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Table of Content
05 April 2008, Volume 27 Issue 4
    进展与述评
    Present status and prospect of carbon foams
    XIAO Zhenghao,ZHOU Ying,XIAO Nan,QIU Jieshan
    2008, 27(4):  473. 
    Abstract ( 1602 )  
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    Carbon foam,a new type of carbon materials,has drawn much attention across the world. The structures and properties of carbon foams vary greatly in terms of the raw materials used and the preparation methods adopted. In general,organic polymers,mesophase pitch,coal and coal-related materials can be used as the starting materials for the production of carbon foams. This paper reviews the structure,property and new progresses of carbon foams as well as their potential applications and prospect,where the spectacular features of making carbon foams from coal and coal-related precursors are highlighted.
    Fabrication and application of magnetic nano-wire arrays
    SU Wu,HUANG Ying,YAN Li
    2008, 27(4):  478. 
    Abstract ( 1570 )  
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    This paper reviews recent developments of the fabrication methods of magnetic nano-wire arrays by depositing into pores of membranes,such as the sol-gel method,chemical deposition method and electrochemical deposition method. These membranes include porous anodic aluminum (AAO) template and track-etched polymer membrane. The applications of nano-wire arrays to magnetic recording,giant magneto resistance,quantum disk and super-hgh density magnetic recording are presented.
    Research progress of spinel-cobalt blue pigment
    LIU Zhubo,YE Mingquan,HAN Aijun
    2008, 27(4):  483. 
    Abstract ( 1690 )  
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    In this paper the structure and coloration mechanism of spinel cobalt blue pigments are introduced. Recent research progress of synthesis methods and technologies of cobalt blue pigment are summarized,in terms of the preparation methods of nano-materials. These processes include solid phase reaction process,liquid phase reaction process and gas phase process. The solid phase reaction process is commonly used in industry because of its simple technology,but the particle size,color,stability of pigment can not fully meet the market demand. High quality cobalt blue pigments can be prepared by the liquid phase reaction process or gas phase process,but both processes are complex and expensive. The research directions and application prospects of cobalt blue pigments are also presented.
    Recent progress of technology and application of heat transfer enhancement of nanofuilds
    LIN Jing,FANG Liguo
    2008, 27(4):  488. 
    Abstract ( 2054 )  
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    This paper summarizes the recent research process of the preparation,thermal conductivity, convective and boiling heat transfer of nanofluids and also introduces the application of nanofluids to microchannel heat exchangers. Moreover,the prospect of the technology and application of nanofluids is presented.
    Effect of easily degradable organic matter on the biodegradation of refractory organic pollutants
    WU Yaoguo,TAN Ying,HU Sihai,CHEN Peirong,LIU Baochao
    2008, 27(4):  495. 
    Abstract ( 2916 )  
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    The advances in the researches on impact of easily degradable organic matter on refracfory organic pollutants biodegradation around the world are reviewed in terms of growth metabolism,cometabolism and changing the bioavailability of the refractory organic pollutants through reaction with easily degradable organic matter. In light of the knowledge of microbiology and bioavailability of refractory organic pollutants,research topics to be done are proposed.
    Advances in preparation of nano-catalyst by micro-emulsification
    LI Zhaohui,DAI Wei,FU JiQuan
    2008, 27(4):  499. 
    Abstract ( 2473 )  
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    Microemulsification has been used as a new method for preparing nano-catalysts. In this paper,the principles,methods,affecting factors and separation method of preparing nano-catalyst by microemulsification are introduced and its application is reviewed. The development and innovation of this process are summarized.
    Progress of catalytic conversion of methane to syngas in the presence of oxygen
    JING Qiangshan,FANG Linxia,LOU Hui,ZHENG Xiaoming
    2008, 27(4):  503. 
    Abstract ( 1796 )  
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    In this paper,the research progress of synthesis gas preparation by catalytic conversion of methane in the presence of oxygen is summarized. The authors’ work in preparing syngas form methane in the presence of oxygen is introduced. Catalytic partial oxidation (CPO),autothermal CO2 reforming (ATR-CO2),autothermal H2O reforming (ATR-H2O) and triple-reforming of methane are reviewed. The achievements in catalyst,reaction mechanism and process conditions are also discussed. The research focus and commercial application of catalytic conversion of methane in the future are also prospected.
    Progress of catalysts for producing biodiesel by esterification and transesterification reaction
    HUANG Shifeng,CHEN Guo,FANG Baishan
    2008, 27(4):  508. 
    Abstract ( 1751 )  
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    Esterification and transesterification are the most common methods of producing biodiesel. It is important to select an appropriate catalyst based on the properties of raw oil. In this paper the alternative catalysts used in biodiesel production,such as acid catalyst,alkali catalyst,lipase catalyst,ionic liquid and non-catalytic process are reviewed. The advantages and disadvantages of different catalysts are compared according to catalysis mechanism,and the prospect of future development in this field is presented.
    Research progress of microemulsion polymerization in preparation of separation membranes
    SHEN Jiangnan,QIU Junhong,ZHENG Xingcun,WU Liguang,GAO Congjie
    2008, 27(4):  515. 
    Abstract ( 1993 )  
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    Microemulsion and microemulsion polymerization are introduced and the application of microemulsion polymerization to the preparation of olefin/paraffin and liquids separation membranes is reviewed. The existing problems of microemulsion polymerization in separation membrane preparation are discussed,and the future research and development are presented.
    Progress of medical dressing based on chitin/chitosan
    ZHANG Buning,CUI Yingde,CHEN Xunjun,YIN Guoqiang,LI Xinming,JIA Zhenyu
    2008, 27(4):  520. 
    Abstract ( 1801 )  
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    Natural polymer chitin and chitosan exhibit a variety of physicochemical and biological properties including biocompatibility,biodegradability,nontoxicity. Their hemostatic,antimicrobial,wound healing and tissue regeneration effects make them a very attractive substance for wound dressing. This paper reviews current research of medical dressing based on chitin/chitosan.
    研究开发
    Cloning and expression of 1,3-propenediol oxidoreductase isoenzyme gene yqhd from Escherichia coli
    LI Hongmei,CHEN Jia,LI Lin,XU Fei
    2008, 27(4):  527. 
    Abstract ( 1900 )  
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    1,3-propenediol oxidoreductase isoenzyme is one of the key enzymes in biotransformation systhesis of 1,3-propenediol,and is encoded by the yqhD gene. YqhD gene was amplified from E. coli by polymerase chain reaction (PCR). The fragment was inserted into plasmid pET28 cut by two restriction enzymes BamHI and NheI. The yqhD gene after recombinant and transformation was induced and expressed by IPTG in E. coli at 25 ℃ for 12 h. The expression product was checked by SDS-PAGE. The cloned yqhD gene was obtained and protein expression was realized. The catalytic activity of 1,3-propenediol oxidoreductase isoenzyme was improved by 88 fold. The yield of 1,3-propenediol in whole cell fermentation with recombined strain could reach 65%,higher than wild strain (yield 9.5%).

    Isolation of a bacteria strain degrading crude oil and its degradation characteristics

    PENG Gewei,YAN Guangxu,LIU Xiaochun,GUO Shaohui
    2008, 27(4):  531. 
    Abstract ( 1656 )  
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    A bacterial strain,designated as X3,which had the capability to degrade crude oil,was isolated from crude oil-polluted soil in the Dagang oil-field. The ability of strain X3 in the biodegradation of crude oil was studied,and the effects of different crude oil concentrations on the biodegradation of oil and the growth of bacteria were compared . The influence of different pH values and the concentration of NaCl on the biodegradation of crude oil were also investigated. The results showed that strain X3 was resistant to alkali and salt. The concentration of crude oil had a significant influence on the degradation rate of total petroleum hydrocarbons (TPH). When pH was 7 and the concentration of NaCl was 5g/L,X3 degraded approx. 72.6% of crude oil at 30℃ for 7 days. GC analysis showed that carbon number was the greatest factor that influenced the biodegradation. Degradation became more difficult with increasing carbon number of hydrocarbon.
    Retention of NAD(H) in non-charged ultra-fitration membrane reactor
    CHEN Hongwen,FANG Baishan,HU Zongding
    2008, 27(4):  535. 
    Abstract ( 1714 )  
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    Retention of NAD (H) was investigated in a self-built non-charged ultra-filtration membrane reactor. NAD (H) was retained effectively by ultra-filtration membrane in the presence of 50kDa polyethyleneimine (PEI). High retention ratio (R=0.823) was obtained with PEI/ NAD+ molar ratio 5:1 in Tris-HCl buffer. The increase of solution ionic strength caused a decrease of coenzyme retention but an increase of the permeation flux. The addition of 0.5% or 1% bovine serum albumin enhanced the coenzyme retention,minimizing the effect of ionic strength. The retention ratio of NADH was higher than that of NAD+ in PEI system. The influence of PEI on the activities of glycerol dehydrogenase and 1,3-propanediol oxidoreductase was also studied.
    Effect of non-ionic surfactants in bacteria leaching of chalcopyrite at low temperature
    ZHANG Decheng,ZHU Li,LUO Xuegang
    2008, 27(4):  540. 
    Abstract ( 1966 )  
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    To enhance the efficiency of bioleaching of chalcopyrite by using Acidithiobacillus ferrooxidans at a low temperature (8~10℃),the catalytic effects of non-ionic surfactants were investigated. The effects of the surfactants on bioleaching of chalcopyrite were evaluated by measuring the leaching rate of copper and the density of bacteria cells in solution. The results showed that the surfactants had promoting functions on the bioleaching process at a low temperature and TW-20 was the most effective surfactant. The optimum concentration of TW-20 was 0.01%. The final bioleaching rate was 49.87% for 90 days.
    Synthesis of nano-Sb4O5Cl2 and its adsorption on mica surface
    WANG Binguo,FENG Li,SONG Shuojiang,CAO Suhong,MA Xia,LIU Jiongtian
    2008, 27(4):  544. 
    Abstract ( 1784 )  
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    Monodispersed nano-Sb4O5Cl2 was prepared from SbCl3 as raw material via alkoxide hydrolysis. Various factors and levels in the preparation of monodispersed Sb4O5Cl2 nanoparticles were studied with orthogonal test. The effects of the type of surfactants as dispersant on the size and morphology were also studied with TEM. Meantime,the adsorption of Sb4O5Cl2 on the surface of mica was also studied. The results showed that the optimum conditions of preparing monodispersed Sb4O5Cl2 nanoparticles were reaction temperature 45 ℃,hydrolysis time 20 min,concentration of SbCl3 0.08 g/mL,stirring speed 350 r/min,water added volume 40 mL,alcoholysis time 2.5 h with isopropanol as alcoholysis reagent. And the surfactants,as shown in the experiments,had a significant effect on the dispersion and morphology of Sb4O5Cl2 nanoparticles. The result also showed that electrostatic attraction reached a maximum after mica was immersed in MnCl2 solution for 15 min so that the amount of Sb4O5Cl2 particles adsorbed on the surface of mica was the greatest. The final nano-Sb4O5Cl2 particles were uniformly well-dispersed.
    Kinetics of synthesis of 1,1,1,3-tetrachloropropane
    DING Yuansheng,ZHANG Jianjun,WU Jiangping,HAN Guoqing,FANG Xiaoqing
    2008, 27(4):  550. 
    Abstract ( 1619 )  
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    The telomerization reaction kinetics of 1,1,1,3- tetrachloropropane synthesis using tetrachloromethane and ethylene as raw materials was studied. The influence of catalyst concentration,pressure,temperature and other factors on the reaction was investigated by,using phosphate ester,powdered iron and FeCl3 as catalysts. It was found that the telomerization reaction was of first order and activation energy was 59.6 kJ/mol. A reaction kinetic equation was presented as follows:-rA= 6.566×107exp(-5.96×104/RT)CA0(1-xA)。
    Application of high speed counter-current chromatography in isolation of an anti-tumor component originated from an unidentified endophytic fungi
    HU Dejun,XIA Xing,ZHAO Fengsheng,CHEN Daijie,GE Mei
    2008, 27(4):  553. 
    Abstract ( 1739 )  
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    High speed counter-current chromatography (HSCC) was applied to the separation of anti-tumor components from an unidentified endophytic fungi. A biphasic solvent system composed of n-hexane-ethyl acetate-methanol-water (1∶3∶3∶3,volume ratio) was used. The bioactive compound purified and collected was analyzed by high-performance liquid chromatography. A white powder with purity above 99% was obtained. The chemical structure of the bioactive compound was identified with ESI-MS,1H NMR and 13C NMR as cytochalasin N.
    Treatment of phosphate wastewater by magnesium ammonium phosphate precipitation process
    TANG Qi,LUO Guyuan
    2008, 27(4):  558. 
    Abstract ( 1937 )  
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    The feasibility of the treatment of phosphate wastewater by the magnesium ammonium phosphate (MAP) precipitation process was discussed. Some factors affecting the result of removal of ammonium and phosphate, such as pH, molar ratio, reaction time,stirring speed,precipitation time were discussed. When treating the phosphate wastewater with PO43-- P 1753.46 mg/L by adding MgSO4·7H2O and NH4Cl, the better treatment conditions were as follows:pH=9.5,n(Mg)∶n(P)∶n(N)= 1.4∶1.11∶1.0,stirring speed about 200 r/min, reaction time 20 min. When precipitation time was 30 min, the removal ratio of PO43— was 98.69%. The quantity of PO43—-P in the treated water was 9.16 mg/L. The quantity of NH3-N in the treated water was 64.10 mg/L. Sediment was confirmed by scanning microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).
    Synthesis of cationic polyacrylamide flocculant for sludge dewatering
    ZHENG Huaili,LI Lingchun,YU Yang,TANG Xue,YANG You,ZHANG Shengtao
    2008, 27(4):  564. 
    Abstract ( 1733 )  
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    According to the Mannich reaction,initiators were added at appropriate temperatures to acrylamide (AM) and dimethylamino ethyl acrylate methyl chloride (DAC) to initiate a free-radical co-reaction between AM and DAC and then to prepare cationic polyacrylamide (CPAM )macromolecular flocculant. The influences of such factors,as total concentration of monomers,use of initiators,copolymerization temperature,pH value and solubilizer on the main characteristics of CPAM in the process of the co-reaction were investigated,and the optimal reaction conditions were obtained as follows:copolymerization temperature 35 ℃,total concentration of monomers 20%,relative molar ratio 6∶1,composite initiator 0.08%,pH value 7,solubilizer 2 %,time of ventilating nitrogen 15min,and reaction time 5h. Under the conditions above,a CPAM product with good solubility and flocculation property,low combined costs and molecular weight of 3.00×106 was synthesized.
    Modification of ultra-fine coal fly ash and its thermodynamics of Cr6+ adsorption
    LIU Zhuannian
    2008, 27(4):  569. 
    Abstract ( 2155 )  
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    Three kinds of coal fly ash were collected from three thermal power plants. Raw coal fly ash was ball milled and ultra-fine coal fly ash was obtained. The ultra-fine coal fly ash was modified by HCl,H2SO4,NaOH,Ca(OH)2 and Na2CO3,respectively. The results showed that Ca(OH)2 was the best modifier and the removal rates of Cr6+ increased by 2.01~2.44 times after modification. The isotherms of Cr6+ adsorption onto three kinds of modified ultra-fine coal fly ash all could be described by the Langmuir isotherms at 25 ℃,35 ℃ and 45 ℃,and the adsorption process was spontaneous and exothermic. The modification mechanism of Ca(OH)2 and methods of regeneration by desorption were also discussed.
    Influence of centrifugal buoyancy on the heat transfer performance of tube-shell heat exchanger with rod baffle and spiral fluted tube
    MA Youfu,YUAN Yichao,LI Jingfen,ZHOU Wenzhu,HU Xiaohong
    2008, 27(4):  573. 
    Abstract ( 2029 )  
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    Centrifugal buoyancy arising from radial temperature gradient of fluid has a great influence on the enhanced heat transfer performance of swirling flow. An experimental comparative investigation on the influence of centrifugal buoyancy on the heat transfer enhancement of swirling flow was carried out via exchanging hot and cool water in shell-side and tube-side respectively in a swirling flow tube-shell heat exchanger,in which heat transfer was enhanced by spiral fluted tubes and rod baffles. The results showed that the total heat transfer coefficient of heat exchanger with hot water arranged in shell-side was relatively higher by 33% than that with hot water arranged in tube-side. Therefore,the influence of centrifugal buoyancy on the heat transfer performance of tube-shell heat exchanger with swirling flow was not negligible. Furthermore,the influence of centrifugal buoyancy on the performance of heat transfer was more distinct in the case of swirling flow existing in the side of larger thermal resistance.
    Preparation of nano-sized TiO2 immobilized on fly ash microsphere and photocatalytic degradation of phenol
    ZHANG Leguan,ZHU Xinfeng
    2008, 27(4):  577. 
    Abstract ( 2142 )  
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    TiO2 loaded photocatalysts immobilized on fly ash micro-sphere were prepared by the sol-gel methods.The crystal phase and morphology of TiO2/ microsphere were investigated with XRD and SEM. The photocatalytic activities of TiO2/ microsphere with different preparation conditions and TiO2 amounts on micro-sphere were evaluated by degradation of phenol. The results showed the best conditions of preparation as follows:four times of catalyst loading,calcination at 550 ℃ centigrade for 2 hours. When phenol concentration was 102 mg/L,degeneration rate reached 60% after 120 minutes.
    Preparation of convex chitosan membrane with phase-separation-induced concave polystyrene membrane as template
    YANG Julin,ZHOU Changren,LIU Aiming,TIAN Ye1
    2008, 27(4):  581. 
    Abstract ( 1967 )  
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    Polystyrene (PS) membranes with pits of different sizes were presented by liquid phase separation,and then convex chitosan membranes were prepared with the PS membranes as templates. The surface morphology and structure were characterized by using scanning electron microscope,atomic force microscope,and the formation mechanism of membrane with pore structure was proposed. By changing the parameters,such as the volume ratio of glycerol (Gly) and propylene glycol (PG),the temperature of film formation and the rate of evaporation,the membranes with different surface morphologies and microstructures could be obtained. The PS films patterned with concavities were used as templates to fabricate convex patterned chitosan membranes. The sizes of the convexes were determined as about 1~50 μm by scanning electron microscope and atomic force microscope. And the air-water contact angles decreased with the increase of convex size. It could be the biomaterial basis for studying the biological function of cells with different surface convexes.
    Preparation of N-carboxyethyl chitosan hydrogel and its pH-sensitivity
    ZHANG Liyan,LI Zuowei,LI Meilan,ZENG Qingxiao
    2008, 27(4):  585. 
    Abstract ( 2663 )  
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    A polyelectrolyte complexed product——N-carboxyethylchitosan (ACS) was prepared through the Michael reaction between chitosan and acrylic acid,whose structure was confirmed by FTIR spectra and 1H NMR spectra. The pH-sensitivity and swelling behavior of the ACS hydrogel (ACSG) were studied. The results showed that carboxyethyl group was grafted onto the chitosan molecule by the Michael reaction. ACSG was strongly pH-sensitive,and the acidic pH-sensitivity was higher than the basic pH-sensitivity. The swelling behavior of ACSG was different in different buffer solutions. ACSG exhibited better swelling behavior not only in acidic but also in basic conditions,and the smallest swelling ratio (SR) was obtained in pH 5.0 buffer solution. With the increase of glutaraldehyde dosage,the SR of ACSG decreased in different pH buffer solutions. With increasing degree of substitution of carboxyethyl group,SR increased at first and decreased afterward.
    Thermoplastic modification of konjac glucomannan with vinyl acetate
    ZHANG Zhengguang,LUO Xuegang
    2008, 27(4):  590. 
    Abstract ( 1835 )  
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    A novel material,thermoplastic konjac glucomannan (TKGM) was synthesized from KGM,vinyl acetate(VAc) for the first time in this research. This novel material is water resistant and degradable. The influence of different experimental conditions on the graft copolymerization was studied,and the optimal conditions were as follows:ammonium persulfate initiator concentration 12 mmol/L reaction time 3 h,reaction temperature 70 ℃,vinyl acetate concentration 0.52 mol/L. The structure and properties of TKGM were characterized with FTIR,DSC and torque rheometer. The results indicated that graft copolymerization reaction took place between KGM and VAc. The glass transition temperature (Tg) of TKGM was only 0.12 ℃,and there was a melting endothermic peak at about 165 ℃. The maximum torque was only 0.85 N·m,the plasticizing time was 44 s and the balance torque was only 4 N·m. These showed that the TKGM had a good plasticity processability.
    Effect of styrene-ethylene/butylene-styrene elastomer grafted with maleic anhydride on morphology and non-isothermal crystallization behavior of polystyrene/polyamide 6 blends
    TANG Bin,DING Xuejia,XUE Haijiao,LI Hongbo,WU Henglan
    2008, 27(4):  595. 
    Abstract ( 1974 )  
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    Polystyrene/polyamide6(PS/PA6)(weight ratio 50/50 ) and polystyrene/polyamide 6/styrene-ethylene/butylene-styrene elastomer grafted with maleic anhydride(PS/PA6/SEBS-g-MA) (weight ratio 50/50/5) blends were prepared through melt blending. The phase morphologies investigated by using scanning electron microscope(SEM)revealed that co-continuous morphologies were formed in both of the blends of PS/PA6(weight ratio 50/50) and PS/PA6/SEBS-g-MA (weight ratio 50/50/5). But the PS phase and PA6 phase in PS/PA6/SEBS-g-MA (weight ratio 50/50/5)blends became finer than that in PS/PA6(weight ratio 50/50) blends. The non-isothermal crystallization behavior of PA6 in both of the blends was studied with differential scanning calorimetry(DSC). It was found that the onset temperature(T0)and the peak temperature(Tp) of crystallization shifted to higher temperatures,and the whole-time(∆t)and half-time(t1/2)of crystallization decreased after adding 5% SEBS-g-MA in the PS/PA6 blends. Both the Jeziorny’s method and Mo’s method can describe the non-isothermal crystallization kinetics of both of the blends very well. The Avrami exponent of PS/PA6 blends was from 4.40 to 4.91 and the Avrami exponent of PS/PA6/SEBS-g-MA was from 2.47 to 3.25,and Zc of PS/PA6 blends was smaller than that of PS/PA6/SEBS-g-MA by the Jeziorny’s method. When Xt of PA6 in both of the blends reached the same,lgF(T)of PS/PA6/SEBS-g-MA blends was smaller than that of PS/PA6 blends. These demonstrated that SEBS-g-MA could play a role of heterogeneous nuclei. The Ozawa’s method was not suitable for the non-isothermal crystallization kinetics of PS/PA6 blends and PS/PA6/SEBS-g-MA blends.
    Clean technology to synthesize 2,2′ -ethylenebis-(4,6- di-t-amylphenol)
    DU Fei,ZHU Rui
    2008, 27(4):  602. 
    Abstract ( 1801 )  
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    The method with 2,4-di-t-amylphenol and anhydrous trimeric acetaldehyde as raw materials,and water containing acid catalyst and surface active agent as reaction solvent,was used to synthesize 2,2′-ethylenebis-(4,6-di-t-amylphenol). The optimum conditions of synthesis were determined as follows:molar ratio of 2,4-di-t-amylphenol and anhydrous trimeric acetaldehyde 2∶1.2,amount of water 180 g,amount of emulsifier 0.5 g,and amount of catalyst 11.0 g at reacting temperature 80~83℃ for 5 h. The process of clean cyclic production was adopted to recycle the reaction solvent,and also resolve the problem of pollution of phenol-containing waste water of traditional production technology. Under these optimal conditions,the yield of the product bisphenol H was over 93.3% and the conversion of 2,4-di-t-amylphenol could be up to 94.3%.
    In-situ preparation and characterization of light scattering PS/PMMA composite materials by adding SBR
    LI Haihua,MENG Qinghua,MENG Qingyun
    2008, 27(4):  606. 
    Abstract ( 1842 )  
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    Preparation of PS/PMMA composite materials by adding styrene butadiene rubber (SBR) was performed by in-situ two steps polymerization. The effect of the amount of SBR scattering substance on the optical properties of composite materials was investigated. The results indicated that the addition of SBR powder could have a synergistic effect with the MMA pre-polymer. The haze curve of the sample versus pre-polymeric MMA’s amount and SBR’s amount showed an oscillating variation relationship. The transmittance curves of the sample versus pre-polymeric MMA’s content was also an oscillating variation relationship,but the transmittance curve of the sample versus SBR’s content was not apparent oscillating variation relationship. The morphology of the composite materials was characterized with SEM. The surface of a notched sample showed that SBR particles were uniformly dispersed in the matrix.
    Thermal degradation mechanism of polystyrene by TG-MS
    ZHANG Minhua,LI Chunhua,JIANG Haoxi
    2008, 27(4):  609. 
    Abstract ( 2057 )  
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    Thermal degradation of polystyrene was investigated with thermogravimetry-mass spectrum analysis (TG-MS). The selectivity of styrene was much higher than other degradation products,suggesting initiation of thermal degradation from chain end scission. Styrene dimer appeared at the last stage of polystyrene degradation,indicating that styrene dimer was possibly the residue of polystyrene degradation
    应用技术
    Optimal revamping of phosgene-recirculation system in TDI production
    BI Rongshan,TAN Xinshun,YUE Jincai,ZHENG Shiqing,MA Lianxiang
    2008, 27(4):  613. 
    Abstract ( 1755 )  
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    The process of phosgene-recirculation system in toluene diisocynate (TDI) production is analysed and two shortcomings of the old process are found:① High hydrogen chloride concentration of phosgene will decrease the reaction’s yield and ② The phosgene in the kettle under saturated state will become a potential hazard. In order to overcome these two shortcomings, a tower is added to purify the phosgene which is supercooled before entering the kettle to ensure safety. Compared with the old process, the weight percent of hydrogen chloride in phosgene decreases from 0.3% to 0.1%, a reduction of about 66.7%. Without any increase in refrigeration, the phosgene in the kettle is kept in a super-cooled state and production safety is improved.
    On-line calculation and analysis of heat efficiency of circulating fluidized bed boiler unit
    SONG Bo,JIANG Qingyin,CAO Zhikai
    2008, 27(4):  616. 
    Abstract ( 2676 )  
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    A new method of on-line calculation of heat efficiency of circulating fluidized bed boiler (CFB Boiler) was proposed. Based on some measurable operation parameters, including pressure, temperature and the flow rates of main steam, water and primary and secondary air, which were collected online, input energy and the utilization of energy in effect could be deduced respectively, and then heat efficiency could be calculated. Using the plant-site data from a 135 t/h CFB boiler unit in Fujian, the online calculation of heat efficiency was simulated and the result of industrial simulation indicated that this method was accurate and effective. Furthermore, orthogonal experiment was performed to analyze seven factors which contributed to heat efficiency of CFB boiler. Because it is hard to get corresponding data on the orthogonal layout, a Levenberg-Marquardt (LM)_back propagation (BP) algorithm-based predictive model was established by using the data collected from plant-site and on-line calculation model. The result of orthogonal experiment indicated that air/coal ratio, main steam pressure and boiler firebox temperature were key factors. The result was validated by the industrial optimization experiment. This method will help on-line optimal operation of the CFB boiler.
    Waste minimization in ammonolysis process of O,O-dimethylphosphorochloridothioate
    AI Qiuhong,LUO He’an
    2008, 27(4):  621. 
    Abstract ( 1876 )  
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    In order to minimize the waste production in the conventional ammonolysis process of O,O-dimethylphosphorochloridothioate, some source reduction measures were developed,including using O,O-dimethylphosphorochloridothioate instead of benzene as extractant, improving the purity of the starting material O,O-dimethylphosphorochloridothioate,converting conventional batch STR reactor to a recycle tubular reactor,adopting more effective extraction equipment,optimizing operation conditions and using automatic control. At the same time,the wastewater was recycled and ammonia chloride was recovered in the ammonolysis process. These waste minimization measures have been implemented in an industrial process,leading to significantly less waste generation and much lower production cost.
    Simulation and optimization of industrial two-stage ammonia-water absorption refrigeration system
    SUN Daoqing,ZHANG Shuwei,LIU Jian
    2008, 27(4):  625. 
    Abstract ( 2332 )  
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    Based on improved PSRK equation of state model,the simulation of industrial two-stage ammonia-water absorption refrigeration system was perfomed with the help of Aspen Plus software. Analysis of the process was made,and the best split fraction was presented. The change of ξ(coefficient of performance) with the concentrations of ammonia-water from high pressure absorption and low pressure absorption systems was deduced,and several methods to enhance the absorption were proposed.
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