption capacities of CH4 and N2 decreased, while the adsorption separation coefficient was improved. After third deposition, the adsorption separation coefficient of CH4/N2 reached 3.0. The oxygen-containing functional groups on the surface of AC/X-G were beneficial to improve the separation performance of CH4/N2.

    Molecular simulation on separation of CO2/CH4 gas mixture with carbon membrane
    ZHAO Haohan, PAN Yanqiu, HE Liu, YU Lu, WANG Tonghua
    2016, 67(6):  2393-2400.  doi:10.11949/j.issn.0438-1157.20151747
    Abstract ( 128 )   PDF (1656KB) ( 554 )  
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    A simulation study was conducted in separation of CO2/CH4 gas mixture using Materials Studio and Lammps softwares, respectively. Zigzag-type pore model was developed to describe the pore structure and verified by CO2 adsorption isotherm experimentally determined with home-manufactured carbon membranes. Adsorption and diffusion behaviors of pure gas and gas mixture within the pores of carbon membrane were investigated under different conditions in an effort to explore the separation mechanism. Overall separation coefficient of CO2/CH4 adsorption and diffusion was examined in the present study. Results showed that appropriately low temperature and small pore size were beneficial to achieve separation of CO2/CH4 gas mixture. As the temperature and the pore size were decreased, the separation coefficient increased. The overall separation coefficient of gas mixture was 20.1 at 298 K of the operating temperature and 0.670 nm of the pore size of membrane, which was consistent with the experimental value. This fundamental research would provide a basis for optimizing the preparation of carbon membranes and for studying the separation mechanism of CO2/CH4 gas mixture.

    Preparation and properties of oxidized regenerated cellulose by hydrogen peroxide
    ZHANG Shuidong, WANG Peng, WU Rongxing, PENG Huaqiao, WU Ronglan
    2016, 67(6):  2401-2409.  doi:10.11949/j.issn.0438-1157.20151620
    Abstract ( 122 )   PDF (2536KB) ( 453 )  
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    Hydrogen peroxide was used to oxidize pretreated regenerated cellulose to oxidized regenerated cellulose (OGC) with carboxylic content (CC) ranging from 3.2% to 15.6% depending on the H2O2/cellulose molar ratios used, reaction time and the pH. The structure of OGC was characterized by FT-IR, 13C NMR, SEM,BET and XRD. The results revealed that the primary hydroxyl at C6 site in glucose units of regenerated cellulose was selectively oxidized to carboxyl group by H2O2 at the present of copper sulfate, and the notable characteristic peaks of carboxyl groups appeared at 173±2 in the spectra of 13C NMR. SEM revealed that the pretreated regenerated cellulose by alkali solution would increase the fiber diameter and grooves space, resulting in volume expansion of cellulose, and thereby promoting oxidation reaction. BET surface area (SBET) and adsorption pore volume (Vp) of OGC 15.6 increased from 10.12 m2·g-1 to 62.45 m2·g-1 and 0.0152 cm3·g-1 to 0.0183 cm3·g-1, respectively. The crystallinity of OGC showed increasing with the increase of CC, which was due to partial loss of the disordered regions during the washing process because of their increased water-solubility. By TG, there was a reduction in thermal stability in parallel with the increase in CC of the samples, while exhibited high char yields. These changes could be attributed to a reduction in degree of polymerization and the increment of CC. The results demonstrated that the cellulose was selectively oxidized to carboxyl group by H2O2, and the properties of OC were depended on the CC. The effect of carbonization agent type on the flame retardant properties of MFAPP/EP was investigated. It revealed that when OGC15.6 (6.25%) acted as carbonization agent, the epoxy resin achieved a UL-94 V0 classification with LOI of 27.2%. The flame retardant properties of MFAPP/EP by OGC15.6 were better than those of GC and pentaerythritol. The adsorption capacity of OGC for Cu2+ and Pb2+ ions from aqueous single metal solutions was obtained by analyzing concentration determined by atomic absorption spectroscopy. These samples showed maximum adsorption capacities for Cu2+ and Pb2+ ions ranging from 4.894 to 24.426 mg·g-1 and 5.845 to 71.833 mg·g-1, respectively. The OGC15.6 showed larger maximum adsorption capacities than GC. The result illuminated that OGC could be applied to flame retardant EP and metal ions adsorption due to the introduction of carboxylic group.

    Preparation and adsorption properties of lysozyme molecularly imprinted polylactide microsphere
    TANG Zhimin, MA Xinbin
    2016, 67(6):  2410-2416.  doi:10.11949/j.issn.0438-1157.20160176
    Abstract ( 97 )   PDF (2185KB) ( 198 )  
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    Lysozyme molecularly imprinted modified polylactide microsphere (LZY-MIP-MPLA) was prepared by sol-gel using modified polylactide microsphere as carrier, 2,3-epoxypropoxy propyltrimethoxysilicane as the functional monomer and tetraethyl orthosilicate as crosslinker. The prepared material was characterized by infrared spectroscopy and scanning electron microscopy. The preparation conditions were optimized. The adsorption properties of LZY-MIP-MPLA on lysozyme were studied in detail, and the influence of pH and NaCl on adsorption property was also investigated. The results showed that the adsorption capacity of LZY-MIP-MPLA on lysozyme was better than that of NIP-MPLA, and it needed 200 min to reach the equilibrium. By the analysis of Scatchard equation, the interactions of imprinted cavities and template molecule were not exactly equivalent and there existed two kinds of interaction places. The separation factor of LZY-MIP-MPLA on lysozyme and bovine albumin was 10.13, showing that LZY-MIP-MPLA displayed high recognition ability to the template molecule LZY.

    Flow characteristic of supersonic gas separator with diversion cone
    HU Dapeng, WANG Yingguang, REN Wenwen, ZHAO Jianhua, LIU Peiqi
    2016, 67(6):  2417-2425.  doi:10.11949/j.issn.0438-1157.20151817
    Abstract ( 109 )   PDF (7822KB) ( 170 )  
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    The two-dimensional axial model is adopted to study the flow characteristic in supersonic nozzle using ideal gas as medium. Experimental platform is set up to study the influence of structural and operating parameters on flow field and separation efficiency under low pressure ratio. The numerical results indicate that there is no shock wave in the nozzle divergent section when pressure ratio is 1.4, outer angles of liquid discharge chamber is less than 12° and area ratio is 1.27. Meanwhile, the analysis of the leading shock waves indicates that the reverse compression waves appear in the liquid discharge chamber and move to nozzle upstream. The experimental results show that the highest separation efficiency of the supersonic gas separator (SGS) can reach 20.5% when the pressure ratio and area ratio are set to 1.4 and 1.27, respectively.

    Stratification phenomenon and laws of wax deposits of waxy oil triggered by asphaltene addition
    LI Chuanxian, CAI Jinyang, CHENG Liang, YANG Fei, ZHANG Haoruo, ZHANG Ying
    2016, 67(6):  2426-2432.  doi:10.11949/j.issn.0438-1157.20151723
    Abstract ( 125 )   PDF (3787KB) ( 281 )  
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    Stratification phenomenon and laws of wax deposits were studied for oil samples 1 (without asphaltene) and 2 (0.75%(mass) asphaltene) with the same wax content using the Couette wax deposition device. In the study of stratification phenomenon of wax deposits, the macroscopic morphology, DSC curves, amount of precipitated wax and wax crystal microcosmic morphology of the outer and inner deposits of oil samples 1 and 2 were analyzed. It was found that the deposit of oil sample 1 had no obvious stratification while that of oil sample 2 had obvious stratification, proving that the asphaltene led to the stratification of wax deposit. Compared with outer deposit, the WAT, amount of precipitated wax and asphaltene content of inner deposit of oil sample 2 increased significantly. It was found in the study of stratification laws of wax deposits that the outer wax deposition mass decreased with the increase of the temperature of wax deposition barrel, the temperature difference of oil and wax deposition barrel and the rotate speed of oil sample barrel, while the inner one deceased with the increase of the temperature of wax deposition barrel and increased with the temperature difference of oil and wax deposition barrel and the rotate speed of oil sample barrel. The total wax deposition mass deceased with the increase of the temperature of wax deposition barrel and the rotate speed of oil sample barrel, and increased firstly then decreased with the increase of the temperature difference of oil and wax deposition barrel.

    Determination of metastable zone width and induction period of L-tartaric acid aqueous solution
    LENG Yixin, TAN Qian, HUANG Chunxiang, WANG Jun, SHAO Hui
    2016, 67(6):  2433-2439.  doi:10.11949/j.issn.0438-1157.20151174
    Abstract ( 88 )   PDF (496KB) ( 358 )  
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    The crystallization metastable zone width and induction period of L-tartaric acid in water were measured by laser method at the temperature range of 20-60℃. The influences of saturation temperature, cooling rate and agitation rate on the metastable zone width and the effect of supersaturation on the induction period were explored, respectively. The results showed that the crystallization metastable zone width became narrow with rising saturation temperature and agitation rate, and decreasing cooling rate. The apparent nucleation series m and the nucleation rate equation were given. Furthermore, the experimentally measured crystallization induction period decreased with increasing supersaturation S. The solid-liquid interfacial tension of L-tartaric acid in water was calculated at 20℃ and 25℃ on basis of the classical nucleation theory and induction period data.

    Carbon capture by ammonia with reinforced crystallization
    LENG Hao, GAO Jianmin, ZHANG Yu, LIU Qi, FENG Dongdong, DU Qian, WU Shaohua
    2016, 67(6):  2440-2448.  doi:10.11949/j.issn.0438-1157.20151729
    Abstract ( 102 )   PDF (801KB) ( 274 )  
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    In response of problems such as ammonia escape, high regenerated energy and low absorbed rate in the late stage, which exist in the research of carbon capture by ammonia now, this paper presents a novel process of carbon capture by ammonia with reinforced crystallization, using a new type of aqueous ammonia-ethanol mixing absorbent. The effect of absorption and crystalline regularity under different absorbent ingredients, different absorption temperatures, different flue gas flow, and different CO2 volume fraction is studied using a semi-continuous bubbling reaction system. The experimental results show that mixing absorbent with relatively high ratio of ethanol, relatively low absorption temperature, and higher gas flow and larger volume fraction of CO2 will be favorable for strengthening of process, including that the appearing time of crystals in the absorbent could bring forward and the ratio of ammonia account in the crystals to the initial total ammonia could be up to 38.75% as well as the CO2 absorption capacity was improved significantly compared to pure aqueous ammonia. Novel ideas presented in this paper could be that a carbon capture process by ammonia with reinforced crystallization is suggested, and better conditions were given for improving absorption and reducing consumption of desorption energy. All basic data and results provided by this paper could be useful for further study of this new process.

    Characteristic and structure of calcium sulfate dihydrate crystallites in crystallization process during reaction
    DOU Yan, LIU Tonghai, SHEN Hao, ZHENG Zhiyin, LIU Rong, CUI Peng
    2016, 67(6):  2449-2455.  doi:10.11949/j.issn.0438-1157.20151942
    Abstract ( 93 )   PDF (1117KB) ( 352 )  
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    In CaHPO4·2H2O-H2SO4-H3PO4-H2O system, an orthogonal experiment with five factors and four levels, including crystallization temperature, SO42- concentration and P2O5 concentration in liquid phase (solution), stirring rate and crystallization time was designed. Based on the measurement of average particle size, the optimized process parameters for the maximum mean particle size are, 80℃ of crystallization temperature, 50 g·L-1 of SO42- concentration, 260 g·L-1 of P2O5 concentration, 50 r·min-1 of stirring speed, and 2 h of crystallization time. Under the optimum conditions of the crystallization process, by means of analyses on the concentrations of SO42- and P2O5 in solution, and the techniques of XRD, SEM, EDS and laser particle size measurement, it showed that the reaction stage was the first 40 min with a decrease in mean particle size, and after 40 min, the procedure of crystallization follows the Ostwald grading rules, along with the evolution from CaSO4·0.5H2O to CaSO4·2H2O, but with almost identical particle size.

    Kinetic analysis of arsenate removal by Donnan dialysis
    ZHAO Bin, LIU Anqi, DIAO Falin, TAN Yun, ZHANG Zhaohui, WANG Liang
    2016, 67(6):  2456-2461.  doi:10.11949/j.issn.0438-1157.20151980
    Abstract ( 96 )   PDF (472KB) ( 232 )  
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    Donnan dialysis is a selective membrane process driven by an electrochemical potential. It can be used for arsenate [As(Ⅴ)] removal from drinking water. In this study, the effects of the intermembrane As(Ⅴ) mobility, membrane affinity to As(Ⅴ), membrane effective area and its thickness on As(Ⅴ) removal kinetics were investigated based on the analysis of the process variables in an As(Ⅴ) dialytic model. The results indicated that when the rotation rate was higher than 200 r·min-1, the intermembrane diffusion was the rate-limiting step for the As(Ⅴ) mass transfer in the Donnan dialysis process. Higher intermembrane mobility, larger membrane area and thinner membrane accelerated the As(Ⅴ) removal on the same degree. However, they did not change the residual As(Ⅴ) concentration in the feed solution at the Donnan equilibrium. The conditions of both feed and stripping solutions affected the As(Ⅴ) concentration gradient across the membrane. Besides the As(Ⅴ) flux, they also altered the Donnan equilibrium. Membrane module of the high packed density and in-situ As(Ⅴ) removal from stripping solution were proposed for the development of novel arsenic removal device based on Donnan dialysis.

    Identification of wastewater operational conditions based on manifold regularization semi-supervised learning
    ZHAO Lijie, WANG Hailong, CHEN Bin
    2016, 67(6):  2462-2468.  doi:10.11949/j.issn.0438-1157.20151625
    Abstract ( 87 )   PDF (933KB) ( 214 )  
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    The wastewater treatment process is vulnerable to the impact of external shocks to cause sludge floating, aging, poisoning, expansion and other failure conditions, resulting in effluent deterioration and high energy consumption. It is urgent to quickly and accurately identify the operating conditions of wastewater treatment process. In the existing supervised learning methods all the data are labeled which are time consuming and expensive. A multitude of unlabeled data to collect easily and cheaply have rich and useful information about the operating condition. To overcome the disadvantage of supervised learning algorithms that they cannot make use of unlabeled data, a semi-supervised extreme learning machine algorithm based on manifold regularization is adopted to monitor the operation states of biochemical wastewater treatment process. The graph Laplacian matrix is constructed from both the labeled patterns and the unlabeled patterns. Extreme learning machine algorithm is adopted to handle the semi-supervised learning task under the framework of the manifold regularization. It constructs the hidden layer using random feature mapping and solves the weights between the hidden layer and the output layer, which exhibit the computational efficiency and generalization performance of the random neural network. The results of simulation experiments show that the fault identification method based on semi supervised learning machine has superiority to the basic extreme learning machine in improving the accuracy and reliability.

    Ensemble soft sensor modeling for dynamic liquid level of oil well based on multi-source information feature fusion
    LI Xiangyu, GAO Xianwen, LI Kun, HOU Yanbin
    2016, 67(6):  2469-2479.  doi:10.11949/j.issn.0438-1157.20151673
    Abstract ( 125 )   PDF (22334KB) ( 170 )  
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    The dynamic liquid level (DLL) of an oil well is traditionally measured onsite by using the acoustic method. This method, however, has its limitation in determining real-time dynamic liquid level. A new ensemble soft-sensor approach of DLL based on the multi-source information feature fusion was proposed. The polish rod load and vibration signal in the time domain was transformed into the frequency domain using fast Fourier transform (FFT). The kernel principal component analysis (KPCA) was used to extract the nonlinear feature of the load and vibration spectral signal and the power, casing head pressure and tubing head pressure time signal. The improved fuzzy interactive self-organizing data analysis technique algorithm (ISODATA) and Gaussian process regression (GPR) were used to fuse time/frequency information feature and establish multiple sub-models. Then, the final DLL prediction model was obtained through the ensemble of the sub-models based on the weight factor calculated by optimized-weighted Dempster-Shafer (D-S) theory. The oil field application showed the validity of the proposed method.

    Multiple kernel least square support vector machine model for prediction of cement clinker lime content
    ZHAO Pengcheng, LIU Bin, GAO Wei, ZHAO Zhibiao, WANG Meiqi
    2016, 67(6):  2480-2487.  doi:10.11949/j.issn.0438-1157.20151598
    Abstract ( 118 )   PDF (572KB) ( 209 )  
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    Aiming at the problem of how to accurately predict the cement clinker fCaO content, the traditional single kernel least squares support vector machine (LSSVM) is difficult to show the complex non-linear relation between the clinker fCaO content and corresponding variables exactly. Thus, the multiple kernel least square support vector machine (MKLSSVM) containing three kernel function is presented based on multiple kernel learning to avoid the influence of the single kernel function on the model accuracy. As a result of artificial selection the parameters of MKLSSVM is blindness and uncertainty. The random perturbation chaos particle swarm optimization (RPCPSO) algorithm is presented to get the best parameters of MKLSSVM. The cement clinker fCaO content model is built by using the RPCPSO algorithm to optimize the parameters of MKLSSVM. Simulation results indicated that the RPCPSO algorithm had a fast convergence speed, and the model had high precision and strong ability of power generalization. Thus, the model was valuable for practical application.

    Improved model-free control algorithm for multivariate coupling time-delay system
    NIU Peifeng, LI Mengning, SUN Lipeng, MA Yunpeng, LIU Weiyan, LI Gang
    2016, 67(6):  2488-2494.  doi:10.11949/j.issn.0438-1157.20151611
    Abstract ( 75 )   PDF (584KB) ( 193 )  
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    The industrial production is the lifeline of the country's economic development, and the process control plays an important role in industrial production. Inevitably, the actual industrial process control systems are time-delay system. Besides, there are more than one controlled variable in most of the industrial production processes, and these controlled variables are coupled. All of these factors result in a huge difficulty to build an exact mathematical model for the control system, indicating that the tradition control methods cannot meet the control requirements nicely. With model-free adaptive control (MFAC) method, controller can be directly designed without exact model to reach the control objectives. Given the large time-delay of CFBB, the control law in MFAC is analyzed by changing the period of D-value,and control algorithm should be improved by increasing the period of D-value. Then, the decoupling control strategy of MIMO can be achieved. In the end, taking the circulating fluidized bed boiler combustion process as example, the MATLAB computer simulation results show that the algorithm has better control effect.

    Effect of surface tension on deformation of free falling drops
    DING Siyuan, WANG Ruixiang, XU Rongji, ZHANG Yihao, CAI Jichi
    2016, 67(6):  2495-2502.  doi:10.11949/j.issn.0438-1157.20151867
    Abstract ( 223 )   PDF (2067KB) ( 546 )  
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    The deformation of moving drop plays an important role in its evaporation and combustion. Surface tension is one of the factors which influence the deformation. For investigating the effect of surface tension on the deformation, the low concentration SDBS surfactant water based solutions with surface tension in the range of 30 to 72 mN·m-1 are used as the experimental liquid. The different sizes of needles are employed to get drops with diameter at 3-5 mm. The image processing is utilized to analyze the drop shape by using a high speed camera (Phantom V211, 1000 pps,800×600 pixel). The complete drop falling image process is assembled by 9 sections at different position with different drops. A stable drop formation time of (2.4±0.1) s makes the dispersion of size and initial velocity of these drops meet the experimental accuracy. Analyzing the experimental data by Image-pro plus obtains the semi-empirical correlations of Eötvös number (Eo). The results show that the period and amplitude of drop deformation decrease with increasing surface tension. Furthermore, the momentum transfer inside the drop causes initial transient impulse, which makes the drop periodic deformation when it falls down.

    Synergistically enhanced thermostability of Saccharomyces cerevisiaeby ubiquitin-like protein mediation and heat shock response
    XIAO Bing, LI Jun, LI Chun
    2016, 67(6):  2503-2509.  doi:10.11949/j.issn.0438-1157.20151778
    Abstract ( 51 )   PDF (1094KB) ( 161 )  
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    To improve the thermostability and fermentation performance of Saccharomyces cerevisiae to reduce the energy consumption of the cooling progress in industrial fermentation, the protein homeostasis was regulated through ubiquitin-like protein mediation and heat shock response. In this study, many heat-resistant gene devices were mined out from genes related to protein homeostasis and constructed with the regulatory device FBA1p, and then transformed into Saccharomyces cerevisiae INVSC1. Outstanding heat-resistant devices FBA1p-atg8 and FBA1p-hsp104 were screened through gradually increased temperature incubation. Compared with the control, the OD660 of the engineered yeast strains S.c-ATG8 and S.c-HSP104 were both over 50% higher (84 h) and their cell viability were 1.64 to 3.01 times higher (72 h) when cultured at 40℃. The physiological characteristics implied that the thermotolerant strains possessed better cell wall integrity and higher trehalose content. In order to strengthening the regulatory mechanisms of both ubiquitin-proteasome system pathway and heat-shock responses within the network of protein homeostasis, atg8 and hsp104 were assembled to construct bifunctional engineered strain S.c-ATG8-HSP104, which showed better growth ability, stronger cell activity and higher ethanol yield at 40℃. The results revealed that the synergistic effect of ubiquitin-like protein and heat shock protein could enhance yeast thermotolerance and improve strain activity.

    Improvement of uracil auxotrophic transformation system in Trichoderma reesei QM9414 and overexpression of β-glucosidase
    ZHONG Lixia, QIAN Yuanchao, DAI Meixue, ZHONG Yaohua
    2016, 67(6):  2510-2518.  doi:10.11949/j.issn.0438-1157.20151654
    Abstract ( 115 )   PDF (1537KB) ( 536 )  
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    Trichoderma reesei is an industrial filamentous fungus widely used for cellulase production. However, the difficulty in genetic modification of the high-production mutants limits the strain improvement. Firstly, the pyr4 gene was successfully deleted by target integration strategy in T. reesei QM9414 to construct a uracil auxotroph strain QP4. Compared with those in the parental strain, not only the genetic transformation efficiency was improved, but also the cellulase production was not influenced in QP4. The β-glucosidase (BGL) encoding gene bgl1 was further overexpressed in the QP4 strain. The transformants QPB4 and QPB5 with increased BGL activity were obtained by rapid screening based on the esculin plate. The BGL activities in the culture supernatants of QPB4 and QPB5 exhibited 10.01- and 8.26- fold higher than that in QP4, respectively. The crude enzyme preparations were used to saccharify two types of differently pretreated corncob residues. The glucose yields from saccharification of acid-pretreated corncob by QPB4 and QPB5 were 60.98% and 52.44% higher than that by QP4, respectively, while using the delignined corncob as substrate, the glucose yields by QPB4 and QPB5 were improved 80.01% and 86.00%, respectively. These results suggested that improvement of the genetic manipulation system in T. reesei greatly facilitated the strain improvement and increased the saccharification efficiency.

    Quantitative analysis of typical anhydro-sugars obtained during pyrolysis of cellulose based on benzoylation
    WANG Yang, GONG Xun, LENG Erwei, ZHANG Biao, HE Jianqing, XU Minghou
    2016, 67(6):  2519-2524.  doi:10.11949/j.issn.0438-1157.20160030
    Abstract ( 92 )   PDF (533KB) ( 163 )  
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    A derivation method based on bezoylation was applied to quantitative analysis of three typical anhydro-sugars obtained from pyrolysis of cellulose on a fixed bed reactor. The experimental results showed that this precolumn HPLC derivatization was proved to be an efficient and accurate method for the rapid determination of anhydro-sugars. Cellobiosan and cellotriosan may be produced via thermal cleavage of glycosidic bonds during cellulose pyrolysis rather than secondary polymerization of the levoglucosan. The higher DPs anhydro-sugars had less thermal stability and they were more susceptible to decomposition at the higher temperature.

    Achievement of long-term and stable partial nitritation in sequencing batch reactor
    ZHAO Mengyue, PENG Yongzhen, WANG Bo, GUO Yuanyuan
    2016, 67(6):  2525-2532.  doi:10.11949/j.issn.0438-1157.20151877
    Abstract ( 74 )   PDF (849KB) ( 184 )  
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    In this study, a sequencing batch reactor (SBR) was used to treat domestic wastewater, and the optimal aeration rate and time to realize partial nitritation (PN,NH4+-N was partially converted to NO2--N) were obtained through three preliminary tests. A long-term PNSBR was operated more than 110 d (450 cycles) with an optimal aeration rate [7.2-12 L·(h·L)-1] and time (2-3 h) during aeration. The results showed that the nitrite accumulation rate in the effluent maintained 94%-100%, indicating the stable partial nitrification. The ratios between NO2--N and NH4+-N were in the range of 2-4. Further analysis demonstrated that in the long-term operation of PNSBR, the low dissolved oxygen (DO) by controlling aeration benefited the ammonia oxidizing bacteria (AOB) activity but inhibited the nitrite oxidizing bacteria (NOB) one. On the other hand, the residual nitrite after decanting in a cycle was removed via denitrification (endogenous in this cycle and exogenous in next cycle) by using organics in raw wastewater, through which substrates for NOB were prohibited, and thus stable PN was realized. The process of simultaneous anammox and denitrification (SAD) was widespread, and PNSBR, as a pre-treatment reactor, can provide substrates for SAD, and thus PN was a potential technology in future.

    Shortcut nitrification-denitrification and population dynamics of nitrifying bacteria in MUCT process treating domestic wastewater
    ZENG Wei, ZHANG Jie, JI Zhaohua, WANG Anqi, PENG Yongzhen
    2016, 67(6):  2533-2541.  doi:10.11949/j.issn.0438-1157.20151853
    Abstract ( 98 )   PDF (878KB) ( 142 )  
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    Shortcut nitrification-denitrification and population dynamics of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were investigated in a continuous flow MUCT reactor treating real domestic wastewater. Shortcut nitrification-denitrification was achieved by controlling low dissolved oxygen (DO) concentration of 0.5 mg·L-1 and short hydraulic retention time (HRT) of 6 h. Nitrite accumulation ratios reached above 90%. TN removal in the phase of shortcut nitrification-denitrification was up to 90%, far higher than complete nitrification with 74% of TN removal. The results of quantitative real time PCR (QPCR) indicated that during complete nitrification-denitrification AOB abundance exhibited a decline tendency, decreasing from 1.69×109 cells·(g dried sludge)-1 to 3.76×107 cells·(g dried sludge)-1, and NOB abundance maintained at 108 cells·(g dried sludge)-1. During shortcut nitrification-denitrification, the abundance of AOB slightly increased from 3.17×106 cells·(g dried sludge)-1 to 1.32×107 cells·(g dried sludge)-1 accompanied with a slight increase of ratio of AOB to total bacteria. The abundance of NOB fluctuated in a range of 5.9×107-1.78×108 cells·(g dried sludge)-1. The ratio of NOB to total bacteria dropped from 1.44% to 0.47%. Therefore, the abundance decrease and bioactivities inhibition of NOB were the important factors to achieve shortcut nitrification-denitrification in MUCT process treating real domestic wastewater. During shortcut nitrification-denitrification due to low DO concentration and short HRT, AOB abundance and their relative distribution did not increase, even descended. But that did not influence the removal of ammonia and total nitrogen.

    Effect of temperature, contact pressure and duration on solid-bridge force of coal ash
    ZHAO Shuo, LUAN Chao, YOU Changfu
    2016, 67(6):  2542-2547.  doi:10.11949/j.issn.0438-1157.20160096
    Abstract ( 61 )   PDF (559KB) ( 103 )  
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    During the combustion process of coal, biomass or other solid fuels, the phenomenon of ash deposition is a common but serious problem is that it can seriously affect the safe and stable operation and performance of the equipment. During the ash deposition process, the adhesive behavior between different ash particles plays an important role. Solid and liquid bridge forces are two important type of adhesive force. But the studies of solid- bridge force are not enough now. An experimental system for the measurement of solid-bridge force of ash at high temperatures was designed and developed. The maximum temperature of the system was 1600℃. By using this experimental system the solid-bridge force can be measured and the effect of different temperatures, contact pressure and duration can be researched. The result indicated that the temperature dependence of the neck tensile strength development showed a bimodal distribution. It was because that the phase conditions of ash were changed by increasing temperature, resulting in the change of the content of the glassy substance. The molecular diffusion rate at the interface of the ash column was accelerated with increasing temperature. And it also accelerated the improvement of the void and the lattice defect in the neck. By increasing the contact duration, the neck tensile strength increased because the process of the improvement of the void and the lattice defect in the neck became more fully. If the duration was enough, the neck tensile strength would reach a steady state. The neck tensile strength was increased with increasing contact pressure. The high pressure made the contact between the two interface of the ash column more closely and it was conducive to accelerate the molecular diffusion rate. High temperature and contact pressure could make the neck tensile strength reach a steady state in a shorter duration. The work provided a basis to establish the model of solid-bridge force of coal ash and predict the behavior of coal ash deposition in the specific conditions.

    Effects of coal molecular structure on adsorption and diffusion behaviors of coalbed methane
    WANG Baojun, ZHANG Lina, LING Lixia, ZHANG Riguang
    2016, 67(6):  2548-2557.  doi:10.11949/j.issn.0438-1157.20151780
    Abstract ( 170 )   PDF (1240KB) ( 330 )  
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    The effects of microcrystal structures, such as the extension of basic structural unit (La) and the number of basic structural unit (N), as well as the surface structures including different types of defects and oxygen-containing functional groups, on the adsorption and diffusion of coalbed methane were investigated. The adsorption amounts were simulated by using the Monte Carlo (MC) method, and the diffusion coefficients of coalbed methane were simulated by using molecular dynamics (MD) simulation. All of the simulations were conducted in the condition of 303 K and 10 MPa. It can be concluded that the adsorption capacity of methane on unit mass of coal decreases with N increasing, as well as the existence of defects and oxygen-containing functional groups. The diffusion coefficient of methane increased with La extending and shows a complex process influenced by increasing N. The existence of single-defect and C O was favorable of diffusion of coalbed methane. The coalbed methane was easy to diffuse in larger pore of coal. Finally, the micro model of coalbed methane diffusion for the coal particles of radial heterogeneous was proposed base on the micro-influenced factors and macro performance of the migration of coalbed methane.

    Effect of temperature and AAEM species on fast pyrolysis of biomass tar
    FENG Dongdong, ZHAO Yijun, TANG Wenbo, ZHANG Yu, QIAN Juan, SUN Shaozeng
    2016, 67(6):  2558-2567.  doi:10.11949/j.issn.0438-1157.20151907
    Abstract ( 94 )   PDF (776KB) ( 236 )  
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    Pyrolysis temperature, heating rate, alkali metal and alkaline earth metal (AAEM) species have significant effects on biomass pyrolysis. In this paper, by using the pyrolysis gas chromatography mass spectrometry (Py-GC/MS), the effect of temperature and AAEM species on fast pyrolysis of the biomass tar was investigated. The influence of pyrolysis temperature and AAEM species on the pyrolysis characteristics of biomass (rice husk and sawdust, H-form rice husk and H-form sawdust) was analyzed by means of mass loss of samples. The online semi quantitative analysis of pyrolysis tar was carried out by gas chromatography mass spectrometry (GC/MS). The distribution of molecular weight of pyrolysis tar was discussed. The results showed that during fast pyrolysis of biomass, the removal of AAEM species reduced the mass loss rate. With increasing pyrolysis temperature in the range of 500-900℃, the tar composition of high molecular weight decreased gradually. The polymerization of the tar precursor was limited by the AAEM species and the formation of the heterocyclic carbon ring was further inhibited. The molecular weight of tar of rice husk pyrolysis was mainly distributed in the range of 110-129. The tar yield of sawdust fast pyrolysis was higher than that of rice husk. The molecular weight distribution of sawdust tar was wide, containing more substances with high molecular weight (150-209).

    Removal of ammonia by absorption combined with electrochemical oxidation on RuO2/Ti anode
    XU Xiaohua, XU Qingzhi, HUANG Guifeng, WANG Lili, HUANG Liwei
    2016, 67(6):  2568-2574.  doi:10.11949/j.issn.0438-1157.20151659
    Abstract ( 106 )   PDF (528KB) ( 349 )  
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    Ammonia in the exhaust gas was treated by solution absorption combined with electrochemical oxidation. The electrochemical reactor was a tubular glass reactor (φ35 mm×350 mm) with a stainless steel mesh attached to the inner wall as the cathode, and a titanium rod (φ10 mm×350 mm) coated with RuO2 (RuO2/Ti) fixed on the axis of the reactor as the anode. Electrodes were immersed in absorption solutions. The sample gas containing ammonia was introduced to the reactor by a gas distributor installed at the bottom of the reactor. Experimental results indicated that the removal of ammonia was higher by absorption combined with electrochemical oxidation compared with solution absorption only. The removal of ammonia is higher in NaCl solution than that in Na2SO4 one, which was attributed to the indirect oxidation of active chlorine generated by electrochemical reaction on RuO2/Ti anode. It was confirmed that oxidation of ammonia increased with low pH of NaCl solutions. With the increase of current density applied to the reactor, the decomposition of ammonia also increased. The major of absorbed ammonia in NaCl and Na2SO4 solution converted to nitrogen after electrochemical reaction. Only a small amount of nitrate was found in solutions after reaction.

    Influence of SRT on enriching halophilic MMC with capacity of PHA storage
    CUI Youwei, LIN Xiaoyuan, JI Siyuan, SHI Yunpeng
    2016, 67(6):  2575-2582.  doi:10.11949/j.issn.0438-1157.20151644
    Abstract ( 102 )   PDF (662KB) ( 129 )  
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    Enriching mixed microbial culture (MMC) with capacity of PHA storage via controlling the enrichment process parameters is the first and the most important step for the fermentation production of PHA. This paper elucidated the role of sludge retention time (SRT) in the enrichment process under batch culture conditions. The results showed that SRT influenced the specific substrate degradation rate (qS), specific PHA accumulation rate (qP) and the PHA storage capacity of enriched MMC. The long SRT (SRT 4 d) led to the decreased qS, qP and PHA accumulation ability. The short SRT reduced the PHA conversion rate (YPHA/S) and PHA accumulation ability of MMC. The optimal SRT was determined as 2 d for enriched MMC in this study, which presented 56% cell dry weight PHA content. The study proved that the SRT played the important role in enriching halophilic MMC, which laid the foundation on enriching PHA-storage MMC rapidly.

    Exergy method used in selection of waste gasification agents
    DONG Shaofeng, YUAN Haoran, WANG Yazhuo, LU Tao, CHEN Yong
    2016, 67(6):  2583-2590.  doi:10.11949/j.issn.0438-1157.20151600
    Abstract ( 97 )   PDF (651KB) ( 323 )  
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    As to the conversion efficiency of waste gasification, cold gas efficiency (CGE) has been traditionally used. In this paper the exergy method was adopted, and exergy efficiency and cumulative exergy consumption (CExC) efficiency were put forward. CGE, exergy efficiency and CExC efficiency were compared among three agents for waste gasification. It was found that the best agent was different according to different efficiencies. The exergy method was more comprehensive and had more practical value than traditional method. The exergy efficiency and CExC efficiency emphasized the utilization potential of enthalpy exergy carried by syngas. As the CExC efficiency took the energy cost of acquiring agents into consideration, it can provide proof for the scientific selection of agents.

    Sub-culturing of novel Blautia coccoides GA-1 and acetate synthesis from H2/CO2 in subcultures
    LIU Chong, LI Jianzheng, ZHANG Yafei, ZHANG Yupeng, YOU Lijian, LIU Dongmei
    2016, 67(6):  2591-2597.  doi:10.11949/j.issn.0438-1157.20151884
    Abstract ( 166 )   PDF (538KB) ( 378 )  
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    Though homoacetogens have been defined as autotrophic anaerobes using acetyl-CoA Wood-Ljungdahl carbon fixation pathway (WLP) for energy conservation, acetate production and biomass formation from CO2, these anaerobes can also utilize organic compounds heterotrophically to produce acetate and form biomass by Embden-Meyerhof-Parnas (EMP) glycolysis. A better understanding of the interrelationship between autotrophy and heterotrophy in homoacetogens will be helpful for acetate biosynthesis from exhaust rich in CO2. However, interaction of the two metabolisms has not been well understood though both of which have been extensively investigated respectively. Blautia coccoides GA-1, a novel homoacetogen strain obtained in a previous study, was introduced to the present research and the interrelationship between autotrophy and heterotrophy in the strain was investigated by sub-culturing with glucose and (or) H2/CO2 (vol, 4:1) as carbon source (s). The results showed that the cell production of strain GA-1 in H2/CO2 cultures was too low to be sub-cultured after the 5th generation due to the energy produced was very limited in WLP. On the contrary, the strain could grow very well in glucose cultures and could be sub-cultured steadily. However, the autotrophic capability of the subcultures decreased by generations, even lost since the 7th generation in 1000 mg·L-1 glucose cultures. This may be resulted in: (1) the competition for Coenzyme A (CoA) between the autotrophic WLP and the heterotrophic EMP glycolysis, (2) ATP produced in the strain used up for biosynthesis rather for acetate synthesis from H2/CO2, (3) inhibition of lower pH less than 5.5 to the activity of hydrogenase, (4) negative effect of the lower pH on intracellular balance of NADH/NAD+. In mixotrophic cultures with H2/CO2 and 200 mg·L-1 glucose as co-carbon sources, strain GA-1 could not only be sub-cultured steadily but also keep autotrophic activity well in the generations with a specific acetate production of about 2.16 g·(g dry cell)-1 from H2/CO2.

    Hg2+ removal from FGD system by thiol polystyrene resin
    FU Kangli, YAO Mingyu, QIN Chuanguang, CHENG Guangwen, NIE Jianping
    2016, 67(6):  2598-2604.  doi:10.11949/j.issn.0438-1157.20151675
    Abstract ( 151 )   PDF (714KB) ( 405 )  
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    Thiol polystyrene resin was prepared by two-step reaction with chloromethyl polystyrene resin as material, and then it was characterized by Fourier transform infrared spectroscopy, Brunauer-Emmett-teller, elemental and thermogravimetric analyses. The Hg2+ removal performance of thiol polystyrene resin was also investigated in simulated flue gas containing Hg2+, desulfurization effluent and desulfurization slurry. It was found that thiol polystyrene resin possessed high thermal stability and could be used as an absorbent for Hg2+ removal from flue gas, desulfurization effluent and desulfurization slurry. The thiol polystyrene resin showed Hg2+ removal efficiencies above 90%, 100% and 100% in flue gas, desulfurization effluent and desulfurization slurry, respectively. The placation of thiol polystyrene resin in the wet flue gas desulfurization system could capture Hg2+ in this system and avoid its entering to desulfurization gypsum, which could bring the mercury reemission. Moreover, thiol polystyrene resin captured Hg2+ was regenerated successfully by 6 mol·L-1 HCl and its regeneration rate with three times regeneration reached up 90.2%.

    Isolation of hemicelluloses from acacia wood with hydrothermal prehydrolysis and its characterization of structure and component
    ZHU Ning, SHI Haiqiang, CAO Nan, XIONG Xuedong, NIU Meihong, PING Qingwei
    2016, 67(6):  2605-2611.  doi:10.11949/j.issn.0438-1157.20151842
    Abstract ( 137 )   PDF (790KB) ( 303 )  
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    Hydrothermal prehydrolysis of acacia wood was conducted at various conditions and the hemicelluloses dissolved in prehydrolysate was recovered by ethanol precipitation. Conditions test design was used to optimize the pre-hydrolysis conditions for the maximum hemicelluloses recovery rate as solid phase. Then, the composition, thermal stability and structural characterization were analyzed on the recovered hemicelluloses. The optimum pre-hydrolysis temperature and time were determined to be 170℃ and 20 min, respectively. Recovery rate of 3.93% against carbohydrate content of wood chip was obtained under the optimum conditions and main composition was xylose, accounting for 75.56% in mass, and 10.71% of glucose and 7.80% of galactose were also found. The recovered hemicelluloses at 160℃/40 min, 170℃/15 min,170℃/25 min and 180℃/15 min showed a same composition with the result of 170℃/20 min but a little bit difference in the content by the analysis of ion chromatography. The thermo gravimetric analysis indicated that thermal stability of recovered hemicelluloses decreased along with the improvement of prehydrolysis temperature and extension of prehydrolysis time. Linkage of acetyl group, arabinose and galactose was found on the xylan chain by the analysis of nuclear magnetic resonance and Fourier transform infrared spectroscopy.

    Crystallization properties of non-Newtonian synthetic coal slag
    XUAN Weiwei, ZHANG Jiansheng, XIA Dehong
    2016, 67(6):  2612-2617.  doi:10.11949/j.issn.0438-1157.20151430
    Abstract ( 116 )   PDF (3076KB) ( 244 )  
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    In entrained flow gasifiers, crystallization inside the slag can increase the viscosity of the slag, changing the flow from Newtonian to non-Newtonian. In order to get an understanding of the crystallization characteristics of the slag, the single hot thermocouple technique(SHTT) and a high-temperature quenching furnace were set up to study the crystallization process. The crystals morphology under different temperatures and cooling rates were recorded and the temperature-time-transformation (TTT) diagram was obtained which can illustrate the influence of temperature. The decrease of temperature can increase the driving force and reduce the required time for crystallization. But further decrease of temperature would increase the viscosity which limited the movement of ions. The slag was quenched at different temperatures and it is found that the crystalline phases changed at different temperatures. Diopside is the main crystal at high temperature with some anorthite at low temperature. The high cooling rate can reduce the size of the crystals but has little effect on the crystalline types.

    Oxidation of lignin-degradation products by heat-activated persulfate
    RONG Yayun, SHI Linli, ZHANG Chen, ZOU Lihua, XU Ying, ZHU Junjun, CHEN Liwei, XU Yong, YONG Qiang, YU Shiyuan
    2016, 67(6):  2618-2624.  doi:10.11949/j.issn.0438-1157.20151816
    Abstract ( 190 )   PDF (593KB) ( 231 )  
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    Aiming at the effect of lignin-degradation products on ethanol fermentation during the bioethanol production process, six kinds of typical lignin-degradation products (vanillin, syringaldehyde, 4-hydroxybenzaldehyde, vanillic acid, syringic acid and 4-hydroxybenzoic acid) were selected to oxidative removal by a new detoxification technology-advanced oxidation process of heat-activated persulfate. The oxidation removal conditions and its oxidation mechanism were also investigated. The results indicated that the optimal oxidation conditions were pH 6.0, 80℃, and the persulfate concentration of 1.5 g·L-1 based on 0.1 g·L-1 vanillin. On the basis of the optimized conditions, the oxidation effect of other five of typical lignin-degradation products was studied. The results showed that the effects of oxidation removal were obvious. The removal ratio of vanillin, 4-hydroxybenzaldehyde, vanillic acid and syringic acid reached to 100% within 1 h, while that of syringaldehyde reached to 100% within 2 h. The study of oxidative mechanism was to indirectly decide which the main active species was in the reaction process by the addition of radical scavengers of methanol and t-butanol. The results showed that the main active species were sulfate radicals. Therefore, using heat-activated persulfate is a good way for oxidative removal of the lignin-degradation products.

    O2 generation path in Fe2+/H2O2 system
    ZHAO Haiqian, GAO Xingcun, WANG Zhonghua, GAO Jihui
    2016, 67(6):  2625-2630.  doi:10.11949/j.issn.0438-1157.20151820
    Abstract ( 75 )   PDF (598KB) ( 168 )  
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    It is important to understand the O2 generation path in Fe2+/H2O2 system to avoid invalid decomposition of H2O2 and to reduce the cost of pollutants degradation technology using Fe2+/H2O2 system. In this paper, radical scavengers were adopted to investigate the roles of different radicals on the generation of O2 in Fe2+/H2O2 system. The results showed that there were few O2-· in Fe2+/H2O2 system, and O2-· was not the main reagent to generate O2. After ·OH was captured, the generation rate of HO2· was still high, however, there was no O2 generation. This indicated that ·OH and HO2· took part in the reaction to generate O2 directly. ·OH+HO2·-H2O O2 is the main reaction path to generate ;O2. Controling H2O2 decomposition path towards ·OH and restraining the production of HO2· were the effective ways to increase the utilization rate of H2O2.

    Effects of supercritical CO2 treatment on structures and properties of cassava starch
    BAI Jun, LI Xidu, XIE Xinling, ZHANG Youquan
    2016, 67(6):  2631-2637.  doi:10.11949/j.issn.0438-1157.20151752
    Abstract ( 79 )   PDF (4627KB) ( 210 )  
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    Cassava starch was extracted in different conditions with supercritical carbon dioxide. The morphological characteristics and the gelating properties of the treated starch, such as particle morphology, swelling degree, crystalline structure, viscosity, retrogradation and freeze-thaw stability, were evaluated and compared with native cassava starch by using scanning electron microscope, X-ray diffraction analyzer, Brabender visco-analyser or other methods. As a result, it showed that with the change of the pressure, temperature and time of the treatment, the morphology of the treated starch was not obviously changed, but the swelling degree decreased and the crystallinity increased. It also found that the anti-precipitability of the treated starch gel was strengthened and the freeze-thaw stability reduced. Meanwhile, Brabender viscosity analysis suggested that the gelation temperature of the treated starch could be slightly raised and the peak viscosity of the treated starch gel decreased, while the thermal stability little changed. All the results indicated that the cassava starch molecules could be partially degraded and the ratio of amylose to amylopectin would increase in the process of supercritical treatment, leading to the alteration of some microstructure characteristics and gelating properties of cassava starch.

    Preparation of biomass-based activated carbon with high-mesoporosity by direct zinc chloride activation
    XING Xianjun, SUN Zongkang, FAN Fangyu, MA Peiyong, ZHANG Xianwen, YU Jin, WU Zhaobin
    2016, 67(6):  2638-2644.  doi:10.11949/j.issn.0438-1157.20151148
    Abstract ( 123 )   PDF (2872KB) ( 233 )  
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    The high-mesoporosity activated carbon was prepared from sawdust by zinc chloride activation. Before activation, the zinc chloride and sawdust were mixed directly without binder or water. In order to investigate the feasibility of this process, the effects of factors such as impregnation ratio, activation temperature, activation time and the density on methylene blue adsorption properties of the activated carbon were studied. The results showed that the optimum conditions were impregnation ratio 1.0:1, activation temperature 950℃, activation time 60 min and the density 1.4 g·cm-3. The activated carbon prepared under the optimized conditions had a methylene blue adsorption value of 387 mg·g-1, a BET surface area of 2104 m2·g-1 and the average pore diameter of 3.11 nm. The total pore volume of the activated carbon was 1.63 cm3·g-1 with a mesopore volume of 1.17 cm3·g-1, yielding a high mesopore percentage of 71.8%. The results showed that the activated carbon had an excellent adsorption capacity due to its large surface area and well-developed mesopore structure, indicating the feasibility of the dry process.